Optical device and electronic apparatus

Abstract

The present disclosure relates to an optical device and an electronic apparatus that make it possible to reduce loss due to a cross prism. Provided is an optical device in which a first diffraction grating, corresponding to light in a red wavelength band emitted by a first panel, a second diffraction grating, corresponding to light in a green wavelength band emitted by a second panel, and a third diffraction grating, corresponding to light in a blue wavelength band emitted by a third panel, are disposed at different positions in an incident diffraction grating provided on a light guide plate, and the first diffraction grating is disposed offset in a direction that increases the angle of incidence to a first reflection surface that reflects light in the red wavelength band in the cross prism.

Description

Optical and electronic devices

[0001] The present disclosure relates to an optical device and an electronic device, and more particularly to an optical device and an electronic device that are capable of reducing loss due to a cross prism.

[0002] A technology related to a three-panel liquid crystal projector using three RGB panels has been proposed (see, for example, Patent Document 1). Patent Document 1 discloses a projector having three transmissive liquid crystal panels and a cross prism that combines modulated light of three colors emitted from the three transmissive liquid crystal panels to form a color image.

[0003] Japanese Patent Application Laid-Open No. 2002-303825

[0004] The technology disclosed in Patent Document 1 ensures angular characteristics by transmitting green light as P-polarized light and reflecting red and blue light as S-polarized light, but it did not anticipate use with unpolarized light. Therefore, there was a need for technology to reduce loss due to the cross prism when using it with unpolarized light.

[0005] The present disclosure has been made in view of these circumstances, and aims to reduce the loss caused by the cross prism.

[0006] An optical device according to one aspect of the present disclosure includes: a first panel that emits first light corresponding to a red wavelength band; a second panel that emits second light corresponding to a green wavelength band; a third panel that emits third light corresponding to a blue wavelength band; a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and combines optical paths of the first light, the second light, and the third light; a projection lens that projects the light whose optical paths have been combined by the cross prism as image light; and a light guide plate onto which the image light projected from the projection lens is incident, propagates through its interior, and is emitted to the outside. an incident diffraction grating that diffracts the image light that is incident on and enters the light guide plate and causes the image light to propagate inside the light guide plate, and an exit diffraction grating that diffracts the image light that has propagated inside the light guide plate and causes the image light to exit the light guide plate, wherein the incident diffraction grating is composed of a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, and the first diffraction grating, the second diffraction grating, and the third diffraction grating are each arranged at different positions, and the first diffraction grating is arranged so as to be shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism increases.

[0007] An electronic device according to one aspect of the present disclosure includes a first panel that emits first light corresponding to a red wavelength band, a second panel that emits second light corresponding to a green wavelength band, a third panel that emits third light corresponding to a blue wavelength band, a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and combines optical paths of the first light, the second light, and the third light, a projection lens that projects the light whose optical paths have been combined by the cross prism as image light, and a light guide plate onto which the image light projected from the projection lens is incident, propagates inside, and is output to the outside. an incident diffraction grating that diffracts the image light incident on the light guide plate and causes the image light to propagate inside the light guide plate, and an exit diffraction grating that diffracts the image light that has propagated inside the light guide plate and causes the image light to exit the light guide plate, wherein the incident diffraction grating is composed of a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, and the first diffraction grating, the second diffraction grating, and the third diffraction grating are each arranged at different positions, and the first diffraction grating is arranged shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism increases.

[0008] In an optical device and electronic device according to one aspect of the present disclosure, an incident diffraction grating provided on a light guide plate includes a first diffraction grating corresponding to light in the red wavelength band emitted by a first panel, a second diffraction grating corresponding to light in the green wavelength band emitted by a second panel, and a third diffraction grating corresponding to light in the blue wavelength band emitted by a third panel, each of which is arranged at a different position, and the first diffraction grating is arranged shifted in a direction that increases the angle of incidence on a first reflecting surface of the cross prism that reflects light in the red wavelength band.

[0009] The optical device according to one aspect of the present disclosure may be an independent device or an internal block constituting a single device.

[0010] 1 is a diagram explaining the configuration of a cross prism of an LCD projector. 2 is a diagram explaining the configuration of a Philips-type prism. 3 is a diagram explaining problems with a cross prism. 4 is a diagram illustrating an example configuration of a self-emitting panel and an optical system. 5 is a diagram illustrating the relationship between the radiation angle of a G panel and the angle of incidence on an R-reflecting film in a cross prism. 6 is a diagram illustrating the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by the R-reflecting film. 7 is a diagram illustrating an example configuration of a self-emitting panel and an optical system. 8 is a diagram illustrating the relationship between the radiation angle of a G panel and the angle of incidence on a B-reflecting film in a cross prism. 9 is a diagram illustrating the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by the B-reflecting film. 10 is a diagram illustrating the relationship between the positive and negative radiation angles in a self-emitting panel. 11 is a diagram illustrating the relationship between the radiation angle of an R panel and the angle of incidence on an R-reflecting film in a cross prism. 12 is a diagram illustrating the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by the R-reflecting film. 13 is a diagram illustrating the relationship between the positive and negative radiation angles in a self-emitting panel. 14 is a diagram illustrating the relationship between the radiation angle of a B panel and the angle of incidence on a B-reflecting film in a cross prism. 1 is a diagram showing the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by a B reflecting film. FIG. 1 is a diagram showing an example of the configuration of a cross prism. FIG. 2 is a diagram showing the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by an R reflecting film. FIG. 3 is a diagram showing the relationship between the angle of light incident on a cross prism and the wavelength of light reflected by a B reflecting film. FIG. 4 is a diagram showing an example of the configuration of an optical device used in an eyewear-type wearable device. FIG. 5 is a diagram explaining problems when used in an eyewear-type wearable device. FIG. 6 is a diagram explaining problems when used in an eyewear-type wearable device. FIG. 7 is a diagram explaining the radiation angle characteristics of a self-emitting panel. FIG. 8 is a diagram explaining the radiation angle characteristics of a self-emitting panel. FIG. 9 is a diagram explaining the detailed configuration of a light guide plate. FIG. 10 is a diagram showing a configuration example of an embodiment of an optical device to which the present disclosure is applied. FIG. 11 is a diagram showing another configuration example of an embodiment of an optical device to which the present disclosure is applied. FIG. 12 is a diagram showing another configuration example of an embodiment of an optical device to which the present disclosure is applied. FIG. 13 is a diagram showing another example of the arrangement of diffraction gratings of each color in an incident diffraction grating. FIG. 14 is a diagram showing another configuration example of an optical device.10 is a diagram illustrating another configuration example of an optical device. 11 is a diagram illustrating an example of a configuration of an embodiment of an electronic device to which the present disclosure is applied.

[0011] <Conventional Configuration> Fig. 1 is a diagram illustrating the configuration of a cross prism in a liquid crystal projector. As shown in Fig. 1, in a liquid crystal projector, light from a lamp 11 is separated into red, green, and blue light by an optical system 12 composed of a dichroic mirror and the like, and the light is transmitted through panels 13R, 13G, and 13B and incident on a cross prism 14 where the optical paths are combined. In Fig. 1, panels 13R, 13G, and 13B are composed of liquid crystal panels. The light whose optical paths have been combined by the cross prism 14 is projected by a projection lens 15.

