JP2018128582A - Video display device and video display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology that efficiently displays a video of high picture quality.SOLUTION: Provided is a video display device comprising: a laser light source unit for emitting a laser beam; a condensing optical unit for condensing the light emitted from the laser light source; a light diffusion unit of transmission type for diffusing the light from the condensing optical unit; an image forming optical unit for forming an image on a projection plane using the light diffused by the light diffusion unit; and a scanning unit for scanning the light from the image forming optical unit on to the projection plane. The image forming optical unit accepts as its input the light of a radius whose value is smaller than or equal to the beam diameter on the projection plane and an effective diameter in the scanning unit extrapolated by a first distance from the projection plane to the scanning unit and a second distance from the projection plane to the image forming optical unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a video display device and a video display system.

  Patent Document 1 discloses a technique related to a laser projection apparatus. In the example of this document, in paragraph [0017], “The laser projection apparatus 101 of the present embodiment is a laser scanning laser projection apparatus, and the diffusion unit 150 is provided in the condensing region of the emitted light from the laser light source 110. The laser beam that is arranged, transmitted through the diffusion unit 150, and collimated again is scanned on the screen 201 by the scanning mechanism 140 to generate an image.

JP 2011-2547 A

  In an image display device using laser light, it is required to reduce speckles generated due to the coherence of the laser.

  Although the technique described in Patent Document 1 aims to reduce speckle, since the collimated light is projected onto the screen, the resolution of the projected image may be lowered.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a technique for efficiently displaying an image with high image quality.

  The present application includes a plurality of means for solving at least a part of the above-described problems. Examples of the means are as follows.

  In order to solve the above problems, an image display device according to an aspect of the present invention includes a laser light source unit that emits laser light, a condensing optical unit that collects light emitted from the laser light source unit, and the collector. A transmissive light diffusing unit that diffuses light from the optical optical unit, an imaging optical unit that forms an image on a projection surface using the light diffused by the light diffusing unit, and the light from the imaging optical unit A scanning unit that scans on the projection surface, and the imaging optical unit determines a beam diameter on the projection surface and an effective diameter on the scanning unit as a first distance from the projection surface to the scanning unit, and Light having a diameter equal to or smaller than a value extrapolated using the second distance from the projection surface to the imaging optical unit is incident.

  According to the present invention, it is possible to provide a technique for efficiently displaying a video with high image quality.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a figure which shows the structural example of the video display system in 1st Embodiment. It is a figure which shows the structural example of the laser light source part in 1st Embodiment. It is a figure which shows the structural example of the phase provision part in 1st Embodiment. It is a figure for demonstrating the installation conditions of a light-diffusion part, an imaging optical part, a scanning part, and a screen. 1 is a diagram illustrating a configuration example of a video display device according to a first embodiment. It is a figure for demonstrating the light-diffusion part in the modification of 1st Embodiment. It is a figure which shows the structural example of the phase provision part in 2nd Embodiment. It is a figure which shows the structural example of the phase provision part in 3rd Embodiment. It is a figure which shows the structural example of the phase provision part in 4th Embodiment.

  In a conventional image display device using laser light, light emitted to a screen is given a phase according to the unevenness of the screen surface and is scattered. Part of the light scattered on the screen reaches the user's retina. Since the laser has coherence, the light reaching the user's retina may be strengthened or weakened depending on the phase applied by the screen.

  Thereby, the user visually recognizes a random speckle pattern called speckle on the screen. When speckles are superimposed on the image projected on the screen, the image quality visually recognized by the user is reduced.

  <First Embodiment>

  Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a video display system 1 according to the first embodiment. The video display system 1 includes a video display device 2 and a screen 3.

  The video display device 2 is a device that scans a laser beam and displays a video image 11 on a screen 3 that is a projection surface. The video display device 2 includes a laser light source unit 100, a phase applying unit 110, and a scanning unit 120. Although details will be described later, the laser light source unit 100 emits visible light for displaying the video 11 to the user.

  The phase applying unit 110 adds a phase to the light incident from the laser light source unit 100 and emits the light to the scanning unit 120. The scanning unit 120 scans the image 11 on the projection plane using the scanning element 121. The scanning element 121 includes a mirror surface, reflects the laser light incident from the phase applying unit 110 using the mirror surface, and scans the screen 3.

  The mirror surface rotates about two axes, for example, and scans the laser beam on the screen 3. More specifically, the mirror surface has a first rotation axis that scans the laser light on the screen 3 in the y direction (vertical direction) shown in FIG. 1, and the x direction (horizontal direction) that shows the laser light in FIG. Rotate around a second rotation axis that scans at the same time. The first rotation axis and the second rotation axis are orthogonal to each other.

  The image display device 2 in the present embodiment drives the image on the screen 3 by driving in synchronization with the rotation of the mirror surface by the first rotation axis and the second rotation axis and the output intensity by the laser light source unit 100. 11 can be displayed.

  Although the scanning unit 120 shown in FIG. 1 includes one scanning element 121, the present invention is not limited to this. For example, the scanning unit 120 may include two scanning elements 121 each having a mirror surface. Each scanning element 121 rotates with a different rotation axis. The scanning unit 120 only needs to scan the laser light in the x direction and the y direction on the screen 3 by the rotation of each scanning element 121.

