JP2019003081A - Light source device, and head-up display device - Google Patents

Abstract

To provide a light source device that is downsized, lightweight, high in light usage efficiency, and is modularized to be easily available as a planar light source.SOLUTION: A light source device 10 comprises: a light source unit that includes a plurality of LED elements 14; an LED collimator 15 that includes each of a plurality of collimator elements arranged on a light emission axis of each of the plurality of LED elements 14; and a light guiding body 17 that is arranged on a light emission side of the LED collimator 15. The light guiding body 17 includes: an incidence section 171 that has an incidence surface making light on the light emission axis from the LED element 14 incident; an emission section 173 that has an exit surface through which the light exits, and has a free curved surface shape for achieving prescribed light distribution control on at least one of the incidence surface and the emission surface.SELECTED DRAWING: Figure 30

Description

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

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

  Conventionally, for example, according to Japanese Unexamined Patent Application Publication No. 2016-33668 (Patent Document 1), a light source device for a projector (projection display device) is a semiconductor light source device having a simple configuration, and a semiconductor light emitting element is 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-described conventional technology (Patent Document 1), mainly by efficiently cooling the semiconductor light emitting element, the element is prevented from short-circuiting and not functioning, A semiconductor element light source device that emits light efficiently and brightly is provided. In addition, the light emitted from the element is condensed using one or a plurality of lenses provided to face the element. Therefore, in the prior art, it is possible to improve the light emission efficiency by the LED which is a semiconductor light source. However, it is difficult to sufficiently collect and use the emitted light. In particular, in a projector that requires a high light emission performance, and further in a HUD device, a headlamp device for a vehicle, and the like, the light use efficiency characteristics. However, the uniform illumination characteristics are still insufficient, and there is room for various improvements.

  Accordingly, an object of the present invention is to provide a light source device that is small 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 has the following configuration. A light source device according to an embodiment includes a light source unit including a plurality of semiconductor light source elements that generate light, and a collimator including a plurality of collimator elements disposed on the light emission axis of each of the plurality of semiconductor light source elements. A light guide disposed on the output side of the collimator, wherein the light guide has an incident portion on which light on the light-emitting axis from the semiconductor light source element is incident, and the light And an exit part having an exit surface for exiting, and at least one of the entrance surface and the exit surface has a free-form surface shape for realizing predetermined light distribution control.

  According to a typical embodiment of the present invention, a light source device that is small and lightweight and has high utilization efficiency of emitted light can be provided.

1 is an exploded perspective view showing an overall overview of a head-up display device including a video display device as an example to which a light source device according to an example (Embodiment 1) of the present invention is applied. It is an expansion | deployment perspective view which shows the external appearance of the internal structure of a video display apparatus. It is a perspective view which shows an example of the internal structure of a light source device. It is a partially expanded sectional view which shows the structure and operation | movement of the collimator and polarization conversion element which comprise a light source device. It is a partially expanded sectional view which shows the comparative example of a structure of a collimator and a polarization converting 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 | combination diffusion block of a light source device, and the partially expanded sectional view which expanded the part. It is the whole perspective view which shows the detail of the light guide which comprises a light source device, its sectional drawing, and a partially expanded sectional view which shows the detail of a cross section. It is a schematic diagram which expands and shows a reflective surface and a connection surface for description of a light guide. It is the upper surface and side view which expand and show a reflective surface and a connection surface for description of a light guide. It is a side view which shows the comparative example of a light guide. It is a side view which shows the modification of a light guide. It is a side view which shows the other modification of a light guide. It is a side view which shows the other modification of a light guide. It is a side view which shows the modification of the light guide using a functional scattering surface. It is a figure containing 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 a process of a light guide. It is a whole external appearance perspective view of the video display apparatus which shows the other example of the video display apparatus to which the light source device is applied. It is the upper surface and side view which show the modification of the larger light guide for liquid crystal display devices. It is a side view which shows the modification of the light guide of the said FIG. It is a top view which shows the specific example of the texture formed in the reflective surface of a light guide. It is a whole side view which shows an example of a structure of the larger sized light source device which combined the light guide. It is a whole side view which shows an example of a structure of the light source device which consists of a light guide provided with the several light-incidence part. It is the upper surface and side view which show an example of the structure which formed the light guide with the polarization conversion element. It is a figure which shows schematic structure at the time of seeing the driver's seat vicinity of the vehicle carrying the HUD apparatus comprised including the light source device and video display apparatus of Embodiment 2 of this invention from the side. It is a figure which shows the functional block structure of the said HUD apparatus. It is explanatory drawing which shows the structure outline | summary in the HUD apparatus of a comparative example, a behavior, subject, etc. in case external light injects. It is explanatory drawing which shows the structure outline | summary in the HUD apparatus of Embodiment 2, a behavior in case external light injects, etc. FIG. It is a figure which shows the structure outline | summary of the said video display apparatus, an adjustment optical system, etc. FIG. It is a perspective view which shows the external appearance of the said video display apparatus. It is a perspective view which shows one Example of the internal structure of the said light source device. It is a partially expanded sectional view which shows the structure of a light source part of the said light source device, LED collimator, a polarization conversion element, etc., 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 example of arrangement configuration of several LED element etc. with respect to the said polarization conversion element. It is a figure which shows the example of arrangement | positioning structure of several LED element etc. of the said light source device. It is a figure which shows the structure of the comparative example with respect to the example of arrangement structures, such as a some LED element of the said light source device. It is the top view and side view which show the 1st Example of the several light source element (when N = 5) of the light source device of Embodiment 2. It is the top view and side view which show the 2nd Example of the several light source element (when N = 6) of the light source device of Embodiment 2. It is the perspective view and side view which show the whole detailed structure of the light guide of the said light source device. It is a side view which shows the detail of the reflection part of the said light guide. 6 is a cross-sectional view showing a configuration of orientation control in the light source device of Embodiment 2. FIG. It is a figure which shows the structure of the light distribution control board of the said light source device. FIG. 10 is an explanatory diagram illustrating a free-form surface expression and coefficients in the light source device of the second embodiment. It is sectional drawing which shows schematic structures, such as a light guide in the light source device and video display apparatus of the 1st modification of Embodiment 2. FIG. It is sectional drawing which shows schematic structures, such as a light guide body in the light source device and video display apparatus of the 2nd modification of Embodiment 2. It is the perspective view and partial sectional view which show the structure of the light source device and video display apparatus of the 3rd modification of Embodiment 2. It is a perspective view which shows the whole light guide in a 3rd modification. It is explanatory drawing which shows the formula and coefficient of the free-form surface of the said light guide. It is a perspective view which shows the structure of the light source device and video display apparatus of the 4th modification of Embodiment 2. It is a perspective view which shows the structure of the light source device and video display apparatus of the 5th modification of Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted. In addition, parts described with reference numerals in certain drawings may be referred to with the same reference numerals without being illustrated again in the description of other drawings.

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

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

  In the HUD device 1 having such a configuration, it is obvious to those skilled in the art that 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 driving unit. Let's go. Further, the display position of the virtual image seen by the driver may be adjusted in the vertical direction by adjusting the position of the image projected onto the windshield by adjusting the angle of the concave mirror 141. In addition, the content displayed as a virtual image is not specifically limited, For example, the vehicle information, navigation information, the image | video of the front scenery image | photographed with the camera image (a monitoring camera, an around viewer, etc.) which is not illustrated can be displayed suitably.

[1-2: Video display device]
Next, the video display device 30 described above will be described in detail below with reference to FIG. The video display device 30 is configured by accommodating, for example, an LED element, a collimator, a synthetic diffusion block, a light guide, and the like, which will be described in detail later, inside a light source device case 11 formed of plastic or the like. Further, a liquid crystal display element (LCD) 50 is attached to the upper surface of the video display device 30, and an LED substrate 12 mounted with an LED element as a semiconductor light source and its control circuit is attached to one side surface thereof. ing. Furthermore, a heat sink (radiation 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.

  In the video display device 30 described above, 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 And a flexible wiring substrate (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, the embodiment of the present invention that constitutes the HUD device 1 is incorporated in a narrow space called a dashboard of a vehicle. For the video display device 30 including such a light source device, it is particularly preferable that the video display device 30 is small in size and highly efficient by modularization and can be suitably used.

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

  Although the details will be described later on the light output side of the LED collimator 15, a polarizing 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 is provided. Further, a rectangular composite diffusion block 16 is provided on the exit 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 function of the LED collimator 15, enters the polarization conversion element 21, and is converted into desired polarization light by the polarization conversion element 21, The light enters the composite diffusion block 16.

  Further, as shown in FIG. 3, a light guide body 17 having a substantially triangular cross section is provided on the exit surface side of the composite diffusion block 16 via a first diffusion plate 18a. The second diffusion plate 18b is attached to the upper surface. Thereby, the horizontal light of the LED collimator 15 is reflected upward in the drawing by the action of the light guide 17 and guided to the incident surface of the liquid crystal display element 50. At that time, the first diffusion plate 18a and the second diffusion plate 18b make the strength uniform.

  Subsequently, main parts constituting the light source device according to the above-described embodiment of the present invention will be described below including 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 (14 a, 14 b) that is one or a plurality of semiconductor light emitting elements formed on the LED substrate 12, and the LED element. The LED collimator 15 is arranged to face the 14 light emitting surfaces. Note that the LED collimator 15 is formed of a resin having excellent heat resistance such as polycarbonate and a light-transmitting resin, for example, as shown in FIG. It is formed so as to surround the periphery. More specifically, the LED collimator 15 has a conical outer peripheral surface 156 obtained by rotating a substantially parabolic cross section, and a concave portion 153 having a predetermined curved surface at the top of the light incident side. Is formed, and the LED element 14 (14a, 14b) is disposed at a substantially central portion thereof. In addition, the paraboloid (reflector part) which forms the conical outer peripheral surface 156 of the LED collimator 15 is emitted in the peripheral direction from the LED element 14 (14a, 14b) together with the curved surface of the recessed part 153, and is in the recessed part 153. Light that enters the interior of the LED collimator 15 through the air is set to be incident within a range of angles that are totally reflected on the paraboloid. As described above, by utilizing the total reflection on the parabolic surface, a process such as forming a metal reflection film on the outer peripheral surface 156 of the LED collimator 15 is not required, so that the device is manufactured at a lower cost. It becomes possible.

  In addition, an incident surface (lens surface) 157 having a predetermined curved surface is formed at the central portion of the concave portion 153 of the LED collimator 15, and a convex portion (lens) formed on the opposing surface (exit surface) 154. (Surface) 158 and a so-called convex lens having a condensing function. The convex portion 158 may be formed as a flat lens surface or a concave lens surface recessed inward. That is, the LED collimator 15 has a function of a condensing lens that collects light emitted from the LED collimator 15 on the exit surface side at the center of the conical outer shape, and also on the outer peripheral surface 156 (reflector portion) thereof. Similarly, the light emitted from the LED element 14 (14a, 14b) in the peripheral direction is condensed and guided to the emission surface side.

  As shown in FIG. 4, the LED board 12 is arranged such that the LED elements 14 (14 a, 14 b) on the surface of the LED collimator 15 are positioned at the center of the recess 153. Arranged and fixed.

  According to such a configuration, among the light emitted from the LED elements 14 (14a, 14b), in particular, the light emitted from the central portion thereof toward the outgoing optical axis (right direction in the drawing) is the LED collimator described above. 15, as indicated by an arrow in the drawing, the light is condensed by two convex lens surfaces 157 and 158 forming the outer shape of the LED collimator 15 to become parallel light, and is emitted from other portions toward the peripheral direction. Are reflected by the parabolic surface forming the conical outer peripheral surface (reflector portion) 156 of the LED collimator 15, and are similarly condensed to become parallel light. In other words, according to the LED collimator 15 having a convex lens at the center and a paraboloid at the periphery thereof, almost all of the light generated by the LED elements 14 (14a, 14b) is converted into parallel light. And the utilization efficiency of the generated light can be improved.

