JP7077392B2 - Head-up display device - Google Patents

Description

The present invention relates to techniques such as a light source device and an image display device. The present invention also relates to a light source device suitable as a light source for an image display device such as an in-vehicle head-up display (HUD) device. The present invention also relates to a planar light source using a solid-state light emitting element and a light source device that can be used as illumination.

With the remarkable development of solid-state light emitting elements such as light emitting diodes (LEDs) in recent years, lighting devices that use these elements as light sources are compact and lightweight, have low power consumption, and are excellent in environmental protection. It has been widely used in various lighting fixtures as a long-life light source.

Conventionally, for example, according to Japanese Patent Application Laid-Open No. 2016-33668 (Patent Document 1), as a light source device for a projector (projection type display device), a semiconductor light source device having a simple configuration is used, and a semiconductor light emitting device can be efficiently used. A semiconductor element light source device that cools and emits bright light is already known.

Japanese Unexamined Patent Publication No. 2016-33668

However, in the semiconductor light source device disclosed in the above-mentioned prior art (Patent Document 1), mainly by efficiently cooling the semiconductor light emitting device, it is possible to prevent the device from short-circuiting and failing to function. It provides a semiconductor element light source device that emits light efficiently and brightly. Further, the light emitted from the element is focused by using a single lens or a plurality of lenses provided facing the element. Therefore, in the prior art, it is possible to improve the luminous efficiency by the LED which is a semiconductor light source. However, it is difficult to sufficiently collect and use the emitted light, and in particular, in projectors that require high light emission performance, HUD devices, headlamp devices for vehicles, etc., the light utilization efficiency characteristics. And the uniform lighting characteristics were still inadequate, and there was room for various improvements.

Therefore, an object of the present invention is to provide a light source device that is compact and lightweight and has high utilization efficiency of emitted light.

A typical embodiment of the present invention is a light source device or the like, and is characterized by having the following configurations. The light source device of one embodiment includes a light source unit including a plurality of semiconductor light source elements that generate light, and a collimeter including a plurality of each collimator element arranged on the light emitting axis of each of the plurality of semiconductor light source elements. The light guide body comprises a light guide body arranged on the emission side of the collimator, and the light guide body has an incident portion having an incident surface for incident light on the light emitting axis from the semiconductor light source element and the light. It includes an emitting portion having an emitting surface for emitting, and has a free curved shape for realizing a predetermined light distribution control on at least one of the incident surface and the emitting surface.

According to a typical embodiment of the present invention, it is possible to provide a light source device that is compact and lightweight and has high utilization efficiency of emitted light.

As an example to which the light source device according to the embodiment (Embodiment 1) of the present invention is applied, it is a developed perspective view which shows the whole overview of the head-up display device including the image display device. It is a developed perspective view which shows the overview of the internal structure of a video display device. It is a perspective view which shows an example of the internal structure of a light source device. It is a partially enlarged sectional view which shows the structure and operation of the collimator and the polarization conversion element which make up a light source device. It is a partially enlarged sectional view which shows the comparative example of the structure of a collimator and a polarization conversion element. It is a perspective view which shows the other structural example of the internal structure of a light source device. It is the side view which shows the synthetic diffusion block of a light source apparatus, and is the partially enlarged sectional view which magnified a part thereof. It is an overall perspective view which shows the details of the light guide body which constitutes a light source device, the sectional view thereof, and the partially enlarged sectional view which shows the details of the sectional view. It is a schematic diagram which shows the reflection surface and the articulation surface enlarged for the explanation of a light guide body. It is a top view and a side view which shows the reflection surface and the articulation surface enlarged for the explanation of a light guide body. It is a side view which shows the comparative example of a light guide body. It is a side view which shows the modification of the light guide body. It is a side view which shows the other modification of a light guide body. It is a side view which shows the further modification example of a light guide body. It is a side view which shows the modification of the light guide body using a functional scattering surface. It is a figure including the characteristic curve explaining a functional scattering surface. It is a figure for demonstrating the effect by a functional scattering surface. It is a figure for demonstrating an example of processing of a light guide body. It is an overall external perspective view of the image display device which shows the other example of the image display device to which the light source device is applied. It is a top view and a side view which shows the modification of the light guide body for a larger liquid crystal display device. It is a side view which shows the modification of the light guide body of FIG. It is a top view which shows the specific example of the texture formed on the reflective surface of a light guide body. It is an overall side view which shows an example of the structure of the larger-sized light source device which combined the light guide body. It is an overall side view which shows an example of the structure of the light source apparatus which consists of a light guide body which includes a plurality of light incident parts. It is a top view and a side view which shows an example of the structure which formed the light guide body by a polarization conversion element. It is a figure which shows the schematic structure when the vicinity of the driver's seat of the vehicle which is equipped with the HUD device which includes the light source device and the image display device of Embodiment 2 of this invention is seen from the side. It is a figure which shows the functional block composition of the said HUD apparatus. It is explanatory drawing which shows the outline of the structure in the HUD apparatus of the comparative example, and the behavior and the problem when the outside light is incident. It is explanatory drawing which shows the outline of the structure in the HUD apparatus of Embodiment 2, the behavior when the outside light is incident, and the like. It is a figure which shows the structural outline of the said image display apparatus, adjustment optical system and the like. It is a perspective view which shows the appearance of the said image display device. It is a perspective view which shows one Example of the internal structure of the said light source apparatus. It is a partially enlarged sectional view which shows the structure of the light source part of the said light source device, an LED collimator, a polarization conversion element and the like, and light distribution. It is a perspective view which shows the structure of the said polarization conversion element. It is a top view which shows the arrangement composition example of a plurality of LED elements with respect to the said polarization conversion element. It is a figure which shows the arrangement configuration example of a plurality of LED elements, etc. of the said light source device. It is a figure which shows the structure of the comparative example with respect to the arrangement composition example of the plurality of LED elements of the light source device. It is a top view and the side view which shows the 1st Embodiment of the plurality of light source elements (in the case of N = 5) of the light source apparatus of Embodiment 2. FIG. It is a top view and the side view which shows the 2nd Embodiment of the plurality of light source elements (in the case of N = 6) of the light source apparatus of Embodiment 2. FIG. It is a perspective view and the side view which shows the whole detailed structure of the light guide body of the said light source device. It is a side view which shows the detail of the reflection part of the said light guide body. It is sectional drawing which shows the structure of the orientation control in the light source apparatus of Embodiment 2. FIG. It is a figure which shows the structure of the light distribution control plate of the said light source device. It is explanatory drawing which shows the formula and the coefficient of the free curved surface in the light source apparatus of Embodiment 2. It is sectional drawing which shows the schematic structure of the light guide body and the like in the light source device and the image display device of the 1st modification of Embodiment 2. It is sectional drawing which shows the schematic structure of the light guide body and the like in the light source device and the image display device of the 2nd modification of Embodiment 2. It is a perspective view and a partial sectional view which shows the structure of the light source device and the image display device of the 3rd modification of Embodiment 2. FIG. It is a perspective view which shows the whole of the light guide body in the 3rd modification. It is explanatory drawing which shows the formula and the coefficient of the free curved surface of the said light guide body. It is a perspective view which shows the structure of the light source device and the image display device of the 4th modification of Embodiment 2. It is a perspective view which shows the structure of the light source device and the image display device of the 5th modification of Embodiment 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In principle, the same parts are designated by the same reference numerals in all the drawings for explaining the embodiments, and the repeated description thereof will be omitted. Further, the parts described with reference numerals in one figure may be referred to by the same reference numerals without being shown again in the explanation of other figures.

(Embodiment 1)
A light source device and the like according to an embodiment of the present invention (referred to as the first embodiment) will be described with reference to FIGS. 1 to 25.

[1-1: HUD device]
FIG. 1 is a developed perspective view showing an example in which the light source device according to the embodiment (Embodiment 1) of the present invention described in detail below is applied to the HUD device 1 as an example. The image display device 30 including the light source device according to the embodiment of the present invention is attached to a part of the outer case 155 which is the housing thereof, and the concave mirror 141, the distortion correction lens 143, and the like are housed inside the case. Has been done. An opening is formed on the upper surface of the upper exterior case 151 to project the image light toward the windshield (not shown), and the opening is covered with the antiglare plate 152 (glare trap). ing. Further, the concave mirror drive unit 142 is configured by an electric motor or the like for adjusting the position of the concave mirror 141.

It is obvious to those skilled in the art that in the HUD device 1 having such a configuration, the image light emitted from the image display device 30 is projected onto the windshield of the vehicle via the display distance adjusting mechanism and the mirror drive unit. Let's do it. Further, by adjusting the angle of the concave mirror 141, the position of projecting the image onto the windshield may be adjusted so that the display position of the virtual image seen by the driver can be adjusted in the vertical direction. The content to be displayed as a virtual image is not particularly limited, and for example, vehicle information, navigation information, an image of a landscape in front taken by a camera image (surveillance camera, around viewer, etc.) not shown can be appropriately displayed.

[1-2: Video display device]
Subsequently, the above-mentioned video display device 30 will be described in detail below with reference to FIG. The image display device 30 is configured by, for example, accommodating an LED element, a collimator, a synthetic diffusion block, a light guide body, and the like, which will be described in detail later, inside a light source device case 11 made of plastic or the like. A liquid crystal display element (LCD) 50 is attached to the upper surface of the image display device 30, and an LED element which is a semiconductor light source and an LED substrate 12 on which a control circuit thereof is mounted are attached to one side surface thereof. ing. Further, a heat sink (radiating fin) 13 for cooling the heat generated by the LED element and the control circuit is attached to the outer surface of the LED substrate 12.

Further, in the above-mentioned video display device 30, the liquid crystal display element 50 attached to the upper surface of the light source device case 11 includes a liquid crystal display panel frame 51, a liquid crystal display panel 52 attached to the liquid crystal display panel frame 51, and further. It is composed of a flexible wiring board (FPC) 53 electrically connected to the liquid crystal display panel 52.

As is clear from the above description, for example, in the case of a HUD device, since it is incorporated in a narrow space called a dashboard of a vehicle, the embodiment of the present invention constituting the HUD device 1 is used. For the image display device 30 including the light source device, it is particularly preferable that the image display device 30 is small in size and highly efficient due to modularization, and can be suitably used.

[1-3: Optical system]
FIG. 3 shows the configuration of an optical system having a polarization function as an example of an optical system housed inside the image display device 30, that is, in the case 11 of the light source device. That is, a plurality of (two in this example) LED elements 14a and 14b constituting the light source according to the embodiment of the present invention are attached to the LED collimator 15 at a predetermined position.

Although details will be described later, the light emitting side of the LED collimator 15 has a polarization beam splitter (PBS) and a phase plate arranged symmetrically with respect to the central axis of the LED collimator 15. A polarization conversion element 21 made of an optical member such as the above is provided. Further, a rectangular synthetic diffusion block 16 is provided on the emission side of the polarization conversion element 21. That is, the light emitted from the LED element 14a or the LED element 14b becomes parallel light by the action of the LED collimator 15 and enters the polarization conversion element 21, and after being converted into the desired polarized light by the polarization conversion element 21, the light is converted into the desired polarized light. It is incident on the synthetic diffusion block 16.

Further, as shown in FIG. 3, a light guide body 17 having a substantially triangular cross section is provided on the emission surface side of the synthetic diffusion block 16 via the first diffusion plate 18a, as shown in FIG. 3, for example. A second diffuser plate 18b is attached to the upper surface thereof. As a result, the horizontal light of the LED collimator 15 is reflected upward in the drawing by the action of the light guide body 17 and is guided to the incident surface of the liquid crystal display element 50. At that time, the strength is made uniform by the first diffusion plate 18a and the second diffusion plate 18b.

Subsequently, the main parts constituting the light source device according to the embodiment of the present invention described above will be described below including the details of each part.

[1-4: LED element, LED collimator]
As shown in FIG. 4, the light source device according to the embodiment of the present invention includes an LED element 14 (14a, 14b) formed on the LED substrate 12, which is a single or a plurality of semiconductor light emitting elements, and the LED element. It is composed of an LED collimator 15 arranged so as to face the light emitting surface of 14. The LED collimator 15 is made of a translucent resin having excellent heat resistance such as polycarbonate, and as shown in FIG. 4, the LED collimator 15 is centered on the LED element 14 on the LED substrate 12. It is formed so as to surround the surroundings. More specifically, the LED collimator 15 has a conical outer peripheral surface 156 obtained by rotating a substantially parabolic cross section, and a recess 153 having a predetermined curved surface at the top thereof on the incident side of light. Is formed, and the LED elements 14 (14a, 14b) are arranged in a substantially central portion thereof. The parabolic surface (reflector portion) forming the conical outer peripheral surface 156 of the LED collimator 15 is emitted from the LED element 14 (14a, 14b) in the peripheral direction together with the curved surface of the concave portion 153, and is inside the concave portion 153. The light that passes through the air and enters the inside of the LED collimator 15 is set to be incident within the range of the angle that is totally reflected on the paraboloid. As described above, by utilizing the total reflection on the paraboloid, the apparatus is manufactured at a lower cost because a step such as forming a metal reflection film on the outer peripheral surface 156 of the LED collimator 15 is not required. It becomes possible.

Further, an incident surface (lens surface) 157 having a predetermined curved surface is formed in the central portion of the concave portion 153 of the LED collimator 15, and a convex portion (lens) formed on the facing surface (exit surface) 154. Surface) Together with 158, a so-called convex lens having a light-collecting action is formed. The convex portion 158 may be formed as a flat surface or a concave lens surface recessed inward. That is, the LED collimator 15 has a function of a condenser lens that collects light emitted from the LED collimator 15 on the emission surface side in the central portion of the outer shape of the cone, and also has an outer peripheral surface 156 (reflector portion) thereof. Similarly, it has a function of condensing the light emitted from the LED element 14 (14a, 14b) in the peripheral direction and guiding it to the emission surface side.

As shown in FIG. 4, the LED substrate 12 has the LED elements 14 (14a, 14b) on the surface of the LED collimator 15 located at the center of the recess 153, respectively. Placed and fixed.

According to this configuration, among the light radiated from the LED element 14 (14a, 14b), the light radiated from the central portion thereof toward the emission optical axis (to the right in the drawing) is the above-mentioned LED collimator. 15 causes parallel light to be condensed by the two convex lens surfaces 157 and 158 forming the outer shape of the LED collimator 15, as shown by an arrow in the drawing, and light radiated from other parts toward the periphery. Is reflected by the radial surface forming the conical outer peripheral surface (reflector portion) 156 of the LED collimator 15, and is similarly condensed into parallel light. In other words, according to the LED collimator 15 in which a convex lens is formed in the central portion thereof and a paraboloid is formed in the peripheral portion thereof, almost all of the light generated by the LED element 14 (14a, 14b) is parallel light. It is possible to take out the light as an LED, and it is possible to improve the utilization efficiency of the generated light.

Further, in this embodiment, a polarization conversion element 21 composed of a polarizing beam splitter and an optical member such as a phase plate is provided on the light emitting side of the LED collimator 15, and these elements are also shown in the drawings. As is clear, they are arranged symmetrically with respect to the central axis of the LED collimator 15 (see the alternate long and short dash line in the drawing). Further, a rectangular synthetic diffusion block 16 is provided on the emission side of the polarization conversion element 21. That is, the light emitted from the LED element 14a or the LED element 14b becomes parallel light by the action of the LED collimator 15 and is incident on the synthetic diffusion block 16.

