1. A sensor circuit for heating or detecting a liquid level; it is characterized by comprising:

the power supply circuit comprises a comparator, a heating branch circuit, a diode circuit, a selection circuit and a cascade circuit, wherein the comparator and the heating branch circuit are respectively connected with the cascade circuit, and the diode circuit is electrically connected with the selection circuit;

the control circuit is electrically connected with the selection circuit and is used for controlling the work of the selection circuit so as to enable the diode circuit to be directly and electrically connected with the cascade circuit or the heating branch circuit;

and the sensing circuit is electrically connected with the cascade circuit and is used for outputting a liquid level signal of the liquid.

2. The sensor circuit of claim 1, wherein the cascade circuit comprises a primary circuit, a secondary circuit and a tertiary circuit connected in parallel, the comparator is electrically connected to the primary circuit, the secondary circuit and the tertiary circuit respectively, the state of the primary circuit, the secondary circuit and the tertiary circuit is controlled by the voltage input to the comparator, the sensing circuit is electrically connected to the tertiary circuit, and the diode circuit is directly electrically connected to the secondary circuit or electrically connected to the heating branch.

3. The sensor circuit of claim 2, wherein the tertiary circuit comprises a current output interface and a voltage output interface, the sensing circuit comprises a first sensing diode branch, a second sensing diode branch, and an amplification circuit, the first sensing diode branch and the second sensing diode branch are connected in parallel, the first sensing diode branch is connected to the current output interface, and the amplification circuit is connected to the first sensing diode branch and the second sensing diode branch.

4. The sensor circuit of claim 2, wherein the heating branch is electrically connected to the tertiary circuit, the selection circuit comprises a second selection circuit, the diode circuit is electrically connected to the second selection circuit, and the control circuit is electrically connected to the second selection circuit for controlling the second selection circuit to be connected to the secondary circuit or to be electrically connected to the heating branch.

5. The sensor circuit of claim 2, wherein the heating branch is electrically connected to the secondary circuit, the selection circuit comprises a first selection circuit, the diode circuit is electrically connected to the first selection circuit, and the control circuit is electrically connected to the first selection circuit for controlling the first selection circuit to be directly electrically connected to the secondary circuit or to be electrically connected to the heating branch.

6. The sensor circuit of claim 5, wherein the secondary circuit comprises a current mirror circuit, a resistor R2 and a resistor R3, the resistor R2 and the resistor R3 are connected in parallel and then electrically connected to the current mirror circuit, the heating branch is connected in parallel to the resistor R2, and the control circuit is configured to control the first selection circuit to be electrically connected to the heating branch or the resistor R2.

7. The MCU liquid level sensor is applied to liquid level detection of a cavity and is characterized by comprising an MCU chip and a plurality of detection circuits, wherein each detection circuit comprises a power supply circuit and a sensing circuit, the detection circuits are respectively arranged at different heights in the cavity, and the MCU chip is electrically connected with the detection circuits and used for controlling heating or liquid level measurement of the detection circuits and determining the medium environment where the detection circuits are located according to signals output by the detection circuits so as to determine the liquid level.

8. The MCU liquid level sensor according to claim 7, wherein the power supply circuit comprises a comparator, a heating branch circuit, a diode circuit, a selection circuit and a cascade circuit, the comparator and the heating branch circuit are respectively connected with the cascade circuit, the diode circuit is electrically connected with the selection circuit, the MCU chip controls the selection circuit to work so as to switch the diode circuit to be electrically connected with the heating branch circuit or directly electrically connected with the cascade circuit, and the sensing circuit is electrically connected with the cascade circuit and used for outputting a liquid level signal of liquid.

9. The MCU liquid level sensor of claim 7, further comprising a computing circuit electrically connected to the detection circuit and the MCU chip, respectively, for converting the signal output by the detection circuit into a digital signal and inputting the digital signal into the MCU chip.

10. An ink cartridge comprising a cartridge body and a sensor circuit according to any one of claims 1 to 6, wherein the sensor circuit is detachably provided in the cartridge body.

Background

The sensors commonly used for measuring the liquid level position, such as an ultrasonic sensor, a float-type liquid level sensor, a floating ball-type liquid level sensor, a static pressure-type liquid level sensor and the like, have the problems of large volume and high cost.

In order to solve the problems of volume and cost, the prior art designs two modes of heating liquid and detecting liquid level, one is to design a special heating circuit and a special detection circuit, so that the liquid is heated by the heating circuit, and the liquid level is detected by the detection circuit.

The other is to arrange the heater and the sensor in the same circuit, as shown in fig. 1 and 2, a column of the heater 10 and the sensor 20 is arranged along the height direction of the liquid level, wherein the heater 10 and the sensor 20 are arranged at intervals, so that the liquid is heated by the heater 10, and the liquid level height of the liquid is detected by the sensor 20.

