JP2019169340A - Lighting device, and light projection system - Google Patents

Abstract

To achieve a light distribution pattern with high expression in a lighting device and a light projection system for controlling a light distribution pattern by using a liquid crystal element.SOLUTION: A lighting device includes: a light source 1; an image forming part for forming an image by using the light from the light source 1; and a projection part 8 for projecting an image formed by the image forming part. The image forming part includes: a voltage control birefringence type liquid crystal element 6 having a plurality of light control regions; and a pair of polarizing plates 7a, 7b oppositely arranged by sandwiching the liquid crystal element. In the image forming part, the color tone of the light entering from one side of the polarizing plate 7a, transmitting each of the light control regions, and emitting from the other side of the polarizing plate 7b becomes at least two types of different color tones according to the size of an applied voltage in each of the plurality of light control regions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination device suitable for use as, for example, a vehicular lamp and a light projection system using the illumination device.

  Japanese Patent Laid-Open No. 2005-183327 (Patent Document 1) discloses a vehicle headlamp that blocks a light emitting unit 11 including at least one LED 11a and a part of light emitted forward from the light emitting unit. A light shielding portion 12 that forms a cut-off suitable for a light distribution pattern for use, and the light shielding portion 12 has an electro-optic element having a dimming function, and control for dimming control of the electro-optic element. 14 and the control unit is configured to change the shape of the light distribution pattern by selectively dimming the dimming part by the electrical switching control of the electro-optic element. A vehicle headlamp is disclosed. As the electro-optical element, for example, a liquid crystal element is used.

  In the vehicular lamp as described above, when it is intended to increase the power of expressing the light distribution pattern, for example, it is conceivable to make a difference in the hue of the irradiation light in each part of the light distribution pattern. In this case, each pixel as a liquid crystal element is divided into, for example, three sub-pixels, and a color filter of three primary colors is provided for each sub-pixel, and the transmitted light from each sub-pixel is mixed. Display color) can be variably set, and irradiation light having a different hue can be formed in each portion of the light distribution pattern. However, since the vehicular lamp needs to emit relatively bright light, the intensity of light incident on the liquid crystal element increases. When such strong light is incident, the color filter of each sub-pixel of the liquid crystal element absorbs heat, so that heat is also transmitted to the liquid crystal material (generally nematic liquid crystal material) in contact with the color filter. Therefore, the liquid crystal material may cause a phase transition in the isotropic phase, which may make it difficult to form a light distribution pattern with high expressive power. Such an inconvenience is not limited to the vehicular lamp, but may also occur in general lighting devices that control the light distribution pattern using a liquid crystal element or the like.

JP 2005-183327 A

  A specific aspect according to the present invention is to provide a technique capable of realizing a light distribution pattern with high expressiveness in an illumination device or the like that controls a light distribution pattern using a liquid crystal element or the like. .

[1] An illumination device according to an aspect of the present invention is formed by (a) a light source, (b) an image forming unit that forms an image using light from the light source, and (c) the image forming unit. (D) the image forming unit includes a voltage-controlled birefringent liquid crystal element having a plurality of light control regions, and a pair disposed opposite to each other with the liquid crystal element interposed therebetween. (E) the hue of the light that is incident from one of the polarizing plates in the image forming unit, passes through each of the light control regions, and is emitted from the other of the polarizing plates, The illumination device has at least two different hues according to the magnitude of the applied voltage in each of the plurality of light control regions.
[2] An optical projection system according to an aspect of the present invention includes: (a) the above-described illumination device; (b) a detection unit that detects the position of an object existing in the target space; and (c) the detection unit. A liquid crystal driving device that controls the applied voltage in each of the plurality of light control regions in the liquid crystal element of the illumination device in accordance with the detected position of the object.

  According to the above configuration, it is possible to realize a light distribution pattern with high expressiveness in an illumination device or the like that controls a light distribution pattern using a liquid crystal element or the like.