[1-5: Comparative example]
As described above, according to this configuration, as is clear from the comparison with the comparative example of FIG. 5, it is thinner and the cost is reduced by reducing the amount of material used, and the light source device is downsized. to enable. Since the thinning of the polarization conversion element prevents an increase in the optical path length difference between the light flux reflected by the PBS film and the light flux transmitted, it is difficult for the difference in the luminous flux shape between the two due to the difference in the optical path length to occur. In a system using a light source and an LED collimator, it is effective in eliminating the non-uniformity of the luminance distribution caused by the difference in the shape of the luminous flux.

[1-6: Optical system]
Further, FIG. 6 shows another configuration example of the optical system housed inside the image display device 30, that is, in the case 11 of the light source device. That is, a plurality of (four in this example) LED elements 14a, 14b, 14c, 14d constituting the light source according to the embodiment of the present invention are attached to the LED collimator 15 at a predetermined position.

In this embodiment, the rectangular synthetic diffusion block 16 is provided on the light emitting side of the LED collimator 15, but the above-mentioned polarization conversion element 21 is not provided, and therefore the LED element is not provided. The light emitted from 14 (14a, 14b, 14c, 14d) is not polarized, but becomes parallel light by the action of the LED collimator 15 and is incident on the synthetic diffusion block 16.

Further, on the emission surface side of the synthetic diffusion block 16, as shown in FIG. 6, for example, a light guide body 17 having a substantially triangular cross section is provided via a first diffusion plate 18a. A second diffuser plate 18b is attached to the upper surface. As a result, the horizontal light of the LED collimator 15 is reflected upward in the drawing by the action of the light guide body 17 and is guided to the incident surface of the liquid crystal display element 50. At that time, it is the same as the above-mentioned example that the strength is made uniform by the first diffusion plate 18a and the second diffusion plate 18b.

[1-7: Synthetic diffusion block]
Subsequently, the synthetic diffusion block 16, which is another component of the video display device 30, will be described with reference to FIG. 7. Note that FIG. 7A shows the side surface of the synthetic diffusion block 16, and FIG. 7B shows a partially enlarged cross section of the synthetic diffusion block 16 which is partially enlarged.

As is clear from FIG. 7, in the synthetic diffusion block 16 formed of a translucent resin such as acrylic, a large number of textures 161 having a substantially triangular cross section are formed at a pitch S on the exit surface thereof. By the action of the texture 161 the light emitted from the LED collimator 15 is diffused in the vertical direction of the light incident portion (plane) 171 of the light guide body 17 described below. Then, due to the interaction between the substantially triangular texture 161 and the diffusers 18a and 18b described below, even if the LED collimators 15 are arranged discretely, the light emitting portion 173 of the light guide body 17 can be used. It is possible to make the intensity distribution of the emitted light uniform. Further, in the HUD device, the display position of the virtual image seen by the driver can adjust the angle of the concave mirror 141 as described above, but the left / right position adjustment function is generally not provided, and the virtual image is displayed. Since confirmation is premised on binocular vision, it is desirable that the area where the virtual image can be visually recognized is wider in the left-right direction than in the up-down direction. In order to realize the above configuration, it is effective to widen the direction corresponding to the left-right direction of the virtual image of the light distribution angle of the light source device as compared with the front-back direction thereof. In this configuration, the area where the virtual image can be recognized is widened in the left-right direction by setting the direction in which the texture 161 of the synthetic diffusion block is diffused and the orientation angle is widened to the left-right direction of the virtual image display.

In particular, according to the texture 161 described above, the diffusion direction of light can be limited to the side surface direction of the light guide body, and the diffusivity in the side surface direction can be controlled. It is possible to weaken the isotropic diffusivity of the plates 18a and 18b, and as a result, the light utilization efficiency is improved and a light source device having good characteristics can be realized. In this example, as an example of the substantially triangular texture 161, an example in which the angle γ = 30 degrees and the formation pitch S = 0.5 mm is shown.

[1-8: Light guide body]
Subsequently, the details of the light guide body 17 constituting the image display device 30 will be described below with reference to FIG. The light guide 17 has a function of internally reflecting and refracting light taken from an incident surface as parallel light from the above-mentioned light source device to guide it in a desired direction and extracting it as planar light having a desired area. Has.

8 (a) is a perspective view showing the entire light guide body 17, FIG. 8 (b) is a cross section thereof, and FIGS. 8 (c) and 8 (d) show details of the cross section. It is a part enlarged sectional view. The light guide body 17 is a member formed of a translucent resin such as acrylic into a substantially triangular cross section ((b) in FIG. 8), and as is clear from (a) in FIG. , A light guide body light incident portion (plane) 171 facing the emission surface of the synthetic diffusion block 16 via the first diffuser plate 18a, a light guide body light reflection portion (plane) 172 forming a slope, and a second. The light guide body light emitting portion (plane) 173 facing the liquid crystal display panel 52 of the liquid crystal display element 50 is provided via the diffuser plate 18b of 2. In addition, it may be described as an incident part 171 (incident surface), a reflecting part 172 (reflecting surface), an emitting part 173 (exiting surface), etc., respectively.

As shown in detail in FIGS. 8 (c) and 8 (d), which are partially enlarged views thereof, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately serrated on the reflecting portion 172 of the light guide body 17. It is formed in a shape. The reflective surface 172a (a line segment rising to the right in the drawing) forms an angle αn (n: a natural number, 1 to 130 in this example) with respect to the horizontal plane indicated by the alternate long and short dash line in the drawing. As an example, here, the angle αn is set to 43 degrees or less (however, 0 degrees or more).

On the other hand, the connecting surface 172b (a line segment descending to the right in the drawing) forms an angle βn (n: a natural number, 1 to 130 in this example) with respect to the reflecting surface 172a. That is, the connecting surface 172b of the reflecting portion 172 is inclined at an angle that becomes a shadow in the range of the half-value angle of the scatterer described later with respect to the incident light. As will be described in detail later, the angle αn (α1, α2, α3, α4 ...) forms the elevation angle of the reflecting surface, and the angle βn (β1, β2, β3, β4 ...) is connected to the reflecting surface 172a. It forms a relative angle with 172b, and as an example, it is set to 90 degrees or more (however, 180 degrees or less). In this example, the angle β1 = β2 = β3 = β4 = ... = β22 = ... β130.

[1-9: Light guide body (2)]
9 and 10 show a schematic diagram in which the sizes of the reflecting surface 172a and the connecting surface 172b are relatively enlarged with respect to the light guide body 17 for the sake of explanation. In the incident portion 171 of the light guide body 17, the main light ray is deflected by an angle δ in the direction in which the incident angle increases with respect to the reflecting surface 172a ((b) in FIG. 10). That is, the incident portion 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the emission surface of the synthetic diffusion block 16 is diffused and incident through the first diffusion plate 18a, and as is clear from the drawing, it is slightly bent upward by the incident portion 171. It reaches the reflecting portion 172 while (deflating) (compared to the example of FIG. 11).

In the reflecting portion 172, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape, and the diffused light is totally reflected on each reflecting surface 172a and heads upward, and further. Is incident on the liquid crystal display panel 52 as parallel diffused light via the emitting portion 173 and the second diffuser plate 18b. Therefore, the angle αn (α1, α2, ...) Which is the elevation angle of the reflecting surface is set so that each reflecting surface 172a has an angle equal to or higher than the critical angle with respect to the diffused light, while the reflecting surface 172a is set. The angle βn (β1, β2, ...), Which is a relative angle between the and the connecting surface 172b, is a constant angle as described above, and the reason will be described later, but more preferably an angle of 90 degrees or more (βn ≧). It is set to 90 °).

[1-10: Comparative example]
With the above-mentioned configuration, each reflecting surface 172a is configured so that the angle is always equal to or higher than the critical angle with respect to the diffused light. It is possible to realize a light source device provided with a light guide body, which enables reflection, guides the light in a desired direction at low cost, and has a function of extracting as planar light having a desired area. On the other hand, as shown in FIG. 11 as a comparative example, when there is no bending (polarization) of the main light beam at the incident portion of the light guide body 17, a part of the diffused light has a critical angle with respect to the reflecting surface 172a. Since it becomes the following and a sufficient reflectance cannot be secured, a light source device having good characteristics (bright), that is, an image display device cannot be realized.

However, according to the shape of the reflecting portion 172 of the light guide body 17 described above, it is possible to satisfy the total reflection condition of the main light, it is not necessary to provide a reflecting film such as aluminum on the reflecting portion 172, and the light is efficiently reflected. It is possible to realize a bright light source at a lower cost without the need for vapor deposition work of an aluminum thin film that accompanies an increase in manufacturing cost. Further, the angle βn, which is each relative angle, is set so that the connecting surface 172b becomes a shadow with respect to the light diffused by the synthetic diffusion block 16 and the diffusion plate 18a by the main light beam L30. As a result, by suppressing the incident of unnecessary light on the connecting surface 172b, the reflection of unnecessary light can be reduced, and a light source device having good characteristics can be realized.

Further, according to the light guide body 17 described above, as shown in FIG. 9, the lengths of the connecting surface 172b (Lc1, Lc2, Lc3, ...) And the reflecting surface 172a (Lr1, Lr2, Lr3, ...) And Since the length of the exiting portion 173 in the optical axis direction can be freely changed by appropriately setting the ratio, the size (plane size) of the emitting portion 173 is displayed on the liquid crystal display with respect to the incident portion 171. It is possible to realize a light source device that is suitable for a device such as a panel 52 and can be appropriately changed to a required size (plane size). This also means that it is possible or possible to shape the emitting unit 173 to a desired shape without depending on the arrangement shape of the LED elements 14 (14a, 14b) constituting the light source, that is, a desired shape. A planar light source having a shape can be obtained. Further, it leads to securing the degree of freedom in the design including the arrangement of the LED elements 14 (14a, 14b) constituting the light source, which is advantageous for the miniaturization of the entire device.

[1-11: Modification example]
FIG. 12 shows an example of the above modification. As is clear from the drawings, in this modification, the incident portion 171 of the light guide body 17 is a flat surface perpendicular to the light emitted from the LED collimator 15, unlike the curved surface described above. The incident surface is provided with an auxiliary light guide body 17a having a vertical triangular cross section for slightly bending (deflecting) the incident light upward.

Further, in FIG. 13, as another modification, the incident portion 171 of the light guide body 17 is made a vertical plane, and the LED collimator 15 is slightly tilted so that the incident light is slightly bent upward. The configuration to be (biased) is shown. That is, the same effect as described above can be obtained by these modified examples.

[1-12: Modification example]
Further, as shown in FIG. 14, by appropriately setting the connecting surface 172b constituting the reflecting portion 172 (in this example, light is not reflected by a part of the reflecting surface 172a in the central portion thereof). For example, in the emission portion 173 of the light guide body 17, the ratio (Lr / Lc) of the reflecting surface 172a and the connecting surface 172b can be significantly changed depending on the location. Thereby, in the illustrated example, it is shown that the light emitted from the emitting portion 173 of the light guide body 17 is divided into left and right in the direction of the optical axis. Such a configuration may be suitable, for example, when the illumination light from the HUD device is separated vertically or horizontally without loss. Further, by appropriately adjusting the above ratio (Lr / Lc), it is possible to partially strengthen or weaken the reflected light.

[1-13: Modification example]
In addition, in the above-mentioned light guide body 17, as shown in FIG. 15, the above-mentioned functional scattering surface is provided and formed on at least one of the incident portion 171 and the exit portion 173, respectively. It is also possible to omit either or both of the diffuser plates 18a and 18b shown in FIG.

This functional scattering surface is intended to reduce unnecessary divergent light components by reducing the surface roughness of components (fine components) having a high spatial frequency. FIG. 16B shows a surface roughness spatial frequency component of a normal scattering surface, and FIG. 16A shows a surface roughness spatial frequency component of a scattering surface having more preferable scattering characteristics. In the same drawing, the solid line is the surface roughness spatial frequency component measured in the vertical direction with respect to the drawing of the entrance surface or the exit surface of the light guide in FIG. 15, and the broken line is the entrance surface or the entrance surface of the light guide in FIG. The surface roughness spatial frequency component when measured in the direction parallel to the drawing of the emission surface is shown.

The surface roughness spatial frequency distribution of a normal scattering surface shows a distribution along the reciprocal of the spatial frequency (1 / f) as shown in FIG. 16 (b). On the other hand, the spatial frequency distribution of the more preferable surface roughness becomes a low value in the low frequency region of the spatial frequency of 10 / mm or less and the high frequency region of 100 / mm or more, as shown in FIG. 16 (a). Since the low frequency component of the surface roughness spatial frequency is small and the medium frequency component is moderately present, a light source with less uneven scattering can be realized. Further, since the high frequency component of the surface roughness spatial frequency is small, the scattering angle of the scattered light is not large and the unnecessary light component is reduced, so that a light source having a bright and uniform luminance distribution can be realized. In order to realize such characteristics, further, the functional scattering surface has a spatial frequency component of 10 nm or less, especially in a high frequency region of 100 / mm or more, in the range of visible light (wavelength 400 nm or more). It was confirmed by experiments that the generation of unnecessary scattering components can be prevented. On the other hand, as shown in FIG. 16B, a normal scattering surface scatters light outside the direction in which it can be used as a light source, so that a bright light source cannot be realized.

Further, within the above range, the scattering angle can be adjusted by adjusting the spatial frequency component as shown by the solid line and the broken line in FIG. 16 (a). As described above, in the HUD device, it is desired that the area where the virtual image can be visually recognized is wide in the horizontal direction with respect to the vertical direction. Therefore, the orientation angle of the light source device is set to the scattering angle so that the corresponding direction is wide. It was adjusted. Specifically, the spatial frequency distribution of the surface roughness measured in the vertical direction with respect to the drawings of the entrance surface and the emission surface of the light guide body shown in FIG. 15 is the distribution shown by the solid line in FIG. 16 (a). As shown by the broken line in the drawing, the spatial frequency distribution of the surface roughness measured in the direction perpendicular to the drawing has a distribution in which the high frequency component is relatively smaller than the solid line.

By adopting the above-mentioned functional scattering surface, the degree of freedom in controlling the incidence and emission of light on the entrance surface and the emission surface of the light guide 17 is increased, and the brightness unevenness of the light from the light source device is increased. It will be possible to reduce the number of fine-grained controls according to the characteristics of the optical system device (in this example, the liquid crystal display element 50 as an example) arranged on the downstream side thereof, and further, it will be advantageous in reducing the cost of the device.

Further, as shown in FIG. 15, the incident surface of the light guide body 17 has an upper end portion with respect to the central portion 171c in the cross section of the plane parallel to the incident light and the emitted light to the light guide body. The curvatures of 171a and the lower end 171b are made large. This is effective when the LED element 14 having a relatively large size of the light emitting portion is used as shown in FIG. That is, the light emitted from the central portion of the LED element 14 is converted into parallel light by the LED collimator 15 like the light rays L30c, L30a, L30b shown by the solid line, but the light emitted from the upper end and the lower end of the LED element 14. Is not parallel light but diffused light like the light rays L30d and L30e shown by the one-point chain line. Therefore, in order to convert the light into parallel light, the incident surface of the light guide body 17 is set to the upper end portion 171a and the lower end portion. As shown in 171b, it is necessary to increase the curvature with respect to the central portion 171c. By adopting the above configuration, it is possible to realize a light source device having good characteristics even when an LED having a relatively large size is used.

