JP5187183B2 - Scanning image display device - Google Patents

Description

  The present invention relates to a scanning image display apparatus.

  Conventionally, a projection-type projector is known as one of devices capable of displaying a large screen image. The projection type projector includes, for example, an illumination device, a spatial light modulation device, a projection lens, and the like. The light emitted from the illumination device is modulated by a spatial light modulation device such as a liquid crystal light valve, and then enlarged and projected by a projection lens. In such a projector, a large-screen image can be obtained more easily than a direct-view image display device, but it is difficult to reduce the size and weight of the device. This is because the plurality of lenses constituting the projection optical system are components having a high weight ratio in the apparatus, and are difficult to miniaturize from the viewpoint of securing the numerical aperture.

  A scanning projector (scanning image display device) has been proposed as an image display device that can display an image on a large screen and can be reduced in size and weight. In general, the scanning type includes a modulation circuit, a laser light source, and a scanning optical system. The modulation circuit modulates light emitted from the laser light source based on an image signal supplied from a signal source such as a PC. The scanning optical system has movable mirrors such as a horizontal deflection mirror and a vertical deflection mirror. These movable mirrors are driven based on an image signal supplied from a signal source such as a PC. The light emitted from the laser light source has its optical axis changed over time by the movable mirror of the scanning optical system, and scans the surface to be scanned such as a screen to draw an image.

  In such a scanning type, the number of optical components such as lenses can be reduced as compared with an illumination optical system using a lamp light source or the like. In addition, since light having a desired gradation can be generated by the modulation circuit, a modulation device such as a liquid crystal light valve becomes unnecessary. Further, the projection optical system can be simplified or omitted. As described above, the configuration can be greatly simplified, and the apparatus can be reduced in size and weight to the extent that it can be portable.

  By the way, it is known that speckle noise is likely to occur in an image formed by laser light due to the coherence of the laser light. When speckle noise is visually recognized, the image quality deteriorates, so it is extremely important to take measures against speckle noise. A technique for reducing speckle noise is proposed in Patent Document 1.

The image generation apparatus disclosed in Patent Literature 1 forms an intermediate image for each of a plurality of color lights emitted from a light source. A light scattering portion (diffraction grating) is disposed at the formation position of the intermediate image. Light from the plurality of intermediate images travels in the direction corresponding to the wavelength by the diffraction grating and is projected onto the screen by the scanning optical system and the projection optical system. The light projected from the plurality of intermediate images differs in the projected position by the plurality of color lights. When attention is paid to one area on the screen, a plurality of colored lights having different times emitted from the light source are superimposed with a time difference. As a result, speckle noise is averaged over time and is not easily recognized.
JP2008-8877

  Although it is considered that speckle noise can be reduced by using the technique of Patent Document 1, the advantage of the scanning type is lost because the projection optical system that is originally unnecessary for the scanning type is provided. . For example, since it is difficult to reduce the size and weight of the apparatus as described above, it cannot be expected to have portability and cannot be used for a wide range of applications.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a scanning projector having a simple configuration and reduced speckle noise.

  The scanning image display device according to the present invention includes a light source device that emits light and light emitted from the light source device to form a secondary light source image, and light that diffuses and emits incident light. A diffusing element; a displacement mechanism for displacing the light diffusing element; a condensing / parallelizing optical system for condensing or collimating light emitted from the light diffusing element; and an emitting from the condensing / parallelizing optical system And a scanning optical system that scans the emitted light.

  In this way, the light from the secondary light source image formed on the light diffusing element by the light source device is diffused by the light diffusing element and emitted. The light emitted from the light diffusing element is condensed or collimated by the condensing / collimating optical system and is incident on the scanning optical system. The light incident on the scanning optical system is scanned (scanned) on the surface to be scanned by the scanning optical system. As the light diffusing element is displaced by the displacement mechanism, the diffusion pattern of light emitted from the light diffusing element changes, and the speckle pattern due to this light changes. Thereby, the speckle pattern is averaged and visually recognized as the entire displayed image, and speckle noise is hardly visually recognized. Further, since it is not necessary to re-image the light emitted from the light diffusing element between the light diffusing element and the surface to be scanned, there is no possibility that speckle noise is generated by re-imaging.

  According to the above configuration, a projection optical system is not required, and a scanning image display device capable of displaying an image with reduced speckle noise while having a simple configuration. By not using the projection optical system, the image quality is not deteriorated due to the aberration in the projection optical system, so that a scanning image display device capable of obtaining a high-quality image is obtained. In addition, since the light diffusing element is arranged at the position where the secondary light source image is formed, a small light diffusing element can be used, and an increase in size and weight of the scanning image display apparatus can be avoided.

