Display device and projection device

Abstract

The present invention provides a light source device that can suppress the increase in size, and a projection device equipped with this light source device. [Solution] The display device 20 includes a light-emitting module which includes a light-emitting section in which a plurality of light sources 36R, 36G, 36B that emit coherent light of different colors are arranged on the same plane; three diffractive optical elements 40R, 40G, 40B which are provided to correspond to different light emission colors for each light source 36R, 36G, 36B and are diffracted when light from each light source 36R, 36G, 36B is incident on them; and a liquid crystal display element 50 which is irradiated with light diffracted by each diffractive optical element 40R, 40G, 40B from the light emitted from each light source 36R, 36G, 36B. Each diffractive optical element 40R, 40G, 40B is positioned to irradiate the liquid crystal display element 50 with light that has a different diffraction angle depending on the color of the incident light.

Description

Technical Field

[0001] The present invention relates to a display device and a projection device.

Background Art

[0002] Conventionally, a projection device including a display device that diffracts light from a light source such as a laser diode by a diffractive optical element (DOE; Diffractive Optical Element) and irradiates a display element to generate image light has been disclosed. For example, Patent Document 1 discloses a projector including a projection unit having an illumination device including a laser light source device that emits red laser light, an illumination device including a laser light source device that emits green laser light, and an illumination device including a laser light source device that emits blue laser light. Each illumination device includes a diffractive optical element that generates diffracted light from the incident laser light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In each illumination device of the projector disclosed in Patent Document 1 above, the incident surface illuminated by each illumination device is provided at a position where the 0th-order light generated from the diffractive optical element does not enter. However, each diffractive optical element provided in each illumination device is dispersedly arranged around the dichroic mirror and emits light toward the dichroic mirror, that is, in different directions, so there is a risk that the device will become large-sized.

[0005] In view of the above points, an object of the present invention is to provide a light source device capable of suppressing an increase in size and a projection device including this light source device.

Means for Solving the Problems

[0006] The display device of the present invention includes a light-emitting module including a light-emitting section in which a plurality of light sources emitting coherent light of different colors are arranged on the same plane; a plurality of diffractive optical elements provided to correspond to each of the plurality of light sources for each different light emission color, and which are incident on and diffracted by light from the plurality of light sources; and an irradiated object to which light diffracted by each of the diffractive optical elements from the light emitted from the plurality of light sources is irradiated. Each of the plurality of diffractive optical elements is positioned to irradiate the irradiated object with light having different diffraction angles depending on the difference in the color of the incident light.

[0007] The projection apparatus of the present invention comprises a display element that generates image light, a display device, and a projection optical system that projects the image light generated by the display element onto the projection object. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a light source device that can suppress the increase in size, and a projection device equipped with this light source device. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic plan view showing the general configuration of a projection device equipped with a display device according to an embodiment. [Figure 2] (a) is a schematic diagram of the light-emitting module in the display device according to the embodiment, viewed from the rear, and (b) is a diagram of the liquid crystal display element, each diffractive optical element, and each light source in the display device according to the embodiment, viewed from the rear. [Figure 3] (a) is a schematic plan view showing the positional relationship between the red light source, the red diffractive optical element, and the liquid crystal display device of the display device according to the embodiment, and (b) is a schematic plan view showing the positional relationship between the green light source and the blue light source, the green diffractive optical element and the blue diffractive optical element, and the liquid crystal display device of the display device according to the embodiment. [Figure 4] This is a schematic side view showing the display device according to the embodiment. [Figure 5] This is a schematic perspective view of the display device according to the embodiment. [Figure 6] (a) is a schematic side view of the red diffractive optical element in the display device according to the embodiment, and (b) is a schematic diagram showing the angular range of diffractive light irradiated from the exit surface of the red diffractive optical element to the incident surface of the liquid crystal display element in the display device according to the embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. As shown in Figure 1, the projection device 10 of this embodiment comprises a housing 12, a display device 20 provided inside the housing 12, and a projection optical system 16. The display device 20 comprises at least a light-emitting module 30 that emits multiple lights, three diffractive optical elements 40R, 40G, and 40B provided on the light-emitting side of the light-emitting module 30 to correspond to different emission wavelengths for the multiple lights emitted from the light-emitting module 30, and a liquid crystal display element (illuminated object) 50 provided on the light-emitting side of each diffractive optical element 40R, 40G, and 40B. The light-emitting module 30 has light sources 36R, 36G, and 36B.

