JP2007264076A - Picture projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the generation of horizontal lines or vertical lines generated when a picture is projected by scanning a one-dimensional optical modulation element. <P>SOLUTION: The picture projector has a modulation optical part provided with the one-dimensional optical modulation element, a projection optical part and a scanning optical part, wherein the scanning optical part is provided with a polygon mirror 20, at least one of the normal line directions v1 to v6 of mirror faces 201 to 206 of the polygon mirror 20 is tilted by a predetermined angle among θ1 to θ6 from the direction along a face 20u which is perpendicular to the rotation axis of the polygon mirror 21. Refection light is deflected and moves vertically, for example, the lateral streak due to the inhomogeneity of the optical modulation element is diffused and homogeneity is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image projection apparatus for projecting light modulated in accordance with image information by a one-dimensional light modulation element to display an image.

In image display devices such as projectors and printers, as a method for increasing the resolution of an image, a line-shaped light beam from a one-dimensional light modulation element is projected onto an image forming unit while being scanned by an optical scanning unit, and a two-dimensional image is formed. Methods of forming are known. As such a one-dimensional image display light modulation element, there is known a so-called diffraction light valve (GLV), which is an electrostatic drive type diffraction light modulation element developed by Silicon Light Machine, USA. (For example, refer to Patent Document 1).
This diffraction grating type light modulation element is a kind of MEMS (Micro Electro Mechanical Systems) using light diffraction, and it is possible to electrically control the gradation of light along with the action of optical switching. Yes. A large number of the light modulation elements are arranged to form a one-dimensional array structure, and a two-dimensional image is obtained by scanning light-modulated line-shaped light, that is, a one-dimensional image, with a scan mirror.
Therefore, when this GLV type light modulation element is used as compared with a normal two-dimensional display device, the number of pixels in the vertical direction of the screen is the same as the number of pixels in the one-dimensional array, but at least one pixel in the horizontal direction. Since the width is sufficient, the number of pixels (pixels) required for the two-dimensional image display is small. In addition, this optical diffraction modulation element can be configured to have a small size in a region that exhibits its optical modulation function, and can display a high resolution, a high switching speed, and a wide bandwidth. Further, since it is operated with a low applied voltage, it is expected to realize a very small display device.

The operation principle of this GLV type light modulation element will be briefly described with reference to FIGS. FIG. 13 is a schematic perspective configuration diagram of a main part of an example of a light modulation element having a GLV type, that is, a diffraction grating type configuration for displaying a one-dimensional image. As shown in FIG. 13, in this light modulation element 41, a common electrode 12 made of a polysilicon thin film or the like is formed on a substrate made of silicon or the like, and a strip ( Strip-shaped first electrodes 40a to 40d and second electrodes 41a to 41c are alternately formed. The first electrodes 40a to 40d are connected to the drive voltage power supply 43, and the second electrodes 41a to 41c are set to a fixed potential. Although not shown, at least the upper surfaces of the first electrodes 40a to 40d and the second electrodes 41a to 41c are formed with a reflective film made of aluminum or an aluminum alloy, and function as a reflective member.
During the operation of the light modulation element 31, the first electrodes 40a to 40d can move in a direction perpendicular to the reflection surface of the reflection film in accordance with the drive voltage, and the height of the reflection surfaces of the first electrodes 40a to 40d. (For example, the distance to the substrate) can be changed. The second electrodes 41a to 41c are fixed, for example, and the height of the reflecting surface is unchanged.
In addition, the number of the 1st electrode in the light modulation element corresponding to one pixel (pixel) and the 2nd electrode can be changed suitably.

  In this light modulation element, a normal type GLV in which the surface is arranged on a substantially flat surface when each electrode is not in operation, and each electrode is inclined at a predetermined angle from a reference plane (for example, the substrate surface of the light modulation element). A so-called blaze-type GLV has been proposed. 14 and 15 schematically show schematic cross-sectional configuration diagrams of examples of these types of light modulation elements. 14 and 15, the same reference numerals are given to the portions corresponding to those in FIG. In the example of FIGS. 14 and 15, as an example, the case where the number of first and second electrodes of the light diffraction modulation element corresponding to one pixel is three is shown.

