JP7499588B2 - Lamp unit, vehicle lighting system - Google Patents

Description

The present invention relates to a lamp unit and a vehicle lighting system for emitting light to the surroundings of a vehicle (e.g., the front).

JP 2019-204711 A (Patent Document 1) describes a vehicle lighting system in which light emitted from a light source such as an LED and incident at a wide angle is separated into two polarized lights by a polarization separation element, one of the polarized lights is made incident on a liquid crystal element, and the transmitted light is irradiated to the periphery of the vehicle (for example, the front) by a projection lens. In this vehicle lighting system, for example, an image corresponding to a light distribution pattern in which a dimming range is set according to the position of a vehicle ahead photographed by a camera is generated by a liquid crystal element, thereby selectively irradiating light to the front of the vehicle. Since the polarization separation element is used in a vehicle, taking into consideration heat resistance, etc., a wire grid type polarizing plate having periodically arranged thin metal wires or a multilayer film polarization separation element having a multilayer film in which thin films made of two materials with different refractive indices are alternately stacked is preferably used.

Generally, wire grid polarizers and multilayer polarizing separators tend to have poor polarization separation characteristics for light incident at wide angles, which can result in so-called light leakage. For this reason, in a vehicle lighting system configured as described above, the contrast of the light distribution pattern decreases due to light leakage through the multilayer polarizing separator or the like.

JP 2019-204711 A

One of the objectives of a specific embodiment of the present invention is to improve the contrast of the light distribution pattern in vehicle lighting systems that use liquid crystal elements.

[ 1] A lamp unit according to one aspect of the present invention comprises:
A lamp unit for use in a vehicle lighting system,
A light source;
A light collecting member that collects light generated by the light source;
a liquid crystal element disposed in correspondence with a focal position of the light condensed by the condensing member;
a first incident-side polarizing plate disposed on a light incident side of the liquid crystal element;
a second incident side polarizing plate disposed between the first incident side polarizing plate and the liquid crystal element;
a third input polarizer disposed between the second input polarizer and the liquid crystal element;
a first exit side polarizing plate disposed on the light exit side of the liquid crystal element;
Including,
the first incident-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, which transmits polarized light along the transmission axis and reflects polarized light along the reflection axis,
the second incident-side polarizing plate is an absorptive polarizing plate that absorbs a light component along an absorption axis,
the third incident-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, which transmits polarized light along the transmission axis and reflects polarized light along the reflection axis;
This is a lamp unit.
[ 2] A vehicle lighting system according to one aspect of the present invention is a vehicle lighting system including the lamp unit described above and a control unit that controls the lamp unit.

The above configuration makes it possible to improve the contrast of the light distribution pattern in lamp units and vehicle lighting systems that use liquid crystal elements.

Fig. 1A is a schematic diagram for explaining a measurement system for transmittance characteristics, and Fig. 1B is a graph showing an example of the measurement results of transmittance. Fig. 2(A) is a diagram for explaining the positional relationship of each optical axis when a liquid crystal element and a viewing angle compensation plate are arranged between a pair of multilayer film polarization separation elements or a pair of dye-based absorption type polarizers. Fig. 2(B) is a graph showing an example of a measurement result of transmittance when each element, etc. is arranged as shown in Fig. 2(A) and used as a measurement object and measured with the measurement system shown in Fig. 1(A). FIG. 3 is a diagram showing a configuration of a vehicle lighting system according to the first embodiment. FIG. 4 is a diagram for explaining the positional relationship of the optical axes of the optical elements in the lamp unit of the vehicle lighting system of the first embodiment. FIG. 5 is a diagram showing a configuration of a lamp unit in a vehicle lighting system according to the second embodiment. FIG. 6 is a diagram showing a configuration of a lamp unit in a vehicle lighting system according to the third embodiment.

First, the characteristics of the multilayer film polarization separation element and the dye-based absorption polarizing plate are explained. Figure 1 (A) is a schematic diagram for explaining the measurement system for transmittance characteristics. Using the measurement system shown in the figure, the polar angle dependence of the transmittance is obtained when the absorption axes of a pair of multilayer film polarization separation elements and a pair of dye-based absorption polarizing plates are arranged orthogonally (crossed Nicol arrangement). Note that the "multilayer film polarization separation element" is a polarization separation element having a multilayer film in which thin films made of two substances with different refractive indexes are alternately stacked as described above. Also, the "dye-based absorption polarizing plate" is a polarizing plate manufactured by adsorbing and orienting a dichroic dye on a resin film such as a polyvinyl alcohol-based film, and determines the polarization direction by absorbing polarized light (light component) with a polarization direction along the absorption axis.

