Projection device and projection method

Abstract

The goal is to reduce the occurrence of moiré patterns caused by display elements. [Solution] The projection device comprises a light source unit 31, a diffractive optical element 33, a prism unit 321, a drive unit, and a display element 34. The light source unit 31 has an LD311. The diffractive optical element 33 diffracts the incident light. The prism unit 321 refracts the light incident from the LD311 and emits it to the diffractive optical element 33. The drive unit rotates the prism unit 321. The display element 34 uses the diffracted light to generate light having an image of the projection target and projects it onto the display target object 2. By rotating, the prism unit 321 continuously changes the angle of the incident direction of the emitted light from the prism unit 321 with respect to the normal of the incident surface of the diffractive optical element 33.

Description

Technical Field

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

Background Art

[0002] Conventionally, a projection device including an LD (LASER Diode) light source and a DOE (Diffractive Optical Element) is known. The projection device forms a planar light composed of multiple bright spots by diffracted light multiple times based on the DOE. The projection device transmits the planar light through a display element such as an LCD (Liquid Crystal Display), and projects a pattern onto a display object using a projection system. The projection device has a feature of being able to efficiently illuminate a predetermined surface.

[0003] For example, a projector including a laser light source (LD light source), an electro-optical element, a collimating lens, an optical diffraction section (diffractive optical element), a spatial light modulator (display element), and a projection lens is known (see Patent Document 1). The projector deflects, collimates, and diffracts the light emitted from the LD light source, transmits the image generated by the display element, and projects it onto a screen (display object) using a projection system. The projector reduces speckle noise by superimposing a plurality of speckle patterns by changing the deflection angle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a possibility that the above projector may generate moiré between the planar pattern composed of multiple bright spots of diffracted light and the display element when the collimated light is incident on the diffractive optical element.

[0006] The objective of this invention is to reduce the generation of moiré patterns caused by display elements. [Means for solving the problem]

[0007] To solve the above problems, the projection apparatus of the present invention comprises a light source unit having at least one light source, a diffractive optical element that diffracts incident light, a prism unit that refracts light incident from the at least one light source and emits it to the diffractive optical element, a drive unit that rotates the prism unit, and a display element that generates light having an image of the projection target using the diffracted light and projects it onto the display target, wherein the rotation of the prism unit continuously changes the angle of the incident direction of the emitted light from the prism unit with respect to the normal of the incident surface of the diffractive optical element. [Effects of the Invention]

[0008] This invention makes it possible to reduce the occurrence of moiré patterns caused by display elements. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a projection device and a display object according to the first embodiment of the present invention. [Figure 2] This is a block diagram showing the functional configuration of a projection device. [Figure 3] This is a side view showing the image projection unit of the first embodiment. [Figure 4] This is a diagram showing the projected light of the first embodiment. [Figure 5] This is a side view showing the image projection unit of the second embodiment. [Figure 6] This figure shows the projected light of the second embodiment. [Figure 7] This is a side view showing the image projection unit of the third embodiment. [Figure 8] This is a schematic diagram showing the light source unit of the third embodiment. [Figure 9] This figure shows the pitch of the light source in the third embodiment. [Figure 10]This figure shows the projected light of the third embodiment. [Modes for carrying out the invention]

[0010] The first to third embodiments of the present invention will be described in detail below with reference to the drawings. However, the scope of the present invention is not limited to the illustrated examples.

[0011] A first embodiment of the present invention will be described with reference to Figures 1 to 4. As shown in Figure 1, the projection device 1 of this embodiment projects projection light L onto the object to be displayed 2, thereby displaying (projecting) various images onto the surface of the object to be displayed 2. The object to be displayed 2 may be, for example, a screen, the wall, floor, or ceiling of a building, or the surface of any object. In this embodiment, the distance d from the projection device 1 to the object to be displayed 2 is, for example, about 1 m to 10 m, but is not limited thereto. The image projected onto the surface of the object to be displayed 2 is not particularly limited, but may be, for example, an image of a sign to guide people in the vicinity, or an image to decorate the surface of the object to be displayed 2.

[0012] As shown in Figure 2, the projection device 1 includes a CPU (Central Processing Unit) 11, RAM (Random Access Memory) 12, a storage unit 13, a communication unit 14, an operation unit 15, an image projection unit 30, and the like. The image projection unit 30 includes a light source unit 31, an optical system drive unit 320, an optical system 32, a diffractive optical element 33, a display element 34, and the like. All parts of the projection device 1, except for the optical system 32 and the diffractive optical element 33, are connected via a bus 16. The projection device 1 may further include other components such as a display unit for displaying status information of the projection device 1, a speaker, etc.

