Video display device and head-up display equipped with a video display device, mobile device

Abstract

This image display device comprises: a light source unit (23) having a light source element (41) that emits light; a display panel that displays an image, and a light guide panel (25) that guides light from the light source unit (23) to the display panel. The light guide panel (25) has a collimating lens part (65) for collimating light from the light source unit (23) on an incident surface (43) where light from the light source unit (23) is incident. The maximum spread angle θ at which light emitted from the light source unit (23) intersects a main surface (65b) of the collimating lens part (65) is 15-60 degrees. The width of the light emitted from the light source unit (23) is less than 1 / 3 of the width (W2) of the main surface (65b) of the collimating lens part (65).

Description

Technical Field

[0001] The present disclosure relates to a video display device using a light guide plate, a head-up display equipped with this video display device, and a moving body.

Background Art

[0002] Patent Document 1 guides the light rays emitted from a light source to a display panel using a light guide plate. The light emitted from the light guide plate is incident on the display panel with the light distribution angle changed in the long side direction and the short side direction of the display panel by a light ray control unit and a light ray polarization member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an eyebox where an observer can visually recognize a virtual image, light must be diffused in the long side direction. However, if light is also diffused in the short side direction in accordance with the long side direction, the luminance in the short side direction will decrease. Since the light distribution angle is changed between the long side direction and the short side direction, the light distribution angle in the short side direction is smaller than that in the long side direction, but there remains an amount of light that spreads beyond the range of the eyebox.

[0005] [[ID=URL]] The present disclosure aims to provide a video display device with an increased amount of light in the eyebox, a head-up display equipped with this video display device, and a moving body.

Means for Solving the Problems

[0006] The image display device in this disclosure comprises a light source unit having a light source element that emits light, a display panel that displays an image, and a light guide panel that guides light from the light source unit to the display panel. The light guide panel has a collimating lens portion on the incident surface into which light from the light source unit is incident, which collimates the light from the light source unit. The maximum divergence angle θ at which the light emitted from the light source unit intersects the main surface of the collimating lens portion is 15 degrees or more and 60 degrees or less. The width of the light emitted from the light source unit is less than 1 / 3 of the width of the main surface of the collimating lens portion.

[0007] The head-up display in this disclosure includes the video display device described above.

[0008] The mobile device in this disclosure is equipped with the head-up display described above. [Effects of the Invention]

[0009] This allows us to provide a video display device with increased light intensity in the eyebox, a head-up display equipped with the video display device, and a mobile device. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram of a vehicle equipped with a head-up display according to Embodiment 1. [Figure 2] A schematic diagram of a cross-section of the video display device in Embodiment 1. [Figure 3] A schematic diagram of the video display device in Embodiment 1, viewed from the top. [Figure 4A] A partially enlarged cross-sectional view of the vicinity of the light source in Embodiment 1. [Figure 4B] A cross-sectional view showing the configuration of the light source unit in Embodiment 1. [Figure 5A] A cross-sectional view showing the pupil diameter of the light emitted from the light source element. [Figure 5B] An explanatory diagram showing the eyebox in Embodiment 1. [Figure 6] A diagram showing the illuminance distribution of the eye box in Embodiment 1. [Figure 7]Partial enlarged view near the light source element in the comparative example. [Figure 8] Diagram showing the illuminance distribution of the eye box in the comparative example. [Figure 9] Schematic diagram of a partial cross-section of the light guide panel in a modification of Embodiment 1. [Figure 10] Schematic diagram of a cross-section of the video display device in Embodiment 2. [Figure 11] Partial enlarged cross-sectional view of the video display device in Embodiment 2. [Figure 12] Partial enlarged cross-sectional view of the video display device in Modification 1 of Embodiment 2. [Figure 13] Partial enlarged cross-sectional view of the video display device in Modification 2 of Embodiment 2. [Figure 14] Partial enlarged cross-sectional view of the video display device in Modification 3 of Embodiment 2. [Figure 15] Partial enlarged cross-sectional view of the video display device in Modification 4 of Embodiment 2.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, detailed descriptions that are more than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art.

[0012] Note that the inventor(s) provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and do not intend to limit the subject matter described in the claims thereby.

[0013] (Embodiment 1) Hereinafter, the video display device according to the present embodiment of the present disclosure will be described with reference to FIGS. 1 to 8.

[0014] [1-1. Outline] Figure 1 is a schematic diagram of a vehicle 1 equipped with a head-up display 11 in this embodiment. The vehicle 1, as a moving object, is, for example, an automobile. A driver, for example, is a passenger in the vehicle 1 as an observer Da. The vehicle 1 is equipped with a windshield 3, i.e., a windshield, as a transparent member.

[0015] Light emitted from the display panel 31 of the head-up display 11 is guided through the windshield 3 into the observer Da's eye box Db. This allows observer Da to see the virtual image Iv. The eye box Db is the area in which observer Da can see the virtual image without any loss of detail.

[0016] [1-2. Structure] [1-2-1. Head-up display configuration] The head-up display 11 comprises an image display device 21 and a reflective optical unit 13. The head-up display 11 is housed within a housing 15. In Figure 1, the head-up display 11 and housing 15 are shown enlarged for easier understanding. The configuration of the image display device 21 will be described later.