  Further, in this embodiment, a polarization conversion element 21 made of an optical member such as a polarization beam splitter and a phase plate is provided on the light emission side of the LED collimator 15, and these elements are also shown in the drawing. As is apparent, the LED collimator 15 is arranged symmetrically with respect to the central axis (see the dashed line in the drawing). Further, a rectangular composite diffusion block 16 is provided on the exit side of the polarization conversion element 21. That is, the light emitted from the LED element 14 a or the LED element 14 b is converted into parallel light by the action of the LED collimator 15 and enters the composite diffusion block 16.

[1-5: Comparative example]
Thus, according to this configuration, as is clear from the comparison with the comparative example of FIG. 5, the thickness is reduced and the cost is reduced by reducing the amount of material used, thereby reducing the size of the light source device. to enable. The thinning of the polarization conversion element prevents an increase in the optical path length difference between the light beam reflected by the PBS film and the transmitted light beam, so that the difference in the light beam shape due to the optical path length difference is unlikely to occur. In a system using a light source and an LED collimator, it is effective in eliminating nonuniformity in luminance distribution caused by a difference in light beam shape.

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

  In the present embodiment, the rectangular composite diffusion block 16 is provided on the light emission side of the LED collimator 15, but the polarization conversion element 21 described above 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 combined diffusion block 16.

  Furthermore, as shown in FIG. 6 as an example, a light guide 17 having a substantially triangular cross section is provided on the exit surface side of the composite diffusion block 16 via a first diffusion plate 18a. A second diffusion plate 18b is attached to the upper surface. Thereby, the horizontal light of the LED collimator 15 is reflected upward in the drawing by the action of the light guide 17 and guided to the incident surface of the liquid crystal display element 50. In this case, the strength is made uniform by the first diffusion plate 18a and the second diffusion plate 18b as in the above example.

[1-7: Composite diffusion block]
Next, the composite diffusion block 16, which is another component of the video display device 30, will be described with reference to FIG. 7A shows a side view of the synthetic diffusion block 16, and FIG. 7B shows a partially enlarged cross-sectional view in which a part of the synthetic diffusion block 16 is enlarged.

  In the synthetic diffusion block 16 formed of a translucent resin such as acrylic, as is clear from FIG. 7, a large number of textures 161 having a substantially triangular cross section are formed at a pitch S on the exit surface. By the action of the texture 161, the light emitted from the LED collimator 15 is diffused in the vertical direction of the light guide light incident part (surface) 171 of the light guide 17 described below. Even if the LED collimators 15 are discretely arranged due to the interaction between the substantially triangular texture 161 and the diffusion plates 18a and 18b described below, the light guide light emitting portion 173 of the light guide 17 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 viewed by the driver can adjust the angle of the concave mirror 141 as described above. Since the confirmation is based on binocular vision, it is desirable that the area in which the virtual image can be visually recognized is wider in the left-right direction than in the vertical direction. In order to realize the above configuration, it is effective to make the direction corresponding to the left-right direction of the virtual image of the light distribution angle of the light source device wider than the front-rear direction. In this configuration, the area in which the virtual image can be recognized is widened in the left-right direction by setting the direction in which the orientation angle is widened as the horizontal direction of the virtual image display by being diffused by the texture 161 of the synthetic diffusion block.

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

[1-8: Light guide]
Next, details of the light guide 17 constituting the video 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 the incident surface as parallel light from the above-described light source device and guiding it in a desired direction, and extracting it as planar light having a desired area. Have

  8A is a perspective view showing the entire light guide 17, FIG. 8B is a cross section thereof, and FIGS. 8C and 8D show details of the cross section. FIG. The light guide 17 is a member formed in a substantially triangular cross-section (FIG. 8B) using, for example, a translucent resin such as acrylic, and as is apparent from FIG. 8A. , A light guide light incident part (surface) 171 facing the exit surface of the composite diffusion block 16 via the first diffusion plate 18a, a light guide light reflecting part (surface) 172 forming a slope, A light guide light emitting portion (surface) 173 facing the liquid crystal display panel 52 of the liquid crystal display element 50 through two diffusion plates 18b. In some cases, they may be referred to as an incident portion 171 (incident surface), a reflecting portion 172 (reflecting surface), an emitting portion 173 (exiting surface), and the like.

  As shown in detail in FIGS. 8C and 8D, which are partially enlarged views, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately sawtoothed on the reflecting portion 172 of the light guide 17. It is formed in a shape. The reflecting surface 172a (in the drawing, a line segment rising to the right) 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 (in the drawing, a downward-sloping line segment) 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 a reflection surface elevation angle, and the angle βn (β1, β2, β3, β4...) Is connected to the reflection surface 172a. A relative angle to 172b is formed, and as an example, it is set to 90 degrees or more (however, 180 degrees or less). In this example, the angles β1 = β2 = β3 = β4 =... = Β22 =.

[1-9: Light guide (2)]
9 and 10 are schematic views in which the sizes of the reflecting surface 172a and the connecting surface 172b are relatively enlarged with respect to the light guide 17 for the sake of explanation. In the incident portion 171 of the light guide 17, the main light beam is deflected by an angle δ in the direction in which the incident angle becomes larger with respect to the reflecting surface 172a ((b) of FIG. 10). That is, the incident portion 171 is formed in a convex shape that is curved toward the light source side. According to this, the parallel light from the exit surface of the synthetic diffusion block 16 is diffused and incident through the first diffusion plate 18a, and is slightly bent upward by the incident portion 171 as is apparent from the drawing. While reaching (deflection), the reflection part 172 is reached (compared with the example of FIG. 11).

  The reflecting portion 172 has a plurality of reflecting surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth shape, and the diffused light is totally reflected on each reflecting surface 172a and is directed upward. Enters the liquid crystal display panel 52 as parallel diffused light via the emitting portion 173 and the second diffusion plate 18b. Therefore, the angle αn (α1, α2,...) That is the reflection surface elevation angle is set so that each of the reflection surfaces 172a has an angle greater than the critical angle with respect to the diffused light, while the reflection surface 172a. The angle βn (β1, β2,...), Which is a relative angle between the contact surface 172b and the connecting surface 172b, is a constant angle as described above, and the reason for this will be described later. 90 °).

[1-10: Comparative example]
With the above-described configuration, each reflecting surface 172a is configured to always have an angle greater than the critical angle with respect to the diffused light. Therefore, even if a reflecting film such as a metal is not formed on the reflecting portion 172, It is possible to realize a light source device including a light guide that can be reflected and can be led in a desired direction and extracted as planar light having a desired area at a low cost. 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 17, a part of the diffused light has a critical angle with respect to the reflection surface 172a. As a result, the sufficient reflectance cannot be ensured, so that a light source device with good characteristics (bright), that is, a video display device cannot be realized.

  However, according to the shape of the reflection portion 172 of the light guide 17 described above, the total reflection condition of the main light can be satisfied, and it is not necessary to provide a reflection film such as aluminum on the reflection portion 172, and the light is efficiently reflected. Therefore, a bright light source can be realized at a lower cost without the need for an aluminum thin film vapor deposition operation accompanied by an increase in manufacturing cost. In addition, the angle βn, which is each relative angle, was set to an angle at which the connecting surface 172b becomes a shadow with respect to the light that the main light beam L30 diffused by the synthetic diffusion block 16 and the diffusion plate 18a. Thereby, by suppressing the incidence of unnecessary light on the connecting surface 172b, reflection of unnecessary light can be reduced, and a light source device with good characteristics can be realized.

  Further, according to the light guide 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,...) By appropriately setting the ratio, the length of the emitting portion 173 in the optical axis direction can be freely changed. Therefore, the size (surface size) of the emitting portion 173 with respect to the incident portion 171 is set to the liquid crystal display. It is possible to realize a light source device that can be appropriately changed to a necessary size (surface size) that is suitable for a device such as the panel 52. This also means that the emission part 173 can be formed in a desired shape without depending on the arrangement shape of the LED elements 14 (14a, 14b) constituting the light source. A planar light source having a shape is obtained. Furthermore, 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 downsizing of the entire apparatus.

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

  Further, in FIG. 13, as another modified example, the incident portion 171 of the light guide 17 is a vertical plane, and the LED collimator 15 is slightly tilted so that the incident light is slightly bent upward. A configuration for deflecting is shown. That is, the same effects as described above can be obtained by these modified examples.

[1-12: Modification]
Further, as shown in FIG. 14, the connecting surface 172b constituting the reflecting portion 172 is appropriately set (in this example, light is not reflected by a part of the reflecting surface 172a in the central portion). For example, in the emission part 173 of the light guide 17, the ratio (Lr / Lc) of the reflecting surface 172a and the connecting surface 172b can be greatly changed depending on the location. Thereby, in the example of illustration, a mode that the light radiate | emitted from the output part 173 of the light guide 17 is divided into right and left in the direction of an optical axis is shown. 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 ratio (Lr / Lc), it is possible to partially increase or decrease the reflected light.

[1-13: Modification]
In addition, in the light guide 17 described above, the functional scattering surface described below is provided and formed on at least one of the incident portion 171 and the emission portion 173, as shown in FIG. Either or both of the diffusion plates 18a and 18b also shown in FIG. 6 can be omitted.

  This functional scattering surface is intended to reduce unnecessary divergent light components by reducing the surface roughness of high spatial frequency components (fine components). 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 drawing, the solid line represents the surface roughness spatial frequency component when measured in the direction perpendicular to the incident surface or the exit surface of the light guide in FIG. 15, and the broken line represents the incident surface of the light guide in FIG. The surface roughness spatial frequency component when measured in the direction parallel to the drawing of the exit surface is shown.

  The surface roughness spatial frequency distribution of the normal scattering surface is a distribution along the reciprocal (1 / f) of the spatial frequency, as shown in FIG. On the other hand, as shown in FIG. 16A, the spatial frequency distribution of the more preferable surface roughness has a low value in a low frequency with a spatial frequency of 10 / mm or less and a high frequency region with a frequency of 100 / mm or more. In addition, since the low frequency component of the surface roughness spatial frequency is small and the medium frequency component is moderate, a light source with little scattering unevenness can be realized. In addition, since the high-frequency component of the surface roughness spatial frequency is small, the scattering angle of the scattered light is not increased, and unnecessary light components are reduced, so that a light source having a bright and uniform luminance distribution can be realized. In order to realize such characteristics, the functional scattering surface further has a visible frequency range (wavelength of 400 nm or more) when the spatial frequency component in a high frequency region of 100 / mm or more is set to 10 nm or less. Experiments have confirmed that unnecessary scattering components can be prevented. On the other hand, as shown in FIG. 16B, the normal scattering surface scatters light out of the direction that can be used as the light source, and thus 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. As described above, the HUD device is desired to have a wide horizontal area with respect to the vertical direction in the area where the virtual image can be visually recognized. Therefore, the orientation angle of the light source device is set so that the corresponding direction is wide. It was adjusted. Specifically, the spatial frequency distribution of the surface roughness measured in the direction perpendicular to the drawing of the entrance surface and the exit surface of the light guide shown in FIG. 15 is the distribution indicated by the solid line in FIG. The spatial frequency distribution of the surface roughness measured in the direction along the drawing orthogonal to it was a distribution with a relatively smaller high-frequency component than the solid line, as indicated by the broken line in the drawing.

  By adopting the functional scattering surface described above, the degree of freedom of control of light incident / exit on the entrance surface and exit surface of the light guide 17 is increased, and uneven brightness of light from the light source device is reduced. This makes it possible to perform fine control according to the characteristics of the optical system apparatus (in this example, the liquid crystal display element 50 as an example) disposed on the downstream side, and is advantageous in reducing the cost of the apparatus.

