1. A light receiving IC which can be mounted on an electronic device having an OLED panel,

the light receiving IC includes:

a driving unit that drives the first light source and the second light source that emit light, respectively; and

a light receiving element for detecting the reflected light,

the light receiving IC, the first light source and the second light source are arranged in an area covered by the OLED panel on the lower side of the OLED panel,

the first light source is disposed closer to the light receiving element than the second light source,

the driving unit reduces the intensity of light emitted from the first light source to be lower than the intensity of light emitted from the second light source.

2. A light receiving IC according to claim 1,

the driving section drives the first light source and the second light source at the same timing, and the first light source and the second light source emit light at the same timing,

the light receiving IC has a control logic for determining whether or not the amount of light received by the light receiving element is equal to or greater than a threshold value.

3. A light receiving IC according to claim 1,

the driving section drives the first light source and the second light source at different timings, the first light source and the second light source emitting light at different timings,

the light receiving IC includes a control logic that performs a first determination of whether or not the amount of light received by the light receiving element is equal to or greater than a first threshold value when the first light source emits light, performs a second determination of whether or not the amount of light received by the light receiving element is equal to or greater than a second threshold value when the second light source emits light, and calculates a logical sum of the first determination result and the second determination result.

4. A light receiving IC according to any one of claims 1 to 3,

the first light source is a first LED, the second light source is a second LED,

the driving unit drives the first LED and the second LED.

5. A light receiving IC according to claim 4,

the drive unit includes:

a first driver that drives the first LED;

a second driver that drives the second LED; and

a pulse generator that outputs a first pulse width modulation signal transmitted to the first driver and a second pulse width modulation signal transmitted to the second driver,

the amplitude of the first pulse width modulated signal is less than the amplitude of the second pulse width modulated signal.

6. A light receiving IC according to claim 4,

the driving section has a common driver that drives the first LED and the second LED,

the first LED and the second LED are connected with a power supply,

the current supplied from the power source to the first LED is smaller than the current supplied from the power source to the second LED.

7. A light receiving IC according to claim 4,

the driving section has a common driver that drives the first LED and the second LED,

the current supplied from the common driver to the first LED is less than the current supplied from the common driver to the second LED.

8. A light receiving IC which can be mounted on an electronic device having an OLED panel,

the light receiving IC includes:

a driving unit that drives the first light source and the second light source that emit light, respectively; and

a light receiving element for detecting the reflected light,

the light receiving IC, the first light source and the second light source are arranged in an area covered by the OLED panel on the lower side of the OLED panel,

the first light source is disposed closer to the light receiving element than the second light source,

the driving unit makes the intensity of the light emitted from the first light source the same as the intensity of the light emitted from the second light source,

the driving section drives the first light source and the second light source at different timings, the first light source and the second light source emitting light at different timings,

the light receiving IC includes a control logic that performs a first determination of whether or not the amount of light received by the light receiving element is equal to or greater than a first threshold value when the first light source emits light, performs a second determination of whether or not the amount of light received by the light receiving element is equal to or greater than a second threshold value when the second light source emits light, and calculates a logical sum of the first determination result and the second determination result.

9. A light receiving IC according to claim 8,

the first light source is a first LED, the second light source is a second LED,

the driving unit drives the first LED and the second LED.

10. A non-contact sensor, characterized in that,

the non-contact sensor has:

a light receiving IC according to claim 6;

the first LED and the second LED;

a first limiting resistance element disposed between the first LED and the power supply; and

a second limiting resistance element disposed between the second LED and the power source,

the resistance value of the first limiting resistance element is larger than the resistance value of the second limiting resistance element.

11. A non-contact sensor, characterized in that,

the non-contact sensor has:

a light receiving IC according to claim 6;

the first LED and the second LED; and

a first limiting resistance element disposed between the first LED and the power source,

no limiting resistance element is arranged between the second LED and the power supply.

12. A non-contact sensor, characterized in that,

the non-contact sensor has:

a light receiving IC according to claim 7;

the first LED and the second LED;

a first limiting resistance element configured between the first LED and the common driver; and

a second limiting resistance element configured between the second LED and the common driver,

the resistance value of the first limiting resistance element is larger than the resistance value of the second limiting resistance element.

13. A non-contact sensor, characterized in that,

the non-contact sensor has:

a light receiving IC according to claim 7;

the first LED and the second LED; and

a first limiting resistance element configured between the first LED and the common driver,

no limiting resistive element is arranged between the second LED and the common driver.

14. A non-contact sensor, characterized in that,

the non-contact sensor has:

a light receiving IC according to claim 4, 5, 6, 7 or 9; and

the first LED and the second LED.

15. The non-contact sensor of claim 14,

the light receiving IC, the first LED, and the second LED are mounted on different modules.

16. An electronic device, characterized in that,

the electronic device has:

the OLED panel; and

a non-contact sensor according to any one of claims 10 to 15.

17. A light receiving IC which can be mounted on an electronic device having an OLED panel,

the light receiving IC includes:

a drive unit that drives 3 or more light sources that emit light, respectively; and

a light receiving element for detecting the reflected light,

the light receiving IC and the 3 or more light sources are disposed in a region covered by the OLED panel on the lower side of the OLED panel,

the intensity of light emitted from the light source at a position close to the light receiving element is smaller than the intensity of light emitted from the light source at a position far from the light receiving element.

Background

Oled (organic Light Emitting diode) panels incorporating a non-contact sensor are known. For example, an OLED panel described in japanese patent application laid-open No. 2017-27595 includes: a substrate; an OLED stack disposed on the substrate and emitting visible light; and a near-infrared light sensor array disposed between the substrate and the OLED stack, and including a light emitting portion that emits near-infrared light and a light receiving portion that receives near-infrared light.

However, the OLED panel incorporating a proximity sensor disclosed in japanese patent application laid-open No. 2017-27595 has the following problems. Part of the near-infrared light emitted from the light emitting section passes through the OLED stack, is reflected by the object to be detected, and enters the light receiving section. Another part of the near-infrared light emitted from the light emitting section does not pass through the OLED stack, but returns from the OLED stack to the direction of the near-infrared light sensor. When the distance between the light emitting section and the light receiving section is short, the infrared light enters the light receiving section as interference light. The infrared light reflected by the object to be detected is buried by the interference light, and the object detection accuracy of the non-contact sensor is lowered.