FIG. 1 is a diagram illustrating a configuration of a vehicular lamp system according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing the configuration of the liquid crystal element. FIG. 3 is a diagram illustrating an example of the relationship between the applied voltage to the liquid crystal layer of the liquid crystal element and the transmitted light spectrum. FIG. 4 is a diagram illustrating an example of the relationship between the applied voltage and the chromaticity change with respect to the liquid crystal layer of the liquid crystal element. FIG. 5 is a diagram schematically illustrating an example of an irradiation pattern formed in front of the vehicle by the vehicle lamp system. FIG. 6 is a schematic cross-sectional view showing the configuration of the liquid crystal element in the vehicle lamp system of the second embodiment. FIG. 7 is a diagram schematically illustrating an example of a light distribution pattern that can be realized using the liquid crystal element of the second embodiment. FIG. 8 is a plan view schematically showing a configuration example of each pixel region in the liquid crystal element of the second embodiment. FIG. 9 is a diagram for explaining a light source driving method. FIG. 10 is a diagram for explaining a modification of the incident light from the light source to the liquid crystal element.

  FIG. 1 is a diagram illustrating a configuration of a vehicular lamp system according to a first embodiment. The vehicle lamp system shown in FIG. 1 includes a light source 1, a condenser lens 2, a camera 3, a control device 4, a liquid crystal drive device 5, a liquid crystal element 6, a pair of polarizing plates 7a and 7b, and a projection lens 8. ing. This vehicle lamp system detects the position of a forward vehicle, a pedestrian, or the like existing around the host vehicle based on an image taken by the camera 3, and sets a certain range including the position of the forward vehicle or the like as a non-irradiation range. This is for performing selective light irradiation by setting the other range as the light irradiation range. The control device 4 corresponds to a “light source control device”. The camera 3 and the control device 4 correspond to a “detection unit”. Further, the liquid crystal element 6 and the pair of polarizing plates 7a and 7b correspond to “image forming portions”. The projection lens 8 corresponds to a “projection unit”.

  The light source 1 includes, for example, a white light LED configured by combining a yellow phosphor with a light emitting element (LED) that emits blue light. The light source 1 includes, for example, a plurality of white light LEDs arranged in a matrix or a line. In addition to the LED, the light source 1 may be a laser or a light source generally used in a vehicle lamp unit such as a light bulb or a discharge lamp. The on / off state of the light source 1 is controlled by the control device 4. The light emitted from the light source 1 enters the liquid crystal element (liquid crystal panel) 6 through the polarizing plate 7a.

  The condensing lens 2 is disposed on the front side of the light emitting portion of the light source 1, condenses the light emitted from the light source 1 and makes it incident on the liquid crystal element 6. Further, other optical systems (for example, a lens, a reflecting mirror, or a combination thereof) may exist on the path from the light source 1 to the liquid crystal element 6.

  The camera 3 captures the front of the host vehicle and outputs the image (information), and is disposed at a predetermined position in the host vehicle (for example, the upper part inside the windshield). In addition, when the camera for other uses (for example, automatic brake system etc.) is equipped with the own vehicle, you may share the camera.

  The control device 4 detects the position of a forward vehicle or a pedestrian or the like (target object) existing in the forward space by performing image processing based on an image obtained by the camera 3 that captures the forward space of the host vehicle, Set a light distribution pattern with the detected position of the vehicle ahead as the non-irradiation range and the other area as the light irradiation range, and generate a control signal to form an image corresponding to this light distribution pattern Supply to the liquid crystal driving device 5. The control device 4 controls the operation of the light source 1. The control device 4 is realized by executing a predetermined operation program in a computer system having a CPU, a ROM, a RAM, and the like, for example.

  The liquid crystal driving device 5 individually controls the alignment state of the liquid crystal layer in each pixel region of the liquid crystal element 6 by supplying a driving voltage to the liquid crystal element 6 based on a control signal supplied from the control device 4. is there.

  The liquid crystal element 6 has, for example, a plurality of pixel regions (light control regions) that can be individually controlled, and each pixel region according to the magnitude of the voltage applied to the liquid crystal layer given by the liquid crystal driving device 5. The alignment state of the liquid crystal molecules in the liquid crystal layer is variably controlled. By irradiating light from the light source 1 to the liquid crystal element 6, an image having brightness and darkness and hue corresponding to the above-described light irradiation range and non-irradiation range is formed. For example, the liquid crystal element 6 includes a vertical alignment type liquid crystal layer, and is disposed between a pair of polarizing plates 7a and 7b arranged in a crossed Nicols state, so that no voltage is applied to the liquid crystal layer (or a threshold value). In the case of the following voltage), the light transmittance is in a very low state (light shielding state). Further, the liquid crystal element 6 of the present embodiment has a relatively large retardation (Δn · d) represented by the product of the refractive index anisotropy Δn of the liquid crystal material of the liquid crystal layer and the layer thickness d (inter-substrate distance). By setting the value, the hue of the transmitted light can be changed using an electrically controlled birefringence (ECB) effect.

