Headlight device

Abstract

The present invention provides a vehicle headlight device (100), which is installed on a part of a vehicle and irradiates illumination light onto a road surface on which the vehicle is traveling. The headlight device comprises: a light source device (10) for generating the illumination light; and an optical unit (50), which is arranged on the optical axis of the light source device and projects so that the illumination light from the light source device forms a required light distribution. The headlight device is also provided with a polarization direction conversion device (20) on a part of the optical path between the light source device and the optical unit, which can control the light from the light source device according to the irradiation area, including the conversion of the polarization direction, corresponding to the state of the position on the road surface where the illumination light is to be irradiated.

Description

[0001] This application is a divisional application of the invention patent application with application number 201780084479.3, application date 2017.12.12, and name “Headlight Device”. Technical Field

[0002] The present invention relates to a vehicle headlamp device using a solid light emitting element. Background Art

[0003] With the remarkable development of solid-state light-emitting elements such as LEDs in recent years, lighting devices using such solid-state light-emitting elements as light sources have been widely used in various lighting fixtures as a small, lightweight, low-power, environmentally friendly, and long-life light source. Furthermore, they have also begun to be used as vehicle headlight devices with good visibility (recognition) that can be controlled in various ways as vehicle-mounted electronic devices.

[0004] For example, as an existing vehicle headlamp device, according to the following patent document 1, a vehicle headlamp is known, which includes an LED light source array for low beam and an LED light source array for high beam, a first light guide that receives the low beam and the high beam from the LED light sources and collimates them, and a second light guide that diffuses the collimated low beam and the high beam according to a combination of diffusion patterns, and the vehicle headlamp mechanically supports these arrays and light guides in a shell.

[0005] Furthermore, according to Patent Document 2, a vehicle lamp using a liquid crystal unit is disclosed as a lamp that uses a laser light source as a light source and can adjust brightness with a simple structure. Specifically, a non-modulation area that allows laser light to pass through and a modulation area that changes the phase of the polarization component of the laser light by 90 degrees are formed on the liquid crystal unit, and the range of the modulation area and the non-modulation area is adjusted by a liquid crystal driving unit to adjust the brightness of the surrounding light.

[0006] In addition, the following patent document 3 discloses an LED lighting device, especially an LED headlight, which uses a plurality of LEDs as active light sources, and makes the light from the active light sources be emitted according to a predetermined light distribution through a collimating optical unit, a mixing optical unit, a field optical unit, etc. In addition, in particular, claim 25 and paragraph 0036, etc., it is described that as a component for making the light emitted from the active light source reach the mixing optical system in a desired form, other optical elements such as lenses or reflectors for polarizing or shaping light can be configured.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application No. 2008-532250

[0010] Patent Document 2: Japanese Patent Application Publication No. 2015-207390

[0011] Patent Document 3: Japanese Patent Application No. 2013-502679 Summary of the invention

[0012] Technical problem to be solved by the invention

[0013] As LEDs, which are solid-state light sources, improve their luminous efficiency and can be effectively used as luminous light sources in vehicle headlights. However, the above-mentioned prior art and Patent Document 1 are still insufficient in terms of their light utilization efficiency and uniform illumination characteristics, and there is room for improvement.

[0014] In addition, in Patent Document 2, for the non-modulation area and the modulation area pre-formed on the liquid crystal part, the liquid crystal driving part adjusts the range of the modulation area and the non-modulation area to adjust the brightness of the surrounding light, but there is no description of obtaining illumination light with good visibility including its polarization component corresponding to the state of the illumination area of ​​the illumination light. In Patent Document 3, other optical elements such as polarization lenses or reflectors are used as components for making the light emitted from the active light source reach the hybrid optical system in the required form, but there is no description of obtaining illumination light with good visibility including its polarization component.

[0015] To this end, an object of the present invention is to provide a vehicle headlamp device, which can improve the utilization efficiency of light emitted from an LED light source and improve uniform lighting characteristics by using a light source device that can be easily used as a modular planar lighting light source, and generate and irradiate lighting light with better visibility by controlling its polarization component appropriately according to the state of the road surface on which the light is irradiated, etc.

[0016] Technical means of solving problems

[0017] As an embodiment for achieving the above-mentioned purpose, the present invention provides a vehicle headlight device, which is installed on a part of a vehicle and irradiates illumination light on a road surface on which the vehicle is traveling, and comprises: a light source device for generating the illumination light; and an optical unit, which is arranged on the optical axis of the light source device and projects so that the illumination light from the light source device forms a required light distribution. The headlight device is also provided with a polarization direction changing device on a part of the optical path between the light source device and the optical unit. The polarization direction changing device can control the light from the light source device according to the irradiation area, including changing the polarization direction, corresponding to the state of the position on the road surface where the illumination light is to be irradiated.

[0018] Effects of the Invention

[0019] The use of the present invention can achieve good technical effects, that is, by using a light source device that can be manufactured at low cost, is small, easy to modularize, and has high light utilization efficiency, it is possible to provide a vehicle headlight device that has low power consumption, is environmentally friendly, and has a long life, and can control the polarization direction according to a control signal according to the irradiation area, thereby being able to obtain light that is most suitable for the vehicle's driving scene. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is applied to a vehicle headlamp when the vehicle headlamp device according to the embodiment of the present invention is applied to a vehicle headlamp. (a) and a perspective view showing a part of the device in an enlarged manner (b) are shown.

