1. A vehicle lamp unit is provided with:

a light source;

a light branching element that reflects a 1 st component of light generated by the light source and transmits a 2 nd component of the light;

a light modulation element that changes a polarization direction of the 2 nd component;

an image generating element to which both the 1 st component and the 2 nd component after the polarization direction is changed are incident, the image generating element generating an image using the 1 st component and the 2 nd component; and

a lens that projects the image generated by the image generating element to a vehicle periphery,

the optical branching element and the optical modulation element are constituted as an integrated optical element,

the optical element includes:

a 1 st substrate and a 2 nd substrate arranged to face each other;

an optical film provided on one surface of the 1 st substrate opposite to the 2 nd substrate with an adhesive layer interposed therebetween, and functioning as the light branching element;

an alignment film provided on a surface of the 2 nd substrate opposite to the 1 st substrate;

a liquid crystalline medium which is provided between the optical film and the alignment film between the respective surfaces of the 1 st substrate and the 2 nd substrate, and functions as the light modulation element; and

and a sealing material provided between the respective surfaces of the 1 st substrate and the 2 nd substrate so as to surround the optical film, the alignment film, and the liquid crystalline medium, and fixed to one side of the respective surfaces of the 1 st substrate and the 2 nd substrate without interposing the optical film and the alignment film therebetween.

2. The lamp unit for a vehicle according to claim 1,

the optical film is in direct contact with the liquid crystalline medium.

3. The lamp unit for a vehicle according to claim 1 or 2, wherein,

the optical film is composed of a reflective polarizing film composed of a uniaxially stretched optical multilayer film,

in the liquid crystalline medium, liquid crystal molecules are aligned along the extension direction of the reflective polarizing film at least in the vicinity of the interface in contact with the optical film.

4. The lamp unit for a vehicle according to claim 3,

the alignment film has a uniaxial alignment regulating force,

the optical film and the alignment film are disposed so that the direction in which the reflective polarizing film is stretched and the direction in which the alignment film is uniaxially oriented are substantially orthogonal to each other.

5. The lamp unit for a vehicle according to claim 3,

the alignment film has a uniaxial alignment regulating force,

the optical film and the alignment film are disposed such that the direction of extension of the reflective polarizing film is substantially antiparallel or substantially parallel to the direction of the uniaxial orientation restriction force of the alignment film.

6. The vehicle lamp unit according to any one of claims 1 to 5,

a part or the whole of the liquid crystalline medium is polymerized.

7. The vehicle lamp unit according to any one of claims 1 to 6,

the light modulator is any one of an optically active element, an 1/2 wavelength element, and a 1/4 wavelength element.

8. A vehicle light system, comprising:

the vehicular lamp unit according to any one of claims 1 to 7; and

and a control unit for controlling the operation of the vehicle lamp unit.

Background

Japanese patent application laid-open No. 2018-185896 (patent document 1) describes a lamp unit and a vehicle lamp system using the same, the lamp unit including: a light source; a reflective polarizing plate disposed at a position where light from the light source is incident; a reflecting mirror that reflects the reflected light generated by the reflective polarizing plate and re-enters the reflective polarizing plate; a liquid crystal element disposed on the light emitting surface side of the reflective polarizing plate; a polarizing plate disposed on a light emitting surface side of the liquid crystal element; a projection lens disposed on the light emitting surface side of the polarizing plate; and a phase difference plate disposed between the reflective polarizing plate and the reflecting mirror. According to the above configuration, the light use efficiency in the vehicle lamp system that performs selective light irradiation using the liquid crystal element can be improved.

However, in the conventional vehicle lamp system, reliability such as heat resistance can be further improved by using the wire grid polarizing plate as the reflective polarizing plate, but the wire grid polarizing plate is generally expensive, which leads to an increase in cost of the entire vehicle lamp system. On the other hand, as the reflective polarizing plate, a film-like polarizing plate made of a cheaper optical multilayer film may be used. In this case, generally, higher performance can be obtained as compared with a reflection polarizing plate made of an inorganic material such as a wire grid polarizing plate, but this is disadvantageous in terms of heat resistance and moisture resistance, and it is difficult to improve reliability.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2018-185896

Disclosure of Invention

[ problems to be solved by the invention ]

An object of a specific embodiment of the present invention is to provide a lamp unit and a vehicle lamp system that have high light utilization efficiency, excellent reliability, and can achieve cost reduction.