In addition, an image forming optical system that forms an image of light emitted from the light source device on the light diffusing element may be included. In this case, it is preferable that the F value of the condensing / collimating optical system is smaller than the F value of the imaging optical system.
If the imaging optical system is included, the secondary light source image is reliably formed by the light emitted from the light source device. The light emitted from the light diffusing element has a larger diffusion angle than the light incident on the light diffusing element. If the F value of the condensing / collimating optical system is smaller than the F value of the imaging optical system, almost the entire light emitted from the light diffusing element enters the condensing / collimating optical system. This eliminates the waste of light.

  The light diffusing element may be a diffractive optical element. In this case, the light diffusion element may have different diffusion coefficients in two directions that are not parallel to each other in a direction along the light incident surface.

  In general, light incident on a diffractive optical element is emitted after being divided into a plurality of diffracted lights having different diffraction angles. Since the diffusion angle of the plurality of diffracted lights as a whole is larger than the light before entering the diffractive optical element, the diffractive optical element can function as a light diffusing element. If the light diffusing element is composed of a diffractive optical element, the diffusion angle can be controlled with high accuracy. In addition, the diffusion coefficient in two non-parallel directions among the directions along the light incident surface in the light incident surface in the light diffusing element can be controlled independently of each other, and emitted from the light diffusing element. The shape of the light beam in the cross section orthogonal to the optical axis of the light to be adjusted can be adjusted. Thereby, the utilization efficiency of the light in a condensing and collimating optical system can be improved. In addition, the shape of the pixel of the displayed image can be adjusted, and the image quality can be improved.

The displacement mechanism may be configured to rotate the light diffusing element in a plane whose normal direction is a direction non-parallel to the optical axis of light incident on the light diffusing element.
In this way, the mechanical mechanism can be simplified as compared with the translational movement of the light diffusing element. Further, by rotating the light diffusing element about an axis passing through the center of gravity of the light diffusing element, it is possible to eliminate the apparatus shake caused by the displacement of the light diffusing element.

The displacement mechanism may be configured to translate the light diffusing element in a plane substantially orthogonal to the optical axis of the light incident on the light diffusing element.
In this way, the angle between the predetermined direction in the light incident surface of the light diffusing element and the optical axis of the incident light does not change even if the light diffusing element is displaced, and the light diffusing element in the predetermined direction Can be controlled independently of the displacement of the light diffusing element.

  In addition, a plurality of light source devices that are provided corresponding to each of a plurality of color lights having different wavelength ranges and emit corresponding color light; and an optical path between each of the plurality of light source devices and the light diffusing element. And a light combining element configured to combine a plurality of color lights emitted from the plurality of light source devices.

  In this way, a plurality of color lights are combined by the light combining element, and an image is formed by the combined light, so that a color image can be displayed. The light synthesized by the light synthesizing element changes its diffusion pattern by passing through the light diffusing element, and the speckle pattern due to this light changes. Thereby, the speckle pattern is averaged and visually recognized as the entire displayed image, and speckle noise is hardly visually recognized.

The light combining element may be a prism in which an incident end face on which the plurality of colored lights are incident and an exit end face on which the plurality of colored lights are emitted are arranged non-parallel to each other.
In this way, the plurality of color lights can be synthesized by the aberration of the plurality of color lights being different from each other in the prism. If the light synthesizing element is configured by the prism, the image forming apparatus can be manufactured at a lower cost than the case where the light synthesizing element is configured by the dichroic prism or the diffractive optical element.

  The light combining element may be a diffractive optical element. In this case, the light combining element may have different diffusion coefficients in two directions that are not parallel to each other in a direction along the light incident surface.

  In this way, the diffractive optical element can synthesize a plurality of color lights because the diffraction angles of the plurality of color lights are different from each other. If the photosynthetic element is composed of a diffractive optical element, the diffusion angle can be controlled with high accuracy. In addition, the diffusion coefficient in two non-parallel directions among the directions along the light incident surface in the light incident surface in the light diffusing element can be controlled independently of each other, and emitted from the light diffusing element. The shape of the light beam in the cross section orthogonal to the optical axis of the light to be adjusted can be adjusted. Thereby, it is possible to improve the light utilization efficiency and improve the image quality.

  A plurality of light source devices which are provided corresponding to each of a plurality of color lights having different wavelength ranges, and which emit the corresponding color light and form the secondary light source images at different positions in the light diffusing element; It may be configured to include.

  In this way, since the secondary light source images corresponding to each of the plurality of color lights are formed at different positions in the light diffusing element, the light from the plurality of secondary light source images is at different positions on the scanned surface. To form an image. By emitting the color light of the gradation corresponding to the pixel at the imaging position on the surface to be scanned to the light source device, a plurality of color lights are superimposed and viewed at each pixel, and a color image can be displayed. According to the above configuration, since the light combining element is not necessary, it is possible to avoid an increase in size and weight of the scanning image display device.

