projector

Abstract

To provide a projector that enables a reduction in size and thickness as a whole while avoiding deterioration in an image.SOLUTION: The projector includes: a plurality of display elements 11r, 11g, and 11b for emitting light having mutually different wavelength bands; a plurality of diffraction elements 21r, 21g, and 21b (first diffraction element DE1) that diffracts each color light GLr, GLg, and GLb emitted from the plurality of display elements 11r, 11g, and 11b; a second diffraction element DE2 that is a synthetic diffraction element for synthesizing each color light GLr, GLg, and GLb from the plurality of diffraction elements 21r, 21g, and 21b; a projection optical system 30 that projects image light GL as synthetic light generated by the second diffraction element DE2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a small projector that uses a hologram. [Background technology]

[0002] An optical unit that can be applied to a projection display device is known, which uses a dichroic prism with two intersecting dichroic mirrors to combine light from three panels with light-emitting elements (Patent Document 1).

[0003] Furthermore, a multicolor projection device that utilizes diffraction by a hologram is known (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-174515 [Patent Document 2] Japanese Patent Application Publication No. 3-198491 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when attempting to miniaturize a device while using a dichroic prism as exemplified in Patent Document 1, the dichroic prism itself must be made smaller, which raises concerns about the impact of image quality degradation, for example, at the center of the image where the dichroic mirrors intersect. Patent Document 2 discloses an embodiment that does not use a dichroic prism, but such a configuration does not necessarily enable high-resolution image formation while miniaturizing the entire device to the extent that it can be easily carried or even incorporated into other devices. At the very least, Patent Document 2 does not provide sufficient disclosure that would enable such miniaturization. [Means for solving the problem]

[0006] A projector according to one aspect of the present invention includes a plurality of display elements that emit light of different wavelength bands, a plurality of diffraction elements that diffract the colored light emitted from the plurality of display elements, a combining diffraction element that combines the colored light from the plurality of diffraction elements, and a projection optical system that projects the combined light generated by the combining diffraction element. The plurality of diffraction elements and the composite diffraction element are reflection holograms, and the composite diffraction element is configured so that each color light is emitted from the composite diffraction element at the same angle as the angle of incidence when the color light is incident on the plurality of diffraction elements. . [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual side cross-sectional view for explaining a projector according to a first embodiment. [Figure 2] FIG. 1 is a conceptual plan view showing how a projector projects onto a screen. [Figure 3] FIG. 1 is a conceptual perspective view showing an example of the appearance of a projector. [Figure 4] FIG. 2 is a conceptual front view showing an example of an arrangement of display elements. [Figure 5] FIG. 10 is a conceptual cross-sectional side view showing a modified example of a composite diffraction element. [Figure 6] FIG. 10 is a conceptual side cross-sectional view for explaining a projector according to a second embodiment. [Figure 7] FIG. 1 is a conceptual plan view showing how a projector projects onto a screen. [Figure 8] FIG. 10 is a conceptual side cross-sectional view illustrating a projector according to a modified example. [Figure 9] FIG. 1 is a conceptual side cross-sectional view showing an example of the external shape of a projector. [Figure 10] FIG. 1 is a conceptual diagram showing an example of application of a projector. [Figure 11] FIG. 10 is a conceptual side cross-sectional view illustrating a projector according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] [First embodiment] A projector according to a first embodiment of the invention will be described below with reference to the drawings.

[0009] Fig. 1 is a conceptual side cross-sectional view for explaining a projector 100 of this embodiment. Fig. 2 is a conceptual side cross-sectional view showing how projection onto a screen SC is performed by the projector 100. As shown in Fig. 1, the projector 100 includes a light source unit 10, a light guide device 20, and a projection optical system 30. These units are housed in a housing CS together with various circuits, a power supply, and the like (not shown).

[0010] 1 etc., X, Y, and Z are Cartesian coordinate systems, and the +Z direction indicates the optical axis direction, which indicates the emission direction of image light GL from the light source unit 10. The X direction corresponds to the lateral direction (horizontal direction) of the light source unit 10, and the Y direction corresponds to the longitudinal direction (vertical direction) perpendicular to the lateral direction (horizontal direction).