[0021] Figure 2 1 is a perspective view showing the overall structure (a) and the developed structure (b) of a vehicle headlamp device according to an embodiment of the present invention.

[0022] Figure 3 1 and 2 are a side sectional view (a) showing the overall structure of a vehicle headlight device according to a first embodiment of the present invention, and a side sectional view (b) showing the overall structure of a vehicle headlight device according to a modified example.

[0023] Figure 4 It is a perspective view showing the structure of a visible light illumination unit centered around a collimator unit in the vehicle headlamp device according to the first embodiment of the present invention.

[0024] Figure 5 It is a top cross-sectional view showing the operation of the visible light illumination unit centered on the collimating unit in the vehicle headlamp device according to the first embodiment of the present invention.

[0025] Figure 6 It is a partially enlarged cross-sectional view showing the structure and operation of a collimator element of a collimator unit in the vehicle headlamp device according to the first embodiment of the present invention.

[0026] Figure 7 1 and 1. The developed perspective view (a) and its partially enlarged cross-sectional view (b) show the overall structure of a polarization direction changing device of a vehicle headlight device according to Embodiment 1 of the present invention.

[0027] Figure 8 The diagrams show the arrangement configuration (a) of the polarization direction converting device in the vehicle headlamp device according to the first embodiment of the present invention and the arrangement configuration (b) of a modified example thereof.

[0028] Fig. 9 The diagrams are state diagrams for explaining the operation of the polarization direction converting device in the vehicle headlamp device according to the first embodiment of the present invention when no voltage is applied (a) and when voltage is applied (b).

[0029] Fig.10 These are explanatory diagrams for explaining control of a headlight (a) and an illumination area of ​​the headlight (b) in the vehicle headlight device according to the first embodiment of the present invention.

[0030] Fig.11 This is a diagram showing an example of the angular characteristics of the reflectance of p-polarized light and s-polarized light on a material having a refractive index of 1.5 in the vehicle headlamp device according to Example 1 of the present invention.

[0031] Fig.12 1 and 1. A developed perspective view (a) and a side cross-sectional view (b) showing the overall structure of a vehicle headlamp device according to a second embodiment of the present invention.

[0032] Fig.13 1 and 1. are a perspective view (a) and a cross-sectional view (b) for explaining the polarization state of a visible light illumination unit in a vehicle headlamp device according to a second embodiment of the present invention.

[0033] Fig.14 This is a graph showing the transmittance of the polarizing film of the polarizing reflector corresponding to the wavelength of incident light for s-polarized light and p-polarized light at different incident angles in the vehicle headlamp device according to Example 2 of the present invention.

[0034] Fig.15 1 is a characteristic diagram showing the spectral irradiance of sunlight in the vehicle headlamp device according to the second embodiment of the present invention.

[0035] Fig.16 It is a perspective view showing the overall structure of an infrared light illumination unit in a vehicle headlamp device according to a second embodiment of the present invention.

[0036] Fig.17 1 and 1. A developed perspective view (a) and a cross-sectional view (b) showing the internal structure of a vehicle headlamp device according to a third embodiment of the present invention.

[0037] Fig.18 This is a developed perspective view of a modified example (Example 4) of the headlight device of the present invention in a case where the visible light illumination unit is smaller than the LCD panel. DETAILED DESCRIPTION

[0038] The following is a reference to the attached Figure 1 The embodiments (examples) of the present invention are described in detail. The present invention is not limited to the methods described below, and those skilled in the art can implement various changes and modifications within the scope of the technical ideas disclosed in this specification. In addition, in the drawings used to illustrate the present invention, the same symbols are sometimes marked on parts with the same functions, and repeated descriptions are omitted.

[0039] first, Figure 1A vehicle 1 equipped with a vehicle headlamp device using a solid-state light emitting element according to an embodiment of the present invention is shown in a perspective view and a partially enlarged view. Figure 1 (a) shows the entire vehicle 1 equipped with the vehicle headlamp device 100 of the present invention, Figure 1 (b) is an enlarged view of the headlight device portion of the vehicle.

[0040] Figure 2 (a) indicates the above Figure 1 (b) is an overall perspective view of the headlight device 100, Figure 2 (b) The internal structure is shown in an unfolded state. Figure 3 (a) shows a side cross-section of the headlight device 100, and Figure 3 (b) shows a side cross-section of a headlight device according to a modified example.

[0041] (Example 1)

[0042] As shown in these figures, the headlight device 100 basically includes a visible light illumination unit 10 as a light source device and a so-called projection lens 50, wherein the projection lens 50 is an optical system for irradiating the outgoing illumination light from the illumination unit to the space in front of the vehicle 1 and the road surface on which the vehicle 1 is traveling. Furthermore, a reflector 60 may be used instead of the projection lens 50 to constitute a projection optical system, or a projection lens 50 may be used as shown in FIG. Figure 3 (b) shows a structure composed of a projection lens 50 and a reflection mirror 60.

