JP4868966B2 - Image display device - Google Patents

Description

  The present invention relates to an optical scanning type image display device that displays an image by scanning a screen with laser light whose intensity is modulated in accordance with input image data.

  As one of projection type image display apparatuses, there is an optical scanning type image display apparatus that displays an image by scanning a laser beam intensity-modulated according to input image data on a screen (see, for example, Patent Document 1). ). Patent Document 1 discloses an image display device that simultaneously displays a plurality of pixels by independently modulating a plurality of laser beams. Since this image display apparatus draws directly on the screen using laser light having high directivity, a clear image can be displayed. Further, since the laser beam has an ideal single wavelength spectrum distribution, the optical scanning type image display device is excellent in color reproducibility. Furthermore, by simultaneously drawing different areas in the screen in parallel with a plurality of laser beams, the scanning speed and modulation speed of the laser beams can be reduced.

JP-A-9-134135

  However, in an image display device that draws different areas in the screen simultaneously in parallel with a plurality of laser beams, screen irregularities and glare called speckle noise may occur due to the interference of the plurality of laser beams. There is a problem that the phenomenon may deteriorate the quality of the displayed image.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and the purpose of the present invention is to improve the quality of a displayed image even when different areas in a screen are simultaneously scanned by a plurality of laser beams. An object of the present invention is to provide an image display device that can be maintained.

An image display apparatus according to the present invention has a light source unit having a plurality of light emitting elements that output a plurality of laser beams of the same color, and moves the irradiation positions of the plurality of laser beams from the plurality of light emitting elements of the light source unit in the main scanning direction An optical scanning unit that performs main scanning and a sub-scan that moves an irradiation position in the main scanning in a sub-scanning direction, a screen that displays an image by receiving laser light that is main-scanned and sub-scanned by the optical scanning unit, and A display control unit that individually modulates the intensity of a plurality of laser beams from a plurality of light emitting elements of the light source unit according to input image data, and controls main scanning and sub-scanning by the optical scanning unit ; A plurality of laser beams of the same color output from the plurality of light emitting elements of the light source unit, and the display control unit is displayed on the screen within a period of one frame. each Element has been characterized by controlling so as to draw over a plurality of laser beams from a plurality of light emitting elements of the same color output of the plurality of light emitting elements of the light source unit.

  According to the present invention, there is an effect that it is possible to reduce unevenness and glare of the screen called speckle noise, which are generated by interference of laser light, and to realize stable and high-quality image display.

  FIG. 1 is a diagram schematically showing an overall configuration of an optical scanning type image display apparatus of the present invention. The optical scanning type image display apparatus of the present invention is, for example, a large-screen projection type image display apparatus for home or business use using laser light.

  The image display apparatus shown in FIG. 1 includes a light source unit 1 having a plurality of light emitting elements (that is, light emitting units) manufactured so as to output a plurality of laser beams of the same color. As shown in FIG. 1, the light source unit 1 includes a red laser light source 1 r provided with a plurality of light emitting elements arranged in an array that outputs a plurality of red (R) laser beams Lr, and a green (G The laser light source 1g for green provided with a plurality of light emitting elements arranged in an array that outputs a plurality of laser beams Lg) and an array that outputs a plurality of blue (B) laser beams Lb And a blue laser light source 1b including a plurality of light emitting elements. 1 shows a case where a plurality of light emitting elements of the laser light sources 1r, 1g, and 1b for each color are arranged in parallel to the paper surface on which FIG. 1 is drawn. The direction may be a direction perpendicular to the paper on which FIG. 1 is drawn or an oblique direction. Further, FIG. 1 shows a case where the light source unit 1 is composed of RGB three-color laser light sources 1r, 1g, and 1b, but the number of laser light sources may be 2 or less or 4 or more.

  Further, the image display device shown in FIG. 1 combines a red laser light Lr from the laser light source 1r, a green laser light Lg from the laser light source 1g, and a blue laser light Lb from the laser light source 1b. 2 has. The light combining unit 2 has a red dichroic mirror 2r configured to obtain a high reflectance only at a part of wavelengths corresponding to the emission color of the laser light source 1r, and one corresponding to the emission color of the laser light source 1g. The green dichroic mirror 2g configured to obtain a high reflectance only with respect to the wavelength of the portion, and a high reflectance only with respect to a part of the wavelengths corresponding to the emission color of the laser light source 1b. The blue dichroic mirror 2b is configured, and the three color laser beams Lr, Lg, and Lb from the respective light emitting elements of the laser light sources 1r, 1g, and 1b of the respective colors are superimposed. In addition, the structure of the photosynthesis part 2 is not limited to what was shown by FIG. Further, it is possible to make the laser beams from the laser light sources 1r, 1g, and 1b of the respective colors enter the optical scanning unit 4 without providing the light combining unit 2.