As shown in FIG. 1A, a measurement object 100 consisting of, for example, a pair of multilayer film polarization separation elements or a pair of dye-based absorptive polarizing plates is prepared, and arranged so that the absorption axes of each are aligned in the 0°-180° and 90°-270° azimuths. Then, a light source 101 is arranged on the back side of the measurement object 100, and a light receiver 102 is arranged on the front side. Approximately parallel light is irradiated from the light source 101 toward the light receiver 102. A polar angle θ is set, which is the inclination angle of the light source 101 and the light receiver 102 based on the normal direction to the front and back surfaces of the measurement object 100, and an azimuth angle φ is set counterclockwise based on the 0° azimuth. Then, the azimuth angle φ is fixed, and the polar angle θ is changed to measure the transmittance of the measurement object 100.

Figure 1 (B) is a graph showing an example of the measurement result of the transmittance. In Figure 1 (B), the horizontal axis indicates the polar angle θ, and the vertical axis indicates the transmittance (the same applies to Figure 2 (B) described later). The example of the measurement result shown in the figure was measured by fixing the azimuth angle φ at 45° and changing the polar angle θ in the range of ±60° using a pair of commonly available multilayer film polarization separation elements and a pair of dye-based absorption type polarizers. As shown in the figure, in the pair of multilayer film polarization separation elements, the transmittance increases significantly as the absolute value of the polar angle θ increases. On the other hand, in the pair of dye-based absorption type polarizers, there is the same tendency that the transmittance increases as the absolute value of the polar angle θ increases, but the transmittance value itself is small. Compared to the pair of multilayer film polarization separation elements described above, the transmittance is more than twice as high at polar angles of ±20° or more, and the difference is particularly noticeable. From these characteristics, it can be seen that by using a dye-based absorption type polarizer, light leakage can be suppressed even for light incident at a wide angle.

Figure 2(A) is a diagram for explaining the positional relationship of each optical axis when a liquid crystal element and a viewing angle compensation plate are arranged between a pair of multilayer film polarization separation elements or a pair of dye-based absorption type polarizers. Also, Figure 2(B) is a graph showing an example of a measurement result of the transmittance when each element, etc. is arranged as shown in Figure 2(A) as the measurement object and measured with the measurement system shown in Figure 1(A). The measurement object shown in Figure 2(A) includes, in order from the light source 101 side (rear side), a light source side polarizer (rear side polarizer) 201, a viewing angle compensation plate 202, a liquid crystal element 203, and a projection side polarizer (front side polarizer) 204. A multilayer film polarization separation element or a dye-based absorption type polarizer is used as the light source side polarizer 201 and the projection side polarizer 204.

The light source side polarizing plate 201 is arranged so that its absorption axis a1 is oriented at 45° upward to the right in the figure. The projection side polarizing plate 204 is arranged so that its absorption axis a4 is oriented at 45° upward to the left in the figure. In other words, the light source side polarizing plate 201 and the projection side polarizing plate 204 are arranged so that their absorption axes a1 and a4 are approximately perpendicular to each other (crossed Nicol arrangement). The viewing angle compensation plate 202 is a negative biaxial optically anisotropic retardation plate, and is arranged between the light source side polarizing plate 201 and the liquid crystal element 203 so that its in-plane slow axis a2 is oriented at 45° upward to the left in the figure. The liquid crystal element 203 has, for example, a vertical alignment type liquid crystal layer that has been subjected to uniaxial alignment processing, and is oriented downward in the figure so that the alignment direction a3 (when viewed in a plan view) of the liquid crystal molecules at approximately the center of the liquid crystal layer when a voltage is applied is approximately 45° to both the absorption axes a1 and a4 of the light source side polarizer 201 and the projection side polarizer 204.