  Further, as shown in FIG. 15, the incident surface of the light guide 17 has an upper end portion with respect to the central portion 171c in a cross section in a plane parallel to the incident light and the emitted light to the light guide. The curvature of 171a and the lower end part 171b was made large. This is effective when the LED element 14 having a relatively large light emitting portion size 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 as light rays L30c, L30a, and L30b indicated by solid lines, but the light emitted from the upper and lower ends of the LED element 14 Is a diffused light instead of a parallel light like the light rays L30d and L30e indicated by the alternate long and short dash lines. As indicated by 171b, it is necessary to increase the curvature with respect to the central portion 171c. By adopting the above configuration, a light source device with good characteristics can be realized even when a relatively large LED is used.

[1-14: Method for manufacturing light guide]
Further, as described above, the angle β1 = β2 = β3 = β4... Βn ≧ 90 ° is set, but this is because the light guide 17 is produced by injection molding as shown in FIG. This is because in the machining 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 an end mill whose relative angle between the bottom surface and the side surface is β. Further, since the reflecting surface 178a and the connecting surface 178b can be processed with a relatively thick tool, the processing time can be greatly shortened, and the processing cost can be significantly reduced. In addition, the boundary edge between the reflection surface 178a and the connecting surface 178b can be processed with high accuracy, and the light guide characteristics of the light guide 17 can be improved.

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

[1-16: Light source device (another embodiment)]
Furthermore, still another embodiment of the light source device according to the embodiment of the present invention described above will be 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 columns, 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 thick, so that the cooling time in the molding die is increased, the molding tact is lengthened, and the cost is increased. In order to prevent this, a part (upper part of the drawing) of the incident part 171 is deleted.

  FIG. 21 shows a larger light source device for a liquid crystal display device in which the arrangement of the LED elements 14 that are solid light sources is 3 × 2 rows, as in the light source device of the above embodiment. In this example, a part of the incident portion 171 is deleted, and the tip portion (right side portion of the drawing) of the light guide body 17 is thickened to achieve a uniform cooling rate during molding. Can be formed easily. In this example, the light guide 17 is configured so that the main light beam is incident on the liquid crystal display panel with an incident angle inclined by a predetermined angle η by making the tip portion thick. 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 liquid crystal display panels that are commercially available 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 depends on the characteristics. Is incident at an angle η = 5 ° to 15 °.

[1-17: Light guide texture]
Further, FIG. 22 is a top view showing a specific example of the above-described texture formed on the reflection surface of the light guide 17 shown in FIG. 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. 22A, and in FIG. 22B, for example, an LED element as a light source. 14 (14a, 14b) are shown as other examples arranged and formed in a curved shape according to the necessity, such as being arranged separated and distributed from each other.

[1-18: Video Display Device (Other Examples)]
The example of the light source device according to the embodiment of the present invention, in particular, the light source device applied to the HUD device 1 has been described above. Hereinafter, an example including another configuration of the light source device will be described. .

  In FIG. 23, a plurality of (two in this example) light source devices including the above-described LED elements 14 (14a, 14b), the light guide 17 and the like are combined so that their emission parts 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 realize an image display device including more types of surface sizes and light emission units 173.

[1-19: Video display device (another embodiment)]
FIG. 24 further shows a light source device including a light guide body 17 ′ having a plurality of (two in this example) incident portions 171A and 171B. As is clear from the drawing, the light guide device is also shown in FIG. Incident portions 171A and 171B for receiving light from a light source including the LED elements 14 (14a and 14b) and the LED collimator 15 are formed on both side surfaces of the body 17 ′. The incident portions 171A and 171B are formed. The parallel light incident from the light is refracted and guided to the reflecting portion 172 formed at the bottom of the light guide 17 ′ in this example. On the surface of the reflection portion 172, irregularities having a wavy cross section are formed, and a reflection 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 indicated by an arrow in the drawing and directed upward of the light guide body 17 ′. The light is emitted toward a device such as the liquid crystal display panel 52.

  According to the light source device having such a configuration, even if the liquid crystal display device for irradiating light is increased in size, it is possible to realize a light source device that can relatively easily respond, that is, whose output surface is increased in size. As is clear from the above, since the light source device can be realized by the relatively thin light guide 17 ', the device can be made thinner. Further, the thickness of the light guide 17 'is almost uniform, and its moldability is good.

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

[1-20: Light source device (another embodiment)]
Further, as shown in FIG. 25, it is also possible to configure the light guide body 17 ″ disposed behind the combined diffusion block 16 with a polarization conversion element 21 ′. In this configuration, it is also apparent from the drawings. As described above, the triangular prismatic translucent member 211 ′ and the parallelogram prism translucent member 212 ′ constituting the polarization conversion element 21 ′ are combined, and the LED element 14 (14a, 14a, 14b) reflects the S-polarized wave (see symbol (x) in the figure) of the incident light emitted from the LED collimator 15 and converted into parallel light, while P-polarized light (see the up and down arrows in the figure) ) Is transmitted, and a 1 / 2λ phase plate 213 is formed on the upper surface of the translucent member 212 ′ having a parallelogram prism shape, and a reflective film 212 is formed on the side surface thereof. Each is formed.

  According to the above-described configuration, as is apparent from the drawing, the incident light emitted from the LED element 14 and converted into parallel light by the LED collimator 15 functions as the polarization conversion element 21 ′ constituting the light guide 17 ″. Is polarized to S-polarized light and emitted upward from the upper surface of the element. That is, in the above configuration, the light guide body 17 ″ is configured by the polarization conversion element 21 ′, and thereby the device It is possible to achieve a significant reduction in size and a significant reduction in the manufacturing cost of the device.

(Embodiment 2)
A light source device or the like according to another embodiment (referred to as Embodiment 2) of the present invention will be described with reference to FIGS. The light source device of the second embodiment has a specific light guide structure and includes the following configuration points. The light source device of the second embodiment has an arrangement configuration including a unique light guide different from the first embodiment (FIG. 30 and the like described later). This light guide has a free-form surface shape on at least one of the entrance surface and the exit surface. The free curved surface shape realizes predetermined light distribution control characteristics in the light guide. Further, the liquid crystal display element 50 and the refractive element 43 have a predetermined angle so that the axes (normal inclinations) of the liquid crystal display element 50 and the refractive element 43 are inclined with respect 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 refraction angle etc. due to the arrangement angle and surface shape of the entrance surface, the reflection angle etc. of the reflection surface, and the refraction angle etc. due to the arrangement angle of the exit surface and free-form surface shape . The light distribution control characteristic of the light source device according to the second embodiment is configured by a combination of the light distribution control characteristic of the light guide and the light distribution control characteristic of other optical elements of the light source unit and the illumination optical system. The

[2-1: HUD device]
FIG. 26 shows the concept of the vehicle-mounted HUD device 1 configured using the video display device 30 including the light source device 10 according to the second embodiment, from the side of the vicinity of the driver's seat of the vehicle 2 on which the HUD device 1 is mounted. A schematic configuration as seen is shown. A real image that is transmitted through the display area 4 of the windshield 3 in front of the driver's eyes 5 (also referred to as a viewpoint) sitting on the driver's seat or superimposed on the real image by the HUD device 1. A state is shown in which a displayed virtual image 7 (for example, an arrow image) is viewed. In FIG. 26, the X direction, the Y direction, and the Z direction are shown as directions for explanation. The X direction (direction perpendicular to the drawing) corresponds to the first horizontal direction, the left-right direction of the vehicle 2, and the horizontal direction of the display area 4. The Y direction (lateral 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 visual recognition area. The visual recognition area is an area where an image can be visually recognized as viewed from the driver. A display area 4 of the HUD device 1 is formed in the viewing area of the windshield 3. The display area 4 is an area where video 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 a vehicle 2 and is provided as a part of an in-vehicle system, for example. The HUD device 1 is installed on a part of the dashboard of the vehicle 2, for example. The HUD device 1 includes a video display device 30 and an optical system. In the HUD device 1, the components of the video display device 30 and the components of the optical system are arranged and accommodated in an exterior case that is a casing. 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 components of the optical system include reflection mirrors 41 and 42, a refraction element 43, and the like which will be described later.

  The video display device 30 includes a light source device (light source module) 10 and a liquid crystal display element 50 that is a display element. The video display device 30 is a projector that generates and emits video light based on video data and performs projection display on the windshield 3 (or a combiner (not shown) or the like). 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 described in the first embodiment, and generates and emits illumination light for the liquid crystal display element 50.

  The liquid crystal display element 50 generates image light based on the display signal and illumination light from the light source device 10 and emits the image light to an optical system (particularly described as an adjustment optical system). The adjustment optical system includes a refractive 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 the image 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 the refraction element 43, and the windshield 3. Project to a part of the area.

  The refraction element 43 includes a lens that refracts image light. The refraction element 43 may be connected to a drive unit such as a motor for changing the arrangement angle or the like so that the optical axis and the direction of refraction can be adjusted. The reflection mirror 42 is, for example, a plane mirror, and reflects light emitted from the liquid crystal display element 50, for example, roughly in the vertical direction (Z direction) toward the reflection mirror 41 that is generally forward (left in the Y direction). Reflect to. The reflection mirror 41 is, for example, a concave mirror, and reflects image light incident from the Y direction approximately toward the windshield 3 generally above the vertical direction (Z direction). The reflection mirrors 41 and 42 may be connected to a drive unit such as a motor for adjusting the arrangement angle or the like 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 partial area (display area 4) of the windshield 3 and enters the driver's eyes 5. And forms an image on the retina. As a result, the driver visually recognizes the image or image superimposed on the transmitted real image as the virtual image 7 in the display area 4 of the windshield 3 in front of the field of view by viewing the image light.

  The line of sight 6 when viewing the virtual image 7 from the optical axis of the image light or the driver's eyes 5 is indicated by a one-dot chain line. In addition, an optical axis of external light such as sunlight that enters the windshield 3 and 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 an internal functional block configuration of the HUD device 1 of FIG. The HUD device 1 includes a control unit 1A, a video display device 30, and an adjustment optical system 40. The video display device 30 includes a display control unit 30A, the light source device 10, and a liquid crystal display element 50 that 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 includes the LED element 14 and the like as described in the first embodiment. The illumination optical system 302 includes the LED collimator 15, the polarization conversion element 21, the light guide 17, and the like as described in the first embodiment. 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 adjustment optical system 40 includes a refractive element 43, reflection mirrors 42 and 41, and the like. At least the reflection mirror 43 is connected with 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 on the display region 4 by controlling the display control unit 30A of the video 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 in accordance with 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 the drive control signal. The light generated from the light source unit 301 is condensed and uniformed by the illumination optical system 302 and irradiated onto 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 the display signal and illumination light. In the illumination optical system 302, orientation control with predetermined characteristics for generating illumination light suitable for the liquid crystal display element 50 and the HUD device 1 is performed by optical components.

  In addition, as a display element, not only the liquid crystal display element 50 but another kind of element is applicable. In that case, the characteristics including the light distribution control of the adjustment optical system 40 and the light source device 10 are mounted so as to match the characteristics of the display element.

[2-3: Comparative examples, problems, etc.]
FIG. 28 shows a schematic configuration of an HUD device 280 of a 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 component arrangement outline of the HUD device 280 of FIG. 28 is the same as that of FIG. The HUD device 280 of the comparative example has the same components as those of the above-described 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 composite diffusion block 16, a diffusion in order from the front (left in the drawing) to the rear (right in the drawing) in the Y direction. A plate 18a and a light guide 17 are arranged. The light emitting axis of the LED element 14 is the Y direction, and is indicated by the optical axis a1. The light guide 17 has a columnar shape with 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 17 in the Z direction. A reflection mirror 41 is disposed in front of the reflection mirror 42 in the Y direction (left). There is an opening 81 of the housing 80 above the reflection mirror 41 in the Z direction.

