Display device and input apparatus

Abstract

To suppress an increase in size and suppress an increase in a production cost in a display device that displays images using holography.SOLUTION: A display device 10 includes a light source 11, a shaping optical system 12 that shapes light source light Ls emitted from the light source 11, and a hologram element 13 that reproduces an image IM using the light source light Ls shaped by the shaping optical system 12. The hologram element 13 has an incident surface 13s on which the light source light Ls shaped by the shaping optical system 12 is incident. The image IM is reproduced at a position separated from the hologram element 13 in a first direction D1 perpendicular to the incident surface 13s. The light source light Ls includes light having a wavelength λc shorter than the wavelength λr of the light used to produce the hologram element 13.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a display device and an input device.

Background Art

[0002] For example, as disclosed in Patent Document 1, a display device that displays an image using holography is known. The display device irradiates a hologram element with light source light emitted from a light source to display an image recorded on the hologram element. The hologram element has an incident surface on which the light source light is incident.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the display device of Patent Document 1, the light source is disposed at a position away from the hologram element in a direction orthogonal to the incident surface of the hologram element. The display device includes a portion protruding in a direction orthogonal to the incident surface of the hologram element, and thus becomes large-sized.

[0005] From the viewpoint of suppressing the enlargement of the display device, it is conceivable to use a hologram element capable of reproducing an image with light having a large incident angle on the incident surface. However, the production cost of a display device including such a hologram element increases. An object of the present disclosure is to suppress the enlargement and suppress an increase in production cost in a display device that displays an image using holography.

Means for Solving the Problems

[0006] A display device according to an embodiment of the present disclosure includes a light source, and A shaping optical system that shapes the light source light emitted by the light source, A hologram element that reproduces an image with the light source light shaped by the shaping optical system, and The hologram element has an incident surface on which the light source light shaped by the shaping optical system is incident, The image is reproduced at a position separated from the hologram element in a first direction orthogonal to the incident surface, The light source light includes light having a wavelength shorter than the wavelength of the light used for manufacturing the hologram element.

Advantages of the Invention

[0007] According to the present disclosure, in a display device that displays an image using holography, an increase in size can be suppressed, and an increase in production cost can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0009] One embodiment according to the present disclosure relates to the following [1] to

[15] .

[0010] [1] A light source, A shaping optical system that shapes the light source light emitted by the light source, A hologram element that reproduces an image with the light source light shaped by the shaping optical system, and The hologram element has an incident surface on which the light source light shaped by the shaping optical system is incident, The image is reproduced at a position separated from the hologram element in a first direction orthogonal to the incident surface, The light source light includes light having a wavelength shorter than the wavelength of the light used for manufacturing the hologram element, a display device.

[0011] [2] The first direction is inclined or orthogonal to the vertical direction by 45° or more, The shaping optical system is located below the hologram element, the display device of [1].

[0012] [3] The light source light is monochromatic light, the display device of [1] or [2].

[0013] [4] The shaping optical system includes a lens, The optical axis of the lens is inclined toward the hologram element with respect to the first direction, the display device according to any one of [1] to [3].

[0014] [5] A plate-like member overlapping the light source, the shaping optical system, and the hologram element, The plate-like member has a first region overlapping the light source and the shaping optical system and a second region overlapping the hologram element, The visible light transmittance of the plate-like member in the first region is lower than the visible light transmittance of the plate-like member in the second region, the display device according to any one of [1] to [4].

[0015] [6] The visible light transmittance of the plate-like member in the first region is 50% or less, the display device of [5].

[0016] [7] The plate-like member is located between the hologram element and the image in the first direction, the display device of [5] or [6].

[0017] [8] The image includes an intersection portion that intersects the plate-like member, the display device of [5] or [6].

[0018] [9] The distance between the hologram element and the plate-like member in the first direction is 10 mm or less, the display device of any one of [5] to [8].

[0019]

[10] It includes a support portion that supports the light source, the shaping optical system, and the hologram element, The plate-like member is disposed facing the support portion in the first direction, the display device of any one of [5] to [9].

[0020]

[11] The support portion is a housing that opens in the first direction, The plate-like member covers the opening, the display device of

[10] .

[0021]

[12] The support portion includes a display, the display device of

[10] .

[0022]

[13] The plate-like member has a first surface and a second surface opposite to the first surface, The first direction is inclined with respect to either one of the direction orthogonal to the first surface and the direction orthogonal to the second surface, the display device of any one of [5] to

[12] .

[0023]

[14] It includes a light shielding plate capable of absorbing the light source light reflected on the incident surface of the hologram element, the display device of any one of [1] to

[13] .

[0024]

[15] Any one of the display devices [1] to

[14] , and a sensor that detects an object approaching or approaching the image, and an input device.

[0025] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object. In addition, components shown in some of the drawings may be omitted in other drawings.

[0026] Terms such as "plate", "sheet", and "film" are not distinguished from each other only by the difference in name. "Plate-like" may be referred to as "sheet-like" or "film-like". A "plate-like member" may be referred to as a "sheet-like member" or a "film-like member". A "light-shielding plate" may be referred to as a "light-shielding sheet" or a "light-shielding film".

[0027] Terms such as "orthogonal", "parallel", and "flush" for specifying shape, geometric conditions, and their degrees are not limited to strict meanings. These terms are interpreted to include ranges where similar functions can be expected.

[0028] The directions common among the drawings are indicated by arrows with the same reference numerals in each drawing. In each direction, the tip side of the arrow is the first side. In each direction, the side opposite to the first side, that is, the base end side of the arrow is the second side. An arrow pointing from the back to the front of the paper in a direction orthogonal to the paper surface is indicated by a symbol with a dot in a circle, as shown in FIG. 3 for example.

[0029] FIGS. 1 to 6 are diagrams for explaining an embodiment. FIG. 1 shows a schematic configuration of the display device 10. FIGS. 2 and 3 show a specific configuration of the display device 10. In FIGS. 2 and 3, the input device 1 is configured by the display device 10 and the sensor 5 attached to the display device 10.

[0030] The display device 10 includes a light source 11, a shaping optical system 12, and a hologram element 13. The light source 11 emits source light Ls. The shaping optical system 12 shapes the source light Ls emitted by the light source 11. The hologram element 13 has an incident surface 13s on which the source light Ls is incident. The hologram element 13 displays an image IM by the source light Ls shaped by the shaping optical system 12. The illustrated hologram element 13 records the image IM as interference fringes. The hologram element 13 reproduces the recorded image IM by the source light Ls.

[0031] The display device 10 shown in FIG. 1 includes a plate-like member 20 that overlaps the light source 11, the shaping optical system 12, and the hologram element 13 from the first direction D1. In the illustrated display device 10, the hologram element 13 and the plate-like member 20 face each other in the first direction D1. The first direction D1 is a direction orthogonal to the incident surface 13s of the hologram element 13. The "direction orthogonal to the incident surface 13s" is, as shown in FIG. 1, the direction in which a line segment that perpendicularly intersects the incident surface 13s extends in the hologram element 13 observed globally.

[0032] The plate-like member 20 has a first surface 20a and a second surface 20b opposite to the first surface 20a. The plate-like member 20 forms the outer surface of the display device 10 on the first surface 20a. The plate-like member 20 faces the hologram element 13 on the second surface 20b. The first direction D1 may be parallel to a direction NP1 orthogonal to the first surface 20a of the plate-like member 20. The first direction D1 may be parallel to a direction NP2 orthogonal to the second surface of the plate-like member 20.

[0033] The light source 11 emits the light source light Ls. The light source 11 may be a laser light source that emits laser light as the light source light Ls. The light source 11 may be a light emitting diode (LED). When the light source 11 is a light emitting diode (LED), the cost of the light source 11 can be reduced as compared with when the light source 11 is a laser light source. Thereby, when the display device 10 includes a light emitting diode as the light source 11, the manufacturing cost of the display device 10 can be reduced. The light source light Ls includes a wavelength at which the hologram element 13 can reproduce the image IM. The light source light Ls is preferably monochromatic light. Note that the “monochromatic light” means light having one peak in the wavelength range of 300 nm or more and 780 nm or less in the spectrum of the light source light Ls.

[0034] The shaping optical system 12 shapes the light source light Ls emitted from the light source 11. The illustrated shaping optical system 12 changes the traveling direction of the light source light Ls. The light source light Ls shaped by the shaping optical system 12 travels toward the hologram element 13. The light source light Ls shaped by the shaping optical system 12 and traveling toward the hologram element 13 may travel through the air. The shaping optical system 12 includes a lens 50. The lens 50 can be a convex lens or a concave lens. In particular, by using a Fresnel lens, the size of the lens can be reduced.

[0035] The hologram element 13 shown in FIG. 1 is plate-shaped. The illustrated plate-shaped hologram element 13 has a thickness direction in the first direction D1, a longitudinal direction in the second direction D2, and a width direction in the third direction D3. The third direction D3 is a direction orthogonal to both the first direction D1 and the second direction D2.

[0036] The hologram element 13 is manufactured by recording interference fringes on a photosensitive hologram material. Information regarding the image of the display target and information regarding the position of the display target with respect to the hologram material are recorded in the interference fringes. The interference fringes are recorded by applying reference light and object light to the hologram material. The object light includes reflected light and scattered light from the display target to be displayed as the image IM. The reference light and the object light have coherence with each other. As such reference light and object light, light emitted from the same light source and split by a beam splitter such as a half mirror may be used. The object light may be formed by applying one of the two split lights to the display target.