Disclosure of Invention

Therefore, an object of the present invention is to provide a light-receiving IC, a proximity sensor, and an electronic device, which have high object detection accuracy.

The present invention is a light receiving IC mountable on an electronic device having an OLED panel, including: a driving unit that drives the first light source and the second light source that emit light, respectively; and a light receiving element for detecting the reflected light. The light receiving IC, the first light source and the second light source are arranged in an area covered by the OLED panel on the lower side of the OLED panel. The first light source is disposed closer to the light receiving element than the second light source. The driving unit makes the intensity of light emitted from the first light source smaller than the intensity of light emitted from the second light source.

Preferably, the driving unit drives the first light source and the second light source at the same timing, so that the first light source and the second light source emit light at the same timing. The light receiving IC has: and a control logic for determining whether or not the light receiving amount of the light receiving element is equal to or greater than a threshold value.

Preferably, the driving unit drives the first light source and the second light source at different timings, so that the first light source and the second light source emit light at different timings. The light receiving IC has: and a control logic that performs a first determination of whether or not the light receiving amount of the light receiving element is equal to or greater than a first threshold value when the first light source emits light, performs a second determination of whether or not the light receiving amount of the light receiving element is equal to or greater than a second threshold value when the second light source emits light, and calculates a logical sum of the first determination result and the second determination result.

Preferably, the first light source is a first LED and the second light source is a second LED. The driving part drives the first LED and the second LED.

Preferably, the driving unit includes: a first driver that drives the first LED; a second driver that drives a second LED; and a pulse generator that outputs a first pulse width modulation signal to the first driver and a second pulse width modulation signal to the second driver. The amplitude of the first pulse width modulated signal is less than the amplitude of the second pulse width modulated signal.

Preferably, the driving unit includes: a common driver that drives the first LED and the second LED. The first LED and the second LED are connected with a power supply. The current supplied from the power supply to the first LED is smaller than the current supplied from the power supply to the second LED.

Preferably, the driving unit includes: a common driver that drives the first LED and the second LED. The current supplied to the first LED from the common driver is smaller than the current supplied to the second LED from the common driver.

The present invention is a light receiving IC mountable on an electronic device having an OLED panel, including: a driving unit that drives the first light source and the second light source that emit light, respectively; and a light receiving element for detecting the reflected light. The light receiving IC, the first light source and the second light source are arranged in an area covered by the OLED panel on the lower side of the OLED panel. The first light source is disposed closer to the light receiving element than the second light source. The driving unit makes the intensity of the light emitted from the first light source the same as the intensity of the light emitted from the second light source. The driving unit drives the first light source and the second light source at different timings, whereby the first light source and the second light source emit light at different timings. The light receiving IC has: and a control logic that performs a first determination of whether or not the light receiving amount of the light receiving element is equal to or greater than a first threshold value when the first light source emits light, performs a second determination of whether or not the light receiving amount of the light receiving element is equal to or greater than a second threshold value when the second light source emits light, and calculates a logical sum of the first determination result and the second determination result.

Preferably, the first light source is a first LED and the second light source is a second LED. The driving section drives the first LED and the second LED.

Preferably, the contactless sensor has: the light receiving IC described above; a first LED and a second LED; a first limiting resistance element configured between the first LED and the power supply; and a second limiting resistance element configured between the second LED and the power supply. The resistance value of the first limiting resistance element is larger than the resistance value of the second limiting resistance element.

Preferably, the contactless sensor has: the light receiving IC described above; a first LED and a second LED; and a first limiting resistance element configured between the first LED and the power supply. No limiting resistance element is arranged between the second LED and the power supply.

Preferably, the contactless sensor has: the light receiving IC described above; a first LED and a second LED; a first limiting resistance element configured between the first LED and the common driver; and a second limiting resistance element configured between the second LED and the common driver. The resistance value of the first limiting resistance element is larger than the resistance value of the second limiting resistance element.

Preferably, the contactless sensor has: the light receiving IC described above; a first LED and a second LED; and a first limiting resistance element configured between the first LED and the common driver. No limiting resistive element is arranged between the second LED and the common driver.

Preferably, the contactless sensor has: the light receiving IC described above, and the first LED and the second LED.

Preferably, the light receiving IC, the first LED, and the second LED are mounted on different modules.

Preferably, the electronic device has: the OLED panel described above and the proximity sensor described above.

The present invention is a light receiving IC mountable on an electronic device having an OLED panel, including: a drive unit that drives 3 or more light sources that emit light, respectively; and a light receiving element for detecting the reflected light. The light receiving IC and the 3 or more light sources are disposed in a region covered by the OLED panel on the lower side of the OLED panel. The intensity of light emitted from the light source at a position close to the light receiving element is smaller than the intensity of light emitted from the light source at a position far from the light receiving element.

According to the present invention, the first light source is disposed closer to the light receiving element than the second light source, and the intensity of light emitted from the first light source is made smaller than the intensity of light emitted from the second light source, whereby the object can be detected with high accuracy.

Further, according to the present invention, the first light source is disposed closer to the light receiving element than the second light source, the intensity of light emitted from the first light source and the intensity of light emitted from the second light source are made the same, and the first light source and the second light source emit light at different timings, whereby the object can be detected with high accuracy.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a diagram showing a main configuration of a smartphone according to an embodiment.

Fig. 2 is a diagram showing an example of the structure of the OLED panel 5.

Fig. 3 is a diagram for explaining light interference in the case where the light emitting unit 10 is formed of 1 LED.

Fig. 4 is a diagram showing response characteristics of the light receiving element 34 when the LED21 is close to the light receiving element 34.

Fig. 5 is a diagram showing response characteristics of the light receiving element when the LED21 is distant from the light receiving element 34.

Fig. 6 is a diagram showing the arrangement of the proximity sensor 9 according to the first embodiment.

Fig. 7 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the first embodiment.

Fig. 8 is a diagram showing response characteristics of the light receiving element 34 according to the first embodiment.

Fig. 9 is a diagram showing the structure of the proximity sensor 9 according to the first embodiment.

Fig. 10 is a timing diagram of the enable signal EN, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb.

Fig. 11 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the second embodiment.

Fig. 12 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the third embodiment.

Fig. 13 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the fourth embodiment.

Fig. 14 is a diagram showing response characteristics of the light receiving element 34 according to the fourth embodiment.