The measurement results shown in FIG. 2B are examples of the results of measuring the transmittance characteristics using a pair of commonly available multilayer film polarization separation elements and a pair of dye-based absorption polarizing plates. Here, the azimuth angle φ was set to be approximately 45° with respect to either the absorption axis a1 of the light source side polarizing plate 201 or the absorption axis a4 of the projection side polarizing plate 204, and the polar angle θ was set to be variable within the range of ±60°. In addition, as a comparative example, measurements were also taken when the viewing angle compensation plate 202 was omitted. As shown in the figure, in both the case where a pair of multilayer film polarization separation elements is used as the light source side polarizing plate 201 and the projection side polarizing plate 204, and the case where a pair of dye-based absorption polarizing plates is used as the light source side polarizing plate 201 and the projection side polarizing plate 204, the transmittance tends to be lower when the viewing angle compensation plate 202 is used than when it is not used, and light leakage is suppressed even when the polar angle θ is large. However, the transmittance is significantly lower when using a dye-based absorption polarizer than when using a multilayer polarization separation element, and the difference is particularly significant at more than twice the normal range at polar angles of ±20° or more. In other words, it can be seen that light leakage is significantly suppressed even when the polar angle θ is large.

In the above studies, a comparison was made between a multilayer film polarization separation element, which is a type of transmissive reflective polarizer, and a dye-based absorptive polarizer, which is a type of absorptive polarizer. However, similar results were obtained when a wire-grid polarizer, which is a type of transmissive reflective polarizer, was used instead of the multilayer film polarization separation element, or when a dye-based absorptive polarizer, which is a type of absorptive polarizer, was used instead of the dye-based absorptive polarizer.

Based on the above findings, it can be said that absorption-type polarizers such as dye-based absorption-type polarizers and dye-absorption-type polarizers are superior in terms of transmittance characteristics (suppression of light leakage). On the other hand, as mentioned above, from the viewpoint of use in vehicles, it can be said that transmission-reflection-type polarizers made of inorganic materials such as multilayer film polarization separation elements and wire grid polarizers are superior in terms of reliability such as heat resistance. Therefore, the inventors of the present application came up with the idea that it is possible to utilize the advantages of both by combining dye-based absorption-type polarizers and multilayer film polarization separation elements while taking into consideration the arrangement order, etc. Below, an embodiment of a lamp unit and a vehicle lighting system based on this idea will be described in detail.

First Embodiment
3 is a diagram showing the configuration of a vehicle lamp system according to the first embodiment. The vehicle lamp system shown in the figure includes a light source 1, a reflector 2, a polarizing beam splitter 3, a reflector 4, a λ/2 retardation plate 5, a first incident side polarizing plate 6a, a second incident side polarizing plate 6b, a first exit side polarizing plate 6c, a viewing angle compensation plate 7, a liquid crystal element 8, a projection lens 9, a control unit 10, and a camera 11. In this embodiment, a lamp unit 50 is configured including the light source 1, the reflector 2, the polarizing beam splitter 3, the reflector 4, the λ/2 retardation plate 5, the first incident side polarizing plate 6a, the second incident side polarizing plate 6b, the first exit side polarizing plate 6c, the viewing angle compensation plate 7, the liquid crystal element 8, and the projection lens 9. In this embodiment, the reflectors 2 and 4 and the polarizing beam splitter 3 correspond to the "light collecting member".

The light source 1 is configured to include a white light LED that is configured by combining a light emitting element (LED) that emits blue light with a yellow phosphor. The light source 1 includes, for example, a plurality of white light LEDs arranged in a matrix or line. In this embodiment, the light source 1 is arranged so that the light it emits is incident on the reflector 2.

The reflector 2 reflects the light emitted from the light source 1 in the direction of the polarizing beam splitter 3.

The polarizing beam splitter 3 transmits light polarized in a specific direction among the incident light, and reflects light polarized in other directions. For example, a multilayer film polarization separation element or a wire grid polarizer can be used as the polarizing beam splitter 3.

The reflector 4 reflects the polarized light that passes through the polarizing beam splitter 3 in the direction of the liquid crystal element 8, focusing the light at a predetermined focal position.

From the viewpoint of light utilization efficiency, it is preferable that the reflectors 2, 4 and the polarizing beam splitter 3 are configured to cause light to be incident at a wide angle relative to the first incident side polarizing plate 6a, for example, a range of ±20° or more with the normal direction of the first incident side polarizing plate 6a being 0°.

