JP7053331B2 - Lighting equipment, light projection system - Google Patents

Description

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

Japanese Patent Application Laid-Open No. 2005-183327 (Patent Document 1) describes a vehicle headlight by blocking a light emitting unit 11 composed of at least one LED 11a and a part of light emitted from the light emitting unit toward the front. The light-shielding unit 12 includes a light-shielding unit 12 that forms a cutoff suitable for a light distribution pattern for light distribution, and the light-shielding unit 12 controls an electro-optical element having a dimming function and dimming control of the electro-optical element. It is composed of a unit 14 and a unit, and is configured to change the shape of the light distribution pattern by selectively dimming the dimming portion by the electrical switching control of the electro-optical element by this control unit. Vehicle headlights are disclosed. As the electro-optical element, for example, a liquid crystal element is used.

When trying to enhance the expressive power of the light distribution pattern in the above-mentioned vehicle lighting equipment, for example, it is conceivable to make the hue of the irradiation light different in each part of the light distribution pattern. In this case, each pixel is divided into, for example, three sub-pixels as a liquid crystal element, and a color filter of the three primary colors is provided for each sub-pixel to mix the transmitted light from each sub-pixel to obtain the hue for each pixel. The display color) can be set variably, and irradiation light having different hues can be formed in each part of the light distribution pattern. However, since it is necessary to irradiate a relatively bright light in a vehicle lamp, the intensity of the light incident on the liquid crystal element is increased. When such high-intensity light is incident, the color filter of each sub-pixel of the liquid crystal element absorbs heat, so that heat is also transferred to the liquid crystal material (generally nematic liquid crystal material) in contact with the color filter. Therefore, the liquid crystal material may undergo a phase transition in an isotropic phase, making it difficult to form a highly expressive light distribution pattern. It should be noted that such inconvenience may occur not only in vehicle lighting equipment but also in general lighting devices that control a light distribution pattern by using a liquid crystal element or the like.

Japanese Unexamined Patent Publication No. 2005-183327.

One of the specific aspects of the present invention is to provide a technique capable of realizing a highly expressive light distribution pattern in a lighting device or the like that controls a light distribution pattern using a liquid crystal element or the like. ..

[1] The lighting device of one aspect according to the present invention is a lighting device for irradiating the front of a vehicle with light, using (a) a light source that emits light and (b) light from the light source. It includes an image forming portion that forms an image and (c) a projection portion that projects the image formed by the image forming portion, and (d) the image forming portion is a voltage having a plurality of optical control regions. It has a control double refraction type liquid crystal element and a pair of polarizing plates arranged opposite to each other with the liquid crystal element interposed therebetween. The hue of the light transmitted through each of the above and emitted from the other of the polarizing plate has a plurality of types of different hues depending on the magnitude of the applied voltage in each of the plurality of optical control regions. f) The light source control device temporarily reduces the intensity of light emitted from the light source when the hue of the light is switched from the first hue to the second hue in the image forming unit. It is a lighting device that controls the operation of .
[2] The light projection system of one aspect according to the present invention is composed of (a) the above-mentioned lighting device, (b) a detection unit that detects the position of an object existing in the target space, and (c) the detection unit. It is a light projection system including a liquid crystal drive device that controls the applied voltage in each of the plurality of light control regions in the liquid crystal element of the lighting device according to the position of the object to be detected.

According to the above configuration, it is possible to realize a highly expressive light distribution pattern in a lighting device or the like that controls a light distribution pattern by using a liquid crystal element or the like.