Disclosure of Invention

In order to overcome the problems existing in the prior art, the present application mainly aims to provide a sensor circuit which can simultaneously realize the heating and detecting functions by using one set of control circuit, and has the advantages of flexible control, small volume and low cost.

In order to achieve the above purpose, the following technical solutions are specifically adopted in the present application:

the present application provides a sensor circuit for heating or detecting a liquid level; the sensor circuit includes:

the power supply circuit comprises a comparator, a heating branch circuit, a diode circuit, a selection circuit and a cascade circuit, wherein the comparator and the heating branch circuit are respectively connected with the cascade circuit, and the diode circuit is electrically connected with the selection circuit;

the control circuit is electrically connected with the selection circuit and is used for controlling the work of the selection circuit so as to enable the diode circuit to be directly and electrically connected with the cascade circuit or the heating branch circuit;

and the sensing circuit is electrically connected with the cascade circuit and is used for outputting a liquid level signal of the liquid.

In a specific embodiment, the cascade circuit includes a first stage circuit, a second stage circuit, and a third stage circuit connected in parallel, the comparator is electrically connected to the first stage circuit, the second stage circuit, and the third stage circuit, the states of the first stage circuit, the second stage circuit, and the third stage circuit are controlled by the voltage input to the comparator, the sensing circuit is electrically connected to the third stage circuit, and the diode circuit is directly electrically connected to the second stage circuit or electrically connected to the heating branch.

In a specific embodiment, the heating branch is electrically connected to the secondary circuit, the selection circuit includes a first selection circuit, the diode circuit is electrically connected to the first selection circuit, and the control circuit is electrically connected to the first selection circuit and is configured to control the first selection circuit to be directly electrically connected to the secondary circuit or to be electrically connected to the heating branch.

In a specific embodiment, the secondary circuit includes a MOS transistor Q2, a resistor R2, and a resistor R3, the resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2, the heating branch is connected in parallel with the resistor R2, and the control circuit is configured to control the first selection circuit to be electrically connected to the heating circuit or the resistor R2.

In a specific embodiment, the secondary circuit includes a current mirror circuit, a resistor R2 and a resistor R3, the resistor R2 and the resistor R3 are connected in parallel and then electrically connected to the current mirror circuit, the heating branch is connected in parallel to the resistor R2, and the control circuit is configured to control the first selection circuit to be electrically connected to the heating branch or the resistor R2.

In a specific embodiment, the selection circuit includes a fourth selection circuit, the current mirror circuit includes at least two MOS transistor branches connected in parallel, each MOS transistor branch is connected to an input power source through the fourth selection circuit, and the fourth selection circuit is electrically connected to the control circuit, and the control circuit controls the operation of the fourth selection circuit to switch each MOS transistor branch to be connected to the input power source.

In a specific embodiment, the heating branch circuit is electrically connected to the tertiary circuit, the selection circuit includes a second selection circuit, the diode circuit is electrically connected to the second selection circuit, and the control circuit is electrically connected to the second selection circuit for controlling the second selection circuit to be connected to the secondary circuit or to be electrically connected to the heating branch circuit.

In a specific embodiment, the three-stage circuit includes a MOS transistor Q3 and a resistor R4, the MOS transistor Q3 is connected in series with the resistor R4, and the heating branch is connected to the resistor R4.

In a specific embodiment, the three-stage circuit includes a current mirror circuit and a resistor R4, the resistor R4 is connected in series with the current mirror circuit, and the heating branch is connected in parallel with the resistor R4.

In a specific embodiment, the selection circuit includes a fifth selection circuit, the current mirror circuit includes at least two MOS transistor branches connected in parallel, each MOS transistor branch is connected to an input power source through the fifth selection circuit, and the fifth selection circuit is electrically connected to the control circuit, and the control circuit controls the operation of the fifth selection circuit to switch each MOS transistor branch to be connected to the input power source.

In a specific embodiment, the heating branch circuit is electrically connected to the primary circuit, the selection circuit includes a third selection circuit, the diode circuit is electrically connected to the third selection circuit, and the control circuit is electrically connected to the third selection circuit and is configured to control the third selection circuit to be electrically connected to the secondary circuit or to the heating branch circuit.

In a specific embodiment, the primary circuit includes a MOS transistor Q1, a resistor R1, and a diode D0, the resistor R1 is connected in parallel with the diode D0 and then connected in series with the MOS transistor Q1, and the heating branch is connected in parallel with the diode D0.

In a specific embodiment, the three-stage circuit includes a current mirror circuit, a resistor R1 and a diode D0, the resistor R1 is connected in parallel with the diode D0 and then connected in series with the current mirror circuit, and the heating branch is connected in parallel with the diode D0.

In a specific embodiment, the selection circuit includes a sixth selection circuit, the current mirror circuit includes at least two MOS transistor branches connected in parallel, each MOS transistor branch is connected to an input power source through the sixth selection circuit, and the sixth selection circuit is electrically connected to the control circuit, and the control circuit controls the operation of the sixth selection circuit to switch each MOS transistor branch to be connected to the input power source.