[0011] The light source unit 10 includes three (plural) display elements 11r, 11g, and 11b that emit light in different wavelength bands, and a support substrate BS that supports them. Each of the display elements 11r, 11g, and 11b is a self-luminous type, typified by, for example, organic electroluminescence (EL), inorganic EL, LED array (micro LED array), organic LED, laser array, quantum dot light-emitting element, etc., and is a display device that forms still or moving images of each color on a two-dimensional display area parallel to the XY plane.

[0012] Of the multiple display elements 11r, 11g, and 11b, the display element 11r, which is the first display element, emits light in the red wavelength band as light in the first wavelength band. The display element 11g, which is the second display element, emits light in the green wavelength band as light in the second wavelength band. The display element 11b, which is the third display element, emits light in the blue wavelength band as light in the third wavelength band. The support substrate BS is a single plate-like member, and its surface is parallel to the XY plane. The support substrate BS is a panel substrate that supports the display elements 11r, 11g, and 11b and is provided with drive circuits for driving them.

[0013] In the example shown, the three display elements 11r, 11g, and 11b are arranged in a row in the vertical direction (Y direction) on the surface of the support substrate BS, i.e., within one plane (XY plane), with display element 11b, the third display element that emits light in the blue wavelength band, i.e., light in the shortest wavelength band, at the center.

[0014] The light guide device 20 includes a first light guide member 21 and a second light guide member 22. The first light guide member 21 includes a first diffraction element DE1, a first glass substrate GS1 that is a single plate-like member and is optically transparent, and multiple collimating lenses COr, COg, and COb. Of these, the first diffraction element DE1 is composed of three (multiple) diffraction elements 21r, 21g, and 21b, and is adhered and fixed to the first glass substrate GS1. The diffraction elements 21r, 21g, and 21b are disposed to face the display elements 11r, 11g, and 11b, respectively, and are transmission-type hologram elements that diffract the color light emitted from the display elements 11r, 11g, and 11b. Here, a volume hologram may be used as the transmission-type hologram element, but other hologram elements may also be used.

[0015] Here, each of the collimating lenses COr, COg, and COb is a collimator that collimates the ray bundles of each color light passing through it, and is provided between the display elements 11r, 11g, and 11b and the diffraction elements 21r, 21g, and 21b, i.e., on the upstream side (-Z side) of the diffraction elements 21r, 21g, and 21b. As a result, each of the color lights from the display elements 11r, 11g, and 11b is incident on the diffraction elements 21r, 21g, and 21b in a collimated state.

[0016] The second light-guiding member 22 includes a second diffraction element DE2 and a light-transmitting second glass substrate GS2 that is a single plate-like member. The second diffraction element DE2 is a combining diffraction element that combines the light from the first diffraction element DE1, i.e., the color lights from the three display elements 11r, 11g, and 11b, and is adhered and fixed to the second glass substrate GS2. The second diffraction element DE2 is a transmission-type hologram element that diffracts and emits the combined light toward the projection optical system 30. Here, a volume hologram may be used as the transmission-type hologram element, but other hologram elements may also be used.

[0017] The projection optical system 30 projects the combined light generated by the second diffraction element DE2, which is a combined diffraction element, as image light GL. That is, the image light GL that has passed through the projection optical system 30 is emitted toward a screen SC and forms an image, as illustrated in FIG.

[0018] The generation and projection of image light GL using the above configuration will be described below along the optical paths of each color light. Here, for the three display elements 11r, 11g, and 11b that generate the component lights that make up image light GL, the light emitted from display element 11r is referred to as red light GLr, the light emitted from display element 11g is referred to as green light GLg, and the light emitted from display element 11b is referred to as blue light GLb.

[0019] First, the red light GLr emitted from the display element 11r is collimated by the collimating lens COr in the first light guiding member 21 and enters the diffraction element 21r. When the red light GLr, which travels in the +Z direction, enters the diffraction element 21r, it is diffracted by the diffraction element 21r and deflected so as to slightly include the −Y direction as a whole, and heads toward the second diffraction element DE2 of the second light guiding member 22.

[0020] Next, the green light GLg emitted from the display element 11g is collimated by the collimating lens COg and enters the diffraction element 21g. When the green light GLg, which had been traveling in the +Z direction, enters the diffraction element 21g, it is diffracted by the diffraction element 21g and deflected so that the overall direction is slightly in the +Y direction, and it heads toward the second diffraction element DE2.

[0021] Finally, the blue light GLb emitted from the display element 11b is collimated by the collimating lens COb and enters the diffraction element 21b. When the blue light GLb, which travels in the +Z direction, enters the diffraction element 21b, it is diffracted by the diffraction element 21b and deflected to converge more toward the center, and then directed toward the second diffraction element DE2.