[0011] The projection device 10 irradiates the liquid crystal display element 50 with each of the light emitted from the light-emitting module 30 via the diffractive optical elements 40R, 40G, and 40B, thereby forming a light image on the liquid crystal display element 50. The projection optical system 16 then projects the image onto a projection surface 90, such as a screen, by emitting it to the outside of the housing 12 (see the direction of the arrow in Figure 1). Inside the housing 12, a single heat sink 70 is provided to cool the multiple light sources 36R, 36G, and 36B of the light-emitting module 30, spanning across the multiple light sources 36R, 36G, and 36B. A single cooling fan 80 is also provided to cool the multiple light sources 36R, 36G, and 36B together. A control unit is provided to control and manage the electrical configuration of the multiple light sources 36R, 36G, and 36B of the projection device 10, the cooling fan 80, and other components. The surfaces of each light source 36R, 36G, and 36B that contact the heat sink 70 are arranged on substantially the same virtual plane. In this way, by arranging each light source 36R, 36G, and 36B in parallel on a virtual plane and arranging them so that the direction of light emission is approximately the same, it is not necessary to provide a heat sink 70 or cooling fan 80 for each light source. This simplifies the layout design, reduces the volume inside the housing 12, and allows for a downsizing of the entire projection device 10.

[0012] For convenience, as shown in Figure 1, the projection direction from the projection device 10 to the object to be projected onto 90 (the direction of the arrow in Figure 1) will be considered the front, and the opposite side will be considered the rear. Therefore, the direction from the light-emitting module 30 to the liquid crystal display element 50 will be approximately the front direction. Furthermore, the direction along the plane of Figure 1 that is perpendicular to the front-to-back direction will be considered the left-to-right direction (the right side when viewed from the rear to the front), and the direction perpendicular to both the front-to-back and left-to-right directions will be considered the up-to-down direction (the direction from the front to the back of the plane of Figure 1, and the direction from the back to the front).

[0013] As shown in Figures 1 and 2(a), the light-emitting module 30 is a so-called multi-chip package (MCM), and nine light sources (four red light sources 36R, three green light sources 36G, and two blue light sources 36B) that emit coherent light are provided in a light-emitting section 34 located approximately in the center of the light source substrate 32. The four red light sources 36R are semiconductor light-emitting elements that emit laser light in the red wavelength band (e.g., 640-770 nm) and are arranged in a single row at approximately equal intervals in the left-right direction on the upper side of the light-emitting section 34. The three green light sources 36G are semiconductor light-emitting elements that emit laser light in the green wavelength band (e.g., 490-550 nm) and are arranged in a single row at approximately equal intervals in the left-right direction on the lower left side of the light-emitting section 34. The two blue light sources 36B are semiconductor light-emitting elements that emit laser light in the blue wavelength band (e.g., 430-490 nm), and are arranged in parallel in the left-right direction in close proximity to each green light source 36G on the lower right side of the light-emitting section 34.

[0014] Each light source 36R, 36G, and 36B is positioned such that the optical axis direction of the emitted light is aligned with the front-to-back direction, and emits laser light forward. Hereafter, the front-to-back direction will also be referred to as the optical axis direction. Each light source 36R, 36G, and 36B is provided on the same plane in the light-emitting module 30. Furthermore, each green light source 36G and each blue light source 36B are positioned at the same height in the vertical direction. The light-emitting module 30 includes convex lenses provided on the front side of each light source 36R, 36G, and 36B, which is the light-emitting side. These convex lenses convert the laser beam emitted from each light source 36R, 36G, and 36B into parallel light parallel to the optical axis direction, and then incident on each diffractive optical element 40R, 40G, and 40B.

[0015] As described above, in the light-emitting module 30, multiple light-emitting points are generated even with light of the same wavelength band (light of the same color). Therefore, in this embodiment, for each of the four red light sources 36R, three green light sources 36G, and two blue light sources 36B, the center of the light intensity of the multiple light-emitting points, i.e., the centroid of the light intensity, is defined. Specifically, for each light source 36R, 36G, and 36B, the centroids of the light-emitting points are determined by assigning weights to them according to their irradiance, and this position is defined as the centroid of the light intensity.

[0016] For example, as shown in Figure 2(a), for the red light source 36R, the centroid of the light intensity is the position of the center of each of the four light-emitting points arranged in the left-right direction (hereinafter referred to as "red light intensity centroid RC"). For the green light source 36G, the centroid of the light intensity is the position of the center of each of the three light-emitting points arranged in the left-right direction (hereinafter referred to as "green light intensity centroid GC"). For the blue light source 36B, the centroid of the light intensity is the position of the center of each of the two light-emitting points arranged in the left-right direction (hereinafter referred to as "blue light intensity centroid BC"). In the following, the light emitted forward along the optical axis from the centroid RC of the red light source is defined as the principal ray of the luminous flux emitted from each of the four red light sources 36R, the light emitted forward along the optical axis from the centroid GC of the green light source is defined as the principal ray of the luminous flux emitted from each of the three green light sources 36G, and the light emitted forward along the optical axis from the centroid BC of the blue light source is defined as the principal ray of the luminous flux emitted from each of the two blue light sources 36B. Based on these principal rays, the diffraction angles of the light will be calculated.