[1-14: Method for manufacturing a light guide body]
Further, as described above, the angle β1 = β2 = β3 = β4 …… βn ≧ 90 °, which is for manufacturing the light guide body 17 by injection molding as shown in FIG. This is because, in the processing of the mold 178, the reflecting surface 178a corresponding to the reflecting surface 172b and the connecting surface 178b corresponding to the connecting surface 172b can be simultaneously processed by the end mill having a relative angle β between the bottom surface and the side surface. Further, since the reflective surface 178a and the connecting surface 178b can be machined with a relatively thick tool, the machining time can be significantly shortened and the machining cost can be significantly reduced. Further, the boundary edge between the reflecting surface 178a and the connecting surface 178b can be processed with high accuracy, and the light guide characteristics of the light guide body 17 can be improved.

[1-15: Video Display Device (Other Examples)]
FIG. 19 is an overall external perspective view of the image display device 30 showing another example of the image display device 30 to which the above-mentioned light source device is applied. In this embodiment, although details are not shown, the heat generated in the LED substrate 12 is cooled by the heat sink 13c arranged at the lower part of the device through the heat transfer plate 13d. According to this configuration, a light source device having a short overall length is realized.

[1-16: Light Source Device (Other Examples)]
Further, further examples of the light source device according to the above-described embodiment of the present invention are shown below. FIG. 20 shows a light source device for a larger liquid crystal display device in which the arrangement of the LED elements 14 which are solid light sources is 3 × 2 rows as compared with the above-described embodiment. In the light source device according to this embodiment, when the light guide body 17 is manufactured by injection molding, the incident portion 171 becomes thicker, so that the cooling time in the molding mold increases, the molding tact becomes longer, and the cost increases. In order to prevent this from happening, a part of the incident portion 171 (upper part of the drawing) is deleted.

Further, FIG. 21 shows a larger light source device for a liquid crystal display device in which the arrangement of the LED elements 14 which are solid light sources is 3 × 2 rows, similar to the light source device of the above embodiment. In this example, by deleting a part of the incident portion 171 and thickening the tip portion (right side portion in the drawing) of the light guide body 17, the cooling rate at the time of molding is made uniform, so that the accuracy is higher. It enables various molding. In this example, the light guide body 17 is configured so that the main light ray is incident at an angle of incidence on the liquid crystal display panel by a predetermined angle η by thickening the tip portion thereof. This is because, in general, it is desirable that the inclination of the main light beam incident on the liquid crystal display panel is close to vertical. However, some commercially available liquid crystal display panels have better characteristics when the incident angle is tilted by about 5 to 15 ° depending on the characteristics, and the incident light to the liquid crystal display panel according to the characteristics. Is tilted by an angle η = 5 ° to 15 ° to enter.

[1-17: Texture of light guide body]
Further, FIG. 22 is a top view showing a specific example of the above-mentioned texture formed on the reflective surface of the light guide body 17 also shown in FIG. 15. In this schematic diagram, an example in which the boundary between the reflecting surface and the connecting surface is linearly arranged and formed is shown in FIG. 22 (a), and in FIG. 22 (b), for example, an LED element which is a light source. Other examples are shown in which 14 (14a, 14b) are arranged and formed in a curved line according to the necessity, such as being arranged so as to be separated from each other and dispersed.

[1-18: Video Display Device (Other Examples)]
The above shows an example of a light source device according to an embodiment of the present invention, in particular, an example of a light source device applied to the HUD device 1, but the following shows an example including further configurations of the light source device. ..

In FIG. 23, a plurality of light source devices (two in this example) including the above-mentioned LED elements 14 (14a, 14b), a light guide body 17, and the like are combined so that their emission portions 173 are in the same plane. , An example corresponding to a larger liquid crystal display panel 52 is shown. In addition, according to such a combination structure, it is possible to further realize a video display device provided with more types of surface sizes and light emission emitting units 173.

[1-19: Video Display Device (Other Examples)]
FIG. 24 further shows a light source device composed of a light guide body 17'with a plurality of (two in this example) incident portions 171A and 171B, and as is clear from the drawings, the light guide. On both side surfaces of the body 17', incident portions 171A and 171B that incident light from a light source composed of LED elements 14 (14a and 14b), an LED collimator 15 and the like are formed, and the incident portions 171A and 171B are formed. The parallel light incident from the light source is refracted and guided to the reflecting portion 172 formed at the bottom of the light guide body 17'in this example. The surface of the reflective portion 172 is formed with irregularities having a wavy cross section, and a reflective film (aluminum film) that reflects light is further formed. According to this, the parallel light incident from the incident portions 171A and 171B is reflected by the reflecting portion 172 as shown by an arrow in the drawing and directed toward the upper side of the light guide body 17'. It is emitted toward a device such as a liquid crystal display panel 52.

According to the light source device having such a configuration, even if the size of the liquid crystal display device that irradiates light is increased, it is possible to relatively easily cope with it, that is, to realize a light source device having an enlarged emission surface. As is clear from the above, since the light source device can be realized by the relatively thin light guide body 17', the device can be made thinner. Further, the thickness of the light guide body 17'is almost uniform, and its formability is good.

Further, a light guide body that reflects and refracts the light incident from the incident portions 171A and 171B inside the incident portion and emits the light from the emitting portion 173 to an external device (in this example, the liquid crystal display panel 52 which is an optical device in the subsequent stage). In 17', the area SIN of the light incident surface is generally set to be larger than the area SOUT of the light emitting surface (SIN> SOUT), and the shape of the light guide body 17'is an LED element which is a light emitting element. It will be possible to form a shape suitable for the size and shape of 14.

[1-20: Light Source Device (Other Examples)]
Further, as shown in FIG. 25, it is also possible to configure the light guide body 17 "arranged behind the synthetic diffusion block 16 by the polarization conversion element 21'. In this configuration, it is clear from the drawings. As described above, the translucent member 211'of the triangular column constituting the polarization conversion element 21'and the translucent member 212' of the parallel quadrilateral column are combined. The LED element 14 (14a, 14a, The S-polarized wave of the incident light emitted from 14b) and turned into parallel light by the LED collimator 15 (see the symbol (x) in the figure) is reflected, while the P-polarized light (see the upper and lower arrows in the figure). ) Is formed. Along with this, a 1 / 2λ phase plate 213 is formed on the upper surface of the translucent member 212'of the parallel quadrilateral column, and a reflective film 212 is formed on the side surface thereof. Each is formed.

According to the above-described configuration, as is clear from the drawings, the incident light emitted from the LED element 14 and turned into parallel light by the LED collimator 15 works as a polarization conversion element 21'constituting the light guide body 17 ". It is polarized to S polarization and emitted upward from the upper surface of the element. That is, in the above configuration, in particular, the light guide body 17 "is configured by the polarization conversion element 21'to be an apparatus. It is possible to realize a significant reduction in the size of the LED and a significant reduction in the manufacturing cost of the device.

(Embodiment 2)
A light source device and the like according to another embodiment of the present invention (referred to as a second embodiment) will be described with reference to FIGS. 26 to 51. The light source device of the second embodiment has a unique light guide structure, and includes the following components. The light source device of the second embodiment has an arrangement configuration including a unique light guide body different from that of the first embodiment (FIG. 30 described later). This light guide has a free curved surface shape on at least one of an incident surface and an emitted surface. The free curved surface shape realizes the characteristics of predetermined light distribution control in the light guide body. Further, the liquid crystal display element 50 and the refraction element 43 have a predetermined angle so as to be oblique to the optical axis of the light emitted from the light guide. The characteristics of the orientation control of the light guide are composed of the arrangement angle of the incident surface, the refraction angle depending on the surface shape, the reflection angle of the reflection surface, the arrangement angle of the emission surface, the refraction angle due to the free curved surface shape, and the like. .. The light distribution control characteristic of the light source device of the second embodiment is composed of a combination of the light distribution control characteristic of the light guide body and the light distribution control characteristic of the light source unit and other optical elements of the illumination optical system. The light source.

[2-1: HUD device]
FIG. 26 shows the vicinity of the driver's seat of the vehicle 2 equipped with the HUD device 1 from the side as a conceptual configuration of the in-vehicle HUD device 1 configured by using the image display device 30 including the light source device 10 of the second embodiment. The schematic configuration seen is shown. A real image (for example, a landscape such as a road) transmitted from the driver's eyes 5 (also referred to as a viewpoint) sitting in the driver's seat through the display area 4 of the windshield 3 in front, or superimposed on the real image by the HUD device 1. It shows how to see the displayed virtual image 7 (for example, an arrow image). In FIG. 26, the X direction, the Y direction, and the Z direction are shown as explanatory directions. The X direction (direction perpendicular to the drawing) corresponds to the first horizontal direction, the left-right direction of the vehicle 2, and the lateral direction of the display area 4. The Y direction (horizontal direction in the drawing) corresponds to the second horizontal direction, the front-rear direction of the vehicle 2, and the front-rear direction of the display area 4. The Z direction (vertical direction in the drawing) corresponds to the vertical direction, the vertical direction of the vehicle 2, and the vertical direction of the display area 4.

The windshield 3 is made of glass or the like and has a light-transmitting visible region. The visible area is an area where the image can be visually recognized from the driver's point of view. The display area 4 of the HUD device 1 is configured in the visible area of the windshield 3. The display area 4 is an area on which the image light is projected by the HUD device 1, and corresponds to a range in which the virtual image 7 can be displayed.

The HUD device 1 is mounted on the vehicle 2 and is provided, for example, as a part of an in-vehicle system. The HUD device 1 is installed, for example, in a part of the dashboard of the vehicle 2. The HUD device 1 includes a video display device 30 and an optical system. In the HUD device 1, components of the image display device 30 and components of an optical system are arranged and housed in an outer case which is a housing. A part of the housing, for example a part of the upper surface, has an opening. The opening is covered with an antiglare plate (glare trap) or the like. The optical system components include reflection mirrors 41 and 42, a refraction element 43, and the like, which will be described later.

The image display device 30 includes a light source device (light source module) 10 and a liquid crystal display element 50 which is a display element. The video display device 30 is a projector that generates and emits video light based on video data to display a projection on a windshield 3 (or a combiner or the like (not shown)). The combiner is a dedicated display board provided immediately before the windshield 3. The light source device 10 includes an LED element and an illumination optical system as shown in the first embodiment described above, and generates and irradiates the illumination light for the liquid crystal display element 50.

The liquid crystal display element 50 generates image light based on the display signal and the illumination light from the light source device 10, and emits the image light to an optical system (particularly referred to as an adjustment optical system). The adjusting optical system includes a refracting element 43 and reflection mirrors 42 and 41 as optical components. These optical components realize a function (display distance adjustment mechanism) for adjusting the projection position, display distance, and the like of video light with respect to the windshield 3. The HUD device 1 reflects and enlarges the image light emitted from the liquid crystal display element 50 of the image display device 30 by the reflection mirror 41 and the reflection mirror 42 via an optical element such as a refraction element 43, and windshield 3 Project to a part of the area.

The refracting element 43 is composed of a lens or the like that refracts image light. A drive unit such as a motor for changing the arrangement angle or the like may be connected to the refraction element 43 so that the optical axis and the direction of refraction can be adjusted. The reflection mirror 42 is, for example, a plane mirror, and the light emitted from the liquid crystal display element 50, for example, substantially in the vertical direction (Z direction) is directed toward the reflection mirror 41 substantially forward (left in the Y direction). Reflect to. The reflection mirror 41 is, for example, a concave mirror, and reflects the image light substantially incident from the Y direction toward the windshield 3 which is substantially above the vertical direction (Z direction). A drive unit such as a motor for adjusting the arrangement angle or the like may be connected to the reflection mirrors 41 and 42 so that the direction of the optical axis can be adjusted.

The image light emitted from the HUD device 1 (reflection mirror 42) is substantially reflected to the right in the Y direction by the surface of a part of the windshield 3 (display area 4), and is incident on the driver's eyes 5. And image on the retina. As a result, the driver sees the image light and visually recognizes the image or image superimposed on the transmitted real image as a virtual image 7 in the display area 4 of the windshield 3 in front of the field of view.

The optical axis of the image light and the line-of-sight 6 when the virtual image 7 is viewed from the driver's eyes 5 are shown by a alternate long and short dash line. Further, the optical axis of external light such as sunlight incident on the windshield 3 and the inside of the HUD device 1 from the outside of the vehicle 2, for example, from above is indicated by a two-dot chain line.

[2-2: HUD device-functional block]
FIG. 27 shows the internal functional block configuration of the HUD device 1 of FIG. The HUD device 1 includes a control unit 1A, an image display device 30, and an adjustment optical system 40. The image display device 30 includes a display control unit 30A, a light source device 10, and a liquid crystal display element 50 which is a display element. The liquid crystal display element 50 is a transmissive or reflective liquid crystal display device.

The light source device 10 includes the light source unit 301 and the illumination optical system 302 as described above. The light source unit 301 is composed of the LED element 14 and the like as shown in the first embodiment described above. As shown in the first embodiment, the illumination optical system 302 includes an LED collimator 15, a polarization conversion element 21, a light guide body 17, and the like. As described above, the polarization conversion element 21 is composed of a translucent member (prism), a PBS film, a phase plate, and the like. The adjusting optical system 40 includes a refracting element 43, reflection mirrors 42, 41 and the like. At least the reflection mirror 43 is connected to a drive unit 44 for variably adjusting the arrangement angle.

When the HUD device 1 is connected to an in-vehicle system, the HUD device 1 can operate according to control from an engine control unit (ECU) or the like (not shown). The control unit 1A of the HUD device 1 controls the display of the virtual image 7 in the display area 4 by controlling the display control unit 30A of the image display device 30, the drive unit 44 of the adjustment optical system 40, and the like. The display control unit 31 generates video data for displaying the virtual image 7 according to the control from the control unit 1A, and gives a drive control signal and a display signal to the light source device 10 and the liquid crystal display element 50. The light source device 10 generates and emits illumination light by controlling on / off of light emission of the LED element 14 according to a drive control signal. The light generated from the light source unit 301 is condensed and uniformized by the illumination optical system 302, and is applied to the surface of the liquid crystal display element 50 as planar illumination light. The liquid crystal display element 50 includes a display drive circuit, and generates and emits image light according to a display signal and illumination light. In the illumination optical system 302, the orientation control of predetermined characteristics for generating illumination light suitable for the liquid crystal display element 50 and the HUD device 1 is performed by the optical component.

The display element is not limited to the liquid crystal display element 50, and other types of elements can also be applied. In that case, characteristics including light distribution control of the adjusting optical system 40 and the light source device 10 are implemented so as to match the characteristics of the display element.

[2-3: Comparative examples, problems, etc.]
FIG. 28 shows a schematic configuration of the HUD device 280 of the comparative example with respect to the second embodiment, and an explanatory diagram regarding a problem of the influence of external light and the like. The outline of the component arrangement of the HUD device 280 of FIG. 28 is the same as that of FIG. 26. The HUD device 280 of the comparative example has the same components as those of the above-mentioned embodiment. The light source device 10 includes a heat sink 13, an LED substrate 12, an LED element 14, an LED collimator 15, a polarization conversion element 21, a synthetic diffusion block 16, and diffusion in this order from front (left in the drawing) to rear (right in the drawing) in the Y direction. The plate 18a and the light guide body 17 are arranged. The light emitting axis of the LED element 14 is in the Y direction, and is indicated by the optical axis a1. The light guide body 17 has a columnar cross section having a triangular cross section. A diffusion plate 18b, a liquid crystal display element 50, a refraction element 43, and a reflection mirror 42 are arranged in this order from the light guide body 17 in the Z direction. The reflection mirror 41 is arranged in front (left) in the Y direction from the reflection mirror 42. The opening 81 of the housing 80 is located above the reflection mirror 41 in the Z direction.