  The light emitting axis extending in the Y direction from the light emitting point of the LED element 14 is indicated by an optical axis a1. The optical axis a <b> 1 is converted into the optical axis a <b> 2 in the Z direction by the reflecting portion of the light guide 17. The entrance surface and exit surface of the light guide 17 are flat. The exit surface of the light guide 17 and the diffusion plate 18b are disposed on a horizontal XY plane. In the Z direction, the panel surface of the liquid crystal display element 50 is disposed above the light exit surface of the light guide 17 and the diffusion plate 18b in a state inclined to some extent in the horizontal XY plane. On the optical axis a2, above the liquid crystal display element 50, the refractive element 43 is similarly tilted.

  On the optical axis a <b> 2, the image light that is emitted from the liquid crystal display element 50 enters the point Q <b> 2 of the reflection mirror 42 via the refraction element 43. The optical axis a2 is roughly reflected to the left in the Y direction by the reflection at the point Q2 of the reflection mirror 42, and becomes the optical axis a3. The optical axis a3 is incident on the point Q1 of the reflection mirror 41. The optical axis a3 becomes an optical axis a4 upward in the Z direction by reflection at the point Q1 of the reflecting mirror 41. The optical axis a4 is incident on the point Q3 of the display area 4 of the windshield 3 and reflected, and becomes the optical axis a5 to the right in the Y direction, and enters 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 around the rotation axis in the X direction (in this example, an angle with the horizontal plane as a reference of 0 degree), 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 light guide 17 is used to bend the optical axis in the Y direction and the Z direction as in this comparative example. Components such as the heat sink 13, the LED substrate 12, the LED collimator 15, and the 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. Thereby, it becomes disadvantageous for size reduction of the HUD device 1.

  Since the HUD device is installed in a limited space such as a dashboard in a vehicle, for example, a smaller and more efficient device is required. The video display device 30 and the light source device 10 are desirably realized as smaller and more efficient modules so as to be suitable for mounting a HUD device or the like. Further, it is required to generate a suitable image light for a virtual image while downsizing the HUD device. In order to generate suitable image light, suitable illumination light from the light source device 10 is required. In addition, 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, and uniformity of in-plane light intensity distribution. It is also required to reduce the size of the device while ensuring these characteristics.

  The image light from the image display device 30 is subjected to an action such as refraction, reflection, or enlargement via the adjusting optical system 40, and is projected onto the display area 4 of the windshield 3 so that the eyes of the driver are at a predetermined convergence angle. 5 is incident. From the viewpoint of the driver, a virtual image 7 corresponding to a 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 as HUD image light, it is necessary to sufficiently expand the image light before entering the reflection mirror 41. In particular, in order to achieve a horizontal light convergence angle of 4 ° to 10 °, it is necessary to enlarge the image light to approximately 200 mm or more. For that purpose, measures such as enlarging the emitted light by the light source device 10 and enlarging the emitted light by the refractive element 43 or the reflection mirror 42 of the adjusting optical system 40 are required.

  In the configuration including the optical system of the comparative example of FIG. 28, the optical axis a2 in the Z direction of light emitted from the light source device 10 (light guide 17) and the axes (normal lines) of the liquid crystal display element 50 and the refractive element 43 are used. (Direction) is arranged at a predetermined angle. In such a configuration, there is a problem of influence of external light as follows. In FIG. 28, the optical path when external light enters the HUD device 280 is indicated by the two-dot chain line optical axes b1 to b4 and the like. The optical axes b1 to b4 travel in the reverse direction with respect to the optical path of the image light emission (optical axes a1 to a5). Since the optical axis b2 and the like overlap with the optical axis a4 and the like, they are illustrated with a slight shift.

  When external light enters the HUD device 280, the external light enters the refractive element 43 and the liquid crystal display element 50 through the reflection mirrors 41 and 42 of the adjustment optical system 40. Further, the outside light is reflected by the refracting element 43 and the like, returns in the reverse direction of the optical path, and a part of the outside light goes out of the HUD device 280. Then, the external light may be reflected by the windshield 3 and enter the driver's eyes 5. Accordingly, the driver visually recognizes the virtual image 7 in a state where external light is reflected as noise in the image light of the virtual image 7 in the display area 4. Therefore, the driver may have difficulty in visually recognizing the virtual image 7. That is, the display quality of the virtual image is degraded.

  First, an optical axis b1 of external light from above the vehicle 2 is incident on a point Q3 of the display area 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 external light that has entered the windshield 3 enters the point Q1 of the reflection mirror 41 through 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. The optical axis b4 of the external light reflected at the point Q2 enters the refraction element 43 and the liquid crystal display element 50. The external light reflected by the refracting element 43 and the like returns in the direction opposite to that at the time of incidence as indicated by the optical axes b5, b6, and b7. The outside light exits from the inside of the HUD device 280, is reflected at the point Q3 in the display area 4 of the windshield 3, and enters the driver's eyes 5 as the optical axis b8.

  In the light source device 10 and the adjustment optical system 40 of the HUD device 280, light distribution control for realizing a predetermined convergence angle is necessary for suitable image light for forming the virtual image 7 of the suitable display region 4. For the light distribution control, for example, a configuration as shown in FIG. 28 is adopted. In this configuration, as described above, an external light component that returns to the outside of the HUD device 280 due to reflection of external light that has entered the HUD device 280 (may be described as return external light) occurs. That is, incident external light is excluded by reflection or absorption to some extent by the function of the window shield 3 and the opening 81 of the HUD device 1 by tilting the refractive element 43 and the liquid crystal display element 50 to some extent, but is particularly refracted. Since the surface of the element 43 is concave, part of the reflected light travels back along the incident optical path and cannot be completely eliminated. Therefore, the display quality of the virtual image 7 is deteriorated when the returning external light enters the driver's eyes 5.

  Therefore, the light source device or the like of the second embodiment provides a function that can prevent or reduce 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 according to the second embodiment, the direction of the optical axis with respect to the liquid crystal display element 50 and the refractive element 43 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 that the normal inclination angle of the effective surface (the surface through which the image light is transmitted or reflected) with respect to the optical axes of the illumination light and the image light is at least 10 ° or more. I found out. With this contrivance, the light source device or the like according to the second embodiment realizes predetermined light distribution control characteristics so as to satisfy both generation of suitable image light and prevention of return external light and the like. Illumination light generated based on predetermined light distribution control in the light source device is supplied to the liquid crystal display element. Then, image 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 refractive 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 that of the comparative example. That is, the surface shape of the refracting element 43 does not need to be as steep as the concave surface (curvature) as in the comparative example. Thereby, in the light source device or the like according to the second embodiment, when external light is incident on the HUD device, the external light is adjusted to the adjustment optical system or the liquid crystal display element by tilting the refractive element 43 and the liquid crystal display element 50 to some extent. Even if the light is reflected, the light hardly returns to the outside of the HUD device, that is, almost no return external light is generated. Therefore, it is prevented or reduced that the display quality of the virtual image is deteriorated by the return external light entering the eyes of the driver. That is, in the second embodiment, it is possible to obtain an effect of preventing or reducing the return external light while securing suitable video light, and suppressing a reduction in the visibility of the virtual image due to the influence of the external light.

  In the comparative example, in order to reduce the influence of external light, an optical element or the like is installed such that the adjustment optical system 40 in the HUD device 280 deflects external light and does not reflect the display area 4 (for example, FIG. 28). Thus, when the liquid crystal display element 50 and the refractive element 43 are arranged to be inclined with respect to the horizontal plane), the characteristics of the image light are inevitably affected. Therefore, the characteristics of the light distribution control are devised and controlled by the entire light source device 10, the liquid crystal display element 50, the refraction element 43, and the like so as to ensure a predetermined suitable image light characteristic while reducing the influence of returning external light. There is a need to.

  By adopting the configuration in which the normal inclination angle of the second embodiment is provided, the light reflected by the refracting element 43 or the like in the external light that is incident backward through the optical path of the image light is at least the normal inclination with respect to the incident light. The direction is shifted with an angle (for example, 20 °) that is twice the angle (for example, 10 °). Therefore, it is possible to prevent or reduce the reflected light from coming out of the HUD device 1 (opening 81) and being reflected again by the windshield 3 as external light and entering the driver's eyes 5. However, in order to satisfy such conditions for avoiding external light, the structure of the adjusting optical system 40 such as the refractive element 43 and the reflecting mirrors 41 and 42 is naturally limited.

  Due to the above limitation, a suitable image light (light sufficiently enlarged for the display area 4) cannot be realized only by a measure for expanding the light by the adjusting optical system 40 such as the refractive 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 outgoing light is expanded by the adjustment optical system 40 and a configuration in which illumination light is expanded by the light source device 10. As a result of various examinations, at least one of the entrance surface and the exit surface of the light guide has a free-form surface shape as a configuration capable of simultaneously realizing downsizing, thinning, high efficiency of the light source device and enlargement control of the illumination light. As a result, it was found that the configuration for controlling the orientation was 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 video display device 30 according to the second embodiment with respect to the comparative example of FIG. An optical path and the like when external light is incident on the HUD device 1 are also shown. The light source device 10 and the video display device 30 of the second embodiment have light distribution control characteristics different from those of the comparative example. 29 and the like are schematic configurations, and the mounting size and the like are not limited to those in FIG.

  In FIG. 29, the light source unit 301 includes the LED substrate 12 on which a plurality of LED elements 14 and a control circuit are mounted. A heat sink 13 is provided on the back side of the LED substrate 12. The illumination optical system 302 includes the LED collimator 15 disposed in the Y direction, the polarization conversion element 21, the light guide 17, the diffusion plate 18b disposed in the Z direction, and the like. The LED collimator 15 condenses the light of the optical axis a1 in the Y direction from the LED element 14 and converts it into parallel light. The polarization conversion element 21 optically converts and emits the incident light from the LED collimator 15 so as to polarize the light beam direction and widen the light beam width. The light guide 17 guides the direction of the optical axis a1 in the Y direction from the LED element 14 so as to be changed to 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 17 has a substantially trapezoidal columnar cross section, and converts the direction of light from the Y direction (horizontal direction) to the Z direction (vertical direction). Specifically, the light emitted from the light guide 17 is an optical axis inclined at a predetermined angle with respect to the Z direction through the free-form surface shape of the output surface of the light guide 17 (a slope having a predetermined angle with respect to the horizontal plane). It becomes.

  The optical axes of the illumination light and the image light and the axes (normal inclination angles) 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 emitted light from the light guide body 17, is incident on the liquid crystal display element 50 arranged at a predetermined angle on the horizontal plane (XY plane), and video light is generated. The image light from the liquid crystal display element 50 has an optical axis inclined at a predetermined angle with respect to the Z direction. The image light is incident on the refraction 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 enters the point Q2 of the reflecting mirror 42 and is reflected. The reflected light on the optical axis a3 is incident on the point Q1 of the reflection mirror 41 and reflected. The optical axis a4 of the reflected light is incident on the point Q3 of the display area 4 of the windshield 3 through the opening 81 and reflected. 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 driver's manual input operation. 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. Thereby, the projection position of the image light to 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 as viewed from the driver can be adjusted so as to move up and down in the Z direction, for example. 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 according to the second embodiment, the LED substrate 12, the LED collimator 15, the polarization conversion element 21 and the like are used to ensure the light use efficiency and reduce the size of the device, and further reduce the size in the Y direction. In the light source device 10 and the adjustment optical system 40 of the HUD device 1 according to the second embodiment, light distribution control that realizes a predetermined convergence angle is necessary to generate suitable image light. The HUD device 1 according to the second embodiment also requires predetermined light distribution control for the return external light prevention function. In order to realize light distribution control that satisfies both of them, the HUD device 1 of the second embodiment has a configuration as shown in FIG. In this configuration, the optical axis (normal inclination angle) of the optical element such as the refractive element 43 is set to a predetermined 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). 10 ° or more) (see angle φ2 etc. in FIG. 30 described later).

