Projection device

Abstract

The projection device includes: a light source; a diffractive optical element on which light from the light source is incident; and a display element on which the light diffracted by the diffractive optical element is incident. The diffractive optical element projects the emitted light to the display element in a dot shape. The display element generates image light using at least a portion of the projected dot-shaped light.

Description

[0001] This application is based on Japanese Patent Application No. 2023-186505 filed on October 31, 2023. This specification refers to and includes the entirety of the specification, claims, and drawings of the basic application. Technical Field

[0002] The invention relates to a projection device. Background Art

[0003] Nowadays, projection devices are used that project a screen of a personal computer, a video screen, image data stored in a memory card, etc. onto a screen. Among such projection devices, there is known a device that diffracts light emitted from a light source by a diffractive optical element to display an image on a screen. For example, Japanese Patent Publication No. 2023-43061 discloses a projection device that includes a light source, a diffractive optical element that diffracts a laser beam emitted from the light source in a two-dimensional direction, and a lens that causes a parallel laser beam emitted from the diffractive optical element to enter and emits a convergent light. Summary of the invention

[0004] A projection device according to one embodiment of the present disclosure comprises: a light source; a diffractive optical element onto which light from the light source is incident; and a display element onto which the light diffracted by the diffractive optical element is incident; the diffractive optical element projects the emitted light in a point shape onto the display element; and the display element generates image light using at least a portion of the projected point-shaped light. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1A 1 is a schematic plan view showing a schematic diagram of a projection device according to a first embodiment. Figure 1B It is a schematic plan view showing the emission state of light emitted from the projection device according to the first embodiment.

[0006] Figure 2A is a front view schematic diagram showing the distribution of diffracted light projected onto a liquid crystal display element, Figure 2B is a front view schematic diagram showing a light-transmitting area and a light-shielding area of ​​a liquid crystal display element, Figure 2C It is a schematic front view showing image light projected onto a screen.

[0007] Figure 3 It is a schematic plan view showing the emission state of light emitted from the projection device according to the second embodiment.

[0008] Figure 4 It is a schematic diagram showing the outline of a diffractive optical element driving unit.

[0009] Figure 5 It is a schematic plan view showing the emission state of light emitted from the projection device according to the third embodiment.

[0010] Figure 6 It is a schematic plan view showing the emission state of light emitted from the projection device according to the fourth embodiment.

[0011] Figure 7 It is a schematic plan view showing a blue incident area of ​​a diffractive optical element in a projection device according to a fourth embodiment. DETAILED DESCRIPTION

[0012] (First embodiment)

[0013] 1 and Figure 2A to Figure 2C A first embodiment of the present disclosure will be described. Figure 1A The projection device 10 shown in the figure has a housing (not shown), and inside the housing is provided with a light emitting element (light source) 22, a diffractive optical element (Diffractive Optical Element) 30, and a liquid crystal display element (display element) 40. An opening, i.e., a projection port 10a, through which light from the light emitting element 22 is emitted to the outside of the housing is provided on the outer wall of the housing of the projection device 10. The light emitting element 22, the diffractive optical element 30, the liquid crystal display element 40, and the projection port 10a are arranged in sequence along Figure 1A The axes A shown are arranged on the same straight line.

[0014] The projection device 10 projects the image onto a projection object such as a screen (not shown) by irradiating the light beam emitted from the light emitting element 22 to the liquid crystal display element 40 via the diffractive optical element 30, forming a light image by the liquid crystal display element 40. In addition, although not shown, various components of a known projection device such as a heat sink and a cooling fan, and a control unit for overall control of the electrical structure of the projection device 10 are provided inside the housing. In addition, the following description is made with the projection port 10a side as the front side, the direction along the axis A as the front-rear direction of the projection device 10, and the left-right direction relative to the projection direction from the projection port 10a to the projection object as the left-right direction of the projection device 10.

[0015] The light emitting element 22 is a laser light source and is composed of a semiconductor light emitting element such as a laser diode. The light emitting element 22 is provided on the light source substrate 20 and emits a linear laser beam L1 (see Figure 1B ).like Figure 1B As shown, the laser light L1 emitted from the light emitting element 22 is emitted in a form in which the optical axis thereof is along the axis A.

[0016] The diffraction optical element 30 is an optical element formed by stacking a plurality of roughly plate-shaped diffraction gratings with different intervals of gratings composed of fine concavo-convex structures, and is arranged in a manner such that its incident surface and emission surface are orthogonal to the axis A. The diffraction optical element 30 diffracts the laser light L1 incident in parallel from the light emitting element 22 into a plurality of lights, and emits them toward the liquid crystal display element 40. In addition, the diffraction optical element 30 diffracts the incident laser light L1 and emits it so that it is projected in a point shape toward the liquid crystal display element 40 (hereinafter, the light emitted from the diffraction optical element 30 and projected onto the liquid crystal display element 40 is referred to as "diffracted light L2".).