[0017] The reflective optical unit 13 includes a first mirror 17 and a second mirror 19. The first mirror 17 reflects light emitted from the display panel 31 of the video display device 21 (described later) toward the second mirror 19. The second mirror 19 reflects light from the first mirror 17 toward the windshield 3. The reflective surface of the second mirror 19 has a concave shape. The reflective optical unit 13 does not necessarily have to consist of two mirrors. The number of mirrors may be one or three or more. In addition, the reflective optical unit 13 may have refractive optical systems such as lenses in the optical path.

[0018] The housing 15 has an opening 16. The opening 16 may be covered with a transparent cover.

[0019] [1-2-2. Configuration of the video display device] The configuration of the video display device 21 of Embodiment 1 will be described below using Figures 2 and 3. Figure 2 is a schematic cross-sectional view of the video display device 21 in Embodiment 1. This cross-section is an XZ cross-section. Figure 3 is a schematic plan view of the video display device 21 in Embodiment 1. In each figure, the Y-axis direction is the first direction and is the direction of the short side of the display panel 31, the X-axis direction is the second direction and is the direction of the long side of the display panel 31, and the Z-axis direction is the direction perpendicular to the ZY plane.

[0020] The image display device 21 comprises a light source unit 23 that emits light, a light-gathering lens 24, a light guide panel 25, a specular reflective member 27 as a reflective member, a light ray direction changing member 29, an alignment lens 30, and a display panel 31 that displays an image.

[0021] The light source unit 23 comprises a plurality of light source elements 41. The plurality of light source elements 41 are arranged in a line in a first direction (Y-axis direction) relative to the image display device 21. The light source elements 41 have light-emitting elements 41a (see Figure 4B) that supply illumination light to the transmissive display panel 31.

[0022] The focusing lens 24 concentrates the light emitted from the light source unit 23 to a predetermined position at a predetermined distance from the light guide panel 25. The focusing lens 24 is, for example, a convex lens. The light concentrated at the predetermined position diffuses again and enters the incident surface 43 of the light guide panel 25.

[0023] The light guide panel 25 guides the light emitted from the light source unit 23 to the display panel 31. The light guide panel 25 is positioned opposite the multiple light source elements 41 in the second direction (X-axis direction). The light guide panel 25 is made of, for example, resin and is positioned close to the multiple light source elements 41 with a gap that does not cause deformation due to the heat of the multiple light source elements 41. The light guide panel 25 is composed of multiple transparent plates that guide the light. The light guide panel 25 has an incident surface 43, an exit surface 45, a bottom surface 47, and an opposing surface 49. The incident surface 43 and the opposing surface 49 are opposite surfaces, and the exit surface 45 and the bottom surface 47 are opposite surfaces. The incident surface 43 and the opposing surface 49 are the sides of the display panel 31 and intersect with the exit surface 45 and the bottom surface 47, respectively. In this embodiment, the first direction is also the direction perpendicular to the light guidance direction and the exit direction of the light on the incident surface 43.

[0024] The incident surface 43 is the surface to which light from the light source element 41 is incident. The incident surface 43 has a rectangular shape when viewed from the direction in which the light is incident. The longitudinal direction of the incident surface 43 is the first direction (Y-axis direction). The incident surface 43 is one end face of the light guide panel 25 in the second direction (X-axis direction) which is perpendicular to the third direction (Z-axis direction) in which the display panel 31 and the light guide panel 25 are stacked.

[0025] The opposing surface 49 faces the incident surface 43. The exit surface 45 is positioned in a direction intersecting the incident surface 43 and the opposing surface 49. Light incident from the incident surface 43 exits from the exit surface 45. The exit surface 45 is a surface defined by a first direction and a second direction perpendicular to the first direction. The exit surface 45 faces the display panel 31.

[0026] The bottom surface 47 faces the exit surface 45. The bottom surface 47 is inclined with respect to the exit surface 45. The distance between the bottom surface 47 and the exit surface 45 narrows as it moves away from the incident surface 43. As the distance between the bottom surface 47 and the exit surface 45 gradually narrows in the third direction (Z-axis direction), the shape of the cross section (XZ cross section) of the light guide panel 25, defined by the second and third directions, is wedge-shaped. The bottom surface 47 has a prism surface 51 formed on it, as shown in Figure 2(b). Figure 2(b) is a magnified view of a portion of the cross section of the bottom surface 47 of the light guide panel 25. A magnified view of a portion Ea of the bottom surface 47 shown in Figure 2(a) is shown in Figure 2(b).

[0027] The prism surface 51 has multiple prisms 51a. The prisms 51a have, for example, a wedge shape. The prisms 51a have a sloped surface 51c that is inclined toward the emission surface 45 from the surface 51b of the prism surface 51. The angle α between the sloped surface 51c and the surface 51b is preferably 5° or less. The prisms 51a increase the reflection angle of the light rays reflected by the bottom surface 47. As a result, the light rays reflected by the bottom surface 47 are more likely to deviate from the total internal reflection condition at the emission surface 45, and the amount of light emitted from the emission surface 45 can be increased.

[0028] The specular reflective member 27 is positioned along the light guide panel 25 at least on the side opposite the exit surface 45, i.e., on the bottom surface 47 side. The specular reflective member 27 reflects the light again inward from the light guide panel 25 when the light incident on the light guide panel 25 from the incident surface 43 is about to exit from the bottom surface 47. It is desirable that the material of the specular reflective member 27 has the highest possible reflectivity. The material of the specular reflective member 27 is, for example, metal. The specular reflective member 27 is formed, for example, by attaching a metal sheet to the bottom surface 47 of the light guide panel 25.