[0037] The light source of the light used for manufacturing the hologram element 13 is a laser light source. That is, the light used for manufacturing the hologram element 13 is laser light.

[0038] In the hologram material, the interference fringes are recorded as a refractive index distribution or a transmittance distribution. That is, the hologram element 13 is a volume hologram.

[0039] In the display device 10, the light source light Ls shaped by the shaping optical system 12 is irradiated onto the interference fringes. When the light source light Ls includes the reproduction light Lc that satisfies the diffraction condition, that is, when the light source light Ls includes the reproduction light Lc that satisfies the Bragg condition, the reproduction light Lc diffracts in the hologram element 13. The diffracted light Ld diffracted in the hologram element 13 reproduces the image IM recorded in the interference fringes.

[0040] The image IM may be two-dimensional. The image IM may be three-dimensional. The display device 10 in FIG. 2 described later displays a two-dimensional image IM.

[0041] In the illustrated display device 10, the image IM is reproduced by the light source light Ls reflected by the hologram element 13. That is, the illustrated hologram element 13 is a reflective hologram. In the illustrated hologram element 13, the diffracted light Ld is emitted from the incident surface 13s of the light source light Ls. Not limited to the illustrated example, the image IM may be reproduced by the light source light Ls that has passed through the hologram element 13. That is, the hologram element 13 may be a transmissive hologram.

[0042] In the illustrated display device 10, the plate-like member 20 covers the light source 11, the shaping optical system 12, and the hologram element 13 from the first side in the first direction D1. The plate-like member 20 has a first region 201 that overlaps the light source 11 and the shaping optical system 12 from the first direction D1, and a second region 202 that overlaps the hologram element 13 from the first direction D1. In the illustrated display device 10, the first region 201 and the second region 202 are adjacent to each other in the second direction D2.

[0043] In the illustrated plate-like member 20, the visible light transmittance in the first region 201 is smaller than the visible light transmittance in the second region 202. As a result, when observing the light source 11, the shaping optical system 12, and the hologram element 13 through the plate-like member 20, the light source 11 and the shaping optical system 12 are less likely to be observed than the hologram element 13. The visible light transmittance of the plate-like member 20 in the first region 201 may be 50% or less, or may be 1% or less. The lower limit value of the visible light transmittance of the plate-like member 20 in the first region 201 is not particularly limited. The visible light transmittance of the plate-like member 20 in the first region 201 may be 0% or more. The visible light transmittance of the plate-like member 20 in the second region 202 may be 20% or more, or may be 50% or more. The upper limit value of the visible light transmittance of the plate-like member 20 in the second region 202 is not particularly limited. The visible light transmittance of the plate-like member 20 in the second region 202 may be 100% or less, or may be 80% or less.

[0044] The visible light transmittance is specified as the average value of the total light transmittance at each wavelength when measured every 1 nm within the range of 380 nm or more and 780 nm or less using a spectrophotometer (UV-3600i Plus manufactured by Shimadzu Corporation, compliant with JIS K0115). When the transmission direction is not particularly defined during the measurement of the visible light transmittance, the incident angle is set to 0°. The incident angle is the angle formed by the traveling direction of the incident light with respect to the normal direction to the incident surface and has a value less than 90°.

[0045] For the measurement of the total light transmittance, a D65 light source is used. Prior to the measurement of the total light transmittance, the light source is turned on for 15 minutes. In the measurement of the total light transmittance, the incident angle of the light emitted from the D65 light source to the measurement target is set to 0°. The test environment when measuring the total light transmittance is set to a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The total light transmittance is expressed as a percentage value in units of %. The measurement target for the total light transmittance is placed in the test environment for 16 hours before the start of the test. Other measurement conditions when measuring the total light transmittance follow JIS K7361-1:1997.

[0046] Next, mainly referring to FIGS. 2 and 3, the specific configuration of the input device 1 including the display device 10 will be described. The input device 1 shown in FIGS. 2 and 3 includes a display device 10 and a sensor 5. The display device 10 displays an image IM. The sensor 5 detects an object approaching or approaching the image IM.

[0047] The illustrated input device 1 is installed in a building 100. The building 100 may include stores such as restaurants, bookstores, clothing stores, and supermarkets. The input device 1 applied to a store may be a device for inputting information related to products. The input device 1 applied to a store may be a device for inputting information related to the services provided in the store. The input device 1 applied to a store may be a device for inputting information related to payment. The input device 1 may be applied to a moving body such as an elevator or an automobile.

[0048] The input device 1 may be installed in a state inclined by 45° or more with respect to the horizontal plane. As shown in FIGS. 2 and 3, the input device 1 may be installed in a state orthogonal to the horizontal plane. In other words, the input device 1 may be installed vertically. In FIGS. 2 and 3, the second direction D2 is a direction parallel to the vertical direction. In FIGS. 2 and 3, the second direction D2 is a direction parallel to the vertical and horizontal directions of the paper surface. Therefore, in FIGS. 2 and 3, the vertical direction is a direction parallel to the vertical and horizontal directions of the paper surface. The first side in the second direction D2 is the upper side, that is, the upper side in the vertical direction. The second side in the second direction D2 is the lower side, that is, the lower side in the vertical direction. In the illustrated example, the plane orthogonal to the second direction D2 is the horizontal plane. In the illustrated display device 10, the first direction D1 is orthogonal to the vertical direction.

[0049] In the display device 10 installed in a state inclined by 45° or more with respect to the horizontal plane, the hologram element 13 has, as shown in FIG. 3, an upper end portion 131 and a lower end portion 132. The upper end portion 131 of the illustrated hologram element 13 is the end portion on the first side in the second direction D2 of the hologram element 13. The lower end portion 132 of the illustrated hologram element 13 is the end portion on the second side in the second direction D2 of the hologram element 13. In the illustrated hologram element 13, the upper end portion 131 and the lower end portion 132 each extend in the third direction D3.

[0050] In the display device 10 shown in FIG. 3, among the light source 11, the shaping optical system 12, and the hologram element 13, the light source 11 is located at the lowest position. Among the light source 11, the shaping optical system 12, and the hologram element 13, the hologram element 13 is located at the uppermost position. In the illustrated display device 10, the shaping optical system 12 is located below the hologram element 13. When the light source 11 is located below the hologram element 13, the light source 11 is located below the upper end portion of the hologram element 13. When the light source 11 is located below the hologram element 13, the light source 11 may be located below the lower end portion of the light source 11 as shown in FIG. 3. When the shaping optical system 12 is located below the hologram element 13, the shaping optical system 12 is located below the upper end portion of the hologram element 13. When the shaping optical system 12 is located below the hologram element 13, the shaping optical system 12 may be located below the lower end portion of the hologram element 13 as shown in FIG. 3.

[0051] The display device 10 shown in FIG. 3 includes a light shielding plate 14 arranged to face the shaping optical system 12 in the second direction D2. Among the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14, the light shielding plate 14 is located at the uppermost position. As will be described later, the light shielding plate 14 has visible light shielding properties. The light shielding plate 14 can absorb the light source light Ls reflected at the incident surface 13s. The light shielding plate 14 may be omitted from the display device 10.

[0052] The input device 1 applied to the building 100 may be installed on the wall of the building 100. As shown in FIG. 2, in the building 100, at least a part of the outer surface of the input device 1 and the wall surface of the building 100 may be flush. In the input device 1 shown in FIG. 2, a base portion 21, which will be described later, of the plate-like member 20 is flush with the wall surface of the building 100.

[0053] The display device 10 shown in FIG. 3 includes a support portion 15 that supports a light source 11, a shaping optical system 12, a hologram element 13, and a light shielding plate 14. In particular, the illustrated display device 10 includes a housing 16 as the support portion 15. That is, the illustrated support portion 15 is the housing 16. The illustrated housing 16 is open in the first direction D1. The housing 16 may be made of resin or metal. The illustrated display device 10 includes the housing 16, the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14 housed in the housing 16, and a plate-like member 20 that covers the opening of the housing 16.

[0054] In the example shown in FIGS. 2 and 3, the housing 16 includes a bottom plate portion 161 and side plate portions 162 extending in the first direction D1 from the bottom plate portion 161. The bottom plate portion 161 extends in the second direction D2 and the third direction D3. The third direction D3 is a direction orthogonal to both the first direction D1 and the second direction D2. The bottom plate portion 161 has a longitudinal direction in a direction parallel to the second direction D2. The side plate portion 162 has a width direction in a direction parallel to the third direction D3. The side plate portion 162 extends in the first direction D1 and a direction orthogonal to the first direction D1.

[0055] In the illustrated display device 10, the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14 are attached to the bottom plate portion 161 or the side plate portion 162. The bottom plate portion 161 restricts the movement of the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14 housed in the housing 16 in the first direction D1. The side plate portion 162 restricts the movement of the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14 housed in the housing 16 in a direction orthogonal to the first direction D1. In the illustrated housing 16, the side plate portion 162 includes a first side plate portion 162a facing each other in the second direction D2, that is, the vertical direction, and a second side plate portion 162b facing each other in the third direction D3.

[0056] In the illustrated display device 10, the light source 11 is attached to the lower one of the first side plate portions 162a facing each other in the second direction D2. The light source 11 attached to the first side plate portion 162a emits light source light Ls upward, that is, to the first side in the second direction D2. The light source 11 may be located at the central portion of the first side plate portion 162a in the first direction D1. The light source 11 may be located at the central portion of the first side plate portion 162a in the third direction D3.