[ means for solving the problems ]

[1] A vehicle lamp unit according to one embodiment of the present invention includes: (a) a light source; (b) a light branching element that reflects a 1 st component of light generated by the light source and transmits a 2 nd component of the light; (c) a light modulation element that changes a polarization direction of the 2 nd component; (d) an image generating element to which both the 1 st component and the 2 nd component after the polarization direction is changed are incident, the image generating element generating an image using the 1 st component and the 2 nd component; and (e) a lens that projects the image generated by the image generating element to the periphery of the vehicle, (f) an optical element in which the light branching element and the light modulation element are integrated, (g) the optical element having: (g1) a 1 st substrate and a 2 nd substrate arranged to face each other; (g2) an optical film provided on one surface of the 1 st substrate opposite to the 2 nd substrate with an adhesive layer interposed therebetween, and functioning as the light branching element; (g3) an alignment film provided on a surface of the 2 nd substrate opposite to the 1 st substrate; (g4) a liquid crystalline medium which is provided between the optical film and the alignment film between the respective surfaces of the 1 st substrate and the 2 nd substrate, and functions as the light modulation element; and (g5) a sealing material that is provided between the respective one surfaces of the 1 st substrate and the 2 nd substrate so as to surround the optical film, the alignment film, and the liquid crystalline medium, and that is fixed to one side of the respective one surfaces of the 1 st substrate and the 2 nd substrate without interposing the optical film and the alignment film therebetween.

The vehicle lamp system of the present invention is a vehicle lamp system including the vehicle lamp unit and a control unit that controls an operation of the vehicle lamp unit.

With the above configuration, it is possible to obtain a lamp unit and a vehicle lamp system that have high light use efficiency, excellent reliability, and reduced cost.

Drawings

Fig. 1 is a diagram showing a configuration of a vehicle lamp system according to an embodiment.

Fig. 2 (a) is a schematic plan view showing the structure of the optical element, and fig. 2 (B) is a schematic cross-sectional view of the optical element.

Fig. 3 is a diagram for explaining an example of a method for manufacturing an optical element.

Fig. 4 (a) and 4 (B) are views for explaining an example of the method for manufacturing the optical element.

Fig. 5 (a) and 5 (B) are views for explaining an example of the method for manufacturing the optical element.

Fig. 6 is a diagram for explaining an example of a method for manufacturing an optical element.

Fig. 7 (a) and 7 (B) are views for explaining an example of the method for manufacturing the optical element.

Fig. 8 (a), 8 (B), and 8 (C) are diagrams for explaining an example of a method for manufacturing an optical element.

Fig. 9 is a diagram showing a configuration of a vehicle lamp system according to a modification.

Description of the reference symbols

1: light source, 2: concave reflector, 3: optical element, 4: reflector, 5: liquid crystal element, 6a, 6b: polarizing plate, 7: projection lens, 8: control unit, 9: camera, 11: upper substrate (1 st substrate), 12: lower substrate (2 nd substrate), 13: optical film, 14: adhesive layer, 15: alignment film, 16: liquid crystal medium, 17: sealing material, 18: sealing material, 19: injection port

Detailed Description

Fig. 1 is a diagram showing a configuration of a vehicle lamp system according to an embodiment. The illustrated vehicle lamp system is used, for example, to form illumination light based on a predetermined light distribution pattern for illuminating the front of a vehicle, and includes a light source 1, a concave reflector (1 st reflector) 2, an optical element 3, a reflector (2 nd reflector) 4, a liquid crystal element 5, a pair of polarizing plates 6a and 6b, a projection lens 7, a control unit 8, and a camera 9. This vehicle lamp system can use all of the 2 polarized lights separated by the optical element 3 for the formation of the irradiation light, and therefore the light utilization efficiency is high. The "vehicle lamp unit" is configured to include a light source 1, a concave reflector (1 st reflector) 2, an optical element 3, a reflector (2 nd reflector) 4, a liquid crystal element 5, a pair of polarizing plates 6a and 6b, and a projection lens 7.