  In the normal type, as shown in an example of operation in FIG. 13, when the movement amount Z1 of the first electrodes 40a to 40c is, for example, λ / 4 with respect to the wavelength λ of incident light, it is reflected in the direction opposite to the incident direction. 0th order diffracted light (not shown) and ± 1st order diffracted light Lr (+1) and Lr (−1) are reflected as diffracted light. For example, by using only + 1st order diffracted light, only one diffracted light can be imaged on a screen through a spatial filter and used for image display. Since no + 1st order diffracted light is generated during non-operation (when the drive voltage is zero), this off state corresponds to the dark state of the screen and the display screen is black. That is, by adjusting the drive voltage to the first electrodes 40a to 40c in accordance with the image information from the outside and controlling the movement amount Z1, it is possible to turn on / off the pixels and display the gradation between them. Become.

  On the other hand, in the blaze type, as shown in FIG. 15, the electrodes 40 a to 40 c and 41 a to 41 c are inclined with respect to the reference plane A (not shown, for example, a plane parallel to the substrate surface of the light diffraction modulation element) at an angle θ, for example. Deploy. At this time, the angle θ is preferably ¼λ with respect to the period of one electrode. During operation, the first electrodes 40a to 40c are moved so that the surfaces of the pair of first electrodes 40a to 40c and the second electrodes 41a to 41c form a single plane. At this time, if the movement amount Z2 is λ / 4 with respect to the wavelength λ of the incident light (that is, a step of ½λ every two electrode periods), only the + 1st order diffracted light is emitted. . Therefore, using this + 1st order diffracted light, only one diffracted light can be imaged on the screen through the spatial filter. That is, in the case of using a blazed light modulation element, the light use efficiency can be increased by adopting a configuration in which one of the reflected diffracted light is used.

US Patent Publication 2003 / 0035189A1 Specification

  In an image projection apparatus using a one-dimensional light modulation element such as the light modulation element having a GLV type structure as described above, the light modulation element can be simply configured, but the voltage response characteristics of each element are not uniform. In this case, that is, when the height of the above-described electrode varies and the diffraction angle becomes non-uniform, it is reflected as a horizontal stripe on the drawing surface by scanning. In order to solve such lateral stripes, for example, it is conceivable to improve the uniformity of the light modulation element. However, human visual sensitivity is sensitive to horizontal stripes (or vertical stripes if the scanning direction is up and down). For example, a horizontal stripe component of about 0.1% of the light intensity of the image signal is inserted into the image. Even just being detected, it is detected by the human eye. Further, when trying to display a complete black surface, even if the black contrast of each element is 10000: 1 or more, it can be visually recognized as a horizontal stripe, causing a sense of hindrance when recognizing an image. I will let you.

As the one-dimensional type light modulation element, in addition to the above GLV type light modulation element, for example, a liquid crystal element, a MEMS (Micro Mechanical Electric Systems) type light modulation element, or an LED (light emitting diode) or LD A light modulation element in which light emitting elements such as (laser diode) are arranged in an array can be applied.
However, a one-dimensional light modulation element that maintains uniformity of 0.1% or less for all pixels and realizes 10000: 1 as a black contrast over the entire light amount region as described above, The type is very difficult in the manufacturing process. In addition, it is conceivable to detect the non-uniformity of each pixel in advance and correct each pixel so as to correct the detected non-uniformity. Since the correction coefficient varies, it is difficult to reliably avoid the occurrence of the horizontal line (vertical line) as described above by such correction.

  In view of the above problems, an object of the present invention is to suppress the generation of horizontal lines or vertical lines that occur when an image is projected by scanning a one-dimensional light modulation element.

In order to solve the above-described problems, the present invention provides an image projection apparatus including a modulation optical unit including a one-dimensional light modulation element, a projection optical unit, and a scanning optical unit, and a polygon mirror is provided in the scanning optical unit. The at least one mirror surface of the polygon mirror is configured as a surface whose perpendicular direction is inclined with a predetermined inclination angle from a direction along a plane perpendicular to the rotation axis of the polygon mirror.
In the image projection apparatus of the present invention, an image signal deflection correction unit that corrects in advance deflection of a one-dimensional image due to a difference in tilt angle on each mirror surface of the polygon mirror may be provided.