[0017] That is, Figure 2A As shown, the laser light L1 incident on the diffractive optical element 30 is diffracted to branch into a plurality of beams, which are emitted from the diffractive optical element 30 as diffraction light L2 and projected onto the liquid crystal display element 40 in a point shape (hereinafter, the point-shaped bright spot projected onto the liquid crystal display element 40 is referred to as "point-shaped light DL"). The number of point-shaped lights DL projected onto the liquid crystal display element increases or decreases in accordance with the number of diffraction gratings constituting the diffractive optical element 30. In addition, in practice, a structure is used in which the functions obtained by superimposing a plurality of diffraction gratings are integrated into one piece.

[0018] The liquid crystal display element 40 is a roughly plate-shaped component, and is configured in a manner that its incident surface and emitting surface are orthogonal to the axis A. The liquid crystal display element 40 adopts a common structure with high linearity and small diffusion. A voltage is applied to the liquid crystal display element 40, and the control unit switches between an on state in which a voltage is applied and an off state in which no voltage is applied. Inside the liquid crystal display element 40, a liquid crystal (not shown) is sealed in a prescribed orientation direction in the off state. The liquid crystal display element 40 is switched to an on state by applying a voltage, so that the orientation direction of the liquid crystal inside is switched by 90°. In the liquid crystal display element 40, the switching between the on state and the off state is controlled by the control unit in a time-sharing manner.

[0019] By controlling the orientation direction of the liquid crystal in this way, the polarization direction of the diffracted light L2 passing through the liquid crystal display element 40 is switched by 90°. Figure 2B As shown in FIG. 4 , the liquid crystal display element 40 is divided into a light-transmitting area 40 a through which the diffracted light L2 passes and a light-shielding area 40 b through which the diffracted light L2 is blocked. Figure 2B, an example in which an upward arrow-shaped pattern is divided into light-transmitting areas 40a is shown. In the liquid crystal display element 40, the control unit divides the portion corresponding to an arbitrary pattern into the light-transmitting area 40a. Among the diffracted light L2 projected in a point shape on the liquid crystal display element 40, the diffracted light L2 projected in the light-transmitting area 40a passes through the liquid crystal display element 40, and the diffracted light L2 projected in the light-shielding area 40b is shielded (hereinafter, the diffracted light L2 after passing through the liquid crystal display element 40 is referred to as "image light L3"). In other words, the liquid crystal display element 40 generates the image light L3 using a part of the point-shaped diffracted light L2.

[0020] The image light L3 generated by the liquid crystal display element 40 is directly emitted from the projection port 10a to the outside of the box, and is projected onto a projection object such as a screen. Figure 2C As shown in FIG. 1 , the projection light PL projected onto the projection object is displayed as a collection of point-shaped lights by an upward arrow-shaped pattern similar to the pattern divided in the liquid crystal display element 40. That is, for the projection light PL projected onto the projection object, only the upward arrow-shaped pattern corresponding to the light-transmitting area 40a is displayed as the display area PL1, and the other parts become the non-display area PL2 that is not displayed (in addition, in FIG. Figure 2C In the figure, the non-display area PL2 is represented by lighter dots).

[0021] Since the projection light PL is generated from the laser L1, even if the distance between the diffractive optical element 30 and the object being projected changes, the size and number of points constituting the projection light PL will not change. Therefore, regardless of the distance between the diffractive optical element 30 and the object being projected, the projection light PL projected on the object being projected can be focused, and the number of pixels is constant. In addition, compared to the size of the point light DL projected from the diffractive optical element 30 on the liquid crystal display element 40, the size of the pixel of the liquid crystal display element 40 is made sufficiently small (for example, less than 1 / 5), thereby reducing the interference fringes caused by the point light DL. In addition, by adding the emitted polarized light from the light emitting element 22 and the incident polarized light of the liquid crystal display element 40, the transmission loss of the liquid crystal display element 40 is reduced.

[0022] As described above, the projection device 10 of this embodiment includes: a light emitting element 22; a diffraction optical element 30, to which the laser light L1 from the light emitting element 22 is incident; and a liquid crystal display element 40, to which the diffraction light L2 diffracted by the diffraction optical element 30 is incident; the diffraction optical element 30 projects the emitted diffraction light L2 in a point shape toward the liquid crystal display element 40; and the liquid crystal display element 40 generates image light L3 using a portion of the point light projected from the diffraction optical element 30.