The λ/2 retardation plate 5 rotates the polarization direction of the polarized light reflected by the reflector 4 by 90° and outputs it.

The first incident polarizing plate 6a is made of the above-mentioned transmissive reflective polarizing plate (multilayer film polarization separation element or wire grid polarizing plate) and is disposed on the light incident side of the liquid crystal element 8 at a position where the polarized light reflected by the polarizing beam splitter 3 or reflector 4 is incident.

The second incident side polarizer 6b is made of the above-mentioned absorption type polarizer (a dye-based absorption type polarizer or a dye absorption type polarizer) and is disposed between the first incident side polarizer 6a and the liquid crystal element 8.

The first exit polarizer 6b is made of the transmissive reflective polarizer (multilayer film polarized light separation element or wire grid polarizer) described above, and is disposed at a position where the polarized light that has passed through the liquid crystal element 8 is incident, i.e., on the light exit side of the liquid crystal element 8.

The viewing angle compensation plate 7 is, for example, a negative biaxial optically anisotropic retardation plate, and is disposed between the second incident side polarizing plate 6b and the liquid crystal element 8.

The liquid crystal element 8 has, for example, a number of pixel regions (light control regions) that can be controlled individually, and the orientation state of the liquid crystal molecules in the liquid crystal layer of each pixel region is variably controlled according to the control signal of the control unit 10. As a result, an image is formed having brightness and hue corresponding to the light irradiation range and the dimming range. As the liquid crystal element 8 of this embodiment, for example, one that has been subjected to uniaxial orientation processing and in which the liquid crystal molecules of the liquid crystal layer are oriented approximately vertically when no voltage is applied is used. The liquid crystal element 8 is arranged corresponding to the focal position of the light focused by the polarizing beam splitter 3 and the reflector 4.

The projection lens 9 expands the image (an image having brightness or hue corresponding to the light irradiation range and dimming range) formed by the first entrance polarizer 6a, the second entrance polarizer 6b, the liquid crystal element 8, and the first exit polarizer 6c to form a headlight light distribution and projects it forward of the vehicle. For example, an inverted projection type projector lens is used. The numerical aperture NA of the projection lens 9 can be expressed as NA = sin θ, where θ is the angle between the central axis and the light incident most obliquely with respect to the central axis of the projection lens 9.

The control unit 10 detects the positions of vehicles ahead, pedestrians, etc. (objects) in the space ahead by performing image processing based on images obtained by the camera 11 that captures the space ahead of the vehicle, sets a light distribution pattern in which the positions of the detected vehicles ahead, etc. are designated as dimming ranges (non-illuminated ranges) and the remaining areas are designated as light illumination ranges, generates control signals for forming an image corresponding to this light distribution pattern, and supplies the control signals to the liquid crystal element 8.

Figure 4 is a diagram for explaining the positional relationship of the optical axes of each optical element in the lamp unit of the vehicle lighting system of the first embodiment. The lamp unit 50 is arranged in the following order from the side where the light generated by the light source 1 is incident: a first incident side polarizing plate 6a, a second incident side polarizing plate 6b, a viewing angle compensation plate 7, a liquid crystal element 8, and a first exit side polarizing plate 6c.

The first incident side polarizing plate 6a has a transmission axis and an absorption axis (reflection axis) that are approximately orthogonal to each other, and is arranged so that the absorption axis A1 of the two is oriented at 45° upward to the right in the figure. The second incident side polarizing plate 6b is arranged so that the absorption axis A2 of the two is oriented at 45° upward to the right in the figure. That is, the first incident side polarizing plate 6a and the second incident side polarizing plate 6b are arranged so that the absorption axes A1 and A2 of the two are approximately parallel to each other. The first exit side polarizing plate 6c has a transmission axis and an absorption axis (reflection axis) that are approximately orthogonal to each other, and is arranged so that the absorption axis A5 of the two is oriented at 45° upward to the left in the figure. That is, the first incident side polarizing plate 6a, the second incident side polarizing plate 6b, and the first exit side polarizing plate 6c are arranged so that the absorption axes A1 and A2 of the two are approximately orthogonal to the absorption axis A5 (crossed Nicol arrangement).