FIG. 1 is a diagram showing a configuration of a vehicle lighting system according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing the configuration of the liquid crystal element. FIG. 3 is a diagram showing 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 showing an example of the relationship between the voltage applied to the liquid crystal layer of the liquid crystal element and the change in chromaticity. FIG. 5 is a diagram schematically showing an example of an irradiation pattern formed in front of a vehicle by a vehicle lighting system. FIG. 6 is a schematic cross-sectional view showing the configuration of a liquid crystal element in the vehicle lighting system of the second embodiment. FIG. 7 is a diagram schematically showing an example of a light distribution pattern that can be realized by 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 method of driving a light source. 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 showing a configuration of a vehicle lighting system according to the first embodiment. The vehicle lighting 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 lighting system detects the positions of vehicles in front, pedestrians, etc. that exist around the own vehicle based on the image taken by the camera 3, and sets a certain range including the positions of the vehicles in front to the non-irradiation range. The purpose is to set and set the other range to the light irradiation range to perform selective light irradiation. The control device 4 corresponds to the "light source control device". Further, the camera 3 and the control device 4 correspond to the "detection unit". Further, the liquid crystal element 6 and the pair of polarizing plates 7a and 7b correspond to the "image forming portion". Further, the projection lens 8 corresponds to the "projection unit".

The light source 1 is configured to include, for example, a white light LED 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 a line. As the light source 1, in addition to the LED, a laser, and further, a light source generally used for a vehicle lamp unit such as a light bulb or a discharge lamp can be used. The on / off state of the light source 1 is controlled by the control device 4. The light emitted from the light source 1 is incident on the liquid crystal element (liquid crystal panel) 6 via the polarizing plate 7a.

The condensing lens 2 is arranged on the front side of the light emitting portion of the light source 1, and condenses the light emitted from the light source 1 and causes the light emitted from the light source 1 to be incident on the liquid crystal element 6. Further, another optical system (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 own vehicle and outputs the image (information) thereof, and is arranged at a predetermined position (for example, the upper part inside the windshield) in the own vehicle. If the vehicle is equipped with a camera for other purposes (for example, an automatic braking system), the camera may be shared.

The control device 4 detects the position of a front vehicle, a pedestrian, or the like (object) existing in the front space by performing image processing based on an image obtained by the camera 3 that captures the front space of the own vehicle. A light distribution pattern is set with the detected position of the vehicle in front as the non-irradiation range and the other area as the light irradiation range, and a control signal for forming an image corresponding to this light distribution pattern is generated. It is supplied to the liquid crystal drive device 5. Further, 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, for example, a CPU, a ROM, a RAM, and the like.

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

The liquid crystal element 6 has, for example, a plurality of pixel regions (optical control regions) that can be individually controlled, and each pixel region corresponds to the magnitude of the voltage applied to the liquid crystal layer given by the liquid crystal drive device 5. The orientation state of the liquid crystal molecules in the liquid crystal layer is variably controlled. By irradiating the liquid crystal element 6 with the light from the light source 1, an image having light and darkness and hue corresponding to the above-mentioned light irradiation range and non-irradiation range is formed. For example, the liquid crystal element 6 includes a vertically oriented liquid crystal layer, is arranged between a pair of polarizing plates 7a and 7b arranged at orthogonal Nicols, and no voltage is applied (or a threshold value) to the liquid crystal layer. When the voltage is as follows), the light transmittance is extremely low (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 (distance between substrates). By setting it to a value, the hue of transmitted light can be changed by using an electric field controlled birefringence effect (ECB).

For example, the pair of polarizing plates 7a and 7b have their polarization axes substantially orthogonal to each other, and are arranged so as to face each other with the liquid crystal element 6 interposed therebetween. In the present embodiment, a normally black mode, which is an operation mode in which light is shielded (transmittance becomes extremely low) when no voltage is applied to the liquid crystal layer, is assumed. As the polarizing plates 7a and 7b, for example, an absorption type polarizing plate made of a general organic material (iodine-based or dye-based) 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. The wire grid type polarizing plate is a polarizing plate formed by arranging ultrafine wires made of a metal such as aluminum. Further, the absorption type polarizing plate and the wire grid type polarizing plate may be used in combination with each other.