In a specific embodiment, the sensing circuit is electrically connected to the control circuit, and the control circuit is configured to control the diode circuit to be electrically connected to the heating branch or directly connected to the secondary circuit according to an output result of the sensing circuit.

In a specific embodiment, the three-stage circuit includes a current output interface and a voltage output interface, the sensing circuit includes a first sensing diode branch, a second sensing diode branch, and an amplifying circuit, the first sensing diode branch and the second sensing diode branch are connected in parallel, the first sensing diode branch is connected to the current output interface, and the amplifying circuit is connected to the first sensing diode branch and the second sensing diode branch.

Correspondingly, this application still provides an MCU level sensor, is applied to the liquid level detection in the cavity, MCU level sensor includes MCU chip and a plurality of detection circuitry, detection circuitry includes power supply circuit and sensing circuit, and is a plurality of detection circuitry set up respectively in different heights in the cavity, MCU chip electricity connect in each detection circuitry for control each detection circuitry's heating or level measurement, and according to the signal determination of detection circuitry output the medium environment that detection circuitry was located, in order to confirm the liquid level.

In a specific implementation manner, the power circuit includes a comparator, a heating branch, a diode circuit, a selection circuit, and a cascade circuit, the comparator and the heating branch are respectively connected to the cascade circuit, the diode circuit is electrically connected to the selection circuit, the selection circuit is controlled by the MCU chip to operate so as to switch the diode circuit to be electrically connected to the heating branch or directly electrically connected to the cascade circuit, and the sensing circuit is electrically connected to the cascade circuit for outputting a liquid level signal of the liquid.

In a specific implementation manner, the power circuit includes a comparator, a heating branch, a diode circuit, a selection circuit, and a cascade circuit, the comparator and the heating branch are respectively connected to the cascade circuit, the diode circuit is electrically connected to the selection circuit, the selection circuit is controlled by the MCU chip to operate so as to switch the diode circuit to be electrically connected to the heating branch or directly electrically connected to the cascade circuit, and the sensing circuit is electrically connected to the cascade circuit for outputting a liquid level signal of the liquid.

In a specific embodiment, the cascade circuit includes a first stage circuit, a second stage circuit and a third stage circuit connected in parallel, the comparator is electrically connected to the first stage circuit, the second stage circuit and the third stage circuit respectively, the sensing circuit is electrically connected to the third stage circuit, the heating branch is electrically connected to the first stage circuit, the second stage circuit or the third stage circuit, and the MCU chip is configured to control the diode circuit to be electrically connected to the heating branch or directly connected to the second stage circuit.

In a specific implementation manner, the MCU liquid level sensor further includes a calculating circuit, and the calculating circuit is electrically connected to the detecting circuit and the MCU chip respectively, and is configured to convert the signal output by the detecting circuit into a digital signal and input the digital signal into the MCU chip.

Correspondingly, the application also provides an ink box which comprises a box body and the sensor circuit, wherein the sensor circuit is detachably arranged on the box body.

Compare in prior art, the sensor circuit of this application includes power supply circuit, control circuit and sensing circuit, when the liquid is heated to needs, makes diode circuit switch-on heating branch road through control circuit control selection circuit to generate heat the liquid through diode circuit, realize the heating function. When the liquid level of the liquid needs to be detected, the control circuit controls the selection circuit to enable the cascade circuit to be directly connected with the diode circuit, so that the liquid level of the liquid is detected through output signals of the power circuit, the control circuit and the sensing circuit, and the liquid level detection function is achieved. The control mode is flexible, one set of control circuit can control the heating and liquid level detection functions simultaneously, the circuit structure is simplified, and the cost is saved.

Drawings

FIG. 1 is a schematic view of a portion of a prior art liquid level detection apparatus.

Fig. 2 is a partial circuit diagram of the liquid level detection apparatus of fig. 1.

Fig. 3 is a circuit diagram of a sensor circuit provided in embodiment 1 of the present application.

Fig. 3A is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 1 of the present application.

Fig. 3B is a circuit diagram of a sensing circuit in the sensor circuit provided in embodiment 1 of the present application.

Fig. 4 is a schematic diagram of the corresponding relationship between voltage and temperature in embodiment 1 of the present application.

Table 1 is a table of the correspondence between the ratio u and the temperature.

Table 2 is a table of the correspondence between the ratio u and the temperature in the air medium.

Table 3 shows a table of the correlation between the ratio u and the temperature in the ink medium.

Fig. 5 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 2 of the present application.

Fig. 6 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 3 of the present application.

Fig. 7 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 5 of the present application.

Fig. 8 is a schematic block diagram of a chip and a detection circuit provided in embodiment 7 of the present application.