  The pair of polarizing plates 7 a and 7 b have, for example, their polarization axes substantially orthogonal to each other and are disposed to face each other with the liquid crystal element 6 interposed therebetween. In the present embodiment, a normally black mode is assumed, which is an operation mode in which light is shielded (voltage is extremely low) when no voltage is applied to the liquid crystal layer. As each of the polarizing plates 7a and 7b, for example, an absorption-type polarizing plate made of a general organic material (iodine type, dye type) can be used. Further, when it is desired to place more importance on heat resistance, it is also preferable to use a wire grid type polarizing plate. A wire grid type polarizing plate is a polarizing plate formed by arranging ultrafine wires made of metal such as aluminum. Further, an absorption type polarizing plate and a wire grid type polarizing plate may be used in an overlapping manner.

  The projection lens 8 spreads an image formed by light transmitted through the liquid crystal element 6 (an image having a light / dark or hue corresponding to the light irradiation range and the non-irradiation range) so as to be a light distribution for the headlights. Projecting forward, a lens designed as appropriate is used. In this embodiment, a reverse projection type projector lens is used.

  FIG. 2 is a schematic cross-sectional view showing the configuration of the liquid crystal element. The liquid crystal element 6 includes an upper substrate (first substrate) 11 and a lower substrate (second substrate) 12 that are arranged to face each other, a counter electrode (common electrode) 13 that is provided on the upper substrate 11, and a plurality that is provided on the lower substrate 12. The pixel electrode (individual electrode) 14 and a liquid crystal layer 18 disposed between the upper substrate 11 and the lower substrate 12 are included. For convenience of explanation, although not shown, alignment films for regulating the alignment state of the liquid crystal layer 18 are appropriately provided on the upper substrate 11 and the lower substrate 12, respectively.

  The upper substrate 11 and the lower substrate 12 are each a rectangular substrate in plan view, and are disposed to face each other. As each substrate, for example, a transparent substrate such as a glass substrate or a plastic substrate can be used. For example, a large number of spacers are uniformly distributed between the upper substrate 11 and the lower substrate 12, and the substrate gap is maintained at a desired size (for example, about several μm) by these spacers. As the spacer, a plastic ball that can be sprayed by a dry sprayer may be used, or a columnar body that is provided in advance on a substrate by a resin material or the like may be used.

  The counter electrode (common electrode) 13 is provided on one surface side of the upper substrate 11. The counter electrode 13 is integrally provided so as to face each pixel electrode 14 of the lower substrate 12. The counter electrode 13 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

  The plurality of pixel electrodes (individual electrodes) 14 are provided on one surface side of the lower substrate 12. These pixel electrodes 14 are configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. Each pixel electrode 14 has, for example, a rectangular outer edge shape in plan view, and is arranged in a matrix along the x direction and the y direction. A gap is provided between the pixel electrodes 14. Each of the overlapping regions of the counter electrode 13 and the pixel electrodes 14 constitutes the pixel region (light control region) described above.

  The liquid crystal layer 18 is provided between the upper substrate 11 and the lower substrate 12. In the present embodiment, the dielectric anisotropy Δε is negative, the phase transition temperature to the isotropic phase is high (for example, 130 ° C.), the chiral material is not included, and the liquid crystal is formed using a fluid nematic liquid crystal material. Layer 18 is constructed. The liquid crystal layer 18 of the present embodiment is in a uniaxial alignment state in which the alignment direction of the liquid crystal molecules is tilted in one direction when no voltage is applied, and the pretilt angle within a range of, for example, 88 ° to less than 90 ° with respect to each substrate surface. And has a substantially vertical alignment.

  As described above, the alignment films are provided on the one surface side of the upper substrate 11 and the one surface side of the lower substrate 12, respectively. As each alignment film, a vertical alignment film that restricts the alignment state of the liquid crystal layer 18 to the vertical alignment is used. Each alignment film is subjected to a uniaxial alignment process such as a rubbing process, and has a uniaxial alignment regulating force that regulates the alignment of the liquid crystal molecules of the liquid crystal layer 18 in that direction. The direction of the alignment treatment to each alignment film is set to be, for example, staggered (anti-parallel).