  Hereinafter, although embodiment of this invention is described, the technical scope of this invention is not limited to the following embodiment. In the following description, various structures are illustrated using drawings, but in order to show the characteristic parts of the structures in an easy-to-understand manner, the structures in the drawings are shown in different sizes and scales from the actual structures. There is.

[First Embodiment]
FIG. 1 is a schematic diagram illustrating a schematic configuration of a projector (scanning image display apparatus) 1 according to the first embodiment, and FIG. 2 is a diagram schematically illustrating a light path in the projector 1.

  As shown in FIG. 1, the projector 1 includes an image signal processing system 10, a laser light source (light source device) 11, an imaging lens (imaging optical system) 12, a diffusion plate (light diffusion element) 13, a rotation mechanism (displacement mechanism). ) 14, a condensing lens (condensing / collimating optical system) 15, and a scanning optical system 16. The light used for image display in the projector 1 travels along the system optical axis 1A. The projector 1 generally operates as follows.

  An electric signal supplied from a signal source 8 such as a PC is processed by the image signal processing system 10 and transmitted to the laser light source 11 and the scanning optical system 16. The laser light source 11 emits light corresponding to the electrical signal, and this light is condensed by the imaging lens 12 to form a secondary light source image on the diffusion plate 13. Light from the secondary light source image is incident on the scanning optical system 16 while being condensed by the condenser lens 15. The light incident on the scanning optical system 16 is emitted by the scanning optical system 16 in the direction corresponding to the electric signal, and forms an image on the surface to be scanned 9 such as a wall or a screen. As the light emitted from the scanning optical system 16 scans the surface 9 to be scanned, the imaging position of this light changes with time, and an image is drawn (formed) on the surface 9 to be scanned. As for the light from the secondary light source image, the speckle noise in the image is reduced as the diffusion pattern changes with time as the diffusion plate 13 is displaced. Hereinafter, the components of the projector 1 will be described in detail.

  The image signal processing system 10 includes an interface 101, an image signal processing circuit 102, a modulation circuit 103, a timing generation circuit 104, and a mirror drive circuit 105. The interface 101 receives an electrical signal including an image signal and a synchronization signal from the signal source 8 and separates the electrical signal into an image signal and a synchronization signal. The separated image signal is transmitted to the image signal processing circuit 102, and the separated synchronization signal is transmitted to the timing generation circuit 104.

  The timing generation circuit 104 generates a timing signal indicating the display timing for each pixel for a plurality of pixels included in the image according to the resolution, switching speed (frame rate), scanning method, and the like of the image. For example, it is assumed that pixel data such as gradations in the electrical signal supplied from the signal source 8 are arranged for a scanning method that repeats scanning toward one side in the main scanning direction (for example, the horizontal direction). The scanning optical system 16 is assumed to be a scanning system that alternately performs scanning toward one side in the main scanning direction and scanning toward the other side. In such a case, it is necessary to invert the arrangement of the pixel data for each scanning with respect to the electric signal supplied from the signal source 8. With the timing signal, the image signal supplied from the signal source 8 can be converted into a format consistent with the scanning method of the projector 1. The generated timing signal is transmitted to the image signal processing circuit 102 and the mirror driving circuit 105. The mirror drive circuit 105 outputs the drive amounts of the first deflection mirror 161 and the second deflection mirror 162 constituting the scanning optical system 16 to the scanning optical system 16 based on the timing signal.

  The image signal processing circuit 102 performs various kinds of image processing such as gamma processing on the image signal, and based on the timing signal so that the pixel data included in the image signal is transmitted to the modulation circuit 103 in time-sequential scanning. Adjust the image signal. For example, pixel data such as gradation is stored in a frame buffer for a plurality of pixels included in an image for one frame, and the pixel data is read sequentially in the scanning time and transmitted to the modulation circuit 103. For example, in the image signal received from the interface 101, when the pixel data is arranged in one direction in the main scanning direction, for example, the pixel data of a plurality of pixels corresponding to one scanning line is stored in the line memory. Keep it. The pixel data is read line by line for each scanning line, and the reading direction is reversed in the next scanning.

  The modulation circuit 103 adjusts the output of the laser light source 11 based on the image signal so that the intensity of the light emitted from the laser light source 11 changes with time according to the gradation for each pixel.

  The laser light source 11 includes a light source in which one or more laser elements are formed on a laser substrate or the like, a light source in which an excitation laser element is combined with a laser crystal, and the like. As the laser element, either a surface emitting laser element or an edge emitting laser element may be used. Although the detailed structure of the laser light source 11 of this embodiment is not illustrated, it is configured using a surface emitting laser element.