Fig. 9 is a schematic block diagram of an ink cartridge provided in example 8 of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless specified or indicated otherwise; the terms "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, integrally connected, or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In the description of the present application, it should be understood that the terms "upper" and "lower" used in the description of the embodiments of the present application are used in a descriptive sense only and not for purposes of limitation. In addition, in this context, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on "or" under "the other element or be indirectly on" or "under" the other element via an intermediate element.

Example 1

Referring to fig. 3 and fig. 3A, fig. 3 is a sensor circuit provided in an embodiment of the present application, and fig. 3A is a circuit diagram of a power supply circuit 301 in the sensor circuit in fig. 3. A sensor circuit for heating or detecting a level of a liquid, the sensor circuit comprising: a power supply circuit 301, a control circuit 305 and a sensing circuit 302, the power supply circuit 301 comprising a comparator U1, a heating branch L, a diode circuit 304, a first selection circuit 303 and a cascade circuit. The comparator U1 and the heating branch L are connected to the cascade circuit, and the diode circuit 304 is electrically connected to the first selection circuit 303. The control circuit 305 is electrically connected to the first selection circuit 303, and is configured to control the operation of the first selection circuit 303, so that the diode circuit 304 is electrically connected to the cascade circuit directly or to the heating branch L.

Specifically, the cascade circuit includes a primary circuit 306, a secondary circuit 307 and a tertiary circuit 308, the primary circuit 306 includes a MOS transistor Q1, a resistor R1 and a diode D0, wherein the resistor R1 is connected in parallel with the diode D0, and then connected in series with the MOS transistor Q1. The secondary circuit 307 comprises a MOS transistor Q2, a resistor R2 and a resistor R3, the resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2, and the heating branch L is connected in parallel with the resistor R2. The third-stage circuit 308 comprises an MOS transistor Q3, a resistor R4, a current output interface and a voltage output interface, the MOS transistor Q3 is connected in series with the resistor R4, and the current output interface and the voltage output interface are connected to a source electrode of the MOS transistor Q3, wherein the current output interface is used for outputting current Iref, the voltage output interface is used for outputting voltage Vref, the output current Iref is used for driving the sensing circuit 302, and the output voltage Vref is used for measuring liquid level parameters. The diode circuit 304 includes a plurality of diodes D1, D2 … … DN connected in parallel, for example, 10 diodes in parallel, and the diode circuit 304 is electrically connected to the first selection circuit 305.

Further, the resistances of the resistors in the primary circuit 306, the secondary circuit 307 and the tertiary circuit 308 are the same, and the sizes of the MOS transistor Q1, the MOS transistor Q2 and the MOS transistor Q3 are the same.

The drain electrodes of the MOS tube Q1, the MOS tube Q2 and the MOS tube Q3 are connected with an input power VCC, the comparator U1 comprises an input end Va and an input end Vb, the output end of the comparator U1 is electrically connected with the grid electrodes of the MOS tube Q1, the MOS tube Q2 and the MOS tube Q3 respectively, and the working state of each MOS tube is controlled by controlling the voltage flowing into the input end Va and the input end Vb of the comparator U1.

The heating branch L is connected in parallel with the resistor R2 in the secondary circuit, and the first selection circuit 303 is controlled by the control circuit 305 to selectively switch on the heating branch L or the resistor R2 in the secondary circuit.

The control circuit 305 is connected to the first selection circuit 303, and controls the first selection circuit 303 to turn on the heating branch L or turn on the secondary circuit 307, specifically, the control circuit 305 may load a preset program to control the first selection circuit 303 to turn on the heating branch L or turn on the secondary circuit 307 at a certain time interval, for example, two minutes.

When the first selection circuit 303 is electrically connected to the heating branch L, a specific current may be input to the diode circuit 304, so that the diode circuit 304 generates heat to realize a heating function; when the first selection circuit 303 is electrically connected to the resistor R2 in the secondary circuit 307, i.e. the diode circuit 304 is electrically connected to the secondary circuit 307, the power circuit outputs a stable voltage Vref for determining the liquid level parameter.

Generally, when the voltage of the diode is less than 0.8V, the internal resistance of the diode changes, the heating power dynamically changes according to the difference of the diode, and when the voltage is more than 0.8V, the voltage of the diode is basically unchanged under a certain large current, the corresponding heating power P is I × V (I is the current, V is the voltage), and at this time, the heating power of the diode is determined by the heating current.

In order to facilitate the control of the heating duration of the diode circuit according to the current magnitude of the heating branch, the sensor circuit further comprises a feedback circuit, the feedback circuit is electrically connected with the heating branch and the control circuit respectively, and the feedback circuit is used for feeding back the current magnitude of the heating branch, so that the control circuit can control the duration of the diode circuit being connected with the heating branch according to the current magnitude of the heating branch fed back by the feedback circuit, namely, the heating duration of the diode circuit is controlled.