[0012] Of the light incident on the cross prism 14, the dot-dash line in the figure indicates red light, the solid line in the figure indicates green light, and the dashed line in the figure indicates blue light. The light incident on the cross prism 14 is polarized green light as P-polarized light and red and blue light as S-polarized light, ensuring angular characteristics. In other words, the cross prism 14 uses P-polarized light for transmission and S-polarized light for reflection, and is not compatible with unpolarized light.

[0013] FIG. 2 is a diagram illustrating the configuration of a Philips-type prism. Philips-type prisms are called Philips-type because they were developed by Philips. As shown in FIG. 2, a Philips-type prism is provided with a color synthesis prism 21, which sets the angle of incidence close to perpendicular and forms an air gap at the bonding surface to perform color separation and synthesis while maintaining angle dependency. The light whose optical paths have been synthesized by the color synthesis prism 21 is projected by a projection lens 22.

[0014] The size of the Philips prism itself is larger than that of other prisms. This increases the distance from the projection lens 22 to the panel, and the size of the projection lens 22 increases, resulting in a larger overall optical system. Furthermore, because the direction of the optical path of the Philips prism is complex, it is often used for color separation in cameras, but is rarely used in projectors.

[0015] FIG. 3 illustrates the problems with cross prisms. As shown in FIG. 3, cross prism 14 has R-reflecting surface 14R, which is coated with an R-reflecting film that reflects red light, and B-reflecting surface 14B, which is coated with a B-reflecting film that reflects blue light. However, blue light from panel 13B may be transmitted through B-reflecting surface 14B. In this case, as indicated by the dashed arrows in the figure, the blue light transmitted through B-reflecting surface 14B may enter panels 13R and 13G as leakage light. In particular, if wavelength conversion type panels 13R and 13G are used, the leakage blue light may generate unnecessary red and green light.

[0016] As described above, the cross prisms used in three-panel LCD projectors assume linearly polarized light as incident light, and the light utilization efficiency of non-polarized self-luminous panels decreases due to the polarized light. When attempting to achieve non-polarized light with a cross prism, it is difficult to widen the angle characteristics as is, and limiting the angle reduces efficiency. Furthermore, limiting the wavelength (shortening the blue wavelength and lengthening the red wavelength) reduces luminosity, requiring more blue and red light, resulting in reduced efficiency. On the other hand, this places restrictions on the light-emitting device, potentially reducing its efficiency. While Philips-type prisms can achieve angular characteristics with non-polarized light, they suffer from the problem of large size.

[0017] <Configuration of the Present Disclosure> An example configuration of an embodiment of an optical device to which the present disclosure is applied will be described below.

[0018] <<Relationship Between Radiation Angle and Incident Angle>> The relationship between the radiation angle of the panel and the incident angle to the reflective surface (reflective film) in the cross prism will be described. First, the relationship between the radiation angle θ of the green panel and the incident angle φ to the R reflective surface in the cross prism will be described with reference to Figures 4 to 6.

[0019] As shown in FIG. 4, the optical device includes an R panel 31R, a G panel 31G, a B panel 31B, a cross prism 32, and a projection lens 33.

[0020] The R panel 31R is a monochromatic self-emitting panel that emits red light corresponding to the red wavelength band. The G panel 31G is a monochromatic self-emitting panel that emits green light corresponding to the green wavelength band. The B panel 31B is a monochromatic self-emitting panel that emits blue light corresponding to the blue wavelength band. Of the lines from each panel, the dashed lines in the figure represent red light, the solid lines in the figure represent green light, and the dashed lines in the figure represent blue light. The relationship between these lights and line types is the same in other figures described below.

[0021] The cross prism 32 is formed by joining four prisms each having a right-angled isosceles triangle shape, and the joined surfaces have an R-reflecting surface 32R on which an R-reflecting film that reflects red light is formed, and a B-reflecting surface 32B on which a B-reflecting film that reflects blue light is formed. The cross prism 32 reflects the red light incident from the R panel 31R by the R-reflecting surface 32R, transmits the green light incident from the G panel 31G, and reflects the blue light incident from the B panel 31B by the B-reflecting surface 32B, thereby combining the optical paths of the red, green, and blue light.

[0022] The projection lens 33 projects the red light, green light, and blue light whose optical paths have been combined by the cross prism 32 .

[0023] In this way, the optical device is configured using three RGB monochromatic self-emitting panels, and in its optical system, the paths of the light of each color emitted from each monochromatic self-emitting panel are combined by the cross prism 32, and the combined light paths are projected by the projection lens 33. In this way, the optical device can project image light (video light) corresponding to the red, green, and blue light emitted from the RGB monochromatic self-emitting panels.

[0024] Here, the radiation angle θ and the incident angle φ in the optical device will be described, focusing on the G panel 31G and the R reflecting surface 32R in the cross prism 32. Fig. 5 is a diagram showing the relationship between the radiation angle θ of the G panel 31G and the incident angle φ on the R reflecting surface 32R.

[0025] As shown on the left side of Figure 5, it is assumed that the radiation angle θ of the green light radiated (emitted) from the emission surface of the G panel 31G is set such that the clockwise direction is the angle θ+ direction and the counterclockwise direction is the angle θ- direction with respect to the normal direction of the emission surface. In this case, the relationship between the θ+ and θ- directions and the angle of incidence φ on the R reflecting surface 32R as viewed from the G panel 31G is as shown on the right side of Figure 5.

[0026] That is, the θ+ direction is the direction in which the incident angle φ increases, and the θ- direction is the direction in which the incident angle φ decreases. More specifically, when the incident angle onto the R reflecting surface 32R in the normal direction to the output surface of the G panel 31G is φ, the incident angle in the θ+ direction is φ+, and the incident angle in the θ- direction is φ-, the incident angle φ+ is larger than the incident angle φ-.

[0027] 6 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the R reflecting surface 32R. In Fig. 6, the horizontal axis represents wavelength, the vertical axis represents reflectance, P1 represents P-polarized light, and S1 represents S-polarized light.

[0028] 6, solid lines P1 and S1 indicate normal incidence on the cross prism 32, and as the angle of incidence on the cross prism 32 shifts, the reflected wavelength shifts. That is, as viewed from the G panel 31G, the θ+ direction shifts in the direction in which the angle of incidence φ on the R reflecting surface 32R increases, and the reflected wavelength shifts in the direction in which it shortens (dashed lines P1 and S1 in the figure). On the other hand, as viewed from the G panel 31G, the θ- direction shifts in the direction in which the angle of incidence φ on the R reflecting surface 32R decreases, and the reflected wavelength shifts in the direction in which it lengthens (dashed lines P1 and S1 in the figure).

[0029] Next, the relationship between the radiation angle θ of the green panel and the incident angle φ on the B reflecting surface in the cross prism will be described with reference to FIGS.