The light source 1 includes, for example, an LED (light emitting diode) that emits white light and a driving circuit thereof. The number of the LED chips included in the light source 1 may be 1 or more. When a plurality of LEDs are arranged, it is preferable that the LEDs are arranged in one or more rows in a direction (depth direction) perpendicular to the paper surface of fig. 1. For example, in the present embodiment, the light source 1 having a 2-column structure in which 4 LEDs are arranged in the depth direction for each column is used.

The concave reflector 2 reflects the light generated by the light source 1, condenses it, and enters the optical element 3. Further, instead of the concave reflector 2, a lens may be disposed to condense light from the light source 1.

The optical element 3 has a function as a polarization beam splitter (light branching element) for separating light generated by the light source 1 and incident via the concave reflector 2 into 2 polarized lights, reflecting one polarized light (1 st component) and transmitting the other polarized light (2 nd component), and a function as a light modulation element for rotating the polarization direction of the transmitted one polarized light by 90 °. The polarized light reflected by the optical element 3 enters the liquid crystal element 5.

The reflector 4 reflects the polarized light transmitted through the optical element 3, condenses it, and enters the liquid crystal element 5. Further, instead of the reflector 4, a lens may be disposed to condense the light from the light source 1.

The liquid crystal element 5 is disposed so as to be sandwiched between the pair of polarizing plates 6a and 6b, and forms a desired image by transmitting or blocking incident light individually for each pixel region. In this embodiment, the liquid crystal element 5 has a driver IC mounted on a substrate thereof. As the liquid crystal element 5, for example, a liquid crystal element having a liquid crystal layer of a vertical alignment mode of uniaxial alignment can be used. In the present embodiment, the liquid crystal element 5 and the pair of polarizing plates 6a and 6b correspond to an "image generating element".

The pair of polarizing plates 6a and 6b are, for example, polarizing plates (iodine-based or dye-based) using a general organic material, and are arranged such that their respective polarization axes (absorption axis or transmission axis) are substantially orthogonal to each other, for example. As the polarizing plates 6a and 6b, polarizing plates having other structures (e.g., wire grid type polarizing plates and optical multilayer film type polarizing plates) may be used.

The projection lens 7 is an inverted projection type projection lens having a focal point at a specific distance, and projects an image generated by the liquid crystal element 5 and the pair of polarizing plates 6a and 6b toward the periphery of the vehicle (the front of the vehicle in the present embodiment). The projection lens 7 sets N/a (numerical aperture) according to the angle of incident light. When the angle of light incident most obliquely with respect to the center line of the projection lens 7 is defined as θ, N/a is sin θ.

The control unit 8 performs image processing using the image of the vehicle periphery captured by the camera 9 to detect an object such as a vehicle ahead, thereby setting a light distribution pattern for dimming or blocking a region where the vehicle ahead is present, and for irradiating light to other regions, for example. Then, the control unit 8 generates a control signal for forming an image for realizing the light distribution pattern on the liquid crystal element 5 and supplies the control signal to the liquid crystal element 5.

Fig. 2 (a) is a schematic plan view showing the structure of the optical element. Fig. 2 (B) is a schematic cross-sectional view of the optical element. The sectional view of fig. 2 (B) corresponds to the section at the line a-a shown in fig. 2 (a).

The optical element 3 includes an upper substrate (1 st substrate) 11, a lower substrate (2 nd substrate) 12, an optical film 13, an adhesive layer 14, an alignment film 15, a liquid crystalline medium (liquid crystal layer) 16, a sealing material 17, and a sealing material 18.

The upper substrate 11 and the lower substrate 12 are each a light-transmitting substrate such as a glass substrate, and are disposed to face each other.