[0017] Each of the folding optical elements 40R, 40G, and 40B is an optical element configured by stacking a plurality of substantially plate-shaped diffraction gratings with different grating intervals formed by fine concavo-convex structures, so that their functions are integrated as if they were a single element. Each of the folding optical elements 40R, 40G, and 40B includes a red folding optical element 40R disposed on the front side along the optical axis direction of each red light source 36R between each red light source 36R and the liquid crystal display element 50, a green folding optical element 40G disposed on the front side along the optical axis direction of each green light source 36G between each green light source 36G and the liquid crystal display element 50, and a blue folding optical element 40B disposed on the front side along the optical axis direction of each blue light source 36B between each blue light source 36B and the liquid crystal display element 50. Each of the folding optical elements 40R, 40G, and 40B diffracts the principal rays (laser light) of the light beams incident in parallel from each of the light sources 36R, 36G, and 36B and emits them toward the liquid crystal display element 50.

[0018] Each of the folding optical elements 40R, 40G, and 40B is arranged such that the surface directions of its incident surfaces 40R1, 40G1, and 40B1 and its exit surfaces 40R2, 40G2, and 40B2 are orthogonal to the optical axis direction. In other words, the normal directions of the incident surfaces 40R1, 40G1, and 40B1 and the normal directions of the exit surfaces 40R2, 40G2, and 40B2 are substantially parallel to the optical axis direction. Then, as shown in FIG. 2(b), the red folding optical element 40R is arranged such that the center position of its incident surface 40R1 overlaps with the red light quantity center of gravity RC in the optical axis direction, the green folding optical element 40G is arranged such that the center position of its incident surface 40G1 overlaps with the green light quantity center of gravity GC in the optical axis direction, and the blue folding optical element 40B is arranged such that the center position of its incident surface 40B1 overlaps with the blue light quantity center of gravity BC in the optical axis direction.

[0019] Furthermore, each diffractive optical element 40R, 40G, and 40B has its diffractive emission surfaces 40R2, 40G2, and 40B2 parallel to each other, and is arranged so that two of them are in the same position in the optical axis direction. Specifically, the green diffractive optical element 40G and the blue diffractive optical element 40B are arranged in parallel to each other, left and right, so that they are in the same position in the optical axis direction. In other words, the green diffractive optical element 40G and the blue diffractive optical element 40B are arranged on the same plane. The red diffractive optical element 40R is positioned offset along the optical axis direction from the green diffractive optical element 40G and the blue diffractive optical element 40B. In addition, the distance between the green diffractive optical element 40G and the blue diffractive optical element 40B and the liquid crystal display element 50 is set to be longer than the distance between the red diffractive optical element 40R and the liquid crystal display element 50.

[0020] In this embodiment, each diffractive optical element 40R, 40G, and 40B is manufactured based on substantially the same optical design and set to the same lattice spacing (pitch) P. For example, taking the red diffractive optical element 40R as an example, as shown in Figure 6(a), the lattice spacing P at the emission surface (diffractive surface) 40R2, that is, the distance P between the recesses 42a and protrusions 42b that constitute one lattice, is in the range of 1.5 to 5 μm. From the emission surface 40R2 of the red diffractive optical element 40R, light diffracted by the red diffractive optical element 40R (first-order light: m=±1) and light that is not diffracted (zero-order light: m=0) are emitted. Here, the diffraction angle θ of the light diffracted by each diffractive optical element 40R, 40G, and 40B is expressed by an approximate formula including λ / P, where λ (nm) is the wavelength of the laser light emitted from each light source 36R, 36G, and 36B. Each of the diffractive optical elements 40R, 40G, and 40B has the same lattice spacing P, but differs in its lattice pattern, including the depth of the recesses 42a, the height of the protrusions 42b, and the arrangement of the uneven structure. Each of the diffractive optical elements 40R, 40G, and 40B can be manufactured by known manufacturing methods such as photolithography.

[0021] In addition, in the present embodiment, a vibration device (vibration member) 60 configured by an electromagnetic method, a piezoelectric element, or the like is provided above each of the diffraction optical elements 40R, 40G, and 40B (see FIG. 5). Then, due to the minute vibrations of the diffraction optical elements 40R, 40G, and 40B in the vertical and horizontal directions by these vibration devices 60, as a result of the laser light emitted from each of the light sources 36R, 36G, and 36B passing through the diffraction optical elements 40R, 40G, and 40B, the generation of speckle noise is suppressed.

[0022] The liquid crystal display element 50 is a horizontally long substantially rectangular plate-shaped member having a long side and a short side, and its incident surface (irradiation surface) 50a, the incident possible region 50I, and the exit surface 50b are arranged so as to be parallel to the exit surfaces (diffraction surfaces) 40R2, 40G2, and 40B2 of the diffraction optical elements 40R, 40G, and 40B. A general liquid crystal display element 50 with high linearity and small diffusion is used. The liquid crystal display element 50 is configured to be applied with a voltage and can be switched between an on state in which a voltage is applied and an off state in which no voltage is applied by a control unit. Inside the liquid crystal display element 50, liquid crystal (not shown) is encapsulated in a predetermined alignment direction in the off state. When the voltage is applied to switch the liquid crystal display element 50 to the on state, the alignment direction of the internal liquid crystal is switched by 90°. In the liquid crystal display element 50, the switching between the on state and the off state is controlled by the control unit in a time-division manner.