[0023] The projection device 10 of this embodiment projects the diffracted light L2 from the diffractive optical element 30 onto the liquid crystal display element 40 in a dot shape as described above, and the diffracted light L2 passes through the light-transmitting area 40a divided into an arbitrary pattern in the liquid crystal display element 40 to generate the image light L3, and the image light L3 reaches the projection object, and the image of the pattern divided in the liquid crystal display element 40 is projected onto the projection object. In the past, in the projection device, the lens generates a plurality of bright spots arranged in a specific direction on the projection surface through a plurality of laser beams diffracted by the diffractive optical element, and projects a linear pattern extending along the specific direction onto the projection surface. Therefore, in order to change the pattern projected onto the projection surface to another pattern, it is necessary to replace the lens and other components with components corresponding to other patterns. In this embodiment, by controlling the orientation direction of the liquid crystal of the liquid crystal display element 40, an arbitrary pattern can be projected onto the projection object. In this way, the projection device 10 of this embodiment can change the projected pattern without replacing components.

[0024] Furthermore, the projection device 10 of the present embodiment includes the liquid crystal display element 40 as a display element. Therefore, an arbitrary pattern can be projected onto a projection object simply by controlling the alignment direction of the liquid crystal of the liquid crystal display element 40.

[0025] In addition, the projection device 10 of the present embodiment is provided with a projection port 10a for projecting the image light L3 generated by the liquid crystal display element 40 onto the projection object, and the image light L3 generated by the liquid crystal display element 40 is directly projected from the projection port 10a onto the projection object. As described above, regardless of the distance between the diffractive optical element 30 and the projection object, the projection light PL projected onto the projection object can be focused, so it is not necessary to set a lens component or the like between the liquid crystal display element 40 and the projection port 10a, and the projection device 10 can be miniaturized and cost-effective. In addition, since it is not necessary to set a lens component or the like between the liquid crystal display element 40 and the projection port 10a, it is not necessary to make the diffracted light L2 incident perpendicularly to the liquid crystal display element 40. Therefore, it is not necessary to set a lens component or the like between the diffractive optical element 30 and the liquid crystal display element 40, and the diffracted light L2 from the diffractive optical element 30 is directly incident on the liquid crystal display element 40. Thus, it is possible to miniaturize and cost-effectively the projection device 10.

[0026] In the projection device 10 of the present embodiment, the light emitting element 22 is a laser light source. By using a laser light source in this way, the diffracted light L2 diffracted by the diffractive optical element 30 can be projected in a dot shape onto the liquid crystal display element.

[0027] (Second embodiment)

[0028] Next, refer to Figure 3 and Figure 4The second embodiment of the present disclosure is described. Figure 3 As shown in FIG. 1 , the projection device 110 of the second embodiment includes a blue light emitting element (first light source) 122B, a red light emitting element (second light source) 122R, and a green light emitting element (third light source) 122G as light sources. In addition, the projection device 110 includes two dichroic mirrors (first dichroic mirror, second dichroic mirror) 150a, 150b, a diffractive optical element 130, and a liquid crystal display element 140. In addition, a projection port is provided on the housing of the projection device 110 as in the first embodiment, but Figure 3 Illustration omitted.

[0029] The blue light emitting element 122B is a laser light source provided on the blue light source substrate 120B, and is composed of a semiconductor light emitting element such as a laser diode, and emits a blue laser light L4B as a blue band light (first band light). The red light emitting element 122R is a laser light source provided on the red light source substrate 120R, and is composed of a semiconductor light emitting element such as a laser diode, and emits a red laser light L4R as a red band light (second band light). The green light emitting element 122G is a laser light source provided on the green light source substrate 120G, and is composed of a semiconductor light emitting element such as a laser diode, and emits a green laser light L4G as a green band light (third band light).

[0030] The green light emitting element 122G is arranged in such a configuration that the optical axis of the emitted green laser L4G is along the axis A (X direction). The blue light emitting element 122B is arranged in such a configuration that the optical axis of the emitted blue laser L4B is orthogonal to the axis A. The red light emitting element 122R is arranged in such a configuration that the optical axis of the emitted red laser L4R is orthogonal to the axis A and its emission surface is opposite to the blue light emitting element 122B. That is, the blue light emitting element 122B and the red light emitting element 122R are arranged to face each other in the Y direction orthogonal to the X direction. In the projection device 110 of this embodiment, the emission timing of the light from each light emitting element 122B, 122R, and 122G is controlled by the control unit. The emission timing of the light from each light emitting element 122B, 122R, and 122G can be arbitrarily set by the user according to the projected image (the pattern divided in the liquid crystal display element 40). For example, when an image indicating that passage is permitted is to be projected, green laser light L4G may be emitted, and when an image indicating that passage is prohibited is to be projected, red laser light L4R may be emitted.