[0030] 7, the configuration of the optical device is the same as that of Fig. 4, but here, the radiation angle θ and the incident angle φ will be explained, focusing on the G panel 31G and the B reflecting surface 32B in the cross prism 32. Fig. 8 is a diagram showing the relationship between the radiation angle θ of the G panel 31G and the incident angle φ on the B reflecting surface 32B in the cross prism 32.

[0031] As shown on the left side of Figure 8, if the radiation angle θ of green light emitted from the exit surface of G panel 31G is assumed to be θ+, θ-, the relationship between the θ+, θ- directions as viewed from G panel 31G and the angle of incidence φ on B reflecting surface 32B is as shown on the right side of Figure 8.

[0032] That is, the θ+ direction is the direction in which the incident angle φ decreases, and the θ- direction is the direction in which the incident angle φ increases. More specifically, when the incident angle onto the B reflecting surface 32B in the normal direction to the output surface of the G panel 31G is φ, the incident angle in the θ+ direction is φ+, and the incident angle in the θ- direction is φ-, the incident angle φ+ is smaller than the incident angle φ-.

[0033] 9 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the B reflecting surface 32B. In Fig. 9, the horizontal axis represents wavelength, the vertical axis represents reflectance, P2 represents P-polarized light, and S2 represents S-polarized light.

[0034] 9, the solid lines P2 and S2 indicate normal incidence on the cross prism 32, and as the angle of incidence on the cross prism 32 shifts, the reflected wavelength shifts. That is, as viewed from the G panel 31G, the θ+ direction shifts in the direction in which the angle of incidence φ on the B reflecting surface 32B decreases, and the reflected wavelength shifts in the direction in which it increases (dashed lines P2 and S2 in the figure). On the other hand, as viewed from the G panel 31G, the θ- direction shifts in the direction in which the angle of incidence φ on the B reflecting surface 32B increases, and the reflected wavelength shifts in the direction in which it decreases (dashed lines P2 and S2 in the figure).

[0035] Next, the relationship between the radiation angle θ of the red panel and the incident angle φ on the R reflecting surface in the cross prism will be described with reference to FIGS.

[0036] 10, the configuration of the optical device is the same as that in FIG. 4, but here, the radiation angle θ and the incident angle φ will be explained, focusing on the R panel 31R and the R reflecting surface 32R in the cross prism 32. In FIG. 10, the relationship between the positive and negative directions of the radiation angle θ in the R panel 31R, G panel 31G, and B panel 31B is such that the light emitted from the cross prism 32 that heads diagonally upward to the right in the figure is θ+, and the light that heads diagonally upward to the left in the figure is θ-.

[0037] Fig. 11 is a diagram showing the relationship between the radiation angle θ of the R panel 31R and the incident angle φ on the R reflecting surface 32R in the cross prism 32. As shown on the left side of Fig. 11, the radiation angle θ of the red light radiated (emitted) from the emission surface of the R panel 31R is angle θ+ in the counterclockwise direction and angle θ- in the clockwise direction, based on the normal direction to the emission surface. In this case, the relationship between the θ+ and θ- directions and the incident angle φ on the R reflecting surface 32R as viewed from the R panel 31R is as shown on the right side of Fig. 11.

[0038] That is, the θ+ direction is the direction in which the incident angle φ increases, and the θ- direction is the direction in which the incident angle φ decreases. More specifically, when the incident angle onto the R reflecting surface 32R in the normal direction of the exit surface of the R panel 31R is φ, the incident angle in the θ+ direction is φ+, and the incident angle in the θ- direction is φ-, the incident angle φ+ is larger than the incident angle φ-.

[0039] 12 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the R reflecting surface 32R. In Fig. 12, the horizontal axis represents wavelength, the vertical axis represents reflectance, P1 represents P-polarized light, and S1 represents S-polarized light.

[0040] 12, the solid lines P1 and S1 indicate normal incidence on the cross prism 32, and as the angle of incidence on the cross prism 32 shifts, the reflected wavelength shifts. That is, as viewed from the R panel 31R, the θ+ direction shifts in the direction in which the angle of incidence φ on the R reflecting surface 32R increases, and the reflected wavelength shifts in the direction in which it shortens (dashed lines P1 and S1 in the figure). On the other hand, as viewed from the R panel 31R, the θ- direction shifts in the direction in which the angle of incidence φ on the R reflecting surface 32R decreases, and the reflected wavelength shifts in the direction in which it lengthens (dashed lines P1 and S1 in the figure).

[0041] Next, the relationship between the radiation angle θ of the blue panel and the incident angle φ on the B reflecting surface in the cross prism will be described with reference to FIGS.

[0042] 13, the configuration of the optical device is the same as that in Fig. 4, but here, the radiation angle θ and the incident angle φ will be explained, focusing on the B panel 31B and the B reflecting surface 32B in the cross prism 32. Also, in Fig. 13, as in Fig. 10, the relationship between the positive and negative directions of the radiation angle θ in each of the RGB panels is such that the light emitted from the cross prism 32 that is directed diagonally upward to the right in the figure is θ+, and the light that is directed diagonally upward to the left in the figure is θ-.

[0043] Fig. 14 is a diagram showing the relationship between the radiation angle θ of the B panel 31B and the incident angle φ on the B reflecting surface 32B in the cross prism 32. As shown on the left side of Fig. 14, the radiation angle θ of the blue light radiated (emitted) from the emission surface of the B panel 31B is angle θ+ in the counterclockwise direction and angle θ- in the clockwise direction with respect to the normal direction of the emission surface. In this case, the relationship between the θ+ and θ- directions and the incident angle φ on the B reflecting surface 32B as viewed from the B panel 31B is as shown on the right side of Fig. 14.

[0044] That is, the angle θ+ direction is the direction in which the incident angle φ decreases, and the angle θ- direction is the direction in which the incident angle φ increases. More specifically, when the incident angle onto the B reflecting surface 32B in the normal direction to the exit surface of the B panel 31B is φ, the incident angle in the θ+ direction is φ+, and the incident angle in the θ- direction is φ-, the incident angle φ+ is smaller than the incident angle φ-.

[0045] 15 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the B reflecting surface 32B. In Fig. 15, the horizontal axis represents wavelength, the vertical axis represents reflectance, P2 represents P-polarized light, and S2 represents S-polarized light.

[0046] 15, the solid lines P2 and S2 indicate normal incidence on the cross prism 32, and as the angle of incidence on the cross prism 32 shifts, the reflected wavelength shifts. That is, as viewed from the B panel 31B, the θ+ direction shifts in the direction in which the angle of incidence φ on the B reflecting surface 32B decreases, and the reflected wavelength shifts in the direction in which it increases (dashed lines P2 and S2 in the figure). On the other hand, as viewed from the B panel 31B, the θ- direction shifts in the direction in which the angle of incidence φ on the B reflecting surface 32B increases, and the reflected wavelength shifts in the direction in which it decreases (dashed lines P2 and S2 in the figure).

[0047] <<Characteristics of a Non-Polarizing Cross Prism>> The characteristics of a cross prism used with non-polarized light will be described with reference to Figures 16 to 18. In Figure 16, the configuration of the optical device is the same as that in Figure 4, but with regard to the radiation angle θ of the green light emitted from the exit surface of G panel 31G, the light emitted from cross prism 32 heading diagonally upward to the right in the figure is θ+, and the light heading diagonally upward to the left in the figure is θ-.

