Lens and Head-up Display Device

Abstract

To provide a lens that can be reduced in thickness while maintaining the diffusion angle of light, and a head-up display device.SOLUTION: A third lens 53 diffusing light from a light source toward a liquid crystal display panel comprises: a toroidal area 54T having a toroidal surface that is along a surface direction of the third lens 53 and is curved in both an X-direction and a Y-direction intersecting each other; and Fresnel areas 54L, 54R that are formed on both sides in the X-direction of the toroidal area 54T and have a Fresnel lens shape.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a lens and a head-up display device.

Background Art

[0002] For example, the display device described in Patent Document 1 includes a light source, first to third lenses through which light from the light source passes, a liquid crystal display panel that receives the light that has passed through the first to third lenses and emits display light, and a concave mirror that displays a virtual image by reflecting the display light from the liquid crystal display panel toward a projection member such as a front glass. The third lens has a toroidal surface capable of diffusing light in accordance with the liquid crystal display panel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the third lens described in Patent Document 1 has a toroidal surface over the entire light incident surface, it is thick. In particular, when the diffusion angle of the third lens is increased in accordance with the size of the liquid crystal display panel, it is necessary to increase the curvature of the toroidal surface, and the third lens tends to be thick. For this reason, thinning of the third lens has been demanded.

[0005] The present disclosure has been made in view of the above situation, and an object thereof is to provide a lens and a head-up display device capable of achieving thinning while maintaining the light diffusion angle.

Means for Solving the Problems

[0006] To achieve the above object, a lens according to a first aspect of the present disclosure is a lens that diffuses light from a light source toward a display panel, and has a toroidal region having a toroidal surface that curves in a first direction and a second direction that intersect each other along the surface direction of the lens, a Fresnel region formed on both sides of the toroidal region in the first direction and having a Fresnel lens shape, and a plurality of cylindrical lens portions formed on the back surface of the surface on which the toroidal region and the Fresnel region of the lens are formed, extending along the second direction, and arranged in the first direction. The curvature of the cylindrical lens portion corresponding to the toroidal region among the plurality of cylindrical lens portions is formed to be larger than the curvature of the cylindrical lens portion corresponding to the Fresnel region among the plurality of cylindrical lens portions. 。

[0007] To achieve the above object, a head-up display device according to a second aspect of the present disclosure includes the lens, the light source, and the display panel that receives the light from the light source transmitted through the lens and generates display light.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to achieve thinning while maintaining the light diffusion angle.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] An embodiment of a lens, a head-up display device, and a mold according to the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the head-up display device 100 is installed, for example, in the dashboard of the vehicle 200. The head-up display device 100 emits display light L representing an image toward the windshield 201 of the vehicle 200, and displays a virtual image V by the display light L reflected by the windshield 201.

[0011] As shown in FIG. 2, the head-up display device 100 includes a display unit 10, a concave mirror 20, a housing 30, and a heat dissipation member 40.

[0012] The housing 30 is formed in a box shape with a light-shielding resin or the like, and houses the display unit 10 and the concave mirror 20. An opening 30c is formed in the housing 30 at a position facing the windshield 201 (see FIG. 1) in the height direction. The housing 30 includes a window portion 31 formed in a curved plate shape made of a light-transmitting resin such as acrylic that is fitted into the opening 30c and through which the display light L passes.

[0013] The heat dissipation member 40 is a member that releases the heat generated by the display unit 10 to the outside. The heat dissipation member 40 is, for example, a fin-type structure formed of a metal such as aluminum. The heat dissipation member 40 is fitted into the fitting hole portion 32 of the housing 30 so that a part thereof is exposed outside the head-up display device 100.

[0014] The display unit 10 emits the display light L. The specific configuration of the display unit 10 will be described later. The concave mirror 20 reflects the display light L from the display unit 10 toward the windshield 201.