[0023] The liquid crystal display element 50 is positioned such that its long side (hereinafter referred to as "long side 50L") is aligned in the left-right direction, and its short side (hereinafter referred to as "short side 50S") is aligned in the up-down direction. The incident surface 50a of the liquid crystal display element 50 has an incident area 50I with the upper left corner 50LU, the lower left corner 50LL, the upper right corner 50RU, and the lower right corner 50RL, which are configured to allow incident light to be appropriately emitted when viewed from the light sources 36R, 36G, and 36B. The liquid crystal display element 50 is positioned such that light diffracted by each diffractive optical element 40R, 40G, and 40B from the principal rays of the light beam emitted from each light source 36R, 36G, and 36B is incident on the incident surface 50a, while light not diffracted by each diffractive optical element 40R, 40G, and 40B is not incident on the incident surface 50a.

[0024] Specifically, as shown in Figures 2(b) and 4, the green light source 36G and the blue light source 36B are arranged so as to be aligned along the long side of the incident surface 50a, and the red light source 36R is positioned at a different location from the green light source 36G and the blue light source 36B in the short side of the incident surface 50a. Furthermore, the liquid crystal display element 50 is arranged such that the approximate center of the red diffractive optical element 40R (the position where it coincides with the centroid RC of the red light intensity) is shifted to the upper left (offset position) relative to the approximate center of the incident surface 50a of the liquid crystal display element 50, the approximate center of the green diffractive optical element 40G (the position where it coincides with the centroid GC of the green light intensity) is shifted to the lower right (offset position) relative to the approximate center of the incident surface 50a of the liquid crystal display element 50, and the approximate center of the blue diffractive optical element 40B (the position where it coincides with the centroid BC of the blue light intensity) is shifted to the lower left (offset position) relative to the approximate center of the incident surface 50a of the liquid crystal display element 50.

[0025] Next, with reference to Figures 3 to 5, the incidence and emission of light in each component constituting the display device 20 will be explained. The principal ray of the light beam emitted from each red light source 36R is incident on the incident surface 40R1 of the red diffractive optical element 40R. When the principal ray from the red light source 36R is incident on the red diffractive optical element 40R, diffracted light (first-order light) (hereinafter referred to as "red first-order light RL1") and undiffracted light (zero-order light) (hereinafter referred to as "red zero-order light RL0") are emitted from the emission surface 40R2 of the red diffractive optical element 40R. Of these, the red first-order light RL1 is diffracted toward the liquid crystal display element 50 side (lower right side) and incident on the incident surface 50a of the liquid crystal display element 50. On the other hand, the red zero-order light RL0 travels in a straight line along the optical axis, so it is not incident on the liquid crystal display element 50 and is not projected from the projection device 10 toward the object to be projected 90.

[0026] The principal ray of the light beam emitted from the green light source 36G is incident on the incident surface 40G1 of the green diffractive optical element 40G. When the principal ray from the green light source 36G is incident on the green diffractive optical element 40G, diffracted light (first-order light) (hereinafter referred to as "green first-order light GL1") and undiffracted light (zero-order light) (hereinafter referred to as "green zero-order light GL0") are emitted from the exit surface 40G2 of the green diffractive optical element 40G. Of these, the green first-order light GL1 is diffracted toward the liquid crystal display element 50 side (upper left side) and incident on the incident surface 50a of the liquid crystal display element 50. On the other hand, the green zero-order light GL0 travels in a straight line along the optical axis, so it is not incident on the liquid crystal display element 50 and is not projected from the projection device 10 toward the object to be projected 90.

[0027] The principal ray of the light beam emitted from the blue light source 36B is incident on the incident surface 40B1 of the blue diffractive optical element 40B. When the principal ray from the blue light source 36B is incident on the blue diffractive optical element 40B, diffracted light (primary light) (hereinafter referred to as "blue primary light BL1") and undiffracted light (zero-order light) (hereinafter referred to as "blue zero-order light BL0") are emitted from the exit surface 40B2 of the blue diffractive optical element 40B. Of these, the blue primary light BL1 is diffracted toward the liquid crystal display element 50 side (upper right side) and is incident on the incident surface 50a of the liquid crystal display element 50. On the other hand, the blue zero-order light BL0 travels in a straight line along the optical axis, so it is not incident on the liquid crystal display element 50 and is not projected from the projection device 10 toward the object to be projected 90. As described above, each diffractive optical element 40R, 40G, and 40B is positioned offset vertically and horizontally so that the red zero-order light, green zero-order light, and blue zero-order light do not overlap with the incident surface 50a of the liquid crystal display element 50 in the optical axis direction.