Fig. 15 is a diagram showing a configuration of a proximity sensor 9 according to a fifth embodiment.

Fig. 16 is a diagram showing a configuration of a proximity sensor 9 according to a sixth embodiment.

Fig. 17 is a diagram showing a configuration of a proximity sensor 9 according to a seventh embodiment.

Fig. 18 is a diagram showing a configuration of a proximity sensor 9 according to an eighth embodiment.

Fig. 19 is a diagram showing a configuration of a proximity sensor 9 according to a ninth embodiment.

Fig. 20 is a timing chart of the enable signals ENa and ENb, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb in the ninth embodiment.

Fig. 21 is a flowchart showing a procedure of an operation of the proximity sensor 9 according to the ninth embodiment.

Fig. 22 is a diagram showing an example of the first determination result, the second determination result, and the integrated determination result.

Fig. 23 is a timing chart of the enable signals ENa and ENb, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb in the tenth embodiment.

Fig. 24 is a flowchart showing a procedure of the operation of the proximity sensor 9 according to the tenth embodiment.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings.

In the following description, a smartphone is described as an example of an electronic device, but the electronic device is not limited to this and includes a touch panel, a television, a camera, a music player, a portable communication device other than a smartphone, and the like.

[ first embodiment ]

In the following description, a smartphone will be described as an example of an electronic device.

Fig. 1 is a diagram showing a main configuration of a smartphone according to an embodiment.

The smartphone 100 includes: the wireless communication device includes an antenna 2, a wireless communication unit 3, a touch panel 4, an OLED panel 5, an illuminance sensor 6, a speaker 7, a microphone 8, a proximity sensor 9, an acceleration sensor 16, a gyro sensor 17, a control circuit 12, and a battery 15. The noncontact sensor 9 has a light emitting portion 10 and a light receiving ic (integrated circuit) 11. The control circuit 12 has a processor 13 and a memory 14.

The antenna 2 transmits a radio signal to a base station and receives a radio signal from the base station.

The wireless communication unit 3 amplifies and down-converts the wireless signal transmitted from the antenna 2, and outputs the signal to the control circuit 12. The wireless communication unit 3 up-converts and amplifies a transmission signal including an audio signal and the like generated by the control circuit 12, and outputs the processed wireless signal to the antenna 2.

The touch panel 4 detects contact or proximity of an object such as a finger of a user, and outputs a detection signal corresponding to the detection result to the control circuit 12.

The microphone 8 converts sound input from the outside of the smartphone 100 into an electric sound signal and outputs the electric sound signal to the control circuit 12.

The speaker 7 converts an electric sound signal from the control circuit 12 into a sound output.

The acceleration sensor 16 detects the acceleration of the smartphone 100.

The gyro sensor 17 detects the rotation speed of the smartphone 100.

The OLED panel 5 displays various information such as characters, symbols, and figures under the control of the control circuit 12.

The illuminance sensor 6 detects illuminance in the surrounding environment, and outputs a detection signal corresponding to the detection result to the control circuit 12.

The proximity sensor 9 detects the approach of an object, and outputs a detection signal corresponding to the detection result to the control circuit 12. When detecting the approach of an object, the control circuit 12 sets the touch panel 4 and the OLED panel 5 to the off state.

The light emitting section 10 emits infrared light. The light emitting section 10 includes a light source. The light source is, for example, an led (light Emitting diode).

The light receiving IC11 controls emission of infrared light by the light emitting section 10, and detects infrared light emitted from the light emitting section 10 and reflected by an object.

The processor 13 is composed of a cpu (central Processing unit), a dsp (digital Signal Processing), and the like.

The memory 14 stores a control program for controlling the smartphone 100, a plurality of application programs, and the like. The various functions of the control circuit 12 are implemented by the processor 13 executing various programs within the memory 14.

The battery 15 supplies power to the electronic components contained in the smartphone 100.

Fig. 2 is a diagram showing an example of the structure of the OLED panel 5.

The OLED panel 5 has: a substrate film 71, an inorganic film 72, an OLED layer 76, a sealing body 75, a side sealing body 73, and a sealing film 74.

The substrate film 71 is formed of a polymer material. The inorganic film 72 is formed on the substrate film 71. The inorganic film 72 is formed of an inorganic material. The OLED layer 76 is formed on the inorganic film 72. The OLED layer 76 has layers such as an anode layer, a cathode layer, and a light-emitting layer, and has a plurality of OLED elements. The sealing body 75 is formed on the inorganic film 72. The sealing body 75 is formed of a material containing a polymer material as a main component. The encapsulant 75 surrounds the OLED layer 76, protecting the OLED layer 76. The sealing film 74 is formed to cover the upper portion of the sealing body 75. The sealing film 74 is formed of glass or metal. The side seal 73 is formed to cover the side of the seal 75. The side seal 73 is made of a polymer material and an additive.

The OLED panel 5 formed by these elements has a transmittance of 1-10% with respect to infrared light emitted from the LEDs.

Fig. 3 is a diagram for explaining light interference in the case where the light emitting unit 10 is formed of 1 LED.

The touch panel 4 is disposed in contact with the lower side of the cover panel 51. The OLED panel 5 is configured to be in contact with the lower side of the touch panel 4. A light shielding film 24 is formed on a part of the lower side of the OLED panel 5. A main substrate 61 is disposed below the OLED panel 5. The main board 61 is provided with a light receiving IC module 54 and an LED module 53. A light shielding wall 25 is disposed between the light receiving IC module 54 and the LED module 53. The lower surface of the light-shielding wall 25 is connected to the main substrate 61, and the upper surface of the light-shielding wall 25 is connected to the OLED panel 5.

The light receiving IC module 54 includes: a base substrate 60, a light receiving IC11, a transparent case member 57, and a light condensing member 55. The light receiving IC11 is electrically connected to the main substrate 61. The light condensing member 55 condenses the infrared light reflected by the object RF and transmits the condensed infrared light to the light receiving element 34 in the light receiving IC 11.

The LED module 53 has: a base substrate 59, an LED21, a transparent housing member 58, and a light collection member 56. The LED21 is electrically connected to the main substrate 61. The light collecting member 56 collects the infrared light emitted from the LED21 and outputs the infrared light to the outside of the LED module 53.

A part of the infrared light emitted from the LED21 is reflected by the object RF and input to the light receiving element 34 of the light receiving IC module 54. Another part of the infrared light emitted from the LED21 of the LED module 53 is returned from the OLED panel 5 to the direction of the proximity sensor without passing through the OLED panel 5.