[0043] Furthermore, as can be clearly seen from these figures, in the headlamp device 100 according to the embodiment of the present invention, a polarization direction conversion device 20 for changing (modulating) the polarization direction of the illumination light from the visible light illumination unit 10 is disposed along the optical axis of a portion of the optical path of the illumination light from the visible light illumination unit 10. Figure 3 (a) Compared with Figure 3 The structure shown in (b) deflects the irradiation beam in a predetermined direction by using the reflective mirror 60, and can realize more precise control of the irradiation direction and intensity by using the shape freedom of the reflection surface.

[0044] Next, the details of the components of the headlamp device 100 according to the embodiment of the present invention described above will be described.

[0045] <Visible light illumination unit>

[0046] The visible light illumination unit 10 as the light source device of the present invention is provided with an LED circuit board 11 on the front, on which one or more semiconductor light source elements LED (Light Emitting Diode) as solid light sources and their control circuits, etc., described later, are installed, and a heat sink 12 for diffusing the heat emitted by the LED into the surrounding air is installed on the back of the circuit board. In this example, a total of 15 LEDs are arranged in a 5 (horizontal) × 3 (vertical) grid on the LED circuit board 11. In addition, the following collimation unit 13 is installed on one side of the light-emitting surface of the LED circuit board 11.

[0047] The collimating unit 13 is as follows Figure 4 As shown, the collimating elements 131 (5 (horizontal) × 3 (vertical) = 15 in this example) provided corresponding to the single or multiple LEDs 111 mounted on the LED circuit board 11 are arranged and configured on a plane inside the plate-shaped frame.

[0048] Each collimating element 131 is formed of a resin having light transmittance and heat resistance, such as polycarbonate resin or silicone resin. Figure 5 and Figure 6 As shown, it has an outer peripheral surface 132 in the shape of a convex cone obtained by rotating a cross section of a roughly parabola, and has a recess 134 at its top, and a convex portion (i.e., a convex lens surface) 133 is formed in the central portion of the recess 134. In addition, a convex lens surface 135 convex outwardly (or, a concave lens surface recessed inwardly) is provided in the central portion of its planar portion. In addition, the parabola (outer peripheral surface) 132 forming the conical outer peripheral surface of the collimating element 131 is set within an angle range that allows light emitted from the LED 111 in the peripheral direction to be totally reflected inside it, or a reflecting surface is formed on its surface. The collimating element can be easily and inexpensively manufactured, for example, by conventional molding processing.

[0049] LED 111 is installed at a specified position on the front side of the circuit board 11 for mounting the LED 111. It can be clearly seen from the figure that on the LED circuit board 11, each LED 111 is arranged and fixed relative to the collimating element 131 in a manner such that it is located in the center of the recess 134 of the corresponding collimating element 131.

[0050] With this structure, using the above-mentioned collimating element 131, the light emitted from LED 111, especially the light emitted from its central part toward the upper side (to the right in the figure), is converged into parallel light by two convex lens surfaces 133 and 135 formed on the surface for incident and emitted surfaces of the collimating element 131 as shown by the arrows in the figure. In addition, the light emitted toward the peripheral direction from other parts will also be reflected by the parabola (peripheral surface) 132 forming the conical outer peripheral surface of the collimating element 131, and will be converged into parallel light in the same way. In other words, using the collimating element 131, whose central part constitutes a convex lens and whose peripheral part forms a parabola (peripheral surface) 132, it is possible to extract almost all the light generated by LED 111 as parallel light. As a result, the utilization efficiency of the generated light can be fully improved.

[0051] Next, as can be clearly seen in the figure, a polarization conversion element 14 and a convex lens for controlling light distribution (the lens surface can use a free-form surface with a large degree of freedom in light distribution control, such as a free-form surface) 15 are installed on the front side of the collimating unit 13. In this example, the polarization conversion element 14 is used to select and use specific polarized light.

[0052] More specifically, according to the above Figure 5 As can be clearly seen, the structure of the polarization conversion element 14 is as follows: a light-transmitting component 141 having a parallelogram-shaped column (hereinafter referred to as a parallelogram column) and a light-transmitting component 142 having a triangular column (hereinafter referred to as a triangular column) in cross section are combined, and a plurality of light-transmitting components 141 are arranged in parallel in an array on a plane orthogonal to the optical axis of the parallel light from the collimating unit 13. In addition, polarization beam splitting (hereinafter referred to as "PBS") films and reflection films are alternately arranged on the interface between the adjacent light-transmitting components arranged in the array, and a wave plate 143 with a 1 / 2λ phase is arranged on the exit surface from which the light incident on the polarization conversion element 14 and transmitted through the PBS film is emitted.

[0053] The above-mentioned free-form surface lens 15 is arranged on the exit surface side of the polarization conversion element 14. The exit surface or the incident surface or both the exit surface and the incident surface of the free-form surface lens 15 are composed of free-form surfaces. By using the free-form surface lens 15, the exit direction of light can be controlled by using the surface shape of the lens to obtain illumination light with a desired luminous intensity distribution, for example, Figure 5 As shown by the middle arrow, in order to achieve distant lighting, the distribution of light can be enhanced in the central part.