The light axis extending in the Y direction from the light emitting point of the LED element 14 is indicated by the optical axis a1. The optical axis a1 is converted into the optical axis a2 in the Z direction by the reflecting portion of the light guide body 17. The entrance surface and the exit surface of the light guide body 17 are flat surfaces. The emission surface of the light guide body 17 and the diffuser plate 18b are arranged on a horizontal XY plane. In the Z direction, the panel surface of the liquid crystal display element 50 is arranged above the emission surface of the light guide body 17 and the diffusion plate 18b in a state of being tilted to some extent on a horizontal XY plane. On the optical axis a2, the refraction element 43 is similarly tilted above the liquid crystal display element 50.

On the optical axis a2, the image light emitted from the liquid crystal display element 50 passes through the refraction element 43 and is incident on the point Q2 of the reflection mirror 42. The optical axis a2 becomes the optical axis a3 substantially to the left in the Y direction due to reflection at the point Q2 of the reflection mirror 42. The optical axis a3 is incident on the point Q1 of the reflection mirror 41. The optical axis a3 becomes the optical axis a4 substantially upward in the Z direction by reflection at the point Q1 of the reflection mirror 41. The optical axis a4 is incident on and reflected at the point Q3 in the display region 4 of the windshield 3, becomes an optical axis a5 substantially to the right in the Y direction, and is incident on the driver's eyes 5.

The angle of the reflection mirror 41 is indicated by an angle θ1. This angle θ1 corresponds to, for example, a rotation angle centered on the rotation axis in the X direction (in this example, an angle with the horizontal plane as a reference of 0 degrees), and can be changed through the drive unit 44.

When it is desired to reduce the size of the HUD device 280 in the height direction (Z direction), the optical axis is bent in the Y direction and the Z direction by using the light guide body 17 as in this comparative example, and in the Y direction. Parts such as a heat sink 13, an LED substrate 12, an LED collimator 15, and a polarization conversion element 21 are arranged. As a result, the size in the Z direction can be kept small, but the size in the Y direction becomes relatively large. In particular, when a plurality of LED elements 14 are used to increase the amount of light, or when a large heat sink 13 or the like is used to increase heat dissipation performance, the size in the Y direction increases. This is disadvantageous for downsizing the HUD device 1.

Since the HUD device is installed in a limited space such as a dashboard in a vehicle, a smaller and more efficient device is required. It is desirable that the image display device 30 and the light source device 10 be realized as a smaller and more efficient module so as to be suitable for mounting a HUD device or the like. Further, it is required to generate suitable image light for a virtual image while downsizing the HUD device. Suitable illumination light from the light source device 10 is required for the generation of suitable video light. Further, the cooling performance of the light source unit is also required. The light source device 10 needs to generate suitable planar illumination light that matches the characteristics of the HUD device 280, the liquid crystal display element 50, and the like. The illumination light is required to have, for example, a predetermined amount of light, a surface size, a uniform distribution of light intensity in the surface, and the like. While ensuring these characteristics, miniaturization of the device is also required.

The image light from the image display device 30 is subjected to actions such as refraction, reflection, and enlargement via the adjustment optical system 40, and is projected onto the display area 4 of the windshield 3, and is projected by the driver's eyes at a predetermined convergence angle. It is incident on 5. From the driver's point of view, the virtual image 7 corresponding to the predetermined convergence angle is observed through the display area 4. The predetermined convergence angle varies depending on the HUD optical system, but is generally about 4 ° to 10 ° in the horizontal direction (horizontal light) and about 1.5 ° to 5 ° in the vertical direction (vertical light) with respect to the driver. There is. In order to obtain a predetermined convergence angle suitable for the image light of the HUD, it is necessary to sufficiently magnify the image light before it is incident on the reflection mirror 41. In particular, in order to realize a convergence angle of horizontal light from 4 ° to 10 °, it is necessary to expand the image light to 200 mm or more. For that purpose, it is necessary to take measures such as expanding the emitted light by the light source device 10 and expanding the emitted light by the refracting element 43 and the reflecting mirror 42 of the adjusting optical system 40.

Further, in the configuration including the optical system of the comparative example of FIG. 28, the optical axis a2 in the Z direction of the light emitted from the light source device 10 (light guide body 17) and the axes (normal lines) of the liquid crystal display element 50 and the refraction element 43. Direction) is arranged at a predetermined angle. In such a configuration, there is also a problem of the influence of external light as follows. In FIG. 28, the optical path when the external light enters the HUD device 280 is shown by the optical axes b1 to b4 of the alternate long and short dash line. The optical axes b1 to b4 travel in the opposite direction to the optical path (optical axes a1 to a5) at which the image light is emitted. Since the optical axis b2 and the like overlap with the optical axis a4 and the like, they are shown with a slight shift.

When external light is incident on the HUD device 280, the external light is incident on the refraction element 43 and the liquid crystal display element 50 through the reflection mirrors 41 and 42 of the adjustment optical system 40. Further, the external light is reflected by the refraction element 43 or the like, returns to the optical path in the opposite direction, and a part of the external light goes out of the HUD device 280. Then, the external light may be reflected by the windshield 3 and incident on the driver's eyes 5. As a result, the driver visually recognizes the virtual image 7 in a state where the external light is reflected as noise in the video light of the virtual image 7 in the display area 4. Therefore, it may be difficult for the driver to visually recognize the virtual image 7. That is, the display quality of the virtual image is deteriorated.

First, the optical axis b1 of the external light from above the vehicle 2 is incident on the point Q3 of the display region 4 of the windshield 3. A part of the outside light is reflected by the surface of the windshield 3. The optical axis b2 of the external light incident on the windshield 3 is incident on the point Q1 of the reflection mirror 41 via the opening 81. The optical axis b3 of the external light reflected at the point Q1 is incident on the point Q2 of the reflection mirror 42. The optical axis b4 of the external light reflected at the point Q2 is incident on the refraction element 43 and the liquid crystal display element 50. The external light reflected by the refracting element 43 or the like returns in the direction opposite to that at the time of incident, as in the optical axes b5, b6, and b7. The external light goes out from the inside of the HUD device 280, is reflected at the point Q3 of the display area 4 of the windshield 3, and is incident on the driver's eye 5 like the optical axis b8.

In the light source device 10 and the adjustment optical system 40 of the HUD device 280, a light distribution control that realizes a predetermined convergence angle is required for suitable image light for forming a virtual image 7 of a suitable display area 4. For the light distribution control, for example, the configuration shown in FIG. 28 is adopted. In this configuration, as described above, an external light component (sometimes referred to as return external light) that returns to the outside of the HUD device 280 is generated due to reflection of external light incident on the HUD device 280 or the like. That is, the incident external light is eliminated by reflection or absorption to some extent by the function of the windshield 3 or the opening 81 of the HUD device 1 by tilting the refraction element 43 or the liquid crystal display element 50 to some extent, but particularly refraction. Since the surface of the element 43 is concave, a part of the reflected light reverses the incident optical path and cannot be completely excluded. Therefore, when the return external light is incident on the driver's eyes 5, the display quality of the virtual image 7 is deteriorated.

Therefore, the light source device or the like of the second embodiment provides a function capable of preventing or reducing the influence of external light as described above in order to improve the display quality of the HUD. In the light source device and the like of the second embodiment, the direction of the optical axis with respect to the liquid crystal display element 50, the refraction element 43, and the like is different from the configuration of the comparative example by devising the structure of the light source unit 301 and the illumination optical system 302 (described later). (Fig. 29, etc.). According to the study, it is effective to set the normal inclination angle of the effective surface (the surface through which the image light is transmitted or reflected) of the refracting element 43 or the like to at least 10 ° with respect to the optical axis of the illumination light and the image light. It turned out to be. By this ingenuity, in the light source device or the like of the second embodiment, a predetermined light distribution control characteristic is realized so as to satisfy both the generation of suitable image light and the prevention of return external light. The illumination light generated based on the predetermined light distribution control in the light source device is supplied to the liquid crystal display element. Then, video light having predetermined suitable characteristics for the display area of the HUD device is generated and emitted. The image light is projected onto the display area of the windshield via the adjusting optical system including the refracting element 43 and the like. Here, since the predetermined light distribution control is performed by the light source device as described above, the distribution of the refraction angle in the refraction element 43 does not need to be as wide as in the comparative example. That is, the surface shape of the refracting element 43 does not need to have a concave inclination (curvature) as tight as in the comparative example. As a result, in the light source device or the like of the second embodiment, when the external light is incident on the HUD device, the refraction element 43 or the liquid crystal display element 50 is tilted to some extent so that the external light is adjusted by the adjusting optical system or the liquid crystal display element. Even if it is reflected by the HUD device, it hardly returns to the outside of the HUD device, that is, almost no return external light is generated. Therefore, it is possible to prevent or reduce the deterioration of the display quality of the virtual image due to the return external light incident on the driver's eyes. That is, in the second embodiment, it is possible to obtain the effect of preventing or reducing the return external light and suppressing the deterioration of the visibility of the virtual image due to the influence of the external light while ensuring suitable image light.

In the comparative example, in order to reduce the influence of external light, an optical element or the like is installed in the adjustment optical system 40 in the HUD device 280 so as to divert the external light and not reflect it to the display region 4 (for example, FIG. 28). When the liquid crystal display element 50 and the refraction element 43 are arranged at an angle with respect to the horizontal plane), the characteristics of the image light are inevitably affected. Therefore, the light distribution control characteristics of the light source device 10, the liquid crystal display element 50, the refraction element 43, etc. are devised and controlled so as to secure predetermined suitable characteristics of the image light while reducing the influence of the return external light. There is a need to.

By adopting the configuration in which the normal tilt angle is provided in the second embodiment, the light reflected by the refracting element 43 or the like in the external light incident in the reverse direction of the optical path of the video light has at least the above-mentioned normal tilt with respect to the incident light. The direction shifts with, for example, 20 °, which is twice the angle (for example, 10 °). Therefore, it is possible to prevent or reduce the reflected light that goes out from the HUD device 1 (opening 81), returns, is reflected by the windshield 3 again as external light, and is incident on the driver's eyes 5. However, in order to satisfy such a condition for avoiding external light, the structure of the adjusting optical system 40 such as the refracting element 43 and the reflecting mirrors 41 and 42 is naturally limited.

Due to the above limitations, suitable image light (light sufficiently magnified for the display region 4) cannot be realized only by the measures for enlarging the light by the adjustment optical system 40 such as the refraction element 43 described above. Therefore, in order to realize a suitable image light, it is necessary to devise a combination of a configuration in which the emission light is expanded by the adjusting optical system 40 and a configuration in which the illumination light is expanded by the light source device 10. As a result of various studies, as a configuration that can simultaneously realize miniaturization, thinning, and high efficiency of the light source device and expansion control of the illumination light, at least one of the entrance surface and the emission surface of the light guide has a free curved shape. It was found that the configuration that controls the orientation is effective.

[2-4: HUD device-light distribution control]
FIG. 29 shows a schematic configuration, orientation control, and the like of the HUD device 1 including the light source device 10 and the image display device 30 of the second embodiment with respect to the comparative example of FIG. 28. An optical path or the like when external light is incident on the HUD device 1 is also shown. The light source device 10 and the image display device 30 of the second embodiment have different light distribution control characteristics from those of the comparative example. Note that FIG. 29 and the like are schematic configurations, and the size and the like of the mounting are not limited to those of FIG. 29 and the like.

In FIG. 29, the light source unit 301 includes an LED substrate 12 on which a plurality of LED elements 14 and control circuits are mounted. A heat sink 13 is provided on the back side of the LED substrate 12. The illumination optical system 302 includes an LED collimator 15 arranged in the Y direction, a polarization conversion element 21, a light guide body 17, a diffuser plate 18b arranged in the Z direction, and the like. The LED collimator 15 collects the light from the LED element 14 on the optical axis a1 in the Y direction and converts it into parallel light. The polarization conversion element 21 performs optical conversion on the incident light from the LED collimator 15 so as to polarize the light flux direction and widen the light flux width, and then emits the light. The light guide body 17 guides the light axis 17 so as to convert the direction of the optical axis a1 in the Y direction from the LED element 14 into the direction of the optical axis a2 in the Z direction that irradiates the liquid crystal display element 50. In the second embodiment, the light guide body 17 has a columnar shape having a substantially trapezoidal cross section, and the direction of light is substantially converted from the Y direction (horizontal direction) to the Z direction (vertical direction). Specifically, the light emitted from the light guide body 17 is an optical axis tilted at a predetermined angle with respect to the Z direction through the free curved surface shape of the light emitting surface (slope having a predetermined angle with respect to the horizontal plane) of the light guide body 17. It becomes.

The optical axis of the illumination light and the image light and the axis (normal inclination angle) of the liquid crystal display element 50 and the refraction element 43 have a predetermined angle (for example, 10 °) as described above. Illumination light, which is light emitted from the light guide body 17, enters the liquid crystal display element 50 arranged at a predetermined angle on a horizontal plane (XY plane), and image light is generated. The image light from the liquid crystal display element 50 has an optical axis tilted at a predetermined angle with respect to the Z direction. The image light is incident on the refracting element 43 arranged at a predetermined angle on the horizontal plane (XY plane). The image light is refracted through the refracting element 43, and then is incident on the point Q2 of the reflection mirror 42 and reflected. The light on the optical axis a3 after reflection is incident on the point Q1 of the reflection mirror 41 and reflected. The optical axis a4 of the reflected light is incident on and reflected at the point Q3 of the display region 4 of the windshield 3 via the opening 81. The optical axis a5 of the reflected light is incident on the driver's eyes 5.

For example, a drive unit 44 for changing the angle of the reflection mirror 42 is connected to the adjustment optical system 40. The drive unit 44 changes the angle θ1 (having a predetermined correspondence with the optical axis direction) of the reflection mirror 41 by driving a motor or the like. The drive unit 44 changes the angle θ1 of the reflection mirror 41 based on the control from the control unit 1A of the HUD device 1 or the manual input operation of the driver. By changing the angle θ1 of the reflection mirror 41, the projection direction (optical axis a4) of the image light from the HUD device 1 is changed. As a result, the projection position of the image light on the windshield 3 is changed, and the position of the display area 4 is changed. Therefore, the position of the display area 4 in the windshield 3 can be adjusted so as to move up and down in the Z direction, for example, when viewed from the driver. The position of the display area 4 can be suitably adjusted according to the position of the driver's eyes 5 and the like.

In the light source device 10 of the second embodiment, the LED substrate 12, the LED collimator 15, the polarization conversion element 21, and the like are devised to secure the light utilization efficiency, reduce the size of the device, and reduce the size in the Y direction. In the light source device 10 and the adjusting optical system 40 of the HUD device 1 of the second embodiment, light distribution control that realizes a predetermined convergence angle is required in order to generate suitable video light. Further, in the HUD device 1 of the second embodiment, a predetermined light distribution control for the return external light prevention function is also required. In order to realize the light distribution control that satisfies both of them, the HUD device 1 of the second embodiment has a configuration as shown in FIG. 29 including a unique light guide body 17. In this configuration, the optical axis (normal tilt angle) of the optical element such as the refraction element 43 is at a predetermined angle (normal line tilt angle) with respect to the optical axis of the illumination light from the light source device 10 and the image light from the liquid crystal display element 50. It is different so that it has (10 ° or more) (see the angle φ2 and the like in FIG. 30 described later).