The projection lens 8 expands the image formed by the light transmitted through the liquid crystal element 6 (an image having light and darkness or hue corresponding to the light irradiation range and the non-irradiation range) so as to be the light distribution for the headlights of the own vehicle. It projects forward, and an appropriately designed lens 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. A plurality of liquid crystal elements 6 are provided on the upper substrate (first substrate) 11 and the lower substrate (second substrate) 12 arranged to face each other, the counter electrode (common electrode) 13 provided on the upper substrate 11, and the lower substrate 12. The pixel electrode (individual electrode) 14 and the liquid crystal layer 18 arranged between the upper substrate 11 and the lower substrate 12 are included. Although not shown for convenience of explanation, an alignment film for regulating the alignment state of the liquid crystal layer 18 is appropriately provided on the upper substrate 11 and the lower substrate 12, respectively.

The upper substrate 11 and the lower substrate 12 are rectangular substrates in a plan view, and are arranged so as 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 spacers keep the substrate gap at a desired size (for example, about several μm). As the spacer, a plastic ball that can be sprayed by a dry sprayer may be used, or a columnar body previously provided on the 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).

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). Each pixel electrode 14 has, for example, a rectangular outer edge shape in a plan view, and is arranged in a matrix along the x-direction and the y-direction. A gap is provided between each pixel electrode 14. Each of the overlapping regions of the counter electrode 13 and each pixel electrode 14 constitutes the pixel region (optical 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, a liquid crystal display using a nematic liquid crystal material having a negative dielectric constant anisotropy Δε, a high phase transition temperature to an isotropic phase (for example, 130 ° C.), no chiral material, and fluidity. Layer 18 is configured. The liquid crystal layer 18 of the present embodiment is in a uniaxially oriented state in which the orientation direction of the liquid crystal molecules is inclined in one direction when no voltage is applied, and the pretilt angle is in the range of, for example, 88 ° or more and less than 90 ° with respect to each substrate surface. It is set to have a substantially vertical orientation.

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

The liquid crystal element 6 of the present embodiment has tens to hundreds of pixel regions, which are regions in which the counter electrode 13 and each pixel electrode 14 are defined as each of the overlapping regions in a plan view, and these pixels. The regions are arranged in a matrix. In the present embodiment, the shape of each pixel region is configured to be square, for example, but the shape of each pixel region can be arbitrarily set, such as a mixture of rectangular and square shapes. Further, although the pixel areas are arranged in a matrix, they do not have to be arranged in a matrix. The facing electrode 13 and each pixel electrode 14 are connected to the liquid crystal drive device 5 via a wiring portion (not shown), and are statically driven, for example. As the applied voltage at that time, for example, a square wave voltage of about 100 Hz to 1 kHz is used, and the voltage range is 0 to 50 V.

FIG. 3 is a diagram showing 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 the voltage to the liquid crystal layer 18 is not applied (0 V), the transmittance is extremely low in the entire visible light wavelength range (generally 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 can be obtained depending on the magnitude of the voltage. That is, the liquid crystal element of the present embodiment is a voltage-controlled birefringence type liquid crystal element capable of changing 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 raise the voltage as it is without temporarily changing the voltage from the white state to the non-voltage state. Further, it is preferable to use overdrive drive to change the hue to a predetermined hue at once.

The characteristics shown in FIG. 3 are an example, 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. The larger the retardation, the more types of hue the transmitted light can have, but if it is too large, the response speed to voltage will be slow. Therefore, the retardation is preferably 300 nm or more, more preferably 500 nm or more, and preferably 1000 nm or less.