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

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

  As a result, in the case where a plurality of components such as the LED elements 14 are arranged in parallel in the X direction, a plurality of components can be arranged compactly in the X direction, the size in the X direction of the device can be reduced, and the size can be reduced. Can contribute. Alternatively, more parts can be arranged within a predetermined size in the X direction of the apparatus. For example, a larger amount of light can be secured by arranging a large number of LED elements 14. In addition, since the degree of freedom of arrangement of components in the X direction is increased, it is easy to deal with various mountings of the HUD device 1. For example, mounting according to the sizes of various display areas 4 is facilitated.

  The light guide 17 has a substantially trapezoidal shape in the illustrated YZ cross section. The light guide 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 top portion 175 (including the top surface s5). Have. In this example, the incident surface s1 of the incident portion 171 is disposed with 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 portion 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 top surface s5. By providing the top portion 175, the emission 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. Furthermore, the emission surface s3 has a free-form surface shape. This free-form surface shape is a shape for realizing predetermined light distribution control. In addition, although the free-form surface shape of the output surface s3 is shown as a convex shape, it is not limited to this, and details will be described later.

  The refracting element 43 is configured by an optical element such as a lens having a predetermined refractive index, and has a concave shape on the incident side and the emission side as shown in FIG. 30, for example. The inclination of the concave surface of the refractive element 43 is gentler than the inclination of the concave surface of the refractive 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. However, the refractive element 43 may have a concave surface on the incident side and a convex surface on the output side as shown in FIG.

  The optical path of the image light is as follows. Schematically, the optical axis a1 in the Y direction from the LED element 14 becomes the optical axis a2 in the Z direction through reflection at the light guide 17. The optical axis a2 of the outgoing light from the light guide 17 is converted into directions (optical axes a22, a23) having a predetermined angle φ3 with respect to the Z direction through the action of the outgoing surface s3. With respect to the optical axis, the axes of the liquid crystal display element 50 and the refraction element 43 form a predetermined angle φ2. 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 refractive element 43 and have an angle φ2.

  The light emitting point of the LED element 14 is indicated by a point p1. The optical axis a1 in the Y direction from the point p1 is shown. A point p2 through which the optical axis a1 passes on the incident surface s1 of the light guide 17 is shown. A point p3 where the optical axis a1 hits the reflecting surface s2 of the light guide 17 is shown. By being reflected at the point p3, the optical axis a1 is converted to the optical axis a21 in the Z direction. A point p4 through which the optical axis a21 passes on the exit surface s3 is shown. The refracted optical axis a22 is shown through a point p4 on the exit surface s3. The optical axis a22 is incident on the point p5 of the liquid crystal display element 50 via the diffusion 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 image light on the optical axis a23 is incident on the point p6 of the refraction element 43, and receives 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 refractive element 43. The image light on the optical axis a24 enters the point Q2 of the reflection mirror 42 and is reflected to become the optical axis a3 described above.

  When the above-described external light is incident on the HUD device 1, the optical axis b3 of the external light from the reflection mirror 41 is reflected at the point Q2 of the reflection mirror 42, and the optical axis b4 (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 refractive element 43. In the second embodiment, the configuration having the angle φ2 on the optical axis has a characteristic that return external light is hardly generated. Of the external light on the optical axis b4, external light reflected by the refractive element 43 travels in a direction different from that of the comparative example. A ray b9 of reflected outside light corresponding to the outermost part of the range corresponding to the display area 4 in the outside light on the optical axis b4 is indicated. The light beam b9 is shifted from the optical axis b4 by an angle corresponding to twice the angle φ2. The reflected external light ray b <b> 9 hits the housing 80 or the like and is attenuated to make it difficult to return to the outside from the opening 81. Similarly, of the external light on the optical axis b4, the light of reflected external light when passing through the refractive element 43 and entering the liquid crystal display element 50 is indicated by a light ray b10. Similarly, the light beam b10 travels along an optical axis different from that of the image light, and hardly returns 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. Thereby, when the driver views the virtual image 7 through the point Q3 of the display area 4 with the line of sight 6, the virtual image 7 can be suitably viewed.

  As described above, according to the second embodiment, it is possible to reduce or reduce the quality of the virtual image 7 due to external light while ensuring the suitable image light of the HUD and preventing or reducing return external light as well as downsizing the apparatus. The configuration is not limited to the configuration of the optical axis and the like in FIG. 30, and any configuration having a free-form surface shape on the incident surface s1 or the exit surface s3 and a configuration having a predetermined angle φ2 on the optical axis may be used. As a configuration of another embodiment, the optical axis a22 of the light emitted from the light guide 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-form surface on the entrance surface s1 or the exit surface s3 of the light guide 17, it is possible to design the light distribution characteristics to be different for each position or region in the plane corresponding to the panel surface of the liquid crystal display element 50. is there. Thereby, the characteristic which suppresses return light efficiently can be implement | achieved.

[2-6: Light source module]
FIG. 31 is a perspective view illustrating an appearance of a mounting configuration example as a light source module of the light source device 10 according to the second embodiment. In this mounting configuration example, the LED substrate 12 provided with the LED elements 14 and the like is mounted as an 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 in a state in which a plurality of heat radiating fins come out of the light source device case 11. The aforementioned 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 17 and the like are accommodated 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. Thereby, the video display device 30 is configured as a module. Note that the panel surface of the liquid crystal display element 50 and the display area 4 of the HUD device 1 form a horizontally long screen that is relatively long in the X direction and short in the Z direction. Therefore, the light source device 10 has a mounting corresponding to the 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 being positioned and fixed to each other by means such as a screw, a positioning pin, and an uneven shape at a position such as the outer periphery. Yes. The LED board 12 and the LED collimator 15 are positioned and fixed with high accuracy by, for example, fitting between positioning pins and positioning holes and sandwiching and fixing the front and rear parts. Each part of the light source device 10 and the video display device 30 is fixed to the housing 80 of the HUD device 1.

[2-7: Light source module-inside casing]
FIG. 32 shows a configuration inside the light source device case 11 of the light source device 10. The LED board 12 is not shown, and has a plurality (six in this example) of LED elements 14 (14a, 14b, 14c, 14d, 14e, 14f) in the X direction, and are arranged at a predetermined pitch. An LED collimator 15 having a plurality of (six) collimator elements 15 </ b> A is disposed downstream of the plurality of LED elements 14 in the Y direction. The individual collimator portions having the above-described concave portion 153 and outer peripheral surface 156 are 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 respect to the common substrate portion, for example, with a translucent resin. A polarization conversion element 21 is disposed downstream of 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, components such as the PBS film 211 and the translucent member 214 described above extend in the X direction, and a plurality of components are arranged symmetrically in the Z direction. The polarization conversion element 21 may be accommodated in a polarization conversion element holder (not shown). An orientation control plate 16b is disposed after the phase plate of the polarization conversion element 21. An incident portion 171 of the light guide 17 is disposed downstream of the orientation control plate 16b. The side part 174 in the X direction of the light guide 171 and the top part 175 are provided with attachment parts to the housing 80. The exit surface s3 of the exit portion 173, which is the upper surface of the light guide body 171, has a free-form surface as shown in the figure. A diffusion plate 18b is disposed above the emitting portion 173 in the Z direction. A configuration in which the light distribution control plate 16b and the diffusion plate 18b are not provided is also possible. In this embodiment, the composite 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 an enlarged view schematically showing the structure and light rays of the LED substrate 12, LED element 14, LED collimator 15, and polarization conversion element 21 of the light source unit 301, as viewed from the side of the apparatus (X direction). It is YZ sectional drawing. The concave portion 153 of the LED collimator 15 is disposed 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 (substrate surface on which the LED element 14 is mounted). ing. The top surface of the recess 153 is disposed so as to contact the light emitting surface of the LED element 14. As described above, the collimator element 15A includes the concave portion 153 that is the lens portion on the incident side, the outer peripheral surface 156 that is the reflector portion, and the emission surface 154 that is the lens portion on the emission side. The concave portion 153 has an incident surface 157 on the bottom surface side in the Y direction, and has a convex curved surface on the incident side. On the exit surface 154, a convex portion 155 that is convex on the exit side is formed at a portion of the recess 153 that faces the entrance surface 157. The incident surface 157 and the convex portion 155 constitute a convex lens function having a condensing function.

  Light emitted from the point p1 of the LED element 14 passes through the air in the concave portion 153 of the collimator element 15A, proceeds as shown in the example of the illustrated light beam, and is emitted out of the concave portion 153. The light rays emitted from the recess 153 are collected while some of the light rays are reflected by the substantially conical outer peripheral surface 156 (reflector portion). The light traveling in the peripheral direction of the optical axis a1 is totally reflected by the paraboloid of the outer peripheral surface 156. These rays are emitted as parallel light in the Y direction through the emission surface 154. The exit surface 154 is disposed so that the incident surface of the polarization conversion element 21 is in contact therewith.

  Parallel light from a plurality of (six) LED elements 14 and collimator elements 15A is incident on the polarization conversion element 21 in the X direction. The cross section of the optical axis a1 of these individual LED elements 14 is the same as shown in FIG. As described above, the polarization conversion element 21 includes a parallelogram-shaped light-transmitting member 214, a triangular light-transmitting member 215, a PBS film 211, a reflective film 212, a 1 / 2λ phase plate 213, and the like. Yes. The translucent member 214 is a parallelogram in the YZ section, and the translucent member 215 is a triangle in the YZ section. Each component is arranged 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 disposed on the optical axis a1 and the translucent member 214 disposed 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 disposed further outside. 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 (P-polarized wave) that has passed through the PBS film 211 through the translucent member 214 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 reflection film 212. The reflected light is emitted from the emission surface of the translucent member 214 through the 1 / 2λ phase plate 213 as light whose phase is adjusted (P-polarized wave). That is, in the polarization conversion element 21, all the light from the plurality of LED elements 14 is emitted as P-polarized waves. Thereby, since the optical path length difference is small, 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 (a state in which the horizontal and vertical directions are transposed). Is arranged. Thereby, 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 elements 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 accordance with the specifications of the HUD device 1 and the manufacturing yield is improved.

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

  In the light source device 10 according to the second embodiment, the video display device 30 using the liquid crystal display element 50, and the HUD device 1, in order to realize a predetermined high output and high efficiency LED light source, LEDs arranged per unit area By increasing the number of elements 14 and the like as much as possible, a large amount of light and brightness, high light utilization efficiency, and uniformity of in-plane light intensity are realized. Alternatively, even when the number of LED elements 14 is the same as the conventional one, 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 pair 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 indicated 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. A circle around the point q corresponds to the end of the outer peripheral surface 156. A substantially conical outer peripheral surface 156 is indicated 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 components that constitute the polarization conversion element 21, extend in the X direction. Each of these components is arranged in parallel to a plane (XZ plane) orthogonal to the optical axis a1. These components are arranged at positions and shapes that are vertically symmetrical in the Z direction with respect to a virtual plane that 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. The translucent member 215 disposed 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. Furthermore, the two translucent members 215b arranged on the outer sides thereof have a triangular prism shape whose cross section is a right triangle. The PBS film 211 and the reflection 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 to each other on the bonding surface 216. In addition, the bonding surface 216 preferably has an optically transparent configuration after bonding. In this configuration, the upper component 21u and the lower component 21d can be composed of the same component. 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, it is possible to achieve commonality of components and simplification of the configuration, thereby further reducing the cost.

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

  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 position of each point p is the same in the upper and lower polarization conversion element sections. In the XZ plane, the point q corresponding to the light emission axis of the plurality of LED elements 14 is arranged in a rectangular shape. Moreover, the diameter of the circular area | region corresponding to the outer peripheral surface 156 of 15 A of collimator elements is shown by the distance D2. In this example, a plurality of collimator elements 15A in the X direction are arranged as close as possible while securing the individual distances D2. It arrange | positions so that the surface of the LED element 14 may be settled in the top surface of each recessed part 153. FIG.