As described above, according to the image projection apparatus of the present invention, the line-shaped light flux modulated by the one-dimensional light modulation element is scanned and projected by the polygon mirror, and the image is displayed on the screen or the like. In particular, the mirror surface of the polygon mirror is usually a plane perpendicular to the plane orthogonal to the rotation axis, that is, the perpendicular direction is a direction along the plane orthogonal to the rotation axis. On the other hand, in the present invention, the normal direction includes a mirror surface that is inclined from a direction along a plane orthogonal to the rotation axis.
When such a polygon mirror is used to scan light modulated in accordance with image information or the like by a one-dimensional light modulation element, for example, the image is deflected up and down by the tilt angle of the mirror surface. . Therefore, it is possible to suppress the horizontal line due to the nonuniformity of the light modulation element to the extent that it is diffused in the vertical direction and is hardly recognized by human eyes.
In addition, by providing an image signal correction unit that corrects in advance the deflection caused by the inclination of the polygon mirror, it is possible to suppress image blurring and to increase the inclination of the mirror surface, and to make the image non-uniformity more effective. It becomes possible to suppress the sex.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the horizontal line or vertical line which arises when scanning a one-dimensional type | mold light modulation element and projecting an image can be suppressed.

Examples of the best mode for carrying out the present invention will be described below, but the present invention is not limited to the following examples.
FIG. 1 is a schematic configuration diagram of an embodiment of an image projection apparatus having the configuration of the present invention. The image projection apparatus 50 of the present invention is used, for example, as a large screen projector, particularly as a digital image projector, or for computer image projection, and emits light after being modulated by a one-dimensional light modulation element. The modulation optical unit 10, the projection optical unit 97 such as a projection lens that forms an image on the screen 30, and the light emitted from the modulation optical unit 10 in a direction orthogonal to the longitudinal direction of the one-dimensional light modulation element The scanning optical unit for displaying an image on the screen 30, in this case, the polygon mirror 20 is provided.

  In this example, laser light sources 82R, 82G, and 82B that emit coherent light such as semiconductor lasers to the modulation optical unit 10, and mirrors 84R and 84G that are sequentially provided on the optical path for each laser light source, respectively. , 84B, each color illumination optical system (lens group) 86R, 86G, 86B, and one-dimensional light modulation elements 88R, 88G, 88B functioning as light modulation elements. Each color illumination optical system (lens group) 86R, 86G, 86B has a function of adjusting the shape of the light flux so that the light from the light source is efficiently irradiated to the one-dimensional light modulation elements 88R, 88G, 88B. Further, a color synthesis filter 90 such as a dichroic mirror that synthesizes a plurality of color lights is disposed on the optical path of each light whose light intensity is modulated by the light modulation elements 88R, 88G, and 88B, and the light path on the emission side thereof. , A spatial filter 92, a diffuser 94, and a mirror 96. The modulated light emitted from the modulation optical unit 10 is scanned by the polygon scanner 20 via the projection optical unit 97 and imaged on the screen 30. The screen 30 can be configured as, for example, a substantially cylindrical surface having a rotation center axis of the polygon scanner 20 as a substantially central position.

In the case of performing color image display, the modulation optical unit 10 may include a laser light source that emits light beams of three primary colors, such as red, green, and blue, respectively. That is, as the laser light sources 82R, 82G, and 82B, red light (for example, wavelength 642 nm, light output about 3 W), green light (for example, wavelength 532 nm, light output about 2 W), blue light (wavelength 457 nm, light output about 1. A laser diode or the like that emits a 5 W laser can be used. Note that the wavelength and optical output of the laser light are not limited to these.
As the light modulation elements 88R, 88G, 88B, for example, GLV type, that is, diffraction grating type light modulation elements, which are MEMS devices by the electrostatic drive method described above, can be used, and other semiconductor laser diodes or semiconductor light emitting devices can be used. A light modulation element in which diodes are arranged in an array, a light modulation element in which liquid crystal image elements are arranged one-dimensionally, or the like can be used.

In the modulation optical unit 10 having such a configuration, the red, green, and blue laser beams emitted from the laser light sources 82R, 82G, and 82B pass through the mirrors 84R, 84G, and 84B, respectively, and the respective color illumination optical systems 86R, 86G, 86B is synchronously input to each of the light modulation elements 88R, 88G, 88B.
Further, each laser beam is diffracted by, for example, GLV type light modulation elements 88R, 88G, and 88B to be modulated corresponding to image information and the like, and these three colors of modulated light are synthesized by the color synthesis filter 90, Subsequently, only the signal component is extracted by the spatial filter 92.
Next, the RGB image signal is reduced in laser speckle by the diffuser 94, passed through a mirror 96 and a lens 97, and is scanned by a polygon scanner 20 having four mirror surfaces, for example, which is a scanning illumination system synchronized with the image signal. The image is developed and projected as a full-color image on the screen 30.

