JP4751545B2 - Optical scanning image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical scanning type image display apparatus that displays an image by scanning a light beam modulated in accordance with input pixel data.
[0002]
[Prior art]
In recent years, the need for thinner and larger displays has rapidly increased, and the spread of projection-type image display devices (hereinafter referred to as projectors) suitable for large-screen display has become apparent. There are various types of projectors, and an optical scanning projector is one of them, which scans the screen with the laser light while modulating the laser light and displays an image on the screen.
[0003]
As a feature of this optical scanning projector,
-A clear image can be obtained for drawing with a highly directional laser beam.
-Since the laser light source has an ideal single wavelength spectrum distribution, it has excellent color rendering properties, and an extremely high quality color image display is possible.
[0004]
A configuration example of the most general optical scanning projector is schematically shown in FIG. In FIG. 4, (a) shows the optical scanning projector viewed from the side, and (b) shows the optical scanning projector viewed from above (partially omitted). In FIG. 4, R, G, and B are laser light sources that generate laser light of three primary colors of red, green, and blue, respectively. As the laser light sources R, G, and B, various types such as a gas laser and a laser diode can be applied.
[0005]
The laser beams emitted from the laser light sources R, G, and B are modulated by the optical modulators 11 to 13 based on the image signals ARo, AGo, and ABo corresponding to the colors red, green, and blue. For example, an AOM (acousto-optic modulator) is used as the optical modulators 11 to 13. The laser light modulated by the optical modulators 11 and 13 is combined with the laser light reflected by the mirrors 14 and 15 and modulated by the optical modulator 12 by the combining optical element 16 such as a dichroic prism, and is then scanned by one scanning laser. Light is generated.
[0006]
The laser beam synthesized by the synthesis optical element 16 enters the polygon mirror 17. The polygon mirror 17 is a polygonal mirror that is rotationally driven by the polygon motor 18 in the horizontal direction with respect to the incident laser light, and therefore main scans the incident laser light in the horizontal direction. The laser beam reflected by the polygon mirror 17 enters the galvanometer mirror 19. The galvanometer mirror 19 is a mirror that reciprocates in a direction perpendicular to the incident laser beam, and thus sub-scans the incident laser beam in the vertical direction. The laser beam reflected by the galvanometer mirror 19 is guided to the screen 20, and as a result, an image is displayed on the screen 20.
[0007]
As a specific prior art of the optical scanning projector, for example, there is a laser display device described in Japanese Patent No. 2766883. In this laser display device, in order to prevent adjacent pixels from interfering with each other, an off period of scanning light is provided between adjacent pixels, and the light utilization efficiency is improved by making the beam flat.
[0008]
Further, in the above-described optical scanning projector, pixel separation means for separating pixels at least every other pixel in a series of pixels in the scanning direction of the light beam, and subframe generation for generating a subframe for each separated pixel There has been proposed one provided with means and display control means for displaying one screen (frame) by sequentially displaying the sub-frames. In this optical scanning projector, one frame is divided into a plurality of subframes and displayed, and the image of each subframe is thinned out every (NF-1) in the scanning direction with respect to the original image. With this configuration, the response speed substantially required for the light beam modulation is reduced.
[0009]
[Problems to be solved by the invention]
In the above laser display device, since the beam is flattened, it is possible to surely increase the light utilization efficiency. However, as the light utilization efficiency is increased, the above-mentioned off period becomes shorter and the response speed accordingly increases. However, there is a problem that a fast light source or a modulation control system is required. This becomes more prominent as the resolution of the display image increases, and there is a problem that the displayable resolution is significantly limited.
[0010]
Further, in the above optical scanning projector, the frame frequency is substantially lowered, so that the screen luminance is lowered unless a plurality of light beams are provided in the sub scanning direction.
The present invention does not require an increase in response speed even if the light beam is flattened and the off-period of the scanning light between adjacent pixels is shortened. An object is to provide a display device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an optical scanning type image display apparatus that displays an image by scanning a light beam modulated according to input pixel data, in the scanning direction of the light beam. A series of pixels having pixel separation means for separating pixels at least every other pixel, providing a light beam for each pixel separated by the pixel separation means, and simultaneously scanning the plurality of light beams; An image is displayed.
[0012]
According to a second aspect of the present invention, there is provided the optical scanning image display device according to the first aspect, further comprising modulation timing control means for individually controlling the modulation timings of the plurality of light beams. .
[0013]
According to a third aspect of the present invention, in the optical scanning image display device according to the first or second aspect, the on-time of the plurality of light beams during a scanning period of one pixel can be adjusted.
[0014]
According to a fourth aspect of the present invention, in the optical scanning image display device according to the first aspect, a plurality of the plurality of light beams are further provided in a direction intersecting with the scanning direction.