[0057] In the illustrated display device 10, the shaping optical system 12 is attached to the bottom plate portion 161. The shaping optical system 12 may be attached to the plate-like member 20. The illustrated shaping optical system 12 may be attached to the second side plate portion 162b. The illustrated shaping optical system 12 is plate-shaped. The plate-shaped shaping optical system 12 extends in the third direction D3. Both ends of the plate-shaped shaping optical system 12 in the third direction D3 may be connected to each of the pair of second side plate portions 162b, respectively.

[0058] The shaping optical system 12 may include a lens 50. The lens 50 may be a convex lens. The shaping optical system 12 may be a Fresnel lens. By the shaping optical system 12 being a Fresnel lens, the dimensions of the shaping optical system 12 can be suppressed. In the illustrated display device 10, by the shaping optical system 12 being a Fresnel lens, the dimension (thickness) of the shaping optical system 12 in the second direction D2 is suppressed.

[0059] As shown in FIG. 3, the lens 50 may be disposed obliquely such that the optical axis 50s faces the hologram element 13 in the first direction D1. In other words, the optical axis 50s may be inclined with respect to the first direction D1 so as to approach the hologram element 13 in the first direction D1 as it moves away from the light source 11 in the traveling direction of the light source light Ls. The illustrated optical axis 50s approaches the hologram element 13 in the first direction D1 as it moves away from the light source 11 in the second direction D2. The illustrated optical axis 50s approaches the hologram element 13 in the first direction D1 as it approaches the hologram element 13 in the second direction D2. The illustrated optical axis 50s is inclined by an inclination angle θ l only with respect to the first direction D1.

[0060] In the examples shown in FIGS. 2 and 3, the hologram element 13 is plate-shaped. The plate-shaped hologram element 13 has a first surface 13a and a second surface 13b opposite to the first surface 13a. The direction orthogonal to the first surface 13a is parallel to the first direction D1. The hologram element 13 displays the image IM by the light shaped by the shaping optical system 12. The light shaped by the shaping optical system 12 is incident on the first surface 13a of the hologram element 13. That is, the first surface 13a serves as the incident surface 13s of the hologram element 13.

[0061] The hologram element 13 shown in FIGS. 2 and 3 includes a reflective hologram. In the illustrated hologram element 13, the diffracted light Ld that forms the image IM is emitted from the first surface 13a. The emission surface of the diffracted light Ld in the illustrated hologram element 13 is the same as the incident surface 13s of the hologram element 13.

[0062] With reference to FIG. 4, an example of a method for manufacturing the hologram element 13 shown in FIGS. 2 and 3 will be described. Specifically, with reference to FIG. 4, an example of a method for manufacturing a reflective volume hologram (Lippmann hologram) will be described.

[0063] As shown in Fig. 4, a hologram photosensitive material 40 and a display object OB to be displayed as an image IM are prepared. The display object OB is placed at the position where the image IM is to be displayed by the hologram element 13. In this state, the above-described object light Lo and reference light Lr are applied to the hologram photosensitive material 40. For the object light Lo and the reference light Lr, light source light emitted from the same light source and split by a beam splitter is used. A laser light source is used for fabricating the hologram element 13. That is, the object light Lo and the reference light Lr are laser lights. The object light Lo and the reference light Lr have a common single wavelength λ r and. The hologram photosensitive material 40 may contain one or more of a photopolymer, dichromated gelatin, and a photoresist.

[0064] In Fig. 4, the object light Lo is applied to the surface of the hologram photosensitive material 40 that forms the first surface 13a. In the illustrated example, the object light Lo is incident on the hologram photosensitive material 40 at an incident angle θ o . The incident angle θ o of the object light Lo is the angle between the direction perpendicular to the surface of the hologram photosensitive material 40 that forms the first surface 13a and the direction in which the object light Lo travels.

[0065] The incident angle θ o of the object light Lo may be 0° or more, or may be 10° or more. The incident angle θ o of the object light Lo may be 80° or less, or may be 70° or less. The incident angle θ r of the reference light Lr may be 30° or more, or may be 45° or more. The incident angle θ r of the reference light Lr may be 80° or less, may be 60° or less, or may be 50° or less.

[0066] In Fig. 4, the reference light Lr is applied to the surface of the hologram photosensitive material 40 that is opposite to the surface to which the object light Lo is applied, that is, the surface that forms the second surface 13b. In the illustrated example, the reference light Lr is incident on the hologram photosensitive material 40 at an incident angle θ r . The incident angle θ rIt is the angle between the direction orthogonal to the surface of the holographic photosensitive material 40 that comes to form the second surface 13b and the direction in which the reference light Lr travels.

[0067] When the object light Lo and the reference light Lr are applied, the holographic photosensitive material 40 forms interference fringes inside. By recording these interference fringes, the hologram element 13 is fabricated. The fabricated hologram element 13 includes a plurality of interference fringes 30 as shown in FIG. 5. The interference fringes 30 spread planar within the hologram element 13. When observing the cross section of the hologram element 13, the interference fringes 30 are observed as a plurality of linear streaks extending in the hologram element 13 as shown in FIG. 5. FIG. 5 shows a plurality of interference fringes 30 extending with a space d therebetween within the hologram element 13.

[0068] The interference fringes 30 may spread over a plane orthogonal to the first direction D1. In other words, the interference fringes 30 observed as linear streaks in the cross section of the hologram element 13 may extend in a direction parallel to the incident surface 13s of the hologram element 13. The interference fringes 30 may spread over a plane inclined with respect to the plane orthogonal to the first direction D1. In other words, the interference fringes 30 observed as linear streaks in the cross section of the hologram element 13 may extend in a direction inclined with respect to the direction in which the incident surface 13s of the hologram element 13 extends as shown in FIG. 5. In the cross section of the hologram element 13 shown in FIG. 5, the incident surface 13s extends in the second direction D2. In the illustrated hologram element 13, the interference fringes 30 extend in a direction inclined with respect to the second direction D2.

[0069] When the hologram element 13 is irradiated with light that satisfies the Bragg condition on the incident surface 13s, the image IM is reproduced. In the hologram element 13, diffraction occurs due to the light that satisfies the Bragg condition. The diffracted light emitted from the incident surface 13s due to diffraction forms the image IM. The Bragg condition is a condition regarding reflection in the interference fringes of the light traveling inside the hologram element 13. The Bragg condition is represented by the following formula (1). In formula (1), d is the interval between the interference fringes formed inside the hologram element 13. φ is the angle between the light traveling inside the hologram element 13 and the interference fringes. m is an arbitrary natural number. λ is the wavelength of the light traveling inside the hologram element 13. [Number]

[0070] FIG. 5 shows, as an example of light that satisfies the Bragg condition, the first reproduction light Lc1. The first reproduction light Lc1 has the same wavelength λ r as the wavelength λ c1 of the reference light Lr. That is, the wavelength λ c1 of the first reproduction light Lc1 is the same as the wavelength λ r of the light used for manufacturing the hologram element 13. The first reproduction light Lc1 is incident on the incident surface 13s at the same incident angle θ r as the incident angle θ c1 of the reference light Lr. The first reproduction light Lc1 shown in FIG. 5 is incident on the hologram element 13 at point A on the incident surface 13s.

[0071] The first reproduction light Lc1 shown in FIG. 5 is refracted at point A. The first reproduction light Lc1 refracted at point A travels inside the hologram element 13 so as to form an angle θ' c1 with the first direction D1. That is, the angle θ' c1 is the refraction angle of the first reproduction light Lc1. The incident angle θ c1 of the first reproduction light Lc1 and the refraction angle θ' c1The relationship between them is represented by the following formula (2) based on Snell's law. In formula (2), n is the refractive index in the medium until the first playback light Lc1 reaches point A. n' is the refractive index of the hologram element 13.

Number

[0072] Also, according to Snell's law, the wavelength λ in the medium until the first playback light Lc1 reaches point A c1 and the wavelength λ' of the first playback light Lc1 traveling in the hologram element 13 c1 The relationship between them is represented by the following formula (3). In formula (3), n is the refractive index in the medium until the first playback light Lc1 reaches point A. n' is the refractive index of the hologram element 13.

Number

[0073] The first playback light Lc1 shown in FIG. 5 has reached the interference fringes 30 at point O on the interference fringes 30. In the illustrated hologram element 13, as the Bragg condition, the relationship of the following formula (4) is satisfied. In formula (4), d is the interval of the interference fringes 30 formed in the hologram element 13. φ1 is the angle at point O between the first playback light Lc1 and the direction in which the interference fringes 30 extend. m1 is an arbitrary natural number. λ' c1 is the wavelength of the first playback light Lc1 traveling in the hologram element 13.

Number

[0074] In the hologram element 13 shown in FIG. 5, the first diffracted light Ld1 is formed by the reflected light in the interference fringes 30 of the first reproduction light Lc1 traveling through the hologram element 13. The first reproduction light Lc1 is reflected at the point O on the interference fringes 30. The first diffracted light Ld1 makes an angle φ1 with the interference fringes 30. When the first diffracted light Ld1 travels through the hologram element 13, it makes an angle θ' d1 with the first direction D1. The first diffracted light Ld1 exits the hologram element 13 at the point B on the incident surface 13s.

[0075] The first diffracted light Ld1 shown in FIG. 5 is refracted at the point B. The first diffracted light Ld1 exiting the hologram element 13 makes an angle θ d1 with the incident surface 13s. The angle θ d1 and the angle θ' d1 are related by the following equation (5) based on Snell's law described above. In equation (5), n' is the refractive index of the hologram element 13. n is the refractive index in the medium through which the first reproduction light Lc1 refracted at the point B travels.