  Thus, in the case of a so-called post-projection configuration in which the scanner 20 is arranged after the lens 97, the area through which light is transmitted uses only the so-called core portion of the lens 97, so that the projection is performed on the cylindrical screen 30. The image is less deteriorated at the four corners of the image, and therefore it is possible to display an image with clear image quality up to the four corners of the screen 30.

  And the polygon mirror 20 used in the image projection apparatus 50 of the present invention has its mirror surface, as shown in the schematic perspective view of the example in FIG. 2, the first to sixth surfaces 201 to 206 in the illustrated example, The perpendicular direction indicated by the arrows v1 to v6 is inclined at a predetermined inclination angle θ1 to θ6 from a plane perpendicular to the rotation axis of the polygon mirror 21, in the illustrated example, along the plane of the upper surface 20u, that is, a direction indicated by a broken line. It is configured as a surface that becomes the direction. In the illustrated example, each of the inclination angles θ1 to θ6 is shown as an angle from a normal direction in a plane perpendicular to the upper surface 20u. As described above, when the mirror surface is formed by inclining in the direction perpendicular to the upper surface 20 u, the reflected image light is deflected and projected above and below the screen 30. Note that the polygon mirror used in the present invention is not limited to the shape having the six mirror surfaces shown in FIG. 2, and it is possible to use three or more polygon mirrors.

On the other hand, FIG. 3 shows a schematic perspective configuration diagram of a normal polygon mirror. When the general polygon mirror 21 has, for example, six mirror surfaces, the first surface 211 to the sixth surface 216 have all the perpendicular directions indicated by arrows v11, v12,. The surface is perpendicular to the surface, for example, the direction along the surface of the upper surface 21u. In this case, the scanning trajectory of the one-dimensional image also passes through the same trajectory on all mirror surfaces.
FIG. 4 shows an example of a scanning optical unit that scans light from a one-dimensional light modulator using such a general polygon mirror. In FIG. 4, the light emitted from the light source 151 is efficiently illuminated by the lens 152 onto the one-dimensional light modulation element 153 as indicated by the arrow Li1, and is modulated by the light modulation element 153 according to image information or the like. The reflected light is reflected by the mirror surface of the polygon mirror 120 via the projection lens 154 as indicated by the arrow L1m, projected onto the screen 130 as indicated by the arrow Ls1, and imaged on the screen 130. The rotation axis of the polygon mirror 120 is indicated by c1, the rotation direction is indicated by an arrow r1, and the scanning direction of the image light on the screen 130 is indicated by an arrow s1. At this time, if a non-uniform pixel exists due to a defect or the like in a part of the light modulation element 153, as indicated by a solid line L, a horizontal stripe Ld along the scanning direction s1 is generated on the screen 130. FIG. 5 schematically shows an example of a display image on the screen 130 in a state in which such horizontal stripes Ld1, Ld2,. As described above, since the scanning trajectory of the one-dimensional image passes through the same trajectory on all surfaces of the polygon mirror, such lateral stripes that do not exist in the original image are generated.

  As the non-uniformity of the image display element, even if it is non-uniformity that generates an error of about 0.1% with respect to the target light intensity, it can be identified in terms of human visual characteristics. . Further, in the dark part of the image (when it is off), the horizontal stripes can be perceived only by generating leakage light with a contrast of each pixel of about 1 / 10,000. As described above, it is extremely difficult to eliminate such minute errors and non-uniformities in the manufacturing process, which may lead to a decrease in yield and productivity, and consequently high costs.

  On the other hand, in the image projection apparatus of the present invention, as described in FIG. 2 above, at least one surface of the polygon mirror, in the example of FIG. 2, a surface in which the normal direction of all surfaces is orthogonal to the rotation axis. In this case, the light reflected by each mirror surface is deflected in the vertical direction of the screen for each mirror surface and imaged on the screen or the like. The one-dimensional image displayed in this manner is scanned with the display position moved up and down. As a result, the non-uniformity of the one-dimensional light modulation element, that is, the non-uniformity of the modulation degree due to the variation in diffraction angle generated in the manufacturing process can be diffused in the vertical direction. This makes it difficult to see the horizontal stripes in the eyes, and improves the uniformity of the image.