[0015]
The invention according to claim 5 is the optical scanning image display device according to claim 1 or 2, further comprising sub-scanning means for sub-scanning the plurality of light beams in a direction crossing the scanning direction.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 schematically shows an embodiment of the present invention. This embodiment is an example of an optical scanning projector in the case where the number of light beams in the main scanning direction is 2, but the present invention is not limited to this. In this embodiment, the portions that generate the two scanning light beams 21 and 22 are, for example, light beam generation portions (lasers) from the laser light sources R, G, and B to the combining optical element 16 in the optical scanning projector shown in FIG. Two sets of light sources R, G, B, light modulators 11 to 13, mirrors 14 and 15, and a combining optical element 16) are provided.
[0017]
Note that the input signals for modulating the light beams 21 and 22 from the two sets of combining optical elements are two sets of three lights corresponding to the input signals ARo, AGo and ABo to the optical modulators 11 to 13, respectively. The input signals ARo1, AGo1, ABo1 and ARo2, AGo2, ABo2 to the modulator are generated as described later.
[0018]
The two scanning light beams 21 and 22 are incident on a polygon mirror 23 as main scanning means in an array along the rotation direction. The polygon mirror 23 is rotationally driven by a polygon motor (not shown) in the horizontal direction with respect to the incident laser beam. The light beam reflected by the polygon mirror 23 is bent in the vertical direction by the folding mirror 24 and is incident on the galvanometer mirror 25 as the sub-scanning means. The galvanometer mirror 25 is driven by a drive unit (not shown) and reciprocates in a direction perpendicular to the rotation surface of the polygon mirror 23.
[0019]
The light beam reflected by the galvanometer mirror 25 scans the screen 26 in the horizontal direction (main scan) according to the movement of the polygon mirror 23 and simultaneously scans in the vertical direction (sub-scan) according to the movement of the galvanometer mirror 25. A display image is formed on 26. At this time, each light beam displays pixels every other pixel so that the pixels are interpolated with each other for each horizontal line.
[0020]
The two light beams 21 and 22 arranged in the main scanning direction can be arranged in the sub-scanning direction. As a simple configuration, the two light beams 21 and 22 arranged in the main scanning direction may be provided by the number of display lines. In this case, the galvanometer mirror 25 can be omitted and the light reflected from the polygon mirror 23 can be drawn directly on the screen 26. Further, the polygon mirror 23 may be omitted, and the galvano mirror 25 may be disposed at the position, and the light beam may be moved so as to simultaneously scan all lines in the horizontal direction.
[0021]
FIG. 2 schematically shows the configuration of a control system for generating an input signal to the optical modulator in this embodiment. FIG. 2 shows only the control system for the red image signal, but the control systems for the other colors (green and blue) are exactly the same, and the description thereof is omitted.
[0022]
The signal Ri is a red analog image signal input, and is amplified to an appropriate level by the amplifier 27. Signals VD and HD are vertical and horizontal synchronizing signal inputs corresponding to the input image signal, respectively. The synchronization signal extraction circuit 28 reproduces and outputs the synchronization clock (clock synchronized with the pixel signal) RCK of the image signal Ri from the input synchronization signals VD and HD.
[0023]
The image signal ARi from the amplifier 27 is input to the A / D converter 29 and converted into a digital image data signal DRi in synchronization with the synchronization clock RCK. The write address generation circuit 30 detects the number of scanning lines by counting the number of horizontal synchronization signal pulses in one frame period based on the input synchronization signals VD and HD and detects one horizontal period from the synchronization signal RCK from the synchronization signal extraction circuit 28. By detecting the number of effective pixels, a write address signal WAD to subframe memories 31 and 32 described later is generated and output.
[0024]
Here, the write address signal WAD includes a horizontal address portion corresponding to the main scanning direction and a vertical address portion corresponding to the sub scanning direction. The horizontal address value is incremented by 1 every time the synchronization clock RCK from the synchronization signal extraction circuit 28 is counted 2 times from the first pixel in one line in the write address generation circuit 30, and the clock count up to the last pixel in one line is counted. Reset when finished. The vertical address value is incremented by 1 every time the horizontal address value is reset in the write address generation circuit 30, and is reset when the clock count up to the last pixel of the last line is completed and becomes the first pixel address value. Return.
[0025]
The image separation control circuit 33 generates and outputs write control signals WEN1 and WEN2 to the subframe memories 31 and 32 based on the write address signal WAD from the write address generation circuit 30 and the synchronization clock RCK from the synchronization signal extraction circuit 28. . The value of the write control signal WEN1 is toggled every cycle of the synchronous clock RCK, and is reset in synchronization with the reset timing of the horizontal address value. The write control signal WEN2 is an inverted version of the write control signal WEN1.
[0026]
The subframe memories 31 and 32 receive the image data DRi from the A / D converter 29 from the write address generation circuit 30 when the write control signals WEN1 and WEN2 from the image separation control circuit 33 are at “H” level, respectively. In accordance with the write address signal WAD, data is sequentially written in synchronization with the synchronization signal RCK from the synchronization signal extraction circuit 28. As a result, sequentially inputted image data Ri is written alternately in the two subframe memories 31 and 32 in the horizontal direction. The subframe memories 31 and 32 are memories having a dual port function that can be read asynchronously with the write system by read address signals RAD1 and RAD1 described later.