In FIG. 29, the optical path when external light enters the HUD device 1 is as follows. Similar to the comparative example, the optical axes b1 to b4 when the external light is incident are shown. The optical axis b4 indicates light reflected by the point Q2 of the reflection mirror 42 and incident on the refracting element 43 or the like. The optical axis b4 is different from the axis (normal tilt angle) of the refraction element 43 and the liquid crystal display element 50 with an angle. Therefore, the light reflected by the refraction element 43 and the liquid crystal display element 50 from the optical axis b4 travels in a direction different from that of the above-mentioned optical axis b5. Since the reflected external light hits the housing 80 and is attenuated or the like, it is prevented or reduced from going out through the opening 81. This prevents or reduces the incident of return external light on the driver's eyes 5.

[2-5: HUD device-light distribution control (2)]
FIG. 30 shows an outline of the configuration of the light source device 10, the image display device 30, the adjusting optical system 40, and the like according to the second embodiment. FIG. 30 shows a more detailed configuration example than that of FIG. 29. In FIG. 30, the light source device 10 includes a heat sink 13, an LED substrate 12 (LED element 14), an LED collimator 15, a polarization conversion element 21, a light distribution control plate 16b, and a light guide 17 in this order from left to right in the Y direction. Have been placed. A plurality of LED elements 14 are arranged in the X direction of the LED substrate 14 (FIG. 32, etc. described later). The light emitting surface of the LED element 14 is arranged so as to come out in contact with the top surface of the recess of the LED collimator 15 (FIG. 33, etc. described later). A plurality of collimator elements 15A are arranged in association with the positions of the plurality of LED elements 14 in the X direction of the LED collimator 15. In the polarization conversion element 21, the extending direction of the member such as the PBS film is the X direction, and the arrangement direction of the plurality of members is the Z direction (FIG. 35, etc. described later). A plurality of members are arranged at positions and shapes that are vertically symmetrical in the Z direction with respect to the optical axis a1 in the Y direction from the LED element 14. An incident portion 171 (incident surface s1) of the light guide body 17 is arranged on the emission side of the light distribution control plate 16b.

As a result, when a plurality of parts such as LED elements 14 are arranged in parallel in the X direction, a plurality of parts can be compactly arranged in the X direction, the size of the device in the X direction can be reduced, and the size can be reduced. Can contribute. Alternatively, more components can be placed within a predetermined size in the X direction of the device, for example, a larger amount of light can be secured by arranging a large number of LED elements 14. Further, since the degree of freedom in arranging the parts in the X direction is increased, it becomes easy to support various mountings of the HUD device 1. For example, mounting according to the size of various display areas 4 becomes easy.

The light guide body 17 has a substantially trapezoidal shape in the illustrated YY cross section. The light guide body 17 includes an incident portion 171 (including the incident surface s1), a reflecting portion 172 (including the reflecting surface s2), an emitting portion 173 (including the emitting surface s3), and a parietal portion 175 (including the parietal surface s5). Have. In this example, the incident surface s1 of the incident portion 171 is arranged at a predetermined angle with respect to the vertical Z direction, but may be a plane in the Z direction. The reflection surface s2 of the reflection unit 172 has a structure in which a plurality of reflection surfaces and connecting surfaces are alternately repeated, as in the first embodiment. On the opposite side of the incident surface s1 in the Y direction, there is a parietal surface s5. By providing the crown portion 175, the exit surface s3 of the emission portion 173 is basically configured as a slope having a predetermined angle φ1 with respect to the horizontal Y direction. Further, the exit surface s3 has a free curved surface shape. This free curved surface shape is a shape for realizing a predetermined light distribution control. The shape of the free curved surface of the exit surface s3 is shown as a convex shape, but the present invention is not limited to this, and details will be described later.

The refraction element 43 is composed of an optical element such as a lens having a predetermined refractive index, and has a concave shape on the incident side and the exit side as shown in FIG. 30 as a detailed shape. The inclination of the concave surface of the refracting element 43 is gentler than the inclination of the concave surface of the refracting element 43 of the comparative example. In other words, the difference in height (curvature) between the center and the periphery of the concave surface is relatively small. Not limited to this, the refracting element 43 may have a concave surface on the incident side and a convex surface on the exit side as shown in FIG.

The optical path of the image light is as follows. Generally, the optical axis a1 in the Y direction from the LED element 14 becomes the optical axis a2 in the Z direction through reflection by the light guide body 17. The optical axis a2 of the light emitted from the light guide 17 is converted into a direction (optical axes a22, a23) having a predetermined angle φ3 with respect to the Z direction through the action of the emission surface s3. The axes of the liquid crystal display element 50 and the refraction element 43 form a predetermined angle φ2 with respect to the optical axis. In this example, the panel surface of the liquid crystal display element 50 and the refraction element 43 are arranged at a predetermined angle (angle φ5 in FIG. 42 described later) with respect to the XY plane. As described above, the optical axes a23, a24, and a25 are non-orthogonal with respect to the axes of the liquid crystal display element 50 and the refraction element 43, and have an angle φ2.

The light emitting point of the LED element 14 is indicated by point p1. The optical axis a1 in the Y direction from the point p1 is shown. The point p2 through which the optical axis a1 passes on the incident surface s1 of the light guide body 17 is shown. The point p3 where the optical axis a1 hits on the reflection surface s2 of the light guide body 17 is shown. By being reflected at the point p3, it is converted from the optical axis a1 to the optical axis a21 in the Z direction. The point p4 through which the optical axis a21 passes on the exit surface s3 is shown. The optical axis a22 after refraction is shown through the point p4 of the emission surface s3. The optical axis a22 is incident on the point p5 of the liquid crystal display element 50 via the diffuser plate 18b. The optical axis a23 of the image light from the point p5 of the liquid crystal display element 50 is shown. The optical axis a22 and the optical axis a23 have an angle φ3 with respect to the Z direction. The video light of the optical axis a23 is incident on the point p6 of the refraction element 43 and is subjected to the action of refraction to become the optical axis a24. The optical axis a24 has a predetermined angle φ3 with respect to the Z direction, and has a predetermined angle φ2 with respect to the axes of the liquid crystal display element 50 and the refraction element 43. The video light of the optical axis a24 is incident on the point Q2 of the reflection mirror 42 and reflected, and becomes the above-mentioned optical axis a3.

Further, when the above-mentioned external light is incident on the HUD device 1, the optical axis b3 of the external light from the reflection mirror 41 is reflected by the point Q2 of the reflection mirror 42 and is reflected by the optical axis b4 (in the opposite direction of the optical axis a24). It becomes. The external light of the optical axis b4 is incident on the point p6 of the refracting element 43. In the second embodiment, the optical axis has an angle of φ2, so that the return external light is unlikely to be generated. Of the external light of the optical axis b4, the external light reflected by the refracting element 43 travels in a direction different from that of the comparative example. The light beam of the reflected external light corresponding to the outermost part of the range corresponding to the display region 4 in the external light of the optical axis b4 is shown by the light beam b9. The light ray b9 is displaced with respect to the optical axis b4 at an angle corresponding to twice the angle φ2. The light ray b9 of the reflected external light hits the housing 80 or the like and is attenuated, so that it is difficult for the light beam b9 to return to the outside through the opening 81. Similarly, among the external light of the optical axis b4, the light beam of the reflected external light when it passes through the refraction element 43 and is incident on the liquid crystal display element 50 is shown by the light ray b10. Similarly, the light ray b10 travels on an optical axis different from that of the image light, and is difficult to return to the outside from the opening 81 due to attenuation or the like. There is almost no return external light component on the optical axis a5 of the line of sight 6. In this way, the return external light is prevented and reduced from entering the driver's eyes 5. As a result, when the driver sees the virtual image 7 through the point Q3 in the display area 4 with the line of sight 6, the virtual image 7 can be preferably visually recognized.

As described above, according to the second embodiment, it is possible to reduce the size of the device, secure the suitable image light of the HUD, prevent or reduce the return external light, and suppress the deterioration of the quality of the virtual image 7 due to the external light. The configuration is not limited to the optical axis shown in FIG. 30, and any configuration may be used as long as the incident surface s1 or the exit surface s3 has a free curved surface shape and the optical axis has a predetermined angle φ2. As another configuration of the embodiment, the optical axis a22 of the light emitted from the light guide body 17 may have a predetermined angle φ2 so as to be tilted to the left in the Y direction with respect to the Z direction. By providing a free curved surface shape on the entrance surface s1 or the emission surface s3 of the light guide body 17, it is possible to design the light distribution characteristics to be different for each position or region in the surface corresponding to the panel surface of the liquid crystal display element 50. be. As a result, it is possible to realize the characteristic of efficiently suppressing the return external light.

[2-6: Light source module]
FIG. 31 is a perspective view showing the appearance of a mounting configuration example of the light source device 10 of the second embodiment as a light source module. In this mounting configuration example, the LED substrate 12 provided with the LED element 14 and the like is mounted as the LED module 120. A heat sink 13 is fixed to the back side of the LED module 120 in the Y direction. The heat sink 13 is arranged so that a plurality of heat radiation fins come out of the light source device case 11. The above-mentioned light source device case 11 is fixed to the front side of the LED module 120 in the Y direction, and the LED collimator 15, the polarization conversion element 21, the light guide body 17, and the like are housed therein. A liquid crystal display element 50 is attached to the upper surface of the light source device case 11 in the Z direction. The liquid crystal display element 50 includes a liquid crystal display panel frame 51, a liquid crystal display panel 52, and an FPC 53. As a result, the video display device 30 is configured as a module. The panel surface of the liquid crystal display element 50 and the display area 4 of the HUD device 1 constitute a horizontally long screen that is relatively long in the X direction and short in the Z direction in this example. Therefore, the light source device 10 has a mounting corresponding to its shape.

In the light source device 10, each component such as the LED substrate 12 and the LED collimator 15 is configured as a module by positioning and fixing to each other by means such as a screw, a positioning pin, and an uneven shape at a position such as an outer periphery. There is. The LED substrate 12 and the LED collimator 15 are positioned and fixed with high accuracy by, for example, fitting the positioning pin and the positioning hole, and being sandwiched and fixed by front and rear parts. Each part of the light source device 10 and the image display device 30 is fixed to the housing 80 of the HUD device 1.

[2-7: Light source module-inside the housing]
FIG. 32 shows the configuration inside the light source device case 11 of the light source device 10. The LED substrate 12 is not shown, and a plurality of (6 in this example) LED elements 14 (14a, 14b, 14c, 14d, 14e, 14f) are provided in the X direction and arranged at a predetermined pitch. An LED collimator 15 having a plurality of (six) collimator elements 15A corresponding to the rear stage of the plurality of LED elements 14 in the Y direction is arranged. Each collimator portion having the recessed portion 153 and the outer peripheral surface 156 is referred to as a collimator element 15A. The LED element 14 is arranged at the center of the top surface of each collimator element 15A. The plurality of collimator elements 15A are integrally formed with the common substrate portion, for example, by a translucent resin. A polarization conversion element 21 is arranged after the LED collimator 15.

The polarization conversion element 21 as a whole has a plate shape that is relatively long in the X direction and short in the Z direction. In the polarization conversion element 21, parts such as the PBS film 211 and the translucent member 214 described above extend in the X direction, and a plurality of parts are arranged symmetrically in the Z direction. The polarization conversion element 21 may be housed in a polarization conversion element holder (not shown). The orientation control plate 16b is arranged after the phase plate of the polarization conversion element 21. An incident portion 171 of the light guide body 17 is arranged at the rear stage of the orientation control plate 16b. The side surface portion 174 in the X direction of the light guide body 171 and the crown portion 175 are provided with attachment portions to the housing 80. The emission surface s3 of the emission portion 173, which is the upper surface of the light guide body 171, has a free curved surface shape as shown in the figure. A diffusion plate 18b is arranged above the emission portion 173 in the Z direction. A form in which the light distribution control plate 16b and the diffusion plate 18b are not provided is also possible. In this embodiment, the synthetic diffusion block 16 is not provided, and the size in the Y direction can be reduced accordingly.

[2-8: Light source unit, LED collimator, polarization conversion element]
FIG. 33 is viewed from the side surface direction (X direction) of the device, which schematically shows the structure, light rays, and the like of the LED substrate 12, the LED element 14, the LED collimator 15, and the polarization conversion element 21 of the light source unit 301. It is a cross-sectional view of YY. The recess 153 of the LED collimator 15 is arranged at a position facing the light emitting surface including the point p1 of the LED element 14 protruding in the Y direction from the main surface of the LED substrate 12 (the surface of the substrate on which the LED element 14 is mounted). ing. The top surface of the recess 153 is arranged so as to be in contact with the light emitting surface of the LED element 14. As described above, the collimator element 15A includes a recess 153 which is a lens portion on the incident side, an outer peripheral surface 156 which is a reflector portion, and an exit surface 154 which is a lens portion on the exit side. The recess 153 has an incident surface 157 on the bottom surface side in the Y direction and a convex curved surface on the incident side. On the emission surface 154, a convex portion 155 that is convex on the emission side is formed at a portion of the recess 153 facing the entrance surface 157. The incident surface 157 and the convex portion 155 form a convex lens function having a light-collecting action.

The light emitted from the point p1 of the LED element 14 passes through the air in the recess 153 of the collimator element 15A, travels as in the example of the illustrated light beam, and exits the recess 153. The light rays emitted from the recess 153 are focused while some of the light rays are reflected by the outer peripheral surface 156 (reflector portion) having a substantially conical shape. The light traveling in the peripheral direction of the optical axis a1 is totally reflected by the paraboloid surface of the outer peripheral surface 156. These light rays are emitted as parallel light in the Y direction through the emission surface 154. The entrance surface of the polarization conversion element 21 is arranged so as to be in contact with the emission surface 154.

The polarization conversion element 21 is incident with parallel light from a plurality (six) LED elements 14 and the collimator element 15A in the X direction. The cross section of the optical axis a1 of each of these LED elements 14 is the same as shown in FIG. 33. The polarization conversion element 21 is composed of a translucent member 214 of a parallelogram column, a translucent member 215 of a triangular column, a PBS film 211, a reflective film 212, a 1 / 2λ phase plate 213, and the like, as described above. There is. The translucent member 214 is a parallelogram in the YZ cross section, and the translucent member 215 is a triangle in the YZ cross section. Each component is arranged vertically symmetrically with respect to the optical axis a1 in the Y direction. A PBS film 211 is provided at the interface between the translucent member 215 arranged on the optical axis a1 and the translucent member 214 arranged above and below the translucent member 215. A reflective film 212 is provided at the interface between the translucent member 214 and the translucent member 215 arranged outside the translucent member 214. A 1 / 2λ phase plate 213 is provided on the surface of the translucent member 214 on the emission side in the Y direction.

Of the light incident on the polarization conversion element 21, the light transmitted through the PBS film 211 through the translucent member 214 (P polarized wave) is emitted from the exit surface through the translucent member 215. Of the light incident on the polarization conversion element 21, the light (S polarized wave) reflected in the Z direction by the PBS film 211 through the translucent member 214 is reflected in the Y direction by the reflecting film 212. The reflected light is emitted as phase-adjusted light (P-polarized wave) from the emission surface of the translucent member 214 through the 1 / 2λ phase plate 213. That is, in the polarization conversion element 21, all the light from the plurality of LED elements 14 is emitted as a P-polarized wave. As a result, the difference in optical path length is small, and the surface uniformity of the luminance distribution is high.