  The liquid crystal element 6 according to the present embodiment has several tens to several hundreds of pixel regions, which are regions defined as regions where the counter electrode 13 and the pixel electrodes 14 overlap in plan view. The regions are arranged in a matrix. In the present embodiment, the shape of each pixel region is configured to be, for example, a square shape, but the shape of each pixel region can be arbitrarily set, for example, a mixture of a rectangular shape and a square shape. Further, although the pixel regions are arranged in a matrix, they need not be arranged in a matrix. The counter electrode 13 and each pixel electrode 14 are connected to the liquid crystal driving device 5 through a wiring section (not shown), and are driven statically, for example. The applied voltage at that time is, for example, a square wave voltage of about 100 Hz to 1 kHz, and the voltage range is 0 to 50V.

  FIG. 3 is a diagram illustrating an example of the relationship between the applied voltage to the liquid crystal layer of the liquid crystal element and the transmitted light spectrum. Here, the spectral characteristics of the liquid crystal element of the example in which the cell thickness d of the liquid crystal layer 18 is 4.2 μm and the refractive index anisotropy Δn of the liquid crystal material is 0.129 are shown. In this case, the retardation of the liquid crystal layer 18 of the liquid crystal element 6 is 541.8 nm. In the liquid crystal element 6 of this embodiment, when no voltage is applied to the liquid crystal layer 18 (0 V), the transmittance is very low in the entire visible light wavelength region (approximately 400 to 700 nm) and almost no light is transmitted. . Further, the transmission spectrum changes as the applied voltage increases. Specifically, when the voltage is relatively small, the spectrum is relatively flat, but when the voltage is 5 V or more, the flatness is lost, and different spectra are obtained depending on the magnitude of the voltage. That is, the liquid crystal element of the present embodiment is a voltage-controlled birefringent liquid crystal element that can change the transmitted light to various hues depending on the magnitude of the applied voltage. In the liquid crystal element 6 of this embodiment, yellow transmitted light is obtained by applying a high voltage (for example, 50 V). When changing the color of the transmitted light, it is preferable to increase the voltage as it is without changing from the white state to the state in which no voltage is applied. Furthermore, it is preferable to change to a predetermined hue at once using overdrive driving.

  Note that the characteristics shown in FIG. 3 are examples, and different spectral characteristics can be obtained by changing the size of the retardation by increasing or decreasing the layer thickness (cell thickness) of the liquid crystal layer 18. As the retardation is increased, the type of hue of transmitted light can be increased. However, if the retardation is increased too much, the response speed to the voltage is reduced. For this reason, as retardation, it is preferable that it is 300 nm or more, Furthermore, it is preferable that it is 500 nm or more, and it is preferable that it is 1000 nm or less.

  FIG. 4 is a diagram illustrating an example of the relationship between the applied voltage and the chromaticity change with respect to the liquid crystal layer of the liquid crystal element. Specifically, FIG. 4A shows a change in chromaticity with respect to the applied voltage of the liquid crystal element of the example in which the cell thickness d of the liquid crystal layer 18 is 3.0 μm and the refractive index anisotropy Δn of the liquid crystal material is 0.129. Is shown. FIG. 4B shows the chromaticity change with respect to the applied voltage of the liquid crystal element of the example in which the cell thickness d of the liquid crystal layer 18 is 4.0 μm and the refractive index anisotropy Δn of the liquid crystal material is 0.129. . FIG. 4C shows the chromaticity change with respect to the applied voltage of the liquid crystal element of the example in which the cell thickness d of the liquid crystal layer 18 is 6.0 μm and the refractive index anisotropy Δn of the liquid crystal material is 0.129. .

  In the liquid crystal element having a cell thickness of 3.0 μm, although the change in chromaticity with respect to the voltage is small, the chromaticity changes as the voltage increases, and approaches a yellow color at a high voltage (see FIG. 4A). In the liquid crystal element having a cell thickness of 4.0 μm, the change in chromaticity with respect to voltage is larger than that in the liquid crystal element having a cell thickness of 3.0 μm (see FIG. 4B). Furthermore, in the liquid crystal element having a cell thickness of 6.0 μm, it can be seen that the chromaticity change with respect to the voltage is further increased, and the transmitted light is colored (see FIG. 4C). Specifically, the transmitted light is yellow at 5V, red at 5V, purple at 5.5V, blue at 7V, cyan at 15V, and green at 50V. The transmitted light is not so saturated as a color, but can sufficiently recognize the difference in hue with respect to white light used as normal irradiation light.