[0013] The CPU 11 controls each part of the projection device 1. The CPU 11 reads various programs stored in the memory unit 13, loads them into the RAM 12, and executes various processes in cooperation with the loaded programs. The RAM 12 is a volatile semiconductor memory that temporarily stores programs and data, and a work area is formed therein.

[0014] The memory unit 13 is composed of flash memory or the like, is a read-and-write non-volatile memory, and stores various programs and data. The memory unit 13 can also store image data and other data received from external devices via the communication unit 14, according to instructions from the CPU 11. The communication unit 14 is a communication module for wired communication with external devices such as PCs (Personal Computers) using communication standards such as USB (Universal Serial Bus). The CPU 11 sends and receives information with external devices via the communication unit 14. The external device transmits image data to be projected to the projection device 1. The communication unit 14 may also be a communication module for wireless communication with external devices using communication standards such as wireless LAN (Local Area Network). The operation unit 15 has buttons, a remote control and its receiver, and receives various operation inputs from the user, outputting the operation information to the CPU 11.

[0015] The light source unit 31 is a module (package) on which one LD is mounted as a light source. The light source unit 31 is assumed to have the LD311 (Figure 3) arranged as a semiconductor chip. The LD311 emits monochromatic (for example, green) laser light. The color of the laser light from the LD311 is not limited to green, but may be other colors such as red or blue. The optical system drive unit 320 is a drive unit that rotates the optical system 32 according to the control of the CPU 11. The optical system 32 is an optical system that refracts the laser light emitted from the light source unit 31 and causes it to enter the diffractive optical element 33, and has a rotatable structure. With respect to light incident on the same position in the optical system 32, the direction and position of the emitted light are continuously changed by rotation, and the direction and position of the emitted light return to their original state after one full rotation.

[0016] The diffractive optical element 33 is a diffractive grating (DOE) having a three-dimensional uneven structure in which a plurality of diffractive gratings with different grating periods are combined. The diffractive optical element 33 diffracts the incident laser light according to the pitches of a plurality of grating periods, and emits diffracted light of a higher order composed of a dot pattern of a plurality of bright spots where the diffracted light with a matrix (grating) pattern interferes and enhances each other. The display element 34 is a transmissive liquid crystal display element arranged perpendicular to the optical axis of the LD 311. The display element 34 includes a dot matrix type liquid crystal panel in which pixels are arranged in a matrix, polarizing plates arranged on both sides so as to sandwich the liquid crystal panel, and a liquid crystal drive circuit for driving the liquid crystal panel. The liquid crystal drive circuit applies a drive voltage corresponding to the pixel value of the image to be projected (displayed) to each pixel based on the image data stored in the storage unit 13 under the control of the CPU 11, and controls the alignment state of the liquid crystal layer of each pixel. In response to the application of the drive voltage, each pixel switches between a state (on state) in which the light incident on the pixel passes through the polarizing plate on the emission side and a state (off state) in which the light incident on the pixel is absorbed by the polarizing plate on the emission side. The display element 34 distributes the on-state pixels based on the image data, transmits the image of the image data, and projects the transmitted light onto the display object 2 to display the image.

[0017] As shown in FIG. 3, in the image projection unit 30, the optical system 32, the diffractive optical element 33, and the display element 34 are arranged in order along the optical axis L0 of the light source unit 31 up to the display object 2. The optical axis L0 is taken in the horizontal direction. The Z-axis is taken parallel to the optical axis L0, and the axis is such that the light traveling direction of the optical axis L0 is the +Z direction. Also, the X-axis is an axis with the zenith direction as the +X direction. Furthermore, the Y-axis is an axis in a direction perpendicular to the X-axis and the Z-axis. These three-dimensional XYZ axes are the same in other figures. The optical system 32 has a prism unit 321. The prism unit 321 has one trapezoidal prism that can rotate around the optical axis L0. The prism unit 321 may be one triangular prism. The prism unit 321 is rotated by the optical system drive unit 320 and continuously changes the predetermined angle A of the light beam incident from the LD 311 and emits it. The angle A is the angle of the incident direction of the emitted light (0th order light) of the prism unit 321 with respect to the normal (Z-axis) of the incident surface on the -Z direction side of the diffractive optical element 33. The emitted light of the prism unit 321 can be displaced from the incident position corresponding to the optical axis L0 on the incident surface of the diffractive optical element 33 due to the rotation of the prism unit 321.