[0054] In the headlight device 100 having the visible light illumination unit 10 as described above, the light emitted by the LED 111 is converted into substantially parallel light by the collimating unit 13. The light is then converted into linear polarized light by the polarization conversion element 14, and then the polarization direction conversion device 20 described in detail below is used to appropriately change and adjust (control) the polarization direction according to the state of the road surface, etc., and then the required luminous intensity distribution is formed by the free-form surface lens 15, and after being magnified and projected by the projection lens 50 or the projection lens 50 and the reflector 60, it is irradiated onto the space or road surface in front of the vehicle.

[0055] <Polarization direction conversion device>

[0056] The polarization direction changing device 20 is a device that can use the control signal described later to realize the function of appropriately changing and adjusting (controlling) the illumination light from the visible light illumination unit 10 including the polarization direction according to the state of the road surface, etc., in the most suitable driving scene of the vehicle. Specifically, in this embodiment, Figure 7 As shown, the polarization direction changing device 20 is composed of a TN type (Twisted Nematic) LCD (Liquid Crystal Display), and is a device that controls the illumination light at the surface position corresponding to the road surface illuminated by the illumination light from the visible light illumination unit 10 on the LCD, including the polarization direction.

[0057] Specifically, according to Figure 7 As can be clearly seen from (a) and (b), the LCD panel constituting the polarization direction conversion device 20 includes a large number of pixels (for example, 1920 vertically × 1080 horizontally) formed by sandwiching a liquid crystal composition 23 between a pair of glass substrates 22, 22 having orientation films formed on opposite surfaces, so that light incident on one surface passes through each cell and is emitted from the other surface. At this time, by applying a voltage (control signal) between the orientation films arranged oppositely in each pixel, the characteristics of the liquid crystal composition constituting each cell through which light passes can be changed, thereby performing changes and adjustments including the desired polarization.

[0058] Figure 8(a) shows a structure in which polarizing plates 31 and 32 are arranged in front and behind the LCD panel 20, similarly to the case of using a conventional TN type LCD panel. As shown in the figure, the LCD panel 20 is arranged on the optical path of the illumination light from the light source device, i.e., the visible light illumination unit 10. In this example, in order to improve the contrast performance of the obtained image, a polarizing plate 31 (referred to as an "incident side polarizing plate") that increases the polarization degree by transmitting p-polarized light is arranged at the position where the illumination light beam is incident. In addition, similarly, a polarizing plate 32 (referred to as an "exit side polarizing plate") that absorbs p-polarized light is arranged on the light exit side of the LCD panel 20. As a result, the polarization degree of the p-polarized light beam generated by the light source device can be increased by using the incident side polarizing plate 31, and a higher contrast performance can be obtained by using the polarization direction conversion function of the LCD panel. In addition, Figure 8 (b) shows a modified example in which the rear light-exiting side polarizing plate 32 is removed from the LCD panel 20 having the above-described structure.

[0059] Refer to the following Fig. 9 The function (operation) of converting the polarization direction of incident light at each pixel in the polarization direction converting device 20 formed of the TN type LCD panel as described above will be described.

[0060] The polarization direction conversion device 20 composed of the TN type LCD panel as described above is used, as shown in FIG. Fig. 9 As shown in (a), at each pixel, when no voltage is applied between the alignment films, the polarization direction is rotated, for example, from p-polarization to s-polarization (see the hollow arrow in the figure) and passes through the output side polarizer 32 (the so-called "white mode"). Fig. 9 As shown in (b), when a predetermined voltage (V) is applied, the polarization direction does not change. Therefore, the light that remains p-polarized is blocked by the exit-side polarizing plate 32 (so-called "black mode").

[0061] Therefore, in the polarization direction conversion device 20 of the embodiment of the present invention, by setting the transmittance (polarization degree) of the p-polarized light of the output-side polarizer 32 to be larger, that is, setting the extinction ratio of the p-polarized light to be lower (appropriately adjusted), light maintaining the p-polarization can be obtained on the output side. As an example, regarding the transmittance of the output-side polarizer 32, when the transmission or shielding of light is to be controlled, it is preferred to set the transmittance of the p-polarized light to a range of 0.01% to 0.1%. On the other hand, in order to take into account both polarization conversion and contrast (transmittance / absorption), the transmittance of the p-polarized light is preferably in the range of 1% to 40%, and when the purpose is polarization conversion, the transmittance of the p-polarized light is preferably above 80%, and it can also be as shown in FIG. Figure 8 (b) does not use the output side polarizing plate 32. Alternatively, as described above, Figure 8As shown in (b), a structure is adopted in which the light-emitting side polarizing plate 32 is not arranged on the light-emitting side of the LCD panel (it is removed).