[0031] The two dichroic mirrors 150a and 150b are arranged so that their respective parts overlap and intersect each other orthogonally from the Z direction orthogonal to the X direction and the Y direction, and are arranged at positions opposite to the respective emission surfaces of the blue light emitting element 122B, the red light emitting element 122R, and the green light emitting element 122G. Among them, the dichroic mirror 150b on one side transmits the red band light and the green band light, and reflects the blue band light. The dichroic mirror 150a on the other side transmits the blue band light and the green band light, and reflects the red band light. The diffractive optical element 130 has the same structure as the diffractive optical element 30 of the first embodiment, and is arranged on the emission surface side of the green light emitting element 122G in a manner that its incident surface and the emission surface are orthogonal to the axis A.

[0032] In the projection device 110, the blue laser light L4B emitted from the blue light emitting element 122B is reflected by the dichroic mirror 150b on one side in the direction in which its optical axis is along the axis line A, and is incident on the diffractive optical element 130. The red laser light L4R emitted from the red light emitting element 122R is reflected by the dichroic mirror 150a on the other side in the direction in which its optical axis is along the axis line A, and is incident on the diffractive optical element 130. The green laser light L4G emitted from the green light emitting element 122G is incident on the diffractive optical element 130 after passing through the two dichroic mirrors.

[0033] The diffraction optical element 130 diffracts the incident blue laser L4B, red laser L4R, and green laser L4G into a plurality of light beams in a manner of projecting them in a point shape toward the liquid crystal display element 140, and emits them toward the liquid crystal display element 140 (hereinafter, among the diffraction light beams emitted from the diffraction optical element 130 and projected toward the liquid crystal display element 140, the diffraction light beams based on the blue laser L4B are referred to as "blue diffraction light L5B", the diffraction light beams based on the red laser L4R are referred to as "red diffraction light L5R", and the light beams based on the green laser L4G are referred to as "green diffraction light L5G".). In addition, since the wavelengths of the laser beams L4B, L4R, and L4G are different from each other, as shown in FIG. Figure 3 As shown, the diffusion angles of the blue diffraction light L5B, the red diffraction light L5R, and the green diffraction light L5G toward the liquid crystal display element 140 are different, and increase in the order of the red diffraction light L5R, the green diffraction light L5G, and the blue diffraction light L5B.

[0034] The liquid crystal display element 140 has the same structure as the liquid crystal display element 40 of the first embodiment, and is arranged on the emission surface side of the diffractive optical element 130 in such a manner that its incident surface and emission surface are orthogonal to the axis A. Among the diffracted light L2 projected in a point shape on the liquid crystal display element 140, the light that passes through the light-transmitting area of ​​the liquid crystal display element 140 is emitted from the projection port of the box as image light and is projected onto the screen SC (hereinafter, among the image light, the image light based on the blue diffracted light L5B is referred to as "blue image light L6B", the image light based on the red diffracted light L5R is referred to as "red image light L6R", and the image light based on the green diffracted light L5G is referred to as "green image light L6G".).

[0035] On the screen SC, patterns of colors corresponding to the wavelength bands of the light emitting elements 122B, 122R, and 122G are projected corresponding to the patterns divided in the liquid crystal display element 140. That is, when the blue laser light L4B is emitted from the blue light emitting element 122B, a blue pattern is projected on the screen SC, when the red laser light L4R is emitted from the red light emitting element 122R, a red pattern is projected on the screen SC, and when the green laser light L4G is emitted from the green light emitting element 122G, a green pattern is projected on the screen SC.

[0036] Here, the projection device 110 of this embodiment has a diffractive optical element driving unit (moving mechanism) 160 that moves the diffractive optical element 130 on the axis A between the dichroic mirrors 150a, 150b and the liquid crystal display element 140, in other words, moves the diffractive optical element 130 in the front-to-back direction on the optical path of each laser L4B, L4R, L4G emitted from each light emitting element 122B, 122R, 122G.

[0037] like Figure 4 As shown, the diffractive optical element driving unit 160 includes a pair of sliders 160a1, 160a2, a pair of slide guides 160b1, 160b2, a motor 160c and a screw 160d. The sliders 160a1, 160a2 are arranged on the left and right sides of the diffractive optical element 130, and are guided by the slide guides 160b1, 160b2 to move freely in the front-back direction. The screw 160d is inserted through the slider 160a1 on one side. A ball screw structure is provided between the slider 160a1 and the screw 160d. The motor 160c is driven and controlled by the control unit of the projection device 110.