[0029] The light guide panel 25 has a rectangular shape with a long side and a short side, and in a plan view, multiple light source elements 41 are arranged in a line along the direction of the short side of the light guide panel 45.

[0030] The light ray direction changing member 29 is positioned on the exit side of the light guide panel 25. That is, the light ray direction changing member 29 is positioned between the light guide panel 25 and the display panel 31. The light ray direction changing member 29 changes the direction of travel of the entire light emitted from the light guide panel 25 to the direction in which the display panel 31 is located. The light ray direction changing member 29 has a row of triangular prisms on the surface of the light guide panel 25 facing the exit surface 45. The shape of these triangular prisms is a triangular prism shape with an axis parallel to the first direction as the matrix axis. These triangular prisms are arranged in the second direction. The apex angle of the triangular prisms is preferably about 60 degrees. The light ray direction changing member 29 deflects the light raised in the third direction by the triangular prisms so that it is perpendicular to the exit surface, thereby improving the front brightness.

[0031] The alignment lens 30 aligns the direction of light propagation from the light ray direction changing member 29 with respect to the display panel 31. The alignment lens 30 has different orientation directions in its central and peripheral parts. The alignment lens 30 is, for example, a concave Fresnel lens. The alignment lens 30 aligns the direction of light incident on the display panel 31 with that of the reflective optical unit 13.

[0032] The light rays emitted from the light guide panel 25 to the light ray direction changing member 29 rise in a third direction. Since the light rays are emitted from the emission surface 45 of the light guide panel 25 at an angle where the total internal reflection condition is broken, the angle of these emitted light rays is 60 to 70 degrees with respect to the third direction. By setting the apex angle of the triangular prism to approximately 60 degrees, the brightness can be maximized when the image display device 21 is viewed from the third direction.

[0033] The transmissive display panel 31 is positioned on the output side of the light ray direction changing member 29. The transmissive display panel 31 is, for example, a dot matrix display type Thin Film Transistor (TFT) transmissive liquid crystal panel. The image emitted from the display panel 31 may be either a still image or a moving image. The image may, for example, indicate the direction of travel of vehicle 1 or the status of vehicle 1.

[0034] The light guide panel 25 and the light ray direction changing member 29 are made of transparent materials having a predetermined refractive index. The refractive index of the transparent material is, for example, about 1.4 to 1.6. Examples of such transparent materials include epoxy resin, silicone resin, acrylic resin, and polycarbonate. In this embodiment, for example, polycarbonate is used considering its heat resistance.

[0035] Furthermore, in this embodiment, the video display device 21 is used in a head-up display 11 in which the range of the eye box Db is relatively limited. In other words, the light emitted by the video display device 21 has relatively high directivity. Therefore, the material of the light guide panel 25 is made of a material that is substantially free of scattering material. As a result, within the light guide panel 25, directional light rays are guided while repeatedly reflecting.

[0036] [1-2-3. Positional configuration of the light guide panel and the light source] The configuration of the incident surface 43 between the light guide panel 25 and the light source unit 23 of Embodiment 1 will be described in detail below with reference to Figures 4A and 4B. Figure 4A is a partially enlarged cross-sectional view of the vicinity of the light source unit 23 in Embodiment 1. Figure 4B is a cross-sectional view showing the configuration of the light source unit in Embodiment 1, where Figure 4B(a) is a cross-sectional view of the vicinity of the light source element 41 in Embodiment 1, and Figure 4B(b) is an enlarged view of the vicinity of the light focusing position P1. The cross-sections shown in Figures 4A and 4B are planes defined by a first direction and a second direction, i.e., XY cross-sections.

[0037] The light source element 41 includes a light-emitting element 41a that emits light and a collimating lens 41b that collimates the light emitted from the light-emitting element 41a. The light-emitting element 41a is a light-emitting element with a smaller light-emitting surface than a chip-type light-emitting diode (LED), and is, for example, a laser light-emitting element.

[0038] Light emitted from the light-emitting element 41a is collimated by the collimating lens 41b and emitted from the light source element 41. The width W1 of this collimated light is the width in the long axis direction (Y axis direction) of the pupil diameter, as shown in Figure 5A.

[0039] Light emitted from the light-emitting element 41a is focused to the focusing position P1 by the focusing lens 24, and then expanded again. When a laser light-emitting element is used as the light-emitting element 41a, the width of the light emitted from the light source unit 23 refers to the width W1a along the long axis of the pupil diameter of the light at the focusing position P1. The smaller the size of the light-emitting surface of the light-emitting element 41a, the smaller the width W1a of the light at the focusing position P1. The width W1a of the light at the focusing position P1 is less than 1 mm, for example, 0.5 mm or less. Note that when the light source unit 23 does not have a focusing lens 24, the width W1a of the light is the width W1 of the light emitted from the light source element 41.