[0018] The diffractive optical element 33 is arranged such that the longitudinal direction of the diffractive rectangular plane is parallel to the X-axis. The display element 34 is arranged such that the longitudinal direction of the rectangular plane of the pixel array is parallel to the X-axis. The display object 2 is arranged such that the longitudinal direction of the projection rectangular plane is parallel to the X-axis. In particular, the display element 34 is arranged such that a plurality of pixels are arranged in a matrix in the XY plane.

[0019] The 0th-order light after diffraction in the light emitted from LD311 is denoted as light L10, and the 1st-order (-1st-order light), 2nd-order (-2nd-order light), 3rd-order (-3rd-order light), and 4th-order (-4th-order light) are denoted as lights L11, L12, L13, and L14, respectively. Light emitted from the light source unit 31 is incident on the diffractive optical element 33 via the rotating prism unit 321 and diffracted. The diffractive light emitted from the diffractive optical element 33 is projected onto the display object 2 as projected light L having an image via the display element 34. As a result, as shown in Figure 4, a dot pattern consisting of multiple dots D1 is arranged in the projected light projected onto the display object 2. The dots D1 are, for example, circular trajectories in which bright spots based on diffracted light continuously move due to one rotation of the prism unit 321, and are approximately circular with a diameter larger than the bright spot. The projection light from the dot pattern of dot D1 enlarges and homogenizes the bright spots, thereby reducing the occurrence of moiré patterns based on the display element 34 and also reducing the generation of speckle noise. Speckle noise is an irregular, spotty pattern that appears due to the interference of scattered light.

[0020] Increasing the diameter of dot D1 further reduces the occurrence of moiré and speckle noise. Further increasing the diameter of dot D1 so that dots D1 overlap further reduces the occurrence of moiré. However, if the diameter of the circular trajectory of the bright spot is too large, a dark region will appear in the center of dot D1, so it is preferable to set the prism section 321 so that no dark region occurs.

[0021] In the projection device 1, when the CPU 11 receives an input from the user via the operation unit 15 for an image display instruction, it lights up the LD 311 of the light source unit 31. The CPU 11 rotates the optical system 32 via the optical system drive unit 320. The CPU 11 reads image data containing the image to be projected from the storage unit 13. The CPU 11 causes the display element 34 to generate an image corresponding to the read image data and projects (displays) the projection light L containing the image onto the display target object 2.

[0022] As described above, according to this embodiment, the projection device 1 comprises a light source unit 31, a diffractive optical element 33, a prism unit 321, an optical system drive unit 320, and a display element 34. The light source unit 31 has one LD311. The diffractive optical element 33 diffracts the incident light. The prism unit 321 refracts the light incident from the LD311 and emits it to the diffractive optical element 33. The optical system drive unit 320 rotates the prism unit 321. The display element 34 uses the diffracted light to generate light having an image of the projection target and projects it onto the display target object 2. By rotating, the prism unit 321 continuously changes the angle A of the incident direction of the emitted light from the prism unit 321 with respect to the normal to the incident surface of the diffractive optical element 33. Therefore, the generation of moiré by the display element 34 can be reduced by a dot pattern of large-diameter dots obtained by rotating the bright spots. Furthermore, the generation of speckle noise can be further reduced. Furthermore, since the direction of the angle of the 0th-order light (the light emitted from the prism section 321) is changed rather than the position relative to the diffractive optical element, it is not necessary to change a predetermined angle A depending on the projection size. In addition, since the light source section 31 has one LD311, the light source section 31 can be easily constructed.

[0023] Furthermore, the prism section 321 is rotated around the optical axis L0 of the light source section 31. This allows for easy and continuous changes in the angle A of the incident direction of the light emitted from the prism section 321 with respect to the normal to one of the incident planes of the diffractive optical element 33.

[0024] Next, a second embodiment of the present invention will be described with reference to Figures 5 and 6. In the first embodiment, the optical system 32 has one prism and has a simple configuration, but there is a risk that the incident position of light on the diffractive optical element 33 may shift from the position of the optical axis L0. If the incident position of light on the diffractive optical element 33 shifts from the position of the optical axis L0, the center of the projected light dot will shift, the dot will be projected to an unintended size and position, and the position of the dot will also shift due to the change in projection size. In this embodiment, the optical system has two prisms, so that the incident position of light on the diffractive optical element 33 does not shift from the position of the optical axis L0 even when the optical system is rotated.