FIG. 6 shows a schematic perspective configuration diagram of an example of the scanning optical unit of the image projection apparatus according to the embodiment of the present invention using such a polygon mirror. In this example, an image signal deflection correction unit for correcting in advance the deflection of the one-dimensional image due to the difference in tilt angle on each mirror surface of the polygon mirror is provided, and further, the distortion on the screen of the light scanned by the polygon mirror is provided. An example in which an image signal distortion correction unit for correcting the above is provided will be described.
That is, in this case, as shown in FIG. 6, an image signal clipping unit 61, an image signal deflection correction unit 62, and an image signal distortion for clipping an image signal into a line shape for output from the image signal Sg to a one-dimensional light modulation element. A correction unit 63 is provided, and the corrected image signal Sm is output from the image signal distortion correction unit 63 to the one-dimensional light modulation element 88. Light Li from a light source (not shown) is modulated based on the image signal corrected by the light modulation element 88 and emitted as indicated by an arrow Lm, reflected by the polygon mirror 20 described above, and as line-shaped image light Ls. For example, the image is projected onto a flat screen 31 and scanned on the screen 31 as indicated by an arrow S to display an image. In this case, the polygon mirror 20 is rotated about the rotation axis c as indicated by the arrow r, the rotation angle is detected by the rotation angle detection unit 64, and the rotation angle signal Sa is converted into the image signal deflection correction unit 62 and the image. It is configured to be output to the signal image signal distortion correction unit 63.

  As described above, in the image projection apparatus of the present invention, the reflected image light is deflected by inclining the mirror surface of the polygon mirror. For example, when deflecting in the vertical direction, the polygon mirror surface is rotated. The trajectory of the formed one-dimensional image moves up and down for each mirror surface. Therefore, the original image shown in FIG. 7A is a superposition of images that have moved up and down as shown in FIG. 7B, for example.

  In order to prevent such overlapping of images, the image signal deflection correction unit 5 corrects, for example, vertical movement due to image deflection for each mirror surface, for example. That is, when the mirror surface tilt direction is upward, the image position is corrected downward, and when the mirror surface tilt direction is downward, the image position is corrected upward. As a result, the image on the screen 31 can be displayed at a fixed position as shown in FIG. 7C without causing the one-dimensional image due to the tilt of the mirror surface of the polygon mirror to move up and down. Become. On the other hand, the effect of non-uniformity due to the one-dimensional light modulation element is that the image fluctuates up and down for each mirror surface. Is done.

Specifically, the tilt angle of the mirror surface is substantially selected depending on the distance between the polygon mirror and the screen. As a result of the study by the present inventor, for example, vertical deflection of 10 to 20 pixels (pixels) can cause a significant effect on human eyes, and non-uniformity is eliminated to the extent that horizontal lines are hardly visible. It was confirmed that Although it depends on the distance between the polygon mirror and the screen, for example, if the perpendicular direction of the mirror surface is inclined by 1 ° from the direction along the rotation axis, the light is deflected by 2 °, and the horizontal lines can be sufficiently reduced on the screen. It becomes possible.
Thus, by tilting the mirror surface, for example, upward or downward, an invalid area where an image cannot be displayed is generated at the upper and lower portions of the screen, and this portion needs to be at a dark level. Therefore, if the inclination angle is increased too much, this invalid region becomes wide. Therefore, it is practically preferable to suppress the inclination angle to about 10 ° or less, and more desirably to about 5 ° or less.

In this example, a flat screen is used as the screen 31. However, as described above, the image signal distortion correction unit 64 is provided on the screen 31 of the image light scanned by the polygon mirror 20. Can be corrected.
Explaining this, when the line-shaped image light modulated by the one-dimensional light modulation element 88 is scanned, it is projected onto a cylindrical screen 30, that is, a cylindrical screen 30 having the rotation axis of the polygon mirror 20 as a substantially central axis. In this case, the light scanned schematically in FIG. 8 is projected without distortion from the left end to the right end of the screen 30 as indicated by an arrow, so that the image is not distorted.
On the other hand, as shown in FIG. 9, when the screen 31 is planar, when the incident light has an incident angle with respect to the mirror surface, it is not scanned directly as indicated by the dashed arrow, but is indicated by the solid arrow. A curved trajectory will be drawn. That is, the image is enlarged at the left end and the right end as compared with the central portion. In the present invention, since the mirror surface of the polygon mirror is tilted, it is particularly important to correct such distortion when projecting onto a flat screen.