[0040] Refer to Figure 4A. The incident surface 43 of the light guide panel 25 has a plurality of convex collimating lens portions 65, each facing one of the light source elements 41. The convex surface 65a of each collimating lens portion 65 is a curved surface that curves and protrudes in the direction facing each light source element 41. The axis of the center of curvature of each convex surface 65a is perpendicular to the XY plane. In other words, the axis of the center of curvature of each convex surface 65a is parallel to the third direction (Z-axis direction). The shape of each collimating lens portion 65 is, for example, cylindrical, a semi-cylindrical shape with a straight line parallel to the third direction as its matrix axis. The third direction is a direction perpendicular to both the first direction and the second direction. The plurality of collimating lens portions 65 are arranged in the first direction. Each collimating lens portion 65 is formed integrally with the light guide panel 25. The multiple collimating lens sections 65 are arranged to correspond to the light emitted from each of the multiple light source elements 41.

[0041] The condensing position P1 of the transmitted light of the condensing lens 24 coincides with the focal position F1 of the collimating lens unit 65. Here, the coincidence of the condensing position P1 and the focal position F1 includes not only the case of complete coincidence but also the case where the condensing position P1 and the focal position F1 are located in the vicinity of each other. For example, if the amount of displacement between the condensing position P1 and the focal position F1 is Lpf, the condensing position P1 and the focal position F1 may be in the vicinity as long as the amount of displacement Lpf satisfies the following relational expression using the focal length f of the collimating lens unit 65. -f / 5 < Lpf < f / 5 ··· Equation (1)

[0042] The pitch d between adjacent light source elements 41, the distance L from the focal position F1 of the condensing lens 24 to the main surface 65b of the collimating lens unit 65 of the light guide panel 25, and the maximum divergence angle θ of the light from the focal position F1 satisfy the following relational expression. The main surface 65b of the collimating lens unit 65 is a surface connecting the intersection 65c of the light that spreads from the light source unit 23 at the maximum divergence angle θ and the collimating lens unit 65. Also, the maximum divergence angle θ of the light is the divergence angle with respect to the optical axis. 1.6·L·tanθ ≦ d ≦ 2.0·L·tanθ ··· Equation (2) When this relationship is satisfied, the display panel can be illuminated uniformly.

[0043] The maximum divergence angle θ at which the light emitted from the light source unit 23 intersects the main surface 65b of the collimating lens unit 65 is 15 degrees or more and 60 degrees or less. The width W1a of the light emitted from the light source unit 23 is smaller than 1 / 3 of the width W2 of the main surface 65b of the collimating lens unit 65. By reducing the width W1a of the light emitted from the light source unit 23 so as to satisfy such a relationship, the light emitted from the light source unit 23 can be efficiently collimated by the collimating lens unit 65. <​More specifically, if the maximum divergence angle θ at which the light emitted from the light source 23 intersects the main surface 65b of the collimating lens 65 is 15 degrees or more and less than 30 degrees, the width W1a of the light emitted from the light source 23 may be less than 1 / 3 of the width W2 of the main surface 65b of the collimating lens 65. Also, if the maximum divergence angle θ is 30 degrees or more and less than 45 degrees, the width W1a of the light may be less than 1 / 4 of the width W2 of the main surface 65b. Furthermore, if the maximum divergence angle θ is 45 degrees or more and less than 50 degrees, the width W1a of the light may be less than 1 / 5 of the width W2 of the main surface 65b. Furthermore, if the maximum divergence angle θ is 50 degrees or more and less than 55 degrees, the width W1a of the light may be less than 1 / 6 of the width W2 of the main surface 65b. When the maximum angle of spread θ is between 55 and 60 degrees, the width of the light W1a may be less than 1 / 7 of the width W2 of the main surface 65b. For example, the width of the light W1a, the width W2 of the main surface 65b, and the maximum angle of spread θ satisfy the following relationship. W1a < W2 / tanθ / 4 ··· (3) formula When this relationship is satisfied, the light emitted from the light source unit 23 can be collimated more efficiently by the collimating lens unit 65.

[0045] Next, the pupil diameter of the laser light emitted from the light source element 41 will be explained with reference to Figures 5A and 5B. Figure 5A is a cross-sectional view taken along the VV arrow in Figure 4B(a), showing the pupil diameter of the light emitted from the light source element 41. Figure 5B is an explanatory diagram showing the eye box Db.

[0046] When a semiconductor laser is used as the light-emitting element 41a, for example, the laser light emitted from the light-emitting element 41a has different pupil diameters in the Y-axis direction and the Z-axis direction. For example, the pupil diameter 41aa of the laser light immediately after irradiation from the light source element 41 has an ellipse shape that extends in the Y-axis direction, and has a major axis in the Y-axis direction and a minor axis in the Z-axis direction. In the laser light, the divergence angle of the light in the major axis direction of the pupil diameter 41aa is smaller than that in the minor axis direction. As shown in Figure 5B, the eye box Db has a shape in which the horizontal length is longer than the vertical length. Therefore, in the eye box Db, the horizontal direction is the long side direction and the vertical direction is the short side direction. Thus, the light source element 41 is positioned so that the major axis direction of the pupil diameter 41aa, which has a smaller divergence angle, is in the short side direction (vertical direction) of the eye box, and the minor axis direction of the pupil diameter 41aa is in the long side direction (horizontal direction) of the eye box. This suppresses the spread of light in the short-side direction (vertical direction) of the eye box Db, reduces light escaping from the eye box Db, and improves the illuminance of the eye box Db. In addition, having a short axis in the Z-axis direction allows for more uniform illumination of the display panel.