  Further, the image display apparatus shown in FIG. 1 has an irradiation lens 3 for condensing laser light, a main scanning for moving the irradiation positions of a plurality of laser lights in the main scanning direction Dm, and an irradiation position by the main scanning in the sub scanning direction. An optical scanning unit 4 that performs sub-scanning to move to Ds, a projection lens 5, a screen 6 that displays an image by receiving laser light that is main-scanned and sub-scanned by the optical scanning unit 4, and the intensity of a plurality of laser beams And an image display controller (display control unit) 7 for controlling main scanning and sub-scanning by the optical scanning unit.

  FIG. 2 is a diagram showing an arrangement of a plurality of laser beams (when combining laser beams of respective colors) in the image display apparatus shown in FIG. In FIG. 2, circles with symbols Lr, Lg, and Lb indicate a plurality of laser beams arranged in the sub-scanning direction Ds. The arrangement direction of the plurality of laser beams is not limited to the sub-scanning direction Ds (in the case of the first embodiment described later), but is oblique to the sub-scanning direction Ds or the main scanning direction Dm (second embodiment described later). Or the main scanning direction Dm (in the case of Embodiment 3 described later).

  FIG. 3 is a diagram illustrating an arrangement of a plurality of laser beams (when laser beams of respective colors are not combined) in the image display apparatus illustrated in FIG. In FIG. 3, circles with a symbol Lr indicate a plurality of red laser beams arranged in the sub-scanning direction Ds, and circles with a symbol Lg indicate a plurality of green lasers arranged in the sub-scanning direction Ds. The circles marked with the symbol Lb indicate a plurality of blue laser beams arranged in the sub-scanning direction Ds. The arrangement direction of the plurality of laser beams is not limited to the sub-scanning direction Ds (in the case of the first embodiment described later), but is oblique to the sub-scanning direction Ds or the main scanning direction Dm (second embodiment described later). Or the main scanning direction Dm (in the case of Embodiment 3 described later).

Embodiment 1 FIG.
FIG. 4 is a diagram schematically showing the configuration of the image display apparatus according to Embodiment 1 of the present invention (laser light source shows only for red). FIG. 5 is a perspective view schematically showing the configuration of the laser light source 1r of the image display apparatus according to the first embodiment.

  In the image display device according to Embodiment 1, the plurality of light emitting elements 101 of the laser light source 1r are arranged so as to simultaneously draw a plurality of pixels arranged in the sub-scanning direction Ds on the screen 6. Although FIG. 4 shows the laser light source 1r, the laser light source 1g and the laser light source 1b may be arranged in parallel with the laser light source 1r. In addition, by providing a light combining unit (a configuration corresponding to reference numeral 2 in FIG. 1), laser beams of RGB three primary colors may be superimposed and irradiated. As the laser light source 1r, for example, one in which 80 light emitting elements 101 are arranged in an array at an equal pitch on the same substrate can be used. However, the number of the light emitting elements 101 is not limited to 80, and may be a plurality other than 80. Note that the RGB three-color laser light sources 1r, 1g, and 1b (only 1r is shown in FIG. 4) have the same arrangement structure of light emitting elements.

The optical scanning unit 4 has a minute rotating mirror. In FIG. 4, ROT indicates the rotation direction of the rotating mirror of the optical scanning unit 4 during main scanning, AX _ROT indicates the rotation axis of the rotating mirror of the optical scanning unit 4 during main scanning, and TILT indicates sub-scanning. AX _TILT indicates the tilt axis (rotation axis) of the rotating mirror of the optical scanning unit 4 during sub-scanning. As shown in FIG. 4, the minute rotating mirror of the optical scanning unit 4 rotates independently in two axes AX _ROT and AX _TILT . In order to reduce the size of the minute rotating mirror, the reflecting surface of the rotating mirror is configured in the vicinity of the condensing point of the laser beam by the irradiation lens 3. The laser beam scanned by the optical scanning unit 4 is projected on the screen 6 through the projection lens 5. The image display controller 7 (FIG. 1) modulates the light emission intensity for each light emitting element of the laser light sources 1r, 1g, and 1b according to input image data (not shown), and synchronizes with the horizontal and vertical synchronization signals of the image. Then, the optical scanning unit 4 is controlled so that the laser light is scanned in the main scanning direction Dm and the sub-scanning direction Ds. An image is directly drawn on the screen 6 by scanning in the main scanning direction Dm and the sub-scanning direction Ds by the optical scanning unit 4 while intensity-modulating the laser beams output from the laser light sources 1r, 1g, and 1b.