  As shown in FIG. 2, in this embodiment, the light L emitted from the laser light source 11 has a diffusion angle. The light L emitted from the laser light source 11 is incident on the imaging lens 12 with the beam diameter expanding, and is condensed by the imaging lens 12 and imaged on the diffusion plate 13.

  The light diffusing element emits incident light with an increased diffusion angle than before the incident light. In the light emitted from the light diffusing element, the proportion of the amount of light (wide angle component) in the portion away from the central axis of the light beam is larger than that before entering the light diffusing element. In the present embodiment, the light diffusing element employs a diffusing plate 13 that is a disc-shaped translucent member in which diffusing particles are dispersed. As the light diffusing element, various diffractive optical elements such as a volume amplitude type, a volume phase type, and a surface relief type can be used instead of the diffusing plate 13.

  Although the detailed structure of the rotation mechanism 14 of the present embodiment is not shown, the rotation mechanism 14 includes a support member and a motor. A support member supports the peripheral part of the diffusion plate 13 rotatably. The motor applies a moment to the diffusion plate 13 via the support member. When a moment is applied to the diffusion plate 13, the diffusion plate 13 rotates with the axis passing through the center of gravity as the rotation axis. About arrangement | positioning of a rotating shaft, it can set suitably according to the magnitude | size of the part (it calls here a translucent part) through which the light L passes in the diffusing plate 13. FIG. Here, the diffusion plate 13 and the rotation mechanism 14 are arranged so that the central axis of the diffusion plate 13 is shifted from the system optical axis 1A. Thereby, the distribution of the diffusing particles in the translucent part is surely changed as the diffusion plate 13 rotates.

  In addition, since the diffusion plate 13 has a finite thickness, the light transmission is performed on the downstream side or the upstream side along the system optical axis 1A with respect to the position where the beam diameter of the light L is minimized (imaging position). The part has a finite size. Since the distribution of the diffusing particles in the light transmitting portion only needs to change with the rotation of the diffusion plate 13, for example, when the size of the light transmitting portion is sufficiently larger than the size of the diffusing particles. The rotation axis of the diffusion plate 13 may substantially coincide with the system optical axis 1A.

  The light L emitted from the diffusing plate 13 can be regarded as light emitted from a point light source disposed at the center of gravity of the secondary light source image. Light L from the secondary light source image is collected by the condenser lens 15. The F value of the condenser lens 15 is smaller than the F value of the imaging lens 12. As a result, the entire light diffused by the diffusion plate 13 enters the condenser lens 15.

  As shown in FIG. 1, the scanning optical system 16 includes a first deflecting mirror 161 that changes the optical axis of incident light in the main scanning direction on the scanned surface 9, and sub-scanning the optical axis of incident light on the scanned surface 9. And a second deflecting mirror 162 that changes the direction. For example, the main scanning direction is a horizontal direction on the scanned surface 9, and the sub-scanning direction is a vertical direction orthogonal to the horizontal direction on the scanned surface 9. For example, the first deflection mirror 161 is configured by a micromechanical mirror formed by a MEMS technique or the like, and the second deflection mirror 162 is configured by a galvano mirror or the like.

  The first deflection mirror 161 is driven by a mirror driving unit (not shown). The mirror drive unit receives the drive amount from the mirror drive circuit 105, and rotates the first deflection mirror 161 around the predetermined rotation axis at an angular velocity and amplitude corresponding to the drive amount. As a result, the normal direction of the surface on which light is incident in the first deflecting mirror 161 changes with respect to the optical axis of the incident light L, and the optical axis of the light reflected by this surface changes according to the timing signal. . The second deflection mirror 162 is driven by a mirror driving unit in the same manner as the first deflection mirror 161. Here, the first deflection mirror 161 operates at its inherent resonance frequency. An image is drawn in both the scanning toward one side in the main scanning direction and the scanning toward the other side.

  In the projector 1 configured as described above, the diffusion pattern of the light L emitted from the diffusion plate 13 changes with time as the diffusion plate 13 is rotated by the rotation mechanism 14. Thereby, the speckle pattern by the light imaged on the to-be-scanned surface 9 changes with time. Therefore, the speckle pattern is visually averaged over time as the displayed image as a whole, and speckle noise becomes difficult to visually recognize. Further, since the light emitted from the diffusing plate 13 does not form an image between the diffusing plate 13 and the surface 9 to be scanned, speckle noise does not occur due to the image forming. As described above, the projector 1 according to the first embodiment is capable of displaying a high-quality image in which speckle noise is remarkably reduced while having a simple device configuration.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in that it includes a plurality of laser light sources (light source devices) and a dichroic prism (light combining element).