The optical film 13 is a reflective polarizing film composed of an optical multilayer film. As shown in fig. 2 (B), the optical film 13 separates the light L incident from the light source 1 into 2 polarized lights L1, L2. The light L1 with one polarization is transmitted through the optical film 13, and the light L2 with the other polarization is reflected by the optical film 13. That is, the optical film 13 functions as a polarizing beam splitter. As the optical film 13, for example, a reflective polarizing film (uniaxially stretched multilayer laminated film) composed of a uniaxially stretched optical multilayer film disclosed in international publication No. 2012/173170 can be used.

The adhesive layer 14 is used to fix the optical film 13 made of a reflective polarizing film to the upper substrate 11, and is interposed between the upper substrate 11 and the optical film 13. The adhesive layer 14 is made of a material having light transmittance.

The alignment film 15 is used to impart a uniaxial alignment regulating force to the liquid crystal molecules of the liquid crystalline medium 16. In the present embodiment, a horizontally oriented film subjected to uniaxial orientation treatment is used as the orientation film 15.

The liquid crystalline medium 16 is made of a liquid crystal material having fluidity and is disposed between the upper substrate 11 and the lower substrate 12. Specifically, the liquid crystalline medium 16 is provided between the optical film 13 of the upper substrate 11 and the alignment film 15 of the lower substrate 12, and is in direct contact with the optical film 13. The liquid crystalline medium 16 of the present embodiment is configured to have TN (twisted nematic) orientation that satisfies the morgan condition and has optical rotation. With such a configuration, the polarization direction of the polarized light L1 can be rotated by 90 ° by making the orientation direction of the incident side substantially orthogonal or substantially parallel to the polarization direction of the incident polarized light L1. The liquid crystalline medium 16 may be configured to function as a λ/2 plate (1/2 wavelength element as an optical modulator) by setting a phase difference determined by a layer thickness thereof and a refractive index anisotropy Δ n of a liquid crystal material to a predetermined value for uniform (Homogeneous) alignment, for example.

The sealing material 17 is provided to seal the liquid crystalline medium 16 and fix the upper substrate 11 and the lower substrate 12 so as to surround the liquid crystalline medium 16 along the outer edges of the upper substrate 11 and the lower substrate 12. Fig. 2 (a) shows a pattern to facilitate understanding of the range in which the sealing material 17 is formed. In the present embodiment, the sealing material 17 is provided so as to be in direct contact with each of the upper substrate 11 and the lower substrate 12 without interposing the optical film 13, the adhesive layer 14, and the alignment film 15 therebetween.

The sealing material 18 is used to seal an opening 19 provided in the sealing material 17 for use when the liquid crystal material is injected.

Since the optical element 3 of the present embodiment has a structure in which the optical film 13 is surrounded by the upper substrate 11, the lower substrate 12, the liquid crystalline medium 16, and the sealing material 17, the optical film 13 is less susceptible to external humidity. Therefore, even when a relatively inexpensive reflective polarizing film is used, reliability (moisture resistance) can be improved. Further, since the liquid crystal medium 16 functioning as a light modulation element is also integrally formed, the number of components can be reduced. Further, since the optical element 3 can be manufactured in the same configuration as the manufacturing process of a conventional general liquid crystal element, mass productivity is good, and manufacturing cost can be reduced. An example of the method for manufacturing the optical element 3 will be described in detail below with reference to fig. 3 to 8.

As shown in fig. 3, a plurality of optical films 13 are bonded to one surface (inner surface) of the large substrate 111 with an adhesive layer 14 interposed therebetween. The large substrate 111 is divided into a plurality of upper substrates 11 in a subsequent step. Each optical film 13 is an optical film having an adhesive layer 14 applied to the back surface thereof in advance, and is bonded to the large substrate 111 by cutting the optical film into a predetermined size. In addition, bubbles after the optical film 13 is attached are removed by performing a high pressure (Autoclave) process. As shown in the drawing, alignment marks 120 made of an ITO film, a metal film, or the like may be provided at four corners of the large substrate 111.

Further, an alkali blocking film (alkali blocking film) such as a silicon oxide film is preferably provided on the other surface (outer surface) of the large substrate 111. On the other surface of the large substrate 111, a plurality of layers of a silicon oxide film having a low refractive index or a metal oxide film having a high refractive index (for example, a tantalum oxide film) are preferably provided as the antireflection film and the alkali barrier film. Further, an alkali barrier film such as a silicon oxide film may be provided on one surface of the large substrate 111.