  FIG. 6 is an explanatory diagram illustrating a laser beam scanning method of the image display apparatus according to the first embodiment.

  The plurality of light emitting elements 101 provided in each of the laser light sources 1r, 1g, and 1b are geometrically arranged so as to be arranged at an equal pitch in the sub-scanning direction Ds. For this reason, at the time of main scanning, a drawing spot 102 from a plurality of light emitting elements 101 is a pixel row having the same number of lines as the number of adjacent light emitting elements arranged in the sub-scanning direction Ds (in FIG. 6, solid line arrows extending in the horizontal direction). ) At the same time. That is, when a laser light source having 80 light emitting elements is used, 80 pixel lines (scanning lines) are simultaneously drawn in one main scanning.

  In the sub-scanning, for each main scan, adjustment is performed so as to move, for example, two lines in the pixel row in the sub-scanning direction Ds with respect to the previous main scan. While an 80-line pixel row is drawn in one main scan, the movement amount by the sub-scan is 2 lines for each main scan, so that 78 lines are drawn overlappingly. When the entire screen is sequentially drawn by such a scanning method, each pixel column is drawn with a laser beam emitted from a different light emitting element 101 for a total of 40 times. However, the distance moved by one sub-scan may be the number of lines other than two lines as long as the number of lines is less than the number of light emitting elements.

  When the scanning method according to the first embodiment is used, redundant main scanning lines (excess main scanning that is not used as a display screen) are provided outside the screen so that each pixel row in the main scanning direction in the effective screen has the same number of times of drawing. Line) must be prepared.

  Further, when the scanning method of the first embodiment is used, a plurality of pixel rows are drawn at a time in one main scan, and in the sub-scan, each main scan moves by two pixel rows. The number of times may be approximately half of the total number of pixel columns of the drawn image. Accordingly, the moving speed of the light scanning unit 4 and the light emission intensity modulation speed of each light emitting element 101 become lower than in the case of scanning with a light source of a single light emitting element, and an image display apparatus can be manufactured easily and at low cost. Is possible.

  Furthermore, since the same image is drawn several times with light from different light emitting elements 101, the light emission intensity of each light emitting element 101 is made lower than that when a light source of a single light emitting element is used. And the reliability of the light source is improved.

  By the way, in an image display device using a laser light source, interference of highly coherent laser light causes complicated brightness distribution and angular distribution of scattering intensity on the screen, resulting in unevenness and glare on the screen. The display quality may be reduced. However, the laser beam exhibits high coherence in the case of interference due to the laser beam emitted from a single light emitting element. A complex interference pattern called speckle is a phenomenon in which light emitted from the same light-emitting element is disturbed in the wavefront of the light wave due to various factors such as refraction by the optical element placed in the propagation path, and the phase of the overlapping light This is caused by strengthening or canceling each other in a specific direction or position where the two are aligned. Even if the light emitting elements are manufactured in the same configuration, the propagation paths of the laser beams emitted from different light emitting elements are different, so that the wavefront of the light wave and the fluctuation thereof are also different, and the screen 6 is affected by interference. The brightness distribution and the angular distribution of the scattering intensity generated in the pattern are different for each light emitting element.

  When the same pixel is drawn repeatedly with laser light from different light emitting elements, the laser light emitting element is different for each drawing, so the unevenness and glare that occurs on the drawing pixels differ from pattern to pattern for each drawing. Become. Further, the unevenness and the glare pattern for each drawing are not only light emitting elements but also light emitted at different timings, so that they do not interfere with each other.

  In the optical scanning method according to Embodiment 1, the same pixel is drawn by laser light emitted from different light emitting elements 101 over 40 times. At that time, unevenness and glare due to interference of laser light occur in different patterns for each drawing repeated with light from different light emitting elements 101. The visually recognized image is an average of unevenness and glare of patterns that differ for each drawing. That is, in the optical scanning method according to the first embodiment, unevenness and glare of different patterns are averaged by overlapping 40 times, and the unevenness and glare of the screen due to interference are eliminated as a whole, and the drawing is smooth and has high display quality. An image can be displayed.

In addition, a plurality of laser beams of the same color output from a plurality of light emitting elements of a laser light source have a difference in wavelength due to characteristic variation of the plurality of light emitting elements. In addition, a plurality of laser beams of the same color output from a plurality of light emitting elements of a laser light source have a difference in polarization state due to characteristic variation of the plurality of light emitting elements. Such a difference in wavelength and polarization state hardly causes an interference pattern. In addition, in order to obtain a different wavelength and polarization state for each light emitting element 101, a configuration including a resonator mirror having slightly different reflection characteristics for each light emitting element and / or a configuration including a phase difference plate for changing the polarization state. It may be adopted.