[0062] By using the polarization direction conversion device 20, the rotation (twist) angle of the incident specific polarization changes with the voltage applied to the orientation film of each pixel constituting the TN type LCD panel, thereby being able to appropriately select (control) the illumination light beam irradiated onto the road surface according to the condition of the road surface. As a result, the transmittance of the exit side polarizer 32 changes, and the intensity of the illumination light beam changes with the applied voltage. That is, for the illumination light beam to be irradiated onto the road surface, it is possible to perform appropriate control including its polarization direction according to its irradiation position (i.e., the position of the pixel constituting the LCD panel), and to obtain a better illumination light that can improve the visibility of the driver.

[0063] That is, a TN type LCD panel (normally white panel) used as a polarization direction conversion device has the function of rotating the polarization direction when no voltage is applied, from p polarization to s polarization, and the polarization direction does not change when a specified voltage is applied. Furthermore, since the rotation (twist) angle of the incident specific polarization changes with the applied voltage, by appropriately setting (or not setting the polarizer on the output side) the polarization degree (the ratio of the transmittance of a specific polarization to the transmittance of another polarization) of the polarizer on the output side, it is possible to control the polarization direction of the illumination light beam according to the applied voltage. For ease of explanation, the TN type liquid crystal panel is described above, but a TFT (thin film transistor) type liquid crystal panel can also be used as a polarization direction conversion device.

[0064] Next, a technology for controlling the polarization direction and light distribution characteristics of the headlight by using the headlight device 100 of an embodiment of the present invention having the polarization direction changing device 20 as described above, in conjunction with a control signal generated based on the angle of the steering wheel, an external signal from a front monitoring camera and / or the ON and OFF of a control device will be described.

[0065] use Fig.10 A method for controlling the brightness, irradiation range, and polarization degree of a headlight device of a moving vehicle will be described. Fig.10 (a) is a top view of a moving car, and mark 113 is a sensor camera for front monitoring, which detects the presence of vehicles and / or obstacles ahead. In this example, the vehicle headlight device can automatically control the illumination range and / or the intensity of the illumination light of the vehicle headlight device.

[0066] exist Fig.10In the example shown in (b), for the so-called low-beam area that illuminates the range closer to the car, especially in rainy days, in order to reduce the reflection of water on the road surface, the vehicle headlight device irradiates p-polarized light in the low-beam area. On the other hand, in the distant area for identifying the leading vehicle and / or obstacles traveling in the distance, the vehicle headlight device can simultaneously irradiate s-polarized light. In this way, the vehicle headlight device using the embodiment of the present invention can selectively irradiate the optimally polarized light within the necessary light irradiation range, and as a result, it is expected to significantly improve visibility.

[0067] In addition, in the vehicle headlight device of the embodiment of the present invention, the movement of the gaze point is detected by monitoring the rotation angle of the steering gear and / or the pupil position of the driver using a camera, and the irradiation area is automatically changed from 116-1 to 116-2 accordingly. At this time, by modulating the intensity (brightness) of the light beam from the lighting device in accordance with the control signal, the irradiation intensity and irradiation area of ​​the light beam can be set to the optimum even in the process of the viewpoint moving. In the figure (b), the area shown by the dotted line represents the irradiation area when the vehicle headlight device is illuminated but not controlled.

[0068] For example, in bad weather, in order to suppress the reflection of the illumination light of the light source device on the road surface or by raindrops / fog, the illumination light can be converted into linearly polarized light vibrating in a plane perpendicular to the road surface, that is, p-polarized light. On the other hand, in order to improve the visibility of objects in the distant field of vision during driving, Fig.11 That is, by selectively using specific polarized light according to the irradiation object and / or distance, a vehicle headlight device with excellent visibility can be realized.

[0069] As described above, by using the vehicle headlight device, it is possible to provide a vehicle headlight device that uses LEDs, has low power consumption, is environmentally friendly, has a long life, can be manufactured at low cost, is small and easily modularized, has high light utilization efficiency, and can generate illumination light with excellent visibility by selectively irradiating light including light with optimal polarization within the irradiation range, and has good functionality. In other words, it is possible to provide a vehicle headlight device that can obtain light that is most suitable for the driving scene of the vehicle.

[0070] In addition to the above control, the embodiment of the present invention controls the polarization direction, intensity and illumination area according to the control signal. For example, the illumination light, illumination area and polarization direction of the headlight are controlled in coordination with the control signal generated according to the angle of the steering gear, the external signal from the lane monitoring camera and / or the ON and OFF of the control device. As a result, the illumination light of the headlight device changes between the existing high beam and low beam. For example, the illumination light of the headlight device at the surface of the water on the road surface on rainy days adopts p-polarization with less reflection, while for the distant objects, s-polarization is adopted for easy identification. At this time, by modulating the illumination light intensity accordingly, the optimization of the illumination area can be achieved.

[0071] In the above, the headlamp device according to the embodiment of the present invention has been described in detail with a focus on its main components. Now, other embodiments including its modified examples will be described in detail.