[0038] When the motor 160c rotates and the screw 160d rotates, the slider 160a1 moves forward and backward along the slide guide 160b1 together with the diffractive optical element 130. On the diffractive optical element 130, a slider 160a2 on the other side is installed opposite to the slider 160a1 on one side. The slider 160a2 is guided in the front-back direction by the slide guide 160b2. Therefore, the diffractive optical element 130 is displaced in the front-back direction by the slider 160a1 and is precisely guided in the front-back direction by the slider 160a2.

[0039] The diffractive optical element driving unit 160 is controlled by the control unit to move the diffractive optical element 130 in order to change the focusing position of each diffracted light L5B, L5R, and L5G emitted from the diffractive optical element 130 to the liquid crystal display element 140. Figure 4 In addition to the structure using a ball screw as shown, for example, the diffraction optical element 130 can also be fixed to a sliding guide portion that moves straight along a guide rail, and the sliding guide portion can be moved in the front-to-rear direction by driving the sliding guide portion with a linear guide portion or the like or using an actuator structure such as a piezoelectric element.

[0040] In the projection device 110 of the present embodiment, the diffractive optical element driving unit 160 controls the diffractive optical element 130 to move in the front-rear direction according to the diffusion angle of each diffracted light L5B, L5R, and L5G toward the liquid crystal display element 140, so that the size of the pattern projected on the screen SC is equal among the blue image light L6B, the red image light L6R, and the green image light L6G. For example, Figure 3 As shown, when the blue image light L6B is projected on the screen SC, the diffraction optical element 130 is moved to a position P1 away from the liquid crystal display element 140 and the blue laser L4B is incident. When the green image light L6G is projected, the diffraction optical element 130 is moved to a position P2 slightly away from the liquid crystal display element 140 and the green laser L4G is incident. When the red image light L6R is projected, the diffraction optical element 130 is moved to a position P3 close to the liquid crystal display element 140 and the red laser L4R is incident.

[0041] As described above, the projection device 110 of this embodiment includes, as light emitting elements, a blue light emitting element 122B emitting blue wavelength band light, a red light emitting element 122R emitting red wavelength band light, and a green light emitting element 122G emitting green wavelength band light. Thus, a blue pattern, a red pattern, and a green pattern can be projected onto the screen SC, respectively.

[0042] In addition, the projection device 110 of the present embodiment includes a diffractive optical element driving unit 160 that moves the diffractive optical element 130 on the optical path of the light from each light emitting element 122B, 122R, 122G, and the blue laser light L4B from the blue light emitting element 122B, the red laser light L4R from the red light emitting element 122R, and the green laser light L4G from the green light emitting element 122G are incident on the diffractive optical element 130 at different positions P1, P2, and P3, respectively. According to this structure, by changing the position of the diffractive optical element 130 in accordance with the diffusion angle of each diffracted light L5B, L5R, and L5G incident from the diffractive optical element 130 to the liquid crystal display element 140, the size (projection range) of each image light L6B, L6R, and L6G projected onto the screen SC can be made equal.

[0043] In addition, as a first variation of the present embodiment, the diffraction optical element 130 is not moved in the front-to-back direction, and the size of the pattern divided in the liquid crystal display element 140 is changed corresponding to the diffusion angle of each diffraction light L5B, L5R, L5G incident from the diffraction optical element 130 to the liquid crystal display element 140, thereby making it possible to make the sizes (projection ranges) of each image light L6B, L6R, L6G projected onto the screen SC equal.

[0044] In addition, as a second modification of the present embodiment, three diffractive optical elements 130 are arranged at intervals in the front-back direction on the axis A, and control is performed so that each laser light L4B, L4R, L4G is emitted from each light emitting element 122B, 122R, 122G at the same time, so that each laser light L4B, L4R, L4G is incident on a different diffractive optical element 330, thereby enabling the pattern to be projected on the screen SC in a full-color display mode. In this case, by setting the intervals between each diffractive optical element 130 to a small distance (for example, 1 mm), the influence of the different sizes (projection ranges) of each diffracted light L5B, L5R, L5G projected onto the liquid crystal display element 140 due to the difference in the diffusion angle of each diffracted light L5B, L5R, L5G can be reduced, and the influence of the resolution of each color (that is, the number of points of each diffracted light L5B, L5R, L5G used in the display area PL1) associated therewith can be reduced. The emission timing of light from each of the light emitting elements 122B, 122R, and 122G can be controlled in real time by the control section.