As described above, in the second embodiment, the polarization conversion element 21 is rotated 90 degrees in the XZ plane with respect to the arrangement of the polarization conversion element 21 of the first embodiment (transposed vertically and horizontally). Have been placed. As a result, in the second embodiment, the tolerance and the degree of freedom of the arrangement positions of the plurality of LED elements 14 and the collimator element 15A with respect to the polarization conversion element 21 are higher than those in the first embodiment (described later). Therefore, the light source device 10 can be easily designed and mounted in various ways according to the specifications of the HUD device 1, and the manufacturing yield is improved.

On the incident surface of the polarization conversion element 21, the incident light beam has a limited width 21w corresponding to the translucent member 214 and the like. The collimator element 15A is designed according to the limiting width 21w of the incident luminous flux of the polarization conversion element 21 as in the first embodiment. The diameters of the outer peripheral surface 156 and the exit surface 154 of the collimator element 15A (distance D2 in FIG. 36 described later) are larger than the limit width 21w. A convex portion 155 is provided inside the limited width 21w.

In the light source device 10 of the second embodiment, the image display device 30 using the liquid crystal display element 50, and the HUD device 1, LEDs arranged per unit area in order to realize a predetermined high output and high efficiency LED light source. By increasing the number of elements 14 and the like as much as possible, a large amount of light, brightness, high light utilization efficiency, and in-plane light intensity uniformity are realized. Alternatively, even if the number of LED elements 14 is the same as in the conventional case, the area and size required for the device can be reduced.

[2-9: Polarization conversion element]
FIG. 34A is a perspective view showing a configuration such as component arrangement of a set of polarization conversion element portions of the polarization conversion element 21. The approximate positions of the plurality of LED elements 14 and the plurality of collimator elements 15A arranged corresponding to the polarization conversion element 21 are also shown by broken lines. Let N be the number of LED elements 14 and the like arranged in the X direction. Here, the case of N = 3 is shown. In the XZ plane on the front side in the Y direction of the polarization conversion element 21, each of the plurality of points q indicates a point through which the optical axis a1 from the point p1 of each LED element 14 passes. The circle around the point q corresponds to the end of the outer peripheral surface 156. The outer peripheral surface 156 having a substantially conical shape is shown by a broken line.

The PBS film 211, the reflective film 212, the 1 / 2λ phase plate 213, the translucent member 214, and the translucent member 215, which are the components constituting the polarization conversion element 21, extend in the X direction. Each of these parts is arranged parallel to a plane (XZ plane) orthogonal to the optical axis a1. Each of these parts is arranged in a position and shape vertically symmetrical in the Z direction with respect to a virtual plane which is an XY plane formed by the Y direction and the X direction corresponding to the optical axis a1 and the central axis of the collimator element 15A. Has been done. The translucent member 215 arranged at the position of the optical axis a1 in the Z direction has a triangular prism shape. The two translucent members 214 arranged vertically symmetrically with respect to the translucent member 215 have a quadrangular prism shape. Further, the two translucent members 215b arranged outside them have a triangular prism shape having a right triangle in cross section. The PBS film 211 and the reflective film 212 are arranged as slopes having a predetermined positive / negative angle ε with respect to the optical axis a1 in the Y direction. As shown in FIG. 25B, the polarization conversion element 21 may have a configuration in which the upper component 21u and the lower component 21d are bonded on the bonding surface 216. Further, it is desirable that the bonding surface 216 has an optically transparent structure after bonding. In this configuration, the upper component 21u and the lower component 21d can be configured by the same component, respectively. That is, if the upper component is rotated by 180 ° around the Z axis shown in the figure and further rotated by 180 ° around the Y axis, the lower component is arranged. With this configuration, common parts and simplification of the configuration can be achieved, and the cost can be further reduced.

[2-10: Multiple LED elements, collimators, deflection conversion elements]
FIG. 35 shows an XZ plane seen from the Y direction with respect to a configuration example in which a plurality of (N) LED elements 14 and a plurality of collimator elements 15A are arranged in the X direction with respect to the polarization conversion element 21. Further, FIG. 35 shows, as a modification, a configuration example in which two sets of polarization conversion elements 21 are arranged in the Z direction. In FIG. 35A, the first polarization conversion element portion 21-1 is arranged on the upper side in the Z direction, and the second polarization conversion element portion 21-2 is arranged on the lower side. The structure of each polarization conversion element unit is the same as shown in FIG. 34.

In the X direction, points q corresponding to the plurality of LED elements 14 and the plurality of collimator elements 15A are arranged at a distance D1 having a predetermined pitch. In (a), the positions of the points p are the same in the upper and lower polarization conversion element units. In the XX plane, the points q corresponding to the light emitting axes of the plurality of LED elements 14 are arranged in a rectangular shape. Further, the diameter of the circular region corresponding to the outer peripheral surface 156 of the collimator element 15A is indicated by the distance D2. In this example, a plurality of collimator elements 15A are arranged in the X direction as close as possible while ensuring individual distances D2. The surface of the LED element 14 is arranged so as to fit in the top surface of each recess 153.

(B) of FIG. 35 is a case where, as another configuration example, the arrangement positions of the points q of the plurality of LED elements 14 and the like are shifted in the upper and lower polarization conversion element units 21-1 and 21-2 in the Z direction. .. The positions of the LED elements 14 and the like of the lower polarization conversion element 21-2 are deviated from the upper polarization conversion element portion 21-1 by half the pitch (distance D2). In the XX plane, the points q corresponding to the light emitting axes of the plurality of LED elements 14 and the like are arranged in a triangle. Similarly, if necessary, it is possible to arrange not only two rows but also a plurality of sets of polarization conversion element units in the Z direction.

As described above, in the second embodiment, there are few restrictions on the arrangement of the plurality of LED elements 14 and the like in the X direction with respect to the arrangement configuration of the polarization conversion element 21, and the degree of freedom of arrangement is high. In the above-described first embodiment, for example, as shown in FIG. 4, a plurality of components of the polarization conversion element 21 extend in the Z direction and are arranged in the X direction. Therefore, the polarization conversion element 21 is separately configured as a plurality (two) sets of polarization conversion element units in the X direction, and the position of the optical axis 15c in the X direction and the position corresponding to each set It has a constraint width of 21w. Corresponding to the configuration of such a polarization conversion element 21, the LED element 14 and the collimator unit need to be arranged at a predetermined position. Therefore, for example, even if a large number of LED elements 14 and the like are to be arranged within a predetermined size in the X direction, they can be arranged only at a predetermined distance or more due to restrictions.

On the other hand, in the second embodiment, as shown in FIGS. 34 and 35, there are few restrictions on the arrangement of parts such as the LED element 14 in the X direction as compared with the first embodiment, and the degree of freedom of arrangement is high. The polarization conversion element 21 is not divided into a plurality of parts (sets) in the X direction, and the parts are continuously extended. Therefore, in the X direction, the LED element 14 and the like can be arranged at a position that is free to some extent. For example, as shown in FIG. 35A, it is possible to arrange a plurality of (N) LED elements 14 and the like in the X direction at a pitch (distance D1) as short as possible. By arranging a large number of LED elements 14 and the like within a predetermined size in the X direction, the amount of light from the light source can be increased and the size of the device can be contributed.

[2-11: Multiple LED elements (N = 5)]
FIG. 36 shows an explanatory diagram regarding an arrangement configuration of a plurality of LED elements 14, a plurality of collimator elements 15A, a polarization conversion element 21, and the like in the second embodiment. In this embodiment, a case where N = 5 is shown as the number of LED elements 14 and the like arranged in the X direction. 35 (a) shows the configuration of the XY plane, (b) shows the configuration of the XY plane of the corresponding polarization conversion element 21, and (c) shows the configuration of the corresponding polarization conversion element 21. The configuration of the YY plane is shown. In this example, the collimator elements 15a to 15e are provided as the collimator elements 15A in correspondence with the LED elements 14 (14a to 14e).

The width of the LED collimator 15 and the polarization conversion element 21 in the X direction is shown by the distance DA. The height of the polarization conversion element 21 in the Z direction is shown in the distance DB. The width of a portion of the distance DB that is vertically symmetrical with respect to the optical axis a1, which is half of the distance DB, is indicated by the distance DC. The thickness of the polarization conversion element 21 (excluding the 1 / 2λ phase plate 213) in the Y direction is shown by the distance DD.

In this embodiment, the distance DB of the polarization conversion element 21 is, for example, 17.6 ± 0.2 mm, the distance DC is 8.8 ± 0.1 mm, and the distance DD is 4.4 ± 0.1 mm. The angle ε of the slopes of the PBS film 211 and the reflective film 212 is (45 ° ± 20') when the units are degrees (°) and minutes ('). The 1 / 2λ phase plate 213 (Half wave plate) has a shape that does not protrude from the boundary, the length in the X direction is the same as the length of the translucent member 214, etc., and the width in the Z direction is the translucent member. It is the same as the width of the exit surface of 214. The distance DA of the polarization conversion element 21 is, for example, 44 ± 0.2 mm in the first type example having a relatively small size, and 74 ± 0.2 mm in the second type example having a relatively large size.

[2-12: Comparative example]
FIG. 37 also shows the configuration of the comparative example with respect to the configuration of N = 5 in FIG. 36. In this comparative example, N = 5 LED elements 14 and collimator elements 15A are also arranged in the X direction. In this comparative example, the polarization conversion element 21 is configured by using five sets of polarization conversion element units in the X direction. The distance DB of the width of one set of polarization conversion element units is the same as the width of FIG. 36. In this comparative example, the pitch (distance D1b) of the arrangement of the LED element 14 and the collimator element 15A is larger than the pitch (distance D1) of FIG. 36 due to the limitation corresponding to the configuration of the polarization conversion element 21, and the X direction of the entire device. The size of (distance DAb) is larger than the size of FIG. 36 (distance DA).

As described above, according to the second embodiment, the device can be made smaller than the comparative example. Alternatively, according to the second embodiment, when the predetermined size (distance DAb) is the same as that of the comparative example, a larger number of LED elements 14 and the like can be arranged within the range to increase the amount of light. In the light source device 10 of the second embodiment, the number (N) of the LED elements 14 that can be arranged within a predetermined width in the X direction can be increased, and brighter illumination light can be generated. Alternatively, the width in the X direction can be made smaller in the light source unit 301 or the like provided with a predetermined number of LED elements 14.

According to the second embodiment, a plurality of LED elements 14 and the like can be arranged relatively freely within a predetermined condition with respect to the polarization conversion element 21 in the X direction. Therefore, according to the specifications of the HUD device 1 (for example, the size of the display area 4 and the like), it is possible to easily mount the light source device 10 by changing the number and positions of the arrangements of the LED elements 14 and the like. In various mountings, the configuration of the polarization conversion element 21 can be made common, and the parts can be used in common, so that it can be manufactured at low cost.

[2-13: Implementation example of a plurality of LED elements (N = 5)]
FIG. 38 shows the case of N = 5 corresponding to FIG. 36 as an implementation example including an arrangement of a plurality of LED elements 14 and the like in the light source device 10 of the second embodiment. (A) of FIG. 38 shows a top view in the XY plane, and (b) shows a side view in the corresponding YY plane. In the X direction, the approximate width of the LED substrate 12, the LED collimator 15, the polarization conversion element 21, the polarization control plate 16b, the light guide body 17, etc. is shown by the distance DA1. Within the width of the distance DA1, the five LED elements 14 and the corresponding five collimator elements 15A (15a to 15e) in the X direction are arranged at a distance D11 at a predetermined pitch. For example, in the case of mounting the light source device 10 with priority on small size, low cost, low power consumption, etc., N = 5 LED elements 14 and the like are provided within a predetermined distance DA1 as in the mounting example of FIG. 38. Be placed.

[2-14: Implementation example of a plurality of LED elements (N = 6)]
FIG. 39 shows the case where N = 6 as the light source device 10 of the modified example and includes the arrangement of a plurality of LED elements 14 and the like in the same manner as in FIG. 38. In the X direction, the approximate size of the LED substrate 12 and the like is indicated by the distance DA2. Within the width of the distance DA2, six LED elements 14 (14a to 14f) and six corresponding collimator elements 15A (15a to 15f) in the X direction are arranged at a predetermined pitch (distance D12). For example, in the case of mounting in which the number of LEDs in the X direction is to be increased as much as possible to increase the amount of light source light, as shown in FIG. 39, N = 6 LED elements 14 and the like have a predetermined pitch as short as possible within a predetermined distance DA2. Arranged at a distance D12.

As described above, in the second embodiment, since the degree of freedom in arranging the plurality of LED elements 14 and the like in the X direction is high with respect to the configuration of the polarization conversion element 21, any of the embodiments of FIGS. 38 and 39. It can be easily realized. That is, mounting in which the number (N) of the LED elements 14 is changed according to the specifications of the HUD device 1 and the like can be realized relatively easily. For example, it is easy to reduce the number of LEDs (N) from the configuration of FIG. 39 and change to the configuration of FIG. 38.

[2-15: Light guide body]
FIG. 40 is a perspective view showing a free curved surface shape and the like of the emission surface s3 of the emission portion 173 of the light guide body 17. 40 (a) is a perspective view, and (b) is a configuration of a YY plane with a side surface portion 174 as seen. In (a), on the exit surface s3 of the exit portion 173, the free curved surface portion 173a is provided inside the flat surface portion 173b on the outer circumference. In (b), the incident surface s1 of the incident portion 171 is a slope having an inclination angle φ4 with respect to the vertical Z direction. The crown surface s5 of the crown 175 also has a mounting portion for the housing. The exit surface s3 is a slope having an angle φ1 with respect to the horizontal plane. On the slope, it has a free curved surface portion 173a.

The emission surface s3 of the emission unit 173 of the light guide body 17 has a shape corresponding to the panel surface of the liquid crystal display element 50 arranged later. The exit surface s3 and the incident surface s1 are different in shape and area. The area of the exit surface s3 is larger than the area of the incident surface s1. In the incident portion 171 the light distribution angle in one direction (for example, the Z direction) may be wider than the light distribution angle in the other direction (for example, the X direction) orthogonal to the one direction. In the emitting unit 173, the light distribution angle in one direction (for example, the Y direction) may be wider than the light distribution angle in the other direction (for example, the X direction) orthogonal to the one direction. The incident surface s1 and the exit surface s3 may have different curvatures in the plane. For example, the curvature may be larger at the peripheral portion than at the central portion in the plane.

FIG. 41 shows the structure of the reflective portion 172 and the like of the light guide body 17. FIG. 41 (a) shows the configuration of the YY plane, and FIG. 41 (b) shows a partial enlargement of the reflective surface s2. In (a), the distance between the exit surface s3 and the reflection surface s2 is shown as the inter-plane distance Dt. The interplane distance Dt has a maximum distance Dtmax near the incident surface s1 and a minimum distance Dtmin near the parietal surface s5 (Dtmax> Dtmin). The height of the crown surface s5 corresponding to the distance Dtmin is lower than the height of the incident surface s1 corresponding to the distance Dtmax. In this embodiment, Dtmax / Dtmin≈2.

The reflection surface s2 is basically arranged as a slope having a predetermined angle with respect to the horizontal plane. The reflective surface s2 has a sawtooth shape (staircase shape) in which the reflective surface 172a and the connecting surface 172b are alternately repeated, as in the first embodiment in detail. (B) shows a portion of the reflecting surface 172a and the connecting surface 172b having n = 1 to 9 near the incident surface s1. (C) shows a portion of the reflecting surface 172a and the connecting surface 172b having n = 64 to 75, which is close to the crown surface s5. In the same manner as described above, the pitch of the plurality of reflecting surfaces 172a in the Y direction is indicated by P1 or the like, the angle of the reflecting surface 172a with respect to the horizontal plane is indicated by an angle αn, and the angle of the connecting surface 172b with respect to the reflecting surface 172a is indicated by an angle βn. ..