[0025] This embodiment uses the projection device 1, similar to the first embodiment. However, the image projection unit 30 of the projection device 1 is replaced with an image projection unit 30a. Therefore, the same reference numerals are used for the same parts as in the projection device 1 of the first embodiment, and their descriptions are omitted. The differences will be described primarily.

[0026] As shown in Figure 5, the image projection unit 30a includes a light source unit 31, an optical system 32a, a diffractive optical element 33, and a display element 34. The optical system 32a includes prisms 321a and 322a as a prism section. Prism 321a is the -Z direction side of the two prisms and is a rotatable trapezoidal prism with a small refraction (small difference between the length of the upper base and the length of the lower base of the trapezoid). Prism 322a is the +Z direction side of the two prisms and is a rotatable trapezoidal prism with a larger refraction (larger difference between the length of the upper base and the length of the lower base of the trapezoid) than prism 321a. Prisms 321a and 322a may also be triangular prisms. Prism 321a rotates and refracts and emits light incident from LD311. As the prism 322a rotates, it directs the light emitted from the prism 321a towards a single point corresponding to the optical axis L0 of the incident surface of the diffractive optical element 33. Therefore, the light emitted from the LD 311 is directed towards a single point on the incident surface of the diffractive optical element 33, regardless of the rotation of the optical system 32a.

[0027] The 0th-order light after diffraction in the light emitted from LD311 is designated as light L20, and the 1st-order (-1st-order light), 2nd-order (-2nd-order light), 3rd-order (-3rd-order light), and 4th-order (-4th-order light) are designated as lights L21, L22, L23, and L24, respectively. Light emitted from the light source 31 is incident on the diffractive optical element 33 via the rotating prisms 321a and 322a in sequence and is diffracted. The diffractive light emitted from the diffractive optical element 33 is projected onto the display object 2 as projected light L having an image via the display element 34. As a result, as shown in Figure 6, a dot pattern consisting of multiple dots D2 is arranged in the projected light projected onto the display object 2. The dots D2 become, for example, circular trajectories of bright spots based on the diffractive light due to the rotation of the prisms 321a and 322a, and have a larger diameter than the bright spots themselves. The center position of dot D2 is the position of the bright spot diffracted by light incident on the incident surface of the diffractive optical element 33 from the optical axis L0. Therefore, even if the projection size changes, the center of the projected light dot does not shift, and the size and position of the dot relative to the display area do not shift.

[0028] As described above, according to this embodiment, the optical system 32a as a prism section includes a prism 321a as a first prism and a prism 322a as a second prism. Prism 321a is a rotatable prism that refracts and emits light incident from LD311. Prism 322a is a rotatable prism that emits light emitted from prism 321a to a single point on the incident surface of the diffractive optical element 33. Therefore, light emitted from LD311 can be emitted to a single point on the incident surface of the diffractive optical element 33 regardless of the rotation of the optical system 32a. Thus, the shift in the bright spot of the projected light on the display object 2 can be reduced, the shift in the center of the projected light dot can be reduced even if the projection size changes, and the shift in the size and position of the dot with respect to the display area can be reduced.

[0029] Furthermore, one point on the incident surface of the diffractive optical element 33 is a point that passes through the optical axis L0 of the light source unit 31. Therefore, the shift in the bright spot of the projected light on the display object 2 can be further reduced, the shift in the center of the projected light dots can be further reduced even when the projection size changes, and the shift in the size and position of the dots relative to the display area can be further reduced.

[0030] Furthermore, the degree of refraction of prism 322a is greater than that of prism 321a. Therefore, the light emitted from LD311 can be easily and accurately directed towards a single point on the incident surface of the diffractive optical element 33, regardless of the rotation of the optical system 32a.

[0031] Next, a third embodiment of the present invention will be described with reference to Figures 7 to 10. In the first embodiment, the light source unit 31 had one LD311. In this embodiment, in order to improve the light output, the light source unit has a configuration with multiple LDs. This embodiment uses the projection device 1, as in the first embodiment. However, in the projection device 1, the image projection unit 30 is replaced with an image projection unit 30b. For this reason, the same reference numerals are used for the same parts as in the projection device 1 of the first embodiment, and their descriptions are omitted, while the different parts will be described mainly.