Equation

[0076] FIG. 5 shows a triangle ABO formed by the points A, B, and O. In the triangle ABO, the angle (°) of ∠OAB is the value obtained by subtracting the angle θ' c1 (°) from 90 (°). In the triangle ABO, the angle (°) of ∠OBA is the value obtained by subtracting the angle θ' d1 (°) from 90 (°). In the triangle ABO, the angle of ∠AOB can be calculated from the angles of ∠OAB and ∠OBA. The angle φ1 shown in FIG. 5 is calculated as follows using the above-mentioned angle θ' c1 , angle θ' d1 . Also, the angle φ can be expressed using the following equation (6), and the above-mentioned equations (2) and (5), using the above-mentioned angle θ c1 and angle θ d1 .

Equation

[0077] The hologram element 13 shown in FIGS. 2 and 3 reproduces the image IM by the light source light Ls shaped by the shaping optical system 12. In the illustrated display device 10, the image IM is reproduced at a position separated from the hologram element 13 on the first side in the first direction D1. The illustrated hologram element 13 reproduces the image IM at a position farther from the hologram element 13 than the plate-like member 20 in the first direction D1. In the illustrated display device 10, the plate-like member 20 is located between the hologram element 13 and the image IM in the first direction D1.

[0078] In the display device 10 shown in FIGS. 2 and 3, the image IM is two-dimensional. The two-dimensional image IM spreads on a plane orthogonal to the first direction D1. As shown in FIG. 2, the image IM spreads in the second direction D2 and the third direction D3. The image IM is reproduced at a position separated from the display device 10 in the first direction D1. By displaying the two-dimensional image IM at such a position, the image IM is observed as if it floats from the outer surface of the input device 1 as shown in FIG. 2. In FIG. 2, a note-shaped image IM is displayed as the two-dimensional image IM.

[0079] In the display device 10 shown in FIG. 3, the light shielding plate 14 is installed farther from the shaping optical system 12 than the hologram element 13 in the second direction D2. The hologram element 13 is located between the shaping optical system 12 and the light shielding plate 14 in the second direction D2. The illustrated light shielding plate 14 is attached to the upper first side plate portion 162a among the first side plate portions 162a facing each other in the second direction D2. By being attached to the side plate portion 162a, the illustrated light shielding plate 14 faces the second direction D2. Note that the light shielding plate 14 may be omitted from the display device 10.

[0080] The light-shielding plate 14 has visible light-shielding properties. For a certain component of the display device 10 to have "visible light-shielding properties" means that the visible light transmittance of the component is 90% or less. The visible light transmittance of a certain component of the display device 10 having visible light-shielding properties may be 50% or less. In the components of the display device 10, the visible light transmittance is measured by the method described above.

[0081] The light-shielding plate 14 may absorb the light source light Ls that has not been diffracted by the hologram element 13. By the light-shielding plate 14 absorbing the light source light Ls, the display device 10 can be suppressed from displaying light other than the image IM. The light-shielding plate 14 may contain light-absorbing particles. The light-absorbing particles may be black pigments such as carbon black and titanium black.

[0082] In the display device 10 shown in FIGS. 2 and 3, the plate-like member 20 has a first surface 20a and a second surface 20b opposite to the first surface 20a. The first surface 20a forms the outer surface of the display device 10.

[0083] The plate-like member 20 shown in FIGS. 2 and 3 overlaps the light source 11, the shaping optical system 12, the hologram element 13, and the light-shielding plate 14 from the first direction D1. The illustrated plate-like member 20 faces the hologram element 13 in the first direction D1. The illustrated plate-like member 20 faces the hologram element 13 in a direction NP1 orthogonal to the first surface 20a of the plate-like member 20. The illustrated plate-like member 20 faces the hologram element 13 in a direction NP2 orthogonal to the second surface 20b of the plate-like member 20.

[0084] The distance DL between the hologram element 13 and the plate-like member 20 in the first direction D1 may be 10 mm or less, may be 8 mm or less, or may be 5 mm or less. The "distance DL between the hologram element 13 and the plate-like member 20 in the first direction D1" is the distance between the emission surface of the diffracted light Ld in the hologram element 13 and the portion of the plate-like member 20 that is farthest from the hologram element 13 in the first direction D1. In the display device 10 shown in FIGS. 2 and 3, the distance DL is the distance between the first surface 13a of the hologram element 13 and the first surface 20a of the plate-like member 20.

[0085] In the display device 10 shown in FIGS. 2 and 3, the plate-like member 20 has a first region 201 and a second region 202 adjacent to the first region 201 in the second direction D2. The illustrated first region 201 is located below the second region 202, that is, on the second side in the second direction D2. When the illustrated input device 1 is observed from the first direction D1, the area of the first region 201 is smaller than the area of the second region 202. In the illustrated display device 10, the image IM is displayed at a position overlapping the second region 202 in the first direction D1.

[0086] In the example shown in FIG. 3, the plate-like member 20 includes a base portion 21 and a light-shielding portion 22 overlapped on the base portion 21. The base portion 21 overlaps the light source 11, the shaping optical system 12, and the hologram element 13 from the first side in the first direction D1. The light-shielding portion 22 overlaps the light source 11 and the shaping optical system 12 from the first side in the first direction D1. The base portion 21 and the light-shielding portion 22 may be joined to each other in the first direction D1. In the illustrated plate-like member 20, the first region 201 is formed by the portion where the base portion 21 and the light-shielding portion 22 overlap in the first direction D1. In the illustrated plate-like member 20, the second region 202 is formed by the portion other than the portion where the base portion 21 and the light-shielding portion 22 overlap in the first direction D1.

[0087] In the plate-shaped member 20 shown in FIG. 3, the base portion 21 covers the opening of the housing 16 from the first side in the first direction D1. The base portion 21 forms the first surface 20a of the plate-shaped member 20. That is, the base portion 21 forms the outer surface of the display device 10. The base portion 21 forms the outer surface of the input device 1. The base portion 21 covers the light source 11, the shaping optical system 12, the hologram element 13, and the light shielding plate 14 from the first side in the first direction D1. The base portion 21 includes a portion located in the first region 201 of the plate-shaped member 20 and a portion located in the second region 202 of the plate-shaped member 20. The base portion 21 may be transparent. The base portion 21 may be made of resin. The base portion 21 may be made of glass.

[0088] For a certain component of the display device 10 to be "transparent" means that the visible light transmittance of the component is 50% or more. The visible light transmittance of the transparent component of the display device 10 may be 80% or more. In the components of the display device 10, the visible light transmittance is measured by the method described above.

[0089] In the plate-shaped member 20 shown in FIG. 3, the light shielding portion 22 partially covers the opening of the housing 16 from the first side in the first direction D1. The light shielding portion 22 covers the light source 11 and the shaping optical system 12 from the first side in the first direction D1. The portion of the light shielding portion 22 that covers the light source 11 and the shaping optical system 12 forms the first region 201 of the plate-shaped member 20. The light shielding portion 22 may be made of resin. The light shielding portion 22 may be made of glass. The light shielding portion 22 may be made of metal.

[0090] The light shielding portion 22 has visible light shielding properties. In the illustrated plate-shaped member 20, due to the light shielding portion 22 having visible light shielding properties, the visible light transmittance in the first region 201 is reduced. The light shielding portion 22 having visible light shielding properties can conceal the light source 11 and the shaping optical system 12 in the observation from the outer surface of the display device 10. The light shielding portion 22 having visible light shielding properties can suppress the emission of the light source light Ls in the first region 201. In the illustrated display device 10, the emission to the first side in the first direction D1 is suppressed.

[0091] In the illustrated input device 1, the sensor 5 detects an object approaching or approaching the image IM. The sensor 5 may be non-contact. That is, the object may be detected without contacting the sensor 5. The sensor 5 may detect the object in various ways. As an example of the detection method of the sensor 5, a capacitance method, an infrared method, an ultrasonic method, and an image recognition method can be mentioned, but other methods may also be used.

[0092] In the input device 1 shown in FIGS. 2 and 3, the sensor 5 is plate-shaped. The sensor 5 is provided in a portion that overlaps the second region 202 of the plate member 20 in the first direction D1. The sensor 5 is housed in the housing 16. The sensor 5 is located between the bottom plate portion 161 of the housing 16 and the hologram element 13 in the first direction D1.

[0093] FIG. 6 shows the layer structure of the sensor 5. The sensor 5 has a first surface 5a and a second surface 5b opposite to the first surface 5a. The illustrated sensor 5 includes a first electrode 51 and a second electrode 52 that overlaps the first electrode 51 in the first direction D1. The first electrode 51 and the second electrode 52 have conductivity. The sensor 5 may be electrically connected to an external control device (not shown) at the first electrode 51 and the second electrode 52.

[0094] The sensor 5 shown in FIG. 6 includes a base material 55 that supports the first electrode 51 and the second electrode 52. The base material 55 is located between the first electrode 51 and the second electrode 52 in the first direction D1. The base material 55 has insulation. The base material 55 may be transparent. The base material 55 may be made of resin or glass.

[0095] The illustrated sensor 5 detects an object by the capacitance method. In the illustrated sensor 5, an electric field is generated between the first electrode 51 and the second electrode 52. When an object approaches the image IM, the electric field between the first electrode 51 and the second electrode 52 changes. The sensor 5 detects such a change in the electric field as the approach of the object.