The heating time of the diode circuit is related to the magnitude of the heating current I2c (current of the heating branch), and the heating time of the diode circuit can be relatively reduced when the heating current I2c is larger. For example, when the heating current I2c is 1A, the heating time of the diode circuit is 5 minutes, and when the heating current I2c is 500mA, the heating time of the diode circuit is 10 minutes.

In another embodiment, in order to increase the heating power, a plurality of dummy (resistors unrelated to circuit matching) may be further provided in the diode circuit, for example, several or several tens of dummy may be provided, and the dummy is also controlled by a switch to satisfy the heating power of the diode circuit.

Referring to fig. 3B, a circuit diagram of a sensing circuit in a sensor circuit according to an embodiment of the present application is shown. Sensing circuit 302 includes a first sense diode branch 401, a second sense diode branch 402, and an amplification circuit 403, first sense diode branch 401 including a first diode a, and second sense diode circuit 402 including a second diode B. The first sensing diode branch 401 and the second sensing diode branch 402 are connected in parallel, and the current output interface of the power circuit 301 is respectively connected to the first sensing diode branch 401 and the second sensing diode branch 402. The amplifying circuit 403 is connected to the first sensing diode branch 401 and the second sensing diode branch 402, and is configured to amplify a voltage difference between the first sensing diode branch 401 and the second sensing diode branch 402, an output end of the amplifying circuit 403 is configured to output the amplified voltage difference, and the voltage difference output by the amplifying circuit 403 and a voltage output by a voltage output interface of the power circuit 301 may be used to subsequently calculate corresponding liquid level information.

In addition, the control circuit 305 may be connected to the output terminal of the sensing circuit 302, and control the first selection circuit 303 to turn on the heating branch L or turn on the secondary circuit 307 according to the output result of the sampling sensing circuit 302.

Fig. 4 is a schematic diagram showing the voltage variation with temperature. The voltage comprises an output voltage Vref of the power supply circuit, a diode voltage in the second sensing diode branch, an output voltage of an amplifier in the sensing circuit, and a voltage difference between the first sensing diode branch and the second sensing diode branch, and is shown along with the temperature change. When Va is controlled to be Vb, the MOS transistor Q1, the MOS transistor Q2, and the MOS transistor Q3 are connected to the same node, and the current I1 flowing in the primary circuit, the current I2 flowing in the secondary circuit, and the current I3 flowing in the tertiary circuit are equal to each other according to the principle of the current mirror circuit; the current I1a flowing into the diode in the primary circuit is equal to the current I2a flowing into the resistor R2 of the secondary circuit; the current I1b flowing into the resistor in the primary circuit is equal to the current I2b flowing into the resistor R3 in the secondary circuit; the output voltage of the power circuit is determined by the resistance ratio in the primary circuit, the secondary circuit and the tertiary circuit; the magnitude Iref of the output current is equal to the magnitude I1 of the inflow current of the primary circuit; the magnitude of the inflow current I1 of the primary circuit, the magnitude of the inflow current I2 of the secondary circuit and the magnitude of the inflow current I3 of the tertiary circuit are equal; the magnitude of the current i1 flowing into the first sensing diode branch is equal to the magnitude Iref of the output current, the current flowing into the second sensing diode branch is equal to five times of the current flowing into the first sensing diode branch, and the ratio of the voltage drop VB across the second diode B to the voltage difference Δ VB between the first sensing diode branch and the second sensing diode branch is related to the magnitude of the current flowing into the sensing circuit, i.e. the sensing circuit can be designed according to the current flowing into the sensing circuit. The ambient temperature affects the differential pressure Δ VB, as shown in fig. 4, the higher the temperature is, the larger the differential pressure Δ VB is, the larger the output voltage of the amplifier in the sensing circuit is; and determining u according to the voltage difference delta VB between the first sensing diode branch and the second sensing diode branch, the amplification factor of the amplifier and the ratio of the output voltage Vref of the power supply circuit, wherein the ratio u is different under different heating temperatures and medium environments, namely the medium environment can be determined according to the ratio u when the heating temperature is constant, or the heating temperature can be determined according to the ratio u when the medium environment is constant. The output voltage Vref is determined by the resistance ratio of the resistor R2, the resistor R3, and the resistor R4, and the resistances of the resistor R2, the resistor R3, and the resistor R4 have little influence on the output voltage Vref.

For example: the relation of the ratio u in the ink environment is:

u＝(M1*α*△VB/Vref)+N1

specific fitting relationship example: u ═ 0.56 ×. α Δ VB/Vref) + 24.

Wherein alpha is the amplification factor of the amplifying circuit, delta VB is the voltage difference of the sensing circuit, Vref is the output voltage of the power circuit, M1 is the slope, N1 is the intercept, the relation u fitted by multiple tests is a linear relation, and the specific M1 and N1 can be fitted and determined by multiple groups of test data.

The relation of the ratio u in the gas medium environment is as follows:

u＝(M2*α*△VB/Vref)+N2

specific fitting relationship example: u ═ 0.48 ×. α Δ VB/Vref) + 28.