  The screen 3 may vibrate or rotate during video display. The screen 3 vibrates in the horizontal direction (x direction) or the vertical direction (y direction) by a drive mechanism (not shown). Alternatively, when the screen 3 at a certain point in time is used as a reference plane, it rotates in parallel with the reference plane with the normal line of the reference plane as the central axis.

  Thereby, the speckle pattern visually recognized by the user changes dynamically. That is, it is possible to obtain an effect of reducing the speckle pattern by time integration of the speckle pattern.

  FIG. 2 is a diagram illustrating a configuration example of the laser light source unit 100 according to the first embodiment. The laser light source unit 100 includes laser light sources 101a, 101b, and 101c and dichroic mirrors 102a and 102b. Hereinafter, when it is not necessary to distinguish the laser light sources 101a, 101b, and 101c, they are referred to as laser light sources 101.

  The laser light sources 101a, 101b, and 101c are, for example, laser diodes, and emit laser beams of different colors. For example, the laser light source 101a emits “R (red)” laser light, the laser light source 101b emits “G (green)” laser light, and the laser light source 101c emits “blue” laser light.

  The dichroic mirrors 102a and 102b multiplex the light emitted from the laser light source 101. In the laser light source unit 100, the laser light source 101 and the dichroic mirrors 102a and 102b are arranged so that the three colors of laser light travel in substantially the same direction with substantially the same optical axis.

  The number of laser light sources 101 included in the laser light source unit 100 is not limited to this. For example, the laser light source unit 100 may project the image 11 on the screen 3 using one or two laser light sources 101. Alternatively, the laser light source unit 100 may use a plurality of laser light sources 101 for each color to increase the light output intensity.

  FIG. 3 is a diagram illustrating a configuration example of the phase applying unit 110 according to the first embodiment. The phase imparting unit 110 includes a condensing optical unit 130, a light diffusing unit 140, and an imaging optical unit 150. The condensing optical unit 130 includes a condensing lens 131. The condensing optical unit 130 condenses the light emitted from the laser light source unit 100 on the light diffusion unit 140 using the condensing lens 131.

  The light diffusion unit 140 includes at least one transmission type diffusion member 141 and diffuses incident light. The transmissive diffusing member 141 is, for example, a transmissive diffusing plate that does not substantially disturb the polarization of incident light. In other words, the transmission type diffusing member 141 has a substantially single polarization of the transmitted light when a single polarized light is incident. The transmission type diffusion member 141 is, for example, a transmission type surface diffusion plate.

  The transmissive diffusion member 141 may be, for example, a transmissive diffraction grating. A specific pattern is repeatedly arranged on the transmission diffraction grating. The light incident on the transmissive diffraction grating spreads by diffraction and is emitted toward the imaging optical unit 150. For example, a grating-shaped pattern is arranged in the transmission type diffraction grating. By optimizing the grating shape, the light diffusion unit 140 can obtain a desired diffraction pattern and a desired diffraction intensity distribution.

  Moreover, the transmissive | pervious diffusion member 141 may be plural, for example. In that case, each transmission type diffusing member 141 is installed in the light diffusing unit 140 in multiple stages. The light incident on the light diffusing unit 140 is diffused as it passes through the transmissive diffusing member 141, and is emitted toward the imaging optical unit 150. Thereby, the selectivity of the diffusing member is increased, and the light distribution of the transmitted light can be set to a desired distribution.

  The imaging optical unit 150 forms an image on the projection plane using the light diffused by the light diffusion unit 140. The imaging optical unit 150 includes a lens 151. The lens 151 is preferably composed of an optical system or an optical component having good light collecting performance. The lens 151 is, for example, a plano-convex lens in which the light diffusion unit 140 side is flat, a meniscus lens in which the light diffusion unit 140 side is concave, or an aspheric lens.

  In the present embodiment, the light reaching the phase applying unit 110 from the laser light source unit 100 enters the condensing optical unit 130. The profile of light incident on the condensing optical unit 130 may be collimated light, diffused light, or convergent light.

  The condensing optical unit 130 emits the incident light to the light diffusion unit 140. The installation position of the light diffusing unit 140 is within a range where the light emitted from the condensing optical unit 130 is condensed. Note that the range in which light is condensed is, for example, a range in which the radius of light is less than or equal to √2 times the beam waist radius. This range coincides with a range whose length is twice the Rayleigh length with the beam waist position as the center.

  The light diffusing unit 140 diffuses the light incident from the condensing optical unit 130 and emits the light to the imaging optical unit 150. The imaging optical unit 150 stops the incident diffused light and emits it to the scanning unit 120. The scanning unit 120 scans the light emitted from the imaging optical unit 150 onto the screen 3 that is a projection surface.

  Note that the transmission type diffusing member 141 included in the light diffusing unit 140 in the present embodiment does not substantially disturb the polarization. Therefore, the laser light source unit 100 emits laser light having substantially single polarized light, and the condensing optical unit 130, the imaging optical unit 150, and the scanning unit 120 are configured to substantially maintain polarized light. The video display device 2 can output light of substantially single polarized light.