In order to eliminate such image distortion, in the image signal distortion correction unit 64, for example, the planar image shown in FIG. 10A is enlarged at the center of the screen as shown in FIG. 10B, and is reduced vertically at the left and right edges. The corrected image is corrected in advance. With this correction, even when an image is projected onto the flat screen 31, the same image as the original image can be displayed without distortion.
The correction of the image signal is performed by adjusting the signal output timing in accordance with the rotation start and end of scanning of each mirror surface based on the rotation angle signal Sa obtained from the rotation angle detection unit 64 of the polygon mirror 20. Thus, it is possible to reliably correct the signal for each mirror surface.

As described above, according to the image projection apparatus of the present invention, it is possible to suppress or avoid the generation of horizontal lines or vertical lines that appear on the image display surface due to the non-uniformity of the light modulation elements, and to prevent image recognition. It is possible to improve the uniformity of the image by improving the feeling of interference.
Therefore, according to the present invention, it is possible to simplify the manufacturing process by simplifying the inspection process in the manufacturing process, for example, which is performed in order to improve the uniformity of the light modulation element itself.
As described above, according to the present invention, it is possible to achieve image uniformity with a simple configuration that only changes the shape of the polygon mirror, and thus, the manufacturing cost of the entire image projection apparatus can be reduced.

In the above-described example, an example in which a GLV type light modulation element is used as the one-dimensional type light modulation element has been described. However, in the image projection apparatus of the present invention, the one-dimensional type light modulation element is replaced with such a one-dimensional type light modulation element. For example, a light-emitting element with a light modulation function based on drive output modulation of light-emitting elements arranged in a row such as an array LED or an array laser, or a minute two-dimensional light modulation such as a liquid crystal element or a DMD element. The present invention is also applicable when using light modulation elements in which elements are arranged in an array.
Further, the present invention can also be applied to a configuration in which a one-dimensional image is modulated by a plurality of light modulation elements arranged in a line instead of a single light modulation element that modulates a one-dimensional image. is there.

Next, in the image projection apparatus of the present invention, a case will be described in which the inclination angle of the mirror surface of the polygon mirror is changed as an angle corresponding to a half interval of one pixel interval of the light modulation element.
In this case, the angle of inclination of the mirror surface of the polygon mirror is configured so that, for example, adjacent mirror surfaces are inclined corresponding to an interval approximately half of the interval between the pixels arranged in a line by the light modulation element. . This inclination angle is selected according to the distance between the pixels of the light modulation element and the distance from the light modulation element to the screen via the projection lens. For example, every other mirror surface is configured as a surface slightly inclined upward and downward.
In the case of such a configuration, as shown in FIG. 11, the image light LA reflected from the upward mirror surface on the screen 30 and the image light LB reflected from the downward mirror surface are Are displayed shifted by half a pixel. As a result, interlaced display is possible, and the resolution can be improved almost twice.

  FIG. 12 schematically shows the pixels displayed by the mirror surfaces in this case. Each pixel A1, A2, A3,... Of the image light from the upward mirror surface shown in FIG. 11 is represented by A1 ′, A2 ′, A3 ′,. Corresponding changes are displayed. The image lights B1, B2, B3,... From the adjacent downward mirror surfaces are displayed while being shifted downward by half a pixel, which is approximately half of the interval between the pixels, in this case, the interval between the pixels A1 and A2. .

In the above-described diffraction grating type light modulation element such as the GLV type, it is possible to configure the pixels without gaps. However, when an image is displayed using such a polygon mirror, the luminance between the pixels is low. It is possible to interpolate the region, or it is possible to configure the pixels so as to be separated from each other. In addition, when a light emitting element with a light modulation function such as an array liquid crystal element, an array LD, or an array LED arranged in a one-dimensional type having another configuration is used instead of the light modulation element, the pixels are separated. There is a dark level area in between. Even when such a light modulation element is used, such a gap can be interpolated by displaying the interlaced display with the polygon mirror having the above-described configuration, and an image can be displayed with better image quality. It becomes possible. As the interval between pixels increases, the effect of improving the image quality by such interpolation can be obtained.
In the above example, the angle of inclination of the polygon mirror is set to two directions, but it is selected to be three or more directions and shifted in the pixel arrangement direction, for example, 1/3, 1/4,. It is also possible to display an image with deflection. That is, an arbitrary number of pixels of 2 or more can be slightly shifted between one pixel of line-shaped image light projected by one mirror surface, that is, the inclination angle of the polygon mirror can be set to n. An image can be displayed by selecting (n is a natural number of 2 or more) directions and deflecting the pixels by shifting them by 1 / n. In this case, it is possible to arbitrarily select the number of pixels to interpolate between the pixels in accordance with the pixel interval of the light modulation element. This makes it possible to maintain good image quality with a simple configuration in which the angle of the mirror surface of the polygon mirror is selected without being limited to the characteristics of the light modulation element, and the degree of freedom in designing the light modulation element. It is possible to increase.