[0015] Next, the specific configuration of the display unit 10 will be described. As shown in FIG. 2, the display unit 10 includes a backlight unit 11 and a display panel unit 13. The backlight unit 11 is a device that illuminates the liquid crystal display panel 18. The backlight unit 11 includes first to third lenses 51 to 53, a plurality of light sources 19, a substrate 16, and a first case body 14. The substrate 16 and the first to third lenses 51 to 53 are arranged along the traveling direction of the light emitted by the light source 19. Hereinafter, this traveling direction of the light is defined as the Z direction, the longitudinal direction orthogonal to the Z direction in the substrate 16 and the first to third lenses 51 to 53 is defined as the X direction, and the short-side direction is defined as the Y direction.

[0016] Each light source 19 is composed of, for example, an LED (Light Emitting Diode). The plurality (12 in this example) of light sources 19 are provided on the surface of the substrate 16 facing the first lens 51. Specifically, when the Y direction is the row direction and the X direction is the column direction, the light sources 19 are arranged in a 2-row × 6-column matrix. The first case body 14 is formed in a rectangular cylindrical shape extending in the Z direction with a light-shielding resin or the like, and houses the substrate 16 and the first to third lenses 51 to 53.

[0017] As shown in FIG. 6, the first to third lenses 51 to 53 are arranged in the order of the first lens 51, the second lens 52, and the third lens 53 from the side closer to the light source 19. The light from the light source 19 passes through them in the thickness direction in the order of the first lens 51, the second lens 52, and the third lens 53.

[0018] As shown in FIGS. 3 and 4, the first lens 51 is formed of a transparent optical resin or optical glass. The first lens 51 parallelizes the light emitted from the light source 19 in the Z direction. The first lens 51 includes a plurality of convex lens portions 51a. The plurality of convex lens portions 51a are arranged in a 2-row × 6-column matrix in the same manner as the above-described light sources 19.

[0019] As shown in FIG. 3, the second lens 52 is formed of a transparent optical resin or optical glass and has a function of diffusing the light transmitted through the first lens 51 in the Y direction. The second lens 52 is, for example, a lenticular lens. Specifically, the second lens 52 includes an incident surface 52i on which light is incident and an emission surface 52o from which the light that has passed through the second lens 52 in its thickness direction is emitted.

[0020] On the incident surface 52i of the second lens 52, a plurality (11 in this example) of cylindrical lens portions 52a are formed. On the emission surface 52o of the second lens 52, a plurality (11 in this example) of cylindrical lens portions 52b are formed. Each of the cylindrical lens portions 52a, 52b is formed in a convex shape, for example, a semi-cylindrical shape, extends along the X direction, and is arranged in the Y direction.

[0021] As shown in FIG. 7, the third lens 53 is formed of a transparent optical resin or optical glass. The third lens 53 has an optical surface that exhibits optical characteristics symmetric with respect to the lens center point 53D through which the central ray of the light that has passed through the second lens 52 from the light source 19 passes. As shown in FIG. 4, the third lens 53 diffuses the light from the light source 19 that has passed through the second lens 52 in the X direction so as to be aligned with the liquid crystal display panel 18.

[0022] Specifically, as shown in FIG. 9, the third lens 53 includes a lens main body portion 54 and an outer frame portion 55. The outer frame portion 55 has a frame shape surrounding the outer periphery of the lens main body portion 54. The outer frame portion 55 is located at the same height as the incident surface 54i. The outer frame portion 55 includes convex plate portions 55c formed on both sides extending in the X direction. The convex plate portions 55c have a rectangular plate shape that is long in the X direction.

[0023] The outer frame portion 55 includes a plurality of pin through-hole portions 55b. The plurality of pin through-hole portions 55b have holes penetrating in the thickness direction of the outer frame portion 55. A positioning pin (not shown) is inserted into each pin through-hole portion 55b. This positioning pin is provided on the first case body 14 (see FIG. 2). In this example, a plurality of, specifically one pin through-hole portion 55b is provided on each convex plate portion 55c. Also, each pin through-hole portion 55b is located at the center in the X direction of the third lens 53.