[0022] As described above, the color lights GLr, GLg, and GLb are deflected by the first diffractive element DE1 so as to be converged onto one second diffractive element DE2.

[0023] The second diffraction element DE2 exhibits different diffraction effects corresponding to the wavelengths and incident angles of the incident color lights GLr, GLg, and GLb, and combines the color lights GLr, GLg, and GLb to form the image light GL. That is, it performs color combination corresponding to the angle of view of the display elements 11r, 11g, and 11b. In other words, the second diffraction element DE2 exhibits different diffraction effects corresponding to the light in each wavelength band from the three display elements 11r, 11g, and 11b, aligning the optical paths of the color lights GLr, GLg, and GLb. As a result, the second diffraction element DE2 functions as a combining diffraction element that combines the color lights GLr, GLg, and GLb.

[0024] The image light GL formed by color synthesis at the second diffraction element DE2 is projected onto a screen SC (see FIG. 2) by the projection optical system 30. That is, the image light GL forms an image on the screen SC. In this way, a color still image or moving image is formed on the screen SC.

[0025] The second diffraction element DE2 may have a single-layer structure using a transmission hologram created by simultaneous exposure of three color lights, for example, red light (R light), green light (G light), and blue light (B light), or a multi-layer structure. The second diffraction element DE2 is a composite diffraction element that combines light by diffracting each color light, and may have a multi-layer structure in which diffraction elements corresponding to each color light are stacked. An example of the multi-layer structure will be described in detail later with reference to FIG. 5.

[0026] As described above, the projector 100 is configured with the first diffraction element DE1 and the second diffraction element DE2, enabling the combination of colored light beams using diffraction. This eliminates the need to consider the degradation of image quality associated with miniaturization, as occurs with dichroic mirrors formed by crossing dichroic mirrors. This allows the overall device to be miniaturized while maintaining high image quality. It also enables the formation of high-brightness images while saving power. Furthermore, the light source unit 10 is a self-luminous display device capable of emitting high-brightness light. In this case, a separate light source and a large power supply unit for supplying power to the light source are not required, allowing the overall projector 100 to be smaller and lighter. Note that, since the corresponding field-of-view components of the colored light beams GLr, GLg, and GLb are ultimately focused at the same point on the screen SC (see FIG. 2), it can also be considered that the second diffraction element DE2 and the projection optical system 30 work together to combine the light beams.

[0027] Furthermore, in this case, by using the first diffraction element DE1 and the second diffraction element DE2, which are plate-shaped and transmissive, the projector 100 can be configured to be linear and very compact. Therefore, for example, as shown in states AR1 and AR2 in FIG. 3, the projector 100 can be configured to be pen-shaped, and image light GL can be emitted from a location corresponding to the pen tip. In the example shown in state AR1, the housing CS that determines the appearance of the projector 100 is cylindrical, and in the example shown in state AR2, the housing CS that determines the appearance of the projector 100 is prismatic.

[0028] An example of the arrangement of the three display elements 11r, 11g, and 11b constituting the light source unit 10 will be described below with reference to FIG. 4. In FIG. 4, state BR1 is a front view showing the example arrangement. As shown in the figure, the three display elements 11r, 11g, and 11b are rectangular panel-type elements that are horizontally elongated (longer in the Y direction than in the X direction) and are arranged in one direction (Y direction) in one plane (XY plane). In this case, when viewed from the front, the light source unit 10 can be configured to be vertically elongated as a whole, with less extension in the X direction (horizontal direction). However, this arrangement is not limited to this. For example, as shown in state BR2 or state BR3, the three display elements 11r, 11g, and 11b may be arranged to form a triangle in one plane (XY plane). That is, one of the three display elements 11r, 11g, and 11b may be disposed on the upper side (+Y side) that is the apex side, and the other two may be disposed on the bottom side (-Y side), or an arrangement upside down may be used. In this case, as shown in state BR2, the light source unit 10 may have a horizontally elongated configuration as a whole, with a large spread in the X direction (horizontal direction) when viewed from the front. Alternatively, as shown in state BR3, the light source unit 10 may have a circular shape or a shape similar thereto (a shape spreading isotropically from the center) when viewed from the front.