  FIG. 5 is a diagram schematically illustrating an example of an irradiation pattern formed in front of the vehicle by the vehicle lamp system. FIG. 5 schematically shows an irradiation pattern (projected image) 100 on a virtual screen several tens of meters ahead of the vehicle. In the figure, each rectangular region arranged in a matrix along the top, bottom, left, and right is an individual light distribution region in which the amount and hue of transmitted light can be individually controlled by the liquid crystal element 6. Each pixel area has a one-to-one correspondence.

  In the irradiation pattern 100, for example, the four individual light distribution regions 100a on the upper left are portions where the transmitted light is controlled to be green, and the four individual light distribution regions 100b near the center are black (non-transmitted or non-transmitted). The four individual light distribution regions 100c on the upper right side are portions where the transmitted light is controlled to be blue. In addition, each individual light distribution region other than the above in the irradiation pattern 100 is a portion where the transmitted light is controlled to be white. It should be noted that what is shown here is an example, and various light distribution patterns 100 can be obtained by variously controlling the hue of transmitted light independently in each individual light distribution region.

  FIG. 6 is a schematic cross-sectional view showing the configuration of the liquid crystal element in the vehicle lamp system of the second embodiment. In addition, the same code | symbol is used about the component which is common in the above-mentioned liquid crystal element 6 shown in FIG. 2, and detailed description is abbreviate | omitted about them. The overall configuration of the vehicular lamp system is also the same as that of the first embodiment, and detailed description thereof is omitted.

  In the liquid crystal element 6 a, an insulating film 15 is partially provided on one surface side of the upper substrate 11. Some of the plurality of counter electrodes 13 a are provided on the insulating film 15. Further, as illustrated, a wiring portion 13b for transmitting a voltage to the counter electrode 13a may be provided below the insulating film 15 as appropriate. Further, as shown in the drawing, the insulating film 15 may be appropriately provided with a through hole 16a, and the counter electrode 13a on the insulating film 15 may be connected to the wiring portion 13b below the through hole 16a. .

  Similarly, the liquid crystal element 6 a is partially provided with an insulating film 16 on one surface side of the lower substrate 12. Some of the plurality of pixel electrodes 14 a are provided on the insulating film 16. Further, as illustrated, a wiring portion 14b for transmitting a voltage to the pixel electrode 14a may be provided below the insulating film 16 as appropriate. Furthermore, although not shown, a through hole is appropriately provided in the insulating film 16, and the pixel electrode 14a on the insulating film 16 is connected to the wiring portion 14b below the through hole through the through hole. Also good.

  The insulating films 15 and 16 are obtained by appropriately patterning, for example, an organic resin film. The film thicknesses of the insulating films 15 and 16 are set as appropriate, for example, several μm. By providing these insulating films 15 and 16, the distance between the counter electrode 13a and the pixel electrode 14a, that is, the layer thickness of the liquid crystal layer 18 can be set to various different values.

  Specifically, in the region 106a, the liquid crystal layer 18 is sandwiched between each counter electrode 13a provided on the insulating film 15 and each pixel electrode 14a provided on the insulating layer 16, and the layer thickness is, for example, 3 μm. It has become. In this region 106a, chromaticity characteristics similar to those of the liquid crystal element 6 having a cell thickness of 3 μm in the above-described embodiment can be obtained (see FIG. 4A).

  Similarly, in the region 106b, the liquid crystal layer 18 is sandwiched between each counter electrode 13a provided on the insulating film 15 and each pixel electrode 14a provided on the lower substrate 12 instead of on the insulating layer 16, The layer thickness is, for example, 4.5 μm. In this region 106b, chromaticity characteristics close to those of the liquid crystal element 6 having a cell thickness of 4 μm in the above-described embodiment can be obtained (see FIG. 4B).

  Similarly, in the region 106c, the liquid crystal layer 18 is formed by the counter electrodes 13a provided on the upper substrate 11 instead of on the insulating film 15 and the pixel electrodes 14a provided on the lower substrate 12 instead of on the insulating layer 16. The layer thickness is, for example, 6 μm. In this region 106c, chromaticity characteristics similar to those of the liquid crystal element 6 having a cell thickness of 6 μm in the above-described embodiment can be obtained (see FIG. 4C).