If the LED32 is close to the light receiving element 34, the infrared light enters the light receiving element 34 as interference light of a large intensity. The infrared light reflected by the object RF is buried in the interference light having a large intensity, and the object RF detection accuracy of the proximity sensor is lowered. The light receiving element 34 receives not only the reflected light from the object RF but also the interference light, and therefore, there is a problem in that the detection accuracy of the object RF by the proximity sensor 9 is lowered.

On the other hand, if the distance between the LED32 and the light receiving element 34 is long, there is a problem that the object RF at a position extremely close to the proximity sensor 9 cannot be detected.

Fig. 4 is a diagram showing response characteristics of the light receiving element 34 when the LED21 is close to the light receiving element 34. The horizontal axis represents the distance between the light receiving element 34 and the object RF. The vertical axis represents the light receiving amount of the light reflected by the light receiving element 34 with respect to the object RF. The light receiving amount is obtained by multiplying the current value of the light receiving element 34 by a constant coefficient. In fig. 4, the amount of light received by the light receiving element 34 for the interference light is about 1000. The threshold THA is set to about 2000.

As shown in fig. 4, when the light receiving amount is equal to or greater than the threshold THA, it can be determined that the object RF is present at a short distance (12[ mm ] or less) from the light receiving element 34. However, when the distance between the light receiving element 34 and the object RF is 30[ mm ] or more, the reflected light is buried by the interference light, and therefore, it is impossible to determine whether the object RF exists at a short distance or a long distance from the light receiving element 34.

Fig. 5 is a diagram showing response characteristics of the light receiving element 34 when the LED21 is distant from the light receiving element 34. In fig. 5, the light receiving element 34 receives about 25 amounts of interference light. The threshold THB is set to about 150.

As shown in fig. 5, when the light receiving amount is equal to or greater than the threshold THB, it can be determined that the distance between the object RF and the light receiving element 34 is 7[ mm ] to 30[ mm ]. However, when the light receiving amount is smaller than the threshold THB, it cannot be determined whether the distance between the object RF and the light receiving element 34 is smaller than 7[ mm ] or larger than 30[ mm ].

In order to solve such a problem, the proximity sensor 9 of the present embodiment includes a first light source (first LED) that emits light for detecting a position close to the proximity sensor 9 and a second light source (second LED) that emits light for detecting a position far from the proximity sensor 9. The intensity of light emitted from the first light source is less than the intensity of light emitted from the second light source.

Fig. 6 is a diagram showing the arrangement of the proximity sensor 9 according to the first embodiment.

In the first embodiment, the light receiving IC11, the first LED21-a, and the second LED21-b are disposed in the area covered by the OLED panel 5 on the lower side of the touch panel 4 and the OLED panel 5.

When the detection of the proximity of the object to the proximity sensor 9 and the input to the touch panel 4 occur simultaneously, the detection of the proximity of the object to the proximity sensor 9 can be prioritized. In order to avoid detection of proximity of an object by the proximity sensor 9 and competition with input to the touch panel 4 as much as possible, the light-receiving IC11, the first LED21-a, and the second LED21-b may be disposed only at the corner of the region covered by the OLED panel 5. For example, as shown in FIG. 6, the light receiving IC11, the first LED21-a, and the second LED21-b may be disposed at the upper right corner. Further, the item indicated by the user touch may not be displayed in the upper right area.

Fig. 7 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the first embodiment. Fig. 7 shows the arrangement of the plane parallel to the XZ plane.

The touch panel 4 is disposed in contact with the lower side of the cover panel 51. The OLED panel 5 is configured to be in contact with the lower side of the touch panel 4. A light shielding film 24 is formed on a part of the lower side of the OLED panel 5. A main substrate 61 is disposed below the OLED panel 5. The main substrate 61 is provided with a light receiving IC module 54, a first LED module 53-a, and a second LED module 53-b. The light shielding wall 25 is disposed between the light receiving IC module 54 and the first LED module 53-a, and between the first LED module 53-a and the second LED module 53-b. The lower surface of the light-shielding wall 25 is connected to the main substrate 61, and the upper surface of the light-shielding wall 25 is connected to the OLED panel 5.

The light receiving IC module 54 includes: a base substrate 60, a light receiving IC11, a transparent case member 57, and a light condensing member 55. The light receiving IC11 is electrically connected to the main substrate 61. The light condensing member 55 condenses the infrared light reflected by the object RF and transmits the condensed infrared light to the light receiving element 34 in the light receiving IC 11.

The first LED module 53-a has: a base substrate 59-a, a first LED21-a, a transparent housing member 58-a, and a light collection optic 56-a. The first LED21-a is electrically connected to the main substrate 61. The light collecting member 56-a collects the infrared light emitted from the first LED21-a and outputs the infrared light to the outside of the first LED module 53-a.

The second LED module 53-b has: a base substrate 59-b, a second LED21-b, a transparent housing member 58-b, and a light collection optic 56-b. The second LED21-b is electrically connected to the main substrate 61. The light collecting unit 56-b collects the infrared light emitted from the second LED21-b and outputs the infrared light to the outside of the second LED module 53-b.

The intensity of light emitted from the first LED21-a located at a position close to the light receiving element 34 is smaller than the intensity of light emitted from the second LED21-b located at a position distant from the light receiving element 34.

The ratio of the intensity of light emitted from the first LED21-a to the intensity of light emitted from the second LED21-b is adjusted according to the distance between the first LED21-a and the light receiving element 34, the distance between the second LED21-b and the light receiving element 34, the size of the light shielding wall 25, and the like. For example, the distance between the first LED21-a and the light receiving element 34 is set to 4[ mm ], the distance between the second LED21-b and the light receiving element 34 is set to 10[ mm ], and the ratio of the intensity of infrared light emitted from the first LED21-a to the intensity of infrared light emitted from the second LED21-b can be 1/10 to 1/5.

A part of the infrared light emitted from the first LED21-a is reflected by the object RF and input to the light receiving element 34 of the light receiving IC module 54. Since the OLED panel 5 has low transmittance of infrared light, a part of the infrared light emitted from the first LED21-a is emitted toward the light receiving element 34 as interference light without passing through the OLED panel 5.