[0045] (Third embodiment)

[0046] Next, refer to Figure 5 The third embodiment of the present disclosure is described. Figure 5As shown, the projection device 210 of the third embodiment is different from the projection device 110 of the second embodiment in that a portion of the liquid crystal display element 240 is covered with a mask M and that the diffractive optical element driving unit is not provided. The other structures are the same as those of the second embodiment, so the description thereof is omitted. Figure 5 In, yes Figure 3 Each reference numeral shown in the figure with the number 100 added thereto is the same member as the member described in the second embodiment. Figure 5 In the figure, reference numerals L7B, L7R, and L7G represent blue laser, red laser, and green laser, respectively; reference numerals L8B, L8R, and L8G represent blue diffracted light, red diffracted light, and green diffracted light, respectively; and reference numeral L9B represents blue image light.

[0047] In the projection device 210 of the third embodiment, the position of the diffractive optical element 230 is fixed on the axis A between the two dichroic mirrors 250a, 250b and the liquid crystal display element 240. In addition, in the liquid crystal display element 240, the portion outside the range where the blue diffraction light L8B having the smallest diffusion angle among the diffraction lights L8B, L8R, and L8G emitted from the diffraction optical element 230 is projected is covered by a mask M. Therefore, among the red diffraction light L8R and the green diffraction light L8G emitted from the diffraction optical element 230 to the liquid crystal display element 240, only the light within the same range as the diffusion angle of the blue diffraction light L8B is projected onto the liquid crystal display element 240 in a dot shape, and the other light outside the range is blocked by the mask M.

[0048] In the projection device 210 of the present embodiment configured as such, within the same range as the diffusion angle of the blue diffracted light L8B, the blue image light L9B, a part of the red diffracted light L8R, and a part of the green diffracted light L8G can be projected onto the screen SC. Therefore, although a part of the red diffracted light L8R and the green diffracted light L8G is blocked by the mask M and some light loss occurs, the blue pattern, the red pattern, and the green pattern can be projected onto the prescribed range of the screen SC without providing a diffractive optical element moving part. In the present embodiment, the pattern can also be projected onto the screen SC in a full-color display. In this case, by positioning the liquid crystal display element 240 close to the diffractive optical element 230 or adjusting the grating interval (interval between the concave and convex parts) of the diffractive optical element 230 so as to reduce the difference in the diffusion angle of each diffracted light L8B, L8R, L8G, it is possible to reduce the influence of the resolution of each color (i.e., the number of points of each diffracted light L8B, L8R, L8G irradiated to the portion of the liquid crystal display element 240 not covered by the mask M). The emission timing of the light from each light emitting element 222B, 222R, 222G can be controlled in time by the control part.

[0049] (Fourth embodiment)

[0050] Next, refer to Figure 6 and Figure 7 , the fourth embodiment of the present disclosure is described. Figure 6 As shown, the projection device 310 of the fourth embodiment is different from the projection device 110 of the second embodiment in the irradiation positions of the blue laser L10B and the red laser L10R for the two dichroic mirrors 350a and 350b, the structure of the diffractive optical element 330, and the lack of a diffractive optical element driving unit. The other structures are the same as those of the second embodiment, so their description is omitted. Figure 6 In Figure 3 The reference numerals shown in the figure with the number 200 added thereto are the same components as those described in the second embodiment except for the diffractive optical element 330. Figure 6 In the figure, reference numerals L10B, L10R, and L10G represent blue laser, red laser, and green laser, respectively; reference numerals L11B, L11R, and L11G represent blue diffracted light, red diffracted light, and green diffracted light, respectively; and reference numerals L12B, L12R, and L12G represent blue image light, red image light, and green image light, respectively.

[0051] In the projection device 310 of the fourth embodiment, the diffractive optical element 330 is divided into three regions, namely, a blue incident region (first region) 330B into which the blue laser light L10B is incident, a red incident region (second region) 330R into which the red laser light L10R is incident, and a green incident region (third region) 330G into which the green laser light L10G is incident. In other words, in the diffractive optical element 330, each of the incident regions 330B, 330R, and 330G is arranged on the same plane. Each of the incident regions 330B, 330R, and 330G is divided roughly equally along the left-right direction in the diffractive optical element 330, the left side portion of the diffractive optical element 330 is set as the blue incident region 330B, the right side portion of the diffractive optical element 330 is set as the red incident region 330R, and the portion between the blue incident region 330B and the red incident region 330R is set as the green incident region 330G.

[0052] In addition, in the present embodiment, the blue laser light L10B is irradiated at a position of the dichroic mirror 350b on one side that is offset from the position where the two dichroic mirrors 350a and 350b overlap and is reflected toward the blue incident region 330B, so that the blue laser light L10B emitted from the blue light emitting element 322B is incident on the blue incident region 330B. In addition, the red laser light L10R is irradiated at a position of the dichroic mirror 350a on the other side that is offset from the position where the two dichroic mirrors 350a and 350b overlap and is reflected toward the red incident region 330R, so that the red laser light L10R emitted from the red light emitting element 322R is incident on the red incident region 330R.