[0072] (Example 2)

[0073] Fig.12 (a) and (b) show a structure in which, in the vehicle headlight device 100 having the basic structure as described above, a polarizing reflector or polarizing plate 30 is further provided obliquely on the emission side of the liquid crystal panel (LCD panel) as the polarization direction conversion device 20. With this structure, by controlling the on / off of the LCD panel constituting the polarization direction conversion device 20 to finely control the light distribution, it is possible to achieve illumination that ensures visibility in the distance while suppressing glare to vehicles traveling in the opposite lane or vehicles traveling in the same lane. In addition, by making the LCD panel constituting the polarization direction conversion device 20 a color liquid crystal display element (specifically, in Figure 7 A color filter is set on a glass substrate of the LCD panel, but it is not shown in the figure here). It can use the illumination light to display the driving status information including the speed and direction of the vehicle or other various information about the vehicle driving on the road during the day, not limited to at night.

[0074] These figures show a structure in which the LCD panel 20 is arranged on the optical path of the illumination light from the light source device, i.e., the visible light illumination unit 10, and more specifically, between the free-form surface lens 15 and the projection lens 50 of the visible light illumination unit 10. The reference numeral 21 in the figure indicates an FPC (Flexible Printed Circuits) electrically connected to the LCD panel 20, and the LCD panel 20 is controlled by a control signal output from a control circuit (not shown here) via the FPC 21.

[0075] When the LCD panel 20 is provided in the vehicle headlight device 100, screen burn-in or degradation of its characteristics due to the irradiation of sunlight incident from the outside can be expected. Therefore, as a preventive measure, the present embodiment further arranges a polarizing reflector 30 between the LCD panel 20 and the projection lens 50. In addition, the same effect can be obtained by arranging a reflective polarizing plate at the above position instead of the polarizing reflector 30.

[0076] Next, when information is projected onto the road surface, the distance of the image projected onto the road surface by each pixel of the LCD panel 20 through the projection lens 50 is different, so the focusing performance is reduced. Therefore, in order to reduce the amount of defocusing generated in the image projected onto the road surface, the LCD panel is preferably arranged to be tilted relative to the optical axis. Therefore, in this embodiment, the LCD panel 20 is arranged as follows: Fig.12 As shown, its exit surface is inclined upward at an angle θp (e.g., 10 to 15 degrees) relative to the optical axis. Fig.12 The LCD panel 20 shown is tilted with respect to the optical axis. However, when the LCD panel 20 is used as a normal headlight instead of displaying information on the road surface, the LCD panel may not be tilted with respect to the optical axis.

[0077] At this time, the polarization direction of the light emitted by the LED 111 is rotated by 90 degrees when passing through the LCD panel 20. For this reason, the polarization conversion element 14 is preferably configured as follows: Fig.13 As shown in (a), the light from the visible light illumination unit 10 is converted into linearly polarized light (p-polarized light: polarization parallel to the paper surface) vibrating in a plane parallel to the road surface. Fig.13 As shown in (b), the structure is as follows: a light-transmitting component 141 having a parallelogram-shaped column (hereinafter referred to as a parallelogram column) and a light-transmitting component 142 having a triangular column (hereinafter referred to as a triangular column) are combined, and a plurality of light-transmitting components are arranged in parallel in an array on a plane orthogonal to the optical axis of the parallel light from the collimating unit 13. In addition, PBS films and reflective films are alternately arranged on the interface between the adjacent light-transmitting components arranged in an array, and a wave plate 143 with a 1 / 2λ phase is provided on the exit surface from which the light incident on the polarization conversion element 14 and reflected on the PBS film exits, so that p-polarized light can be irradiated.

[0078] Polarizing mirror 30 (see Fig.12 ) is installed so that its exit surface is tilted downward at an angle θo of more than 45 degrees, preferably 60 degrees, relative to the optical axis. In this embodiment, Fig.12The angle θo shown is set to 60 degrees (θo=60°). By setting the tilt angle θo of the polarizing reflector 30 to be greater than 45 degrees, the reflectivity of the s-polarized light incident from the outside can be increased while maintaining the high p-polarized light transmittance of the polarizing reflector 30. In addition, by tilting the exit surface of the polarizing reflector 30 downward rather than upward relative to the optical axis, as shown in the figure, the angle θs formed by the normal plane of the polarizing reflector and the sunlight incident from the horizontal (optical axis) direction upward can be set larger. Fig.14 The polarizing film transmittance characteristics of the film designed as the polarizing reflector 30 are shown. As can be seen from the figure, the polarizing reflector selectively reduces the transmittance of s-polarized light, and the effect is greater as the incident angle increases. Therefore, the transmittance of the s-polarized component in the sunlight is reduced by the polarizing reflector 30, and the intensity of the sunlight reaching the LCD panel 20 is weakened, which can prevent / suppress the LCD panel 20 from being burned in and the degradation of the characteristics due to sunlight.

[0079] The spectral radiation energy of sunlight is Fig.15 As shown, the polarizing reflector 30 has sufficient energy in areas other than the visible light area of ​​380nm to 780nm, especially in the near infrared and infrared areas above 780nm. Therefore, by making the polarizing reflector 30 have a low transmittance to infrared light, the infrared light component contained in sunlight can be reduced, and the burn-in and degradation of characteristics caused by sunlight can be further prevented. As for the thickness t of the tilted polarizing reflector 30, since it is the main cause of coma and astigmatism, the thickness t is preferably less than 1.5mm, and considering the strength, it is preferably more than 0.6mm.