  Further, when the spread angle of the light diffused by the light diffusing unit 140 is θ as a half angle, the radius of the diffused light at a position away from the light diffusing unit 140 by the distance L is L × tan θ. The light diffused by the light diffusing unit 140 is collected on the screen 3 by the imaging optical unit 150, but the effective radius of the scanning unit 120 positioned between the imaging optical unit 150 and the screen 3 must be taken into consideration. In addition, the light emitted from the imaging optical unit 150 protrudes from the effective radius of the scanning unit 120, leading to a decrease in light utilization efficiency.

  The imaging optical unit 150 generates an image of the object surface on the screen 3 with the light diffusing unit 140 as an object surface and the screen 3 as an image surface. The beam diameter in the light diffusing unit 140 and the imaging optical system If the optical magnification is not taken into consideration, the beam radius on the screen 3 becomes large, and the resolution of the image 11 is lowered. Further, the image 11 with good image quality cannot be displayed unless the beam diameter in the light diffusing unit 140 and the pattern interval of the light diffusing unit 140 are taken into consideration.

  Therefore, in the present embodiment, each component of the phase adding unit 110 is adjusted in order to efficiently display a video with high image quality. Hereinafter, the installation conditions of each component of the phase provision part 110 are demonstrated.

  FIG. 4 is a diagram for explaining the installation conditions of the light diffusing unit 140, the imaging optical unit 150, the scanning unit 120, and the screen 3. The radius of light on the exit side of the light diffusing unit 140 is h, the radius of the imaging optical unit 150 is R, the effective radius of the scanning unit 120 is r, and the spread angle of the light diffused by the light diffusing unit 140 is a half angle θ. To do. The radius of the imaging optical unit 150 is synonymous with the radius of the lens 151, for example. Further, the distance between the light diffusing unit 140 and the imaging optical unit 150 is a, the distance between the imaging optical unit 150 and the screen 3 is b, and the distance between the scanning unit 120 and the screen 3 is c. The distance c between the scanning unit 120 and the screen 3 is substantially equal to the projection distance of the video display device 2.

  The light diffused by the light diffusion unit 140 enters the imaging optical unit 150 and is emitted toward the scanning unit 120. The light emitted from the imaging optical unit 150 is scanned by the scanning unit 120 and reaches the screen 3. The phase applying unit 110 generates an image of the object surface on the screen 3 with the light diffusion unit 140 as the object surface. The imaging optical unit 150 is preferably composed of optical components having a high numerical aperture (NA) in order to capture more light diffused by the light diffusion unit 140.

  For example, the imaging optical unit 150 may have a numerical aperture of approximately sin θ or more. Thereby, the light emitted from the light diffusing unit 140 can be prevented from leaking out of the imaging optical unit 150.

  The divergence angle θ is an angle corresponding to the minimum solid angle at which a predetermined proportion of light can be taken out of the energy of the light emitted from the light diffusion unit 140. For example, if the predetermined ratio is ½, the angle at which ½ of the energy of the light emitted from the light diffusing unit 140 can be captured is set to θ, so that the imaging optical unit 150 is moved outside. The leaking light can be suppressed to ½ or less.

  Further, n is the number of pixels to be resolved per unit length of the video 11 displayed on the screen 3 by the video display device 2. For example, when the length of the image 11 on the screen 3 in the x direction and the y direction is L and L × g, respectively, and the number of pixels in the x direction and the y direction of the image 11 to be displayed is m and m × g. To do. When each pixel of the video 11 is resolved, n = m / L.

  Generally, n = m / (k × L) when resolving every k pixels of the video 11. In order to display the video 11 with high resolution, it is preferable to configure the video display system 1 so that k ≦ 5.

  Further, since the number of pixels to be resolved per unit length is n, the video display device 2 is configured so that the radius H of the light projected on the screen 3 is approximately equal to 1 / 2n. It is preferable that H = 1 / 2n.

  Further, the mirror surface of the scanning element 121 included in the scanning unit 120 is circular, and the radius of the circular is s. Since the effective radius of the scanning unit 120 is r, it can be said that r = s × cos ψ when the incident angle of light incident on the scanning unit 120 from the imaging optical unit 150 is ψ.

  In order to project light having a radius H on the screen 3 without leakage of light emitted from the imaging optical unit 150 to the outside of the scanning unit 120 having an effective radius r, the video display device 2 has the following configuration. Specifically, the imaging optical unit 150 determines the beam diameter on the screen, which is the projection surface, and the effective diameter in the scanning unit 120, the distance from the projection surface to the scanning unit 120, and the distance from the projection surface to the imaging optical unit 150. It is comprised so that the light of the diameter below the value extrapolated using may be incident.

  That is, a radius less than or equal to a value obtained by extrapolating the light radius H on the screen 3 and the effective radius r on the scanning unit 120 using the distance c from the screen to the scanning unit 120 and the distance b from the screen to the imaging optical unit 150. Is incident on the imaging optical unit 150. In other words, the radius R of the light incident on the imaging optical unit 150 satisfies the following condition.

  R ≦ {(r−H) × b / c} + H

  Further, since the light diffusing unit 140 and the screen 3 are in the relationship between the object plane and the image plane, the radius h of the light emitted from the light diffusing unit 140 is H in order to set the radius of light on the screen 3 to H. The video display device 2 is configured so as to be approximately equal to or less than a value obtained by dividing by the optical magnification (b / a).