  FIG. 7 is a diagram schematically illustrating an example of a light distribution pattern that can be realized using the liquid crystal element of the second embodiment. Similar to FIG. 5 described above, an irradiation pattern (projected image) 200 on a virtual screen several tens of meters ahead of the vehicle is schematically shown. In addition, the situation in front of the vehicle (such as a road) is also schematically shown. FIG. 8 is a plan view schematically showing a configuration example of each pixel region in the liquid crystal element of the second embodiment. In this example, a plurality of pixel regions set to various heights in the vertical direction and various widths in the horizontal direction are shown in a rectangular shape.

  A light distribution pattern 200 in FIG. 7 includes a headlamp area 201 corresponding to the center in front of the vehicle, an obstacle light distribution area 202 disposed below the headlamp area 201, the headlamp area 201, and the obstacle. Two roadside signs arranged side by side on the upper side of the two pedestrian light distribution areas 203, the headlight area 201, the obstacle light distribution area 202, and the pedestrian light distribution area 203 provided on the left and right of the light distribution area 202, respectively. The light distribution area 204 includes a guide sign light distribution area 205 disposed above the roadside sign light distribution areas 204.

  The headlamp region 201 is a region corresponding to a high beam (traveling light) and a low beam (passing light) for ensuring visibility in front of the vehicle. The headlamp area 201 is associated with the area 106a in the liquid crystal element 6a as shown in FIG. This region 106a includes a plurality of pixel regions having relatively small vertical and horizontal widths as shown in the figure, and has spectral characteristics corresponding to a cell thickness of 3 μm. The degree of change is small. For this reason, white is mainly used as irradiation light. By individually irradiating each pixel area, variable light distribution according to the position of the vehicle ahead can be realized. Further, since it has chromaticity characteristics corresponding to a cell thickness of 3 μm, only the emission color satisfying the requirements of the related laws and regulations as a lamp can be applied to the headlamp region 201.

  The obstacle light distribution area 202 is an area for forming a beam for irradiating a road surface in particular. The obstacle light distribution area 202 is also associated with the area 106a in the liquid crystal element 6a as shown in FIG. This region 106a includes a plurality of pixel regions whose vertical length and horizontal width are relatively small as shown in the figure, and has chromaticity characteristics corresponding to a cell thickness of 3 μm. The chromaticity change is small. For this reason, although white is mainly used as irradiation light, yellow irradiation light can be formed at the time of dense fog. By irradiating a region near the vertical angle of -1 °, a near field of view can be secured. Thinning irradiation can be performed by selectively using some of the plurality of pixel regions.

  The two pedestrian light distribution areas 203 are areas that form beams for irradiating pedestrians (or bicycle riders, etc.) that are present on the side of the road. The pedestrian light distribution area 203 is associated with the area 106b in the liquid crystal element 6a as shown in FIG. This region 106b includes a plurality of pixel regions having a relatively large vertical length and horizontal width as shown in the figure, and has chromaticity characteristics corresponding to a cell thickness of 4.5 μm. The change in chromaticity of light is larger than when the cell thickness is 3 μm. For this reason, for example, for a pedestrian detected by image recognition, bright white irradiation light is given to the body part, and colored (for example, yellow) irradiation light with reduced brightness is given to the face part. it can. As a result, the driver can be made aware of the presence of the pedestrian, and can also be informed of the presence of the vehicle and the vehicle state (automatic / manual driving, vehicle speed, distance, etc.).

  The two roadside sign light distribution areas 204 and the guide sign light distribution area 205 are areas that form beams for irradiating roadside signs on the side of the road and information signs on the upper side of the road. As shown in FIG. 8C, the roadside sign light distribution region 204 and the guide sign light distribution region 205 are associated with a region 106c in the liquid crystal element 6a. This region 106c includes a plurality of pixel regions whose vertical length and horizontal width are relatively larger as shown in the figure, and has chromaticity characteristics corresponding to a cell thickness of 6.0. The chromaticity change of transmitted light is large. For this reason, with respect to a roadside sign or a guide sign detected by image recognition, the hue of the irradiation light can be set variably in accordance with the position and hue, and the driver can be alerted.

  According to each embodiment as described above, irradiation light of a plurality of types of hues can be realized without using a color filter, and thus the liquid crystal can be produced without causing the above-described disadvantages when using a conventional liquid crystal element having a color filter. It is possible to realize a light distribution pattern with high expressiveness in a vehicle lamp system that controls light distribution patterns using elements.