[0053] In addition, in the diffractive optical element 330 of the present embodiment, the grating intervals of the diffraction gratings are different between the blue incident area 330B, the red incident area 330R, and the green incident area 330G. Specifically, the grating intervals of the incident areas 330B, 330R, and 330G of the diffractive optical element 330 are set corresponding to the wavelengths (wavelength bands) of the lasers L10B, L10R, and L10G, so that the diffusion angles of the diffracted lights L11B, L11R, and L11G toward the liquid crystal display element 340 are substantially equal to each other. As an example, Figure 7 As shown in FIG. 1 , when the diffusion angle θ of each diffracted light L11B, L11R, and L11G from the diffractive optical element 330 is set to 15.0 degrees, the grating interval in the blue incident area 330B, that is, the interval P between the concave portion 330a and the convex portion 330b constituting one grating is set to 30.7 nm. Here, when the wavelength of each laser light L10B, L10R, and L10G is λ (nm), the diffusion angle θ is calculated by the formula of λ / P.

[0054] In this way, by making the grating intervals of the incident regions 330B, 330R, and 330G of the diffractive optical element 330 different according to the wavelengths of the laser beams L10B, L10R, and L10G, the diffusion angles θ of the blue diffracted light L11B (blue pixel light L12B), the red diffracted light L11R (red pixel light L12R), and the green diffracted light L11G (green pixel light L12G) emitted from the incident regions 330B, 330R, and 330G can be made substantially equal to each other. Therefore, the sizes of the pixel lights L12B, L12R, and L12G projected onto the screen SC can be made equal without moving the diffractive optical element 330 in accordance with the laser beams L10B, L10R, and L10G.

[0055] In addition, in this embodiment, since there is no need to move the diffraction optical element 330 as described above, by controlling the simultaneous emission of each laser L10B, L10R, L10G from each light emitting element 322B, 322R, 322G, a pattern can be projected on the screen SC in full color, for example, a white pattern can be displayed on the screen SC.

[0056] In addition, when projecting in full color, in order to reduce the slight deviation of the projection position on the screen SC caused by the difference in the configuration of the incident areas 330B, 330R, and 330G in the diffraction optical element 330, it is preferred to set an inclination on the emission surface side of the concave-convex structure of the diffraction grating in the blue incident area 330B and the red incident area 330R, or adjust the configuration of the blue light emitting element 322B and the red light emitting element 322R, the overlapping angle of the two dichroic mirrors 350a and 350b, etc., so that the blue diffracted light L11B and the red diffracted light L11R are diffracted inward (on the green incident area 330G side) in a manner that the diffusion angle θ of the blue diffracted light L11B and the red diffracted light L11R is consistent with the diffusion angle θ of the green diffracted light L11G. In addition, by narrowing the interval between the lasers L10B, L10R, L10G incident on the diffractive optical element 330 (i.e., the interval between the incident areas 330B, 330R, 330G) (for example, to less than 1 mm), the point-shaped offset of the diffracted lights L11B, L11R, L11G incident on the liquid crystal display element 340 can be reduced.

[0057] As described above, in the projection device 310 of the present embodiment, the diffraction optical element 330 is provided with a blue incident area 330B on which light from the blue light emitting element 322B is incident, a red incident area 330R on which light from the red light emitting element 322R is incident, and a green incident area 330G on which light from the green light emitting element 322G is incident on the same plane, and the grating intervals of the diffraction gratings of the blue incident area 330B, the red incident area 330R, and the green incident area 330G are different from each other corresponding to the wavelength band of the incident light. According to this structure, by making the grating intervals of the diffraction gratings in each incident area 330B, 330R, and 330G different so that the diffusion angles of each diffracted light L11B, L11R, and L11G toward the liquid crystal display element 140 are approximately equal, the diffusion angles of the diffracted light L11B, L11R, and L11G can be made approximately equal, and full-color display can be achieved without separately providing a mechanism for moving the diffraction optical element 330.

[0058] In addition, in the projection device 310 of the present embodiment, the blue incident area 330B, the red incident area 330R, and the green incident area 330G diffract light so that the projection ranges of the diffracted lights L11B, L11R, and L11G emitted from the blue incident area 330B, the red incident area 330R, and the green incident area 330G and projected onto the screen SC are substantially equal. According to this structure, by adjusting the combination of diffraction gratings having different grating intervals in each incident area 330B, 330R, and 330G, it is possible to reduce a slight deviation of the projection position on the screen SC caused by the difference in the configuration of each incident area 330B, 330R, and 330G.