Fig. 4 (a) is an enlarged view of a part of the large substrate 111 shown in fig. 3. As shown in fig. 4 a, the optical film 13 is subjected to rubbing treatment (alignment treatment). In the present embodiment, the rubbing direction 121 is, for example, a direction toward the right in the drawing. In this case, when an optical film that is uniaxially stretched is used as the optical film 13, the stretching direction 122 is preferably substantially parallel to the rubbing direction 121. This generates a uniaxial orientation regulating force in the extending direction in the optical film 13.

Fig. 4 (B) is an enlarged view of a part of the large substrate 112 to be cut into a plurality of lower substrates 12 in a subsequent step. As shown in the drawing, alignment marks 130 made of an ITO film, a metal film, or the like may be provided on the large substrate 112. As shown in fig. 4B, a plurality of alignment films 15 are formed on one surface (inner surface) of the large substrate 112. Specifically, for example, a horizontally oriented film material made of polyimide is applied by a method such as flexographic printing, and then fired at a temperature of about 180 to 250 ℃. Then, each alignment film 15 is subjected to rubbing treatment (alignment treatment). In the present embodiment, the rubbing direction 131 is, for example, a direction toward a lower side in the figure. This generates a uniaxial alignment regulating force along the rubbing direction 131 in each alignment film 15.

Next, as shown in fig. 5 (a), the gap material 20 is scattered on one surface of the large substrate 111. The spacer 20 is used to maintain a predetermined gap between the upper substrate 11 and the lower substrate 12, and is, for example, a spherical member having a particle diameter of approximately 1.5 to 50 μm. In the present embodiment, the gap material 20 having a particle diameter of 18 μm is used. In this case, when the liquid crystal medium 16 is TN-aligned, the particle size of the gap material 20 is set so as to satisfy the morgan condition. In the case where the liquid crystalline medium 16 is uniformly aligned, the particle size of the gap material 20 is set so that the retardation of the liquid crystalline medium 16 becomes 225nm in accordance with the relationship with Δ n of the liquid crystal material in order to function as a λ/2 plate at a light wavelength of 550 nm.

The larger the particle diameter of the gap material 20 (i.e., the thickness of the liquid crystalline medium 16), the higher the performance as a λ/2 plate tends to be, while the particle diameter of the gap material 20 of 50 μm or more may affect the optical performance due to scattering or the like. Therefore, the particle diameter of the gap material 20 is preferably set to be less than 50 μm.

As shown in fig. 5 (B), a plurality of sealing materials 17 are formed on one surface of the large substrate 112 so as to surround the alignment films 15. As the sealing material 17, for example, an acrylate resin of a type that is cured by ultraviolet rays and heat can be used. The sealing material 17 can be formed by, for example, screen printing, dispenser printing, or the like. Further, a gap control material may be added to the sealing material 17. Specifically, it is preferable to add a gap control material having a particle size obtained by adding the film thickness of the optical film 13 and the particle size of the gap material 20 dispersed in the large substrate 111. For example, if the film thickness of the optical film 13 is 60 μm, a gap control material having a particle size of about 80 μm may be added. The sealing material 17 is preferably provided so as not to overlap with the optical film 13 and the like.

Next, as shown in fig. 6, the large substrate 111 and the large substrate 112 are stacked so that their respective surfaces (inner surfaces) face each other. At this time, in order to orient the liquid crystalline medium 16 in TN, the large substrate 111 and the large substrate 112 are opposed to each other so that the rubbing direction 121 and the rubbing direction 131 are substantially orthogonal to each other. In order to uniformly align the liquid crystalline medium 16, the rubbing directions of the large substrate 111 and the large substrate 112 are set in advance such that the rubbing direction 121 is substantially parallel to the rubbing direction 131. Fig. 6 shows a case where the large substrate 111 and the large substrate 112 are stacked on each other when viewed from the other surface side of the large substrate 112. Alignment adjustment of the large substrate 111 and the large substrate 112 can be performed using the alignment marks 120 and 130. At this time, the ultraviolet curable resin 140 provided in a dot shape in advance is irradiated with ultraviolet rays, whereby the positional relationship between the large substrate 111 and the large substrate 112 can be fixed.