Embodiment 2. FIG.
FIG. 7 is a diagram schematically showing the configuration of the image display apparatus according to Embodiment 2 of the present invention (laser light source shows only for red). FIG. 8 is a diagram schematically showing a configuration of a laser light source of the image display apparatus according to the second embodiment.

  In each of the plurality of light emitting elements 101 arranged in the sub scanning direction Ds, it is desirable that the beam diameter of the laser light and the arrangement pitch of the light emitting elements 101 in the sub scanning direction coincide with each other. However, in the first embodiment, when a plurality of semiconductor lasers are integrated and manufactured on the same substrate and used as a light source having a plurality of light emitting elements 101, the heat generation density decreases as the distance between the light emitting elements increases. The pitch between the light emitting elements 101 is set wider than the beam diameter of the laser light because the light source can be easily cooled. Therefore, in the second embodiment, the entire light source unit 1 is inclined with respect to the main scanning direction Dm (or with respect to the sub-scanning direction Ds). By such a measure, the arrangement pitch P of the light emitting elements 101 in the sub scanning direction can be arranged so as to coincide with the beam diameter B of the laser light.

  In the second embodiment, points other than those described above are the same as those in the first embodiment.

Embodiment 3 FIG.
FIG. 9 is a diagram schematically showing the configuration of the image display apparatus according to Embodiment 3 of the present invention (laser light source shows only for red). FIG. 10 is a diagram schematically showing a configuration of a laser light source of the image display apparatus according to the third embodiment.

  In the first embodiment, the light emitting elements 101 arranged on the same substrate are arranged at equal intervals in the sub-scanning direction Ds, and the pixel rows arranged in the sub-scanning direction simultaneously by the number of the light-emitting elements 101 in one main scanning. Was configured to draw. On the other hand, in the third embodiment, as shown in FIG. 10, the light emitting elements 101 are arranged in a direction parallel to the main scanning direction.

  FIG. 11 is an explanatory diagram illustrating a laser beam scanning method of the image display apparatus according to the third embodiment.

  As shown in FIG. 11, according to the image display device according to the third embodiment, the same pixel is sequentially drawn with light from different light emitting elements with one main scan. Also in this case, since the same pixel is drawn with light 102 from different light emitting elements 101, image unevenness and glare due to laser light interference can be reduced for the reason described in the first embodiment.

  In the case of the scanning method of the first embodiment, if even one of the plurality of light emitting elements 101 has a defect, the scanning line drawn by the defective light emitting element becomes darker than the other scanning lines and appears on the screen. Line-shaped unevenness may occur, but in the case of the scanning method of Embodiment 3, even if some of the plurality of light emitting elements 101 are defective, the drawn image is slightly over the entire screen. Only a decrease in brightness occurs, and no line-like unevenness occurs on the screen. Therefore, the reliability of the light source can be improved and the cost can be reduced.

  In the scanning method according to the first embodiment, since a plurality of pixel columns are simultaneously drawn, it is necessary to hold drawing data for the plurality of pixel columns in the image display controller, and the cost may increase due to an increase in memory. However, in the method according to the third embodiment, it is only necessary to hold data of adjacent pixels in the same pixel column, so that an increase in cost due to an increase in memory due to overlapping drawing can be minimized.

  In the third embodiment, points other than those described above are the same as those in the first embodiment.