Wherein alpha is the amplification factor of the amplifying circuit, delta VB is the voltage difference of the sensing circuit, Vref is the output voltage of the power circuit, M2 is the slope, N2 is the intercept, the relation u fitted by multiple tests is a linear relation, and the specific M2 and N2 can be fitted and determined by multiple groups of test data.

The ratio u is in different media, and the corresponding relation between the voltage difference delta VB and the output voltage Vref of the power circuit is different; the ratio u and the heating temperature have a corresponding relation, and the higher the heating temperature is, the larger the ratio u is in the same medium environment; in different medium environments, the same ratio u corresponds to different medium environment temperatures.

In different media, the corresponding relation of the ratio u between the voltage difference Δ VB and the output voltage Vref of the power circuit is different, as shown in table 1, according to the relation between the ratio u and the air medium, a specific corresponding relation can be established to form a ratio u corresponding table, the amplification factor of the amplification circuit to the voltage difference Δ VB is set to be 16, the output voltage Vref is set to be 1.28V, when the measured voltage difference Δ VB is 2mV, the ratio u in the corresponding air medium is 40.12, and the ratio u in the corresponding ink medium is 38.3; when the measured voltage difference delta VB is 3mV, the ratio u in the corresponding air medium is 46.3, and the ratio u in the corresponding ink medium is 45.2; when the measured voltage difference Δ VB is 4mV, the ratio u in the air medium is 51.8, and the ratio u in the ink medium is 49.5.

Changing the output voltage of the output voltage Vref to 1.22V, keeping the amplification factor of the amplifying circuit to the voltage difference DeltaVB unchanged to 16, and when the measured voltage difference DeltaVB is 6mV, the ratio u in the corresponding air medium is 65.55, and the ratio u in the corresponding ink medium is 68.09; when the measured voltage difference delta VB is 8mV, the ratio u in the corresponding air medium is 78.3, and the ratio u in the corresponding ink medium is 87.78; when the measured voltage difference Δ VB is 10mV, the ratio u in the corresponding air medium is 90.93, and the ratio u in the corresponding air medium is 97.34.

Changing the output voltage of Vref to 1.20V, keeping the amplification factor of the amplifying circuit to the voltage difference DeltaVB unchanged to 16, and when the measured voltage difference DeltaVB is 8mV, the ratio u in the corresponding air medium is 79.22, and the ratio u in the corresponding ink medium is 83.68; when the measured voltage difference Δ VB is 9mV, the ratio u in the air medium is 85.61, and the ratio u in the ink medium is 91.15.

The ratio u has a corresponding relation with the heating temperature, and the higher the heating temperature is, the larger the ratio u is in the same medium environment; in different medium environments, the same ratio u corresponds to different medium environment temperatures, and as shown in tables 2 and 3, when the ratio u in the air medium is 40.12, 46.3, 51.8, 65.55, 78.30, 90.93 and 79.22, the ratio u in the air medium corresponds to the heating temperature of the diode circuit, 32.4 ℃, 36.2 ℃, 37 ℃, 45.4 ℃, 51.6 ℃, 68.2 ℃, 75.6 ℃ and 79 ℃; when the ratio u in the ink medium is 38.3, 45.2, 49.5, 68.09, 87.78, 97.34, 83.68, 91.15, the heating temperature of the diode circuit is 33.2 ℃, 38.5 ℃, 41 ℃, 47 ℃, 56.5 ℃, 72 ℃, 78.7 ℃ and 82.3 ℃.

In summary, the temperature can be determined according to the heating of the diode, the ratio u2 obtained by calculating the ratio of the corresponding ratio u1, the voltage difference delta VB and the output voltage Vref is determined according to the temperature, the medium environment where the device is located is determined according to the ratio u1 and the ratio u2, and the liquid level information can be measured according to a plurality of sensor circuits, for example, the height of the device to be measured is h, 2 sensor circuits are designed at equal intervals, and when the 2 sensor circuits are detected to be located in the liquid medium, the liquid level can be judged to be more than 2/3h of the device to be measured; when the sensor circuit arranged below is detected to be in the liquid medium and the sensor circuit arranged above is detected to be in the air medium, the liquid level can be judged to be between 1/3h and 2/3h of the device to be detected; when 2 sensor circuits are detected to be in the air medium, the liquid level can be judged to be below 1/3h of the device to be tested.

Example 2

Based on embodiment 1, the present application further discloses another specific implementation manner, and referring to fig. 5, fig. 5 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 2 of the present application, and this embodiment is different from the above embodiments in that in this embodiment, the secondary circuit includes a fourth selection circuit, a current mirror circuit and a resistor, the fourth selection circuit is connected with the current mirror circuit, and the current mirror circuit is connected with the resistor in series. Specifically, the current mirror circuit comprises an MOS transistor Q2 branch and an MOS transistor Q2' branch which are connected in parallel, each of the MOS transistor branches is connected to the input power VCC through a fourth selection circuit, and the fourth selection circuit is electrically connected to the control circuit, and the control circuit controls the fourth selection circuit to operate so as to switch each of the MOS transistor branches to be connected to the input power VCC.