[0047] [1-3. Effects, etc.] The effects of the head-up display 11 of this embodiment will be explained with reference to Figures 6 to 8. Figure 6 is a diagram showing the illumination distribution in the eye box Db by the head-up display 11 equipped with the video display device 21 of this embodiment. Figure 7 is a partially enlarged view of the vicinity of the light source element 42 in the comparative example. Figure 8 is a diagram showing the illumination distribution in the eye box Db by the head-up display equipped with the video display device of the comparative example.

[0048] As shown in Figure 7, the light source element 42 of the comparative example's light source unit 26 has, for example, an LED and has a large light-emitting surface. As a result, the light emitted from the light source element 42 cannot be completely collimated by the collimating lens portion 65 of the light guide panel 25, and the light propagates while spreading out. Consequently, as shown in Figure 8, the amount of light spreading outside the eye box Db increases, and the illuminance inside the eye box Db decreases. In Figure 8, region Sa1 is the region with an illuminance of 3.7 or more and less than 7.4, region Sa2 is the region with an illuminance of 7.4 or more and less than 11.1, region Sa3 is the region with an illuminance of 11.1 or more and less than 14.8, and region Sa4 is the region with an illuminance of 14.8 or more.

[0049] In contrast, the video display device 21 of this embodiment comprises a light source unit 23 having a light source element 41 that emits light, a condensing lens 24 that focuses the light emitted from the light source unit 23, a display panel 31 that displays an image, and a light guide panel 25 that guides the light from the condensing lens 24 to the display panel. The light source element 41 has a smaller light-emitting surface than a light-emitting diode.

[0050] As a result, a small amount of light from the light source unit 23 is incident on the light guide panel 25, which suppresses the spread of light and increases the amount of light propagating within the eye box Db. Therefore, an image display device 21 with increased light intensity can be provided.

[0051] As shown in Figure 6, the illuminance inside the eye box Db can be improved compared to the comparative example. In this embodiment, the illuminance distribution of the eye box Db shows areas Sa5 to Sa11 with higher illuminance than areas Sa1 to Sa4 in the comparative example's illuminance distribution. Area Sa5 is an area with an illuminance of 18.5 or higher, area Sa8 is an area with an illuminance of 29.6 or higher, and area Sa10 is an area with an illuminance of 40.7 or higher.

[0052] In particular, when light from the light source element 41 is incident from the short side direction of the light-emitting surface 45 of the light guide panel 25, it is difficult to suppress the vertical spread of light in the eye box Db even with the light ray direction changing member 29 and the collimating lens portion 65 of the light guide panel 25. In contrast, by using a light source element 41 with a smaller light-emitting surface than a light-emitting diode, the vertical spread of light in the eye box Db can be suppressed, and the illuminance inside the eye box Db can be improved.

[0053] Furthermore, in the eye box Db, light must be diffused in the horizontal direction (long side), but if the light is also diffused in the vertical direction (short side) to match the direction of the long side, the brightness in the short side will decrease. Therefore, it is desirable that the beam angle in the short side direction of the eye box Db is smaller than the beam angle in the long side direction of the eye box Db. When a laser element is used as the light source element 41, the divergence angle of light in the long axis direction of the pupil diameter of the laser beam is smaller than the divergence angle of light in the short axis direction. Therefore, by arranging the laser element so that the long axis direction of the pupil diameter of the laser beam emitted from the light source element 41 corresponds to the short side direction of the eye box Db, the spread of light in the short side direction can be suppressed more than in the long side direction of the eye box Db.

[0054] Furthermore, in this embodiment, the head-up display 11 includes an image display device 21. This makes it possible to provide a head-up display 11 with increased light intensity.

[0055] Furthermore, in this embodiment, the vehicle 1, as a mobile body, is equipped with a head-up display 11. This makes it possible to provide a vehicle 1 equipped with a head-up display 11 with increased light intensity.

[0056] Next, a modified example of the light guide panel 25 of this embodiment will be described with reference to Figure 9. Figure 9 is a partially enlarged cross-sectional view of the vicinity of the light source element 41 in a modified example of Embodiment 1. As shown in Figure 9, the incident surface 43A has protrusions 67 that are in contact with the outer circumferential surface of each collimating lens portion 65 and extend toward the light source element 41. Since the protrusions 67 are formed between adjacent collimating lens portions 65, light spreading in the width direction can be collimated. Alternatively, the protrusions 67 may be formed on the upper and lower parts of the collimating lens portion 65, in which case light spreading in the vertical direction can be collimated.

[0057] The protruding portion 67 allows for greater collimation of the light rays emitted from the light source element 41, thereby focusing more light rays into the light guide panel 25.

[0058] (Embodiment 2) The image display device 21B of Embodiment 2 will be described below with reference to Figures 10 and 11. Figure 10 is a schematic cross-sectional view of the image display device in Embodiment 2. Figure 11 is a partially enlarged cross-sectional view of the light source element and light guide panel in Embodiment 2. In the image display device 21B of Embodiment 2, an optical fiber is arranged between the condensing lens 24 and the light guide panel 25. In Embodiment 2, components having the same configuration and function as those in Embodiment 1 are denoted by the same reference numerals, and detailed descriptions and similar effects may be omitted.