  FIG. 35B shows another example of the configuration in which 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 portion 21-2 are shifted by a half distance of the pitch (distance D2) with respect to the upper polarization conversion element portion 21-1. In the XZ plane, the points q corresponding to the light emission axes of the plurality of LED elements 14 and the like are arranged in a triangle. Similarly, a configuration in which a plurality of sets of polarization conversion element units are arranged in the Z direction is not limited to two rows, if necessary.

  As described above, in the second embodiment, with respect to the arrangement configuration of the polarization conversion element 21, in the X direction, there are few restrictions when arranging the plurality of LED elements 14 and the like, and the degree of freedom of arrangement is high. In the first embodiment described above, for example, as shown in FIG. 4, the polarization conversion element 21 has a plurality of components extending in the Z direction and arranged in the X direction. Therefore, the polarization conversion element 21 is configured as a plurality (two) of polarization conversion element units in the X direction, and the position of the optical axis 15c in the X direction and It has a constraint width 21w. Corresponding to the configuration of the polarization conversion element 21, the LED element 14 and the collimator unit need to be arranged at predetermined positions. For this reason, for example, even if a large number of LED elements 14 and the like are 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, the restrictions on the arrangement of components such as the LED elements 14 in the X direction are smaller than in the first embodiment, and the degree of freedom in arrangement is high. The polarization conversion element 21 is not divided into a plurality of parts (groups) in the X direction, and the components extend continuously. Therefore, in the X direction, the LED element 14 and the like can be arranged at a somewhat free position. For example, as shown in FIG. 35 (a), it is also possible to arrange a plurality (N) of LED elements 14 and the like in the X direction with a pitch as short as possible (distance D1). By arranging a large number of LED elements 14 and the like within a predetermined size in the X direction, the light quantity of the light source can be increased and the apparatus can be reduced in size.

[2-11: Multiple LED elements (N = 5)]
FIG. 36 is an explanatory diagram regarding an arrangement configuration of the plurality of LED elements 14, the plurality of collimator elements 15 </ b> A, and the polarization conversion element 21 in the second embodiment. In the present embodiment, a case is shown in which N = 5 as the number of LED elements 14 or the like arranged in the X direction. 35A shows the configuration of the XY plane, FIG. 35B shows the configuration of the XZ plane of the corresponding polarization conversion element 21, and FIG. 35C shows the configuration of the corresponding polarization conversion element 21. The structure of a YZ plane is shown. In this example, collimator elements 15a to 15e are provided as the collimator elements 15A corresponding to 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 indicated by a distance DA. The height in the Z direction of the polarization conversion element 21 is indicated by a distance DB. Of the distance DB, the width of the vertically symmetrical portion with respect to the optical axis a1, which is a half of the distance DB, is indicated by a distance DC. The thickness in the Y direction of the polarization conversion element 21 (excluding the 1 / 2λ phase plate 213) is indicated by a distance DD.

  In the present 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 inclined surfaces of the PBS film 211 and the reflective film 212 is (45 ° ± 20 ′), where the unit is 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 and the like, and the width in the Z direction is the translucent member. It is the same as the width of the exit surface 214. The distance DA of the polarization conversion element 21 is, for example, 44 ± 0.2 mm in the first type embodiment that is relatively small, and 74 ± 0.2 mm in the second type embodiment that is relatively large.

[2-12: Comparative example]
FIG. 37 similarly shows the configuration of the comparative example for the N = 5 configurations of FIG. In this comparative example, N = 5 LED elements 14 and collimator elements 15A are similarly arranged in the X direction. In this comparative example, the polarization conversion element 21 is configured using five sets of polarization conversion element units in the X direction. The width DB of the width of one set of polarization conversion element portions is the same as the width of FIG. In this comparative example, the pitch (distance D1b) of the arrangement of the LED elements 14 and the collimator elements 15A is larger than the pitch (distance D1) of FIG. Is larger than the size (distance DA) in FIG.

  As described above, according to the second embodiment, the size of the apparatus can be reduced as compared with the comparative example. Or according to Embodiment 2, when it is set as the same predetermined size (distance DAb) as a comparative example, more LED elements 14 grade | etc., Can be arrange | positioned within the range, and a light quantity can be enlarged. In the light source device 10 according to the second embodiment, the number (N) of 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 further reduced in the light source unit 301 or the like in which a predetermined number of LED elements 14 are provided.

  According to the second embodiment, a plurality of LED elements 14 and the like can be relatively freely arranged in the X direction with respect to the polarization conversion element 21 within predetermined conditions. Therefore, according to the specifications of the HUD device 1 (for example, the size of the display area 4), the light source device 10 can be easily mounted by changing the number and position 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: Mounting example of a plurality of LED elements (N = 5)]
FIG. 38 shows a case of N = 5 corresponding to FIG. 36 as an implementation example including an array of a plurality of LED elements 14 and the like in light source device 10 of the second embodiment. 38A shows a top view in the XY plane, and FIG. 38B shows a side view in the corresponding YZ plane. In the X direction, the approximate widths of the LED substrate 12, the LED collimator 15, the polarization conversion element 21, the polarization control plate 16b, the light guide 17, and the like are indicated by a 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 having a predetermined pitch. For example, when the light source device 10 is mounted with a priority on small size, low cost, low power consumption, etc., as in the mounting example of FIG. 38, N = 5 LED elements 14 and the like are provided within a predetermined distance DA1. Be placed.

[2-14: Mounting example of a plurality of LED elements (N = 6)]
FIG. 39 shows a case where N = 6 as a mounting example including an array of a plurality of LED elements 14 and the like as the light source device 10 of the modified example, similarly to FIG. In the X direction, the approximate size of the LED substrate 12 and the like is indicated by a 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 increased to increase the light source light quantity as much as possible, 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 Embodiment 2, the degree of freedom of arrangement of 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, so both the examples in FIGS. 38 and 39 are used. It can be easily realized. That is, the mounting which changes the number (N) of the LED elements 14 according to the specification of the HUD device 1 can be realized relatively easily. For example, it is easy to reduce the number (N) of LEDs from the configuration of FIG. 39 and change to the configuration of FIG.

[2-15: Light guide]
FIG. 40 is a perspective view showing a free-form surface shape and the like of the emission surface s3 of the emission part 173 of the light guide body 17. 40A is a perspective view, and FIG. 40B shows a configuration of the YZ plane when the side surface portion 174 is viewed. In (a), on the emission surface s3 of the emission part 173, a free curved surface part 173a is provided inside the outer peripheral plane part 173b. 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 top surface s5 of the top portion 175 also has an attachment portion to the housing. The emission surface s3 is a slope having an angle φ1 with respect to the horizontal plane. The slope has a free curved surface portion 173a.

  The emission surface s3 of the emission part 173 of the light guide 17 has a shape corresponding to the panel surface of the liquid crystal display element 50 to be arranged later. The exit surface s3 and the entrance surface s1 have different shapes and areas. The area of the exit surface s3 is larger than the area of the entrance 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 another direction (for example, the X direction) orthogonal to the one direction. In the emission unit 173, the light distribution angle in one direction (for example, the Y direction) may be wider than the light distribution angle in another direction (for example, the X direction) orthogonal to the one direction. In the entrance surface s1 and the exit surface s3, the curvature may be different within the surface. For example, the curvature may be larger at the peripheral part than at the central part in the plane.

  FIG. 41 shows the structure of the reflecting portion 172 and the like of the light guide body 17. 41A shows the configuration of the YZ plane, and FIG. 41B shows a partial enlargement of the reflecting surface s2. In (a), the distance between the emission surface s3 and the reflection surface s2 is shown as an inter-surface distance Dt. The inter-plane distance Dt has a maximum distance Dtmax near the incident surface s1, and has a minimum distance Dtmin near the top surface s5 (Dtmax> Dtmin). The height of the top 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 reflecting surface s2 is basically arranged as a slope having a predetermined angle with respect to the horizontal plane. Specifically, the reflection surface s2 has a sawtooth shape (step shape) in which the reflection surface 172a and the connection surface 172b are alternately repeated, as in the first embodiment. (B) shows the part of the reflective surface 172a and the connection surface 172b of n = 1-9 near the incident surface s1. (C) shows the part of the reflective surface 172a and the connection surface 172b of n = 64-75 near the parietal surface s5. As described above, the pitch in the Y direction of the plurality of reflecting surfaces 172a is indicated by P1, etc., 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. .

  In this way, predetermined alignment control is realized by the structure of the light guide body 17 including the incident portion 171, the reflection portion 172, the emission portion 173, and the crown portion 175, and light having an inclination angle φ2 with respect to the Z direction in the emitted light. An axis a22 is configured (corresponding to the configuration in FIG. 30).

  Further, such a shape of the light guide 17 has an advantage that it can be easily manufactured at the time of manufacture. When producing the light guide 17 in large quantities at low cost, it is effective to produce it using a manufacturing method such as injection molding. When the manufacturing method is used, when the light guide 17 has a substantially triangular cross section as shown in FIG. 8 as a comparative example, it is possible to ensure the accuracy of injection molding at the side corresponding to the acute vertex of the triangle. There is a problem that it is relatively difficult and expensive. Specifically, since there is a non-uniformity in accordance with the difference in the portion of the light guide 17 (incident surface and the opposite side) with respect to the cooling rate of the molten resin in the mold at the time of injection molding, high-precision molding Is relatively difficult. Since the shape of the light guide 17 is designed to have a predetermined orientation control characteristic, when the shape of the light guide 17 after injection molding is largely deviated from the design shape, the light distribution control The quality of the characteristics is reduced.

  On the other hand, in the second embodiment, as shown in FIG. 41, the light guide 17 has a substantially trapezoidal cross section and has a top 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 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 not uniform according to the difference between the parts (incident surface 171 and the top of the head 175). Is suppressed. Therefore, the light guide body 17 has an advantage that it can be molded with higher accuracy, can improve the quality of the characteristics of light distribution control, and can be mass-produced at low cost. A processing example of the mold at the time of manufacturing the light guide body 17 of the second embodiment, in particular, the reflection portion 172 is the same as that in FIG.

[2-16: Orientation control]
FIG. 42 shows the configuration of the orientation control of the light source device 10 and the video display device 30 according to the second embodiment. The illumination light of the light source device 10 and the optical axis and each light beam of the video light of the video display device 30 are viewed from the X direction. Shown in the YZ section. In addition, the reflecting surface 172a and the connecting surface 172b of the light guide 17 are schematically illustrated in an enlarged manner. In the present embodiment, the incident surface s1 of the light guide body 17 is a flat surface arranged at an angle 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 on the incident surface s1 of the light guide 17 and is refracted to become an optical axis a12. The optical axis a12 is reflected at the point p3 on the reflecting surface s2, and becomes the optical axis a21 in the Z direction. The exit surface s3 has a free-form surface disposed obliquely with an angle φ1 with respect to the Y direction, and has a predetermined refraction characteristic. An optical axis a21 in the Z direction from the reflecting surface s3 is refracted through a point p4 on the free curved surface of the exit surface s3, and becomes an 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. Similarly, the image light generated by the liquid crystal display element 50 becomes an optical axis a23 having an angle φ3. The light beam L30 of the image light on the optical axis a23 is incident on the refractive element 43 described above.

  Further, in this embodiment, the diffusion plate 18 a is disposed near the back surface of the liquid crystal display element 50 above the light emitting unit 173 in the Z direction. The diffusion plate 18a and the liquid crystal display element 50 are roughly arranged on a horizontal plane. Specifically, the diffusion plate 18a and the liquid crystal display element 50 are disposed on a plane having an angle φ5 with respect to the horizontal plane.