In this embodiment, the MOS transistors Q2 and Q2' have different W/L (width-to-length ratios) so that the currents flowing through the respective MOS transistor branches are different after the input power VCC is turned on, and the magnitude of the output current of the heating branch is controlled so that the respective MOS transistor branches output different current values after the input power VCC is turned on.

The rest of the structure is the same as the circuit of embodiment 1, and is not described again.

Example 3

Based on the foregoing embodiment 1, the present application further discloses another specific implementation manner, and referring to fig. 6, fig. 6 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 3 of the present application. The difference between this embodiment and embodiment 1 is that, in this embodiment, the secondary circuit includes a MOS transistor Q2, a resistor R2, and a resistor R3, and the resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2; the three-stage circuit comprises a MOS transistor Q3, a resistor R4, a current output interface and a voltage output interface. The MOS transistor Q3 and the resistor R4 are connected in series, the resistor R4 and the heating branch circuit L are connected in parallel, the source output of the MOS transistor Q3 is connected with a current output interface and a voltage output interface, the current output interface is used for outputting current Iref, and the voltage output interface is used for outputting voltage Vref. The diode circuit is electrically connected with the second selection circuit, and the control circuit is connected with the second selection circuit and controls the second selection circuit to be connected with the heating branch circuit L or the secondary circuit.

Furthermore, the control circuit can load a preset program and control the second selection circuit to switch on the heating branch or the secondary circuit at a certain time interval, such as 2 minutes; in addition, the control circuit can be connected with the sensing circuit, and the second selection circuit is controlled to be connected with the heating branch circuit or the secondary circuit according to the sensing result of the sensing circuit.

Example 4

Based on embodiment 3, the present application further discloses another specific implementation manner, and a difference between this embodiment and embodiment 3 is that in this embodiment, the three-stage circuit may further include a fifth selection circuit, a current mirror circuit, and a resistor, where the fifth selection circuit is connected to the current mirror circuit, the current mirror circuit is connected to the current output interface and the voltage output interface, and the current output interface and the voltage output interface are connected to the resistor. Specifically, the current mirror circuit comprises at least two parallel MOS tube branches, each MOS tube branch is connected to the input power supply through a fifth selection circuit, the fifth selection circuit is electrically connected to the control circuit, and the control circuit controls the operation of the fifth selection circuit to switch each MOS tube branch to be connected to the input power supply, so that each MOS tube branch outputs different current values after the input power supply is connected.

In this embodiment, the MOS transistors of the respective MOS transistor branches have different W/L (width-to-length ratios) so that the currents flowing through the respective MOS transistor branches are different after the input power supply is turned on, and further, the magnitude of the output current of the heating branch is controlled so that the respective MOS transistor branches output different current values after the input power supply is turned on.

The rest is the same as the sensor circuit of embodiment 3, and the description is omitted.

Example 5

Based on the foregoing embodiment 1, the present application further discloses another specific implementation manner, and referring to fig. 7, fig. 7 is a circuit diagram of a power supply circuit in a sensor circuit provided in embodiment 5 of the present application. The present embodiment is different from embodiment 1 described above in that, in the present embodiment, the primary circuit includes a MOS transistor Q1, a resistor R1, and a diode D0. The resistor R1 is connected with the diode D0 in parallel and then connected with the MOS tube Q1 in series, and the heating branch L is connected with the diode D0 in parallel; the secondary circuit comprises a MOS transistor Q2, a resistor R2 and a resistor R3, wherein the resistor R2 is connected with the resistor R3 in parallel and then connected with the MOS transistor Q2 in series. The diode circuit is connected with the third selection circuit, the control circuit is connected with the third selection circuit, and the third selection circuit is controlled to be connected with the heating branch circuit or the secondary circuit.

Furthermore, the control circuit can load a preset program and control the third selection circuit to switch on the heating branch or the secondary circuit at a certain time interval, such as 2 minutes; in addition, the control circuit can be connected with the sensing circuit, and controls the third selection circuit to switch on the heating branch circuit or switch on the secondary circuit according to the sensing result of the sensing circuit.

Example 6

Based on embodiment 5, the present application further discloses another specific implementation manner, and the difference between this embodiment and embodiment 5 is that in this embodiment, the primary circuit may further include a sixth selection circuit, a current mirror circuit, a resistor, and a diode; the resistor and the diode are connected in parallel and then connected in series with the current mirror circuit, the current mirror circuit is connected with the sixth selection circuit, and the comparator is connected with the current mirror circuit. Specifically, the current mirror circuit comprises at least two MOS tube branches connected in parallel, each MOS tube branch is connected to the input power supply through a sixth selection circuit, the sixth selection circuit is electrically connected to the control circuit, and the control circuit controls the operation of the sixth selection circuit to switch each MOS tube branch to be connected to the input power supply.