After that, the large substrate 111 and the large substrate 112 are entirely pressed with a transparent flat plate (quartz, glass, or the like), and then irradiated with ultraviolet rays, thereby curing the respective sealing materials 17 and firmly adhering to the large substrates 111 and 112. The large substrates 111 and 112 may be vacuum-packed with a transparent film, and irradiated with ultraviolet rays in this state.

In addition, although the width of each sealing material 17 may be slightly increased by curing each sealing material 17, in this case, it is also preferable to set the forming conditions of each sealing material 17 so that each sealing material 17 does not overlap each optical film 13. Further, it is preferable that the formation conditions of the respective sealing materials 17 are set so that the optical films 13 do not go outside the formation range of the sealing materials 17 even if the respective sealing materials 17 partially overlap the respective optical films 13.

Next, as shown in fig. 7 a, a plurality of scribe lines 141 and 142 are provided on the other surface (outer surface) of each of the large substrates 111 and 112. These scribe lines 141, 142 are provided so as to be able to divide the large substrates 111, 112 into respective regions which will eventually become the optical elements 3, respectively. The scribe lines 141 and 142 can be formed by, for example, a scribing machine using a diamond wheel.

Next, as shown in fig. 7 (B), the large substrates 111 and 112 are divided along the scribe lines 142 in the vertical direction in the drawing to form the elongated cells 113. Thereby, each injection port 19 is exposed. Such division (breaking) can be performed using, for example, a breaker.

Next, as shown in fig. 8 (a), the injection tank 150 of the injection machine is filled with the liquid crystal material 151, and the injection ports 19 of the cells 113 are aligned with the injection tank 150. Then, the chamber of the implanter is evacuated (at a low pressure) to thereby defoam the liquid crystal material 151. Thereafter, as shown in fig. 8 (B), the liquid crystal material 151 is filled into the region surrounded by the respective sealing materials 17 of the cell 113 by bringing the respective injection ports 19 of the cell 113 into contact with the liquid crystal material 151 in a vacuum state and returning the inside of the chamber to atmospheric pressure.

Next, each injection port 19 of the cell 113 is sealed with the sealing material 18, and the cell 113 is divided along the scribe line 141, thereby obtaining the optical element 3 shown in fig. 8 (C). Specifically, the blocking material 18 is applied to each injection port 19, and after the blocking material 18 is placed in the cell 113 to some extent, the blocking material 18 is cured by ultraviolet irradiation. Further, cleaning, chamfering, and the like of the optical element 3 may be performed as necessary.

The optical element 3 of the present embodiment is not inferior in the function as a polarizing plate in the normal direction of the substrate surface to the case where the optical film 13 is used alone. Further, the function as a polarizing plate (light-shielding property in the cross nicol case) is also high in the direction forming an angle with the normal direction of the substrate surface. This is because the angle of light incident on the substrate changes according to snell's law. For example, the light-shielding properties at cross nicols are approximately the same in the following two cases: in the 1 st case, 2 optical films 13 are used as a single body, and light is made incident at an angle of 30 ° to the substrate surface normal direction, and in the 2 nd case, 2 optical elements 3 are used, and light is made incident at an angle of 19 ° to the substrate surface normal direction. From this, it is understood that the optical element 3 has high performance as a polarizing plate.

In addition, since the optical film 13 is protected by the upper substrate 11, the lower substrate 12, the liquid crystalline medium 16, and the sealing material 17, the optical element 3 of the present embodiment is also higher in reliability than the case where the optical film 13 is used alone. For example, when the optical film 13 is subjected to a reliability test at high temperature and high humidity (85 ℃, 85%) as a single body, deterioration of the function as a polarizing plate (reduction in light-shielding rate, reflection unevenness) is observed in a test time of about 24 hours. In contrast, the optical element 3 of the present embodiment is not deteriorated for a test time of 4000 hours or more, although it depends on the production conditions. As another comparative example, in the case of performing a reliability test in a structure in which the optical film 13 is sandwiched only by glass substrates without being surrounded by a sealing material, deterioration was observed for about 1500 hours.

