Light source device and head-up display device

Abstract

To provide a head-up display device which is small and light-weight, achieves high light utilization efficiency, and is modularized to be used as a planer light source, and to provide a light source device of the head-up display device.SOLUTION: A light source device includes at least: a semiconductor light source element which generates light; an optical element which performs predetermined processing to an outgoing beam from the semiconductor light source element; and a transparent material disposed between the semiconductor light source element and the optical element and including a light incident part into which the outgoing beam from the semiconductor light source element enters and a light emission part which emits the light entered from the semiconductor light source element to the optical element. The light incident part of the transparent material has a shape that corresponds to a light incident part of the optical element.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a light source device that is suitable for use in a head-up display device and that can be used as a planar light source using solid-state light-emitting elements. [Background technology]

[0002] With the remarkable development of solid-state light-emitting elements such as LEDs in recent years, lighting devices using such solid-state light-emitting elements as light sources have been widely used in various lighting fixtures as light sources that are small, lightweight, consume little power, and are environmentally friendly and have a long life.

[0003] Conventionally, according to, for example, the following patent documents, a semiconductor light source device having a simple configuration is already known as a light source device for a projector, which efficiently cools a semiconductor light emitting element to emit bright light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-33668 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the semiconductor light source device disclosed in the above-mentioned prior art (Patent Document 1) mainly provides a semiconductor element light source device that efficiently and brightly emits light by efficiently cooling the semiconductor light emitting element to prevent the element from shorting out and becoming non-functional, and the light emitted from the semiconductor element is focused using one or more lenses provided opposite the element. Therefore, although the prior art makes it possible to improve the light emission efficiency of the LED, which is a semiconductor light source, it is difficult to sufficiently focus and use the emitted light, and the light utilization efficiency characteristics and uniform illumination characteristics are still insufficient, particularly in projectors that require a high light emission performance, and further in head up displays (hereinafter referred to as "HUD") devices and vehicle headlamp devices, and there is still room for various improvements.

[0006] Therefore, an object of the present invention is to provide a head-up display device and a light source device that are small and lightweight and have high utilization efficiency of emitted light. [Means for solving the problem]

[0007] As one embodiment for achieving the above-mentioned object, according to the present invention, there is provided a light source device comprising a semiconductor light source element that generates light, an optical element that performs a predetermined processing on the light emitted from the semiconductor light source element, a light entrance portion that is arranged between the semiconductor light source element and the optical element and into which the light emitted from the semiconductor light source element is incident, and a light exit portion that emits the light incident from the semiconductor light source element to the optical element, wherein a light reflecting portion is provided between the light entrance portion and the light exit portion for converting the shape of the light entrance portion into a shape corresponding to the light entrance portion of the optical element, and the light source device comprises a plurality of light entrance portions into which the light emitted from the semiconductor light source element is incident. Effect of the Invention

[0008] The present invention has the excellent effect of providing a light source device and a head-up display device that are small and lightweight and have high utilization efficiency of emitted light. [Brief description of the drawings]

[0009] [Figure 1] 1 is an exploded perspective view showing an overall overview of a head-up display device including an image display device, as an example to which a light source device according to an embodiment of the present invention is applied; [Diagram 2] FIG. 2 is an exploded perspective view showing an overview of the internal configuration of the image display device. [Diagram 3] FIG. 2 is a perspective view showing an example of an internal configuration of a light source device. [Figure 4] 3 is a partially enlarged cross-sectional view showing the configuration and operation of a collimator and a polarization conversion element that constitute the light source device. FIG. [Diagram 5] FIG. 13 is a partially enlarged cross-sectional view showing a comparative example of the configuration of a collimator and a polarization conversion element. [Figure 6] FIG. 11 is a perspective view showing another example of the internal configuration of the light source device. [Figure 7] 2A and 2B are a side view and an enlarged cross-sectional view showing a composite diffusion block of the light source device, respectively. [Figure 8] 1A is an overall perspective view showing the details of a light guide constituting a light source device, a cross-sectional view thereof, and a partially enlarged cross-sectional view showing the details of the cross-section. [Figure 9] FIG. 2 is an enlarged schematic diagram showing a reflecting surface and a connecting surface for explaining a light guide body. [Figure 10] 1A and 1B are top and side views showing an enlarged reflective surface and a connecting surface for explaining a light guide body. [Figure 11] FIG. 13 is a side view showing a comparative example of a light guide. [Figure 12] FIG. 13 is a side view showing a modified example of the light guide. [Figure 13] FIG. 11 is a side view showing another modified example of the light guide. [Figure 14] FIG. 11 is a side view showing still another modified example of the light guide body. [Figure 15] FIG. 13 is a side view showing a modified example of a light guide using a functional scattering surface. [Figure 16] FIG. 13 is a diagram including characteristic curves explaining a functional scattering surface. [Figure 17]11A and 11B are diagrams for explaining the effect of a functional scattering surface. [Figure 18] 10A to 10C are diagrams for explaining an example of processing of a light guide body. [Figure 19] FIG. 11 is a perspective view showing the overall appearance of another example of an image display device to which a light source device is applied. [Figure 20] 13A and 13B show top and side views of a variation of the light guide for a larger liquid crystal display device. [Figure 21] 21 is a side view showing a modification of the light guide of FIG. 20. FIG. [Figure 22] 1A to 1C are top views showing specific examples of textures formed on the entrance surface or exit surface of a light guide. [Figure 23] FIG. 13 is an overall side view showing an example of the configuration of a larger light source device in which light guides are combined. [Figure 24] 1 is an overall side view showing an example of the configuration of a light source device including a light guide having a plurality of light entrance portions; [Diagram 25] 11A and 11B are top and side views showing an example of a configuration in which a light guide is formed by a polarization conversion element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the same parts are generally given the same reference numerals, and the repeated explanations are omitted. On the other hand, a part that has been described with a reference numeral in a certain drawing may be referred to with the same reference numeral in the explanation of another drawing, although it is not shown again.