[0024] As shown in FIG. 10, the outer frame portion 55 includes a plurality of spacers 55a. In this example, a plurality of, specifically four spacers 55a are formed on the back surface of the outer frame portion 55 and have a columnar shape extending along the Z direction. As shown in FIG. 6, the back surface of the outer frame portion 55 is a surface facing the second lens 52. The plurality of spacers 55a are positioned so as to sandwich the pin through-hole portion 55b in the X direction. The distance between the second lens 52 and the third lens 53 is defined by the tip surface of each spacer 55a coming into contact with the outer peripheral frame portion 52c of the second lens 52.

[0025] As shown in FIG. 8, the lens main body portion 54 includes an incident surface 54i on which light is incident, and an emission surface 54o which is an example of the above optical surface through which the light that has passed through the inside of the third lens 53 in its thickness direction is emitted. As shown in FIG. 7, the emission surface 54o includes a toroidal region 54T and Fresnel regions 54L, 54R. The toroidal region 54T has a toroidal surface formed with different curvatures in the X direction and the Y direction. For example, the toroidal region 54T is curved concave along the X direction and convex along the Y direction. In the toroidal region 54T, as it approaches the central portion in the X direction, it becomes a lower position in the Z direction (the thickness direction of the third lens 53). In the toroidal region 54T, as it approaches the central portion in the Y direction, it becomes a higher position in the Z direction. The lowest position P1 of the toroidal region 54T is the center of the toroidal region 54T in the X direction and the positions at both ends of the toroidal region 54T in the Y direction. The highest position P2 of the toroidal region 54T is the center of the toroidal region 54T in the Y direction and the positions at both ends of the toroidal region 54T in the X direction. The curvature of the toroidal region 54T in the X direction is formed to be larger than the curvature of the toroidal region 54T in the Y direction. As shown in FIG. 9, the toroidal region 54T is formed in a substantially rectangular shape that is long in the X direction. Specifically, both sides extending along the Y direction of this substantially rectangular shape are curved outward.

[0026] The Fresnel regions 54L and 54R are located on both sides of the lens main body 54 in the X direction and have a Fresnel lens shape. The Fresnel regions 54L and 54R are arranged so as to sandwich the toroidal region 54T. The Fresnel regions 54L and 54R each have a substantially square shape in which the sides in contact with the toroidal region 54T are curved in a concave shape. The Fresnel regions 54L and 54R are curved convexly in the Y direction and are highest at the center in the Y direction.

[0027] As shown in FIG. 11, the Fresnel regions 54L and 54R each include a plurality of ridges 54Y. The plurality of ridges 54Y are curved and extend along the Y direction and are arranged in the X direction. The cross-sectional shape of the ridge 54Y is triangular, and in this example, a right-angled triangular shape. The optical surface of the ridge 54Y includes a first side 541 inclined in the X direction and a second side 542 located outside the ridge 54Y in the X direction. The second side 542 extends along the Z direction.

[0028] As shown in FIG. 9, each ridge 54Y of the Fresnel region 54L extends along a concentric arc centered on the center point O1. Each ridge 54Y of the Fresnel region 54L is arranged at regular intervals K (see FIG. 11) in the radial direction centered on the center point O1. The regular interval K is the same length as the base of the ridge 54Y. The center point O1 is provided at a position closer to the Fresnel region 54R than the lens center point 53D, and in this example, is located within the Fresnel region 54R. Specifically, the center point O1 is located outside (the right side in FIG. 9) the center in the X direction within the Fresnel region 54R.

[0029] The crest portions 54Y of the Fresnel region 54R extend along concentric arcs centered on the center point O2. Each crest portion 54Y of the Fresnel region 54R is arranged at regular intervals K in the radial direction centered on the center point O2. The center point O2 is provided at a position closer to the Fresnel region 54L than the lens center point 53D, and in this example, it is located within the Fresnel region 54L. Specifically, the center point O2 is located outside (the left side in FIG. 9) the center in the X direction within the Fresnel region 54L. The lens center point 53D is positioned so as to be aligned with the center points O1 and O2 in the X direction.