In addition, the optical element 3 of the present embodiment is also advantageous in terms of manufacturing cost. Specifically, since the manufacturing method of collectively manufacturing the substrates from the large substrate and finally dividing the substrates can be adopted as exemplified above, the manufacturing cost of one manufacturing can be suppressed. On the other hand, for example, a wire grid polarizing plate using an inorganic material or a broadband wavelength plate using an inorganic material has a disadvantage that the cost is rapidly increased if the required area is increased because it is difficult to obtain a wire grid polarizing plate or a broadband wavelength plate having a large area and uniform performance although the reliability is high, and the cost is also high.

In the optical element 3 of the present embodiment, the liquid crystalline medium 16 functioning as a λ/2 plate and the optical film 13 functioning as a polarizing beam splitter are integrated by being in direct contact with each other between the upper substrate 11 and the lower substrate 12, and therefore reflection loss due to surface reflection or the like can be suppressed. Further, since an optical film of an organic material system can be used as the optical film 13, higher performance can be obtained as compared with a polarization beam splitter made of an inorganic material.

With the configuration of the above embodiment, a vehicle lamp system having high light utilization efficiency and excellent reliability can be obtained.

The present invention is not limited to the above-described embodiments. For example, a liquid crystalline medium formed by polymerization (polymer stabilization) may be used as the liquid crystalline medium 16 in the optical element 3 of the above embodiment. In this case, a liquid crystal monomer having a photopolymerizable group may be injected as a liquid crystal material (see fig. 8B), and then irradiated with light such as ultraviolet light to cure the liquid crystal material. In this case, for example, light irradiation can be performed simultaneously with the formation of the sealing material 19 (see fig. 8C). By polymerizing a part or all of the liquid crystalline medium 16, heat resistance and long-term reliability can be further improved.

The configuration of the vehicle lamp system is not limited to the above embodiment, and various modifications are possible. Fig. 9 is a diagram showing a configuration of a vehicle lamp system according to a modification. The vehicle lamp system shown in fig. 9 includes a light source 201, a collimator lens 202, an optical element 203, a reflector 204, a liquid crystal element 205, a polarizing plate 206, a projection lens 207, a control unit 208, and a camera 209. Note that, the same names are used for the same functions as those of the above-described embodiment, and detailed description thereof is omitted.

In the vehicle lamp system of the modification shown in fig. 9, light generated by the light source 201 is condensed by the collimator lens 202, converted into substantially parallel light, and made incident on the optical element 203. The optical element 203 has the same structure as the optical element 3 of the above embodiment (see fig. 2), and the lower substrate 12 is disposed so as to face the light source 201. The liquid crystalline medium 16 is uniformly aligned, and Δ n · d, which is the product of Δ n and the layer thickness of the liquid crystal material, is set to be approximately 135 nm. Thereby, the liquid crystalline medium 16 functions as a λ/4 plate (1/4 wavelength element as a retardation element). The orientation direction of the liquid crystalline medium 16 is set to be 45 ° away from the transmission axis or the reflection axis of the optical film 13. In addition, Δ n · d may be set so that λ/4 of the liquid crystalline medium 16 is functionally equivalent to λ/4 of a 3 λ/4 plate, a 5 λ/4 plate, or the like. For example, if Δ n · d is set to approximately 410nm, a function as a 3 λ/4 plate can be obtained.

With such an arrangement, light incident on the optical element 203 passes through the liquid crystal medium 16 and is separated into 2 polarized lights in the optical film 13. The separated one polarized light passes through the liquid crystal medium 16 as reflected light and becomes circularly polarized light, and is reflected by the reflection plate 204 and passes through the liquid crystal medium 16 again, thereby becoming polarized light rotated by 90 ° from the polarization direction of the separated one polarized light. If this polarized light is incident again on the optical film 13, it can pass through the optical film 13, and as a result, most of the light component passes through the optical element 203.

With the configuration of the modification, a vehicle lamp system having high light utilization efficiency and excellent reliability can be obtained.