In this specification, "substantially parallel" does not necessarily mean strictly parallel in the geometric sense, but means that the directions of the two axes are aligned within a range that reflects manufacturing errors, etc. (for example, within a range of 0°±5°), and "substantially perpendicular" does not necessarily mean strictly perpendicular in the geometric sense, but means that the directions of the two axes intersect within a range that reflects manufacturing errors, etc. (for example, within a range of 90°±5°).

The viewing angle compensation plate 7 is disposed between the second entrance polarizer 6b and the liquid crystal element 8 so that its in-plane slow axis A3 is oriented at 45° upward to the left in the figure. The liquid crystal element 8 has a vertical alignment type liquid crystal layer that has been subjected to uniaxial alignment processing as described above, and is disposed in a downward orientation in the figure so that the alignment direction A4 (when viewed in a plane) of the liquid crystal molecules at approximately the center of the liquid crystal layer when a voltage is applied is approximately 45° to each of the absorption axes A1, A2, and A5 of the first entrance polarizer 6a, the second entrance polarizer 6b, and the first exit polarizer 6c.

In the lamp unit 50 and vehicle lighting system of the first embodiment having the above-mentioned configuration, light other than the light having vibrations parallel to the transmission axis of the first incident side polarizing plate 6a is reflected back to the light source 1 side (the side of the reflector 2 and reflector 4), and light having vibrations parallel to the transmission axis and incident at a wide angle is transmitted and incident on the second incident side polarizing plate 6b. Since the first incident side polarizing plate 6a and the second incident side polarizing plate 6b are arranged with their respective absorption axes A1 and A2 approximately parallel to each other, the light absorption in the second incident side polarizing plate 6b is slight. In other words, compared to the case where light is directly incident on the second incident side polarizing plate 6b without passing through the first incident side polarizing plate 6a, the amount of light incident on the second incident side polarizing plate 6b is suppressed, so that damage to the second incident side polarizing plate 6b due to heat can be prevented. Furthermore, because an absorptive polarizing plate is used as the second incident-side polarizing plate 6b, it is possible to further suppress light leakage for light incident at a wide angle as described above, thereby improving the contrast in the light distribution pattern of the light irradiated forward of the vehicle.

Second Embodiment
Fig. 5 is a diagram showing the configuration of a lamp unit in a vehicle lighting system of the second embodiment. The overall configuration of the vehicle lighting system is the same as that of the first embodiment, so a description thereof will be omitted here (see Fig. 3). The lamp unit 50a of the second embodiment shown in Fig. 5 basically has a common configuration with the lamp unit 50 of the first embodiment, and differs in that a second exit side polarizing plate 6d is added. In Fig. 5, the common configurations are given the same reference numerals, and a description thereof will be omitted.

In the lamp unit 50a of the second embodiment, the second exit side polarizer 6d is disposed between the first exit side polarizer 6c and the liquid crystal element 8. This second exit side polarizer 6d is made of an absorption type polarizer (a dye-based absorption type polarizer or a dye absorption type polarizer) like the second entrance side polarizer 6b, and its absorption axis A6 is disposed approximately parallel to the absorption axis A5 of the first exit side polarizer 6c.

By providing the second exit side polarizing plate 6d in this way, the following effects are further added compared to the first embodiment. Specifically, the first exit side polarizing plate 6c reflects light other than the light having vibrations parallel to the transmission axis toward the liquid crystal element 8, and the light incident at a wide angle is not reflected, but the amount of light is suppressed compared to when the light is directly incident on the second exit side polarizing plate 6d. Therefore, the light absorption by the second exit side polarizing plate 6d is slight, and damage due to heat can be avoided. In addition, since the second exit side polarizing plate 6d has the effect of suppressing light leakage for light incident at a wide angle, light leakage from the first exit side polarizing plate 6c is suppressed when the liquid crystal element 8 is driven to correspond to the dark state. This makes it possible to further improve the contrast in the light distribution pattern of the light irradiated forward of the vehicle.

Third Embodiment
Fig. 6 is a diagram showing the configuration of a lamp unit in a vehicle lighting system of the third embodiment. The overall configuration of the vehicle lighting system is the same as that of the first embodiment, so a description thereof will be omitted here (see Fig. 3). The lamp unit 50b of the third embodiment shown in Fig. 6 basically has a common configuration with the lamp unit 50a of the second embodiment, and differs in that a third entrance side polarizing plate 6e and a third exit side polarizing plate 6f are added. In Fig. 6, the common configurations are given the same reference numerals, and a description thereof will be omitted.