[0030] As shown in FIG. 5, the incident surface 54i includes lenticular regions 54A, 54B, and 54C. Each lenticular region 54A, 54B, 54C includes a plurality of cylindrical lens portions 54S. The plurality of cylindrical lens portions 54S are each formed in a semi-cylindrical shape extending along the Y direction and are arranged in the X direction. The lenticular region 54A is formed in a region corresponding to the Fresnel region 54L on the front and back surfaces of the third lens 53. The lenticular region 54B is formed in a region corresponding to the Fresnel region 54R on the front and back surfaces of the third lens 53. The lenticular region 54C is formed in a region corresponding to the toroidal region 54T on the front and back surfaces of the third lens 53. The lenticular regions 54A, 54B are positioned so as to sandwich the lenticular region 54C in the X direction. The curvature of each cylindrical lens portion 54S of the lenticular region 54C is set to be larger than the curvature of each cylindrical lens portion 54S of the lenticular regions 54A, 54B. The pitch of the plurality of cylindrical lens portions 54S is set to be the same in each of the lenticular regions 54A, 54B, 54C. As shown in FIG. 9, the boundary line BL1 between the lenticular regions 54A, 54B and the lenticular region 54C passes through the central portion in the Y direction of the boundary line BL2 between the Fresnel regions 54L, 54R and the toroidal region 54T. Note that, not limited to this example, the boundary line BL1 may pass through the end portion in the Y direction of the boundary line BL2.

[0031] As shown in FIG. 2, the display panel unit 13 includes a liquid crystal display panel 18, a light diffusing member 17, and a second case body 15. The second case body 15 has a frame shape that holds the light diffusing member 17 and the liquid crystal display panel 18 from the outer periphery, and is fixed within the housing 30. The light diffusing member 17 is provided on the side facing the third lens 53 of the liquid crystal display panel 18. The light diffusing member 17 diffuses the light from the third lens 53 and emits it to the liquid crystal display panel 18.

[0032] The liquid crystal display panel 18 receives illumination light from the backlight unit 11 and emits display light L representing an image toward the concave mirror 20. The liquid crystal display panel 18 is a TFT (Thin Film Transistor) type liquid crystal panel. Thus, the description of the configuration of the head-up display device 100 is completed.

[0033] Next, the process leading to the configuration of the third lens 53 according to the present embodiment will be described. As shown in FIG. 12, the light emitting surface 153o of the third lens 153 according to the first comparative example has a toroidal surface shape throughout. For this reason, there was a problem that the third lens 153 according to the first comparative example became thick. In particular, recently, in head-up display devices, it has been required to make the display unit that emits display light compact while increasing the size of the virtual image or increasing the eyebox (the space where the virtual image can be visually recognized). Therefore, in order to increase the diffusion angle θ of the light transmitted through the third lens 153, it is necessary to increase the curvature of the light emitting surface 153o, and thus the problem that the third lens 153 becomes thick has become more prominent. In order to solve this problem, as shown in FIG. 13, by forming the outer side of the light emitting surface 253o of the third lens 253 according to the second comparative example with the Fresnel regions 54L and 54R, the third lens 253 was made thinner. In the configuration of the third lens 153 according to the first comparative example, the outermost light ray Lz in the X direction passes through the liquid crystal display panel 18. Therefore, as shown in FIG. 14, the variation in the luminance of the virtual image when the viewer views from the center of the eye box is small. On the other hand, in the configuration of the third lens 253 according to the second comparative example, as a result of the thinning, the light emitting surface 253o moves away from the liquid crystal display panel 18. Therefore, there is a possibility that the outermost light ray Lz passes through a range exceeding the liquid crystal display panel 18. For this reason, as shown in FIG. 15, the luminances of the outer ends E1 and E2 in the left-right direction of the virtual image when the viewer views from the center of the eye box become low, and the variation in the luminance of the virtual image becomes large. In order to solve this problem, in the present embodiment, as shown in FIG. 5, the curvature of each cylindrical lens portion 54S of the lenticular regions 54A and 54B is set to be smaller than the curvature of each cylindrical lens portion 54S of the lenticular region 54C. With this configuration, the divergence angle θ (refraction amount) of the outermost light ray Lz can be reduced, and the light ray Lz can be made to pass through the liquid crystal display panel 18. The luminance of the virtual image in the present embodiment is shown in FIG. 17, and the luminance of the third comparative example in which the curvatures of all the cylindrical lens portions are the same is shown in FIG. 16. Comparing FIG. 16 and FIG. 17, the luminances of the outer ends E1 and E2 in the left-right direction of the virtual image of the present embodiment shown in FIG. 17 can be made higher than the luminances of the outer ends E1 and E2 in the left-right direction of the virtual image of the third comparative example shown in FIG. 16. Therefore, in the present embodiment, the variation in the luminance of the virtual image can be made smaller than in the third comparative example.