  Further, since the spread angle of the light diffused by the light diffusing unit 140 is a half angle θ, the radius of the light in the imaging optical unit 150 when the light diffused by the light diffusing unit 140 reaches the imaging optical unit 150 R can be expressed as h + a × tan θ. Therefore, the video display device 2 is configured to satisfy the following conditions.

  h + a × tan θ ≦ {(r−H) × b / c} + H

  The representative length of the diffusion pattern of the light diffusion unit 140 is defined as the correlation length of the phase pattern imparted to the light by the light diffusion unit 140. In this case, the light diffusion unit 140 is configured such that the representative length is equal to or less than the light radius h in the light diffusion unit 140.

  Note that the laser light source unit 100 and the condensing optical unit 130 are configured such that the radius of light on the emission side from the light diffusion unit 140 is h. Therefore, the laser light source unit 100 may include an optical component such as a lens or a curved mirror (not shown).

  FIG. 5 is a diagram illustrating a configuration example of the video display device 2 according to the first embodiment. In the present embodiment, since the size of the video display device 2 itself is reduced with respect to the projection distance, the optical magnification (b / a) is increased. Therefore, the light radius h in the light diffusion unit 140 is smaller than the light radius H on the screen 3.

  In the configuration example 2 shown in FIG. 5, since the effective radius r of the scanning unit 120 is smaller than that in the configuration example 1, the light radius R in the imaging optical unit 150 is made smaller than that in the configuration example 1. Therefore, in the configuration example 2, the distance a from the light diffusing unit 140 to the imaging optical unit 150 is configured to be smaller than that in the configuration example 1. That is, the optical magnification (b / a) of Configuration Example 2 is larger than that of Configuration Example 1. For this reason, the light radius h in the light diffusing unit 140 is configured to be smaller than that in the first configuration example.

  According to the present embodiment, the light diffused by the light diffusing unit 140 reaches the screen 3 while preventing leakage of light from the effective radii of the imaging optical unit 150 and the scanning unit 120. Therefore, the light use efficiency is improved. Further, since the diffused light can be narrowed down, it is possible to display the high-quality video 11 on the screen 3.

  Further, the light emitted from the laser light source unit 100 is given a phase by the phase applying unit 110 and is scanned on the screen 3 by the scanning unit 120. Therefore, speckles with respect to the image 11 displayed on the screen 3 can be reduced.

  <Modification>

  Next, a modification of the first embodiment will be described. FIG. 6 is a diagram for explaining a light diffusing unit 140 in a modification of the first embodiment. Hereinafter, differences from the above-described embodiment will be described. The light diffusing unit 140 in the modification is configured to disturb the polarization.

  FIG. 6A is a diagram illustrating an example of the light diffusion unit 140 according to the modification. The light diffusing unit 140 includes a transmissive diffusion plate 142 that disturbs polarization in place of the transmissive diffusing member 141 or in addition to the transmissive diffusing member 141. The diffusion plate 142 is, for example, a transmission type volume diffusion plate. The diffusion plate 142 has the property of diffusing the incident light and randomizing the polarization of the diffused light even when a single polarized light is incident.

  Accordingly, this is a case where the laser light source unit 100 outputs light having substantially single polarized light, and the condensing optical unit 130, the imaging optical unit 150, and the scanning unit 120 are configured to substantially maintain polarized light. However, by using the diffusion plate 142, the polarization of the light output from the video display device 2 is not single. Thereby, the speckle reduction effect by multiplexing of polarized light can be obtained.

  FIG. 6B is a diagram illustrating another example of the light diffusion unit 140 according to the modification. The light diffusing unit 140 includes a transmissive composite wavelength plate 143 instead of the transmissive diffusing member 141 or in addition to the transmissive diffusing member 141. The composite wave plate 143 is a wave plate in which a plurality of wave plates having different polarization axes are arranged two-dimensionally (on the same plane).

  FIG. 6C is a diagram for explaining polarization by the composite wave plate 143. In the composite wave plate 143, as shown in FIG. 6C, two types of wave plates whose polarization axes are shifted by 45 degrees are arranged in a lattice shape. Since a plurality of wave plates having different polarization axes are arranged two-dimensionally, light is diffracted and spread and output. Thereby, the composite wave plate 143 exhibits a function of diffusing light.

  When light having a single polarization is incident on the composite wave plate 143, a plurality of lights having different polarizations are output by the wave plates having different polarization axes. Therefore, it is possible to obtain a speckle reduction effect due to polarization multiplexing.

  <Second Embodiment>

  FIG. 7 is a diagram illustrating a configuration example of the phase applying unit 110 according to the second embodiment. The phase applying unit 110 according to the second embodiment is partially common to the phase applying unit 110 according to the first embodiment, and is partially different. Hereinafter, differences from the first embodiment will be described. The phase applying unit 110 in the second embodiment includes a light diffusion unit driving unit 200. In addition, the phase applying unit 110 in the second embodiment includes a movable light diffusing unit 140 </ b> A instead of the light diffusing unit 140. The light diffusion unit driver 200 drives the movable light diffusion unit 140A.