[0048] Fig. 17 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the R reflecting surface 32R. Fig. 17A shows the case where green light emitted from the G panel 31G is perpendicularly incident on the cross prism 32, and Fig. 17B shows the case where the angle of incidence on the cross prism 32 is shifted. In Figs. 17A and 17B, the horizontal axis is wavelength and the vertical axis is reflectance, with P1 representing P-polarized light and S1 representing S-polarized light.

[0049] In Figures 17A and 17B, the solid lines P1 and S1 indicate normal incidence on the cross prism 32. However, if the angle of incidence shifts, the wavelength reflected by the R reflecting surface 32R shifts in the θ+ direction or the θ- direction, as shown by the dashed lines P1 and S1 and the dashed-dotted lines P1 and S1 in Figure 17B. Thus, if the angle of incidence on the cross prism 32 shifts, the wavelength reflected by the R reflecting surface 32R shifts. That is, as viewed from the G panel 31G, the θ+ direction shifts in the direction in which the angle of incidence on the R reflecting surface 32R increases, and the reflected wavelength shifts in the direction in which the reflected wavelength decreases (dashed lines P1 and S1 in the figures). On the other hand, as viewed from the G panel 31G, the θ- direction shifts in the direction in which the angle of incidence on the R reflecting surface 32R decreases, and the reflected wavelength shifts in the direction in which the reflected wavelength increases (dashed lines P1 and S1 in the figures).

[0050] Fig. 18 is a diagram showing the relationship between the angle of light incident on the cross prism 32 and the wavelength of light reflected by the B reflecting surface 32B. Fig. 18A shows the case where green light emitted from the G panel 31G is perpendicularly incident on the cross prism 32, and Fig. 18B shows the case where the angle of incidence on the cross prism 32 is shifted. In Figs. 18A and 18B, the horizontal axis is wavelength and the vertical axis is reflectance, with P2 representing P-polarized light and S2 representing S-polarized light.

[0051] In Figures 18A and 18B, the solid lines P2 and S2 indicate normal incidence on the cross prism 32. However, if the angle of incidence shifts, the wavelength reflected by the B reflecting surface 32B shifts in the θ+ direction or the θ- direction, as shown by the dashed lines P2 and S2 and the dashed-dotted lines P2 and S2 in Figure 18B. Thus, if the angle of incidence on the cross prism 32 shifts, the wavelength reflected by the B reflecting surface 32B shifts. That is, as viewed from the G panel 31G, the θ+ direction shifts in the direction in which the angle of incidence on the B reflecting surface 32B decreases, and the reflected wavelength shifts in the direction in which it increases (dashed lines P2 and S2 in the figures). On the other hand, as viewed from the G panel 31G, the θ- direction shifts in the direction in which the angle of incidence on the R reflecting surface 32R increases, and the reflected wavelength shifts in the direction in which it decreases (dashed lines P2 and S2 in the figures).

[0052] Therefore, the θ+ direction is the direction in which the transmission wavelength width (transmission band) of green light narrows, and the θ- direction is the direction in which the transmission wavelength width of green light widens but the wavelength widths of red and blue light narrow.

[0053] <<Eyewear-type configuration>> The optical device described above can be used in eyewear-type wearable devices such as glasses. Fig. 19 is a diagram showing an example configuration of an optical device used in an eyewear-type wearable device. In Fig. 19, the optical device further includes a light guide plate 41 in addition to the R panel 31R, G panel 31G, B panel 31B, cross prism 32, and projection lens 33.

[0054] Image light (video light) projected from the projection lens 33 is incident on the light guide plate 41, propagates inside, and is output to the outside. The light guide plate 41 has an input diffraction grating and an output diffraction grating. The input diffraction grating receives the image light, diffracts the incident image light, and causes it to propagate inside the light guide plate 41. The output diffraction grating diffracts the image light that has propagated inside the light guide plate 41, and outputs it to the outside of the light guide plate 41 (to the eye of a user wearing an eyewear-type wearable device).

[0055] Here, let us consider a case where the pupil of the projection lens 33 is placed at the entrance portion (incident diffraction grating) of the light guide plate 41, and the angular radiation characteristics from the panel are made uniform. In this case, depending on the angle, the spectrum is cut off, and dark areas appear in the distribution within the pupil. Also, a color shift occurs.

[0056] Figure 20 is a diagram showing the relationship between red, green, and blue wavelengths and the shift in reflected wavelength depending on the θ+ direction or the θ- direction. In Figures 20A to 20C, the horizontal axis also represents wavelength and the vertical axis represents reflectance. In Figures 20A to 20C, R represents the waveform corresponding to the red wavelength band, G represents the waveform corresponding to the green wavelength band, and B represents the waveform corresponding to the blue wavelength band. Furthermore, P1 and P2 represent P-polarized light, and S1 and S2 represent S-polarized light, which correspond to the P-polarized light and S-polarized light in Figures 17 and 18.

[0057] Fig. 20B shows the case where green light emitted from the G panel 31G is perpendicularly incident. In Fig. 20B, the solid lines P1 and S1 correspond to the solid lines P1 and S1 in Fig. 17A, and the solid lines P2 and S2 correspond to the solid lines P2 and S2 in Fig. 18A. In the case of perpendicular incidence, the reflected wavelength does not shift.

[0058] Figure 20A shows a case where the green light emitted from the G panel 31G is shifted toward the θ-side. In Figure 20A, the dashed-dotted lines P1 and S1 correspond to the dashed-dotted lines P1 and S1 in Figure 17B, and when shifted toward the θ-side, the reflected wavelength shifts toward longer wavelengths. Also, the dashed-dotted lines P2 and S2 correspond to the dashed-dotted lines P2 and S2 in Figure 18B, and when shifted toward the θ-side, the reflected wavelength shifts toward shorter wavelengths.

[0059] Figure 20C shows a case where the green light emitted from the G panel 31G is shifted toward the θ+ side. In Figure 20C, the dashed lines P1 and S1 in the figure correspond to the dashed lines P1 and S1 in Figure 17B, and when shifted toward the θ+ side, the reflected wavelength shifts toward a shorter wavelength. Furthermore, the dashed lines P2 and S2 in the figure correspond to the dashed lines P2 and S2 in Figure 18B, and when shifted toward the θ+ side, the reflected wavelength shifts toward a longer wavelength.

[0060] In this way, when the angle of incidence on the cross prism 32 shifts in the θ+ direction or the θ- direction, the wavelengths reflected by the R reflecting surface 32R and the B reflecting surface 32B shift, and depending on the angle, dark areas appear in the distribution within the pupil. Figure 21 shows the distribution within the pupil for each of green (G), red (R), and blue (B) light.