[0034] Next, the background leading to the configuration of the Fresnel regions 54L and 54R according to the present embodiment will be described. As shown in FIGS. 18 and 19, in the fourth comparative example, the ideal optical surface 190 of the toroidal lens has different curvatures in the X and Y directions and has a curved surface that forms an elliptical contour La. In the optical surface 190, as shown in FIG. 20, it is assumed that Fresnel ridges 194 are formed on concentric circles centered on the lens center point 190C. In this case, the height difference in each ridge 194 tends to be large. For example, as indicated by arrow J1 in FIG. 20, ridge 194a is lower from the highest position PH to a position straddling two contour lines La. Therefore, in the present embodiment, as shown in FIG. 9, the center points O1 and O2 are shifted in the X direction between each ridge 54Y in the Fresnel region 54L and each ridge 54Y in the Fresnel region 54R. As a result, as shown in FIG. 21, since each ridge 54Y follows the contour line La, the height difference between each ridge 54Y can be reduced. Thereby, the curvature of each ridge 54Y is reduced, and as shown in FIG. 9, the end face width W of the Fresnel regions 54L and 54R can be reduced. The end face width W is the amplitude in the X direction of the ridge 54Y closest to the toroidal region 54T. Therefore, by reducing the end face width W, it is possible to suppress the formation of the ridge 54Y so as to straddle a plurality of contour lines, and the height difference between each ridge 54Y can be reduced. Further, thereby, as shown in FIG. 9, the angle α of the corner portion close to the toroidal region 54T of the Fresnel regions 54L and 54R can be reduced.

[0035] Next, a method for manufacturing the third lens 53 will be described. As shown in FIG. 22, the third lens 53 is manufactured by a mold 300. The mold 300 includes a lower mold 301 which is an example of a first mold type, and an upper mold 302 which is an example of a second mold type. The lower mold 301 is provided at a position facing the incident surface 54i of the third lens 53 formed in the cavity 308 of the mold 300. The upper mold 302 is provided at a position facing the exit surface 54o of the third lens 53 formed in the cavity 308 of the mold 300. The upper mold 302 is configured to be movable so as to approach or separate from the lower mold 301. The upper mold 302 includes first to third divided members 303 to 305 divided in the XY direction. The first dividing member 303 is a member for forming the Fresnel region 54L of the third lens 53. The second dividing member 304 is a member for forming the Fresnel region 54R of the third lens 53. The third dividing member 305 is a member for forming the toroidal region 54T of the third lens 53.

[0036] As shown in FIG. 23, the boundary line Lb between the third dividing member 305 and the first and second dividing members 303, 304 curves so as to pass near the boundary between the toroidal region 54T and the Fresnel regions 54L, 54R. A parting line 54P is formed on the third lens 53 along the boundary line Lb between the third dividing member 305 and the first and second dividing members 303, 304. The parting line 54P refers to a linear convex portion formed on the third lens 53 injection-molded by dividing the third dividing member 305 and the first and second dividing members 303, 304.

[0037] For example, as shown in FIG. 11, the parting line 54P is located at the apex of the peak portion 54Y1 at the position closest to the toroidal region 54T in each of the Fresnel regions 54L, 54R. The inclined surface of the peak portion 54Y1 constitutes a part of the toroidal region 54T. The parting line 54P extends along the apex of the peak portion 54Y1.