  FIG. 3 is a schematic diagram illustrating a schematic configuration of the projector 2 according to the second embodiment. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment. Detailed descriptions of the same components as those in the first embodiment may be omitted.

  As shown in FIG. 3, the projector 2 includes an image signal processing system 20, a plurality of laser light sources 21 r, 21 g, 21 b, and a dichroic prism 27. The laser light source 21r emits red color light Lr, the laser light source 21g emits green color light Lg, and the laser light source 21b emits blue color light Lb. The image signal processing system 20 of the second embodiment separates the image signal into a red signal, a blue signal, and a green signal, and each of the laser light sources 21r, 21g, and 21b based on the signals for each color. The output of is adjusted. Here, the modulation circuit adjusts the outputs of the laser light sources 21r, 21g, and 21b so that the color lights Lr, Lg, and Lb form one predetermined pixel at substantially the same timing.

  The color lights Lr, Lg, Lb emitted from the laser light sources 21 r, 21 g, 21 b are incident on the dichroic prism 27. The dichroic prism 27 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects the red color light Lr and a dielectric multilayer film that reflects the blue color light Lb are disposed on the inner surface of the dichroic prism 27 (the surface of the right-angle prism). The green color light Lg is emitted as it is without being reflected inside the dichroic prism 27. The color lights Lr and Lb are reflected by the dielectric multilayer film inside the dichroic prism 27 and emitted in substantially the same direction as the color light Lg. As described above, the color lights Lr, Lg, and Lb are combined into the light L, and the light L travels along the system optical axis 2A.

  The light L emitted from the dichroic prism 27 is imaged on the diffusion plate 13 by the imaging lens 12 to form a secondary light source image, as in the first embodiment. The light L from the secondary light source image is condensed by the condenser lens 15 and the optical axis is changed by the scanning optical system 16. As a result, a full color image is displayed on the scanned surface 9.

  In the projector 2 having the above-described configuration, the speckle noise is less likely to be visually recognized as the diffusion pattern of the light L emitted from the diffusion plate 13 changes with time as in the first embodiment. Yes. As described above, the projector 2 according to the second embodiment is capable of displaying a high-quality full-color image in which speckle noise is significantly reduced while having a simple device configuration.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment differs from the second embodiment in that the image signal processing system supplies signals corresponding to different pixels to a plurality of laser light sources, and the position of the secondary light source image by the plurality of laser light sources. There are a point that a plurality of laser light sources are arranged so as to deviate from each other and a point that does not include a color synthesizing element.

  FIG. 4 is a schematic diagram illustrating a schematic configuration of the projector 3 according to the third embodiment, and FIGS. 5A to 5C are conceptual diagrams schematically illustrating a laser light source driving method in the projector 3. 4 and 5, the same components as those of the second embodiment are denoted by the same reference numerals as those of the second embodiment. Detailed descriptions of the same components as those in the second embodiment may be omitted.

  As shown in FIG. 4, the projector 3 includes an image signal processing system 30. The image signal processing system 30 adjusts the output of each of the laser light sources 21r, 21g, and 21b. The color lights Lr, Lg, and Lb emitted from the laser light sources 21r, 21g, and 21b are imaged on the diffusion plate 13 by the imaging lens 12 to form a secondary light source image. The secondary light source images corresponding to the color lights Lr, Lg, and Lb are different from each other in the imaging position on the diffusion plate 13. The color lights Lr, Lg, and Lb from the secondary light source image are focused on the scanning surface 9 while being condensed by the condenser lens 15 and the optical axis is changed by the scanning optical system 16. Here, the imaging positions of the color lights Lr, Lg, and Lb on the scanned surface 9 are different from each other for the color lights Lr, Lg, and Lb.

As shown in FIG. 5A, the drive signal DR _X-2 is transmitted from the image signal processing system 30 to the laser light source 21r at a predetermined timing. The drive signal DG _X-1 is, for example, a voltage waveform, and the laser light source 21r emits color light Lr having a gradation corresponding to the power supplied by the drive signal DR _X-2 . On the scanned surface 9, a red pixel PR _X-2 is formed at the imaging position of the color light Lr. At the timing when the drive signal DR _X-2 is transmitted to the laser light source 21r, the drive signal DG _X-1 is transmitted to the laser light source 21g, and the drive signal DB _X is transmitted to the laser light source 21b. Thus, a green pixel PG _X-1 is formed at the imaging position of the colored light Lg, the blue pixel PB _X is formed on the imaging position of the color light Lb. Here, the pixels PR _X-2 , PG _X-1 and PB _X are arranged adjacent to each other along the scanning direction.