In the lamp unit 50b of the third embodiment, the third incident side polarizer 6e is disposed between the second incident side polarizer 6b and the viewing angle compensation plate 7. This third incident side polarizer 6e is made of a transmissive reflective polarizer (multilayer film polarization separation element or wire grid polarizer) like the first incident side polarizer 6a, and has a transmission axis and an absorption axis (reflection axis) that are approximately perpendicular to each other, of which the absorption axis A7 is disposed approximately parallel to the absorption axes A1 and A2 of the first incident side polarizer 6a and the second incident side polarizer 6b. In addition, the third exit side polarizer 6f is disposed between the second exit side polarizer 6d and the liquid crystal element 8. Like the first exit side polarizer 6c, the third exit side polarizer 6f is made of a transmissive reflective polarizer (a multilayer film polarization separation element or a wire grid polarizer) and has a transmission axis and an absorption axis (reflection axis) that are approximately perpendicular to each other, with the absorption axis A8 being arranged approximately parallel to the absorption axes A5 and A6 of the first exit side polarizer 6c and the second exit side polarizer 6d.

In this way, by configuring a pair of transmissive reflective polarizers (multilayer film polarization separation element or wire grid polarizer) on each of the incident side and the exit side and arranging an absorption polarizer (dye-based absorption polarizer or dye absorption polarizer) between them, the effect of suppressing damage caused by heat to the light source 1, the second incident side polarizer 6b, the second exit side polarizer 6d, etc. can be further obtained compared to the second embodiment. Specifically, even if external light is incident from the first exit side polarizer 6c side, the first component (first polarized light), which is half of the external light, is reflected by the first exit side polarizer 6c. In addition, the remaining half, the second component (second polarized light), is transmitted, but when the liquid crystal element 8 is driven to correspond to the dark state, the second component of light is also reflected by the third incident side polarizer 6e, so it does not reach the light source 1 side. This makes it possible to avoid damage caused by heat to the light source 1, which is the focal position, and also to suppress damage or deterioration caused by heat to the second entrance side polarizing plate 6b and the second exit side polarizing plate 6d, which are made of an absorption type polarizing plate, such as a dye-based absorption type polarizing plate or a dye absorption type polarizing plate.

The present invention is not limited to the contents of the above-mentioned embodiments, and can be implemented in various modifications within the scope of the gist of the present invention. For example, the arrangement of the optical axes of each polarizing plate is not limited to the above-mentioned contents. For example, by arranging the absorption axis of the second incident side polarizing plate 6b not parallel to the absorption axis of the first incident side polarizing plate 6a (or the third incident side polarizing plate 6e) (for example, by arranging them to be shifted by several degrees), the color tone of the emitted light can be changed to a color tone different from that of the light emitted from the light source 1. The same is true for the second exit side polarizing plate 6d, the first exit side polarizing plate 6c, and the third exit side polarizing plate 6f. In addition, when a dye-absorbing polarizing plate is used, the color tone of the emitted light can also be changed to a color tone different from that of the light emitted from the light source 1 by using a dye-absorbing polarizing plate having a color tone that is not neutral, such as a color tone of violet or blue. According to these, the color tone in the light distribution pattern of the light irradiated in front of the vehicle can be variably set.

In addition, in each of the above-mentioned embodiments, a lamp unit 50 or the like is assumed in which the light generated by the light source 1 passes through each of the reflectors 2, 4, the polarizing beam splitter 3, and the λ/2 retardation plate 5 and enters the liquid crystal element 8 from the first entrance side polarizing plate 6a side, but the optical path from the light source 1 to the liquid crystal element 8 is not limited to this. For example, the light generated and emitted by the light source 1 and collected by a lens or the like may be directly entered into the liquid crystal element 8 from the first entrance side polarizing plate 6a side.

In addition, in each of the above-described embodiments, a vehicle lighting system that irradiates light in a desired light distribution pattern in front of the vehicle has been described as an example, but the target area for irradiating light is not limited to the front of the vehicle, and can be any area around the vehicle.