[0011] FIG. 1 is an exploded perspective view showing an example in which a light source device according to an embodiment of the present invention, which will be described in detail below, is applied to a head-up display (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, which is a housing of the image display device 30, and a concave mirror 141 and a distortion correction lens 143 are stored inside the case. An opening through which image light is projected toward a windshield (not shown) is formed on the upper surface of the upper exterior case 151, and the opening is covered by an anti-glare plate 152 (glare trap). Reference numeral 142 in the figure indicates a concave mirror drive unit constituted by an electric motor for adjusting the position of the concave mirror 141.

[0012] In the HUD device 1 having such a configuration, it will be clear 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 a display distance adjustment mechanism and a mirror drive unit, not shown here. In addition, the display position of the virtual image seen by the driver may be adjusted in the vertical direction by adjusting the angle of the concave mirror 141 to adjust the position where the image is projected onto the windshield. The contents to be displayed as the virtual image are not particularly limited, and for example, vehicle information, navigation information, and an image of the scenery ahead captured by a camera image (such as a surveillance camera or an around viewer) not shown in the figure can be appropriately displayed.

[0013] Next, the above-mentioned image display device 30 will be described in detail below with reference to Fig. 2. The image display device 30 is configured by housing LED elements, a collimator, a composite diffusion block, a light guide, and the like, which will be described in detail later, inside a light source device case 11 formed of, for example, plastic or the like. A liquid crystal display element (LCD) 50 is attached to the upper surface of the image display device 30, and an LED board 12 on which LED (Light Emitting Diode) elements, which are semiconductor light sources, and their control circuits are mounted is attached to one side of the LCD. Furthermore, a heat sink (heat dissipation fin) 13 for cooling heat generated by the LED elements and the control circuit is attached to the outer side of the LED board 12.

[0014] In addition, in the above-mentioned image display device 30, the liquid crystal display element 50 attached to the upper surface of the light source device case 11 is composed of a liquid crystal display panel frame 51, a liquid crystal display panel 52 attached to the frame, and an FPC (flexible wiring board) 53 electrically connected to the panel.

[0015] As is clear from the above description, for example, in the case of a HUD device, because it is incorporated into a small space such as the dashboard of a vehicle, it is preferable that the image display device 30 including the light source device according to the embodiment of the present invention constituting the HUD device 1 is modularized to be small, highly efficient, and suitably usable.

[0016] 3 shows the configuration of an optical system with a polarization function as an example of an optical system housed inside the image display device 30, i.e., in the case 11 of the light source device. That is, a plurality of (two in this example) LEDs 14a and 14b constituting the light source according to the embodiment of the present invention are attached at predetermined positions with respect to an LED collimator 15.

[0017] Incidentally, on the light emission side of the LED collimator 15, a polarization conversion element 21 is provided, which is made of optical members such as a polarizing beam splitter and a phase plate, and is arranged symmetrically with respect to the central axis of the LED collimator 15, as described in detail below. Furthermore, on the emission side of the polarization conversion element 21, a rectangular synthesis diffusion block 16 is provided. That is, the light emitted from the LED 14a or 14b is converted into parallel light by the action of the LED collimator 15 and enters the polarization conversion element 21, and is converted into a desired polarized light by the polarization conversion element 21, and then enters the synthesis diffusion block 16.

[0018] Furthermore, on the exit surface side of the composite diffusion block 16, as an example, a light guide 17 having a substantially triangular cross section is provided via a first diffusion plate 18a, as shown in Fig. 3, and a second diffusion plate 18b is attached to its upper surface. As a result, the horizontal light of the LED collimator 15 is reflected upward in the figure by the action of the light guide 17, and is guided to the entrance surface of the liquid crystal display element 50. At that time, the intensity of the light is made uniform by the first and second diffusion plates 18a and 18b.