[0096] The first electrode 51 and the second electrode 52 may be transparent. The first electrode 51 and the second electrode 52 may be tin oxide-based thin films such as tin oxide (SnO2), antimony-doped tin oxide (ATO, Antimony Tin Oxide), and fluorine-doped tin oxide (FTO). The first electrode 51 and the second electrode 52 may be indium oxide-based thin films such as indium oxide, indium tin oxide (ITO, Indium Tin Oxide), and IZO (Indium Zinc Oxyde). The first electrode 51 and the second electrode 52 may be zinc oxide-based thin films such as zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO).

[0097] As shown in FIG. 6, the sensor 5 includes a cover 53 that protects the first electrode 51 or the second electrode 52. The cover 53 has insulating properties. The cover 53 may be made of resin or glass.

[0098] In the illustrated input device 1, the image IM overlaps the sensor 5 in the first direction D1. When the image IM is observed protruding from the outer surface of the input device 1, the user of the input device 1 can easily understand that the sensor 5 is non-contact type. In other words, the user of the input device 1 can easily understand that the illustrated input device 1 can detect an object in a state where it is not in contact with the sensor 5 as an external input.

[0099] In the illustrated input device 1, the display device 10 may display different images IM. The display device 10 may display the same image at different positions. In the display device 10, a plurality of images IM may be recorded in the hologram element 13. When the hologram element 13 is reproducing a certain image IM, the hologram element 13 may not need to reproduce other images IM. The image IM displayed by the display device 10 may change according to the detection result of the sensor 5. The image IM displayed by the display device 10 may be controlled by an external control device (not shown).

[0100] The operation of the input device 1 shown in FIG. 2 will be described.

[0101] The light source 11 emits the light source light Ls. The light source 11 may emit the light source light Ls based on a signal transmitted from an external control device (not shown). The light source 11 may stop emitting the light source light Ls based on a signal transmitted from an external control device.

[0102] The shaping optical system 12 shapes the light source light Ls emitted by the light source 11. The shaped light source light Ls travels toward the hologram element 13. In the illustrated display device 10, the light shaped by the shaping optical system 12 travels toward the hologram element 13 on the second side in the first direction D1. The light source light Ls shaped by the shaping optical system 12 and traveling toward the hologram element 13 may travel through the air.

[0103] In the illustrated display device 10, the shaping optical system 12 includes a lens 50. The optical axis 50s of the lens 50 is inclined toward the hologram element 13 with respect to the first direction D1. The lens 50 refracts the light source light Ls so as to travel along the optical axis 50s. By traveling along the illustrated optical axis 50s, the light source light Ls approaches the hologram element 13 as it moves away from the light source 11. Thereby, the illustrated shaping optical system 12 can easily shape the light source light Ls so as to travel toward the hologram element 13 in the first direction D1, that is, toward the second side in FIG. 3.

[0104] The light source light Ls shaped by the shaping optical system 12 enters the hologram element 13. The light source light Ls refracts at the incident surface 13s of the hologram element 13. In the display device 10 shown in FIGS. 2 and 3, when the light source light Ls traveling through the hologram element 13 includes the reproduction light Lc that satisfies the above-described Bragg condition, diffraction occurs in the hologram element 13. Diffracted light Ld is emitted from the diffracted hologram element 13. The diffracted light Ld reproduces the image IM recorded in the interference fringes as shown in FIGS. 2 and 3. In the example shown in FIG. 3, the image IM is reproduced at a position that is maximally separated from the hologram element 13 by a distance DR in the first direction D1.

[0105] By the way, a conventional display device that displays an image using holography includes a light source and a hologram element that displays an image by light from the light source. Generally, in order for the hologram element to reproduce an image, it is necessary to apply reproduction light that satisfies the Bragg condition to the hologram element. The light from the light source needs to include the reproduction light. The light from the light source needs to be incident on the hologram element at a certain incident angle in order to satisfy the Bragg condition. Note that the incident angle of the light from the light source is the angle between the light ray of the light from the light source and the direction perpendicular to the incident surface of the hologram element. The incident angle of the reproduction light is the angle between the light ray of the reproduction light and the direction perpendicular to the incident surface of the hologram element.

[0106] In a display device that displays an image using holography, a light source or a shaping optical system that shapes the light from the light source needs to be arranged at a position away from the hologram element in the direction perpendicular to the incident surface of the hologram element. Such a display device comes to include a portion that protrudes in the direction perpendicular to the incident surface. In the protruding portion, the thickness of the display device, that is, the length in the direction perpendicular to the incident surface of the hologram element, becomes larger than that of the portion other than the protruding portion. These days, although the application range of display devices that display images using holography is expanding, the application range of display devices having such a shape is limited.

[0107] In order to suppress the amount of protrusion of the light source of the display device, it is conceivable to increase the incident angle on the incident surface of the hologram element. In order to increase the incident angle of the reproduction light, the hologram element can be manufactured by irradiating a hologram photosensitive material with light having a large incident angle as reference light. However, when the incident angle on the hologram photosensitive material increases, the amount of reflected light that is reflected on the surface of the hologram photosensitive material among the light irradiated on the hologram photosensitive material increases. The reflected light does not contribute to the formation of the interference fringes of the hologram element. In manufacturing such a hologram element, the exposure time for the hologram photosensitive material can increase. As a result, when using a hologram element with a large incident angle of the reproduction light, problems such as deterioration of production efficiency and increase in production cost can occur.

[0108] In contrast, in the display device 10 shown in FIGS. 1 to 3, the wavelength λ of the reproduction light Lc c is different from the wavelength λ of the light used for fabricating the hologram element 13 r In particular, in the illustrated display device 10, the wavelength λ of the reproduction light Lc c is different from the wavelength λ of the light used for fabricating the hologram element 13 r and is shorter. In other words, the light source light Ls includes the reproduction light Lc having a wavelength λ r shorter than the wavelength λ of the light used for fabricating the hologram element 13 c .

[0109] FIG. 5 shows a second reproduction light Lc2 as reproduction light Lc having a wavelength shorter than the wavelength λ of the light used for fabricating the hologram element 13. Similar to the first reproduction light Lc1 described above, the second reproduction light Lc2 is light that satisfies the Bragg condition. The wavelength λ of the second reproduction light Lc2 r is shorter than the wavelength λ of the first reproduction light Lc1. The second reproduction light Lc2 is incident on the incident surface 13s at an incident angle θ c2 The second reproduction light Lc2 is incident on the hologram element 13 at a point A on the incident surface 13s c1 c2

[0110] The second reproduction light Lc2 shown in FIG. 5 is refracted at point A. The second reproduction light Lc2 refracted at point A travels through the hologram element 13 so as to form an angle θ' c2 with the first direction D1. That is, the angle θ' c2 is the refraction angle of the second reproduction light Lc2. The relationship between the incident angle θ c2 of the second reproduction light Lc2 and the refraction angle θ' c2 of the second reproduction light Lc2 is represented by the following formula (7) based on Snell's law. In formula (7), n is the refractive index in the medium until the second reproduction light Lc2 reaches point A. n' is the refractive index of the hologram element 13

Equation

[0111] Also, according to Snell's law, the wavelength λ in the medium until the second reproduction light Lc2 reaches point A c2 and the wavelength λ' of the second reproduction light Lc2 traveling in the hologram element 13 c2 The relationship between them is represented by the following formula (8). In formula (8), n is the refractive index in the medium until the second reproduction light Lc2 reaches point A. n' is the refractive index of the hologram element 13. [Number]

[0112] The second reproduction light Lc2 shown in FIG. 5 has reached the interference fringes 30 at point P on the interference fringes 30. In the illustrated hologram element 13, as the Bragg condition, the relationship of the following formula (9) is satisfied. In formula (9), d is the interval of the interference fringes 30 formed in the hologram element 13. φ2 is the angle at point P between the second reproduction light Lc2 and the direction in which the interference fringes 30 extend. m2 is an arbitrary natural number. λ' c2 is the wavelength of the second reproduction light Lc2 traveling in the hologram element 13. [Number]

[0113] In the hologram element 13 shown in FIG. 5, the second diffracted light Ld2 is formed by the reflected light in the interference fringes 30 of the second reproduction light Lc2 traveling in the hologram element 13. The second reproduction light Lc2 is reflected at point P on the interference fringes 30. The second diffracted light Ld2 makes an angle φ2 with the interference fringes 30. When the second diffracted light Ld2 travels in the hologram element 13, it makes an angle θ' d2 with the first direction D1. The second diffracted light Ld2 exits the hologram element 13 at point C on the incident surface 13s.

[0114] The second diffracted light Ld2 shown in FIG. 5 is refracted at point C. The second diffracted light Ld2 exiting the hologram element 13 makes an angle θ with the incident surface 13sd2 forms the angle θ d2 and the angle θ' d2 The relationship between them is expressed by the following formula (10) based on Snell's law described above. In formula (10), n' is the refractive index of the hologram element 13. n is the refractive index in the medium through which the second reproduced light Lc2 refracted at point C travels.

Equation

[0115] Figure 5 shows the triangle APO formed by point A, point O, and point P. In triangle APO, the angle of angle APO is angle φ2. The angle of angle AOP (°) is the value obtained by subtracting angle φ1 (°) from 180 (°). The angle of angle OAP is the angle obtained by subtracting angle θ' c2 from angle θ' c1 Based on these angles and the sum of the interior angles of triangle APO, the relationship among angle φ1, angle φ2, angle θ' c1 and angle θ' c2 is established as shown in the following formula (11).