[0061] As shown by the circle on the left side of Fig. 21, the distribution of green (G) is the desired distribution in the dotted pattern area, but the black area is dark. That is, the green light is dark on the θ+ side. Also, as shown by the circle in the center of Fig. 21, the distribution of red (R) is the desired distribution in the dotted pattern area, but the black area is dark, so the green light is dark on the θ- side. As shown by the circle on the right side of Fig. 21, the distribution of blue (B) is the desired distribution in the dotted pattern area, but the black area is dark, so the green light is dark on the θ- side.

[0062] In this way, the distribution within the pupil is such that green is darker on the θ+ side, and red and blue are darker on the θ- side. Also, a shift in the reflected wavelength causes a color shift. As a result, color unevenness and a decrease in efficiency occur.

[0063] <<Configuration of Self-Emitting Panel>> The radiation angle characteristics of a self-emitting panel will be described with reference to Figures 22 and 23. In a monochromatic self-emitting panel composed of an R panel 31R, a G panel 31G, and a B panel 31B, a plurality of pixels are arranged two-dimensionally in the panel area. As shown in Figure 22A, in a monochromatic self-emitting panel, a pixel is composed of a light-emitting area 62 formed on a silicon substrate 61. Furthermore, a microlens 63 is arranged for each pixel, and light emitted in the light-emitting area 62 is radiated through the microlens 63.

[0064] Fig. 22B is a diagram showing an example of a radiation intensity profile when light is emitted from the structure of Fig. 22A. In Fig. 22B, the profile has a peak in radiation intensity when the radiation angle θ is 0°. In the structure of Fig. 22A, the radiation intensity profile can be offset in the angular direction by decentering the microlens 63 with respect to the light-emitting region 62.

[0065] Fig. 23A shows a structure in which the microlens 63 is decentered with respect to the light-emitting region 62. Fig. 23B shows an example of a profile of radiation intensity when light is emitted from the structure of Fig. 23A. Comparing the profile shown in Fig. 23B with the profile shown in Fig. 22B, the peak of radiation intensity is shifted to the right.

[0066] 24 and 25 , the detailed configuration of the light guide plate 41 will be described. In Fig. 24 , light (image light) emitted from a monochrome self-emitting panel 42 is incident on the light guide plate 41 by a projection lens 43. The light guide plate 41 has an entrance diffraction grating 51 and an exit diffraction grating 52, and the image light projected by the projection lens 43 is incident on the entrance diffraction grating 51.

[0067] The incident diffraction grating 51 diffracts the image light incident on the surface of the light guide plate 41 and causes the light to propagate inside the light guide plate 41. The incident diffraction grating 51 is formed on the front surface, the back surface, or both surfaces of the light guide plate 41. Here, the surface of the light guide plate 41 facing the projection lens 43 can be referred to as the back surface, and the surface opposite thereto can be referred to as the front surface. The image light diffracted by the incident diffraction grating 51 into the light guide plate 41 is propagated by total internal reflection.

[0068] The output diffraction grating 52 diffracts a portion of the image light that has propagated inside the light guide plate 41, and outputs the light to the outside of the light guide plate 41 (to the user's eye 40). Because the output diffraction grating 52 diffracts a portion of the light, the user can view the image (video) even if the position of the eye 40 changes.

[0069] 24, the dashed line indicates red light, the solid line indicates green light, and the dashed line indicates blue light, and one light guide plate is used for RGB, but it is also possible to adopt a configuration in which a dedicated light guide plate is provided for each of RGB, or a configuration in which one light guide plate is used for two colors. The incident diffraction grating 51 is also called an ICG (In Coupling Grating), and the exit diffraction grating 52 is also called an OCG (Out Coupling Grating).

[0070] Fig. 25 schematically shows how image light incident on light guide plate 41 propagates inside light guide plate 41 and is guided to user's eye 40. Fig. 25 shows the configuration when the surface of light guide plate 41 is shown in the directions of the X axis and Y axis, and light guide plate 41 is viewed from the direction of the Z axis, which is orthogonal to the X axis and Y axis. The arrows in the figure indicate the direction of light.

[0071] As shown in FIG. 25 , the light guide plate 41 can have three diffraction grating regions: an input diffraction grating 51, an output diffraction grating 52, and a light guide diffraction grating 53. The input diffraction grating 51 is a region where image light from the monochrome self-emitting panel 42 is incident via the projection lens 43 and guided into the light guide plate 41. The output diffraction grating 52 is a region where a portion of the image light propagating through the light guide plate 41 is diffracted and guided to the user's eye 40. The light output from the output diffraction grating 52 is spread in a second direction (Y direction in the figure). The light guide diffraction grating 53 is a region where a portion of the image light incident into the light guide plate 41 is diffracted and spread in a first direction (X direction in the figure) perpendicular to the second direction.

[0072] In the light guide plate 41, the light guide diffraction grating 53 is not an essential region, and when the light guide diffraction grating 53 is not provided, for example, the exit diffraction grating 52 may spread the light in two directions, a first direction and a second direction (X and Y directions in the figure), while guiding the image light to the user's eye 40. Furthermore, even when the region of the entrance diffraction grating 51 is small, the user can view the image (video) by spreading the light with the exit diffraction grating 52 and the light guide diffraction grating 53, even if the position of the eye 40 changes.

[0073] <<Configuration of Optical Device>> Figures 26 and 27 are diagrams showing an example configuration of an embodiment of an optical device to which the present disclosure is applied. In Figures 26 and 27, the relationship between the X, Y, and Z axes is the same as in Figure 25, and Figure 26 shows the configuration when viewed from the X-axis direction, and Figure 27 shows the configuration when viewed from the Z-axis direction.

[0074] 26, the optical device 1 includes an R panel 31R, a G panel 31G, a B panel 31B, a cross prism 32, a projection lens 33, and a light guide plate 41. The R panel 31R emits red light corresponding to the image. The G panel 31G emits green light corresponding to the image. The B panel 31B emits blue light corresponding to the image.

[0075] The cross prism 32 has an R reflecting surface 32R and a B reflecting surface 32B, and combines the optical paths of the red light, green light, and blue light by reflecting the red light incident from the R panel 31R by the R reflecting surface 32R, transmitting the green light incident from the G panel 31G, and reflecting the blue light incident from the B panel 31B by the B reflecting surface 32B.

[0076] The cross prism 32 combines the optical paths of the red light, green light, and blue light within a plane including a second axis (Y axis) that is perpendicular to a first axis (X axis) that corresponds to a first direction (X direction) in which the image light is diffracted and propagated by the light guide plate 41, and a third axis (Z axis, optical axis) that corresponds to the direction in which the image light is incident on the light guide plate 41. The projection lens 33 projects the red light, green light, and blue light, the optical paths of which have been combined by the cross prism 32, onto the light guide plate 41 as image light.

[0077] The light guide plate 41 is provided with an incident diffraction grating 51 that diffracts image light incident on the surface of the light guide plate 41 and propagates inside the plate. The incident diffraction grating 51 has a diffraction grating 51R corresponding to red light, a diffraction grating 51G corresponding to green light, and a diffraction grating 51B corresponding to blue light. That is, the incident diffraction grating 51 has regions for the diffraction grating 51R, the diffraction grating 51G, and the diffraction grating 51B corresponding to the incident red, green, and blue light.