FIG. 4 is a diagram showing an example of the relationship between the voltage applied to the liquid crystal layer of the liquid crystal element and the change in chromaticity. Specifically, FIG. 4A shows a change in chromaticity with respect to an applied voltage of the liquid crystal element of the embodiment 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 a change in chromaticity with respect to an applied voltage of the liquid crystal element of the embodiment 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 a change in chromaticity with respect to an applied voltage of the liquid crystal element of the embodiment 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 a liquid crystal element having a cell thickness of 3.0 μm, the change in chromaticity with respect to voltage is small, but the chromaticity changes with increasing voltage, and it approaches yellow at high voltage (see FIG. 4A). A liquid crystal element having a cell thickness of 4.0 μm has a larger change in chromaticity with respect to voltage than a liquid crystal element having a cell thickness of 3.0 μm (see FIG. 4B). Further, it can be seen that in the liquid crystal element having a cell thickness of 6.0 μm, the chromaticity change with respect to the voltage becomes larger and the transmitted light is colored (see FIG. 4C). Specifically, transmitted light of yellow at a voltage of 4 V, red at 5 V, purple at 5.5 V, blue at 7 V, cyan at 15 V, and green at 50 V is obtained. The transmitted light is not so saturated as a color, but the difference in hue can be sufficiently recognized with respect to the white light used as a normal irradiation light.

FIG. 5 is a diagram schematically showing an example of an irradiation pattern formed in front of a vehicle by a vehicle lighting 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, and in this example, the liquid crystal element 6 There is a one-to-one correspondence with each pixel area.

In this irradiation pattern 100, for example, the four individual light distribution regions 100a on the upper left side are the 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). It is a portion controlled to dark color), and the four individual light distribution regions 100c on the upper right side are portions where the transmitted light is controlled to blue. Further, 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 the example shown here is an example, and it is possible to obtain various light distribution patterns 100 by independently controlling the hue of transmitted light in each individual light distribution region.

FIG. 6 is a schematic cross-sectional view showing the configuration of a liquid crystal element in the vehicle lighting system of the second embodiment. The same reference numerals are used for the components common to the liquid crystal element 6 shown in FIG. 2, and detailed description thereof will be omitted. Further, the overall configuration of the vehicle lighting system is also the same as that of the first embodiment, and detailed description thereof will be omitted.

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

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

The above-mentioned insulating films 15 and 16 can be obtained by appropriately patterning, for example, an organic resin film or the like, respectively. The film thickness of each of the insulating films 15 and 16 is appropriately set, and is, for example, several μm. By providing these insulating films 15 and 16, the mutual 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 thereof 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 the counter electrodes 13a provided on the insulating film 15 and the pixel electrodes 14a provided not on the insulating layer 16 but on the lower substrate 12. The layer thickness is, for example, 4.5 μm. In this region 106b, chromaticity characteristics similar 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 the insulating film 15 and the pixel electrodes 14a provided on the lower substrate 12 instead of the insulating layer 16. It is sandwiched and its 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 showing an example of a light distribution pattern that can be realized by using the liquid crystal element of the second embodiment. Similar to FIG. 5 described above, the irradiation pattern (projected image) 200 on the virtual screen at a distance of several tens of meters in front of the vehicle is schematically shown. In addition, the state in front of the vehicle (road, etc.) is also schematically shown. Further, 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.

The light distribution pattern 200 of FIG. 7 has a headlight region 201 corresponding to the center in front of the vehicle, an obstacle light distribution region 202 arranged below the headlight region 201, a headlight region 201, and an obstacle. Two roadside signs arranged side by side above 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 sides of the light distribution area 202, respectively. The light distribution area 204 and the guide sign light distribution area 205 arranged above the roadside sign light distribution area 204 are included.

The headlight area 201 is an area corresponding to a high beam (running light) and a low beam (passing light) for ensuring visibility in front of the vehicle. As shown in FIG. 8A, the headlight region 201 is associated with the region 106a in the liquid crystal element 6a. As shown in the figure, this region 106a includes a plurality of pixel regions having a relatively small vertical length and horizontal width, and has spectral characteristics corresponding to a cell thickness of 3 μm, so that the color of transmitted light is obtained. The degree change is small. Therefore, white is mainly used as the irradiation light. By individually irradiating and controlling each pixel area, variable light distribution can be realized according to the position of the vehicle in front. Further, since it has a chromaticity characteristic corresponding to a cell thickness of 3 μm, it is possible to irradiate the headlight region 201 with only the emission color that satisfies the requirements of the relevant regulations as a lamp body.