[0019] Next, the main components constituting the light source device according to the embodiment of the present invention described above will be described below, including details of each part.

[0020] As shown in Fig. 4, the light source device according to the embodiment of the present invention is composed of LED elements 14a and 14b, which are single or multiple semiconductor light emitting elements, formed on an LED substrate 12, and an LED collimator 15 arranged opposite to the light emitting surface of the element. The LED collimator 15 is formed of a resin having excellent heat resistance and translucency, such as polycarbonate, and is formed on the LED substrate 12 so as to surround the LED element 14 as the center, as shown in Fig. 4. More specifically, the LED collimator 15 has a conical outer peripheral surface 156 obtained by rotating a substantially parabolic cross section, and a recess 153 having a predetermined curved surface is formed at the top of the LED collimator 15, which is the light incident side, and the LED elements 14a and 14b are arranged in the substantially central portion of the recess. The parabolic surface (reflector portion) forming the conical outer peripheral surface 151 of the LED collimator 15 is set, together with the curved surface of the recess 153, so that the light emitted from the LED elements 14a, 14b in the peripheral direction and entering the inside of the LED collimator through the air in the recess 153 is incident within the range of angles at which the light is totally reflected by the parabolic surface. In this way, by utilizing the total reflection on the parabolic surface, a process such as forming a metal reflective film on the outer peripheral surface of the LED collimator is not required, and therefore the device can be manufactured more inexpensively.

[0021] In addition, an entrance surface (lens surface) 157 having a predetermined curved surface is formed in the center of the recess 153 of the LED collimator 15, and together with a convex portion (lens surface) 158 formed on the opposing surface (exit surface) 154, it forms a so-called convex lens having a light collecting effect. The convex portion 158 may be formed as a flat surface or a concave lens surface recessed inward. That is, the LED collimator 15 has a function of a collecting lens that collects light emitted from the LED collimator 15 to the exit surface side in the center of its conical outer shape, and also has a function of collecting light emitted from the LED elements 14a and 14b in the peripheral direction and guiding it to the exit surface side in the outer peripheral surface 156 (reflector portion).

[0022] As shown in FIG. 4, the LED substrate 12 is disposed and fixed to the LED collimator 15 such that the LED elements 14a, 14b on the surface of the LED substrate 12 are positioned in the center of the recess 153 thereof.

[0023] According to this configuration, among the light emitted from the LED elements 14a and 14b, particularly the light emitted from the center toward the emission optical axis (to the right in the figure) is collected by the two convex lens surfaces 157 and 158 that form the outer shape of the LED collimator 15 as shown by the arrows in the figure by the above-mentioned LED collimator 15 to become parallel light, and the light emitted from other parts toward the periphery is reflected by the parabolic surface that forms the conical outer circumferential surface (reflector part) 156 of the LED collimator 15, and is similarly collected and becomes parallel light. In other words, according to the LED collimator 15 that has a convex lens in its center and a parabolic surface formed in its periphery, it is possible to extract almost all of the light generated by the LED elements 14a and 14b as parallel light, and it is possible to improve the utilization efficiency of the generated light.

[0024] In this embodiment, a polarization conversion element 21 made of optical members such as a polarizing beam splitter and a phase plate is provided on the light emission side of the LED collimator 15, and as is clear from the figure, these elements are arranged symmetrically with respect to the central axis of the LED collimator (see the dashed line in the figure). Furthermore, a rectangular synthetic diffusion block 16 is provided on the emission side of the polarization conversion element. That is, the light emitted from the LED element 14a or 14b is converted into parallel light by the action of the LED collimator 15 and enters the synthetic diffusion block 16.

[0025] Thus, according to this configuration, as is clear from the comparison with the comparative example in Fig. 5, the light source device can be made smaller in size by realizing a lower cost due to a thinner structure and a reduced amount of material used. 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 light beam transmitted through it, so that a difference in the shape of the light beams due to the optical path length difference is unlikely to occur, and is therefore effective in eliminating non-uniformity in the luminance distribution caused by differences in the shape of the light beams, particularly in a system using multiple light sources and LED collimators.

[0026] 6 shows another example of the configuration of the optical system housed inside the image display device 30, i.e., in the case 11 of the light source device. That is, a plurality of (four in this example) LED elements 14a, b, c, and d constituting the light source according to the embodiment of the present invention are attached at predetermined positions relative to the LED collimator 15.

[0027] In this embodiment, a rectangular synthetic diffusion block 16 is provided on the light output side of the LED collimator 15, but the above-mentioned polarization conversion element 21 is not provided. Therefore, the light emitted from the LED elements 14a, b, c, and d is not polarized, but is converted into parallel light by the action of the LED collimator 15 and enters the synthetic diffusion block 16.