  In the illumination optical system 302, complicated light distribution control is required for the above-mentioned suitable illumination light and for realizing prevention of return light. This light distribution control is realized by the orientation control of FIG. The light distribution control along the YZ plane in FIG. 42 is represented by 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 17, the reflection angle of the reflection surface s2, the refraction angle of the free-form surface of the emission surface s3, and the like. Further, the light distribution control in the X direction is realized by a refraction angle or the like by the free-form surface shape of the emission surface s3. The light distribution control plate 16b controls light diffusion in the Z direction. The diffusion plate 18b controls light diffusion in the X direction and the Y direction. Due to the orientation control characteristics of the light source device 10 according to the second embodiment, the degree of freedom corresponding to the orientation angle of the illumination light can be improved as compared with the prior art, and suitable image light characteristics required for the HUD device 1. Can be improved. In accordance with the characteristics of the adjustment optical system 40 and the liquid crystal display element 50 of the HUD device 1, it is easy to mount the light source device 10 having predetermined alignment control characteristics. For example, the characteristics of the illumination light can be adjusted by designing the free curved surface shape of the emitting portion 173 of the light guide body 17. Further, it is possible to adjust the characteristics of light distribution control for preventing suitable image light and returning external light.

[2-17: Light distribution control board]
FIG. 43 shows a cross-sectional configuration of the light distribution control plate 16b in the light source device 10 of the second embodiment. (A) of FIG. 43 shows the XY cross section of the light distribution control board 16b. In the Y direction, the light distribution control plate 16b is a flat surface on the incident side and a sawtooth surface on the light emission side. FIG. 43B shows a partial enlargement of the exit surface of the light distribution control plate 16b. A plurality of triangular cross sections are repeatedly formed as a texture on the emission surface in the Z direction. In the plurality of triangular slopes, a first slope having a positive angle γ with respect to the X direction and a second slope having a negative angle γ with respect to the X direction are alternately repeated. The pitch of the triangle arrangement in the X direction is indicated by a 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 function of the texture of the exit surface. For example, the light distribution control plate 16b may be a diffusion plate having an elliptical distribution of diffusion angles.

  The orientation control plate 16b has light diffusibility in the X direction. The diffusing plate 18b has light diffusibility in the Y direction. By the action of the orientation control plate 16b and the diffusion plate 18b, the in-plane intensity distribution of the light emitted from the light guide 17 is made uniform, and a suitable planar illumination light can be obtained. In the second embodiment, compared to the first embodiment, since the plurality of LED elements 14 and the like can be arranged at positions closer to each other in the X direction, the uniformity in the X direction is further improved in combination with the diffusibility of the orientation control plate 16b. To do. Note that the uniformity in the Z direction can be realized by controlling the ratio between the reflecting surface 172a and the connecting portion 172b formed on the reflecting portion 172 of the light guide 17, as described with reference to FIG. It is. As a result, the minimum diffusibility can be realized, the light use efficiency can be 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 incident surface s1 and the exit surface s3 of the light source device 10, the orientation control plate 16b, the diffusion plate 18b, and the light guide 17. Good. In that case, the characteristics of the functional scattering surface are the same as those in FIG.

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

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

  First, in FIG. 40A described above, a free curved surface portion 173a is provided on the inner side of the flat surface portion 173b of the outer frame in the emission surface s3 of the emission portion 173. An example of how to set 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 center point K2 (corresponding to the point p4) of the free-form surface. The x axis corresponds to the X direction, and the y axis corresponds to the Y direction. The reference position of the emission part 173 of the light guide 17 is indicated by a broken line. In this example, the reference position is the position at the beginning of the slope close to the incident surface s1 side. In FIG. 40B, the distance from the reference position of the emitting portion 173 of the light guide 17 to the x-axis (point K2) of the free-form reference coordinate system is indicated by a distance Dy0. In this example, Dy0 = 18 mm. The center of the y-axis is the center of the light guide 17. In addition, the angle formed between the horizontal plane and the y-axis is an 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 indicates the inside of the exit surface s3 as positive.

  The range of the free-form surface was set to −21 mm ≦ x ≦ 21 mm and −15 mm ≦ y ≦ 16 mm. In general, the width in the X direction is 42 mm and the width in the Y direction is 31 mm. 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), the outer surface is cut as a flat surface on the emission surface s3, and a concave portion of a free-form surface exists as indicated by a dotted line from the flat surface to the inner side. In addition, as another Example, it is good also as a structure where the convex part of a free-form surface exists in the outer side (outgoing direction) from the outgoing surface.

  FIG. 44 shows formulas and coefficients for defining the free-form surface shape of the emitting portion 173 of the light guide 17 in the second embodiment. (A) of FIG. 44 shows Formula 1 which is a free-form surface formula of general expression. As shown in Equation 1, the free-form surface is represented by z (x, y) = Σ {ai · bi (x, y)}. Σ is an addition from the subscript i = 0 to 14. ai · bi represents a coefficient and a variable. z (x, y) represents a z value corresponding to the value of the position coordinate of (x, y). The unit is mm.

  FIG. 44B shows the coefficients and variables of Equation 1 in tabular form. For example, when i = 0, b0 = 1 and a0≈1.0269. When i = 1, b1 = x and a1≈−0.0015. When i = 2, b2 = y and a2≈−0.0032. When i = 3, b3 = x ^ 2 and a3≈−0.0052. When i = 14, b14 = y ^ 4 and a14 = 5.3049E-06. E is an index. For example, E-06 indicates 1/10 to the sixth 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: Effects, 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 small and light, has high light utilization efficiency, and is modularized and easily used as a planar light source. It is possible to provide a light source device that can be used. More specifically, the light utilization efficiency from the LED light source and the uniform illumination characteristics can be further improved. In addition, a light source device suitable as an illumination light source that can be manufactured at low cost can be provided. Further, it is possible to provide the video display device 30 that generates suitable video light and the light source device 10 that generates suitable illumination light in accordance with the characteristics of the HUD device 1 and the liquid crystal display element 50. In addition, it is possible to provide the HUD device 1 that can prevent return external light and has a good virtual image display characteristic. Mounting by which the area of the image light is enlarged with respect to the illumination light by the light distribution control in the light source device 10 is easy.

  (1) In the light source device 10 according to the second embodiment, the light guide 17 has a free curved surface shape for realizing predetermined light distribution control on at least one of the incident surface s1 and the exit surface s3. Thereby, the characteristic of the light distribution control which implement | achieves suitable illumination light and a return external light prevention function is implement | achieved.

  (2) In the light source device 10, the video display device 30, and the HUD device 1, the axis (normal inclination) of the liquid crystal display element 50 and the refraction element 43 is predetermined with respect to the optical axis of the light emitted from the light guide 17. It is slanted at an angle. The light guide 14 has a trapezoidal cross section, and the emission surface s3 is disposed as an inclined surface with respect to the horizontal. Thereby, the characteristic of the light distribution control which implement | achieves a suitable image light and a return external light prevention function is implement | achieved.

  (3) In the light source device 10, the light guide 17 has the structure of the reflection part 172 similar to that of the first embodiment, and thereby high light use efficiency is achieved and suitable illumination light is realized.

  (4) The light source device 10 has a configuration in which the LED element 14, the LED collimator 15, the polarization conversion element 21, and the like are combined in addition to the configuration of the light guide body 17. Realize the characteristics. For example, the polarization conversion element 21 has components extending in the X direction, and a plurality of LED elements 14 and the like are arranged in the X direction corresponding to the components. Thereby, the predetermined light distribution control in the light source device 10 can reduce the burden of light distribution control required by the liquid crystal display element 50 and the adjustment optical system 40 (refractive element 43, etc.), and can easily take measures against external light flare. Become.

[2-22: First modification]
FIG. 45 shows the configuration of the light source device 10 of the first modification of the second embodiment on the YZ plane. In the first modification, the incident surface s1 of the incident portion 171 of the light guide 17 is a free-form surface, and the exit surface s3 of the exit portion 173 is a planar shape. A predetermined light distribution control characteristic is realized by the structure including the free-form surface 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-form surface shape. In the configuration example of FIG. 45, the optical axis from the reflecting portion 172 and the optical axis from the emission surface s3 are inclined at an angle φ3 to the left in the Y direction with respect to the Z direction, and the axis of the liquid crystal display element 50 It is inclined at an angle φ2.

[2-23: Second modification]
FIG. 46 shows the configurations of the light source device 10 and the video display device 30 of the second modification of the second embodiment on the YZ plane. In the second modified example, as a different configuration point from the above-described embodiment, not only the emitting portion 173 of the light guide 17 but also the incident surface s1 of the incident portion 171 has a free-form 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-form surface that is convex on the incident side with respect to the reference plane of the incident surface s1. The characteristics of the free curved surface of the incident surface s1 and the characteristics of the free curved surface of the exit surface s3 are combined so that the light guide 17 has predetermined light distribution control characteristics. Thus, by making both the incident part 171 and the emission part 173 into free-form surfaces, 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 more accurately realize characteristics such as suitable image light and return external light prevention.

[2-24: Third modification]
FIG. 47 is a perspective view of an example of a relatively large light source device 10 that realizes a large area light source 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, the third modification includes a light guide 19 that guides light in the Z direction. The light guide 19 is a light distribution control member that realizes predetermined light distribution control characteristics.

  47A shows the component arrangement in the case, and the illustration of the LED substrate 12 and the like is omitted. A plurality of LED elements 14, an LED collimator 15, a polarization conversion element 21, an alignment control plate 16b, a light guide 19, and a liquid crystal display element 50 are arranged in order from bottom to top in the Z direction. Each of these components is roughly a flat plate shape on the XY plane, and the side in the X direction is longer than the side in the Y direction. The sides in the X direction correspond to the horizontally long sides of the liquid crystal display element 50 and the display area 4 of the HUD device 1.

  The polarization conversion element 21 is configured using two sets of polarization conversion element units 21a and 21b arranged in the Y direction. In the Y direction, the first polarization conversion element unit 21a is provided on the left side of the figure and the second polarization conversion element unit 21b is provided on the right side, and they are arranged adjacent to each other. Each set of polarization conversion element portions has the same structure, and the components extend in the X direction.

  A plurality of LED elements 14 and a collimator element 15 </ b> A 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 in the X direction with respect to one polarization conversion element portion 21a. Nine collimator elements 15 </ b> A are arranged in the X direction corresponding to the LED elements 14. Similarly, N = 9 LED elements 14 (14-10, 14-11,..., 14-18) and corresponding collimator elements 15A in the X direction have a predetermined pitch with respect to the other polarization conversion element portion 21b. Is arranged in. That is, in the present embodiment, nine LED elements 14 and a collimator element 15A are arranged in a total of 18 lines in the X direction, 1 line in the Y direction, 2 lines in the Y direction, and XY plane. Thereby, a planar light source having a relatively large area is configured.

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

  47B is a partial cross-sectional view of FIG. 47A, and shows a YZ cross section at the position of the LED element 14-5 near the center in the X direction. The light guide 19 has an incident part 191 (including an incident surface) on the lower side in the Z direction, and an output part 192 (including an outgoing surface) on the upper side in the Z direction. Each of the entrance surface and the exit surface has a free-form surface shape. The free-form surfaces of the entrance surface and the exit surface have convex curves on the Z direction (exit side) when viewed in the YZ section. The free curved surfaces of the entrance surface and the exit surface have concave curves in the Z direction when viewed in the XZ section. Optical axes a31 and a32 passing through the polarization conversion element 21 and the light guide 19 are shown. The optical axes a31 and a32 cause predetermined refraction, light diffusion, and the like by a free-form surface. Predetermined light distribution control characteristics are designed by such a free-form surface shape of the light guide 19. Thereby, according to the light source device 10 of the third modified example, characteristics such as suitable image light and prevention of returning external light are realized.