[0028] In this embodiment, if the green diffractive optical element 40G and the blue diffractive optical element 40B are not arranged on the same plane, and the green diffractive optical element 40G is positioned closer to the incident surface 50a of the liquid crystal display element 50 than the blue diffractive optical element 40B in the optical axis direction, a portion of the blue primary light BL1 may be incident on the incident surface 40G1 of the green diffractive optical element 40G, potentially causing interference. In contrast, in this embodiment, since the green diffractive optical element 40G and the blue diffractive optical element 40B are arranged on the same plane, such interference is prevented. Furthermore, in this embodiment, the green light sources 36G and the blue light sources 36B are arranged in close proximity in the light-emitting module 30, but for example, the red light sources 36R and the green light sources 36G may be arranged in close proximity, or the red light sources 36R and the blue light sources 36B may be arranged in close proximity. In this case, the arrangement of the diffractive optical elements 40R, 40G, and 40B can be adjusted to prevent the above-mentioned interference.

[0029] Here, since diffractive optical elements have the characteristic that the diffraction angle is larger the longer the wavelength of the incident light, when the lattice spacing P of each diffractive optical element 40R, 40G, and 40B is the same, as in this embodiment, the order of magnitude of the diffraction angles of the red primary light RL1 (hereinafter referred to as "red diffraction angle θR"), the green primary light GL1 (hereinafter referred to as "green diffraction angle θG"), and the blue primary light BL1 (hereinafter referred to as "blue diffraction angle θB") is red diffraction angle θR > green diffraction angle θG > blue diffraction angle θB. By making the red diffraction angle θR, green diffraction angle θG, and blue diffraction angle θB different in this way, it is possible to easily increase the diffraction efficiency of the red primary light RL1, green primary light GL1, and blue primary light BL1. Then, with this order of magnitude, the red primary light RL1, green primary light GL1, and blue primary light BL1 incident on the incident surface 50a of the liquid crystal display element 50 generate image light in the liquid crystal display element 50. This image light is emitted from the emission surface 50b of the liquid crystal display element 50, passes through the projection optical system 16, and is emitted to the outside of the projection device 10.

[0030] Next, referring to Figures 5 and 6(b), the minimum incident angle θmin and maximum incident angle θmax of the red primary light RL1, green primary light GL1, and blue primary light BL1 incident on the liquid crystal display element 50 will be described. Here, the light incident at the minimum incident angle θmin is defined as the minimum incident light Lmin, and the light incident at the maximum incident angle θmax is defined as the maximum incident light Lmax. As shown in Figure 6(b), for example, the angular range of the red diffraction angle θR (irradiation range α of the primary red light RL1) incident on the incident surface 50a of the liquid crystal display element 50 from the exit surface 40R2 of the red diffractive optical element 40R is such that the minimum incident angle θmin occurs when the primary red light RL1 is incident on the portion 50RCN closest to the centroid RC of the red light intensity, specifically on the line segment connecting the upper left corner 50LU and the upper right corner 50RU, within the incidentable region 50I of the incident surface 50a of the liquid crystal display element 50, where the distance from the centroid RC of the red light intensity is shortest. Conversely, the maximum incident angle θmax occurs when the primary red light RL1 is incident on the portion 50RCN closest to the centroid RC of the red light intensity, specifically on the lower right corner 50RL, within the incidentable region 50I, where the distance from the centroid RC of the red light intensity is longest.

[0031] Furthermore, the angular range of the green diffraction angle θG (irradiation range α of the green primary light GL1) is such that the minimum incidence angle θmin occurs when the green primary light GL1 is incident on the part 50GCN, which is the shortest distance from the green light centroid GC at the end of the incidentable region 50I on the lower long side surface 50L, specifically on the line segment connecting the lower left corner 50LL and the lower right corner 50RL of the incidentable region 50I, and is closest to the green light centroid GC. The maximum incidence angle θmax occurs when the green primary light GL1 is incident on the part of the upper long side surface 50L, specifically on the upper right corner 50RU of the incidentable region 50I, and is closest to the green light centroid GC. Furthermore, the angular range of the blue diffraction angle θB (irradiation range α of the blue primary light BL1) is such that the minimum incidence angle θmin occurs when the blue primary light BL1 is incident on the part 50BCN, which is the shortest distance from the blue light centroid BC at the end of the incidentable region 50I on the lower long side surface 50L of the incident surface 50a, specifically on the line segment connecting the lower left corner 50LL and the lower right corner 50RL of the incidentable region 50I, and is closest to the blue light centroid BC. The maximum incidence angle θmax occurs when the blue primary light BL1 is incident on the part of the upper long side surface 50L on the incidentable region 50I, specifically on the upper left corner 50LU of the incidentable region 50I, and is longest distance from the blue light centroid BC at the end of the incidentable region 50L.