[0059] [2-1. Structure] The image display device 21B comprises a light source unit 23B, a focusing lens 24, a display panel 31, a light guide panel 25, and an optical fiber 71. The optical fiber 71 is positioned between the focusing lens 24 and the light guide panel 25, and light from the focusing lens 24 is propagated to the light guide panel via the optical fiber 71. For example, the aperture 71a of the optical fiber 71 on the light source unit 23B side is positioned at the focusing position P1 of the focusing lens 24, and the output port 71b of the optical fiber 71 on the display panel 31 side is positioned at the focal position F1 of the collimating lens unit 65 on the incident surface 43 of the display panel 31. The light source element 41 may have, for example, red, green, and blue laser elements. This allows three colors of laser light to be emitted from each light source element 41.

[0060] The optical fiber 71 allows the light source unit 23B to be placed outside the housing 15, thereby increasing the flexibility in the placement of the video display device 21B in the vehicle 1. Furthermore, when the light source unit 23B is placed outside the housing 15, the heat sink 73 for dissipating heat from the light source element 41 can also be placed outside the housing 15, so the video display device 21B can be equipped with a heat sink 73 of sufficient size to dissipate heat from the light source element 41.

[0061] The optical fiber 71 is arranged in a first direction corresponding to the pair of light source elements 41 and the condensing lens 24 between the pair of light source elements 41 and the condensing lens 24 and the collimating lens section 65.

[0062] [2-2. Effects, etc.] As described above, the video display device 21B of this embodiment includes an optical fiber 71 positioned between the condensing lens 24 and the light guide panel 25, and light from the condensing lens 24 is propagated to the light guide panel 25 via the optical fiber 71.

[0063] This allows for an increase in the amount of light incident on the eye box Db. Furthermore, it is possible to provide a video display device 21 with increased light intensity and a head-up display 11 equipped with the video display device 21. Additionally, the light source unit 23 and the light guide panel 25 can be sufficiently separated, reducing the transfer of heat from the light source unit 23 to the light guide panel 25.

[0064] Furthermore, the light source unit 23 is equipped with a heat sink 73 to dissipate heat from the light source element 41. This allows the use of a higher-power light source unit 23, further improving the illuminance inside the eye box Db.

[0065] Next, with reference to Figure 12, a modified example 1 of the video display device of Embodiment 2 will be described. Figure 12 is a partially enlarged cross-sectional view of the video display device in a modified example of Embodiment 2. As shown in Figure 12, in the video display device 21C, the pitch d2 between the exit ports 71b of the optical fiber 71, that is, the pitch d2 between the multiple collimating lens portions 65 of the light guide panel 25, is smaller than the pitch Pt1 between the multiple light source elements 41. By using optical fiber 71, the pitch of the light emitted from each light source element 41 can be shortened, so it is possible to accommodate a miniaturized video display device 21 and light guide panel 25, and the density of light from the light source unit 23B can be increased.

[0066] Next, a modification 2 of the image display device of Embodiment 2 will be described with reference to Figure 13. Figure 13 is a partially enlarged cross-sectional view of the image display device 21D in modification 2 of Embodiment 2. As shown in Figure 13, in the image display device 21D, a phosphor 75 is placed between the optical fiber 71 of the image display device 21B of Embodiment 2 and the collimating lens portion 65 of the light guide panel 25. The light source element 41D of the light source unit 23D is a laser light that emits blue light, and the emitted blue light irradiates the phosphor 75 via the optical fiber 71, causing yellow fluorescence to enter the light guide panel 25 together with the blue light that passes through the phosphor 75. As a result, white light is irradiated onto the light guide panel 25. Since only blue light can be used in the light source element 41D, high-power light can be emitted, and the illuminance inside the eye box Db can be further improved.

[0067] Next, with reference to Figure 14, a third modification of the video display device of Embodiment 2 will be described. Figure 14 is a partially enlarged cross-sectional view of the video display device 21E in the third modification of Embodiment 2. As shown in Figure 21E, the optical fiber 71A of the video display device 21E comprises a light source side optical fiber 71Aa, a branch coupler 71Ac, and an output side optical fiber 71Ab. The optical fiber 71A branches from a single light source side optical fiber 71Aa on the light source element 41E side to a plurality of output side optical fibers 71Ab on the light guide panel side. The light source side optical fiber 71Aa is branched to a plurality of output side optical fibers 71Ab via, for example, a branch coupler 71Ac.

[0068] Light emitted from the light source element 41E enters the light source-side optical fiber 71Aa via the focusing lens 24, is branched by the branching coupler 71Ac, and propagates to each output-side optical fiber 71Ab. Light emitted from each output port 71b of each output-side optical fiber 71Ab enters the light guide panel 25. In this way, by using optical fibers 71A with branched output sides, the number of light source elements 41E can be reduced, and the light source unit 23E can be miniaturized.

[0069] Next, with reference to Figure 15, a modified example 4 of the video display device of Embodiment 2 will be described. Figure 15 is a partially enlarged cross-sectional view of the video display device 21F in modified example 4 of Embodiment 2. As shown in Figure 15, the video display device 21F further includes a half mirror 77 that splits the light from the light source element 41F of the light source unit 23F, and a mirror 79 that totally reflects the light from the light source element 41F.

[0070] The half mirrors 77 are positioned in the optical path between the light source element 41F and the condensing lens 24, corresponding to the optical fibers 71 and condensing lenses 24 positioned opposite each collimating lens section 65. The mirror 79 is positioned to face the furthest condensing lens 24 into which the light from the light source element 41F is incident. The reflectivity of each half mirror 77 is designed to increase sequentially from the half mirror closest to the light source element 41F, so that the amount of reflected light from each half mirror 77 and mirror 79 is the same.