[0028] Furthermore, on the exit surface side of the composite diffusion block 16, as shown in Fig. 6 for example, a light guide 17 having a substantially triangular cross section is provided via a first diffusion plate 18a, and a second diffusion plate 18b is attached to its upper surface. As a result, the horizontal light of the LED collimator 15 is reflected upward in the figure by the action of the light guide 17, and is guided to the entrance surface of the liquid crystal display element 50. At that time, the intensity is made uniform by the first and second diffusion plates 18a and 18b, as in the above example.

[0029] Next, the combining / diffusion block 16, which is another component of the image display device 30, will be described with reference to Fig. 7. Fig. 7(a) shows a side view of the combining / diffusion block 16, and Fig. 7(b) shows an enlarged cross-sectional view of a portion of the combining / diffusion block 16.

[0030] In the composite diffusion block 16 formed of a translucent resin such as acrylic, as is clear from Figs. 7(a) and (b), a large number of textures 161 having a substantially triangular cross section are formed at a pitch S on the exit surface, and the textures 161 diffuse the light emitted from the LED collimator 15 in the vertical direction of the light guide light incident portion (surface) 171 of the light guide 17 described below. The interaction between the substantially triangular textures 161 and the diffusion plates 18a and 18b described below makes it possible to uniformize the intensity distribution of the light emitted from the exit portion 173 of the light guide 17 even if the LED collimators 15 are discretely arranged. In addition, in the head-up display device, the display position of the virtual image seen by the driver can be adjusted by adjusting the angle of the concave mirror 141 as described above, but there is generally no function for adjusting the left and right position, and the confirmation of the virtual image is premised on binocular vision, so it is desirable that the area in which the virtual image can be viewed is wider in the left and right directions than in the up and down directions. 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-back direction. In this configuration, the direction in which the light is diffused by the texture 161 of the composite diffusion block and the orientation angle becomes wider is set to the left-right direction of the virtual image display, thereby widening the area in which the virtual image can be recognized in the left-right direction.

[0031] In particular, the above-mentioned texture 161 limits the light diffusion direction to the side surface of the light guide, and furthermore, makes it possible to control the diffusion in the side surface direction, thereby making it possible to weaken the isotropic diffusion of the first and second diffusion plates 18a, 18b, thereby improving the light utilization efficiency and realizing a light source device with good characteristics. Note that in this example, an example of the substantially triangular texture 161 is shown, with an angle γ of 30 degrees and a formation pitch S of 0.5 mm.

[0032] <Light guide> Next, the light guide 17 constituting the image display device 30 will be described in detail below with reference to Fig. 8. The light guide 17 has a function of internally reflecting and refracting the light received from the light source device described above as parallel light through an incident surface, guiding the light in a desired direction, and extracting the light as planar light having a desired area.

[0033] FIG. 8(a) is a perspective view showing the whole of the light guide 17, FIG. 8(b) is a cross-section thereof, and FIGS. 8(c) and (d) are partially enlarged cross-sectional views showing the details of the cross-section.

[0034] The light guide 17 is a member formed, for example, from a translucent resin such as acrylic with a substantially triangular cross section (see Figure 8(b)), and, as is clear from Figure 8(a), is provided with a light guide light incident portion (surface) 171 facing the exit surface of the synthetic diffusion block 16 via a first diffusion plate 18a, a light guide light reflecting portion (surface) 172 forming an inclined surface, and a light guide light exit portion (surface) 173 facing the liquid crystal display panel 52 of the liquid crystal display element 50 via a second diffusion plate 18b.

[0035] 8(c) and (d), which are partially enlarged views, a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape on the light guide light reflecting portion (surface) 172 of the light guide 17. The reflective surface 172a (a line segment sloping upward to the right in the figure) forms an angle αn (n: natural number, for example, 1 to 130 in this example) with the horizontal plane indicated by the dashed line in the figure, and as an example, αn is set to 43 degrees or less (but 0 degree or more) here.

[0036] On the other hand, the connecting surface 172b (a line segment slanting downward to the right in the figure) forms βn (n: natural number, for example, 1 to 130 in this example) with respect to the reflecting surface. That is, the connecting surface 172b of the reflecting part is inclined at an angle that casts 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, α1, α2, α3, α4 ... form the elevation angle of the reflecting surface, and β1, β2, β3, β4 ... form the relative angle between the reflecting surface and the connecting surface, which is set to 90 degrees or more (but 180 degrees or less) as an example. In this example, β1 = β2 = β3 = β4 = ... = β22 = ... β130.