  The light diffusion unit driving unit 200 includes a driving element (not shown) such as a motor, and drives the movable light diffusion unit 140A. The light diffusion unit driver 200 vibrates or rotates the movable light diffusion unit 140A, for example. The movable light diffusing unit 140A includes a transmissive diffusing member 141, similarly to the diffusing unit in the first embodiment. The transmissive diffusing member 141 may not disturb the polarization of incident light, or may disturb the polarization. The movable light diffusing unit 140 </ b> A differs from the light diffusing unit 140 only in that it is driven by the light diffusing unit driving unit 200.

  It is preferable that the movable light diffusing unit 140A is driven in a plane substantially perpendicular to the light incident on the movable light diffusing unit 140A. Specifically, the movable light diffusing unit 140A is preferably driven vertically and horizontally while maintaining a state perpendicular to the incident light, that is, with the incident light being a normal line. Moreover, it is preferable that the movable light diffusing unit 140A rotates about a line parallel to the incident light as a central axis.

  Thereby, the light passing through the movable light diffusing unit 140A while maintaining the distance from the condensing optical unit 130 to the movable light diffusing unit 140A and the distance from the movable light diffusing unit 140A to the imaging optical unit 150. It is possible to provide a phase that changes with time. In addition, maintaining the distance from the condensing optical unit 130 to the movable light diffusing unit 140A and the distance from the movable light diffusing unit 140A to the imaging optical unit 150 can maintain the resolution of the image 11 to be displayed. Means you can.

  Note that the drive frequency of the movable light diffusing unit 140A is preferably configured so as not to be approximately an integral multiple or approximately a half integer multiple of the scan frequency in the y direction shown in FIG. Thereby, it is possible to make it difficult to visually recognize the disturbance of the image 11 such as brightness unevenness due to the beat of the drive of the movable light diffusing unit 140A and the light scanning by the scanning unit 120.

  Further, the movable light diffusion portion 140A is the same as the first embodiment in that it may include a plurality of transmission type diffusion members 141. In this case, the light diffusion unit driving unit 200 may drive one transmission type diffusion member 141 or may drive a plurality of transmission type diffusion members 141. Further, when driving a plurality of transmission type diffusing members 141, if the driving phases and loci are driven differently, the driving amplitude and frequency can be reduced.

  According to the present embodiment, a time-varying phase can be given to the light passing through the movable light diffusing unit 140A. Thereby, since the speckle pattern produced | generated on a user's retina changes with time, generation | occurrence | production of a speckle can be suppressed by the time integration of a speckle pattern.

  <Third Embodiment>

  FIG. 8 is a diagram illustrating a configuration example of the phase applying unit 110 according to the third embodiment. The phase applying unit 110 according to the third embodiment is partially shared by the phase applying unit 110 according to the first and second embodiments, and is partially different. Hereinafter, differences from the first and second embodiments will be described.

  The phase adding unit 110 according to the third embodiment includes a light branching unit 210, an objective optical unit 220, a light diffusing unit 230, and an imaging optical unit 240. The light branching unit 210 separates an optical path that travels from the laser light source unit 100 toward a light diffusing unit 230 described later and an optical path that travels from the light diffusing unit 230 toward the screen 3. The light branching unit 210 branches light by, for example, the polarization of incident light. The light branching unit 210 branches the light incident from the light diffusing unit 230 via the objective optical unit 220 and guides it to the imaging optical unit 240 described later.

  The light branching unit 210 includes a polarization branching element 211 and a λ / 4 wavelength plate 213. The polarization branching element 211 has a surface 212 that allows light of predetermined polarization to pass therethrough and reflects light of polarization different from the predetermined polarization. The polarization branching element 211 is, for example, a polarization beam splitter. The surface 212 of the polarization splitting element 211 transmits, for example, P-polarized light and reflects S-polarized light. The λ / 4 wavelength plate 213 converts linearly polarized light and circularly polarized light into each other. The polarization splitting element 211 includes a first surface 211a positioned on the laser light source unit 100 side, a second surface 211b facing the first surface 211a and positioned on the objective optical unit 220 side, a first surface 211a, and It has the 3rd surface 211c orthogonal to the 2nd surface 211b.

  The objective optical unit 220 collects the light incident from the light branching unit 210. The objective optical unit 220 guides light incident from the light diffusion unit 230 described later to the light branching unit 210. In the objective optical unit 220, for example, the main axis is parallel to the normal line of the light diffusion unit 230, and the optical axis of the light incident from the light branching unit 210 is substantially equal to the main axis. The objective optical unit 220 emits substantially parallel light (collimated light) when the light incident from the light diffusing unit 230 is emitted to the light branching unit 210.

  The light diffusion unit 230 includes at least one reflective diffusion member 231 and diffuses incident light. The reflective diffusion member 231 is, for example, a reflective diffusion plate that does not substantially disturb the polarization of incident light. In other words, the reflection-type diffusing member 231 has a substantially single polarization of the reflected light when light of a single polarization is incident. For example, when clockwise circularly polarized light is incident on the reflective diffusing member 231, the polarized light of the reflected light becomes substantially counterclockwise circularly polarized light.

  For example, the reflection type diffusion member 231 provided in the light diffusion unit 230 is a reflection type surface diffusion plate or a reflection type diffraction element. Further, the light diffusing unit 230 may include a plurality of reflective diffusion members 231. The installation position of the light diffusing unit 230 is within a range where light emitted from the objective optical unit 220 is condensed.