[0071] Light emitted from the light source element 41F is split by the half mirror 77 and incident on the optical fiber 71 via the focusing lens 24. The light, which has been split multiple times by the half mirror 77, is totally reflected by the mirror 79 and incident on the optical fiber 71. In this way, by using the half mirror 77 and the mirror 79, the number of light source elements 41F can be reduced, and the light source unit 23F can be miniaturized.

[0072] As described above, Embodiments 1 and 2 and their modifications have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that are modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to create new embodiments by combining the components described in Embodiments 1 and 2 and their modifications. Therefore, other embodiments are described below as examples.

[0073] In the above embodiment, a TFT transmissive liquid crystal panel was used as an example of a transmissive display panel 31, but other display elements can be used as long as they are transmissive display devices.

[0074] In the above embodiment, the light guide panel 25 and the display panel 31 are arranged parallel to each other, but they can also be arranged at an angle.

[0075] The mobile device on which the head-up display 11 of this embodiment is mounted is not limited to automobiles or other vehicles, but also includes railway cars, motorcycles, aircraft, helicopters, ships, and various other devices that transport people.

[0076] As described above, embodiments have been explained as examples of the technology in this disclosure. For this purpose, accompanying drawings and a detailed description have been provided.

[0077] Therefore, the components described in the attached drawings and detailed descriptions may include not only components essential for solving the problem, but also components that are not essential for solving the problem, provided that they illustrate the technology described above. For this reason, the mere presence of these non-essential components in the attached drawings and detailed descriptions should not be immediately assumed to mean that they are essential.

[0078] Furthermore, since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents.

[0079] (Summary of the embodiment) (1) The video display device of this disclosure comprises a light source unit having a light source element that emits light, a display panel that displays an image, and a light guide panel that guides light from the light source unit to the display panel. The light guide panel has a collimating lens unit that collimates the light from the light source unit to the incident surface into which the light from the light source unit is incident. The maximum divergence angle θ at which the light emitted from the light source unit intersects the main surface of the collimating lens unit is 15 degrees or more and 60 degrees or less, and the width of the light emitted from the light source unit is less than 1 / 3 of the width of the main surface of the collimating lens unit.

[0080] As a result, a small amount of light from the light source is incident on the light guide panel, which suppresses the spread of light and increases the amount of light propagating within the eye box.

[0081] (2) In the video display device of (1), the light source unit has a plurality of light source elements. The light guide panel has an incident surface facing the light source unit, an exit surface facing the display panel, and a bottom surface on the opposite side of the display panel that faces the exit surface. The incident surface is the side surface of the light guide panel located between the exit surface and the bottom surface. The exit surface has a rectangular shape composed of a long side and a short side, and in a plan view, a plurality of light source elements are arranged along the direction of the short side of the exit surface.

[0082] (3) In the video display device of (1) or (2), the light source unit is equipped with a focusing lens that focuses the light emitted from the light source element.

[0083] In the video display device of (4)(3), the positional difference Lpf between the light collection position of the light-transmitted light of the condensing lens and the focal position of the collimating lens, and the focal length f of the collimating lens satisfy the following relationship. -f / 5 <Lpf <f / 5

[0084] (5) In any one of the video display devices described in (1) to (4), the light source element has a laser element.

[0085] (6) In any one of the video display devices described in (1) to (5), the width of the light emitted from the light source is 0.5 mm or less.

[0086] In the image display device of (7)(5), the laser elements are arranged such that the direction of the major axis of the pupil diameter of the light emitted from the laser elements corresponds to the direction of the short side of the eye box, which is the viewing area of ​​the image.

[0087] (8) An image display device according to any one of (1) to (7), comprising: a light ray direction changing member that changes the direction of propagation of the entire light emitted from the light guide panel to the direction in which the display panel is located; and a light distribution lens that changes the direction of propagation of the light from the light ray direction changing member between the central part and the peripheral part with respect to the display panel.

[0088] In the video display device of (9)(4), the pitch d between light source elements, the distance L from the focal position of the focusing lens to the collimating lens of the light guide panel, and the spread of light θ from the focal position satisfy the following relationship: 1.6·L·tanθ≦d≦2.0·L·tanθ

[0089] In the image display device of (10)(4) or (9), there is a projection that is in contact with the outer circumferential surface of the collimating lens portion and extends toward the light source portion.

[0090] (11) An image display device according to any one of (1) to (10) is provided with an optical fiber placed between a light source and a light guide panel, wherein light from the light source is transmitted to the light guide panel via the optical fiber.

[0091] In the video display device of (12)(11), the light source is located away from the light guide panel via an optical fiber, and the light source located away from the light guide panel is equipped with a heat sink for dissipating heat from the light source element.

[0092] (13) In the video display device of (11) or (12), the pitch between the exit ports of the optical fibers is smaller than the pitch between the multiple light source elements.

[0093] (14) In the video display device of (11) or (12), a phosphor is placed between the optical fiber and the light guide panel, blue light is emitted from the light source element, the blue light from the light source element irradiates the phosphor, and white light is incident on the light guide panel.

[0094] In the video display device of (15)(11) or (12), the optical fiber is branched from one fiber on the light source element side to multiple fibers on the light guide panel side.

[0095] In the image display device of (16)(3), an optical fiber is placed between the light source and the light guide panel, and a half mirror is placed in the optical path between the light source element and the focusing lens, wherein light from the light source propagates to the light guide panel via the optical fiber, the light from the light source element is split by the half mirror, and the split light enters the optical fiber.