[0032] As shown in Figure 7, the image projection unit 30b includes a light source unit 31b, an optical system 32b, a diffractive optical element 33, and a display element 34. The light source unit 31b is an MCM (Multi Chip Module), which is a module (package) on which multiple LDs 314, 315, 316, and 317 are mounted. The light source unit 31b has four LDs 314, 315, 316, and 317 arranged in two dimensions (2x2) so that the light emission directions are parallel. As shown in Figure 8, LDs 315 and 314 are arranged sequentially in the one-dimensional array direction in the +X direction on the -Y direction side. LDs 317 and 316 are arranged sequentially in the one-dimensional array direction in the +X direction on the +Y direction side. In other words, LDs 314 and 316 are arranged sequentially in the one-dimensional array direction in the +Y direction on the +X direction side. Similarly, LDs 315 and 317 are arranged sequentially in the one-dimensional array direction in the +Y direction on the -X direction side. As shown in Figure 9, LD315 and 314 are arranged with a pitch P1 between them. LD314 and 316 are arranged with a pitch P2 between them. LD314, 315, 316, and 317 are assumed to emit light of the same color (for example, green). However, the number of LDs in the light source unit 31b and the color of the emitted light are not limited to the above configuration.

[0033] The optical system 32b includes a condenser optical system 323 and a prism section 321b. The condenser optical system 323 condenses the light incident from LD314 to LD317 onto the prism section 321b. When the pitch P1 is the same as the pitch P2, the condenser optical system 323 is, for example, a condenser optical system having a spherical convex lens. When the pitch P1 is different from the pitch P2, the condenser optical system 323 is, for example, a condenser optical system having a cylindrical lens and a concave lens. The cylindrical lens has convex lens surfaces in the cross section of the XZ plane and the cross section of the YZ plane, respectively. The cylindrical lens refracts the laser light emitted from the light source section 31b and emits it to the concave lens. In the cylindrical lens, the curvature of the convex lens surface in the cross section of the XZ plane is defined as the first curvature, and the curvature of the convex lens surface in the cross section of the YZ plane is defined as the second curvature. When P1 < P2, the first curvature > the second curvature. When P1 > P2, the first curvature < the second curvature. The concave lens is a double-sided concave lens or a single-sided concave lens. The concave lens refracts the light incident from the cylindrical lens, emits it to the prism section 321b, and condenses it. Note that the optical system 32b may also be configured to include a cylindrical lens and a concave lens such that when the pitch P1 is the same as the pitch P2, P1 = P2 and the first curvature = the second curvature. Furthermore, the optical system 32b may be configured without the condenser optical system 323.

[0034] Similar to the prism section 321 of the first embodiment, the prism section 321b is a trapezoidal prism that is rotatable about the optical axis L0, but it may also be a triangular prism. By rotation, the prism section 321b continuously changes a predetermined angle A of the light beam incident from LD314 to LD317 and emits it. The emitted light corresponding to LD311 to LD314 of the prism section 321b is incident on the incident surface of the diffractive optical element 33, for example, at a single point. The emitted light of the prism section 321b is diffracted by the diffractive optical element 33 and projected (displayed) onto the display object 2 as projection light including an image through the display element 34.

[0035] The 0th order light after diffraction in the emitted light from LD314 and 316 is designated as light L40, and similarly, the 1st (-1st order light), 2nd (-2nd order light), 3rd (-3rd order light), and 4th (-4th order light) are designated as lights L41, L42, L43, and L44, respectively. The 0th order light after diffraction in the emitted light from LD315 and 317 is designated as light L50, and similarly, the 1st (-1st order light), 2nd (-2nd order light), 3rd (-3rd order light), and 4th (-4th order light) are designated as lights L51, L52, L53, and L54, respectively. As a result, as shown in Figure 10, a dot pattern consisting of multiple dots D4 and D5 is arranged in the projected light projected onto the display target object 2. Dots D4 and D5, due to the rotation of the prism section 321b, form, for example, circular trajectories of bright spots based on diffracted light, and have a larger diameter than the bright spots themselves. Dot D4 consists of bright spots corresponding to the diffracted light of the emitted light from LDs 314 and 316. Dot D5 consists of bright spots corresponding to the diffracted light of the emitted light from LDs 315 and 317. The projection light of the dot patterns of dots D4 and D5 enlarges and homogenizes the bright spots, thereby reducing the generation of moiré patterns based on the display element 34 and also reducing the generation of speckle noise.

[0036] As described above, according to this embodiment, the light source unit 31b has four LDs 314 to 317. The projection device 1 includes a focusing optical system 323. The focusing optical system 323 focuses the light emitted from the LDs 314 to 317 onto the prism unit 321b. Therefore, the brightness of the projected light on the display object 2 can be increased and the brightness can be made uniform.