As shown in FIG. 5B, light (for example, light Lg) emitted from the scanning optical system 16 is a pixel (for example, pixel PR _X-2 ) located next to the pixel (for example, pixel PR _X-2 ) shown in FIG. For example, at the timing of scanning the pixel PG _X-1 ), the drive signal DR _X-1 is transmitted to the laser light source 21r. At the timing when the drive signal DR _X-1 is transmitted to the laser light source 21r, the drive signal DG _X is transmitted to the laser light source 21g, and the drive signal DB _{X + 1} is transmitted to the laser light source 21b. Thereby, the pixels PR _X−1 , PG _X , and PB _{X + 1} are formed at positions adjacent to each other along the scanning direction.

As shown in FIG. 5C, the light (for example, light Lg) emitted from the scanning optical system 16 is a pixel (for example, the pixel PR _X-1 ) located next to the pixel (for example, the pixel PR _X-1 ). For example, at the timing of scanning the pixel PG _X ), the drive signal DR _X is transmitted to the laser light source 21r. At the timing when the drive signal DR _X is transmitted to the laser light source 21r, the drive signal DG _{X + 1} is transmitted to the laser light source 21g, and the drive signal DB _{X + 2} is transmitted to the laser light source 21b. Thereby, the pixels PR _X , PG _{X + 1} , and PB _{X + 2} are formed at positions adjacent to each other along the main scanning direction.

In this way, the pixels PR _X , PG _X , and PB _X are formed at predetermined positions with a time difference, and the pixels PR _X , PG _X , and PB _X are superposed and viewed, thereby forming a full-color pixel. . By forming a plurality of full-color pixels, an image is formed by the plurality of pixels.

  The projector 3 having the above-described configuration is capable of displaying a high-quality full-color image in which speckle noise is remarkably reduced while having a simple device configuration. In addition, since the photosynthetic element can be omitted, it is possible to reduce the size and weight of the apparatus as compared with the second embodiment.

In the embodiment, the example in which the pixels PR _X-2 , PG _X-1 , and PB _X are arranged adjacent to each other along the scanning direction has been described. However, the imaging positions of the color lights Lr, Lg, and Lb are described. The amount of deviation may be twice or more the pixel size. Further, the imaging positions of the color lights Lr, Lg, and Lb may be shifted in the sub scanning direction, or may be shifted in the main scanning direction and the sub scanning direction. In any case, it is sufficient that the image signal processing system outputs a drive signal corresponding to the pixel to be formed at the imaging position.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. The fourth embodiment differs from the second embodiment in that a triangular prism is used as the light combining element instead of the dichroic prism, and a diffractive optical element is used as the light diffusing element instead of the diffusion plate. In this case, a moving mechanism is used as the displacement mechanism instead of the rotation mechanism.

  FIG. 6 is a schematic diagram illustrating a schematic configuration of the projector 4 according to the fourth embodiment. In FIG. 6, the same components as those of the second embodiment are denoted by the same reference numerals as those of the second embodiment. Detailed descriptions of the same components as those in the second embodiment may be omitted.

  As shown in FIG. 6, the projector 4 includes laser light sources 41 r, 41 g, 41 b, a triangular prism (light combining element) 47, a diffractive optical element (light diffusing element) 43, and a moving mechanism (displacement mechanism) 44. Yes.

  The laser light source 41r emits red color light Lr, the laser light source 41g emits green color light Lg, and the laser light source 41b emits blue color light Lb. Laser light sources 41r, 41g, and 41b are arranged so that the incident angles of the color lights Lr, Lg, and Lb with respect to the triangular prism 47 are different from each other. The incident angle of the colored light Lg with respect to the triangular prism 47 is larger than the incident angle of the colored light Lb with respect to the triangular prism 47. The incident angle of the colored light Lr with respect to the triangular prism 47 is larger than the incident angle of the colored light Lg with respect to the triangular prism 47.

  All of the laser light sources 41r, 41g, and 41b of the present embodiment are configured by edge-emitting laser elements. Although the detailed structure of the edge-emitting laser element is not shown, the active layer is disposed between a pair of electrodes. The light generated in the active layer travels in the surface direction of the active layer and is emitted. In general, the light emitted from the edge-emitting laser element has an elliptical shape in the cross section perpendicular to the optical axis. This ellipse has a major axis in the normal direction of the active layer and a minor axis in the surface direction of the active layer.