As described above, the structure of the light guide body 17 including the incident portion 171, the reflecting portion 172, the emitting portion 173, and the crown portion 175 realizes a predetermined orientation control, and the emitted light has a tilt angle φ2 with respect to the Z direction. Axis a22 is configured (corresponding to the configuration in FIG. 30).

Further, such a shape of the light guide body 17 also has an advantage that it can be easily manufactured at the time of manufacturing. When the light guide body 17 is produced in large quantities at low cost, it is effective to produce the light guide body 17 by using a manufacturing method such as injection molding. When the manufacturing method is used, as a comparative example, in the case of the light guide body 17 having a substantially triangular cross section as shown in FIG. 8, it is possible to ensure the accuracy of injection molding at the side portion corresponding to the apex of the acute angle of the triangle. There is a problem that it is relatively difficult and expensive. Specifically, regarding the cooling rate of the molten resin in the mold at the time of injection molding, there is non-uniformity according to the difference in the portion of the light guide body 17 (the incident surface and the side portion on the opposite side thereof), so that the molding is highly accurate. Is relatively difficult. Since the shape of the light guide body 17 is designed to have a predetermined orientation control characteristic, when the shape of the light guide body 17 after injection molding has a large deviation from the design shape, the light distribution control is performed. The quality of the property is reduced.

On the other hand, in the second embodiment, as shown in FIG. 41, the cross section of the light guide body 17 is substantially trapezoidal and has a crown portion 175. In the second embodiment, the difference in shape between the incident portion 171 and the crown portion 175 is smaller than that in the comparative example. Therefore, when the light guide body 17 is manufactured by the injection molding manufacturing method, the cooling rate of the molten resin in the mold at the time of injection molding is non-uniform according to the difference between the portions (incident surface 171 and the crown 175). Is suppressed. Therefore, the light guide body 17 has an advantage that more accurate molding can be realized, the quality of the characteristics of the light distribution control can be improved, and mass production can be performed at low cost. The processing example of the mold at the time of manufacturing the light guide body 17 of the second embodiment, particularly the reflecting portion 172, is the same as that of FIG. 18 described above.

[2-16: Orientation control]
FIG. 42 shows the configuration of the orientation control of the light source device 10 and the image display device 30 of the second embodiment, and the optical axis of the illumination light of the light source device 10 and the image light of the image display device 30 and each light ray are viewed from the X direction. It is shown by the seen YZ cross section. The reflecting surface 172a and the connecting surface 172b of the light guide body 17 are shown schematically by enlarging them from the actual state. In this embodiment, the incident surface s1 of the light guide body 17 is a plane arranged diagonally with an angle φ4 with respect to the Z direction. The optical axis a11 in the Y direction from the point p1 of the LED element 14 is incident on the point p2 of the incident surface s1 of the light guide body 17 to cause a predetermined refraction, and becomes the optical axis a12. The optical axis a12 is reflected by the point p3 of the reflecting surface s2 and becomes the optical axis a21 in the Z direction. The emission surface s3 has a free curved surface shape that is diagonally arranged with an angle φ1 with respect to the Y direction, and has a predetermined refraction characteristic. The optical axis a21 in the Z direction from the reflection surface s3 is refracted through the point p4 on the free curved surface of the emission surface s3, and becomes the optical axis a22 having an angle φ3 with respect to the Z direction. The illumination light of the optical axis a22 is incident on the point p5 on the panel surface of the liquid crystal display element 50. The image light generated by the liquid crystal display element 50 becomes the optical axis a23 also having an angle φ3. The light ray L30 of the image light of the optical axis a23 is incident on the above-mentioned refraction element 43.

Further, in this embodiment, the diffuser plate 18a is arranged above the exit portion 173 of the light guide body 17 in the Z direction and near the back surface of the liquid crystal display element 50. The diffuser plate 18a and the liquid crystal display element 50 are arranged substantially on a horizontal plane. Specifically, the diffusion plate 18a and the liquid crystal display element 50 are arranged on a surface having an angle φ5 with respect to a horizontal plane.

In the illumination optical system 302, complicated light distribution control is required for the above-mentioned suitable illumination light and in order to realize prevention of return external light. This light distribution control is realized by the orientation control shown in FIG. 42. The light distribution control along the YZ plane of FIG. 42 is represented by the optical axes a11, a12, a21, a22, a23 and the like. This orientation control is realized by the refraction angle of the incident surface s1 of the light guide body 17, the reflection angle of the reflecting surface s2, the refraction angle of the emitting surface s3 due to the shape of the free curved surface, and the like. Further, the light distribution control in the X direction is realized by the refraction angle or the like due to the free curved surface shape of the emission surface s3. Further, the light distribution control plate 16b controls light diffusion in the Z direction and the like. Further, the diffuser plate 18b controls light diffusion in the X direction and the Y direction. Due to the characteristics of the orientation control of the light source device 10 of the second embodiment, the degree of freedom corresponding to the orientation angle of the illumination light can be improved as compared with the conventional technique, and the characteristics of the suitable video light required for the HUD device 1 can be improved. Can be improved. It becomes easy to mount the light source device 10 having a predetermined orientation control characteristic according to the characteristics of the adjustment optical system 40 and the liquid crystal display element 50 of the HUD device 1. For example, the characteristics of the illumination light can be adjusted by designing the free curved surface shape of the emission portion 173 of the light guide body 17. In addition, it is possible to adjust the characteristics of suitable image light and light distribution control for preventing return external light.

[2-17: Light distribution control plate]
FIG. 43 shows a cross-sectional configuration of the light distribution control plate 16b in the light source device 10 of the second embodiment. FIG. 43A shows an XY cross section of the light distribution control plate 16b. The light distribution control plate 16b has a flat surface on the incident side and a serrated surface on the emitted side in the Y direction. FIG. 43 (b) shows a partial enlargement of the emission surface of the light distribution control plate 16b. On the exit surface, a plurality of triangular cross sections are repeatedly formed as a texture in the Z direction. As for the slopes of the plurality of triangles, the first slope having a positive angle γ with respect to the X direction and the second slope having a negative angle γ with respect to the X direction are alternately repeated. The pitch of the arrangement of the triangles in the X direction is shown by the distance D43. In this embodiment, the angle γ = 30 degrees and the pitch distance D43 = 0.5 mm. The light from the polarization conversion element 21 is diffused in the X direction of the incident portion 171 by the action of the texture of the emitting surface. The light distribution control plate 16b may be, for example, a diffusion plate having an elliptical diffusion angle.

The orientation control plate 16b has light diffusivity in the X direction. The diffuser plate 18b has light diffusivity in the Y direction. By the action of the orientation control plate 16b and the diffusion plate 18b, the intensity distribution of the emitted light from the light guide 17 in the plane is made uniform, and a suitable planar illumination light is obtained. In the second embodiment, as compared with the first embodiment, since the plurality of LED elements 14 and the like can be arranged at close positions in the X direction, the uniformity in the X direction is further improved in combination with the diffusivity of the orientation control plate 16b. do. Note that the uniformity in the Z direction can be realized by controlling the ratio of the reflecting surface 172a formed on the reflecting portion 172 of the light guide body 17 to the connecting portion 172b, as described with reference to FIG. 10 of the first embodiment. Is. As a result, the minimum necessary diffusivity can be realized, the light utilization efficiency is improved, and a suitable planar illumination light can be generated.

[2-18: Functional scattering surface]
As a modification of the second embodiment, a predetermined functional scattering surface may be provided on at least one of the orientation control plate 16b, the diffusion plate 18b, and the entrance surface s1 or the emission surface s3 of the light guide body 17. good. In that case, the characteristics of the functional scattering surface are the same as those in FIG. 16 described above.

[2-19: Light guide body-light diffusivity]
In the second embodiment, the incident surface s1 of the incident portion 171 of the light guide body 17 may be provided with the characteristic of light diffusion in the Z direction. In that case, the characteristics of the incident surface s1 are the same as those in FIG. 17 described above.

[2-20: Light guide-free curved surface shape]
The details of the free curved surface shape of the exit portion 173 of the light guide body 17 in the second embodiment will be described with reference to FIGS. 40 and 44. The free curved surface is one of the curved surfaces that can be treated as a three-dimensional object such as CAD, and is a curved surface that can be expressed by a high-order equation by setting some intersections and curvatures in space.

First, in FIG. 40A described above, the free curved surface portion 173a is provided inside the flat surface portion 173b of the outer frame in the emission surface s3 of the emission portion 173. An example of how to take the reference coordinate system on this free-form surface is shown by (x, y, z). It has an x-axis and a y-axis that are orthogonal to each other through the point K2 (corresponding to the point p4) at the center of the free-form surface. The x-axis has a correspondence with the X direction, and the y-axis has a correspondence with the Y direction. The reference position of the exit portion 173 of the light guide body 17 is shown by a broken line. In this example, the reference position is the starting position of the slope near the incident surface s1 side. In FIG. 40 (b), the distance from the reference position of the exit portion 173 of the light guide body 17 to the x-axis (point K2) of the reference coordinate system of the free curved surface is shown by the distance Dy0. In this example, Dy0 = 18 mm. The center of the y-axis was the center of the light guide body 17. Further, the angle formed by the horizontal plane and the y-axis is set to the angle θy, and in this example, θy = 17 °. The z-axis of the reference coordinate system is perpendicular to the x-axis and the y-axis from the point K2, and the inward direction of the exit surface s3 is shown as positive.

The range of the free curved surface was -21 mm ≤ x ≤ 21 mm and -15 mm ≤ y ≤ 16 mm. Generally, the width in the X direction is 42 mm and the width in the Y direction is 31 mm. Further, in this embodiment, when the value of z (x, y) is negative, it is forcibly set to 0. In other words, as shown in FIG. 40 (b), on the exit surface s3, the outside is cut as a flat surface, and a concave portion of a free curved surface exists inward from the plane as shown by a dotted line. As another embodiment, a structure in which a convex portion of a free curved surface exists from the exit surface to the outside (emission direction) may be used.

FIG. 44 shows an equation and a coefficient thereof that define the free curved surface shape of the emitting portion 173 of the light guide body 17 in the second embodiment. FIG. 44A shows Equation 1, which is a general expression of a free-form surface equation. The free curved surface is represented by z (x, y) = Σ {ai · bi (x, y)} as shown in Equation 1. Σ is an addition from subscript i = 0 to 14. ai and bi indicate coefficients and variables. z (x, y) represents a z value corresponding to the value of the position coordinate of (x, y). The unit is mm.

FIG. 44 (b) shows the coefficients and variables of Equation 1 in tabular form. For example, when i = 0, b0 = 1 and a0≈1.0269. At i = 1, b1 = x and a1≈−0.0015. At i = 2, b2 = y and a2≈−0.0032. At i = 3, b3 = x ^ 2, a3≈−0.0052. At i = 14, b14 = y ^ 4 and a14 = 5.3049E-06. E is an exponent, for example E-06 indicates 1/10 to the 6th power. Others are as shown in the table. z (x, y) = a1 ・ b1 (x, y) + a2 ・ b2 (x, y) + …… + a14 ・ b14 (x, y) ≈1.0269-0.0015x-0.0032y-0.0052x ^ 2 + …… + 5.3049 / (10 ^ 6) × y ^ 4.

[2-21: Effect, etc.]
As described above, according to the main configuration of the light source device 10 of the second embodiment, as in the first embodiment, it is compact and lightweight, has high light utilization efficiency, and is easily modularized as a planar light source. Can provide a light source device that can be used for. More specifically, it is possible to further improve the light utilization efficiency from the LED light source and uniform lighting characteristics. In addition, it is possible to provide a light source device suitable as a light source for lighting that can be manufactured at low cost. Further, it is possible to provide an image display device 30 that generates suitable image light and a light source device 10 that generates suitable illumination light according to the characteristics of the HUD device 1 and the liquid crystal display element 50. Further, it is possible to provide the HUD device 1 which can prevent return external light and has good display characteristics of a virtual image. By controlling the light distribution in the light source device 10, it is easy to mount the image light by expanding the area of the image light with respect to the illumination light.

(1) In the light source device 10 of the second embodiment, the light guide body 17 has a free curved surface shape on at least one of the entrance surface s1 and the emission surface s3 to realize a predetermined light distribution control. As a result, the characteristics of the light distribution control that realizes a suitable illumination light and a return external light prevention function are realized.

(2) In the light source device 10, the image display device 30, and the HUD device 1, the axes (normal slopes) of the liquid crystal display element 50 and the refraction element 43 are predetermined with respect to the optical axis of the light emitted from the light guide body 17. It is slanted at an angle. The light guide body 14 has a trapezoidal cross section, and the emission surface s3 is arranged as a slope with respect to the horizontal. As a result, the characteristics of the light distribution control that realizes a suitable image light and a return external light prevention function are realized.

(3) In the present light source device 10, the light guide body 17 has the same structure of the reflecting portion 172 as that of the first embodiment, whereby the light utilization efficiency is high and suitable illumination light is realized.

(4) The light source device 10 has a structure in which an LED element 14, an LED collimator 15, a polarization conversion element 21, and the like are combined in addition to the structure of the light guide body 17, and the orientation of the light source device 10 is controlled by the structure. Realizes the characteristics. For example, in the polarization conversion element 21, the parts extend in the X direction, and a plurality of LED elements 14 and the like are arranged in the X direction correspondingly. As a result, the burden of light distribution control required by the liquid crystal display element 50 and the adjusting optical system 40 (refractive element 43, etc.) can be reduced by the predetermined light distribution control in the light source device 10, and measures against external light flare can be easily taken. Become.

[2-22: First modification example]
FIG. 45 shows the configuration of the light source device 10 of the first modification of the second embodiment in the YY plane. In this first modification, the incident surface s1 of the incident portion 171 of the light guide body 17 has a free curved surface shape, and the emitted surface s3 of the emitted portion 173 has a planar shape. A predetermined light distribution control characteristic is realized by the structure including the free curved surface shape of the incident surface s1. The incident surface s1 of the incident portion 171 has an inclination angle φ4 with respect to the Z direction as a reference plane. The reference plane of the incident surface s1 has a free curved surface shape. Further, in the configuration example of FIG. 45, the optical axis from the reflecting portion 172 and the optical axis from the emitting surface s3 are inclined to the left side in the Y direction with respect to the Z direction at an angle φ3, and are inclined to the axis of the liquid crystal display element 50. On the other hand, it is tilted at an angle of φ2.

[2-23: Second modified example]
FIG. 46 shows the configurations of the light source device 10 and the image display device 30 of the second modification of the second embodiment in the YZ plane. In this second modification, as a configuration point different from the above-described embodiment, not only the exit portion 173 of the light guide body 17 but also the incident surface s1 of the incident portion 171 has a free curved surface shape. Similarly, the incident surface s1 of the incident portion 171 has an inclination angle φ4 with respect to the Z direction as a reference plane. It has a free curved surface shape that is convex on the incident side with respect to the reference plane of the incident surface s1. It is designed to have a predetermined light distribution control characteristic of the light guide body 17 by combining the characteristic of the free curved surface of the incident surface s1 and the characteristic of the free curved surface of the emitting surface s3. As described above, by forming both the incident portion 171 and the emitting portion 173 into a free curved surface shape, the degree of freedom of light distribution control is increased, and more precise and more complicated light distribution control can be realized. As a result, it is possible to realize more precise characteristics such as suitable image light and prevention of return external light.