[0029] In addition, when a triangular arrangement such as shown in state BR2 is used, the arrangement of the diffraction elements 21r, 21g, and 21b corresponding to the three display elements 11r, 11g, and 11b also becomes a triangular arrangement when viewed from the front, as shown by the dashed lines in the figure, and the second diffraction element DE2 is positioned at or near the center of these when viewed from the front, as shown by the dotted line in the figure.

[0030] In the above, taking into consideration the degree of diffraction effect, the arrangement is such that blue light GLb, which is light in the shortest wavelength band, is emitted from the center side where bending due to diffraction is thought to be the least, but the arrangement is not limited to this and can be in various forms.

[0031] Referring now to FIG. 5, a conceptual side cross-sectional view is shown showing a modified example of the second diffraction element DE2, which is a composite diffraction element.

[0032] Here, as described above, an example of a case where the second diffraction element DE2 has a multilayer structure is shown. In the example shown in state CR1 of FIG. 5, the second diffraction element DE2 has a three-layer structure (three-layer configuration) in which a blue diffraction element 22b, a red diffraction element 22r, and a green diffraction element 22g are stacked in the Z direction. That is, the blue diffraction element 22b diffracts the blue light (B light) GLb component of the three colored light having a predetermined wavelength band that constitutes the image light GL from the light source unit 10, while transmitting the other colored light without any effect. Similarly, the red diffraction element 22r diffracts only the red light (R light) GLr component, and the green diffraction element 22g diffracts only the green light (G light) GLg component. This configuration can further improve the utilization efficiency of each colored light.

[0033] In the example shown in state CR1, the blue, red, and green diffraction elements 22b, 22r, and 22g, respectively, are approximately 20 to 40 μm thick and are attached to optically transparent resin or glass substrates BSb, BSr, and BSg. The thickness of the substrates BSb, BSr, and BSg is approximately 0.3 mm, but thinner structures are also possible. The diffraction elements 21b, 21r, and 21g attached to the substrates BSb, BSr, and BSg are fixed with gaps (gap) DD1 and DD2 of approximately 50 μm between them. These gaps DD1 and DD2 are ensured by attaching spacers SS to the peripheral portions of the diffraction elements 21b, 21r, and 21g that do not exhibit optical effects. Providing these gaps DD1 and DD2 creates an air layer AL between the three layers, preventing unintended total reflection on the substrate BSb. Furthermore, with the thickness as described above, even if the second diffraction element DE2 has a three-layer structure, the entire device can maintain a certain degree of thinness in the Z direction. In this case, the second glass substrate GS2 may be omitted if it has sufficient strength.

[0034] On the other hand, if there is no risk of unintended total reflection as described above, for example, due to the angle of incidence, etc., the second diffraction element DE2 having a three-layer structure may be further miniaturized by using a configuration such as the example shown in state CR2 without providing the spacer SS and the resulting spacings DD1 and DD2.

[0035] In the illustrated second diffraction element DE2, the diffraction elements for blue, red, and green are arranged in this order from the light incident side, but the arrangement order is not limited to this and can be variously modified.

[0036] As described above, the projector 100 of this embodiment includes a plurality of display elements 11r, 11g, and 11b that emit light in different wavelength bands, a plurality of diffraction elements 21r, 21g, and 21b (first diffraction element DE1) that diffract the colored light GLr, GLg, and GLb emitted from the plurality of display elements 11r, 11g, and 11b, a second diffraction element DE2 that is a combining diffraction element that combines the colored light GLr, GLg, and GLb from the plurality of diffraction elements 21r, 21g, and 21b, and a projection optical system 30 that projects image light GL as combined light generated by the second diffraction element DE2. In the projector 100, by using the second diffraction element DE2 to combine the colored light GLr, GLg, and GLb that have passed through the diffraction elements 21r, 21g, and 21b, it is possible to reduce the size of the entire device while maintaining high image quality at the center of the image compared to, for example, a case in which a cross prism is used, and it is also possible to form a high-brightness image while saving power.

[0037] Second Embodiment A projector according to the second embodiment will be described below with reference to Fig. 6 and other figures. Fig. 6 is a conceptual side cross-sectional view for explaining an example of a projector 100 according to this embodiment, and corresponds to the side cross-sectional view shown in Fig. 1. As shown in the figure, this embodiment differs from the first embodiment in that reflective hologram elements are used as the first diffraction element DE1 and the second diffraction element DE2.