It is a figure which shows roughly the structure of the whole image display apparatus which concerns on Embodiment 1 thru | or 3 of this invention. It is a figure which shows the arrangement | sequence (when combining the laser beam of each color) of the several laser beam in the image display apparatus shown by FIG. It is a figure which shows the arrangement | sequence (when not combining the laser beam of each color) of the several laser beam in the image display apparatus shown by FIG. It is a figure which shows roughly the structure (a laser light source shows only for red) of the image display apparatus which concerns on Embodiment 1 of this invention. 3 is a perspective view schematically showing a configuration of a laser light source of the image display device according to Embodiment 1. FIG. 6 is an explanatory diagram illustrating a laser beam scanning method of the image display apparatus according to Embodiment 1. FIG. It is a figure which shows schematically the structure (The laser light source shows only red use) of the image display apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows schematically the structure of the laser light source of the image display apparatus which concerns on Embodiment 2. FIG. It is a figure which shows schematically the structure (The laser light source shows only red use) of the image display apparatus which concerns on Embodiment 3 of this invention. FIG. 6 is a diagram schematically showing a configuration of a laser light source of an image display device according to a third embodiment. FIG. 10 is an explanatory diagram illustrating a laser beam scanning method of an image display device according to a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source part, 1r Red laser light source, 1g Green laser light source, 1b Blue laser light source, 2 Photosynthesis part, 2r Red dichroic mirror, 2g Green dichroic mirror, 2b Blue dichroic mirror, DESCRIPTION OF SYMBOLS 3 Irradiation lens, 4 Optical scanning part, 5 Projection lens, 6 Screen, 7 Image display controller (display control part), 101 Light emitting element, 102 Drawing light spot, Dm main scanning direction, Ds subscanning direction, Lr red laser light, Lg Green laser light, Lb blue laser light, ROT rotation mirror rotation direction, AX _ROT rotation mirror rotation axis, TILT rotation mirror tilt direction, AX _TILT rotation mirror tilt axis.

Claims (10)

A light source unit having a plurality of light emitting elements to output a plurality of laser beams of the same color;
An optical scanning unit that performs main scanning for moving an irradiation position of a plurality of laser beams from a plurality of light emitting elements of the light source unit in a main scanning direction and sub-scanning for moving an irradiation position by the main scanning in a sub-scanning direction;
A screen that displays an image by receiving laser light that is scanned and sub-scanned by the light scanning unit;
A display control unit that individually modulates the intensity of a plurality of laser beams from a plurality of light emitting elements of the light source unit according to input image data, and controls main scanning and sub-scanning by the optical scanning unit ;
Means for giving a difference in wavelength to a plurality of laser beams of the same color output from a plurality of light emitting elements of the light source unit ,
The display control unit is configured to overlap each pixel displayed on the screen with a plurality of laser beams of the same color output from a plurality of light emitting elements among the plurality of light emitting elements of the light source unit within a period of one frame. An image display device that is controlled so as to be drawn. A light source unit having a plurality of light emitting elements to output a plurality of laser beams of the same color;
An optical scanning unit that performs main scanning for moving an irradiation position of a plurality of laser beams from a plurality of light emitting elements of the light source unit in a main scanning direction and sub-scanning for moving an irradiation position by the main scanning in a sub-scanning direction;
A screen that displays an image by receiving laser light that is scanned and sub-scanned by the light scanning unit;
A display control unit that individually modulates the intensity of a plurality of laser beams from a plurality of light emitting elements of the light source unit according to input image data, and controls main scanning and sub-scanning by the optical scanning unit;
  Means for giving a difference in polarization state to a plurality of laser beams of the same color output from a plurality of light emitting elements of the light source unit,
The display control unit is configured to overlap each pixel displayed on the screen with a plurality of laser beams of the same color output from a plurality of light emitting elements among the plurality of light emitting elements of the light source unit within a period of one frame. To be drawn
An image display device characterized by that. The light source unit includes a first laser light source, a second laser light source, and a third laser light source that output laser beams of different colors,
The first laser light source, the second laser light source, and each of the third laser light source, to claim 1 or 2, characterized by having a plurality of light emitting elements so as to output a plurality of laser light of the same color The image display device described. The image display apparatus according to claim 3 , further comprising a light combining unit configured to combine laser beams output from each of the first laser light source, the second laser light source, and the third laser light source. A plurality of laser beams of the same color to be outputted from the plurality of light emitting elements of the light source unit, according to any one of claims 1 to 4, characterized in that it has a difference in wavelength caused by the variation in characteristics of the light emitting element Image display device.   The plurality of laser beams of the same color output from the plurality of light emitting elements of the light source unit have a difference in polarization state due to characteristic variation of the light emitting elements. The image display device described. A plurality of light emitting elements of the light source unit, according to any one of claims 1 to 6, characterized in that it is arranged to simultaneously draw the plurality of pixels aligned in the sub-scanning direction on the screen Image display device. A plurality of light emitting elements of the light source unit, one of the claims 1 to 6, characterized in that it is arranged to simultaneously draw the plurality of pixels aligned in a direction inclined with respect to the sub scanning direction on the screen The image display device according to claim 1. The image display apparatus according to claim 8 , wherein an arrangement pitch of a plurality of light emitting elements of the light source unit in the sub-scanning direction is the same as an opening diameter of the light emitting elements. A plurality of light emitting elements of the light source unit, according to any one of claims 1 to 6, characterized in that it is arranged to simultaneously draw the plurality of pixels aligned in the main scanning direction on the screen Image display device.

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