[0037] 9 and 10 are schematic diagrams in which the size of the reflection surface 172a and the connection surface 172b is enlarged relative to the light guide 17 for the purpose of explanation. In the light guide light incident portion (surface) 171 of the light guide 17, the main light ray is deflected by δ in a direction in which the angle of incidence with respect to the reflection surface 172a becomes larger (see FIG. 10(b)). That is, the light guide light incident portion (surface) 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the emission surface of the synthetic diffusion block 16 is diffused and incident via the first diffusion plate 18a, and as is clear from the figures, it reaches the light guide light reflection portion (surface) 172 while being slightly bent (deflected) upward by the light guide light incident portion (surface) 171 (compare with the example of FIG. 11).

[0038] In addition, in this light guide light reflection part (surface) 172, a large number of reflection surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape, and the diffused light is totally reflected on each reflection surface 172a and directed upward, and further passes through the light guide light emission part (surface) 173 and the second diffusion plate 18b and enters the liquid crystal display panel 52 as parallel diffused light. Therefore, the reflection surface elevation angles α1, α2, α3, α4... are set so that each reflection surface 172a is an angle equal to or greater than the critical angle with respect to the diffused light, while the relative angles β1, β2, β3, β4... between the reflection surface 172a and the connecting surface 172b are set to a certain angle as described above, and more preferably, to an angle of 90 degrees or more (βn≧90°), the reason for which will be described later.

[0039] With the above-mentioned configuration, each reflecting surface 172a is always at an angle equal to or greater than the critical angle with respect to the diffused light, so that total reflection is possible without forming a reflective film such as a metal film on the light guide light reflecting portion 172, and a light source device having a light guide that can guide light in a desired direction and extract light in a planar shape having a desired area can be realized at low cost. On the other hand, as shown in Fig. 11 as a comparative example, if there is no bending (polarization) of the main light ray at the light guide entrance portion of the light guide 17, part of the diffused light becomes at an angle equal to or less than the critical angle with respect to the reflecting surface 172a, and sufficient reflectance cannot be ensured, so that a light source device with good characteristics (brightness), i.e., an image display device, cannot be realized.

[0040] However, according to the shape of the light guide light reflecting portion (surface) 172 of the light guide 17 described above, the total reflection condition of the main light can be satisfied, and there is no need to provide a reflective film such as aluminum on the light guide light reflecting portion 172, making it possible to efficiently reflect light, and there is no need for a vapor deposition process of an aluminum thin film that increases manufacturing costs, making it possible to realize a brighter light source at a lower cost. Also, each relative angle β is set to an angle such that the connecting surface 172b casts a shadow on the main light ray L30 against the light diffused by the composite diffusion block 16 and the diffusion plate 18a. This makes it possible to reduce the reflection of the unnecessary light by suppressing the incidence of the unnecessary light on the connecting surface 172b, and to realize a light source device with good characteristics.

[0041] According to the above-mentioned light guide 17, as shown in FIG. 9, the length of the light guide light output portion (surface) 173 in the optical axis direction can be freely changed by appropriately setting the length and ratio of the connecting surfaces Lc1, Lc2, Lc3, . . . and the reflecting surfaces Lr1, Lr2, Lr3, . . . , so that it is possible to realize a light source device in which the size (surface size) of the light guide light output portion (surface) 173 can be appropriately changed to a necessary size (surface size) suitable for the device such as the liquid crystal display panel 52 with respect to the light guide light input portion (surface) 171. This also means that the light guide light output portion (surface) 173 can be made into a desired shape regardless of the arrangement shape of the LED elements 14a, 14b constituting the light source, that is, a planar light source having a desired shape can be obtained. Furthermore, it also leads to securing the degree of freedom in design including the arrangement of the LED elements 14a, 14b constituting the light source, which is advantageous for miniaturization of the entire device.

[0042] Fig. 12 shows the above-mentioned modified example. As is clear from the figure, in this modified example, the light guide light incident portion (surface) 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 an auxiliary light guide 17a having a vertical triangular cross section is provided on the incident surface to slightly bend (deflect) the incident light upward. Furthermore, Fig. 13 shows another modified example in which the light guide light incident portion (surface) 171 of the light guide 17 is a vertical plane, and the LED collimator 15 is slightly inclined, thereby slightly bending (deflecting) the incident light upward. That is, the same effect as the above can be obtained by these modified examples.

[0043] 14, by appropriately setting the connecting surface 172b constituting the light guide light reflecting portion (surface) 172 (in this example, the light is not reflected by a part of the reflecting surface 172a in the center), it is possible to greatly change the ratio Lr / Lc of the reflecting surface 172a and the connecting surface 172b in the light guide light emitting portion (surface) 173 of the light guide 17 depending on the location. As a result, in the illustrated example, the light emitted from the light guide light emitting portion (surface) 173 of the light guide 17 is shown to be divided into left and right in the direction of the optical axis. Such a configuration would be suitable, for example, in the case where the illumination light from the HUD device is separated into up and down or left and right without loss. Also, by appropriately adjusting the ratio Lr / Lc, it is possible to partially strengthen or weaken the reflected light.