[0038] In this embodiment, the light guiding device 20 includes a first diffraction element DE1 composed of a plurality of reflective diffraction elements 21r, 21g, and 21b as the first light guiding member 21, and a second reflective diffraction element DE2 as the second light guiding member 22. That is, in the light guiding device 20, the first diffraction element DE1 and the second diffraction element DE2 are reflective hologram elements, and the first diffraction element DE1 and the second diffraction element DE2 are arranged opposite to each other as shown in the figure. Here, it is considered to use a volume hologram as the reflective hologram element, but other hologram elements may also be used.

[0039] The first diffraction element DE1 serving as the first light guiding member 21 diffracts and reflects the image light GL from the light source unit 10. To explain more specifically along the optical paths of the color lights GLr, GLg, and GLb, first, red light GLr emitted from the display element 11r of the light source unit 10 is incident on the diffraction element 21r, where it is deflected by diffraction at the diffraction element 21r, and directed toward the second diffraction element DE2 serving as the second light guiding member 22. Similarly, green light GLg emitted from the display element 11g is incident on the diffraction element 21g, where it is deflected by diffraction at the diffraction element 21g, and directed toward the second diffraction element DE2, and blue light GLb emitted from the display element 11b is incident on the diffraction element 21b, where it is deflected by diffraction at the diffraction element 21b, and directed toward the second diffraction element DE2. However, in the example shown, the three display elements 11r, 11g, and 11b are arranged in a row in this order from the -Y side, and as they are combined at the second diffraction element DE2, the degree to which the optical path is bent by each diffraction effect is different.

[0040] In the example shown in the figure, the degree of diffraction effect is taken into consideration and the arrangement is such that light of longer wavelength bands is emitted in order from the -Y side where bending due to diffraction is greatest, but the arrangement is not limited to this and various forms are possible.

[0041] The colored light beams GLr, GLg, and GLb collected by the second diffraction element DE2 in the above manner are combined by the second diffraction element DE2. At this time, the second diffraction element DE2, acting as a combining diffraction element, also performs angle compensation for the diffraction angles of the diffraction elements 21r, 21g, and 21b. That is, when the colored light beams GLr, GLg, and GLb exit the second diffraction element DE2, they exit at the same angle as the angle of incidence on the diffraction elements 21r, 21g, and 21b. For example, the image light GL, which is combined with the colored light beams GLr, GLg, and GLb incident on the diffraction elements 21r, 21g, and 21b from the +Z direction, is emitted in the +Z direction. The image light GL that has passed through the second diffraction element DE2 is projected onto the screen SC (see FIG. 7) by the projection optical system 30.

[0042] In the above example, an air layer is formed between the light source section 10, the first diffraction element DE1, and the second diffraction element DE2.

[0043] Here, the first diffraction element DE1 (diffraction elements 21r, 21g, 21b) and the second diffraction element DE2 may be supported by, for example, the first glass substrate GS1 and the second glass substrate GS2 (see FIG. 1), as in the first embodiment, and the three display elements 11r, 11g, 11b constituting the light source unit 10 may be supported by a support substrate BS. However, as shown in FIG. 8, for example, in the light guide device 20, instead of the air layer, a light-transmitting member 23 which is a plate-shaped transparent member may be provided, and the light source unit 10 (display elements 11r, 11g, 11b), the first diffraction element DE1, and the second diffraction element DE2 may be attached to predetermined locations of the light-transmitting member 23, and the color lights GLr, GLg, GLb which are to become the image light GL may be guided inside the light-transmitting member 23.

[0044] In this embodiment, the device can be made thinner by using reflective hologram elements as the first diffraction element DE1 and the second diffraction element DE2. For example, when the projector 100 is housed in a housing such as that shown in FIG. 9, the thickness of the projector 100 can be reduced, particularly for components other than the projection optical system (projection lens) 30. This allows, for example, a configuration in which the projector 100 is incorporated into a thin mobile device MD, such as a smartphone equipped with various devices such as a camera CA, to project images, as shown in state DR1 of FIG. 10. Furthermore, as shown in state DR2 of FIG. 10, the projector 100 can be easily installed in glasses GA worn by a viewer or wearer US, and an image can be projected into real space ahead of the viewer's or wearer's line of sight. Furthermore, by adding a switching mechanism CH that can project an image from the projector 100 onto the eyeglass lenses LG of the glasses GA, the glasses GA can be configured as a head-mounted display. Furthermore, as shown in state DR3 of FIG. 10, the projector 100 can be installed more flexibly relative to the viewer M, making installation easier. The projector 100 can be easily installed on the seat CM of the viewer M or on the ceiling CL, and the viewer M can view the image using the surface of the wall WA as a screen SC. The seat CM can also be the driver's seat of a car. The above-mentioned installation modes are not limited to this embodiment and can be adopted in the first embodiment as long as they are applicable.