  In the triangular prism 47, the incident end faces on which the color lights Lr, Lg, and Lb are incident from the laser light sources 41r, 41g, and 41b are not parallel to the exit end faces from which the plurality of color lights are emitted. The color lights Lr, Lg, and Lb incident on the triangular prism 47 are combined due to the difference in aberration and emitted from the triangular prism 47. The synthesized light L travels along the system optical axis 4A. The light L has an elliptical shape in the cross section perpendicular to the system optical axis 4A. The light L is collected by the imaging lens 12 and forms an image on the diffractive optical element 43 to form a secondary light source image.

  The diffractive optical element 43 of this embodiment is configured by a volume holographic diffractive optical element. In the cross-sectional shape of the light beam (light L) before entering the diffractive optical element 43, the diffusion coefficient of the diffractive optical element 43 in the direction parallel to the major axis is larger than the diffusion coefficient of the diffractive optical element 43 in the direction parallel to the minor axis. It is getting smaller. Thereby, the light L emitted from the diffractive optical element 43 has a substantially perfect circular shape in the cross section perpendicular to the optical axis.

  The moving mechanism 44 includes, for example, a motor, a crank mechanism connected to the rotation shaft of the motor, a rod that connects the crank mechanism and the diffractive optical element 43, and the like. As the motor rotates, the rod translates the diffractive optical element 43 in a plane substantially orthogonal to the system optical axis 4A. The diffusion pattern of the light L emitted from the diffractive optical element 43 changes as the diffractive optical element 43 moves in parallel. Here, the moving mechanism 44 does not rotate the diffractive optical element 43 around the system optical axis 4A. Thereby, even if the diffractive optical element 43 is translated, the light L emitted from the diffractive optical element 43 hardly changes in the shape of the light beam in the cross section orthogonal to the optical axis.

  The light L from the secondary light source image is condensed by the condenser lens 15 and the optical axis is changed by the scanning optical system 16. As a result, a full color image is displayed on the scanned surface 9.

  The projector 4 having the above-described configuration is capable of displaying a high-quality full-color image in which speckle noise is remarkably reduced while having a simple device configuration. Further, since the cross-sectional shape of the light beam of the light L emitted from the diffractive optical element 43 is adjusted by the diffractive optical element 43, the light use efficiency in the condenser lens 15 is increased. In addition, the shape of the pixels formed on the scanned surface 9 can be adjusted by the diffractive optical element 43, thereby improving the image quality.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. The fifth embodiment differs from the fourth embodiment in that a diffractive optical element is employed as the light combining element instead of the triangular prism, and a diffusion plate is employed in the light diffusing element instead of the diffractive optical element. The point is that a rotation mechanism is employed as the displacement mechanism instead of the movement mechanism.

  FIG. 7 is a schematic diagram illustrating a schematic configuration of the projector 5 according to the fifth embodiment. In FIG. 7, the same components as those in the second and fourth embodiments are denoted by the same reference numerals as those in the second and fourth embodiments. Detailed description of the same components as those in the second and fourth embodiments may be omitted.

  As shown in FIG. 7, the projector 4 includes a diffractive optical element (photosynthesis element) 57. Each of the laser light sources 41r, 41g, and 41b is configured by an edge-emitting laser element, as in the fourth embodiment. The color lights Lr, Lg, and Lb emitted from the laser light sources 41r, 41g, and 41b all have an elliptical shape in the cross section perpendicular to the optical axis. The laser light sources 41r, 41g, and 41b are arranged so that the incident angles of the color lights Lr, Lg, and Lb with respect to the diffractive optical element 57 are different from each other. The incident angle of the color light Lg with respect to the diffractive optical element 57 is larger than the incident angle of the color light Lr with respect to the diffractive optical element 57. The incident angle of the colored light Lb with respect to the diffractive optical element 57 is further larger than the incident angle of the colored light Lg with respect to the diffractive optical element 57.

  The diffractive optical element 57 is a volume holographic diffractive optical element. The colored lights Lr, Lg, and Lb incident on the diffractive optical element 57 are diffracted at a diffraction angle corresponding to the wavelength, and are synthesized by having different diffraction angles. The synthesized light L is emitted from the diffractive optical element 57 and travels along the system optical axis 5A. The diffusion coefficient of the diffractive optical element 57 in the direction parallel to the major axis of the sectional shape of the light beam (light L) emitted from the diffractive optical element 57 is the diffusion coefficient of the diffractive optical element 57 in the direction parallel to the minor axis of the sectional shape. Is smaller than As a result, the light L emitted from the diffractive optical element 57 has a substantially perfect circular shape in the cross section perpendicular to the optical axis.

  The light L emitted from the diffractive optical element 57 forms an image on the diffusion plate 13 by the imaging lens 12 to form a secondary light source image, as in the second embodiment. The light L from the secondary light source image is condensed by the condenser lens 15 and the optical axis is changed by the scanning optical system 16. As a result, a full color image is displayed on the scanned surface 9.