1: Light source, 2: Reflector, 3: Polarizing beam splitter, 4: Reflector, 5: λ/2 retardation plate, 6a: First entrance polarizer, 6b: Second entrance polarizer, 6c: First exit polarizer, 6d: Second exit polarizer, 6e: Third entrance polarizer, 6f: Third exit polarizer, 7: Viewing angle compensation plate, 8: Liquid crystal element, 9: Projection lens, 10: Control unit, 11: Camera, 50, 50a, 50b: Lamp unit

Claims (12)

A lamp unit for use in a vehicle lighting system,
A light source;
A light collecting member that collects light generated by the light source;
a liquid crystal element disposed in correspondence with a focal position of the light condensed by the condensing member;
a first incident-side polarizing plate disposed on a light incident side of the liquid crystal element;
a second incident side polarizing plate disposed between the first incident side polarizing plate and the liquid crystal element;
a third input polarizer disposed between the second input polarizer and the liquid crystal element;
a first exit side polarizing plate disposed on the light exit side of the liquid crystal element;
Including,
the first incident-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, and transmitting polarized light along the transmission axis and reflecting polarized light along the reflection axis;
the second incident-side polarizing plate is an absorptive polarizing plate that absorbs a light component along an absorption axis,
the third incident-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, which transmits polarized light along the transmission axis and reflects polarized light along the reflection axis;
Lamp unit. the first exit-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, which transmits polarized light along the transmission axis and reflects polarized light along the reflection axis;
2. The lamp unit according to claim 1. the absorption axis of the second incident-side polarizing plate and the reflection axis of the first incident-side polarizing plate are substantially parallel to each other;
3. A lamp unit according to claim 1 or 2. the reflection axis of the third incident-side polarizing plate and the absorption axis of the second incident-side polarizing plate are substantially parallel to each other;
2. The lamp unit according to claim 1. a second exit side polarizing plate disposed between the first exit side polarizing plate and the liquid crystal element;
The second exit side polarizing plate is an absorptive polarizing plate that absorbs light components along an absorption axis.
The lamp unit according to any one of claims 1 to 4. the absorption axis of the second exit-side polarizing plate and the reflection axis of the first exit-side polarizing plate are substantially parallel to each other;
6. The lamp unit according to claim 5. a third exit side polarizing plate disposed between the second exit side polarizing plate and the liquid crystal element;
the third output-side polarizing plate has a transmission axis and a reflection axis, and is a transmission-reflection type polarizing plate that transmits polarized light along the transmission axis and reflects polarized light along the reflection axis;
7. A lamp unit according to claim 5 or 6. the reflection axis of the third exit-side polarizing plate and the absorption axis of the second exit-side polarizing plate are substantially parallel to each other;
8. The lamp unit according to claim 7 . A lamp unit for use in a vehicle lighting system,
A light source;
A light collecting member that collects light generated by the light source;
a liquid crystal element disposed in correspondence with a focal position of the light condensed by the condensing member;
a first incident-side polarizing plate disposed on a light incident side of the liquid crystal element;
a second incident side polarizing plate disposed between the first incident side polarizing plate and the liquid crystal element;
a first exit side polarizing plate disposed on the light exit side of the liquid crystal element;
Including,
the first incident-side polarizing plate is a transflective polarizing plate having a transmission axis and a reflection axis, and transmitting polarized light along the transmission axis and reflecting polarized light along the reflection axis;
the second incident-side polarizing plate is an absorptive polarizing plate that absorbs a light component along an absorption axis,
an alignment direction of liquid crystal molecules at approximately the center of the liquid crystal layer when a voltage is applied to the liquid crystal element is approximately 45° with respect to a reflection axis of the first incident side polarizer and an absorption axis of the second incident side polarizer;
Lamp unit. Further comprising a viewing angle compensation plate disposed between the second incident side polarizing plate and the liquid crystal element.
10. The lamp unit according to claim 9. the reflection axis of the first incident-side polarizing plate and the absorption axis of the second incident-side polarizing plate are substantially parallel to each other,
a slow axis of the visual angle compensation plate is substantially perpendicular to the absorption axis of the first incident side polarizing plate and the absorption axis of the second incident side polarizing plate;
11. The lamp unit according to claim 10. A vehicle lighting system comprising: a lamp unit according to any one of claims 1 to 11; and a control unit that controls the lamp unit.

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