[0080] In addition, when the LCD panel 20 is provided as described above, the free-form surface of the free-form surface lens 15 provided on the side of the exit surface of the polarization conversion element 14 in the visible light illumination unit 10 is set so as to focus the light incident on the LCD panel 20 in a manner that the distribution is enhanced in the central portion. Thus, the illumination light required by the headlight device can be irradiated to a distant place.

[0081] In the headlight device having the detailed structure as described above, the emitted light of LED 111 is converted into roughly parallel light by the collimating unit 13, and is converted into s-polarized light whose polarization direction is parallel to the paper surface by the polarization conversion element 14. Under the action of the free-form surface lens 15, the emitted light is converged in a manner in which the light intensity of the central part is enhanced and irradiated on the LCD panel 20, and is modulated into image light of various information by the LCD panel 20, and is emitted to the polarization reflector 30 through the LCD panel 20. At this time, the s-polarized light converted by the polarization conversion element 14 is converted into p-polarized light by the LCD panel 20, so that it can efficiently pass through the polarization reflector 30, specifically, more than 80% of the light can be transmitted. The light passing through the polarization reflector 30 is further enlarged and projected by the projection lens 50 and irradiated on the road surface or / and the front.

[0082] Here, in addition to the above-mentioned LCD panel 20, it is also possible to Fig.12 As shown, an infrared light illumination unit 40 for irradiating infrared light is provided. The infrared light illumination unit 40, for example, irradiates infrared light for use by an infrared light sensor (not shown here) for detecting the external condition of the vehicle at night. In the example shown in the figure, the headlight device superimposes the infrared light from the infrared light illumination unit 40 on the illumination light from the visible light illumination unit 10 by using the above-mentioned polarized reflector 30, and irradiates the infrared light as illumination light onto the road surface in front of the vehicle.

[0083] The infrared light illumination unit 40 is as follows Fig.16 As shown in the figure, similarly to the above-mentioned visible light illumination unit, one or more semiconductor infrared LEDs (Light Emitting Diodes) 41 as solid light sources are mounted on the infrared LED collimating unit 42. In the example shown in the figure, as an example, a plurality of (7) infrared LEDs 41 are arranged in a row and fixed to the recessed parts of the infrared LED collimating elements 421 constituting the infrared LED collimating unit 42 (refer to the above-mentioned Figure 6 In addition, although not shown here, the infrared LED 41 is also arranged on a circuit board on which a control circuit, etc. are installed, similarly to the above-mentioned LED 111, and a heat sink for diffusing the heat generated by the LED into the surrounding air is installed on the back of the circuit board, which is a matter of course for those skilled in the art.

[0084] From the above Fig.12It can be clearly seen that the infrared light illumination unit 40 is configured by utilizing the polarizing reflector 30, that is, as an example, it is configured below the optical axis of the polarizing reflector 30 installed with the exit surface tilted at a required angle relative to the optical axis. As a result, the infrared light emitted by the infrared LED 41 can be reflected on the surface of the polarizing reflector 30, superimposed with the illumination light from the visible light illumination unit 10, and illuminated onto the road surface in front of the vehicle. At this time, it is preferred to set it at an angle so that the component of sunlight reflected by the polarizing reflector 30 does not enter the infrared light illumination unit 40.

[0085] In this way, by adopting the second embodiment described in detail above, by installing an infrared light illumination unit capable of irradiating infrared light together with an LCD panel capable of controlling light distribution while preventing degradation due to sunlight, a headlight device with better functionality can be manufactured at a low cost, similar to the first embodiment described above, and the effect of easy miniaturization and modularization can be achieved.

[0086] (Example 3)

[0087] Fig.17 In addition to the structure of the above-mentioned embodiment 1 or 2, an example of a structure in which a shading sheet 60 is provided inside the headlight device is shown. The shading sheet 60 can form a headlight cut-off line (light distribution) required for the light beams (i.e., low beam) from the automobile lamps that intersect each other when vehicles meet. As shown in the figure, the shading sheet 60 is a member formed of a shading member into a predetermined shape, and is arranged and fixed near the focus of the projection lens 50.

[0088] By using the shading sheet 60, it is possible to form an illumination pattern of illumination light such as a light-dark cutoff line required for the oncoming light beam (i.e., low beam) by blocking a portion of the illumination light from the above-mentioned visible light illumination unit 10. In addition, in addition to the fixed type shown in the figure, the shading sheet 60 can also be moved by providing a rotating mechanism such as a motor, and can also be shared with the driving light beam (i.e., high beam), but it is not shown here.

[0089] As described above, according to the third embodiment, a headlamp device with better functionality can be manufactured at low cost, and the headlamp device can be easily miniaturized and modularized.

[0090] (Example 4)

[0091] Fig.18 This is a structural example in which the light source device is shown as a modification of the structure of the above-described embodiment, that is, the visible light illumination unit 10 is smaller than the LCD panel 20 .