[0032] At this time, the irradiation distance d from each diffractive optical element 40R, 40G, 40B to the incident surface 50a of the liquid crystal display element 50 can be calculated using an approximate formula that includes the minimum incident angle θmin, the maximum incident angle θmax, the length dimension in the long side direction of the incidentable region 50I of the incident surface 50a, and the length dimension in the short side direction of the incidentable region 50I of the incident surface 50a. Furthermore, the offset distance β of each diffractive optical element 40R, 40G, 40B with respect to the incident surface 50a of the liquid crystal display element 50 can be calculated using the calculated irradiation distance d and the formula that includes the minimum incident angle θmin. Then, the angle of the line connecting each diffractive optical element 40R, 40G, 40B and the center of the incident area 50I of the incident surface 50a of the liquid crystal display element 50, in other words, the angle of the center position of the minimum incident angle θmin and the maximum incident angle θmax (hereinafter referred to as "set incident angle θset"), can be calculated using an equation that includes the calculated offset distance β, the length dimension in the long side direction of the incident area 50I of the incident surface 50a, and the length dimension in the short side direction of the incident area 50I of the incident surface 50a. Here, the light incident at the set incident angle θset is called the set incident light Lset.

[0033] In this embodiment, the set incidence angle θset is set for the red primary light RL1, green primary light GL1, and blue primary light BL1 irradiated onto the incident surface 50a of the liquid crystal display element 50 so that the irradiation range of the red primary light RL1, green primary light GL1, and blue primary light BL1 is approximately equal to the incident area 50I. Based on the set incidence angle θset, the red diffraction angle θR, green diffraction angle θG, blue diffraction angle θB, and the arrangement of each diffractive optical element 40R, 40G, and 40B along the optical axis are set. In this way, the red primary light RL1, green primary light GL1, and blue primary light BL1 irradiate the incident area 50I of the incident surface 50a in overlapping manner, making the components of each color approximately equal. As a result, it is possible to prevent bias in any of the red, green, or blue colors in the image light generated by the liquid crystal display element 50, and to project a clear image onto the object to be projected.

[0034] As described above, the display device 20 according to this embodiment includes a light-emitting module 30 including a light-emitting section 34 in which a plurality of light sources 36R, 36G, and 36B emitting coherent light of different colors are arranged on the same plane; three diffractive optical elements 40R, 40G, and 40B are provided to correspond to different light emission colors for each light source 36R, 36G, and 36B, and the light from each light source 36R, 36G, and 36B is incident on and diffracted by them; and a liquid crystal display element 50 is irradiated with light diffracted by each diffractive optical element 40R, 40G, and 40B from the light emitted from each light source 36R, 36G, and 36B (red primary light RL1, green primary light GL1, and blue primary light BL1). Each diffractive optical element 40R, 40G, and 40B is positioned to irradiate the liquid crystal display element 50 with light of different diffraction angles depending on the color of the incident light.

[0035] As a result of the above-described configuration, the display device 20 of this embodiment is configured such that the primary red light RL1, primary green light GL1, and primary blue light BL1 emitted from each diffractive optical element 40R, 40G, and 40B irradiate the liquid crystal display element 50, while the zeroth-order red light RL0, zeroth-order green light GL0, and zeroth-order blue light BL0 emitted from each diffractive optical element 40R, 40G, and 40B do not irradiate the liquid crystal display element 50. Therefore, color unevenness in the image light generated by the liquid crystal display element 50 can be reduced. Furthermore, each diffractive optical element 40R, 40G, and 40B can be manufactured according to the same optical design, thereby reducing manufacturing costs.

[0036] Furthermore, in the display device 20 of this embodiment, by providing diffractive optical elements 40R, 40G, and 40B corresponding to different emission colors for each light source 36R, 36G, and 36B, the red primary light RL1, green primary light GL1, and blue primary light BL1 emitted from each diffractive optical element 40R, 40G, and 40B can be directly incident onto the liquid crystal display element 50 due to the difference in diffraction angles. Therefore, there is no need to arrange multiple components to guide the light emitted from the diffractive optical elements to the liquid crystal display element 50, and since each light source 36R, 36G, and 36B is integrated as a light-emitting module 30, the size of the display device 20 can be kept down compared to conventional configurations using diffractive optical elements. In addition, by arranging the red primary light RL1, green primary light GL1, and blue primary light BL1 with different diffraction angles in this way, the diffraction efficiency of the red primary light RL1, green primary light GL1, and blue primary light BL1 can be increased.

[0037] Furthermore, in the display device 20 of this embodiment, the liquid crystal display element 50 is positioned so that it is not irradiated with light that is not diffracted by the diffracting optical elements 40R, 40G, and 40B from the light emitted from each light source 36R, 36G, and 36B. This makes it possible to reduce color unevenness on the projection surface 90.

[0038] Furthermore, in the display device 20 of this embodiment, each diffractive optical element 40R, 40G, and 40B has equal grid spacing, and their diffracting surfaces, which are the emission surfaces 40R2, 40G2, and 40B2, are parallel to each other, and are arranged so that two of them are in the same position in the optical axis direction. With this configuration, by adjusting the position of each diffractive optical element 40R, 40G, and 40B along the optical axis direction according to the magnitude and relative size of the red diffraction angle θR, green diffraction angle θG, and blue diffraction angle θB, the irradiation size (irradiation range) of the red primary light RL1, green primary light GL1, and blue primary light BL1 irradiated from each diffractive optical element 40R, 40G, and 40B onto the liquid crystal display element 50 can be made approximately equal. As a result, it is possible to prevent bias in any of the red, green, or blue colors in the image light generated by the liquid crystal display element 50.