The obstacle light distribution region 202 is a region that forms a beam for irradiating the road surface in particular. As shown in FIG. 8A, the obstacle light distribution region 202 is also associated with the region 106a in the liquid crystal element 6a. As shown in the figure, this region 106a includes a plurality of pixel regions having a relatively small vertical length and horizontal width, and has chromaticity characteristics corresponding to a cell thickness of 3 μm, so that light is emitted. The change in chromaticity is small. For this reason, white is mainly used as the irradiation light, but yellow irradiation light can be formed in a dense fog or the like. A short-distance field of view can be secured by irradiating an area near a vertical angle of -1 °. Thinning irradiation can also be performed by selectively using some of the plurality of pixel regions.

The two pedestrian light distribution regions 203 are regions that form a beam for irradiating a pedestrian (or a cyclist or the like) existing on the side of the road in particular. As shown in FIG. 8B, the pedestrian light distribution region 203 is associated with the region 106b in the liquid crystal element 6a. As shown in the figure, this region 106b includes a plurality of pixel regions having a relatively large vertical length and horizontal width, and has chromaticity characteristics corresponding to a cell thickness of 4.5 μm, and thus is transparent. The change in chromaticity of light is larger than that in the case of a cell thickness of 3 μm. Therefore, for example, to a pedestrian detected by image recognition, a bright white irradiation light may be given to the body part, and a colored (for example, yellow) irradiation light with reduced brightness may be given to the face part. can. This makes it possible to make the driver aware of the existence of a pedestrian, and also to inform the pedestrian of the existence of the vehicle and the state of the vehicle (automatic driving / manual driving, vehicle speed, distance, etc.).

The two roadside sign light distribution areas 204 and the guide sign light distribution area 205 are regions that form a beam for irradiating a roadside sign existing on the side of the road or a guide sign existing on the upper side of the road. As shown in FIG. 8C, the roadside sign light distribution area 204 and the guide sign light distribution area 205 are associated with the area 106c in the liquid crystal element 6a. As shown in the figure, this region 106c includes a plurality of pixel regions having a relatively larger vertical length and horizontal width, and has chromaticity characteristics corresponding to a cell thickness of 6.0 μm . Therefore, the change in chromaticity of transmitted light is large. Therefore, it is possible to variably set the hue of the irradiation light according to the position and hue of the roadside sign and the guide sign detected by the image recognition, and alert the driver.

According to each of the above embodiments, since it is possible to realize irradiation light of a plurality of types of hues without using a color filter, the liquid crystal display does not cause the above-mentioned inconvenience when a conventional liquid crystal element having a color filter is used. It is possible to realize a highly expressive light distribution pattern in a vehicle lighting system that controls a light distribution pattern using an element.

The present invention is not limited to the contents of the above-described embodiment, and can be variously modified and carried out within the scope of the gist of the present invention. For example, when the hue of the transmitted light by the liquid crystal element is changed in each of the above-described embodiments, the color change during switching from the first hue (for example, yellow) to the second hue (for example, blue) cannot be ignored. As illustrated in FIG. 9, a switching period may be provided to temporarily reduce the brightness (intensity) of the emitted light of the light source 1. In this case, since the vehicle moves, flicker may be noticeable when the frequency is 100 Hz or less, so the switching period is preferably 10 msec or less.

Further, in each of the above-described embodiments, the light emitted from the light source is made substantially parallel and incident on the liquid crystal element, but as shown in FIGS. 10 (A) and 10 (B), the liquid crystal element 6 (6a). If light is incident on the center of the liquid crystal element from the normal direction and light is incident on the peripheral portion from an angle, the hues of the transmitted light in the center of the liquid crystal element and the transmitted light in the periphery can be changed.