[0038] (Effect) According to the embodiment described above, the following effects are obtained. (1-1) The third lens 53, which is an example of a lens that diffuses light from the light source 19 toward the liquid crystal display panel 18, which is an example of a display panel, has a toroidal region 54T having a toroidal surface that curves in the X direction, which is an example of a first direction, and the Y direction, which is an example of a second direction, along the surface direction of the third lens 53 and intersects each other, and Fresnel regions 54L, 54R formed on both sides of the toroidal region 54T in the X direction and having a Fresnel lens shape. According to this configuration, by forming the Fresnel regions 54L and 54R on both sides of the toroidal region 54T, it is possible to reduce the thickness while maintaining the light diffusion angle of the third lens 53.

[0039] (1-2) The third lens 53 is formed on the back surface of the surface on which the toroidal region 54T and the Fresnel regions 54L and 54R of the third lens 53 are formed, includes a plurality of cylindrical lens portions 54S that extend along the Y direction and are arranged in the X direction. The curvature of the cylindrical lens portion 54S corresponding to the toroidal region 54T among the plurality of cylindrical lens portions 54S is formed larger than the curvature of the cylindrical lens portion 54S corresponding to the Fresnel regions 54L and 54R among the plurality of cylindrical lens portions 54S. According to this configuration, compared with the configuration in which all the curvatures of each cylindrical lens portion 54S are the same, the diffusion angle θ of the outermost light ray Lz (see FIG. 5) can be maintained to match the size of the liquid crystal display panel 18, and it is suppressed that the light ray Lz exceeds the liquid crystal display panel 18, and it is suppressed that the light from the light source 19 is wasted.

[0040] (1-3) The head-up display device 100 includes a third lens 53, a light source 19, and a liquid crystal display panel 18 that receives the light from the light source 19 transmitted through the third lens 53 and generates display light L. According to this configuration, it is possible to reduce the size of the head-up display device 100 through the thinning of the third lens 53. Further, since the diffusion angle θ of the light transmitted through the third lens 53 is maintained even if the third lens 53 is thin, the size of the virtual image V displayed by projecting the display light L onto the windshield 201, which is an example of the projection member, can be maintained.

[0041] (2-1) The third lens 53 has an emitting surface 54o which is an example of an optical surface showing optical characteristics symmetric with respect to the lens center point 53D through which the central ray of light from the light source 19 passes. The emitting surface 54o is formed in a range including the lens center point 53D, and has a toroidal region 54T which is an example of a non-Fresnel region curved about the lens center point 53D, and Fresnel regions 54L and 54R which are examples of the first and second Fresnel regions sandwiching the toroidal region 54T and having a Fresnel lens shape. The Fresnel region 54L has ridges 54Y which are examples of a plurality of first ridges arranged at regular intervals K from a center point O1 which is an example of a first center point located on the Fresnel region 54R side with respect to the lens center point 53D, along concentric arcs centered on the center point O1. The Fresnel region 54R has ridges 54Y which are examples of a plurality of second ridges arranged at regular intervals K from a center point O2 which is an example of a second center point located on the Fresnel region 54L side with respect to the lens center point 53D, along concentric arcs centered on the center point O2. According to this configuration, as described in (1-1) above, the third lens 53 can be made thinner. Also, the end face width W (see FIG. 9) of the Fresnel regions 54L and 54R can be reduced. Thereby, the height difference between the ridges 54Y of the Fresnel regions 54L and 54R can be reduced. Here, the third lens 53 is manufactured by a mold 300. For this reason, when the height difference between the ridges 54Y is small, the manufacture of the mold 300 and thus the third lens 53 becomes easy.

[0042] (2-2) The toroidal region 54T is curved with different curvatures along the X direction in which the Fresnel regions 54L and 54R are arranged and the Y direction intersecting the X direction. The toroidal region 54T is formed longer and with a greater curvature in the X direction than in the Y direction. According to this configuration, since the Fresnel regions 54L and 54R are positioned so as to sandwich the toroidal region 54T in the X direction, the height difference between the ridges 54Y of the Fresnel regions 54L and 54R can be reduced as compared with a configuration in which the Fresnel regions 54L and 54R are positioned so as to sandwich the toroidal region 54T in the Y direction.