Equation

[0116] In the above-mentioned formulas (4) and (9), the interval d of the interference fringes 30 is common. From formulas (4) and (9), the following relationship of formula (12) for d is derived. In formula (12), φ1 is the angle at point O between the first reproduced light Lc1 and the direction in which the interference fringes 30 extend. λ' c1 is the wavelength of the first reproduced light Lc1 traveling in the hologram element 13. φ2 is the angle at point P between the second reproduced light Lc2 and the direction in which the interference fringes 30 extend. λ' c2 is the wavelength of the second reproduced light Lc2 traveling in the hologram element 13. m1 and m2 are arbitrary natural numbers.

Equation

[0117] In the above formula (12), when any natural numbers m1 and m2 are the same, the wavelength λ' in the hologram element 13 of the second reproduction light Lc2 c2 and the wavelength λ' in the hologram element 13 of the first reproduction light Lc1 c1 have the relationship shown in the following formula (13). In formula (13), φ1 is the angle at point O between the first reproduction light Lc1 and the direction in which the interference fringes 30 extend. φ2 is the angle at point P between the second reproduction light Lc2 and the direction in which the interference fringes 30 extend.

Equation

[0118] When the wavelength λ' in the hologram element 13 of the second reproduction light Lc2 c2 is shorter than the wavelength λ' in the hologram element 13 of the first reproduction light Lc1 c1 in the above formula (13), the incident angle φ2 of the second reproduction light Lc2 on the interference fringes 30 is smaller than the incident angle φ1 of the first reproduction light Lc1 on the interference fringes 30.

[0119] Since the angle φ2 is smaller than the angle φ1, from the above formula (11), the angle θ' between the second reproduction light Lc2 refracted at point A and the first direction D1 c2 is larger than the angle θ' between the first reproduction light Lc1 refracted at point A and the first direction D1 c1 Also, from formulas (5) and (7), the ratio of the sine of the angle θ d1 to the sine of the angle θ' d1 is the same as the ratio of the sine of the angle θ d2 to the sine of the angle θ' d2 The sine of the angle θ d2 is larger than the sine of the angle θ d1 Therefore, when the wavelength λ c of the reproduction light Lc is shorter than the wavelength λ r of the light used for manufacturing the hologram element 13, as shown in FIG. 5, the incident angle θ c2 of the second reproduction light Lc2 c1becomes larger. In other words, the incident angle θ of the second reproduction light Lc2 c2 is larger than the incident angle θ of the reference light Lr at the time of manufacturing the hologram element 13 r . As a result, the hologram element 13 shown in FIGS. 3 and 5 can reproduce the image IM with the second reproduction light Lc2 incident at an incident angle θ r larger than θ c2 .

[0120] The hologram element 13 that enables the reproduction of the image IM by the second reproduction light Lc2 can be manufactured without increasing the incident angle of the light irradiated as the reference light to the hologram photosensitive material. In manufacturing the hologram element 13 shown in FIGS. 3 and 5, an increase in the exposure time to the above-described hologram photosensitive material can be suppressed. Therefore, the illustrated hologram element 13 can suppress a deterioration in production efficiency and an increase in production cost.

[0121] Also, as a conventional technique, a small display device using a light guide plate and an illumination holographic optical element has been devised. However, in addition to image reproduction, a hologram element must be manufactured for illumination, increasing the cost. In this method, by omitting the manufacture of the hologram element for illumination, an increase in production cost can be suppressed as compared with a small display device using a light guide plate and an illumination holographic optical element.

[0122] Also, in the display device 10 shown in FIGS. 1 to 3, the light source 11 can cause diffraction in the hologram element 13 by applying reproduction light Lc having an incident angle θ r larger than θ c to the incident surface 13s. In the illustrated display device 10, in reproducing the image IM, the light source 11 can emit the light source light Ls from a position relatively close to the hologram element 13 in the first direction D1. Therefore, the amount of protrusion in the first direction D1 of the light source 11 and the shaping optical system 12 of the display device 10 can be reduced, and an increase in the size of the display device 10 can also be suppressed. As a result of suppressing the increase in the size of the display device 10, the applicable range of the display device 10 can be expanded.

[0123] The wavelength λ of the light used to fabricate the hologram element 13 r is estimated by the following method using a display device 10 including the fabricated hologram element 13. White light is irradiated onto the incident surface of the hologram element. The spectral transmittance of the hologram element is measured while changing the angle of incidence on the incident surface between 0° and 90°. At each incident angle, the spectral transmittance of wavelengths in the range of 300 nm to 780 nm is measured at 0.5 nm intervals. From the measurement results of the spectral transmittance at each incident angle, the spectral valley where the transmittance drops compared to the preceding and following wavelengths and the wavelength at this spectral valley are identified. In all measurement results, the wavelength at the spectral valley where the difference in transmittance with the preceding and following wavelengths is the largest is determined as the wavelength λ of the light used to fabricate the hologram element. c The spectral transmittance is measured using an integrating sphere.

[0124] In the illustrated input device 1, a first electrode 51 of the sensor 5 is disposed at a position overlapping with a reproduced image IM in a first direction D1. By observing the image IM, a viewer of the image IM may bring an external conductor such as a finger close to the first electrode 51. When the external conductor approaches, the electric field between the first electrode 51 and the second electrode 52 is blocked by the external conductor. This causes a change in the capacitance between the first electrode 51 and the second electrode 52. The sensor 5 detects the change in the capacitance between the first electrode 51 and the second electrode 52 as the approach of the external conductor. The detection result by the sensor 5 may be transmitted to an external control device (not shown).

[0125] 2 and 3, the light source light Ls can be reflected at the incident surface 13s of the hologram element 13. The light source light Ls reflected at the incident surface 13s has a wavelength λ of the reproduced light Lc, for example. c and has the same incident angle θ as the reconstructed light Lc. c When the light source light Ls includes such light, the display device 10 shown in the figure has an incident angle θ c is the incident angle θ of the reference light Lc rBy becoming larger than, the reflection angle of the light source light Ls reflected on the incident surface 13s increases. Thereby, the traveling direction of the light reflected on the incident surface 13s can be separated from the traveling direction of the diffracted light Ld in the first direction D1. Therefore, in the illustrated display device 10, it is possible to suppress the light source light Ls reflected on the incident surface 13s and the diffracted light Ld from being displayed overlappingly. Note that the reflection angle of the light source light Ls is the angle between the optical axis of the light source light Ls and the direction orthogonal to the reflection surface of the hologram element 13 (the incident surface 13s in FIGS. 1 to 3).

[0126] In particular, the display device 10 shown in FIGS. 2 and 3 includes a light shielding plate 14 that can absorb the light source light Ls reflected on the incident surface 13s of the hologram element 13. By the light shielding plate 14 absorbing the light source light Ls reflected on the incident surface 13s, it is possible to suppress light other than the diffracted light Ld for reproducing the image IM from being unintentionally displayed. Therefore, it is possible to effectively suppress the deterioration of the image quality of the image IM reproduced by the display device 10.

[0127] The display device 10 shown in FIGS. 1 to 3 includes a plate-like member 20 that overlaps the light source 11, the shaping optical system 12, and the hologram element 13 from the first direction D1. The plate-like member 20 has a first region 201 that overlaps the light source 11 and the shaping optical system 12, and a second region 202 that overlaps the hologram element 13. The visible light transmittance of the plate-like member 20 in the first region 201 is lower than the visible light transmittance of the plate-like member 20 in the second region 202.

[0128] In the illustrated display device 10, the plate-like member 20 forms the outer surface of the display device 10. The plate-like member 20 can cover the light source 11, the shaping optical system 12, and the hologram element 13, which are arranged at positions where the image IM can be reproduced, from a plane orthogonal to the first direction D1. The plate-like member 20 can conceal the light source 11 and the shaping optical system 12 in the second region 202 with a relatively low visible light transmittance. By these means, when the display device 10 is observed from the outer surface, it can be suppressed that the display device 10 is observed as having a portion protruding in the first direction D1. Therefore, according to the illustrated display device 10, deterioration of the design property in the application target of the display device 10 can be suppressed.

[0129] The visible light transmittance of the plate-like member 20 in the first region 201 may be 50% or less, or may be 1% or less. According to such a display device 10, the plate-like member 20 can effectively suppress the light source 11 and the shaping optical system 12 from being observed from the outer surface of the display device 10. By concealing the light source 11 and the shaping optical system 12 arranged at positions where the image IM can be reproduced, it can be suppressed that the display device 10 is observed as including a portion protruding in the first direction D1.

[0130] In the illustrated display device 10, the first direction D1 is orthogonal to the vertical direction. The first direction D1 may be inclined by 45° or more with respect to the vertical direction. The shaping optical system 12 is located below the hologram element 13. In this display device 10, the image IM is reproduced by the light source light Ls emitted from below. In other words, it can be suppressed that the image IM is unintentionally reproduced by the external light irradiated on the hologram element 13 from above.

[0131] Incidentally, when lights having different wavelengths are diffracted by a hologram element respectively, the diffracted lights travel in different directions. As an example of this, FIG. 5 shows a first reproduction light Lc1 and a second reproduction light Lc2 having different wavelengths. As described above, the first reproduction light Lc1 and the second reproduction light Lc2 satisfy the Bragg condition respectively. In FIG. 5, a first diffracted light Ld1 which is the diffracted light of the first reproduction light Lc1 is emitted from a point B on the incident surface 13s of the hologram element 13. In FIG. 5, a second diffracted light Ld2 which is the diffracted light of the second reproduction light Lc2 is emitted from a point C on the incident surface 13s of the hologram element 13. The first diffracted light Ld1 is inclined by an angle θ d1 only. The second diffracted light Ld2 is inclined by an angle θ d2 only. Due to the difference in the inclination angles with respect to the first direction D1, the first diffracted light Ld1 and the second diffracted light Ld2 travel in different directions from the point P as shown in FIG. 5.