A part of the infrared light emitted from the second LED21-b is reflected by the object RF and input to the light receiving element 34 of the light receiving IC module 54. Since the OLED panel 5 has low transmittance of infrared light, a part of the infrared light emitted from the second LED21-b is emitted toward the light receiving element 34 as interference light without passing through the OLED panel 5.

The light receiving element 34 receives not only the reflected light from the object RF but also interference light. However, in the present embodiment, since the intensity of the light obtained by combining the reflected light generated by the light emitted from the first LED21-a and the reflected light generated by the light emitted from the second LED21-b is greater than the intensity of the interference light, there is no problem in that the detection accuracy of the object RF by the proximity sensor 9 is lowered.

Fig. 8 is a diagram showing response characteristics of the light receiving element 34 according to the first embodiment. The horizontal axis represents the distance between the light receiving element 34 and the object RF. The ratio of the distance between the first LED21-a and the light receiving element 34, the distance between the second LED21-b and the light receiving element 34, the intensity of infrared light emitted from the first LED21-a, and the intensity of infrared light emitted from the second LED21-b is adjusted to an appropriate level. The vertical axis represents the light receiving amount of the light reflected by the light receiving element 34 with respect to the object RF. The light receiving amount is obtained by multiplying the current value of the light receiving element 34 by a constant coefficient. In fig. 8, the light receiving amount of the light receiving element 34 for the interference light is about 300. The threshold THC is set to about 500.

Referring to fig. 4 and 8, the main component of the response characteristic when the object RF is close to the light receiving element 34 is the response characteristic of the first LED21-a located close to the light receiving element 34. Referring to fig. 5 and 8, the main component of the response characteristic when the object RF is far from the light receiving element 34 is the response characteristic of the second LED21-b at a position far from the light receiving element 34. When the amount of received light is equal to or greater than the threshold value THC, it can be determined that the object RF is present at a distance (26[ mm ] or less) from the light-receiving element. When the amount of received light is less than the threshold THC, it can be determined that the object RF is present at a distance (more than 26[ mm ]) away from the light-receiving element.

Fig. 9 is a diagram showing the structure of the proximity sensor 9 according to the first embodiment.

The light receiving IC11 includes: a control logic 31, a pulse generator 32, a driving section 39 including a first driver 33-a and a second driver 33-b, a light receiving element 34, an amplifier 35, and an ADC 36. The light emitting section 10 includes a first LED21-a and a second LED 21-b.

Control logic 31 controls the driving of first LED21-a and second LED21-b in accordance with instructions from processor 13. The control logic 31 controls the timing of the emission of infrared light from the first LED21-a and the timing of the emission of infrared light from the second LED21-b by the enable signal EN.

The pulse generator 32 outputs a first pulse width modulation signal PWMa and a second pulse width modulation signal PWMb. The amplitude AP of the first pulse width modulation signal PWMa is smaller than the amplitude BP of the second pulse width modulation signal PWMb.

The first driver 33-a drives the first LED21-a in accordance with a first pulse width modulated signal PWMa. The second driver 33-b drives the second LED21-b in accordance with a second pulse width modulated signal PWMb. Since the amplitude AP of the first pulse width modulation signal PWMa is smaller than the amplitude BP of the second pulse width modulation signal PWMb, the driving unit 39 can set the intensity of the infrared light emitted from the first LED21-a to be smaller than the intensity of the infrared light emitted from the second LED 21-b.

The driving section 39 drives the first LED21-a and the second LED21-b at the same timing. The control logic 31 determines whether or not the light receiving amount of the light receiving element 34 is equal to or greater than a threshold value THC. The control logic 31 determines that the object RF is present at a distance close to the light-receiving element 34 when the light-receiving amount of the light-receiving element 34 is equal to or greater than the threshold THC, and determines that the object RF is present at a distance far from the light-receiving element 34 when the light-receiving amount of the light-receiving element 34 is less than the threshold THC.

The light receiving element 34 detects infrared light reflected by the object RF. The light receiving element 34 is formed of a photodiode.

The amplifier 35 amplifies the output signal of the light receiving element 34.

The ADC36 converts the output signal of the amplifier 35 into a digital signal, and outputs the digital signal to the control logic 31.

In the present embodiment, as in the embodiment described later, there is an advantage that the light emitting unit 10 does not need to be provided with a limiting resistance element.

Fig. 10 is a timing diagram of the enable signal EN, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb.

At time T1, when the enable signal EN is activated by the control logic 31, the generation of the first and second pulse width modulation signals PWMa and PWMb of the pulse generator 32 is started at time T1. Thus, the driving section 39 drives the first LED21-a and the second LED21-b at the same timing. As a result, the timing of starting emission of infrared light from the first LED21-a and the timing of starting emission of infrared light from the second LED21-b can be set simultaneously.

At time T2, when the enable signal EN is inactive by the control logic 31, the generation of the first and second pulse width modulation signals PWMa and PWMb by the pulse generator 32 is ended at time T2. Thus, the driving unit 39 ends the driving of the second LED21-a and the driving of the second LED21-b at the same timing. As a result, the end timing of the emission of infrared light from the first LED21-a and the end timing of the emission of infrared light from the second LED21-b can be synchronized.

[ second embodiment ]

In the first embodiment, as shown in fig. 7, the first LED module 53-b is disposed between the light receiving IC module 54 and the second LED module 53-b. The present embodiment differs from the first embodiment in the arrangement of the proximity sensor 9.

Fig. 11 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the second embodiment. Fig. 11 shows the arrangement of the plane parallel to the XZ plane.

As shown in fig. 11, a light receiving IC module 54 is disposed between the first LED module 53-a and the second LED module 53-b.

In this embodiment, the first LED21-a is also disposed at a position close to the light receiving element 34, and the second LED21-b is also disposed at a position far from the light receiving element 34. The intensity of light emitted from the first LED21-a is less than the intensity of light emitted from the second LED 21-b.

[ third embodiment ]

Fig. 12 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the third embodiment. Fig. 12 shows the arrangement of the plane parallel to the XZ plane.

As shown in fig. 12, in the third embodiment, the light shielding wall 25 is not provided. Instead, the shell members 157, 158-a, 158-b are formed of light-shielding shell members.

[ fourth embodiment ]

Fig. 13 is a diagram showing the arrangement inside the cover panel 51 in the electronic apparatus 100 according to the fourth embodiment. Fig. 13 shows the arrangement of the plane parallel to the XZ plane.