[0039] Furthermore, in the display device 20 of this embodiment, the light-emitting module 30 has green light sources 36G and blue light sources 36B of different emission colors arranged in close proximity, and the green diffractive optical elements 40G and blue diffractive optical elements 40B that correspond to the green light sources 36G and blue light sources 36B that are arranged in close proximity are arranged so that they are in the same position in the optical axis direction. With this configuration, it is possible to prevent the green primary light GL1 from being incident on the incident surface 40B1 of the blue diffractive optical element 40B, and the blue primary light BL1 from being incident on the incident surface 40G1 of the green diffractive optical element 40G. This prevents interference from occurring between the green primary light GL1 and the blue primary light BL1.

[0040] Furthermore, in the display device 20 of this embodiment, the light sources 36R, 36G, and 36B include a red light source 36R that emits red wavelength band light, a green light source 36G that emits green wavelength band light, and a blue light source 36B that emits blue wavelength band light. The lattice pattern of the diffraction grating of each diffractive optical element 40R, 40G, and 40B is set such that the diffraction angle (red diffraction angle θR) is largest when light from the red light source 30R is incident, and the diffraction angle (blue diffraction angle θB) is smallest when light from the blue light source 36B is incident. With this configuration, a display device 20 equipped with a red light source 36R, a green light source 36G, and a blue light source 36B can be realized. Here, if the lattice spacing P of each diffractive optical element 40R, 40G, and 40B is the same, the diffraction angle is larger the longer the wavelength of the incident light, so the relationship red diffraction angle θR > green diffraction angle θG > blue diffraction angle θB holds true. Therefore, the diffraction efficiency of each color, red, green, and blue, can be increased.

[0041] Furthermore, the display device 20 of this embodiment includes four red light sources 36R, three green light sources 36G, and two blue light sources 36B. Each diffractive optical element 40R, 40G, and 40B has a diffraction grating pattern set such that the red diffraction angle θR is largest when light emitted from the red light intensity centroid RC is incident, and the blue diffraction angle θB is smallest when light emitted from the blue light intensity centroid BC is incident. With this configuration, by defining the light intensity centroid for each light source 36R, 36G, and 36B with different wavelength bands, the diffraction angles θR, θG, and θB for each diffractive optical element 40R, 40G, and 40B when light emitted from each light intensity centroid RC, GC, and BC is incident can be approximated as the diffraction angles when light emitted from each light source 36R, 36G, and 36B is incident. Therefore, it is possible to realize a display device 20 that has multiple light-emitting modules 30 having light sources 36R, 36G, and 36B of the same wavelength band, while being able to improve the diffraction efficiency of each color, red, green, and blue.

[0042] Furthermore, in the display device 20 of this embodiment, the liquid crystal display element 50 includes a substantially rectangular incident surface 50a having a long side and a short side, with the short side arranged to follow the thickness direction of the display device 20. Of the red light source 36R, green light source 36G, and blue light source 36B, the green light source 36G and blue light source 36B are arranged to be aligned along the long side direction of the incident surface 50a, while the red light source 36R is positioned differently from the green light source 36G and blue light source 36B in the short side direction of the incident surface 50a. With this configuration, for example, among the light sources 36R, 36G, and 36B, the principal rays of the blue light source 36B, which has the smallest diffraction angle of primary light, and the principal rays of the green light source 36G, which has the next smallest diffraction angle of primary light, are arranged along the longer side, while the red light source 30R, which has the largest diffraction angle of primary light, is positioned in a different location from the blue light source 30B and the green light source 30G in the shorter side. This makes it easier to adjust the irradiation size (irradiation range) of the red primary light RL1, green primary light GL1, and blue primary light BL1 to be approximately equal.

[0043] Furthermore, in the display device 20 of this embodiment, each of the multiple diffractive optical elements 40R, 40G, and 40B is positioned offset along the incident surface 50a so that the red zero-order light RL0, green zero-order light GL0, and blue zero-order light BL0 do not overlap with the incident surface 50a in the optical axis direction. This makes it possible to realize a specific configuration in a display device equipped with a red light source 36R, a green light source 36G, a blue light source 36B, and a liquid crystal display element 50 having a substantially rectangular incident surface 50a, so that the red zero-order light RL0, green zero-order light GL0, and blue zero-order light BL0 are not incident on the incident surface 50a.