[0132] The plurality of diffracted lights traveling in different directions reproduce images at different positions. As a result, in the display device, a problem that the image quality deteriorates may occur. As an example, when a plurality of diffracted lights traveling in different directions reproduce an image, in the display device, a problem may occur that the outline of the image is blurred and displayed. As another example, when a plurality of diffracted lights traveling in different directions reproduce an image, in the display device, a problem may occur that a plurality of images having different colors are displayed at different positions.

[0133] Moreover, the above-described deviation between the direction in which the first diffracted light Ld1 travels and the direction in which the second diffracted light Ld2 travels increases as each diffracted light moves away from the incident surface 13s in the first direction D1. The arrows AR1 and AR2 in FIG. 5 indicate such an increase in the deviation. In FIG. 5, as the distance from the incident surface 13s in the first direction D1 increases, the distance in the second direction D2 between the first diffracted light Ld1 and the second diffracted light Ld2 increases. In the display device, as the image IM is displayed at a position farther from the hologram element 13 in the first direction D1, there may occur a problem that the blurring of the contour of the image IM deteriorates. In the display device, as the image IM is displayed at a position farther from the hologram element 13 in the first direction D1, there may occur a problem that a plurality of images having different colors are displayed at positions separated from each other.

[0134] The above-described problems may occur when the light source light Ls includes a plurality of reproduced lights having different wavelengths from each other, or when the light source light Ls has a wavelength width. Specifically, the above-described problems may occur when the light source 11 includes a light-emitting diode. From the viewpoint of suppressing the deterioration of the image quality, the light source light Ls may be monochromatic light. By the monochromatic light emitted from the light source 11 satisfying the above-described Bragg conditions, it is possible to suppress the diffraction of the lights of a plurality of wavelengths included in the light source light Ls in the hologram element 13. Thereby, it is possible to suppress the occurrence of variations in the direction in which the diffracted light Ld travels, and to suppress the deterioration of the image quality described above.

[0135] Moreover, from the viewpoint of suppressing the deterioration of the image quality, in the display device 10, an upper limit value may be set for the distance between the hologram element 13 and the image IM in the first direction D1. The distance between the hologram element 13 and the image IM in the first direction D1 may be 50 mm or less, or may be 30 mm or less. Thereby, even when the light source light Ls includes a plurality of reproduced lights or when the light source light Ls has a wavelength width, it is possible to suppress the expansion of the deviation occurring at the position where the image IM is reproduced. Therefore, it is possible to reduce the manufacturing cost of the display device 10 and to suppress the deterioration of the image quality of the image IM.

[0136] In the embodiment described above, the display device 10 includes a light source 11, a shaping optical system 12 that shapes the light source light Ls emitted by the light source 11, and a hologram element 13 that reproduces an image IM with the light source light Ls shaped by the shaping optical system 12. The hologram element 13 has an incident surface 13s on which the light source light Ls shaped by the shaping optical system 12 is incident. The image IM is reproduced at a position separated from the hologram element 13 in a first direction D1 orthogonal to the incident surface 13s. The light source light Ls includes light having a wavelength λ r shorter than the wavelength λ c used for manufacturing the hologram element 13.

[0137] According to this embodiment, the display device 10 can reproduce the image IM by applying a reproduction light Lc having an incident angle θ r larger than the incident angle θ c to the incident surface 13s of the hologram element 13. In manufacturing such a hologram element 13, it is possible to suppress a deterioration in production efficiency and an increase in production cost due to an increase in the exposure time of the hologram photosensitive material. Further, according to such a display device 10, the light source 11 can be disposed at a position relatively close to the hologram element 13 in the first direction D1. Therefore, the display device 10 according to this embodiment can suppress an increase in size and production cost.

[0138] Although an embodiment has been described with reference to specific examples, the above-described specific examples do not limit the embodiment. The above-described embodiment can be implemented with various other specific examples, and various omissions, replacements, changes, additions, etc. can be made without departing from the gist thereof.

[0139] Hereinafter, an example of a modification will be described with reference to the drawings. In the following description and the drawings used in the following description, for parts that can be configured in the same manner as the above-described specific examples, the same reference numerals as those used for the corresponding parts in the above-described specific examples are used, and redundant descriptions are omitted.

[0140] The above-described display device 10 included a light-shielding plate 14 capable of absorbing the light source light Ls reflected at the incident surface 13s of the hologram element 13. The light-shielding plate 14 faced a second direction D2 orthogonal to the first direction D1. As shown in FIG. 7, the light-shielding plate 14 may be disposed in a state inclined with respect to the first direction D1. In the illustrated display device 10, the distance in the first direction D1 between the inclined light-shielding plate 14 and the hologram element 13 decreases as it moves away from the light source 11 or the shaping optical system 12 in the second direction D2. According to the display device 10 shown in FIG. 8, it is possible to suppress the light source light Ls reflected at the incident surface 13s and reflected at the light-shielding plate 14 from advancing to the first side in the first direction D1. Therefore, in the display device 10 shown in FIG. 7, it is possible to suppress the light source light Ls reflected at the incident surface 13s and the diffracted light Ld from being displayed overlapping each other.

[0141] The above-described display device 10 included, as a support portion 15, a housing 16 that houses the light source 11, the shaping optical system 12, the hologram element 13, and the light-shielding plate 14. Not limited thereto, the support portion 15 may include a display 19 that displays an image, as shown in FIG. 7. The display 19 may display an image that serves as a background for the image IM. The illustrated support portion 15 includes a display 19 and a frame member 18 positioned between the display 19 and a plate-like member 20 in the first direction D1. The frame member 18 surrounds the periphery of the display 19. The frame member 18 includes a portion extending in the second direction D2 and a portion extending in the third direction D3. In the illustrated display device 10, the light source 11, the shaping optical system 12, and the light-shielding plate 14 are attached to the frame member 18. The hologram element 13 is overlaid on the display 19.

[0142] The display 19 shown in FIG. 7 has a longitudinal direction in the second direction D2 and a width direction in the third direction D3. The illustrated display 19 emits light from a light-emitting surface 19a. An image is formed by the light emitted from the light-emitting surface 19a. The display 19 may include one or more of a liquid crystal display, a plasma display, and an organic EL display.

[0143] In the display device 10 shown in FIG. 7, the hologram element 13 has visible light transmissivity. The hologram element 13 may have visible light transmissivity to such an extent that it can transmit the light emitted from the light emitting surface 19a of the display 19. The hologram element 13 may be transparent.

[0144] In addition to the image IM, the display device 10 may display a design. As a configuration for the display device 10 to display a design, as shown in FIGS. 7 and 8, the plate-like member 20 may include a base portion 21 and a decorative portion 23 overlapped with the base portion 21 in the first direction D1. In the illustrated display device 10, the plate-like member 20 can display a design by the decorative portion 23.

[0145] As shown in FIGS. 7 and 8, the decorative portion 23 may be a decorative sheet 70. In the illustrated plate-like member 20, as the decorative portion 23, the decorative sheet 70 is provided in both the first region 201 and the second region 202. By providing the decorative sheet 70 in both the first region 201 and the second region 202 of the plate-like member 20, the display device 10, or the input device 1 including the display device 10, can be harmonized with the surrounding environment. The decorative sheet 70 may be joined to the base portion 21. The decorative sheet 70 may be referred to as a decorative plate.

[0146] The decorative sheet 70 may display a design that serves as the background of the image IM. In the display device 10 shown in FIGS. 7 and 8, the decorative sheet 70, which is the decorative portion 23, displays a design that serves as the background of the image IM when the display 19 stops displaying an image. The decorative sheet 70 may display a wood grain pattern, a marble pattern, a geometric pattern, etc. as the design that serves as the background of the image IM. As other designs, the decorative sheet 70 may display one or more of pictures such as figures, patterns, designs, colors, paintings, photographs, characters, marks, pictograms, characters, and numbers.

[0147] Referring mainly to FIG. 8, the details of the decorative sheet 70 will be described. The decorative sheet 70 shown in FIG. 8 has a transmissive portion 70a having visible light transmissivity and a light shielding portion 70b having visible light light-shielding property. The illustrated transmissive portion 70a has visible light transmissivity to such an extent that it can transmit diffracted light diffracted by the hologram element 13 and light emitted from the light emitting surface 19a of the display 19. In the illustrated decorative sheet 70, the transmissive portion 70a is located in the second region 202. The transmissive portion 70a is not located in the first region 201. By arranging the transmissive portion 70a only in the second region 202, the visible light transmittance in the first region 201 becomes smaller than the visible light transmittance in the second region 202. The light shielding portion 70b suppresses the emission of the light source light Ls in the first region 201.

[0148] As shown in FIG. 8, the decorative sheet 70 includes a bonding layer 71 and a base material 72 in this order in the transmissive portion 70a. As shown in FIG. 8, the decorative sheet 70 includes a bonding layer 71, a base material 72, a light shielding layer 73, a design layer 74, and a surface layer 75 in this order in the light shielding portion 70b in a direction away from the base portion 21 in the first direction D1. The illustrated decorative sheet 70 includes a recess 70r that penetrates the surface layer 75, the design layer 74, and the light shielding layer 73. The transmissive portion 70a of the illustrated decorative sheet 70 is formed by the recess 70r. The recess 70r may be formed by various methods such as laser etching and sandblasting.