  The imaging optical unit 240 forms an image on the screen 3 using the light diffused by the light diffusing unit 230. The imaging optical unit 240 includes a lens 241 that receives the light branched by the light branching unit 210.

  In the present embodiment, the laser light source unit 100 emits substantially single polarized light. In the following description, it is assumed that the laser light source unit 100 emits substantially P-polarized light only. The light emitted from the laser light source unit 100 reaches the phase applying unit 110 and enters the first surface 211 a of the polarization branching element 211 included in the light branching unit 210. In the present embodiment, the surface 212 of the polarization splitting element 211 transmits P-polarized light and reflects S-polarized light.

  Since the light incident on the polarization branching element 211 from the laser light source unit 100 is substantially P-polarized light, it passes through the surface 212 and is emitted from the second surface 211 b of the polarization branching element 211. The emitted light is incident on the λ / 4 wavelength plate 213. The λ / 4 wavelength plate 213 converts substantially incident P-polarized light into circularly-polarized light. The λ / 4 wavelength plate 213 emits, for example, substantially clockwise circularly polarized light to the objective optical unit 220 from a surface opposite to the incident surface.

  The emitted light is collected on the light diffusion unit 230 by the objective optical unit 220. The light diffusion unit 230 diffuses and emits the incident light. Since substantially clockwise circularly polarized light is incident on the light diffusing unit 230, the light diffusing unit 230 emits substantially counterclockwise circularly polarized light. The objective optical unit 220 receives light from the light diffusion unit 230.

  The objective optical unit 220 is preferably composed of an optical component having a high numerical aperture in order to capture more light diffused by the light diffusing unit 230, like the imaging optical unit 150 in the first embodiment. . For example, the objective optical unit 220 preferably has a numerical aperture of approximately sin θ or more, where θ is the half angle of the spread angle of the light diffused by the light diffusion unit 230. Thereby, it can suppress that the light radiate | emitted from the light-diffusion part 230 leaks out of the objective optical part 220, and can improve the utilization efficiency of light.

  In addition, the objective optical unit 220 is preferably composed of an optical system or an optical component with good light collecting performance in order to generate the high-quality image 11 on the screen 3. For example, the lens 221 used in the objective optical unit 220 is a plano-convex lens in which the light diffusion unit 230 side is flat, a meniscus lens in which the light diffusion unit 230 side is concave, or an aspheric lens.

  The light emitted from the objective optical unit 220 reaches the phase adding unit 110 and enters the λ / 4 wavelength plate 213. Since the objective optical unit 220 maintains polarization, the polarization of light incident on the λ / 4 wavelength plate 213 is substantially counterclockwise circularly polarized light emitted from the light diffusion unit 230. The λ / 4 wavelength plate 213 converts the incident substantially left-handed circularly polarized light into linearly polarized light, for example, substantially S-polarized light, and emits it.

  The polarization splitting element 211 enters the light emitted from the λ / 4 wavelength plate 213. Since the incident light is substantially S-polarized light, it is reflected by the surface 212 and is emitted from the third surface 211c perpendicular to the second surface 211b. In other words, the polarization branching element 211 branches the light incident from the λ / 4 wavelength plate 213 and guides it to the imaging optical unit 240. The light emitted from the polarization splitting element 211 enters the imaging optical unit 240 and is emitted from the imaging optical unit 240 to the scanning unit 120. The imaging optical unit 240 forms an image on the screen 3 using the emitted light.

  Next, the installation conditions of the video display device 2 in the present embodiment will be described with reference to FIG. 4 because the installation conditions are partially in common with the video display device 2 in the first embodiment. In the present embodiment, the light emitted from the laser light source unit 100 is condensed on the light diffusion unit 230 by the objective optical unit 220. This is similar to the point that the light emitted from the laser light source unit 100 is condensed on the light diffusion unit 230 by the condensing optical unit 130 in the first embodiment.

  In the present embodiment, the objective optical unit 220 and the imaging optical unit 240 generate an image of the object surface on the screen 3 using the light diffusion unit 230 as the object surface. In the first embodiment, this corresponds to the imaging optical unit 240 generating an image of the object surface on the screen 3 with the light diffusing unit 230 as the object surface.

  The optical system that is determined from the optical elements constituting the objective optical unit 220 and the imaging optical unit 240 and the optical distance between them is defined as a composite imaging optical unit 150A. That is, the composite imaging optical unit 150 </ b> A includes the objective optical unit 220 and the imaging optical unit 240. In the present embodiment, FIG. 4 shows an optical system in which the composite imaging optical unit 150A generates an image of the object surface on the screen 3 with the light diffusion unit 230 as the object surface. In FIG. 4, a is a distance from the light diffusing unit 230 to the front plane (light diffusing unit 230 side) main plane of the composite imaging optical unit 150A, and b is a main side on the rear side (scanning unit 120 side) of the composite imaging optical unit 150A. A distance from the plane to the screen 3, R is a radius of light of the composite imaging optical unit 150A when the objective optical unit 220 and the imaging optical unit 240 are replaced with the composite imaging optical unit 150A.