  The free curved surface shape of the light guide 19 in FIG. 47 will be described with reference to FIGS. 48 and 49. FIG. 48 is a perspective view of the light guide 19 and shows an example of how to take a free-form reference coordinate system (x, y, z). The reference coordinates of the emission surface of the emission part 192 are coordinates inclined at an angle θy (for example, θy = 1 °) with respect to the horizontal plane direction 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) with respect to the center position of the light guide 19. There is no offset of the reference coordinate of the incident surface on both the angles θy and the y-axis.

  FIG. 49 shows free-form surface equations and coefficients. 49A shows a free-form surface expression similar to that described above, FIG. 49B shows an example of coefficients and variables of the exit surface of the exit portion 192, and FIG. 49C shows the entrance surface of the entrance portion 191. An example of a coefficient and a variable is shown. The range of the free curved surface of the light guide 19 was set to −40 mm ≦ x ≦ 40 mm and −22 mm ≦ y ≦ 2 mm. In general, the width in the X direction is 80 mm and the width in the Y direction is 24 mm. Further, when the value of z (x, y) is smaller than −8 mm on the incident surface, the value is forcibly set to −8 mm. In other words, a portion that protrudes greatly downward in the Z direction (near both ends in the Y direction in the drawing) was cut at a position of −8 mm to obtain a flat surface.

[2-25: Fourth modification]
FIG. 50 shows an example where a small light source with a relatively small area is realized as the light source device 10 and the image display device 30 of the fourth modification of the second embodiment. FIG. 50A is a perspective view of the light source device 10 with the liquid crystal display element 50 attached thereto, and FIG. 50B is a partial cross-sectional view of the light source apparatus 10 with the liquid crystal display element 50 removed. A perspective view including the light distribution and the like are shown. In the 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 19b is disposed after the light distribution control plate 16b. In other words, the light guide 19b is a light distribution control plate, and has a predetermined light distribution control characteristic of guiding light roughly in the Y direction. The light guide 19b has an incident part 19b1 and an emission part 19b2. Because of its characteristics, the light guide 19b has a free-form surface on both the entrance surface and the exit surface. In the YZ section of the light guide 19b, the entrance surface and the exit surface are free-form surfaces including a convex curve on the entrance side in the Y direction.

  On the exit side of the light guide 19b in the Y direction, a reflection mirror 500 is further arranged with an inclination angle oblique to the horizontal plane. The optical axis in the Y direction is roughly converted into an optical axis in the Z direction through reflection by the reflection mirror 500. Above the reflection mirror 500 in the Z direction, the diffusion plate 18b and the liquid crystal display element 50 are arranged on the XY plane.

  The plurality of LED elements 14 are arranged such that N = 5 LED elements 14 (14a to 14e) in the X direction are packed at a predetermined pitch as much as possible. Similarly, the LED collimator 15 has a plurality of collimator elements 15A arranged in the X direction. Thereby, the planar light source part 301 of a comparatively small area is comprised. The light in the Y direction from the LED element 14 passes through the light distribution control plate 16b and then enters the incident surface of the incident portion 19b1 of the light guide 19b. The light incident on the incident surface of the incident portion 19b1 is guided while being refracted along the free-form surface, and is emitted from the output surface of the emitting portion 19b2. Specifically, as in the example of the light beam shown in (b), the emitted light is condensed toward the reflection mirror 500, and the range of the light beam in the Z direction is narrowed. For example, a light beam that passes through a position above the central optical axis in the Z direction is converted into a light beam that is inclined downward, and a light beam that passes through a lower position in the Z direction is converted into a light beam that is inclined upward. .

  The light that has passed through the light guide 19 b is reflected upward in the Z direction by the reflection mirror 500. The reflected light is incident on the panel surface of the liquid crystal display element 50 as illumination light while being diffused through the diffusion plate 18b. The illumination light is condensed through the light guide 19b and the reflection mirror 500, and converted into illumination light having a relatively small area. In the plane of the diffusion plate 18b, the illumination area 501 by light collection is indicated by a dotted line. The illumination light passes through this illumination area 501. The illumination area 501 has a smaller area than the area of the panel surface of the liquid crystal display element 50. In this embodiment, the illumination light for the liquid crystal display element 50 may be a planar illumination light having a small area as indicated by the illumination area 501. For example, the display area 4 of the HUD device 1 has a relatively small area. Corresponds to the case. In the case of such an application, the configuration of the light source device 10 as in the fourth modified example is suitable.

[2-26: Fifth modification]
FIG. 51 is a perspective view showing configurations of the light source device 10 and the video display device 30 according to a fifth modification of the second embodiment. 51, the configuration on the right side in the Y direction with respect to the broken line 511 in the Z direction is the same as the configuration in FIG. 42 and the like described above, and includes a reflecting portion 173, an emitting portion 172, and a top portion 175. The configuration of the left part in the Y direction is different from that of the broken line 511. 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 board 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, and the arrangement directions are different.

  The light guide 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 on the incident side. The shape of the portion on the left side in the Y direction from the broken line 511 of the light guide body 17 has a roughly triangular prism shape, extends in the X direction, and the YZ cross section is a substantially triangular shape. The incident surface s6 of the incident portion 176 is roughly disposed on the horizontal plane (XY plane). The reflecting surface s7 of the reflecting portion 177 is an inclined surface having a predetermined angle with respect to the horizontal plane. The reflection surface s7 of the reflection unit 177 may be formed as a repetition of the reflection surface and the connection surface, similarly to the right reflection unit 173, and is not limited thereto, and may be formed of a reflection film or the like.

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

  In the configuration of the fifth modified example, the components such as the light source unit 301 are arranged in the Z direction using the incident portion 176 and the reflecting portion 177 of the light guide body 17. In comparison, the dimension 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 modified example, the incident surface s6 of the incident portion 176 is a flat surface, but is not limited thereto, and may be a free-form surface shape for realizing predetermined light distribution control characteristics.

[2-27: Sixth Modification]
As the light source device 10 of the sixth modified example of the second embodiment, the incident surface s1 of the light guide 17, the emission surface s3 of the emission unit 173, or the reflection surface s2 of the reflection unit 172, and the above-described FIG. Similarly, a texture constituting the functional scattering surface may be provided. For example, a texture as shown in FIG. 22 may be provided on the reflective surface s2 of the reflective portion 172 of the light guide body 17 of the second embodiment or each modified example. 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.

  FIG. 22A schematically shows a first example of the texture of the target surface (reflection surface s2). In FIG. 22B, a second example of the texture of the target surface is schematically shown. In the texture (a), boundaries between a plurality of reflecting surfaces and connecting surfaces are linearly arranged and formed. The extending direction of the straight line corresponds to the X direction in which the plurality of LED elements 14 are arranged. With such a texture, light distribution control such as light diffusion is performed in a direction in which a plurality of boundaries are arranged (the direction of a stepped slope, the Y direction on the corresponding emission surface s3). In the texture (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. Thereby, more precise light distribution control is possible.

  Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. It is possible to add, delete, separate, merge, replace, and combine components of the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Head-up display (HUD) apparatus, 3 ... Wind shield, 4 ... Display area, 5 ... Eye, 6 ... Line of sight, 7 ... Virtual image, 10 ... Light source device, 12 ... LED board, 13 ... Heat sink, 14 ... LED element 15 ... LED collimator, 16b ... orientation control plate, 17 ... light guide, 18b ... diffusion plate, 21 ... polarization conversion element, 30 ... video display device, 41, 42 ... reflection mirror, 43 ... refraction element, 50 ... liquid crystal Display element, 80... Casing, 81... Opening, 171... Incident part, 172.

Claims (13)

A light source unit including a plurality of semiconductor light source elements for generating light;
A collimator including a plurality of collimator elements disposed on the light-emitting axis of each of the plurality of semiconductor light source elements;
A light guide disposed on the exit side of the collimator;
With
The light guide includes an incident portion having an incident surface on which light on the light-emitting axis from the semiconductor light source element is incident, and an emitting portion having an output surface that emits the light, and the incident surface or the emission surface At least one of the surfaces has a free-form surface shape for realizing predetermined light distribution control,
Light source device. The light source device according to claim 1,
The plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction orthogonal to the light emission axis,
The light source unit, the collimator, and the light guide are arranged in a second direction corresponding to the light emission axis,
The light guide has a column shape extending in the first direction, and reflects light in the second direction incident from the incident surface in the third direction orthogonal to the first direction and the second direction. And including a reflecting portion having a reflecting surface for emitting from the emitting surface,
Light source device. The light source device according to claim 1,
The plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction orthogonal to the light emission axis,
The light source unit, the collimator, and the light guide are arranged in a second direction corresponding to the light emission axis,
The light guide body guides the light in the second direction incident from the incident surface in the second direction and emits the light from the emission surface.
Light source device. The light source device according to claim 2,
The light guide has a top portion having a top surface that is in contact with one side of the emission surface and one side of the reflection portion on the opposite side to the incident surface, and the emission surface is in the second direction. Having a predetermined angle with respect to
Light source device. The light source device according to claim 2,
The reflecting portion includes a plurality of reflecting surfaces and a plurality of connecting surfaces having an angle greater than a critical angle with respect to parallel diffused light from the incident surface, and the reflecting surfaces and the connecting surfaces are sawtooth alternately. Formed in a shape,
Light source device. The light source device according to claim 2,
The reflection part has a reflection film or a reflection mirror,
Light source device. The light source device according to claim 1,
A light distribution control plate or a diffusion plate for performing predetermined light distribution control is disposed on the incident side of the incident surface of the light guide or the exit side of the exit surface,
Light source device. The light source device according to claim 1,
The plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction orthogonal to the light emission axis,
The light source unit, the collimator, and the light guide are arranged in a second direction corresponding to the light emission axis,
The light guide body guides the light in the second direction incident from the incident surface in the second direction and emits the light from the emission surface,
A reflection mirror configured to reflect the light in the second direction in the third direction orthogonal to the first direction and the second direction on the emission side of the light guide;
Light source device. The light source device according to claim 1,
The plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction orthogonal to the light emission axis,
The light source unit and the collimator are arranged in a second direction corresponding to the light emission axis,
The light guide includes the incident portion having the incident surface on which light in the second direction from the collimator is incident, the light in the second direction incident from the incident surface, the first direction and the first light. A first reflecting portion having a first reflecting surface for reflecting in a third direction orthogonal to two directions, and a second reflecting having a second reflecting surface for reflecting the reflected light in the third direction in the second direction. And the emission part having the emission surface that emits the reflected light in the second direction,
Light source device. The light source device according to claim 1,
Comprising a polarization conversion element disposed on the output side of the collimator,
The plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction orthogonal to the emission axis,
The polarization conversion element extends in the first direction, and is disposed at a symmetrical position with respect to a plane formed by the first direction and a second direction corresponding to the emission axis. including,
Light source device. A head-up display device that projects image light to a display area of a windshield or combiner of a vehicle and provides a virtual image to a 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; and
An adjusting optical system including an optical element for guiding the image light to the display area of the windshield or the combiner while reflecting the image light;
With
The light source device
A light source unit including a plurality of semiconductor light source elements for generating light;
A collimator including a plurality of collimator elements disposed on the light-emitting axis of each of the plurality of semiconductor light source elements;
A light guide disposed on the exit side of the collimator;
With
The light guide includes an incident portion having an incident surface on which light on the light-emitting axis from the semiconductor light source element is incident, and an emitting portion having an output surface that emits the light, and the incident surface or the emission surface At least one of the surfaces has a free-form surface shape for realizing predetermined light distribution control,
Head-up display device. The head-up display device according to claim 11.
The normal direction of the display surface of the display element and the normal direction of the optical element form an angle of 10 ° or more with respect to the direction of the optical axis of the emitted light from the light source device.
Head-up display device. The head-up display device according to claim 12,
As the optical element of the adjustment optical system, a refractive element that refracts the image light from the display element, and one or more reflection mirrors that reflect the refracted light,
The normal direction of the refraction 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.
Head-up display device.

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