[0096] (17) A head-up display equipped with one of the image display devices described in (1) through (16).

[0097] A mobile device equipped with a head-up display, as described in (18)(17). [Industrial applicability]

[0098] This disclosure is applicable to video display devices. Furthermore, this disclosure is applicable to head-up displays equipped with video display devices. [Explanation of Symbols]

[0099] 1 vehicle 3 Windshield 11. Head-Up Display 13 Reflective Optical Unit 15 cabinets 17 First Mirror 19. Second Mirror 21 Video display device 23, 26 Light source section 24 Focusing lenses 25 Light guide panel 27 Mirror-like reflective member 29. Ray direction changing member 30 oriented lenses 31 Display Panel 41 Light source elements 41a Light-emitting element 41b Collimating Lens 41aa pupil diameter 42 light source elements 43 Incidence plane 45 Ejection surface 47 Bottom 49 Opposite side 51 Prism surface 51a Prism 51b Sheet surface 51c Slope 65 Collimating lens section 67 Protrusion 71, 71A Optical Fiber 71a aperture 71b Output port 71Aa Light source side optical fiber 71Ab Outgoing optical fiber 71Ac Branch Coupler 73 Heatsink 75 Phosphors 77 Half Mirror 79 Miller Da Observer Db ibox F1 focal position P1 Light-gathering position

Claims

1. A light source unit having a light source element that emits light, A display panel that displays images, The system includes a light guide that guides light from the light source to the display panel, The light guide has a lens portion on the incident surface into which light from the light source unit is incident, which protrudes in a first direction opposite to the light source unit and has a curved surface shape that moves away from the light source unit in a second direction perpendicular to the first direction. The maximum divergence angle θ at which the light emitted from the light source intersects the main surface of the lens is between 15 degrees and 60 degrees. The minimum width of the light emitted immediately after being emitted from the light source element of the light source unit is less than 1 / 3 of the width of the main surface of the lens unit. Video display device.

2. The light source unit has a plurality of light source elements, The light guide has an incident surface facing the light source, an exit surface facing the display panel, and a bottom surface on the opposite side of the display panel that faces the exit surface. The incident surface is the side surface of the light guide located between the exit surface and the bottom surface. The aforementioned emission surface has a rectangular shape composed of a long side and a short side. In a plan view, the plurality of light source elements are arranged along the short-side direction of the emission surface. The video display device according to claim 1.

3. The light source unit includes a focusing lens that focuses the light emitted from the light source element. The video display device according to claim 1 or 2.

4. The positional displacement Lpf between the light-collecting position of the light-transmitted light of the condensing lens and the focal position of the lens portion, and the focal length f of the lens portion satisfy the following relationship: The video display device according to claim 3. -f / 5 <Lpf <f / 5

5. The aforementioned light source element has a laser element. The video display device according to any one of claims 1 to 4.

6. The light source element has a collimating lens element that collimates the light emitted from the laser element before irradiating it. The minimum width of the light emitted immediately after being emitted from the light source element of the light source unit is 0.5 mm or less. The video display device according to claim 5.

7. The laser elements are positioned such that the direction of the major axis of the pupil diameter of the light emitted from the laser elements corresponds to the direction of the short side of the eye box, which is the viewing area of ​​the image. The video display device according to claim 5.

8. A light ray direction changing member that changes the direction of propagation of the entire light emitted from the light guide to the direction of the display panel, The system includes an orientation lens that changes the direction of light propagation from the light ray direction changing member between the central and peripheral parts of the display panel. The video display device according to any one of claims 1 to 7.

9. The pitch d between the light source elements, the distance L from the focal position of the condensing lens to the lens portion of the light guide, and the maximum divergence angle θ of the light from the focal position satisfy the following relationship: The video display device according to claim 4. 1.6・L・tanθ≦d≦2.0・L・tanθ

10. The lens portion has a protrusion that is in contact with the outer circumferential surface and extends toward the light source portion, The video display device according to claim 4 or 9.

11. The light source unit and the light guide are provided with an optical fiber positioned between them. Light from the light source is transmitted to the light guide via the optical fiber. The video display device according to any one of claims 1 to 8.

12. The light source unit is positioned away from the light guide via the optical fiber, The light source unit, which is positioned away from the light guide, is equipped with a heat sink for dissipating heat from the light source element. The video display device according to claim 11.

13. The pitch between the exit ports of the optical fiber is smaller than the pitch between the multiple light source elements. The video display device according to claim 11 or 12.

14. The optical fiber and the light guide are provided with a phosphor positioned between them. Blue light is emitted from the aforementioned light source element, Blue light from the light source element irradiates the phosphor, and white light is incident on the light guide. The video display device according to claim 11 or 12.

15. The optical fiber is branched from one fiber on the light source element side to multiple fibers on the light guide side. The video display device according to claim 11 or 12.

16. An optical fiber is disposed between the light source and the light guide, A half-mirror is provided in the optical path between the light source element and the focusing lens, Light from the light source is transmitted to the light guide via the optical fiber. The light from the light source element is split by the half-mirror. The divided light is incident on the optical fiber. The video display device according to claim 3.

17. A video display device according to any one of claims 1 to 16, Head-up display.

18. A head-up display as described in claim 17, A mobile object.

Images