[0045] 11, the light source unit 10 may project component light EL of a wavelength that is transmitted through the first diffraction element DE1 onto the screen SC as a component other than the image light GL, and may also include a light-receiving unit RR that receives return light RL from the screen SC. More specifically, one of the three diffraction elements 21r, 21g, and 21b that make up the first diffraction element DE1 (in the illustrated example, the diffraction element 21r) may be designed not to diffract components other than the image light GL (components other than visible light in a specific wavelength band), such as ultraviolet light or infrared light, but to transmit these components. In this case, for example, light of a wavelength band component of infrared light may be emitted from the display element 11r of the light source unit 10 as the component light EL, while the light-receiving unit RR may be configured with a photodetector or the like that can detect components in a wavelength band included in the component light EL. The light-receiving surface of the light-receiving unit RR may be arranged so as to be aligned with the light-emitting surface of the display element 11r. As for the component light EL emitted from the light source unit 10, for example, a method of disposing an infrared light array or the like within the panel of the display element 11r can be considered.

[0046] In this case, the position of the screen SC and even the shape of the projection surface can be sensed by irradiating the component light EL (infrared light) as sensing light forward (in the +Z direction) of the projector 100. In the example shown in the figure, an optical element OL is provided for collecting the return light RL, but various types of optical element OL can be used, such as a lens or a diffraction element.

[0047] In this embodiment, the second diffraction element DE2 combines the color lights GLr, GLg, and GLb that have passed through the diffraction elements 21r, 21g, and 21b, thereby enabling the overall device to be miniaturized while maintaining high image quality. Furthermore, it is possible to form a high-brightness image while saving power. In particular, this embodiment enables the overall device to be made thinner. For example, this is particularly effective for a portable device MD equipped with the projector 100 of this embodiment, as illustrated in the state CR1 of FIG. 10, enabling the high-quality projection image of the portable device MD.

[0048] [Variations and Others] The present invention has been described above in accordance with the embodiments, but the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0049] In the projector 100 of each of the above embodiments, the self-luminous light source unit 10 includes an organic EL element, a micro LED array, or the like, but it is also possible to apply the present invention to a light source unit that uses a laser light source, etc. instead.

[0050] Furthermore, when configuring the light source unit 10 using organic EL elements, a micro LED array, or the like, the direction of the emitted image light GL may be adjusted using a micro lens array, etc. Furthermore, if sufficient collimation is possible in this way, it is also possible to consider a configuration in which the collimating lenses COr, COg, and COb in FIG.

[0051] Furthermore, if the light source has a predetermined wavelength bandwidth for each color of light, and color separation may occur when the first diffraction element DE1 diffracts the light, the second diffraction element DE2 may be configured to compensate for this.

[0052] Furthermore, the projector 100 of each of the above-described embodiments can also be used to configure a head-up display.

[0053] In a specific embodiment, the projector includes a plurality of display elements that emit light in different wavelength bands, a plurality of diffraction elements that diffract each color light emitted from the plurality of display elements, a composite diffraction element that combines each color light from the plurality of diffraction elements, and a projection optical system that projects the combined light generated by the composite diffraction element.

[0054] In the above projector, by using a composite diffraction element to combine each color light that has passed through multiple diffraction elements, it is possible to make the entire device smaller while maintaining high image quality at the center of the image compared to, for example, using a cross prism, and it is also possible to form high-brightness images while saving power.

[0055] In a specific aspect, the plurality of display elements are configured by a first display element that emits light of a first wavelength band, a second display element that emits light of a second wavelength band, and a third display element that emits light of a third wavelength band, and the combining diffraction element performs different diffraction actions corresponding to the light of each wavelength band from the plurality of display elements to align the optical paths of the respective color lights. In this case, the respective color lights as the light emitted from the three display elements as the plurality of display elements can be combined by the diffraction action.

[0056] In a specific aspect, the plurality of display elements are three panel-type elements arranged in one direction on one surface, and in this case, the planar range in which the display elements are arranged can be elongated with less expansion in directions other than the one direction.