  The composite imaging optical unit 150A is configured to receive light having a diameter equal to or smaller than a value obtained by extrapolating the beam diameter on the screen 3 serving as a projection surface and the effective radius in the scanning unit 120 using the distance c and the distance b. The That is, the light radius H on the screen 3 and the effective radius r on the scanning unit 120 are extrapolated using the distance c from the screen to the scanning unit 120 and the distance b from the screen to the main plane of the composite imaging optical unit 150A. Light having a radius equal to or smaller than the value is incident on the composite imaging optical unit 150A. In other words, the radius R of the light incident on the composite imaging optical unit 150A satisfies the following condition.

  R ≦ {(r−H) × b / c} + H

  Similarly to the first embodiment, in order to set the radius of the light on the screen 3 to H, the radius h of the light emitted from the light diffusing unit 230 is obtained by dividing H by the optical magnification (b / a). The video display device 2 is configured to be substantially equal to or less than the value.

  The spread angle of the light diffused by the light diffusing unit 230 is a half angle θ, and the light in the composite image forming optical unit 150A when the light diffused by the light diffusing unit 230 reaches the composite image forming optical unit 150A. The radius R can be expressed as h + a × tan θ. Therefore, the video display device 2 is configured to satisfy the following conditions.

  h + a × tan θ ≦ {(r−H) × b / c} + H

  The laser light source unit 100 and the condensing optical unit 130 are configured such that the radius of light on the emission side from the light diffusion unit 230 is h. Therefore, the laser light source unit 100 may include an optical component such as a lens or a curved mirror (not shown).

  According to the present embodiment, it is possible to provide the video display device 2 with high light use efficiency and high image quality by reducing speckles. In addition, since a part of the optical path from the laser light source unit 100 to the screen 3 is shared, the video display device 2 can be reduced in size. In addition, since the objective optical unit 220 collects light and enters the diffused light into the light diffusing unit 230, the installation difficulty level can be reduced as compared with the case where many optical components are used.

  In other words, the objective optical unit 220 emits substantially parallel light to the light branching unit 210, and the light branching unit 210 guides the substantially parallel light to the imaging optical unit 240. The image optical unit 150A can be configured, which can contribute to a reduction in installation difficulty.

  <Fourth Embodiment>

  FIG. 9 is a diagram illustrating a configuration example of the phase applying unit 110 according to the fourth embodiment. Hereinafter, differences from the first, second, and third embodiments will be described. In the present embodiment, the phase adding unit 110 has optical axes in which incident light to the light diffusing unit 230 and outgoing light from the light diffusing unit 230 are different.

  The light branching unit 210 includes a reflection mirror 214 in place of the polarization branching element 211 and the λ / 4 wavelength plate 213 in the third embodiment. The reflection mirror 214 reflects either one of the light incident from the laser light source unit 100 and the light incident from the objective optical unit 220. When reflecting the light incident from the objective optical unit 220, the reflection mirror 214 guides the reflected light to the imaging optical unit 240.

  The objective optical unit 220 includes a lens 221, and the optical axis of light incident on the objective optical unit 220 from the laser light source unit 100 via the light branching unit 210 is different from the main axis of the lens 221. . Note that the optical axis of the light incident on the objective optical unit 220 from the laser light source unit 100, the main axis of the lens 221, and the normal line of the reflective diffusion member 231 included in the light diffusion unit 230 are preferably parallel.

  That is, the phase adding unit 110 in the fourth embodiment includes an optical axis of light incident on the objective optical unit 220 from the laser light source unit 100 and an optical axis of light incident on the optical branching unit 210 from the objective optical unit 220. It is comprised so that the position may differ.

  In the present embodiment, the light emitted from the laser light source unit 100 passes through the light branching unit 210 and enters the objective optical unit 220. The light emitted from the objective optical unit 220 is reflected by the light diffusing unit 230, diffuses, and enters the objective optical unit 220 again. The light emitted from the objective optical unit 220 is reflected by the reflection mirror 214, enters the scanning unit 120, and scans on the screen 3.

  The light diffusing unit 230 may include a reflective diffusion device that does not substantially disturb polarized light, or may include a reflective diffusion member 231 that disturbs polarized light. By using the light diffusing unit 230 including the reflective diffusing member 231 that disturbs the polarized light, it is possible to obtain a speckle reduction effect by multiplexing the polarized light.

  Further, it has been described that the light emitted from the objective optical unit 220 is reflected by the reflection mirror 214 and enters the imaging optical unit 240, but the present embodiment is not limited to this. For example, the light emitted from the laser light source unit 100 to the phase applying unit 110 may be reflected by the reflection mirror 214 and incident on the objective optical unit 220. Thereafter, the light emitted from the objective optical unit 220 is reflected by the light diffusing unit 230, reenters the objective optical unit 220, and then enters the imaging optical unit 240 without being reflected by the reflection mirror 214. May be.

  Alternatively, the light branching unit 210 may include a plurality of reflection mirrors 214 and reflect each of the light emitted from the laser light source unit and the light emitted from the objective optical unit 220.

  According to the present embodiment, the video display device 2 can be further simplified as compared with the case where the polarization splitting element 211 and the wave plate are used. In addition, the video display device 2 that displays the high-quality video 11 can be provided by the speckle reduction effect by the light diffusion unit 230. Moreover, the light utilization efficiency can be improved by appropriately installing the composite imaging optical unit 150A.