[0044] In addition, in the above-mentioned light guide 17, as shown in Figure 15, it is possible to omit either or both of the diffusion plates 18a, 18b also shown in Figure 6 by providing (forming) a functional scattering surface described below on at least one of the light guide light entrance portion (surface) 171 and the light guide light exit portion (surface) 173.

[0045] This functional scattering surface aims to reduce unnecessary divergence components by reducing the surface roughness of high spatial frequency components (fine components). Figure 16(b) shows the surface roughness spatial frequency components of a normal scattering surface, while Figure 16(a) shows the surface roughness spatial frequency components of a scattering surface with more preferable scattering properties. In this figure, the solid line shows the surface roughness spatial frequency components when measured in a direction perpendicular to the paper surface of the entrance or exit surface of the light guide in Figure 15, and the wavy line shows the surface roughness spatial frequency components when measured in a direction parallel to the paper surface of the entrance or exit surface of the light guide in Figure 15.

[0046] The surface roughness spatial frequency distribution of a normal scattering surface, as shown in FIG. 16(b), shows a distribution along the reciprocal of the spatial frequency (1 / f). In contrast, a more preferable surface roughness spatial frequency distribution, as shown in FIG. 16(a), shows low values ​​in the low frequency range of spatial frequencies of 10 / mm or less and high frequency ranges of 100 / mm or more, and since there are few low frequency components of the surface roughness spatial frequency and a moderate amount of mid frequency components, a light source with less scattering unevenness can be realized. In addition, since there are few high frequency components of the surface roughness spatial frequency, the scattering angle of the scattered light does not become large, and unnecessary components are reduced, so a light source with a bright and uniform luminance distribution can be realized. In order to realize such characteristics, the functional scattering surface further has been confirmed by experiments that, particularly when the spatial frequency components in the high frequency range of 100 / mm or more are set to 10 nm or less, unnecessary scattering components can be prevented from occurring in the visible light range (wavelength 400 nm or more). In contrast, a normal scattering surface, as shown in FIG. 17(b), scatters light in directions other than those that can be used as a light source, so it is not possible to realize a bright light source.

[0047] In addition, within the above range, the scattering angle can be adjusted by adjusting the spatial frequency components as shown by the solid and wavy lines in Figure 16(a). As described above, it is desirable for the area in which the virtual image can be viewed in the head-up display device to be wider in the left-right direction than in the up-down direction, so the scattering angle was adjusted so that the orientation angle of the light source device is wider in the corresponding direction. Specifically, the spatial frequency distribution of the surface roughness measured in the vertical direction to the paper surface of the entrance surface and the exit surface of the light guide shown in Figure 15 is the distribution shown by the solid line in Figure 16(a), and the spatial frequency distribution of the surface roughness measured in the direction perpendicular to that, i.e., along the paper surface, is a distribution with relatively fewer high-frequency components than the solid line, as shown by the wavy line in the same figure.

[0048] By adopting the above-mentioned functional scattering surface, the degree of freedom in controlling the incidence and emission of light at the entrance and exit surfaces of the light guide 17 is increased, thereby reducing unevenness in the brightness of the light from the light source device and enabling fine control according to the characteristics of the optical system device (in this example, liquid crystal display element 50 as an example) located downstream, which will also be advantageous in reducing the cost of the device.

[0049] In addition, as shown in FIG. 15, the incident surface of the light guide 17 is shaped such that the curvature of the upper end 171a and the lower end 171b is larger than that of the center 171c in the cross section of the plane parallel to the incident light and the emitted light to the light guide. This is effective when using an LED 14 having a relatively large light-emitting part as shown in FIG. 15. That is, the light emitted from the center of the LED 14 is converted into parallel light by the LED collimator 15 as shown by the light rays L30c, L30a, and L30b indicated by solid lines, but the light emitted from the upper end and the lower end of the LED becomes diffuse light rather than parallel light as shown by the light rays L30d and L30e indicated by the dashed lines. In order to convert the light into parallel light, it is necessary to make the curvature of the light guide incident surface larger than that of the center 171c as shown by 171a and 171b. By adopting the above configuration, a light source device with good characteristics can be realized even when a relatively large LED is used.

[0050] As described above, β1=β2=β3=β4...βn≧90° is set because, as shown in FIG. 18, in machining the mold 40 for manufacturing the light guide 17 by injection molding, the reflecting surface 172b and the connecting surface 172b can be machined simultaneously by an end mill having a relative angle β between the bottom surface and the side surface. Also, since the reflecting surface 172a and the connecting surface 172b can be machined by a relatively thick tool, the machining time can be significantly shortened and the machining cost can be significantly reduced. Also, the boundary edge between the reflecting surface 172a and the connecting surface 172b can be machined with high precision, and the light guide characteristic of the light guide 17 can be improved.