[0043] (2-3) The center point O1 is located within the Fresnel region 54R. The center point O2 is located within the Fresnel region 54L. According to this configuration, the end face width W of the Fresnel regions 54L and 54R, and thus the height difference of each ridge portion 54Y of the Fresnel regions 54L and 54R, can be reduced.

[0044] (3-1) The third lens 53 includes a lens center point 53D through which the central ray of light from the light source 19 passes, a toroidal region 54T which is an example of a non-Fresnel region having a curved surface shape, Fresnel regions 54L and 54R located sandwiching the toroidal region 54T, and a parting line 54P formed between the toroidal region 54T and the Fresnel regions 54L and 54R. According to this configuration, it is suppressed that the parting line 54P crosses the toroidal region 54T and the Fresnel regions 54L and 54R. Therefore, variations in the light intensity transmitted through the third lens 53 can be suppressed. In particular, when the third lens 53 is applied to the head-up display device 100, the display quality of the virtual image V can be improved.

[0045] (3-2) The Fresnel regions 54L and 54R and the toroidal region 54T are arranged in the X direction which is an example of the first direction. The Fresnel regions 54L and 54R are each arranged in the X direction and have a plurality of ridge portions 54Y that are curved and extend in the Y direction. The parting line 54P is located at the apex of the ridge portion 54Y at the position closest to the toroidal region 54T in each of the Fresnel regions 54L and 54R. According to this configuration, by forming the parting line 54P at the apex of the ridge portion 54Y, the apex of the ridge portion 54Y can be made sharper. Thereby, variations in the light intensity transmitted through the third lens 53 can be suppressed.

[0046] (3-3) The mold 300 for manufacturing the third lens 53 includes first and second split members 303 and 304 for forming the Fresnel regions 54L and 54R of the third lens 53, and a third split member 305 for forming the toroidal region 54T. According to this configuration, by dividing the mold 300 into the first to third divided members 303 to 305, the parting line 54P can be formed between the toroidal region 54T and the Fresnel regions 54L and 54R.

[0047] Note that the present disclosure is not limited to the above embodiments and drawings. Modifications (including deletion of components) can be appropriately made without changing the gist of the present disclosure. An example of a modification will be described below.

[0048] (Modification example) In the above embodiment, the curvature of each cylindrical lens portion 54S in the lenticular regions 54A and 54B was the same, and the curvature of each cylindrical lens portion 54S in the lenticular region 54C was the same. However, the curvature of each cylindrical lens portion 54S in the lenticular regions 54A, 54B, and 54C may be formed so as to gradually decrease from the central portion toward the outside in the X direction. In this case, the curvature of the cylindrical lens portion 54S located on the outermost side in the X direction becomes the smallest. According to this configuration, in the Fresnel regions 54L and 54R, the diffusion angle θ of the light ray Lz increases as it goes toward the outside, and the light ray Lz is likely to deviate from the liquid crystal display panel 18. Therefore, by gradually changing the curvature of the cylindrical lens portion 54S, the illumination light can be efficiently irradiated onto the liquid crystal display panel 18.

[0049] In the above embodiment, the toroidal region 54T is curved concave along the X direction and convex along the Y direction. However, it is not limited to this, and it may be curved concave in both the X direction and the Y direction, or may be curved convex in both the X direction and the Y direction. Also, the toroidal region 54T may be curved convex along the X direction and concave along the Y direction.

[0050] In the above-described embodiment, the center point O1 was located within the Fresnel region 54R, and the center point O2 was located within the Fresnel region 54L, but it is not limited thereto. For example, the center points O1 and O2 may be located within the toroidal region 54T, or may be located outside the third lens 53 in the X direction. Also, the center points O1 and O2 may be provided at positions shifted from the lens center point 53D in the Y direction. Also, the third lens 53 may be provided with the front and back reversed.