[0059] In addition, the projection device 310 of the present embodiment is provided with: a dichroic mirror 350b on the other side, which reflects the blue laser L10B from the blue light-emitting element 322B toward the diffractive optical element 330 side and allows the light from the green light-emitting element 322G to pass through; and a dichroic mirror 350a on one side, which reflects the light from the red light-emitting element 322R toward the diffractive optical element 330 side and allows the light from the green light-emitting element 322G to pass through, and is arranged at a position overlapping with the dichroic mirror 350b on the other side; the light from the blue light-emitting element 322B is irradiated at a position in the dichroic mirror 350b on the other side that is offset from the overlapping position and reflected toward the blue incident area 330B side; the light from the red light-emitting element 322R is irradiated at a position in the dichroic mirror 350a on one side that is offset from the above-mentioned overlapping position and reflected toward the red incident area 330R side. According to this configuration, the laser beams L10B, L10R, and L10G can be made incident on the corresponding incident regions 330B, 330R, and 330G of the diffractive optical element 330 , respectively.

[0060] As described above, in the projection devices 10, 110, 210, 310 of each embodiment, by projecting the light diffracted by the diffractive optical element 30, 130, 230, 330 in a point shape onto the liquid crystal display element 40, 140, 240, 340, it is possible to project an arbitrary pattern onto the screen (projection object) SC by simply controlling the orientation direction of the liquid crystal of the liquid crystal display element 40, 140, 240, 340. Furthermore, in the projection devices 110, 310 of the second embodiment and the fourth embodiment, by emitting blue, red, and green laser beams simultaneously, it is possible to realize full-color display on the screen (projection object) SC.

[0061] The various embodiments described above are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the main purpose of the invention. These embodiments and their variations are included in the scope and main purpose of the invention, and are included in the invention described in the claims and their equivalents. For example, in the various embodiments described above, a liquid crystal display element is illustrated as a display element, but is not limited to this. For example, a DMD (digital micromirror device) and a structure in which a light image is formed by the reflected light of the DMD can also be provided as a display element. In this case, it is also possible to project an arbitrary pattern onto the projected object by controlling the reflection form of the DMD.

Claims

1. A projection device, characterized in that: have: light source; a diffractive optical element into which the light from the light source is incident; and A display element, into which the light diffracted by the diffractive optical element is incident; The diffractive optical element projects the emitted light in a point shape toward the display element; The display element generates image light using at least a portion of the projected point-shaped light.

2. The projection device according to claim 1, characterized in that: The display element includes a liquid crystal display element.

3. The projection device according to claim 1, characterized in that: A projection port is provided for projecting the image light generated by the display element toward a projection object; The image light generated by the display element is projected from the projection port directly to the projection object or is projected from the projection port to the projection object via a reflection mirror.

4. The projection device according to claim 1, wherein: The diffractive optical element projects the emitted light directly toward the display element.

5. The projection device according to claim 1, characterized in that: The light sources include a first light source that emits light in a first wavelength band, a second light source that emits light in a second wavelength band, and a third light source that emits light in a third wavelength band.

6. The projection device according to claim 5, characterized in that: A moving mechanism is provided for moving the diffractive optical element on the optical path of the light from the light source; The light from the first light source, the light from the second light source, and the light from the third light source are incident on the diffractive optical element at different positions, respectively.

7. The projection device according to claim 5, characterized in that: The diffractive optical element is provided with a first region on the same plane where light from the first light source is incident, a second region on which light from the second light source is incident, and a third region on which light from the third light source is incident; The first region, the second region, and the third region have diffraction gratings with different grating intervals corresponding to the wavelength band of incident light.

8. The projection device according to claim 7, characterized in that: The first region, the second region, and the third region of the diffractive optical element diffract light so that the image lights emitted from the first region, the second region, and the third region, respectively, and projected onto a projection object, have substantially the same range.

9. The projection device according to claim 5, characterized in that: have: a first dichroic mirror that reflects the light from the first light source toward the diffractive optical element and transmits the light from the third light source; and a second dichroic mirror, which reflects the light from the second light source toward the diffractive optical element and transmits the light from the third light source, and is arranged so that a portion of the second dichroic mirror overlaps a portion of the first dichroic mirror when viewed from a predetermined direction; The diffractive optical element is provided with a first region on the same plane where light from the first light source is incident, a second region on which light from the second light source is incident, and a third region on which light from the third light source is incident; The first light source irradiates light toward a position in the first dichroic mirror that is offset from the overlapping position and reflected toward the first region; The second light source irradiates light toward a position in the second dichroic mirror that is offset from the overlapping position and reflected toward the second region.

10. The projection device according to claim 1, characterized in that: The light source mentioned above has a laser light source.

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