[0051] 19 is a perspective view of the overall appearance of an image display device 30 showing another example of an image display device 30 to which the above-mentioned light source device is applied, and although details are not shown in this embodiment, the heat generated in the LED substrate 12 is cooled by a heat sink 13c arranged at the bottom of the device through a heat transfer plate 13d. With this configuration, a light source device with a short overall length is realized.

[0052] Further, a further embodiment (Example 2) of the light source device according to the above-mentioned embodiment of the present invention is shown below. Fig. 20 shows a light source device for a larger liquid crystal display device in which the LED elements 14, which are solid-state light sources, are arranged in 3 pieces x 2 rows, as compared with the above-mentioned embodiment. In the light source device according to Example 2, when the light guide 17 is produced by injection molding, the light guide light entrance portion (surface) 171 becomes thick, which increases the cooling time in the molding die, and in order to prevent this from increasing the molding tact time and increasing costs, a part (upper part of the figure) of the light guide light entrance portion (surface) 171 is removed.

[0053] FIG. 21 shows a light source device for a larger liquid crystal display device in which the LED elements 14, which are solid light sources, are arranged in 3 pieces x 2 rows, similarly to the light source device of the above-mentioned embodiment 2. In this example, a part of the light guide light incident portion (surface) 171 is removed, and the tip portion (the right part in the figure) of the light guide 17 is thickened, thereby making it possible to uniformize the cooling speed during molding and to perform molding with higher accuracy. In this example, the light guide 17 is configured so that the tip portion is thickened so that the main light beam is incident on the liquid crystal panel 55 with an incident angle tilted by a predetermined angle η. This is because, in general, it is desirable that the inclination of the main light beam incident on the liquid crystal display panel is close to vertical. However, some commercially available liquid crystal panels have better characteristics when the incident angle is tilted by about 5 to 15 degrees depending on the characteristics, and the incident light is incident on the liquid crystal display panel with an angle η of 5 to 15 degrees tilted depending on the characteristics.

[0054] Furthermore, Fig. 22 is a top view showing a specific example of the above-mentioned texture 175 formed on the incident surface or the exit surface of the light guide 17 also shown in Fig. 15. In this schematic diagram, Fig. 22(a) shows an example in which the boundary between the reflecting surface (or exit surface) and the connecting surface is arranged and formed in a straight line, and Fig. 22(b) shows another example in which the boundary is arranged and formed in a curved line depending on the necessity, for example, when the LED elements 14a, 14b, which are light sources, are arranged separately and dispersed from each other.

[0055] <Other configuration examples of the light source device> The above describes an example of a light source device according to an embodiment of the present invention, particularly, a light source device applied to a head-up display (HUD) device 1. Below, however, an example including further configurations of the light source device will be described.

[0056] 23 shows an example in which a plurality of light source devices (two in this example) including the above-mentioned LED elements 14a, 14b and light guide 17 are combined so that their light guide light emitting parts (surfaces) 173 are on the same plane, corresponding to a larger liquid crystal display panel 52. Note that such a combined structure makes it possible to realize an image display device equipped with light guide light emitting parts (surfaces) 173 of even more types of surface sizes and light amounts.

[0057] 24 shows a light source device further comprising a light guide 17' having a plurality of (two in this example) light guide light incidence parts (surfaces) 171a, 171b, and as is clear from the figure, light guide light incidence parts (surfaces) 171a, 171b are formed on both side surfaces of the light guide 17', into which light from a light source constituted by LED elements 14a, 14b, collimator 15, etc. is incident, and parallel light incident from the light guide light incidence parts (surfaces) 171a, 171b is refracted and guided to a light guide light reflection part 172 formed on the bottom of the light guide 17' in this example. The surface of the light guide light reflection part 172 has a wavy cross section and is further provided with a reflective film (aluminum film) that reflects light. According to this, the parallel light incident from the light guide light incident portions (surfaces) 171a, 171b is reflected by the light guide light reflecting portion 172, as shown by the arrows in the figure, and directed toward the upper part of the light guide 17', and is emitted from the light guide light exit portion (surface) 173 toward a device such as the above-mentioned liquid crystal display panel 52.

[0058] With the light source device having such a configuration, it is relatively easy to deal with the increase in size of the liquid crystal display device that emits light, that is, it is possible to realize a light source device with a larger emission surface. As is clear from the above, the light source device can be realized using a relatively thin light guide 17', so that the device can be made thinner. In addition, the thickness of the light guide 17' is almost uniform, and its moldability is good.

[0059] In addition, in the light guide 17′, the light incident from the light guide light entrance portions (surfaces) 171a and 171b is reflected and refracted inside the light guide, and the light is emitted from the light guide light exit portion (surface) 173 to an external device (in this example, a liquid crystal display panel which is a downstream optical device). IN is generally expressed as the area S of the light exit surface. OUT Greater than (S IN >S OUT ) is set, and further, the shape of the light guide 17' can be formed to match the size and shape of the LED, which is the light emitting element.