  In addition, this invention is not limited to the structure demonstrated in each above-mentioned each embodiment, For example, when using a monochromatic light source as a light source, when using a two-color light source, and 3 other than red, green, and blue The present invention can also be applied to a case where a color light source is used or a case where four color light sources are used. Further, as described above, various one-dimensional type light modulation elements can be applied as the light modulation element, and various modifications and changes can be made without departing from the structure of the present invention. Nor.

It is a schematic block diagram of an example of the image projection apparatus which concerns on the embodiment of this invention. It is a schematic perspective view of an example of a polygon mirror used in the image projection apparatus according to the embodiment of the present invention. It is a schematic perspective view of an example of a conventional polygon mirror. It is a schematic perspective block diagram of an example of the scanning optical part of the image projection apparatus using a polygon mirror. It is explanatory drawing of the display image which nonuniformity generate | occur | produced. 1 is a schematic perspective configuration diagram of a main part of an example of an image projection apparatus according to an embodiment of the present invention. A is a schematic plan view of an original image. B is a schematic plan view of an image moved by deflection of a polygon mirror. C is a schematic plan view of an image corrected by the image signal deflection correction unit. It is a typical top view which shows the locus | trajectory of the image projected on the cylindrical screen. It is a typical top view which shows the locus | trajectory of the image projected on the planar screen. A is a plan view schematically showing image information corrected by the image signal distortion correction unit. B is a plan view schematically showing an image obtained by projecting the corrected image signal onto a flat screen. It is explanatory drawing of the display mode of the pixel of the image projection apparatus which concerns on the example of embodiment of this invention. It is explanatory drawing of the display mode of the pixel of the image projection apparatus which concerns on the example of embodiment of this invention. It is a schematic perspective view of an example of a one-dimensional type light modulation element. It is explanatory drawing of the diffraction aspect of an example of a one-dimensional type | mold light modulation element. It is explanatory drawing of the diffraction aspect of an example of a one-dimensional type | mold light modulation element.

Explanation of symbols

  10. Modulation optical unit, 20. Polygon mirror, 20u. Top surface, 21. Polygon mirror, 30. Screen, 31. Screen, 50. Image projection device, 82R. Light source, 82G. Light source, 82B. Light source, 86R. Illumination optical system, 86G. Illumination optical system, 86B. Illumination optical system, 88R. Light modulation element, 88G. Light modulation element, 88B. Light modulation element, 90. Color synthesis filter, 92. Spatial filter, 94. Diffuser, 96. Mirror, 97. Projection optical unit, 201. First surface, 202. Second surface, 203. Third surface, 204. Fourth surface, 205. Fifth surface, 206. Sixth aspect

Claims (5)

In an image projection apparatus having a modulation optical unit including a one-dimensional light modulation element, a projection optical unit, and a scanning optical unit,
The scanning optical unit is provided with a polygon mirror,
The at least one mirror surface of the polygon mirror is a surface whose perpendicular direction is a direction inclined at a predetermined inclination angle from a direction along a plane perpendicular to the rotation axis of the polygon mirror. Forming equipment. The image projection apparatus according to claim 1, further comprising an image signal deflection correction unit configured to previously correct deflection of the one-dimensional image due to the difference in the tilt angle on each mirror surface of the polygon mirror. The image projection apparatus according to claim 1, further comprising an image signal distortion correction unit that corrects distortion on a screen of light scanned by the polygon mirror. The image projection apparatus according to claim 1, wherein the light projected from the scanning optical unit forms an image on a substantially cylindrical screen. The image projection apparatus according to claim 1, wherein an inclination angle of a mirror surface of the polygon mirror is changed as an angle corresponding to a half interval of one pixel interval of the light modulation element.

Images