  The projector 5 having the above-described configuration is capable of displaying a high-quality full-color image in which speckle noise is remarkably reduced while having a simple device configuration. Further, since the cross-sectional shape of the light beam in the light L emitted from the diffractive optical element 57 is adjusted by the diffractive optical element 57, the light use efficiency in the imaging lens 12 and the condenser lens 15 is increased. In addition, the shape of the pixels formed on the scanned surface 9 can be adjusted by the diffractive optical element 57, thereby improving the image quality.

  As described above, in the scanning image display device (projector) of the present invention, the device configuration is simple, so that the device can be reduced in size and weight to the extent that it can be portable. Can do. By configuring a portable projector, it is possible to easily view a large screen image. Generally, a display unit of a portable electronic device such as a mobile phone or a personal digital assistant (PDA) is small in order to ensure portability. If a portable projector is built in or externally attached to a portable electronic device, the display can be enlarged and viewed, and the display can be easily viewed.

  In the first to fifth embodiments, the light emitted from the laser light source is imaged by the imaging lens. However, when employing a light source device that emits substantially parallel light, an imaging optical system is used. It can be omitted.

It is a schematic diagram which shows schematic structure of the projector of 1st Embodiment. It is a figure which shows typically the path | route of the light in the projector of 1st Embodiment. It is a schematic diagram which shows schematic structure of the projector of 2nd Embodiment. It is a schematic diagram which shows schematic structure of the projector of 3rd Embodiment. (A)-(c) is a conceptual diagram which shows the drive method of a laser light source. It is a schematic diagram which shows schematic structure of the projector of 4th Embodiment. It is a schematic diagram which shows schematic structure of the projector of 5th Embodiment.

Explanation of symbols

1, 2, 3, 4, 5... Projector (scanning image display device), 11, 21r, 21g, 21b, 41r, 41g, 41b... Laser light source (light source device), 12. Lens (imaging optical system), 13 ... Diffusing plate (light diffusing element), 43 ... Diffracting optical element (light diffusing element), 14 ... Rotating mechanism (displacement mechanism), 44 ... Moving mechanism (Displacement mechanism), 15 ... condensing lens (condensing / parallelizing optical system), 16 ... scanning optical system, 27 ... dichroic prism (photosynthesis element), 47 ... triangular prism (photosynthesis element) ), 57... Diffractive optical element (photosynthesis element)

Claims (8)

A plurality of light source devices provided corresponding to each of a plurality of color lights having different wavelength ranges, and emitting corresponding color lights;
A light combining element that combines a plurality of color lights emitted from the plurality of light source devices;
The light synthesized by the light synthesizing element is incident to form a secondary light source image, and the light diffusing element that diffuses and emits the incident light; and
A displacement mechanism for displacing the light diffusing element;
A condensing and collimating optical system for condensing or collimating the light emitted from the light diffusing element;
Look including a scanning optical system for scanning the light emitted from the condensing-collimating optical system,
2. The scanning image display device according to claim 1, wherein the light synthesizing element is composed of diffractive optical elements having different diffusion coefficients in two directions that are not parallel to each other in a direction along a light incident surface . The scanning image display apparatus according to claim 1, further comprising an imaging optical system that forms an image of the light combined by the light combining element on the light diffusing element.   The scanning image display apparatus according to claim 2, wherein an F value of the condensing / collimating optical system is smaller than an F value of the imaging optical system.   The scanning image display device according to claim 1, wherein the light diffusing element is configured by a diffractive optical element.   5. The scanning image display element according to claim 4, wherein the light diffusing element has mutually different diffusion coefficients in two directions that are not parallel to each other in a direction along a light incident surface.   The said displacement mechanism rotates the said light-diffusion element within the surface which makes a normal direction the non-parallel direction with respect to the optical axis of the light which injects into the said light-diffusion element. The scanning image display device according to any one of the above.   The said displacement mechanism moves the said light-diffusion element in translation within the surface substantially orthogonal to the optical axis of the light which injects into the said light-diffusion element, It is any one of Claims 1-5 characterized by the above-mentioned. Scanning image display apparatus.   A plurality of light source devices provided corresponding to each of a plurality of color lights having different wavelength ranges, and emitting corresponding color lights;
  A light diffusing element that diffuses and emits the incident color light, as the secondary light source image is formed by the incident color light emitted from the plurality of light source devices;
  A displacement mechanism for displacing the light diffusing element;
  A condensing and collimating optical system for condensing or collimating the light emitted from the light diffusing element;
  A scanning optical system that scans the light emitted from the condensing and collimating optical system,
  The color image light emitted from the plurality of light source devices forms the secondary light source image at different positions in the light diffusing element.

Images