Further, in the above-described embodiment, the vehicle lighting system for irradiating the front of the vehicle with light has been exemplified, but the scope of application of the present invention is not limited to this, and it is a vehicle lighting system used as a tail light. You may. In addition, an auto-leveling function that adjusts the direction of the optical axis according to the posture of the vehicle, an AFS function that irradiates light in the direction of travel when the vehicle is curved, a function that draws information on the road surface, and a function that displays the vehicle status to the driver outside the vehicle. An answerback function to notify, a charge meter function to notify the driver outside the vehicle of the amount of charge by hue when the vehicle is stopped in a vehicle such as an electric vehicle, and a driving state in a vehicle equipped with an automatic driving function (during automatic driving / manual driving) Can be applied to vehicle lighting systems for various purposes, 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 where the vehicle lamp is off, a constant 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 the light on and off. Further, the present invention can be applied not only to vehicle applications but also to lighting devices and light projection systems using the lighting devices in general.

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

Claims (6)

It is a lighting device for irradiating the front of the vehicle with light.
A light source that emits light and
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,
A light source control device that controls the operation of the light source, and
Including
The image forming unit has a voltage-controlled birefringence type liquid crystal element having a plurality of optical control regions and a pair of polarizing plates arranged opposite to each other with the liquid crystal element interposed therebetween.
The hue of the light incident from one of the polarizing plates in the image forming portion, transmitted through each of the optical control regions, and emitted from the other of the polarizing plates is the hue of the applied voltage in each of the plurality of optical control regions. There are multiple types of different hues depending on the size.
The light source control device operates the light source so as to temporarily reduce the intensity of the light emitted from the light source when the hue of the light is switched from the first hue to the second hue in the image forming unit. To control,
Lighting equipment. The length of the period during which the intensity of the light emitted from the light source is temporarily reduced is 10 msec or less.
The lighting device according to claim 1. The light emitted from the light source is incident on the center of the liquid crystal element from the normal direction and incident on the peripheral portion of the liquid crystal element at an angle.
The lighting device according to claim 1 or 2 . The liquid crystal element has a retardation value of 300 nm or more and 1000 nm or less, which is 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.
The liquid crystal element has a first region, a second region, and a third region in which the thickness of the liquid crystal layer is different from each other.
In the liquid crystal layer, the layer thickness of the first region is relatively smaller than the layer thickness of the second region, and the layer thickness of the second region is relative to the layer thickness of the third region. The difference in layer thickness between the first region and the second region is at least 1 μm or more, and the difference in layer thickness between the second region and the third region is at least 1 μm or more. can be,
In each of the first region, the second region, and the third region, the type of hue of the light obtained differs depending on the magnitude of the applied voltage.
The light distribution pattern in front of the vehicle by the image projected by the projection unit is arranged in the front center of the vehicle, and has a headlight region corresponding to a high beam and a low beam and a bottom of the headlight region. A pedestrian that is located on the side and is provided at least on the left and right sides of the headlight area and the obstacle light distribution area and corresponds to a beam for illuminating the road surface, and exists on the side of the road. Two pedestrian light distribution areas corresponding to beams for illuminating a person or a cyclist, and the headlight area, the obstacle light distribution area, and the left and right side by side above each of the pedestrian light distribution areas are arranged. Includes two roadside sign light distribution regions corresponding to the beam for illuminating the roadside sign present on the side of the road.
The irradiation light to the headlight region is formed by using the first region of the liquid crystal element, and the irradiation light to the obstacle light distribution region and each pedestrian light distribution region is the second region of the liquid crystal element. The regions are formed, and the irradiation light to each roadside marker light distribution region is formed by using the third region of the liquid crystal element.
The lighting device according to any one of claims 1 to 3 . The light distribution pattern further includes a guide sign light distribution region corresponding to a beam for irradiating a guide sign existing on the upper side of the road, and the irradiation light to the guide sign light distribution region is the third region of the liquid crystal element. Formed using
The lighting device according to claim 4 . The lighting device according to any one of claims 1 to 5 .
A detector that detects the position of an object existing in the object space,
A liquid crystal drive device that controls the applied voltage in each of the plurality of optical control regions in the liquid crystal element of the lighting device according to the position of the object detected by the detection unit.
Including light projection system.

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