[0057] In a specific aspect, the plurality of display elements are three panel-type elements arranged in a triangular shape on one surface, and in this case, the planar range in which the display elements are arranged can be configured to have an isotropic spread.

[0058] In a specific aspect, the plurality of diffraction elements and the composite diffraction element are transmission holograms, which allows for miniaturization of the device without causing degradation in image quality, as occurs when, for example, a dichroic prism is used.

[0059] In a specific aspect, a plurality of collimating lenses are provided between the plurality of display elements and the plurality of diffraction elements to collimate the light passing therethrough, thereby ensuring the desired diffraction effect.

[0060] In a specific aspect, the plurality of diffraction elements and the composite diffraction element are reflective holograms, which allows the device to be made thinner without causing degradation in image quality, as occurs when a dichroic prism is also used.

[0061] In a specific aspect, the composite diffraction element combines colored lights while performing angle compensation for the diffraction angles of the multiple diffraction elements.

[0062] In a specific aspect, the composite diffraction element has a single-layer structure, which allows for a simple configuration and allows for miniaturization of the device.

[0063] In a specific aspect, the composite diffraction element has a multi-layer structure, which allows for, for example, appropriate diffraction for each color of light, thereby enabling highly efficient use of light.

[0064] In a specific aspect, in the multi-layer structure, an air layer is provided between each layer, which can avoid or suppress the occurrence of unintended total reflection inside the composite diffraction element.

[0065] In a specific aspect, the plurality of diffraction elements and the composite diffraction element are configured by volume holograms, in which case the intended diffraction effect can be accurately produced.

[0066] In a specific aspect, the display element includes either an organic EL element or a micro LED array, which can reliably ensure a stable light output while achieving low power consumption with a simple configuration. [Explanation of symbols]

[0067] 10...light source unit, 11b, 11g, 11r...display element, 20...light guide device, 21...first light guide member, 21b, 21r, 21g...diffraction element, 22...second light guide member, 22b...blue diffraction element, 22g...green diffraction element, 22r...red diffraction element, 23...light-transmitting member, 30...projection optical system, 100...projector, AL...air layer, BS...support substrate, BSb, BSr, BSg...substrate, CA...camera, CH...switching mechanism, CL...ceiling, CM...seating portion, C Ob, COg, COr...collimating lens, CS...housing, DD1, DD2...spacing, DE1...first diffraction element, DE2...second diffraction element, EL...component light, GA...glasses, GL...image light, GLb...blue light, GLg...green light, GLr...red light, GS1...first glass substrate, GS2...second glass substrate, LG...glasses lens, M...viewer, MD...mobile device, OL...optical element, RL...return light, RR...light receiving unit, SC...screen, SS...spacer, WA...wall

Claims

1. a plurality of display elements that emit light in different wavelength bands; a plurality of diffraction elements that diffract the color light beams emitted from the plurality of display elements; a combining diffraction element that combines the color lights from the plurality of diffraction elements; a projection optical system that projects the combined light generated by the combined diffraction element, the plurality of diffraction elements and the composite diffraction element are reflection holograms, and the composite diffraction element is configured so that each color light is emitted from the composite diffraction element at the same angle as the incident angle when the color light is incident on the plurality of diffraction elements. projector.

2. the plurality of display elements are configured by a first display element that emits light in a first wavelength band, a second display element that emits light in a second wavelength band, and a third display element that emits light in a third wavelength band; The projector according to claim 1 , wherein the composite diffraction element performs different diffraction actions corresponding to light of each wavelength band from the plurality of display elements, thereby aligning the optical paths of the color lights.

3. The projector according to claim 2 , wherein the plurality of display elements are three panel-type elements arranged in one direction on one surface.

4. The projector according to claim 2 , wherein the plurality of display elements are three panel-type elements arranged in a triangular shape within one plane.

5. 5. The projector according to claim 1, wherein the composite diffraction element has a single-layer structure.

6. 5. The projector according to claim 1, wherein the composite diffraction element has a multi-layer structure.

7. The projector according to claim 6 , wherein the multi-layer structure includes an air layer between each layer.

8. 8. The projector according to claim 1, wherein the plurality of diffraction elements and the composite diffraction element are configured by volume holograms.

9. 9. The projector according to claim 1, wherein the display element includes one of an organic EL element and a micro LED array.

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