[0051] In the above-described embodiment, the toroidal region 54T was formed to be longer and have a greater curvature in the X direction than in the Y direction, but it is not limited thereto, and it may be formed to be longer in the Y direction than in the X direction, or may be formed to have a greater curvature in the Y direction than in the X direction. Furthermore, the toroidal region 54T may be formed to have the same length in the X direction and the Y direction, or may be formed to have the same curvature in the X direction and the Y direction.

[0052] In the above-described embodiment, the Fresnel regions 54L and 54R were arranged so as to sandwich the toroidal region 54T in the X direction, but it is not limited thereto, and they may be arranged so as to sandwich the toroidal region 54T in the Y direction. Also, the Fresnel regions 54L and 54R may be arranged so as to sandwich the toroidal region 54T from both the X direction and the Y direction.

[0053] In the above-described embodiment, the first to third lenses 51 to 53 were formed in a rectangular plate shape, but it is not limited thereto, and for example, they may be formed in a square, circular, elliptical or polygonal plate shape. In the above-described embodiment, the head-up display device 100 may include a plane mirror or a concave mirror that reflects the display light L from the display unit 10 toward the concave mirror 20.

[0054] In the above-described embodiment, the contour line La of the optical surface 190 has shown an elongated shape in the short-side direction of the optical surface 190. However, the contour line La may not be as elongated as shown in the drawing and may have a shape closer to a circle. In this case, the highest position of the third lens does not appear near the center in the short-side direction of the optical surface 190 as shown in FIG. 20, and may appear on the long side (near the end face located in the second direction). Conversely, the contour line La may show a more elongated elliptical shape.

[0055] In the above-described embodiment, the head-up display device 100 was mounted on the vehicle 200. However, it may be mounted not only on the vehicle 200 but also on other vehicles such as airplanes and ships. The projection member on which the display light L is projected is not limited to the windshield 201 and may be a dedicated combiner.

Description of Reference Numerals

[0056] 10 Display unit 11 Backlight unit 13 Display panel unit 14 First case body 15 Second case body 16 Substrate 17 Light diffusion member 18 Liquid crystal display panel 19 Light source 20 Concave mirror 30 Housing 30c Opening 31 Window portion 32 Fitting hole portion 40 Heat dissipation member 51~53 First to third lenses 51a Convex lens portion 52a,52b,54S Cylindrical lens portions 52c Outer peripheral frame portion 52i,54i Incident surface 52o,54o Exit surface 53,153,253 Third lens 53D,190C Lens center point 153o,253o Light exit surface 54 Lens main body portion 54A, 54B, 54C lenticular regions 54L, 54R Fresnel regions 54P parting line 54T toroidal region 54Y, 54Y1, 194, 194a peak portions 541 first side 542 second side 55 outer frame portion 55a spacer 55b pin through-hole portion 55c convex plate portion 100 head-up display device 190 optical surface 200 vehicle 201 windshield 300 mold 301 lower mold 302 upper mold 303 - 305 first - third divided members 308 cavity θ diffusion angle K constant interval L display light O1, O2 center points P1 lowest position P2, PH highest positions E1, E2 ends V virtual image W end face width La contour line BL1, BL2, Lb boundary lines Lz light ray

Claims

1. A lens that diffuses light from a light source toward a display panel, having a toroidal region with toroidal surfaces that curve respectively in a first direction and a second direction along the surface direction of the lens and intersecting each other, a Fresnel region formed on both sides of the toroidal region of the lens in the first direction and having a Fresnel lens shape, formed on the back surface of the surface on which the toroidal region and the Fresnel region of the lens are formed, including a plurality of cylindrical lens portions that extend along the second direction and are arranged in the first direction, the curvature of the cylindrical lens portion corresponding to the toroidal region among the plurality of cylindrical lens portions is formed to be larger than the curvature of the cylindrical lens portion corresponding to the Fresnel region among the plurality of cylindrical lens portions, Lens.

2. the curvature of the plurality of cylindrical lens portions is formed to gradually decrease from the center of the lens toward the outside in the first direction, The lens according to claim 1.

3. The lens according to claim 1 or 2, the light source, and the display panel that receives the light from the light source transmitted through the lens and generates display light. Head-up display device.

Images