[0092] When the visible light illumination unit 10 is smaller than the LCD panel 20, it is necessary to use the free-form surface lens 15 to limit the substantially parallel light emitted from the polarization conversion element 14 according to the size of the LCD panel 20. Fig.18 In the embodiment, the incident surface and the emitting surface of the free-form surface lens 15 are convex, and the distance between the polarization conversion element and the LCD panel 20 is increased to achieve beam constriction. In addition, in order to use the projection lens 50 to emit light from the smaller LCD panel 20 at a wider light distribution angle, the focal length of the projection lens 50 is shortened and the distance between the LCD panel 20 and the projection lens 50 is shortened.

[0093] As described above, by using Example 4, a headlight device with excellent functionality can be manufactured at low cost by using a smaller LED panel, and the headlight device can be easily miniaturized and modularized. By using the vehicle headlight device of the present invention described in detail above, a vehicle headlight device with high light utilization efficiency, low power consumption, environmental friendliness and long life can be realized.

[0094] The vehicle headlight device according to each embodiment of the present invention is described above. However, the present invention is not limited to the above-mentioned embodiments, but also includes various modified examples. For example, in the above-mentioned embodiments, the entire system is described in detail in order to explain the present invention in an easy-to-understand manner, but the present invention is not limited to including all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of a certain embodiment. Moreover, a part of the structure of each embodiment can be added, deleted, or replaced with another structure.

[0095] Description of Reference Numerals

[0096] 100 ... headlight device, 10 ... visible light illumination unit, 11 ... LED circuit board, 111 ... LED, 12 ... heat sink, 13 ... collimation unit, 131 ... collimation element, 132 ... outer peripheral surface, 133 ... convex portion (convex lens surface), 134 ... concave portion, 135 ... convex lens surface, 14 ... polarization conversion element, 143 ... wave plate with 1 / 2λ phase, 15 ... free-form surface lens, 20 ... polarization direction conversion device (TN type LCD panel (liquid crystal panel) )), 30...polarizing reflector, 40...infrared light illumination unit, 41...infrared LED, 42...infrared LED collimating unit, 50...projection lens, 60...reflector, 111...road, 110...car, 113...front monitoring camera, 115...the illumination area near the vehicle of the headlight device, 116-1...the illumination area far away from the vehicle of the headlight device (before control), 116-2...the illumination area far away from the vehicle of the headlight device (after control), 117...the vehicle in front.

Claims

1. A headlight device for a vehicle, characterized in that: include: a light source device for generating light; An optical unit, which is arranged on the optical axis of the light source device and projects the illumination light from the light source device so as to form a required light distribution; and a polarization direction changing device for changing the polarization direction of light from the light source device, On the optical axis of the light emitted from the light source device, the light source device, the polarization direction changing device and the optical unit are arranged in this order, The polarization direction changing device can control the light from the light source device including changing the polarization direction according to the state of the road surface, so as to selectively use specific polarized light according to the irradiation object and / or the irradiation distance.

2. The headlight device according to claim 1, characterized in that: The light source device comprises: light source; a polarization conversion element for performing polarization conversion on light from the light source; and a collimating element disposed between the light source and the polarization conversion element, On the optical axis of light emitted from the light source device, the light source, the collimating element, the polarization conversion element, the polarization direction conversion device, and the optical unit are arranged in this order.

3. The headlight device according to claim 1, characterized in that: A polarizing plate or a reflecting mirror is further provided between the polarization direction changing device and the optical unit so that the emission surface is tilted downward at a predetermined angle.

4. The headlight device according to claim 1, characterized in that: A free-form surface lens is also arranged on one side of the exit surface of the light source device.

5. The headlight device according to claim 1, characterized in that: The polarization direction changing device is composed of a transmissive liquid crystal panel.

6. The headlight device according to claim 1, characterized in that: The size of the exit surface of the light source device is smaller than the size of the incident surface of the polarization direction changing device.

7. The headlight device according to claim 5, characterized in that: The liquid crystal panel constituting the polarization direction changing device has a structure in which no light-emitting side polarizing plate is provided.

8. The headlight device according to claim 5, characterized in that: The exit-side polarizing plate of the liquid crystal panel constituting the polarization direction changing device has an extinction ratio smaller than a polarization extinction ratio of the incident-side polarizing plate.

9. The headlight device according to claim 5, characterized in that: The liquid crystal panel constituting the polarization direction changing device is a color liquid crystal display element.

10. The headlight device according to claim 1, characterized in that: The optical unit is composed of either or both of a projection lens and a reflection mirror.

11. The headlight device according to claim 1, characterized in that: Also included is an infrared light emitting unit for generating infrared light.

12. The headlight device according to claim 11, characterized in that: The infrared light emitting unit comprises: One or more semiconductor infrared elements for emitting the infrared light; and The infrared collimating section includes one or more infrared collimating elements arranged on the light emission axes of the semiconductor infrared elements and configured to convert the light emitted from the semiconductor infrared elements into substantially parallel light.

13. The headlamp device according to claim 12, characterized in that: A polarizing reflector is further provided between the polarization direction changing device and the optical unit in such a manner that the emission surface is tilted downward at a predetermined angle. The infrared light emitting unit is configured such that the emitted infrared light is reflected on the emission surface of the polarizing reflector and then irradiated in a predetermined direction through the optical unit.

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