[0060] Furthermore, as shown in FIG. 25, the light guide 17" arranged behind the synthetic diffusion block 16 can also be formed of a polarization conversion element 21'. In this configuration, as is clear from the figure, a triangular prism-shaped light-transmitting member 211' and a parallelogram-shaped light-transmitting member 212' that constitute the polarization conversion element 21' are combined, and a PBS film 211 is formed at the boundary between them, which reflects S-polarized light (see the symbol (x) in the figure) of the incident light that is emitted from the LED element 14a and collimated by the LED collimator 15, but transmits P-polarized light (see the up and down arrows in the figure). In addition, a 1 / 2λ phase plate 213 is formed on the top surface of the parallelogram-shaped light-transmitting member 212', and a reflective film 212 is formed on its side.

[0061] As is apparent from the figure, according to the above-described configuration, the incident light emitted from the LED element 14a and converted into parallel light by the LED collimator 15 is polarized into S-polarized light by the action of the polarization conversion element 21' constituting the light guide 17", and is emitted upward from the upper surface of the element. That is, in the above-described configuration, particularly by forming the light guide 17" with the polarization conversion element 21', it is possible to achieve a significant reduction in the size of the device and a significant reduction in the manufacturing costs of the device.

[0062] In the above description, the light source device according to the embodiment of the present invention is mainly applied to the image display device 30 of the HUD device 1. However, the light source device according to the embodiment of the present invention is not limited to this application, and may be applied, for example, as a light source device constituting a light source including a headlight device for a vehicle.

[0063] As is clear from the above detailed description, the light source device of the embodiment of the present invention has the function of concentrating the emitted light, making its intensity uniform, and directing it in the desired direction, regardless of the arrangement shape of the LEDs that make up the light source, and emitting planar light having the desired shape and area corresponding to the light incident surface of an output device such as a liquid crystal display device. This makes it possible to ensure a large degree of freedom in the design of an image display device including a light source device, and is advantageous in that, in addition to modularizing and miniaturizing the entire device, it is possible to efficiently utilize the emitted light, thereby providing a device that consumes low power and is environmentally friendly.

[0064] The light source device according to various embodiments of the present invention has been described above. However, the present invention is not limited to only the above-mentioned embodiments, and various modified examples are included. For example, the above-mentioned embodiments are detailed descriptions of the entire system in order to easily explain the present invention, and are not necessarily limited to those having all of the described configurations. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0065] 1...head-up display (HUD) device, 30...image display device, 141...concave mirror, 50...liquid crystal display element, 52...liquid crystal display panel, 12...LED substrate, 13...heat sink (heat dissipation fin), 14, 14a...14d...LED element, 15...LED collimator, 156...outer periphery (reflector portion), 153...entrance portion (concave portion), 157...entrance surface (lens surface), 1 54...exit surface, 158...exit side lens surface, 16...synthetic diffusion block, 16b...orientation control plate, 17...lightguide, 171...light guide light incident portion (surface), 172...light guide light reflecting portion (surface), 172a...reflecting surface, 172b...connecting surface, 173...light guide light exit portion (surface), 18a, 18b...diffuser plate, 21...polarization conversion element, 211...PBS film, 212...reflecting film, 213...1 / 2λ phase plate.

Claims

1. A semiconductor light source element that generates light; A diffusion element having a function of diffusing light emitted from the semiconductor light source element; an optical element including a light incident portion into which the light emitted from the diffusion element is incident, a reflecting portion that reflects the light incident from the light incident portion, and a light exit portion that emits the light reflected from the reflecting portion; and an image light display device that receives the light emitted from the optical element and generates a predetermined image light, the reflecting portion of the optical element is provided between the light incident portion and the light exit portion, the light incident portion of the optical element is formed in a curved shape, and the light from the semiconductor light source element is deflected by the light incident portion of the optical element, and is then reflected by the reflecting portion while satisfying a total reflection condition, so that the light is emitted to the image light display device disposed in a direction different from the direction of the light incident; The reflecting portion is provided with a reflecting surface in which each reflecting surface and each connecting surface are alternately formed in a sawtooth shape, The relative angle between the reflecting surface and the connecting surface is constant regardless of the location, The relative angle is set at an angle such that the connecting surface is a shadow of the main light with respect to the light diffused by the diffusion element, When the lengths of the reflective surface and the connecting surface projected in a normal direction with respect to the emission direction of the reflective surface are Lr and Lc, respectively, the ratio of the lengths Lr / Lc varies depending on the location, The light source device is characterized in that there are a plurality of light entrance portions, and a plurality of light exit portions corresponding to the plurality of light entrance portions are arranged to be on the same plane.

2. 2. The light source device according to claim 1, The light source device, wherein a reflective film is formed on the reflective portion.

3. A head-up display device using the light source device according to claim 1 or 2.

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