[0044] Furthermore, in the display device 20 of this embodiment, each light source 36R, 36G, and 36B is a light-emitting element that emits laser light, and is equipped with a vibration device 60 that vibrates each of the diffractive optical elements 40R, 40G, and 40B. With this configuration, the vibration device 60 vibrates each of the diffractive optical elements 40R, 40G, and 40B in the vertical and horizontal directions, thereby reducing the generation of speckle noise caused by the laser light.

[0045] The projection device 10 of this embodiment includes a liquid crystal display element 50 that generates image light as the object to be projected, a display device 20, and a projection optical system 16 that projects the image light generated by the liquid crystal display element 50 onto the object to be projected. This makes it possible to reduce the manufacturing cost of each diffractive optical element 40R, 40G, and 40B while preventing bias in any of the colors in the image light generated by the liquid crystal display element 50, thereby realizing a projection device 10 that can project a clear image onto the object to be projected.

[0046] The embodiments described above are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and essence of the invention, as well as in the claims of the invention and its equivalents.

[0047] For example, in each of the above embodiments, a liquid crystal display element was used as an example of the irradiated object, but the invention is not limited to this. For example, a DMD (Digital Micromirror Device) and a structure that forms an optical image with the reflected light of the DMD may be provided as the irradiated object, or a grating light bulb, light tunnel, microlens array, etc. may be provided. Also, in each of the above embodiments, a configuration in which no other members are placed between each diffractive optical element and the liquid crystal display element was used as an example, but a configuration in which lenses, reflective mirrors, dichroic mirrors, etc. are placed between each diffractive optical element and the liquid crystal display element is also possible. Furthermore, in each of the above embodiments, a configuration in which the pattern output from each diffractive optical element (the incident surface of the liquid crystal display element) is rectangular was used as an example, but a configuration in which a distorted rectangular shape is output by incidenting the liquid crystal display element from an oblique direction is also possible. [Explanation of Symbols]

[0048] 20: Display device, 30: Light-emitting module, 34: Light-emitting section, 36R: Red light source, 36G: Green light source, 36B: Blue light source, 40R: Red diffractive optical element, 40G: Green diffractive optical element, 40B: Blue diffractive optical element, 50: Liquid crystal display element, P: Grid spacing

Claims

1. A light-emitting module including a light-emitting section in which multiple light sources emitting coherent light of different colors are arranged on the same plane, A plurality of diffractive optical elements are provided to correspond to different emission colors for each of the plurality of light sources, and the light from the plurality of light sources is incident on and diffracted by them, The system comprises an irradiated object to which light diffracted by each of the diffractive optical elements from the light emitted from the plurality of light sources is irradiated, Each of the plurality of diffractive optical elements is positioned to irradiate the object to be irradiated with light of different diffraction angles depending on the color of the incident light, in an overlapping manner. Display device.

2. The irradiated object is positioned such that it is not irradiated by light emitted from the plurality of light sources that is not diffracted by the diffractive optical element. The display device according to claim 1.

3. Each of the plurality of diffractive optical elements has equal lattice spacings and parallel diffraction planes, and at least two are arranged to be in the same position in the direction along the optical axes of the plurality of light sources. The display device according to claim 1.

4. In the aforementioned light-emitting module, two types of light sources with different emission colors are arranged in close proximity. Of the plurality of diffractive optical elements, two corresponding to the two types of light sources that are arranged in close proximity are arranged to be in the same position in the direction along the optical axis of the plurality of light sources. The display device according to claim 1.

5. The light source includes a red light source that emits light in the red wavelength band, a green light source that emits light in the green wavelength band, and a blue light source that emits light in the blue wavelength band. Each of the plurality of diffractive optical elements is configured such that the diffraction angle is largest when light from the red light source is incident on it, and the diffraction angle is smallest when light from the blue light source is incident on it. The display device according to claim 1.

6. It includes a plurality of red light sources, a plurality of green light sources, and a plurality of blue light sources, Each of the plurality of diffractive optical elements is configured such that the diffraction angle is largest when light emitted from the centroidal position of the light intensity of the plurality of red light sources is incident on it, and the diffraction angle is smallest when light emitted from the centroidal position of the light intensity of the plurality of blue light sources is incident on it. The display device according to claim 5.

7. The irradiated object includes a substantially rectangular irradiation surface having a long side and a short side, with the direction of the short side aligned with the thickness direction of the display device. Of the red light source, the green light source, and the blue light source, any two are arranged so as to be aligned along the long side of the illumination surface, and the other one is positioned in a different location from the other two light sources in the short side of the illumination surface. The display device according to claim 5.

8. Each of the plurality of diffractive optical elements is positioned offset in a direction along the irradiation surface such that the light that is not diffracted does not overlap with the irradiation surface in the optical axis direction. The display device according to claim 7.

9. Each of the aforementioned plurality of light sources is a light-emitting element that emits laser light, The system includes a vibrating member that vibrates each of the plurality of diffractive optical elements. The display device according to claim 1.

10. The irradiated object is a display element that generates image light, A display device according to any one of claims 1 to 9, The system comprises a projection optical system that projects the image light generated by the display element onto an object to be projected onto. Projection device.

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