The light emitting unit 10 of the present embodiment includes: a first LED module 53-a, a second LED module 53-b and a third LED module 53-c.

The main substrate 61 is provided with a light receiving IC module 54, a first LED module 53-a, a second LED module 53-b, and a third LED module 53-c. The light shielding wall 25 is disposed between the light receiving IC module 54 and the first LED module 53-a, between the first LED module 53-a and the second LED module 53-b, and between the second LED module 53-b and the third LED module 53-c. The lower surface of the light-shielding wall 25 is connected to the main substrate 61, and the upper surface of the light-shielding wall 25 is connected to the OLED panel 5.

The first and second LED modules 53-a and 53-b have the same structure as the first embodiment.

The third LED module 53-c has: a base substrate 59-c, a third LED21-c, a transparent housing member 58-c, and a light collection member 56-c. The third LED21-c is electrically connected to the main substrate 61. The light collecting unit 56-c collects the infrared light emitted from the third LED21-c and outputs the infrared light to the outside of the third LED module 53-c.

The intensity of infrared light emitted from an LED located close to the light receiving element 34 is lower than the intensity of infrared light emitted from an LED located far from the light receiving element 34. That is, since the first LED21-a, the second LED21-b, and the third LED21-c are arranged in this order from the position close to the light receiving element 34, the intensity of the emitted infrared light is, in order from small to large, the infrared light of the first LED21-a, the infrared light of the second LED21-b, and the infrared light of the third LED 21-c.

The ratio of the intensity of light emitted from the first LED21-a, the intensity of light emitted from the second LED21-b, and the intensity of light emitted from the third LED21-c is adjusted according to the distance between the first LED21-a and the light receiving element 34, the distance between the second LED21-b and the light receiving element 34, the distance between the third LED21-c and the light receiving element 34, the size of the light shielding wall 25, and the like.

Fig. 14 is a diagram showing response characteristics of the light receiving element 34 according to the fourth embodiment. The horizontal axis represents the distance between the light receiving element 34 and the object RF. The ratio of the distance between the first LED21-a and the light receiving element 34, the distance between the second LED21-b and the light receiving element 34, the distance between the third LED21-c and the light receiving element 34, the intensity of light emitted from the first LED21-a, the intensity of light emitted from the second LED21-b, and the intensity of light emitted from the third LED21-c is adjusted to an appropriate value.

In the response characteristic of fig. 8, the light receiving amount of the reflected light at a distance of 5[ mm ] indicates a peak. In the range of the distance greater than 5[ mm ], the amount of light received by the reflected light rapidly decreases and then increases as the distance increases. The minimum amount of reflected light remains at or above the threshold THC, but there is a risk that the minimum amount of reflected light falls below the threshold THC due to the influence of noise or the like.

In contrast, the response characteristic of fig. 14 of the present embodiment is in a range of a distance greater than 5[ mm ], and the amount of light received by the reflected light gradually decreases as the distance increases. Therefore, even if the amount of received light is affected by noise or the like, there is no risk that the amount of received light falls below the threshold THC.

In the present embodiment, the proximity sensor has 3 LEDs, but may have 4 or more LEDs. As the number of LEDs increases, the change in the amount of reflected light as a response characteristic can be made more gradual. Even when the number of LEDs is 4 or more, the intensity of infrared light emitted from an LED located close to the light receiving element 34 is lower than the intensity of infrared light emitted from an LED located far from the light receiving element 34.

[ fifth embodiment ]

Fig. 15 is a diagram showing a configuration of a proximity sensor 9 according to a fifth embodiment.

The light receiving IC11 includes: control logic 31, pulse generator 32, driver 39 including driver 233, light receiving element 34, amplifier 35, and ADC 36. The light emitting section 10 includes a first LED21 a-and a second LED 21-b.

Control logic 31 controls the driving of first LED21-a and second LED21-b in accordance with instructions from processor 13. The control logic 31 notifies the processor 13 of the presence or absence of the reception of the infrared light.

The pulse generator 32 outputs a pulse width modulation signal PWM.

The driver 233 drives the first LED21-a and the second LED21-b according to a pulse width modulation signal PWM.

The light receiving element 34 detects infrared light reflected by the object RF. The light receiving element 34 is formed of a photodiode.

The amplifier 35 amplifies the output signal of the light receiving element 34.

The ADC36 converts the output signal of the amplifier 35 into a digital signal, and outputs the digital signal to the control logic 31.

The first LED21-a and the second LED21-b are connected to a power supply VCC. The current supplied from the power supply VCC to the first LED21-a is less than the current supplied from the power supply VCC to the second LED 21-b.

More specifically, the light emitting portion 10 includes a first limiting resistance element R1 and a second limiting resistance element R2. The first limiting resistor element R1 is disposed between the power source VCC and the first LED 21-a. The second limiting resistor element R2 is disposed between the power source VCC and the second LED 21-b. The resistance value of the first limiting resistance element R1 is larger than the resistance value of the second limiting resistance element R2. Thus, the current supplied from the power supply VCC to the first LED21-a can be made smaller than the current supplied from the power supply VCC to the second LED 21-b. As a result, the intensity of the infrared light emitted from the first LED21-a can be made smaller than the intensity of the infrared light emitted from the second LED 21-b.

As described above, in the present embodiment, the first LED21-a emitting infrared light with small intensity and the second LED21-b emitting infrared light with large intensity can be driven by 1 common driver.

[ sixth embodiment ]

Fig. 16 is a diagram showing a configuration of a proximity sensor 9 according to a sixth embodiment.

The contactless sensor 9 of the sixth embodiment is different from the contactless sensor 9 of the fifth embodiment in a light emitting portion 10.

The light emitting unit 10 of the sixth embodiment includes a limiting resistance element R. The limiting resistor element R is configured between the power source VCC and the first LED 21-a. No limiting resistance element is disposed between the power supply VCC and the second LED 21-b. Thus, the current supplied from the power supply VCC to the first LED21-a can be made smaller than the current supplied from the power supply VCC to the second LED 21-b. As a result, the intensity of the infrared light emitted from the first LED21-a can be made smaller than the intensity of the infrared light emitted from the second LED 21-b.

[ seventh embodiment ]

Fig. 17 is a diagram showing a configuration of a proximity sensor 9 according to a seventh embodiment.