[0037] The above description of the embodiment is merely an example of the projection apparatus and projection method according to the present invention, and is not limited thereto. For example, the above embodiment describes a configuration in which a monochromatic image is projected using monochromatic laser light emitted from one light source unit 31, 31a, 31b, but is not limited thereto. For example, a color image may be projected using multiple light source units that emit laser light of different colors. In this case, the image projection unit has intersecting first and second dichroic mirrors, a blue light source unit that emits laser light in the blue wavelength band, a green light source unit that emits laser light in the green wavelength band, and a red light source unit that emits laser light in the red wavelength band. The first dichroic mirror reflects laser light in the blue wavelength band and transmits laser light in other wavelength bands. The second dichroic mirror reflects laser light in the red wavelength band and transmits laser light in other wavelength bands. The blue light source is positioned at an angle at which the emitted laser light is reflected by the first dichroic mirror and incident on the optical system. The green light source is positioned at an angle such that the emitted laser light passes through the first and second dichroic mirrors and enters the optical system. The red light source is positioned at an angle such that the emitted laser light is reflected by the second dichroic mirror and enters the optical system. In this configuration, the blue, green, and red light sources are emitted at exclusive timings, and during the emission period of each color, the display element is driven with image data corresponding to the color of the emitting light source. This allows for the superimposition of blue, green, and red images onto the display object to project a color image.

[0038] Furthermore, although the above embodiment described a display element 34 that can switch each pixel of the liquid crystal panel between two grayscale states (on and off), it is not limited to this. The display element may also be able to switch each pixel between three or more grayscale states (for example, 256 grayscale states). That is, the orientation state and transmittance of the liquid crystal of each pixel of the liquid crystal panel may be switchable between three or more steps (for example, 256 steps). In this case, the image data should be such that the pixel value of each pixel can take the value of the number of display grayscale levels of the liquid crystal panel.

[0039] Furthermore, although a liquid crystal display element having a liquid crystal panel was described as the display element 34 in the above embodiment, the invention is not limited to this. The display element may be, for example, a DMD (Digital Micromirror Device). A DMD has a plurality of micro-mirrors arranged in an array, and by switching the tilt angle of each micro-mirror according to the image data, it forms projected light having the image of the object to be projected onto using the reflected light from the plurality of micro-mirrors.

[0040] While embodiments of the present invention have been described, the scope of the present invention is not limited to the embodiments described above, but includes the scope of the invention as described in the claims and its equivalents. [Explanation of Symbols]

[0041] 1 Projection device, 31, 31b Light source unit, 311, 314~317 LD, 321, 321b Prism unit, 321a, 322a Prism, 33 Diffractive optical element, 34 Display element

Claims

1. A light source unit having at least one light source, A diffractive optical element that diffracts incident light, A prism section that refracts light incident from at least one light source and emits it to the diffractive optical element, A drive unit for rotating the prism section, The system includes a display element that generates light having an image of the object to be projected onto using the diffracted light and projects it onto the object to be displayed. The prism portion is a projection device that, by rotation, continuously changes the angle of the incident direction of the light emitted from the prism portion with respect to the normal to the incident surface of the diffractive optical element.

2. The projection apparatus according to claim 1, wherein the prism portion is rotated around the optical axis of the light source portion.

3. The projection apparatus according to claim 1, wherein the prism section has one prism.

4. The prism section is A rotatable first prism that refracts and emits light incident from at least one light source, The projection apparatus according to claim 1, further comprising a rotatable second prism that directs the light emitted from the first prism to a single point on the incident surface of the diffractive optical element.

5. The projection apparatus according to claim 4, wherein one of the points on the incident surface is a point passing through the optical axis of the light source.

6. The projection apparatus according to claim 4 or 5, wherein the refraction of the second prism is greater than the refraction of the first prism.

7. The light source unit has a plurality of light sources, The projection apparatus according to claim 1, further comprising a focusing optical system that focuses light emitted from the plurality of light sources into the prism section.

8. The prism section refracts and emits light incident from at least one light source in a light source section having at least one light source, The drive unit performs the step of rotating the prism section, The diffractive optical element diffracts the light incident from the prism portion, The display element includes the step of generating light having an image of the object to be projected onto using the diffracted light and projecting it onto the object to be displayed, The prism portion is a projection method that continuously changes the angle of the incident direction of the light emitted from the prism portion with respect to the normal of the incident surface of the diffractive optical element by the rotation of the prism portion.

Images