[0078] Diffraction grating 51R diffracts incident red light and causes it to propagate inside light guide plate 41. Diffraction grating 51G diffracts incident green light and causes it to propagate inside light guide plate 41. Diffraction grating 51B diffracts incident blue light and causes it to propagate inside light guide plate 41.

[0079] 27 , diffraction gratings 51R, 51G, and 51B are arranged at offset positions in incident diffraction grating 51. In Fig. 27 , the direction of image light propagating inside light guide plate 41 is indicated by rightward and downward arrows, but diffraction gratings 51G, 51B, and 51R are arranged at offset positions in a second direction (Y direction in the drawing) that is substantially perpendicular to a first direction (X direction in the drawing) in which the image light is diffracted and propagated by incident diffraction grating 51.

[0080] Specifically, diffraction grating 51R is disposed so as to be shifted in a direction in which the angle of incidence on R-reflecting surface 32R of cross prism 32 increases (for example, the θ+ direction and φ+ direction in FIG. 11 ). Diffraction grating 51G is disposed so as to be shifted in a direction in which the angle of incidence on R-reflecting surface 32R of cross prism 32 decreases (for example, the θ- direction and φ- direction in FIG. 5 ). Diffraction grating 51B is disposed so as to be shifted in a direction in which the angle of incidence on B-reflecting surface 32B of cross prism 32 decreases (for example, the θ+ direction and φ+ direction in FIG. 14 ).

[0081] Self-emitting panels such as the R panel 31R, G panel 31G, and B panel 31B have a characteristic in which the luminous efficiency of red and green light is lower than the luminous efficiency of blue light. Therefore, to minimize (e.g., minimize) the loss of red and green light, the diffraction gratings 51R, 51G, and 51B can be offset to prioritize the diffraction gratings 51R and 51G. For example, of the diffraction gratings 51R, 51G, and 51B, only the diffraction grating 51R may be shifted in a direction that increases the angle of incidence on the R-reflecting surface 32R of the cross prism 32. Alternatively, of the diffraction gratings 51R, 51G, and 51B, the diffraction grating 51R may be shifted in a direction that increases the angle of incidence on the R-reflecting surface 32R, and the diffraction grating 51G may be shifted in a direction that decreases the angle of incidence on the R-reflecting surface 32R.

[0082] In addition, the peak directions (peak radiation angles) of the light emitted from each of the R panel 31R, G panel 31G, and B panel 31B are shifted for red, green, and blue light, and the direction of the shift corresponds to the positions at which the diffraction gratings 51R, 51G, and 51B are arranged on the incident diffraction grating 51.

[0083] Specifically, the peak of the radiation angle θ of the red light emitted (emitted) from the R panel 31R is shifted in a direction in which the angle of incidence on the R reflecting surface 32R of the cross prism 32 increases (for example, the θ+ direction and φ+ direction in FIG. 11 ). The peak of the radiation angle θ of the green light emitted from the G panel 31G is shifted in a direction in which the angle of incidence on the R reflecting surface 32R of the cross prism 32 decreases (for example, the θ- direction and φ- direction in FIG. 5 ). The peak of the radiation angle θ of the blue light emitted from the B panel 31B is shifted in a direction in which the angle of incidence on the B reflecting surface 32B of the cross prism 32 decreases (for example, the θ+ direction and φ+ direction in FIG. 14 ).

[0084] Here, each of the self-emitting panels, the R panel 31R, the G panel 31G, and the B panel 31B, has a small lens provided with respect to the light-emitting area or a microstructure that offsets the optical axis, thereby realizing an offset in the radiation angle characteristics. For example, as shown in Figures 22 and 23, in a self-emitting panel, by decentering a microlens 63 with respect to a light-emitting area 62, the radiation intensity profile can be offset in the angular direction.

[0085] In the optical device 1 configured as described above, loss due to the cross prism 32 is reduced, and the occurrence of color unevenness and the like is suppressed in the light (image light) output to the outside from the output diffraction grating 52, thereby obtaining a highly uniform image. As described above, when the pupil of the projection lens 33 is disposed at the input diffraction grating 51 of the light guide plate 41 as shown in FIG. 21 , there is a risk of a phenomenon in which green becomes dark on the θ+ side and red and blue become dark on the θ− side in the distribution within the pupil. In the optical device 1, the peak of the radiation angle θ of green light, i.e., the position of the diffraction grating 51G, is shifted in the direction of decreasing the angle of incidence on the R-reflecting surface 32R, the peak of the radiation angle θ of red light, i.e., the position of the diffraction grating 51R, is shifted in the direction of increasing the angle of incidence on the R-reflecting surface 32R, and the peak of the radiation angle θ of blue light, i.e., the position of the diffraction grating 51B, is shifted in the direction of decreasing the angle of incidence on the B-reflecting surface 32B, thereby preventing the occurrence of such a phenomenon.

[0086] Figures 28 and 29 are diagrams showing another example configuration of an embodiment of an optical device to which the present disclosure is applied. In Figures 28 and 29, the relationship between the X, Y, and Z axes is the same as in Figures 26 and 27, and Figure 28 shows the configuration when viewed from the X-axis direction, and Figure 29 shows the configuration when viewed from the Z-axis direction.

[0087] 28, optical device 1 is configured to include two light guide plates, ie, light guide plate 41-1 and light guide plate 41-2, instead of light guide plate 41, as compared to the configuration in FIG. 26. Light guide plate 41-1 and light guide plate 41-2 are installed a predetermined distance apart. Light guide plate 41-1 is provided with incident diffraction grating 51-1 having diffraction grating 51R and diffraction grating 51G. Light guide plate 41-2 is provided with incident diffraction grating 51-2 having diffraction grating 51B.

[0088] As shown in Figure 29, when light guide plate 41-1 and light guide plate 41-2 are viewed in an overlapping state from the Z-axis direction, diffraction grating 51G of incident diffraction grating 51-1, diffraction grating 51B of incident diffraction grating 51-2, and diffraction grating 51R of incident diffraction grating 51-1 are positioned at offset positions. When two light guide plates are used, the diffraction gratings can be arranged side by side in the X direction to prevent light diffracted by the diffraction grating of each color from re-entering the diffraction grating of the other color. In Figure 29, diffraction grating 51B of incident diffraction grating 51-2 and diffraction grating 51R of incident diffraction grating 51-1 are arranged side by side in the X direction. The directions in which the radiation intensity of each self-emitting panel of R panel 31R, G panel 31G, and B panel 31B increases (peak directions) are offset in the directions corresponding to diffraction gratings 51R, 51G, and 51B.

[0089] 28 and 29 show the case where two light guide plates are used, three or more light guide plates may also be used. That is, at least one light guide plate can be used in optical device 1, and when two or more light guide plates are used, diffraction grating 51R, diffraction grating 51G, and diffraction grating 51B may be disposed on one of the light guide plates.

[0090] FIG. 30 is a diagram showing another example of the arrangement of the diffraction gratings of each color in the incident diffraction grating 51 of the light guide plate 41. In FIG.