In this embodiment, the MOS transistors of the respective MOS transistor branches have different W/L (width-to-length ratios) so that the currents flowing through the respective MOS transistor branches are different after the input power supply is turned on, and further, the magnitude of the output current of the heating branch is controlled so that the respective MOS transistor branches output different current values after the input power supply is turned on.

The rest of the sensor circuits are the same as those of the sensor circuits in embodiment 5, and are not described again.

The sensor circuit comprises a power supply circuit, a control circuit and a sensing circuit, when liquid needs to be heated, the control circuit controls the selection circuit to enable the diode circuit to be connected with the heating branch circuit, so that the liquid is heated through the diode to realize the heating function;

when the liquid level of the liquid needs to be detected, the selection circuit is controlled by the control circuit, so that the diode circuit is connected with the secondary circuit, the liquid level of the liquid is detected through output signals of the power circuit, the control circuit and the sensing circuit, and the liquid level detection function is realized.

Example 7

On the basis of the above embodiments, the present application further provides an MCU liquid level sensor, as shown in fig. 8, fig. 8 is a schematic block diagram of the MCU liquid level sensor provided in embodiment 7 of the present application. The MCU liquid level sensor comprises a power supply, an MCU chip 900 and a plurality of detection circuits electrically connected with the MCU chip 900, wherein the power supply is used for providing power for the MCU chip and the detection circuits. Each detection circuit includes the power supply circuit and the sensing circuit described in any of the above embodiments, and the MCU chip 900 is detachably mounted to the ink cartridge. The detection circuits composed of the power circuit and the sensing circuit are sequentially arranged on the inner wall of the ink storage cavity of the ink box at intervals along the height extension direction of the ink box, and the detection circuits are arranged at different heights of the inner wall of the ink storage cavity. The MCU chip 900 may control the switching of the selection circuit in the power circuit to realize the switching of different functions of heating or liquid level detection, or may determine the medium environment of the detection circuit according to the voltage output by the power circuit in the detection circuit, the voltage output by the sensing circuit, and the heating information of the diode circuit, and further determine the liquid level information of the detection circuit.

Optionally, the MCU liquid level sensor may further include a calculating circuit 901, the calculating circuit 901 is electrically connected to the MCU chip 900 and the detecting circuit, respectively, the calculating circuit 901 calculates data detected by the plurality of power circuits and the sensing circuit, and the MCU chip sets the selected channel by accessing the multiplexer of the calculating circuit 901, thereby outputting a corresponding signal to an analog-to-digital conversion circuit (ADC), and thereby outputting a corresponding digital signal to the MCU chip 900.

Specifically, the MCU chip can control the heating and detection of the detection circuit based on the control signal of the printer.

Example 8

Based on the above embodiments, the present application further provides an ink cartridge, and referring to fig. 9, fig. 9 is a schematic block diagram of the ink cartridge provided in embodiment 8 of the present application. The ink cartridge includes a cartridge body provided with an ink storage chamber through which ink is stored, and the sensor circuit described in any one of embodiments 1 to 6. The detection circuits composed of the power circuit and the sensing circuit are arranged at different heights of the inner wall of the ink storage cavity, the ink is heated through the heating of the diode circuit, and the signals output by the power circuit and the sensing circuit are used for detecting the liquid level of the ink.

Specifically, the control circuit 1000, the power supply, and the multiplexer and analog-to-digital converter (ADC) in the calculation circuit 1001 are respectively disposed in the box body, and the control circuit is configured to control the power supply to provide power to different power supply circuits and sensing circuit groups, and simultaneously can control switching of a selection circuit in the power supply circuits to realize switching of different functions of heating or liquid level detection; the data tested by the power circuits and the sensing circuit are transmitted to the analog-to-digital converter through the multiplexer, the analog-to-digital converter converts the received signals into digital signals and outputs the digital signals to the control circuit, and the control circuit can control the detection circuit to work according to the digital signals.

Further, the temperature is determined according to the heating of the diode, the corresponding ratio u1 is determined according to the temperature, the ratio u2 obtained by calculating the ratio of the pressure difference delta VB and the output voltage Vref is determined, the medium environment is determined, liquid level information can be measured according to a plurality of sensor circuits, for example, the height of the ink box to be detected is h, 2 sensor circuits are designed at equal intervals, and when the 2 sensor circuits are detected to be in the ink medium, the liquid level can be judged to be more than 2/3h of the ink box to be detected; when the sensor circuit arranged below is detected to be in the ink medium and the sensor circuit arranged above is detected to be in the air medium, the liquid level can be judged to be between 1/3h and 2/3h of the ink box to be detected; when 2 sensor circuits are detected to be in the air medium, the liquid level can be judged to be below 1/3h of the ink box to be detected.

The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.