The contactless sensor 9 of the seventh embodiment is different from the contactless sensor 9 of the fifth embodiment in a light emitting portion 10.

The light-emitting unit 10 of the seventh embodiment includes a first limiting resistance element R1 and a second limiting resistance element R2. The first limiting resistor element R1 is disposed between the driver 233 and the first LED 21-a. The second limiting resistor element R2 is disposed between the driver 233 and the second LED 21-b. The resistance value of the first limiting resistance element R1 is larger than the resistance value of the second limiting resistance element R2. This makes it possible to reduce the current supplied from the driver 233 to the first LED21-a to be smaller than the current supplied from the driver 233 to the second LED 21-b. As a result, the intensity of the infrared light emitted from the first LED21-a can be made smaller than the intensity of the infrared light emitted from the second LED 21-b.

[ eighth embodiment ]

Fig. 18 is a diagram showing a configuration of a proximity sensor 9 according to an eighth embodiment.

The contactless sensor 9 of the eighth embodiment is different from the contactless sensor 9 of the seventh embodiment in a light emitting portion 10.

The light emitting unit 10 of the eighth embodiment includes a limiting resistance element R. The limiting resistor element R is disposed between the driver 233 and the first LED 21-a. No limiting resistance element is arranged between the driver 233 and the second LED 21-b. This makes it possible to reduce the current supplied from the driver 233 to the first LED21-a to be smaller than the current supplied from the driver 233 to the second LED 21-b. As a result, the intensity of the infrared light emitted from the first LED21-a can be made smaller than the intensity of the infrared light emitted from the second LED 21-b.

[ ninth embodiment ]

Fig. 19 is a diagram showing a configuration of a proximity sensor 9 according to a ninth embodiment.

Differences between the noncontact sensor 9 of the ninth embodiment and the noncontact sensor 9 of the first embodiment of fig. 9 will be described.

Control logic 31 controls the driving of first LED21-a and second LED21-b in accordance with instructions from processor 13. Control logic 31 controls enable signals ENa and ENb such that the timing of infrared light emitted from first LED21-a is different from the timing of infrared light emitted from second LED 21-b.

As in the first embodiment, the pulse generator 32 outputs the first pulse width modulation signal PWMa and the second pulse width modulation signal PWMb. The amplitude AP of the first pulse width modulation signal PWMa is smaller than the amplitude BP of the second pulse width modulation signal PWMb.

The first driver 33-a drives the first LED21-a in accordance with a first pulse width modulated signal PWMa. The second driver 33-b drives the second LED21-b in accordance with a second pulse width modulated signal PWMb. Since the amplitude AP of the first pulse width modulation signal PWMa is smaller than the amplitude BP of the second pulse width modulation signal PWMb, the driving unit 39 can make the intensity of the infrared light emitted from the first LED21-a smaller than the intensity of the infrared light emitted from the second LED 21-b.

The driving section 39 drives the first LED21-a and the second LED21-b at different timings. When the first LED21-a emits infrared light, the control logic 31 performs a first determination of whether or not the light receiving amount of the light receiving element 34 is equal to or greater than a first threshold value THA. When the second LED21-b emits infrared light, the control logic 31 performs a second determination of whether or not the light receiving amount of the light receiving element 34 is equal to or greater than the second threshold THB. The control logic 31 calculates the logical sum of the first determination result and the second determination result as the integrated determination result.

The control logic 31 determines that the object RF exists at a distance close to the light receiving element 34 when the integrated determination result is at the H level, and determines that the object RF exists at a distance far from the light receiving element 34 when the integrated determination result is at the L level.

Fig. 20 is a timing chart of the enable signals ENa and ENb, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb in the ninth embodiment.

At time T1, when the enable signal ENa is activated by the control logic 31, the generation of the first pulse width modulation signal PWMa of the amplitude AP of the pulse generator 32 is started at time T1.

At time T2, when the enable signal ENa is inactivated by the control logic 31, the generation of the first pulse width modulation signal PWMa by the pulse generator 32 is ended at time T2.

At time T3, when the enable signal ENb is activated by the control logic 31, the generation of the second pulse width modulated signal PWMb of the amplitude BP of the pulse generator 32 is started at time T3.

At time T4, when the enable signal ENb is inactivated by the control logic 31, the generation of the second pulse width modulation signal PWMb by the pulse generator 32 is ended at time T4.

With the above, the timing of emission of infrared light from the first LED21-a can be made different from the timing of emission of infrared light from the second LED 21-b.

Fig. 21 is a flowchart showing a procedure of an operation of the proximity sensor 9 according to the ninth embodiment. Fig. 22 is a diagram showing an example of the first determination result, the second determination result, and the integrated determination result.

In step S101, the control logic 31 sets the threshold TH to the threshold THA.

In step S102, the control logic 31 outputs the first pulse width modulation signal PWMa of the amplitude AP by activating the enable signal ENa from the pulse generator 32. This causes infrared light with a small intensity to be emitted from the first LED 21-a.

In step S103, when the light receiving amount of the light receiving element 34 is equal to or greater than the threshold TH, the process proceeds to step S104, and when the light receiving amount of the light receiving element 34 is less than the threshold TH, the process proceeds to step S105.

In step S104, the control logic 31 sets the first determination result DT1 to the H level. In step S105, the control logic 31 sets the first determination result DT1 to the L level.

Referring to fig. 4, when the distance between the object RF and the light receiving element 34 is 0 to 12mm, the light receiving amount of the light receiving element 34 is equal to or greater than the threshold TH (THA), and the first determination result is an H level. When the distance between the object RF and the light receiving element 34 is 12 to [ mm ], the amount of light received by the light receiving element 34 is less than the threshold TH (═ THA), and the first determination result is the L level.

In step S106, the control logic 31 controls not to emit infrared light from the first LED21-a by making the enable signal ENa inactive.

In step S107, the control logic 31 sets the threshold TH to the threshold THB.

In step S108, the control logic 31 outputs the second pulse width modulation signal PWMb of the amplitude BP by activating the enable signal ENb from the pulse generator 32. This causes the second LED21-b to emit infrared light having a high intensity.

In step S109, when the light receiving amount of the light receiving element 34 is equal to or greater than the threshold TH, the process proceeds to step S110, and when the light receiving amount of the light receiving element 34 is less than the threshold TH, the process proceeds to step S111.