[0091] 27 shows an example in which diffraction gratings 51G, 51B, and 51R are arranged offset in the direction perpendicular to the direction in which incident light is diffracted and propagated (Y direction), but the diffraction grating regions of each color have a common pitch, so they may overlap. On the right side of A in Fig. 30, of diffraction gratings 51G, 51B, and 51R arranged side by side in the Y direction, at least a portion of the region of diffraction grating 51G and the region of diffraction grating 51B, and at least a portion of the region of diffraction grating 51B and the region of diffraction grating 51R overlap.

[0092] 29 shows an example in which, of diffraction gratings 51G, 51B, and 51R, diffraction gratings 51B and 51R are arranged side by side in the X direction, but the diffraction grating regions of each color may overlap. On the right side of FIG. 30B, at least a portion of the diffraction grating 51G region, the diffraction grating 51B region, and the diffraction grating 51R region overlap. The incidence efficiency of diffraction gratings 51R, 51G, and 51B can be improved by optimizing the shape other than the pitch for each wavelength.

[0093] <<Other Configuration Examples>> Figures 31 and 32 are diagrams showing other configuration examples of the optical device 1 of Figure 26. In Figures 31 and 32, parts corresponding to those in Figure 26 are given the same reference numerals, and descriptions thereof will be omitted.

[0094] 31 , color absorbing members 71 that absorb blue light are disposed between the cross prism 32 and the R panel 31R, and between the cross prism 32 and the G panel 31G. By providing the color absorbing members 71, even when blue light emitted from the B panel 31B passes through the B reflecting surface 32B and becomes leaked light, the leaked light can be prevented from entering the R panel 31R and the G panel 31G.

[0095] The color absorbing member 71 is composed of, for example, color absorbing glass, color absorbing film, or color filter. The color absorbing member 71 may be attached to the cross prism 32, but since absorbing light causes a temperature rise, it is desirable to have an air layer between the R panel 31R and the G panel 31G. The color absorbing member 71 may be disposed on both the R panel 31R side and the G panel 31G side, or may be disposed on at least one of the R panel 31R side and the G panel 31G side.

[0096] 32, the cross prism 32 has an air gap layer 81 formed on the R reflecting surface 32R on which an R reflecting film is formed, and a B reflecting surface 32B on which a B reflecting film is formed, and is bonded with an adhesive. In FIG. 32, the cross prism 32 has a rectangular parallelepiped shape and has an air gap in the R reflecting layer, which allows for a wider angle characteristic of R reflection.

[0097] <<Configuration of Electronic Device>> The optical device 1 can be applied to electronic devices including eyewear-type wearable devices such as AR glasses and OST (Optical See-Through) glasses. Fig. 33 is a diagram showing a configuration example of an embodiment of an electronic device to which the present disclosure is applied. Fig. 33 shows a schematic diagram of an electronic device configured as an eyewear-type wearable device as viewed from above.

[0098] 33, the electronic device 101 includes a frame 111 worn on the user's head and an optical device 1 (see, for example, FIG. 26) attached to the frame 111. The optical device 1 has a light guide plate 41 and an image generation device 122. For example, the R panel 31R, the G panel 31G, the B panel 31B, the cross prism 32, the projection lens 33, and the like are included in the image generation device 122. In FIG. 33, the electronic device 101 is a binocular type including two optical devices 1. However, it may also be a monocular type including one optical device 1. Light (image light) from the image generation device 122 propagates through the semi-transmissive (see-through) light guide plate 41 by total reflection and is emitted toward the user's eye (pupil).

[0099] The frame 111 is composed of a front section 112 disposed in front of the user, two temple sections 113 rotatably attached to both ends of the front section 112 via hinges, and end sections 114 attached to the tip of each temple section 113. The end sections 114 are also called ear tips, earmuffs, or ear pads. Wiring (such as signal lines and power lines) extending from the image generating device 122 passes through the temple sections 113 and the inside of the end sections 114, extends from the tip of the end sections 114 to the outside, and is connected to the control device 121. In addition, a headphone section 115 is connected to the wiring (headphone wiring) extending from the image generating device 122.

[0100] The electronic device 101 is not limited to wearable devices such as AR glasses, OST glasses, etc., and can be applied to various types of head mounted displays (HMDs). Furthermore, the image presented to the user may include an image (video) to be presented to the user in order to realize cross reality (XR) including augmented reality (AR), virtual reality (VR), mixed reality (MR), etc.

[0101] As described above, the present disclosure can reduce light loss due to a cross prism when used with unpolarized light. Specifically, by shifting the position of the incident diffraction grating (ICG) of the light guide plate provided downstream of the cross prism for red, green, and blue light, the loss of light emitted from the unpolarized self-emitting panel due to the cross prism can be reduced. Furthermore, by offsetting the radiation angle characteristics using optical means such as small lenses (microlenses) provided for each pixel in the self-emitting panel, efficiency (light utilization efficiency) can be improved. Furthermore, by aligning the characteristics of the reflective surface (reflective film) of the cross prism, the position of the incident diffraction grating (ICG) of the light guide plate, and the radiation angle characteristics (light distribution characteristics) of the self-emitting panel, more efficient and uniform images (videos) can be presented. For example, when applied to eyewear-type wearable devices, images with reduced color unevenness can be presented to the user.

[0102] Furthermore, when using a cross prism with unpolarized light, a thin air gap layer can be inserted into the R-reflective layer of the cross prism to broaden the angle dependency, resulting in a more efficient optical system. This improved efficiency allows for reduced power consumption and longer use when applied to, for example, eyewear-type wearable devices. Furthermore, reduced heat generation makes it easier to take measures to dissipate heat.

[0103] It should be noted that the embodiments of the present disclosure are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be achieved. In the drawings, red light is represented by a dashed-dotted line, green light by a solid line, and blue light by a dashed line, but these lines may be shifted as appropriate, for example, from the actual reflection position, to make them easier to distinguish from other lines.

[0104] The present disclosure can also be configured as follows.