  Note that the present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, when changing the hue of light transmitted by the liquid crystal element in each of the above-described embodiments, when the color change during switching from the first hue (for example, yellow) to the second hue (for example, blue) is not negligible As illustrated in FIG. 9, a switching period for temporarily reducing the brightness (intensity) of the emitted light from the light source 1 may be provided. In this case, since the vehicle is moving, flicker may be conspicuous when the frequency is 100 Hz or less. Therefore, the switching period is preferably 10 msec or less.

  In each of the above-described embodiments, the light emitted from the light source is made to be substantially parallel light and incident on the liquid crystal element. However, as shown in FIGS. 10A and 10B, the liquid crystal element 6 (6a) is used. If the light is incident on the center in the normal direction and the light is obliquely incident on the peripheral portion, the hue of the transmitted light at the center of the liquid crystal element and the transmitted light at the periphery can be changed.

  In the above-described embodiment, the vehicle lamp system for irradiating light ahead of the vehicle has been exemplified. However, the scope of application of the present invention is not limited to this, and the vehicle lamp system is used as a tail lamp. May be. In addition, an auto-leveling function that adjusts the optical axis direction according to the attitude of the vehicle, an AFS function that irradiates light in the traveling direction when the vehicle curves, a function that draws information on the road surface, and a vehicle state for drivers outside the vehicle Answer back function to notify, charge meter function to notify the driver outside the vehicle by the hue when the vehicle is stopped, such as an electric vehicle, etc., driving state in a vehicle equipped with an automatic driving function (during automatic driving / manual driving) It can be applied to a vehicular lamp system for various uses such as a function of notifying the outside by hue. In these cases, when it is necessary to blink the irradiation light from the state in which the vehicular lamp is turned off, a fixed voltage is applied to the liquid crystal element to fix the hue of the irradiation light, and then the light source is irradiated. It is preferable to realize a blinking state of the irradiation light by turning on and off the light. Furthermore, the present invention can be applied not only to a vehicle application but also to an illumination device and a light projection system using the illumination device in general.

1: light source
2: Condensing lens 3: Camera 4 Control device 5: Liquid crystal driving device 6: Liquid crystal element 7a, 7b: Polarizing plate 8: Projection lens 11: Upper substrate 12: Lower substrate 13: Counter electrode (common electrode)
14: Pixel electrode (individual electrode)
18: Liquid crystal layer 100: Irradiation pattern (projected image)
100a: Individual light distribution area

Claims (8)

A light source;
An image forming unit that forms an image using light from the light source;
A projection unit that projects the image formed by the image forming unit;
Including
The image forming unit includes a voltage-controlled birefringent liquid crystal element having a plurality of light control regions, and a pair of polarizing plates arranged to face each other with the liquid crystal element interposed therebetween.
In the image forming unit, the hue of the light that enters from one of the polarizing plates, passes through each of the light control regions, and exits from the other of the polarizing plates is the voltage applied to each of the plurality of light control regions. Depending on the size, there will be at least two different hues,
Lighting device. In the liquid crystal element, the retardation value represented by the product of the layer thickness of the liquid crystal layer and the refractive index anisotropy of the liquid crystal material constituting the liquid crystal layer is 300 nm or more and 1000 nm or less.
The lighting device according to claim 1. The liquid crystal element has a plurality of regions having different retardation values.
The lighting device according to claim 2. The retardation difference in each of the plurality of regions is obtained by providing a difference in the layer thickness of the liquid crystal layer in each of the plurality of regions.
The lighting device according to claim 3. The difference in layer thickness of the liquid crystal layer is at least 1 μm or more.
The lighting device according to claim 4. In each of the plurality of regions, the type of hue of the light obtained according to the magnitude of the applied voltage is different.
The lighting device according to claim 4 or 5. A light source control device for controlling the operation of the light source;
The light source control device controls the light intensity of the light source to be temporarily reduced when the hue of the light is switched from the first hue to the second hue in the image forming unit;
Lighting device. The lighting device according to any one of claims 1 to 7,
A detection unit for detecting the position of the target object existing in the target space;
A liquid crystal driving device that controls the applied voltage in each of the plurality of light control regions in the liquid crystal element of the illuminating device according to the position of the object detected by the detection unit;
Including a light projection system.