In step S110, the control logic 31 sets the second determination result DT2 to the H level. In step S111, the control logic 31 sets the second determination result DT2 to the L level.

Referring to fig. 5, when the distance between the object RF and the light receiving element 34 is 7 to 30[ mm ], the light receiving amount of the light receiving element 34 is equal to or greater than the threshold value TH (THB), and the second determination result is the H level. When the distance between the object RF and the light receiving element 34 is 0 to 7, 30 to [ mm ], the light receiving amount of the light receiving element 34 is less than the threshold TH (═ THB), and the second determination result is the L level.

In step S112, the control logic 31 controls not to emit infrared light from the second LED21-b by making the enable signal ENb inactive.

In step S113, the control logic 31 calculates the logical sum of the first determination result DT1 and the second determination result DT2 as an integrated determination result. The overall determination result is at H level when the distances between the object RF and the light receiving element 34 are 0 to 7, 7 to 12, and 12 to 30[ mm ], and at L level when the distance between the object RF and the light receiving element 34 is 30 to [ mm ]. The control logic 31 determines that the object RF exists at a distance close to the light receiving element 34 when the integrated determination result is at the H level, and determines that the object RF exists at a distance far from the light receiving element 34 when the integrated determination result is at the L level.

[ tenth embodiment ]

A point of difference between the proximity sensor 9 of the tenth embodiment and the proximity sensor 9 of the first embodiment will be described.

Control logic 31 controls the driving of first LED21-a and second LED21-b in accordance with instructions from processor 13. As in the ninth embodiment, control logic 31 controls enable signals ENa and ENb so that the timing of infrared light emitted from first LED21-a is different from the timing of infrared light emitted from second LED 21-b.

The pulse generator 32 outputs a first pulse width modulation signal PWMa and a second pulse width modulation signal PWMb. The amplitude of the first pulse width modulation signal PWMa is equal to the amplitude of the second pulse width modulation signal PWMb.

The first driver 33-a drives the first LED21-a in accordance with a first pulse width modulated signal PWMa. The second driver 33-b drives the second LED21-b in accordance with a second pulse width modulated signal PWMb. Since the amplitude of the first pulse width modulation signal PWMa is the same as the amplitude of the second pulse width modulation signal PWMb, the driving unit 39 can make the intensity of the infrared light emitted from the first LED21-a the same as the intensity of the infrared light emitted from the second LED 21-b.

The driving unit 39 drives the first LED21-a and the second LED21-b at different timings, as in the ninth embodiment. When the first LED21-a emits infrared light, the control logic 31 performs a first determination of whether or not the light receiving amount of the light receiving element 34 is equal to or greater than a first threshold THA 2. When the second LED21-b emits infrared light, the control logic 31 performs a second determination of whether or not the light receiving amount of the light receiving element 34 is equal to or greater than a second threshold THB 2. The control logic 31 calculates the logical sum of the first determination result and the second determination result as the integrated determination result.

The control logic 31 determines that the object RF exists at a distance close to the light receiving element 34 when the integrated determination result is at the H level, and determines that the object RF exists at a distance far from the light receiving element 34 when the integrated determination result is at the L level.

Fig. 23 is a timing chart of the enable signals ENa and ENb, the first pulse width modulation signal PWMa, and the second pulse width modulation signal PWMb in the tenth embodiment.

At a time T1, when the enable signal ENa is activated by the control logic 31, the generation of the first pulse width modulation signal PWMa of the amplitude P of the pulse generator 32 is started at a time T1.

At time T2, when the enable signal ENa is inactivated by the control logic 31, the generation of the first pulse width modulation signal PWMa by the pulse generator 32 is ended at time T2.

At time T3, when the enable signal ENb is activated by the control logic 31, the generation of the second pulse width modulated signal PWMb of amplitude P of the pulse generator 32 is started at time T3.

At time T4, when the enable signal ENb is inactivated by the control logic 31, the generation of the second pulse width modulation signal PWMb by the pulse generator 32 is ended at time T4.

With the above, the timing of emission of infrared light from the first LED21-a can be made different from the timing of emission of infrared light from the second LED 21-b.

Fig. 24 is a flowchart showing a procedure of the operation of the proximity sensor 9 according to the tenth embodiment.

In step S201, the control logic 31 sets the threshold TH to the threshold THA 2.

In step S202, the control logic 31 outputs the pulse width modulation signal PWMa of the amplitude P by activating the enable signal ENa from the pulse generator 32. This causes infrared light to be emitted from the first LED 21-a.

In step S203, when the light receiving amount of the light receiving element 34 is equal to or greater than the threshold TH, the process proceeds to step S204, and when the light receiving amount of the light receiving element 34 is less than the threshold TH, the process proceeds to step S205.

In step S204, the control logic 31 sets the first determination result DT1 to the H level. In step S205, the control logic 31 sets the first determination result DT1 to the L level.

In step S206, the control logic 31 controls not to emit infrared light from the first LED21-a by making the enable signal ENa inactive.

In step S207, the control logic 31 sets the threshold TH to the threshold THB 2.

In step S208, the control logic 31 outputs the pulse width modulation signal PWMb of the amplitude P by activating the enable signal ENb from the pulse generator 32. Thus, infrared light of the same intensity as that emitted from the first LED21-b is emitted from the second LED 21-a.

In step S209, when the light receiving amount of the light receiving element 34 is equal to or greater than the threshold TH, the process proceeds to step S210, and when the light receiving amount of the light receiving element 34 is smaller than the threshold TH, the process proceeds to step S211.

In step S210, the control logic 31 sets the second determination result DT2 to the H level. In step S211, the control logic 31 sets the second determination result DT2 to the L level.

In step S212, the control logic 31 controls not to emit infrared light from the second LED21-b by making the enable signal ENb inactive.

In step S213, the control logic 31 calculates the logical sum of the first determination result DT1 and the second determination result DT2 as the integrated determination result DT.

(modification example)

The present invention is not limited to the above-described embodiments, and includes the following modifications, for example.

(1) Instead of the LED, a vcsel (vertical Cavity Surface Emitting laser) may be used.

(2) The LED emits infrared light, and the light receiving element detects the infrared light. For example, visible light or near-infrared light may be emitted from the LED, and the light receiving element may detect the visible light or near-infrared light.

The embodiments of the present invention have been described, but the embodiments disclosed herein are not intended to be limiting in all respects. The scope of the present invention is shown by the claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.