[0105] (1) A light emitting device comprising: a first panel that emits first light corresponding to a red wavelength band; a second panel that emits second light corresponding to a green wavelength band; a third panel that emits third light corresponding to a blue wavelength band; a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and that combines the optical paths of the first light, the second light, and the third light; a projection lens that projects the light whose optical paths are combined by the cross prism as image light; and a light guide plate that receives the image light projected from the projection lens, propagates therethrough, and emits it to the outside, wherein the light guide plate has: an input diffraction grating that receives the image light and diffracts the input image light to propagate it inside the light guide plate; and an output diffraction grating that diffracts the image light that has propagated inside the light guide plate and emits it to the outside of the light guide plate, An optical device wherein the incident diffraction grating is composed of a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, the first diffraction grating, the second diffraction grating, and the third diffraction grating are arranged at different positions, and the first diffraction grating is arranged so as to be shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes larger. (2) The optical device described in (1), wherein the second diffraction grating is arranged so as to be shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes smaller. (3) The optical device described in (1) or (2), wherein the third diffraction grating is arranged so as to be shifted in a direction in which the angle of incidence on the second reflecting surface of the cross prism becomes smaller. (4) The optical device according to any one of (1) to (3), wherein the first diffraction grating, the second diffraction grating, and the third diffraction grating are arranged to be shifted in a second direction that is a direction substantially perpendicular to a first direction in which the image light is diffracted and propagated by the incident diffraction grating. (5) The optical device according to any one of (1) to (4), wherein the second diffraction grating is arranged to be shifted in a second direction that is a direction substantially perpendicular to the first direction in which the image light is diffracted and propagated by the incident diffraction grating.(6) The optical device according to any one of (1) to (5), wherein the third diffraction grating is arranged to be shifted with respect to the first diffraction grating and the second diffraction grating in a second direction that is a direction approximately perpendicular to a first direction in which the image light is diffracted and propagated by the incident diffraction grating. (7) The optical device according to any one of (1) to (6), wherein the cross prism combines the optical paths of the first light, the second light, and the third light within a plane that includes a second axis that is an axis perpendicular to a first axis that corresponds to the first direction in which the image light is diffracted and propagated by the incident diffraction grating in the light guide plate, and a third axis that corresponds to the direction in which the image light is incident on the light guide plate. (8) The optical device according to any one of (1) to (7), wherein the peak directions of the first light emitted from the first panel, the second light emitted from the second panel, and the third light emitted from the third panel are shifted in directions corresponding to the positions of the first diffraction grating, the second diffraction grating, and the third diffraction grating in the incident diffraction grating. (9) The optical device according to (8), wherein the first panel, the second panel, and the third panel have small lenses or microstructures that offset the optical axes with respect to the light-emitting regions, and the offset in radiation angle characteristics is achieved by the microstructures. (10) The optical device according to any one of (1) to (9), wherein the cross prism has an air gap layer formed on the first reflecting surface, and the second reflecting surface is bonded with an adhesive.(11) A light emitting device comprising: a first panel that emits first light corresponding to a red wavelength band; a second panel that emits second light corresponding to a green wavelength band; a third panel that emits third light corresponding to a blue wavelength band; a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and that combines optical paths of the first light, the second light, and the third light; a projection lens that projects the light whose optical paths are combined by the cross prism as image light; and a light guide plate that receives the image light projected from the projection lens, propagates therethrough, and emits it to the outside, wherein the light guide plate has: an input diffraction grating that receives the image light and diffracts the input image light to propagate it inside the light guide plate; and an output diffraction grating that diffracts the image light that has propagated inside the light guide plate and emits it to the outside of the light guide plate, an incident diffraction grating including a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, the first diffraction grating, the second diffraction grating, and the third diffraction grating being arranged at different positions, and the first diffraction grating being arranged shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes larger.

[0106] DESCRIPTION OF SYMBOLS 1 Optical device, 31R R panel, 31G G panel, 31B B panel, 32 Cross prism, 32R R reflecting surface, 32B B reflecting surface, 33 Projection lens, 41 Light guide plate, 41-1, 41-2 Light guide plate, 51 Incident diffraction grating, 51-1, 51-2 Incident diffraction grating, 51R, 51G, 51B Diffraction grating, 52 Exit diffraction grating, 61 Silicon substrate, 62 Light-emitting region, 63 Microlens, 71 Color absorption member, 81 Air gap layer, 101 Electronic device

Claims

1. A light emitting device comprising: a first panel that emits first light corresponding to a red wavelength band; a second panel that emits second light corresponding to a green wavelength band; a third panel that emits third light corresponding to a blue wavelength band; a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and combines the optical paths of the first light, the second light, and the third light; a projection lens that projects the light whose optical paths have been combined by the cross prism as image light; and a light guide plate onto which the image light projected from the projection lens is incident, propagates inside, and is output to the outside, wherein the light guide plate has: an input diffraction grating that receives the image light and diffracts the incident image light to propagate inside the light guide plate; and an output diffraction grating that diffracts the image light that has propagated inside the light guide plate and is output to the outside of the light guide plate, an incident diffraction grating including a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, the first diffraction grating, the second diffraction grating, and the third diffraction grating being arranged at different positions, and the first diffraction grating being arranged so as to be shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes larger.

2. The optical device according to claim 1, wherein the second diffraction grating is positioned so as to be shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes smaller.

3. The optical device according to claim 1, wherein the third diffraction grating is positioned so as to be shifted in a direction in which the angle of incidence on the second reflecting surface of the cross prism becomes smaller.

4. The optical device according to claim 1, wherein the first diffraction grating, the second diffraction grating, and the third diffraction grating are arranged offset in a second direction that is substantially perpendicular to a first direction in which the image light is diffracted and propagated by the incident diffraction grating.

5. The optical device according to claim 2, wherein the second diffraction grating is positioned offset from the first diffraction grating and the third diffraction grating in a second direction that is substantially perpendicular to a first direction in which the image light is diffracted and propagated by the incident diffraction grating.

6. The optical device according to claim 3, wherein the third diffraction grating is arranged offset from the first diffraction grating and the second diffraction grating in a second direction that is substantially perpendicular to a first direction in which the image light is diffracted and propagated by the incident diffraction grating.

7. The optical device of claim 1, wherein the cross prism combines the optical paths of the first light, the second light, and the third light within a plane including a second axis that is perpendicular to a first axis corresponding to a first direction in which the image light is diffracted and propagated by the incident diffraction grating in the light guide plate, and a third axis corresponding to a direction in which the image light is incident on the light guide plate.

8. The optical device according to claim 1, wherein the peak directions of the first light emitted from the first panel, the second light emitted from the second panel, and the third light emitted from the third panel are shifted in directions corresponding to the positions of the first diffraction grating, the second diffraction grating, and the third diffraction grating in the incident diffraction grating.

9. The optical device according to claim 8, wherein the first panel, the second panel, and the third panel have small lenses or microstructures that offset the optical axes relative to the light-emitting areas, and the offset in radiation angle characteristics is achieved by the microstructures.

10. The optical device according to claim 1, wherein the cross prism has an air gap layer formed on the first reflecting surface, and the second reflecting surface is bonded with an adhesive.

11. A light emitting device comprising: a first panel that emits first light corresponding to a red wavelength band; a second panel that emits second light corresponding to a green wavelength band; a third panel that emits third light corresponding to a blue wavelength band; a cross prism that has a first reflecting surface that reflects the first light and a second reflecting surface that reflects the third light and that combines the optical paths of the first light, the second light, and the third light; a projection lens that projects the light whose optical paths are combined by the cross prism as image light; and a light guide plate onto which the image light projected from the projection lens is incident, propagates inside, and is output to the outside, wherein the light guide plate has: an input diffraction grating that receives the image light and diffracts the incident image light to propagate inside the light guide plate; and an output diffraction grating that diffracts the image light that has propagated inside the light guide plate and is output to the outside of the light guide plate, an incident diffraction grating including a first diffraction grating corresponding to the first light, a second diffraction grating corresponding to the second light, and a third diffraction grating corresponding to the third light, the first diffraction grating, the second diffraction grating, and the third diffraction grating being arranged at different positions, and the first diffraction grating being arranged shifted in a direction in which the angle of incidence on the first reflecting surface of the cross prism becomes larger.

Images