  As mentioned above, although each embodiment and modification which concern on this invention have been demonstrated, this invention is not limited to an example of above-described embodiment, Various modifications are included. For example, the above-described exemplary embodiment has been described in detail for easy understanding of the present invention, and the present invention is not limited to the one having all the configurations described here. A part of the configuration of an example of an embodiment can be replaced with the configuration of another example. Moreover, it is also possible to add the structure of another example to the structure of an example of a certain embodiment. In addition, for a part of the configuration of an example of each embodiment, another configuration can be added, deleted, or replaced. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. In addition, the control lines and information lines in the figure indicate what is considered necessary for the description, and do not necessarily indicate all. It can be considered that almost all configurations are connected to each other.

  In addition, the configuration of the above-described video display device can be classified into more components according to the processing content. Moreover, it can also classify | categorize so that one component may perform more processes.

1: video display system, 2: video display device, 3: screen, 11: video, 100: laser light source unit, 101: laser light source, 110: phase applying unit, 120: scanning unit, 121: scanning element, 130: collection Optical optic section 131: Condensing lens 140/230: Light diffusing section 140A: Movable light diffusing section 141: Transmission type diffusing member 142: Diffusing plate 143: Compound wavelength plate 150/240: Imaging Optical part, 150A: Composite imaging optical part, 151/221/241: Lens, 200: Light diffusion part driving part, 210: Light branching part, 211: Polarization branching element, 212: Surface, 213: λ / 4 wavelength plate , 214: reflection mirror, 220: objective optical unit, 231: reflection type diffusing member

Claims (15)

A laser light source that emits laser light;
A condensing optical unit that condenses the light emitted from the laser light source unit;
A transmissive light diffusing unit for diffusing light from the condensing optical unit;
An imaging optical unit that forms an image on the projection surface using the light diffused by the light diffusion unit;
A scanning unit that scans light from the imaging optical unit onto the projection surface,
The imaging optical unit has a beam diameter on the projection surface and an effective diameter on the scanning unit as a first distance from the projection surface to the scanning unit and a second distance from the projection surface to the imaging optical unit. An image display device, wherein light having a diameter equal to or smaller than a value extrapolated using a distance is incident. The video display device according to claim 1,
The image display device according to claim 1, wherein the imaging optical unit has a numerical aperture equal to or greater than sin θ, where θ is a half angle of a spread angle of light emitted from the light diffusion unit. The video display device according to claim 1,
The image display device according to claim 1, wherein the light diffusing unit has a representative length of a diffusion pattern equal to or less than a radius of light incident from the condensing optical unit. A laser light source that emits laser light;
A light branching part for branching the laser light;
An objective optical unit that condenses the light that has passed through the light branching unit;
A reflective light diffusing unit that diffuses light from the objective optical unit;
An imaging optical unit that forms an image on the projection surface using the light diffused by the light diffusion unit;
A scanning unit that scans light from the imaging optical unit onto the projection surface,
The image display device, wherein the light branching unit guides light from the light diffusion unit to the imaging optical unit. The video display device according to claim 4,
The image display apparatus, wherein the objective optical unit receives light from the light diffusion unit and emits substantially parallel light. The video display device according to claim 4,
A composite imaging optical unit including the objective optical unit and the imaging optical unit;
The synthetic imaging optical unit has a beam diameter on the projection surface and an effective diameter on the scanning unit, a first distance from the projection surface to the scanning unit, and a first distance from the projection surface to the synthetic imaging optical unit. An image display apparatus, wherein light having a diameter equal to or smaller than an extrapolated value using a distance of 2 is incident. The video display device according to claim 4,
The image display device according to claim 1, wherein the objective optical unit has a numerical aperture equal to or greater than sin θ, where θ is a half angle of a spread angle of light emitted from the light diffusion unit. The video display device according to claim 4,
The objective optical unit has a main axis parallel to a normal line of the light diffusing unit, and the main axis is substantially equal to an optical axis of light incident from the light branching unit. The video display device according to claim 4,
The light branching unit includes a polarization branching element and a λ / 4 wavelength plate,
The image display device, wherein the polarization splitting element branches light incident from a λ / 4 wavelength plate and guides it to the imaging optical unit. The video display device according to claim 4,
The optical branching unit includes a mirror that reflects either one of the light incident from the laser light source unit and the light incident from the objective optical unit, an optical axis of the light emitted to the objective optical unit, and the objective optical An image display device characterized in that the optical axis of light incident from the portion is different. The video display device according to claim 1,
The image display device, wherein the light diffusing unit is a transmissive surface diffusing plate or a transmissive diffraction grating, and does not substantially disturb polarized light from the condensing optical unit. The video display device according to claim 1,
The image display device, wherein the light diffusing unit includes an optical element including a transmission type volume diffusing plate or a plurality of wave plates having different polarization axes, and disturbs polarized light from the condensing optical unit. The video display device according to claim 1,
The light diffusing unit includes at least one diffusing member,
At least one of the diffusing members vibrates or rotates. The video display device according to claim 1,
The image display device according to claim 1, wherein the imaging optical unit includes a plano-convex lens in which the light diffusion unit side is flat, a meniscus lens in which the light diffusion unit side is concave, or an aspheric lens. A video display device according to claim 1 and a screen.
The video display device displays video using the screen as the projection plane,
The video display system, wherein the screen vibrates or rotates during video display.

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