[0149] The bonding layer 71 improves the adhesion between the decorative sheet 70 and the base portion 21. The bonding layer 71 may contain an adhesive. The bonding layer 71 may contain an adhesive agent.

[0150] The base material 72 supports layers other than the base material 72 of the decorative sheet 70. The base material 72 may be made of resin.

[0151] The light shielding layer 73 has visible light light-shielding property. The light shielding layer 73 may contain a binder resin and light absorbing particles dispersed in the binder resin. The light absorbing particles may contain black pigments such as carbon black and titanium black.

[0152] The design layer 74 forms a design. The design displayed by the design layer 74 may include one or more of patterns such as figures, patterns, designs, colors, pictures, photographs, characters, marks, pictograms, and pictorials such as letters and numbers. The design layer 74 may include a binder resin portion and a coloring material held by the binder resin portion. The coloring material may be a dye, a pigment, or a combination of a dye and a pigment.

[0153] The surface layer 75 may have various functions. As an example, the surface layer 75 may be an antireflection layer. The antireflection layer may suppress the reflection of external light on the outer surface of the display device 10 or the input device 1. The refractive index of the antireflection layer may be lower than the refractive index of other layers of the decorative sheet 70 adjacent in the first direction D1. The antireflection layer may include particles for adjusting the refractive index, such as hollow silica, and a fluorine additive.

[0154] Note that, as a configuration for displaying a design, the display device 10 may include a decorative member 60 stacked on the plate-like member 20 instead of the decorative portion 23 included in the plate-like member 20, as shown in FIG. 10. As shown in FIG. 10, the display device 10 may display an image IM reproduced by the hologram element 13 and a design displayed by the decorative member 60.

[0155] The decorative member 60 may be the above-described decorative sheet 70, as shown in FIG. 10. The decorative sheet 70 shown in FIG. 10 displays the character string "PUSH". The decorative member 60 may be in a form other than the decorative sheet 70.

[0156] As shown in FIG. 9, the hologram element 13 may be held in a state inclined toward the shaping optical system 12. In the illustrated hologram element 13, the first direction D1 is at an angle θ with respect to the direction NP1 orthogonal to the first surface 20a of the plate-like member 20. hIt is only inclined. The support part 15 includes an inclined support part 17 that supports the hologram element 13 in an inclined state. The inclined support part 17 is disposed on the bottom plate part 161 of the housing 16. According to the display device 10 shown in FIG. 9, the length of the hologram element 13 in the direction orthogonal to the direction NP1 orthogonal to the first surface 20a of the plate-like member 20 can be reduced. By reducing the length of the hologram element 13 in the direction NP1 orthogonal to the first surface 20a of the plate-like member 20, in the illustrated display device 10, the housing 16 can be miniaturized. By inclining the hologram element, the incident angle θ c to the incident surface 13s can be adjusted without inclining the shaping optical system 12. In particular, when the hologram element 13 has dimensions larger than those of the shaping optical system 12, by inclining the hologram element 13, the incident angle θ c can be easily adjusted.

[0157] In the above-described display device 10, the image IM was reproduced at a position away from the plate-like member 20 in the first direction D1. The plate-like member 20 was located between the hologram element 13 and the image IM in the first direction D1. The image IM may include an intersection portion IMA that intersects the plate-like member 20 as shown in FIGS. 9 and 10. In the illustrated intersection portion IMA, the position of the image IM in the first direction D1 is the same as the position of the plate-like member 20 in the first direction D1. The images IM shown in FIGS. 9 and 10 include a portion located farther from the hologram element 13 than the plate-like member 20, an intersection portion IMA that intersects the plate-like member 20, and a portion located closer to the hologram element 13 than the plate-like member 20.

[0158] An observer observing the display device 10 shown in FIGS. 9 and 10 observes the image IM including the plate-like member 20 and the intersection portion IMA. The observer can easily recognize the portion located farther from the hologram element 13 than the plate-like member 20 as the portion where the image IM protrudes from the outer surface of the display device 10. Therefore, the illustrated display device 10 can prompt the image IM to protrude and be observed from the outer surface of the display device 10.

[0159] In the display device 10 shown in FIG. 10, the image IM and the decorative member 60 are separated from each other in the second direction D2. The image IM does not include a portion that intersects the decorative member 60. Different from the illustrated display device 10, the image IM may include a portion that intersects the decorative member 60.

[0160] In the display device 10 shown in FIG. 2, the image IM was two-dimensional. The two-dimensional image IM spread on a plane perpendicular to the first direction D1. As shown in FIG. 9, the two-dimensional image IM may spread on a plane inclined with respect to the plane orthogonal to the first direction D1.

[0161] As shown in FIG. 10, the display device 10 may display a three-dimensional image IM. The image IM shown in FIG. 10 has a certain length in the first direction D1, the second direction D2, and the third direction D3. The image IM may include an intersection portion IMA that intersects the plate-like member 20 as shown in FIG. 10. The image IM shown in FIG. 10 includes a portion that displays a cylinder having an axial direction in the first direction D1 and a portion that displays an arrow.

[0162] In the above-described display device 10, the visible light transmittance of the plate-like member 20 in the first region 201 was lower than the visible light transmittance of the plate-like member 20 in the second region 202. In the first region 201, the observation of the light source light Ls emitted from the light source 11 was suppressed. Not limited to this, as shown in FIG. 10, in the first region 201, the light source light Ls may be observable. In the illustrated display device 10, the plate-like member 20 has an opening 20X in the first region 201. The illustrated plate-like member 20 does not include a light-shielding portion 22 in the opening 20X. The plate-like member 20 may not include the base portion 21 in the opening 20X. In the illustrated plate-like member 20, the character string "PUSH" is formed in the opening 20X. In the illustrated display device 10, when the light source 11 emits the light source light Ls, the character string "PUSH" can be displayed by the light source light Ls.

[0163] The above-described display device 10 included one hologram element 13. However, it is not limited to this, and the display device 10 may include a plurality of hologram elements 13. The plurality of hologram elements 13 may be arranged side by side in a direction non-parallel to the first direction D1. Each of the plurality of hologram elements 13 may reproduce the image IM with reproduction light Lc having different wavelengths from each other. Each of the plurality of hologram elements 13 may reproduce the image IM with reproduction light Lc from different directions from each other.

[0164] The above-described display device 10 included one light source 11. The display device 10 may include a plurality of light sources 11. The plurality of light sources 11 may be arranged at different positions from each other. In the display device 10, the image IM may be displayed by lighting some of the plurality of light sources 11. In the display device 10, the display position of the image IM may be switched by switching the light source 11 to be lit. By switching the display position of the image IM, the display device 10 may display the image IM as a moving image.

Explanation of Reference Numerals

[0165] 1: Input device, 5: Sensor, 10: Display device, 11: Light source, 12: Shaping optical system, 13: Hologram element, 14: Light shielding plate, 15: Support portion, 16: Housing, 19: Display, 20: Plate-like member, 201: First region, 202: Second region, 50: Lens, 50s: Optical axis, Ls: Light source light, IM: Image

Claims

1. A light source, a shaping optical system that shapes the light from the light source, and a hologram element that reproduces an image with the light from the light source shaped by the shaping optical system, wherein the hologram element has an incident surface on which the light from the light source shaped by the shaping optical system is incident, the image is reproduced at a position separated from the hologram element in a first direction orthogonal to the incident surface, and the light from the light source includes light having a wavelength shorter than the wavelength of the light used for manufacturing the hologram element, a display device.

2. The first direction is inclined by 45° or more or orthogonal to the vertical direction, and the shaping optical system is located below the hologram element, the display device according to Claim 1.

3. The light from the light source is monochromatic light, the display device according to Claim 1.

4. The shaping optical system includes a lens, and the optical axis of the lens is inclined toward the hologram element with respect to the first direction, the display device according to Claim 1.

5. A plate-like member that overlaps the light source, the shaping optical system, and the hologram element, the plate-like member has a first region that overlaps the light source and the shaping optical system and a second region that overlaps the hologram element, and the visible light transmittance of the plate-like member in the first region is lower than the visible light transmittance of the plate-like member in the second region, the display device according to Claim 1.

6. The visible light transmittance of the plate-like member in the first region is 50% or less, the display device according to Claim 5.

7. The plate-like member is located between the hologram element and the image in the first direction, the display device according to Claim 5.

8. The image includes an intersection portion that intersects the plate-like member, the display device according to Claim 5.

9. The distance between the hologram element and the plate-like member in the first direction is 10 mm or less, the display device according to Claim 5.

10. A support portion that supports the light source, the shaping optical system, and the hologram element, and the plate-like member is disposed facing the support portion in the first direction, the display device according to Claim 5.

11. The support portion is a housing that opens in the first direction, and the plate-like member covers the opening, the display device according to Claim 10.

12. The support portion includes a display, the display device according to Claim 10.

13. The plate-like member has a first surface and a second surface opposite to the first surface, The display device according to claim 5, wherein the first direction is inclined with respect to either a direction orthogonal to the first surface or a direction orthogonal to the second surface.

14. The display device according to claim 1, further comprising a light shielding plate capable of absorbing the light source light reflected on the incident surface of the hologram element.

15. An input device, comprising: the display device according to any one of claims 1 to 14; and a sensor configured to detect an object approaching or approaching the image.

Images