[2-24: Third modified example]
FIG. 47 shows a perspective view of an embodiment of a relatively large light source device 10 that realizes a light source for a large area as the light source device 10 and the image display device 30 of the third modification of the second embodiment. This third modification has a linear optical axis in the Z direction corresponding to the vertical. Correspondingly, in this third modification, the light guide body 19 that guides light in the Z direction is provided. The light guide body 19 is a light distribution control member that realizes predetermined light distribution control characteristics.

In FIG. 47 (a), the arrangement of parts in the case is shown, and the LED board 12 and the like are not shown. A plurality of LED elements 14, an LED collimator 15, a polarization conversion element 21, an orientation control plate 16b, a light guide body 19, and a liquid crystal display element 50 are arranged in order from bottom to top in the Z direction. Each of these parts is substantially flat in the XY plane, and the side in the X direction is longer than the side in the Y direction. The side in the X direction corresponds to the horizontally long side of the liquid crystal display element 50 and the display area 4 of the HUD device 1.

The polarization conversion element 21 is configured by using two sets of polarization conversion element units 21a and 21b arranged in the Y direction. The first polarization conversion element portion 21a is provided on the left side in the drawing in the Y direction, and the second polarization conversion element portion 21b is provided on the right side, and they are arranged adjacent to each other. The polarization conversion element portions of each set have the same structure, and the parts extend in the X direction.

A plurality of LED elements 14 and collimator elements 15A are arranged in the X direction corresponding to the configuration of the polarization conversion element 21. For example, N = 9 LED elements 14 (14-1, 14-2, ..., 14-9) are arranged at a predetermined pitch with respect to the polarization conversion element unit 21a in the X direction. Nine collimator elements 15A are arranged in the X direction corresponding to those LED elements 14. Similarly, with respect to the other polarization conversion element unit 21b, N = 9 LED elements 14 (14-10, 14-11, ..., 14-18) and the corresponding collimator element 15A have a predetermined pitch in the X direction. It is arranged in. That is, in this embodiment, nine LED elements 14 in the X direction, two rows in the Y direction, and a total of 18 LED elements 14 and collimator elements 15A are arranged in the XY plane. As a result, a planar light source having a relatively large area is configured.

In the Z direction, the light guide body 19 is arranged in the space between the light distribution control plate 16b and the liquid crystal display element 50. The light guide body 19 generally has a saddle shape as shown in the figure. Above the light guide body 19, the panel surface of the liquid crystal display element 50 is substantially arranged on a horizontal plane.

FIG. 47 (b) shows a partial cross-sectional view of (a), and shows a YY cross section at a position of the LED element 14-5 near the center in the X direction. The light guide body 19 has an incident portion 191 (including an incident surface) on the lower side in the Z direction and an emitting unit 192 (including an emitting surface) on the upper side in the Z direction. The entrance surface and the exit surface each have a free curved surface shape. The free-form surfaces of the incident surface and the exit surface have a convex curve in the Z direction (exit side) when viewed in the YZ cross section. The free-form surfaces of the entrance surface and the exit surface have a concave curve in the Z direction when viewed in the XX cross section. The optical axes a31 and a32 passing through the polarization conversion element 21 and the light guide body 19 are shown. The optical axes a31 and a32 are subjected to predetermined refraction, light diffusion, and the like due to the free curved surface. A predetermined light distribution control characteristic is designed by the free curved surface shape of the light guide body 19. As a result, according to the light source device 10 of the third modification, characteristics such as suitable image light and prevention of return external light are realized.

The free curved surface shape of the light guide body 19 of FIG. 47 will be described with reference to FIGS. 48 and 49. FIG. 48 shows a perspective view of the light guide body 19 and shows an example of how to take a reference coordinate system (x, y, z) of a free curved surface. The reference coordinates of the emission surface of the emission unit 192 are coordinates tilted at an angle θy (for example, θy = 1 °) with respect to the direction of the horizontal plane indicated by the alternate long and short dash line. The y-axis is based on the coordinates of a position (point K4) offset by a predetermined distance (for example, −1.2 mm) from the center position of the light guide body 19. There is no offset of the reference coordinates of the incident surface on both the angle θy and the y-axis.

FIG. 49 shows a free-form surface equation and coefficients. (A) of FIG. 49 shows the same free-form surface equation as described above, (b) shows an example of the coefficient and the variable of the exit surface of the exit portion 192, and (c) shows the incident surface of the incident portion 191. An example of coefficients and variables is shown. The range of the free curved surface of the light guide body 19 was −40 mm ≦ x ≦ 40 mm and −22 mm ≦ y ≦ 2 mm. Approximately, the width in the X direction is 80 mm and the width in the Y direction is 24 mm. When the value of z (x, y) was smaller than −8 mm on the incident surface, the value was forcibly set to −8 mm. In other words, the portion that is largely convex downward in the Z direction (near both ends in the Y direction in the figure) is cut at a position of −8 mm to form a flat surface.

[2-25: Fourth modified example]
FIG. 50 shows an example in which a small light source is realized in a relatively small area as the light source device 10 and the image display device 30 of the fourth modification of the second embodiment. FIG. 50A shows a perspective view of the inside of the case of the light source device 10 with the liquid crystal display element 50 attached, and FIG. 50B shows a partial cross section with the liquid crystal display element 50 removed. The perspective view including the light distribution and the light distribution are shown. In this light source device 10, the optical axis a1 of the LED element 14 is in the Y direction. In the Y direction, the LED substrate 12, the plurality of LED elements 14, the LED collimator 15, the polarization conversion element 21, and the light distribution control plate 16b are arranged in this order. A light guide body 19b is arranged after the light distribution control plate 16b. In other words, the light guide body 19b is a light distribution control plate, and has a predetermined light distribution control characteristic of guiding light in the Y direction substantially. The light guide body 19b has an incident portion 19b1 and an emitting portion 19b2. Due to its characteristics, the light guide body 19b has a free curved surface shape on both the entrance surface and the exit surface. In the YZ cross section of the light guide body 19b, the entrance surface and the exit surface are free curved surfaces including a convex curve on the entrance side in the Y direction.

A reflection mirror 500 is further arranged on the emission side of the light guide body 19b in the Y direction in a state of having an angle of inclination with respect to the horizontal plane. The optical axis in the Y direction is substantially converted into an optical axis in the Z direction through reflection by the reflection mirror 500. A diffuser plate 18b and a liquid crystal display element 50 are arranged on an XY plane above the reflection mirror 500 in the Z direction.

In the plurality of LED elements 14, N = 5 LED elements 14 (14a to 14e) are arranged as close as possible at a predetermined pitch in the X direction. Similarly, in the LED collimator 15, a plurality of collimator elements 15A are arranged in the X direction. As a result, a planar light source unit 301 having a relatively small area is configured. The light from the LED element 14 in the Y direction passes through the light distribution control plate 16b and then is incident on the incident surface of the incident portion 19b1 of the light guide body 19b. The light incident on the incident surface of the incident portion 19b1 is guided while being refracted along the shape of the free curved surface, and is emitted from the emitting surface of the emitting portion 19b2. Specifically, as in the example of the light ray shown in (b), the emitted light is focused toward the reflection mirror 500, and the range of the light ray in the Z direction is narrowed. For example, a ray passing through a position above the central optical axis in the Z direction is converted into a ray pointing diagonally downward, and a ray passing through a position below the center in the Z direction is converted into a ray pointing diagonally upward. ..

The light that has passed through the light guide body 19b is reflected upward in the Z direction by the reflection mirror 500. The reflected light passes through the diffuser plate 18b and is diffused, and is incident on the panel surface of the liquid crystal display element 50 as illumination light. This illumination light is collected through the light guide body 19b and the reflection mirror 500, and is converted into illumination light having a relatively small area. In the plane of the diffuser plate 18b, the illumination area 501 by condensing light is shown by a dotted line. Illumination light passes through this illumination area 501. The illumination area 501 is smaller than the area of the panel surface of the liquid crystal display element 50. In this embodiment, as the illumination light for the liquid crystal display element 50, as shown in the illumination area 501, a surface-like illumination light having a small area may be used. For example, the display area 4 of the HUD device 1 has a relatively small area. Corresponds to the case of. For such applications, the configuration of the light source device 10 as in this fourth modification is suitable.

[2-26: Fifth variant example]
FIG. 51 is a perspective view showing the configuration of the light source device 10 and the image display device 30 of the fifth modification of the second embodiment. In FIG. 51, the configuration of the portion on the right side in the Y direction from the broken line 511 in the Z direction is the same as the configuration of FIG. 42 and the like described above, and has a reflection portion 173, an emission portion 172, and a crown portion 175. The configuration of the portion on the left side in the Y direction from the broken line 511 is different. In this configuration, the optical axis a51 of the LED element 14 is substantially along the vertical Z direction and proceeds from top to bottom. The structures of the heat sink 13, the LED substrate 12, the LED element 14, the LED collimator 15, the polarization conversion element 21, and the light distribution control plate 16b are the same as described above, but the arrangement directions are different.

The light guide body 17 has a structure in which an incident portion 176 (including an incident surface s6) and a reflecting portion 177 (including a reflecting surface s7) are further added to the incident side. The shape of the portion on the left side of the broken line 511 of the light guide 17 in the Y direction is substantially a triangular prism shape, extending in the X direction, and the YZ cross section is a substantially triangular shape. The incident surface s6 of the incident portion 176 is substantially arranged on a horizontal plane (XY plane). The reflection surface s7 of the reflection portion 177 is a slope having a predetermined angle with respect to the horizontal plane. The reflective surface s7 of the reflective portion 177 may be formed as a repetition of the reflective surface and the connecting surface like the reflective portion 173 on the right side, and may be not limited to this and may be composed of a reflective film or the like.

The optical axis a51 from the LED element 14 or the like is incident on the point p51 of the incident surface s6 after passing through the orientation control plate 16b. The optical axis a56 is reflected at the point p52 of the reflecting surface s7 of the reflecting portion 177, and becomes the optical axis a52 substantially traveling to the right in the Y direction. The optical axis a52 is reflected by the point p3 of the reflecting surface s3 of the reflecting portion 173 and is substantially upward with the optical axis a2 (a21, a22, a23, etc.) in the Z direction, similarly to the above-mentioned optical axis a1. Become.

In the configuration of the fifth modification, the incident portion 176 and the reflection portion 177 of the light guide body 17 are used to arrange the parts such as the light source unit 301 in the Z direction. In comparison, the dimensions in the Y direction (depth direction) can be kept relatively small. This configuration is suitable, for example, when the depth direction of the arrangement space of the dashboard of the vehicle is limited. In the configuration of the fifth modification, the incident surface s6 of the incident portion 176 is a flat surface, but the present invention is not limited to this, and a free curved surface shape for realizing predetermined light distribution control characteristics may be used.

[2-27: 6th modification]
As the light source device 10 of the sixth modification of the second embodiment, the incident surface s1 of the incident portion 171 of the light guide body 17, the emission surface s3 of the emission portion 173, or the reflection surface s2 of the reflection portion 172 is formed on the above-mentioned FIG. Similarly, a texture constituting the functional scattering surface may be provided. For example, the texture as shown in FIG. 22 may be provided on the reflecting surface s2 of the reflecting portion 172 of the light guide body 17 of the above-described second embodiment or each modification. The spatial frequency component of the surface roughness of the functional scattering surface is, for example, 10 nm or less in a high frequency region of 100 / mm or more.

In FIG. 22A, the first example of the texture of the target surface (reflection surface s2) is schematically shown. In FIG. 22B, a second example of the texture of the target surface is schematically shown. In the texture of (a), the boundaries between the plurality of reflecting surfaces and the connecting surfaces are arranged and formed in a straight line. The extending direction of the straight line corresponds to the X direction in which a plurality of LED elements 14 and the like are arranged. With such a texture, light distribution control such as light diffusion is performed in the direction in which the plurality of boundaries are arranged (the direction of the stepped slope; the Y direction on the corresponding exit surface s3). In the texture of (b), the boundaries between the plurality of reflecting surfaces and the connecting surfaces are arranged and formed in a curved shape. This curved shape is formed, for example, corresponding to a position where a plurality of LED elements 14 and collimator elements 15A are arranged. This enables more precise light distribution control.

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. It is possible to add or delete components of the embodiment, separate or merge, replace, combine, and the like.

1 ... head-up display (HUD) device, 3 ... windshield, 4 ... display area, 5 ... eyes, 6 ... line of sight, 7 ... imaginary image, 10 ... light source device, 12 ... LED board, 13 ... heat sink, 14 ... LED element , 15 ... LED collimeter, 16b ... orientation control plate, 17 ... light guide, 18b ... diffuser, 21 ... polarization conversion element, 30 ... image display device, 41, 42 ... reflection mirror, 43 ... refraction element, 50 ... liquid crystal Display element, 80 ... housing, 81 ... opening, 171 ... incident part, 172 ... reflecting part, 173 ... emitting part.

Claims (5)

A head-up display device that projects video light onto the display area of a vehicle's windshield or combiner and provides a virtual image to the driver by reflected light.
A light source device that generates and emits illumination light, and an image display device that includes a display element that generates and emits the image light based on the illumination light.
The windshield or the combiner is provided with an adjusting optical system including an optical element for guiding the image light to the display area of the combiner while reflecting the image light.
The light source device includes a light source unit including a plurality of semiconductor light source elements that generate light, a collimator including a collimator element, and a light guide body arranged on the exit side of the collimator.
The adjusting optical system has, as the optical element, a refracting element that refracts the image light from the display element, and one or more reflection mirrors that reflect the refracted light.
The light guide body is reflected by an incident portion having an incident surface on which light on the light emitting axis from the semiconductor light source element is incident , a reflecting portion that reflects light incident from the incident portion, and a reflecting portion. A free curved surface shape for realizing a predetermined light distribution control is provided on at least one of the incident surface and the emitting surface, including an emitting portion having an emitting surface for emitting light.
The reflecting portion has a plurality of reflecting surfaces and a plurality of connecting surfaces connected to the plurality of reflecting surfaces, and each reflecting surface and each connecting surface are alternately and repeatedly formed.
Moreover, the refraction element of the adjustment optical system is arranged on the reflection mirror side with respect to the display element, and the light guide body is arranged on the light source portion side with respect to the display element .
Head-up display device. In the head-up display device according to claim 1,
The free curved surface shape formed on the light guide and the refracting element of the adjusting optical system expand the emitted light with respect to the incident light.
Head-up display device. In the head-up display device according to claim 2,
The plurality of the semiconductor light source elements and the collimator elements are arranged in a first direction orthogonal to the emission axis.
The light source unit, the collimator, and the light guide body are arranged in a second direction corresponding to the light emitting axis.
The light guide has a pillar shape extending in the first direction, and reflects light in the second direction incident from the incident surface in the first direction and a third direction orthogonal to the second direction. The light guide body includes the reflecting portion having the plurality of reflecting surfaces to be emitted from the emitting surface, and the light guide body has one side of the emitting surface and one of the reflecting portions on the opposite side to the incident surface. It has a parietal region with a parietal surface in contact with the sides, and the exit surface has a predetermined angle with respect to the second direction.
Head-up display device. In the head-up display device according to claim 2,
A head-up display device in which the normal direction of the display surface of the display element forms an angle of 10 ° or more with respect to the direction of the optical axis of the light emitted from the light source device. In the head-up display device according to claim 2,
A head-up display device in which the normal direction of each point of the refracting element forms an angle of 10 ° or more with respect to an image ray incident on each point of the refracting element.

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