[0027]
The read clock generation circuit 34 divides the reference clock OCK to generate a plurality of clocks having different phases. In FIG. 2, the read clock generation circuit 34 divides the reference clock OCK by 1/8 and generates eight clocks CK7 to CK0 that are sequentially shifted in phase by one period of the reference clock OCK. . The clock selection circuit 35 selects two clocks from the input clocks CK7 to CK0 from the read clock generation circuit 34 based on a control signal CTL1 generated by a remote controller (not shown) or the like as clocks TCK1 and TCK2. Output.
[0028]
The read address generation circuits 36 and 37 generate data read address signals RAD1 and RAD2 from the subframe memories 71 and 72 in synchronization with the read clocks TCK1 and TCK2 from the clock selection circuit 35, respectively. The image data DR1 and DR2 are read from the subframe memories 31 and 32 in accordance with the read address signals RAD1 and RAD2 from the read address generation circuits 36 and 37, and the image data DR1 and DR2 are input to the output gate circuits 38 and 39. The
[0029]
The output gate circuits 38 and 39 output the image data DR1 and DR2 from the subframe memories 31 and 32 only during a period in which control signals ENO1 and ENO2 described later are at “H” level, respectively, and the control signals ENO1 and ENO2 are “L”. When “level”, “zero” is output as image data. The output control circuits 40 and 41 set the output signals ENO1 and ENO2 to the “H” level at each rising transition of the clocks TCK1 and TCK2 from the clock selection circuit 35, respectively, and control signals CTL2 generated by a remote controller (not shown) or the like. The output signals ENO1 and ENO2 are set to the “L” level after a predetermined time set based on them.
[0030]
Output signals DRo1 and DRo2 of the output gate circuits 38 and 39 are input to the D / A converters 42 and 43, respectively, and converted into analog signals and output. The analog output signals ARo1 and ARo2 from the D / A converters 42 and 43 are respectively sent to corresponding optical modulators (one optical modulator in each of the two sets of three optical modulators). Input and modulate the laser beam.
[0031]
As the laser light source, for example, an LD (laser diode) that can be directly modulated can be used. In such a case, analog output signals ARo1 from the D / A converters 42 and 43, ARo2 is input directly to the light source. Here, the analog output signals ARo1 and ARo2 from the D / A converters 42 and 43 are read out from the input clocks CK7 to CK0 from the read clock generation circuit 34 by the clock selection circuit 35 by the control signal CTL1 from the remote controller or the like. The timing can be adjusted by arbitrarily selecting TCK1 and TCK2, and the "H" level period of the control signals ENO1 and ENO2 can be arbitrarily set by the control signal CTL2 from the remote controller or the like, during one pixel scanning period The on-time of the scanning light beam can be controlled.
[0032]
According to this embodiment, the pixel separation means (the control system shown in FIG. 2) for separating the pixels at every other pixel in the series of pixels in the scanning direction of the light beam is provided, and separation is performed by the pixel separation means. Since light beams 21 and 22 are provided for each pixel to be displayed and an image is displayed by simultaneously scanning the plurality of light beams 21 and 22, the light beam is flattened so that the scanning light is turned off between adjacent pixels. Even if the length is shortened, it is not necessary to increase the response speed, and the luminance is not lowered due to the reduction of the frame frequency.
[0033]
In addition, if a plurality of light beams provided in the scanning direction are arranged with high accuracy according to a desired pixel interval, a high-precision design or mounting technique is required for a mechanical system or an optical system, which increases the cost. Arise. However, according to this embodiment, the modulation timing control means (such as the clock selection circuit 35 and the remote controller) that individually controls the modulation timings of the plurality of light beams is provided. Even if the interval is different from the desired pixel interval, it can be corrected.
[0034]
In addition, the shape of the light beam, the number and size of display pixels, the scanning speed, etc. vary depending on the specifications of the apparatus or the display image, and the optimum on-time of the light beam during one pixel scanning period also differs in relation to these items. Come. According to this embodiment, since the ON time of the plurality of light beams 21 and 22 during the scanning period for one pixel can be adjusted by a remote controller or the like, the light beam can be applied to any device or display image. Optimal on-time can be set, and good display quality is always obtained.
[0035]
FIG. 3 shows a part of a control system for generating an input signal to the optical modulator in another embodiment of the present invention. In this embodiment, in the above embodiment, the two light beams 21 and 22 arranged in the main scanning direction are also provided in the sub-scanning direction to form two columns, and two lines are scanned simultaneously. That is, two sets of optical scanning systems that simultaneously scan in the main scanning direction the same line on the screen 26 with the two light beams 21 and 22 arranged in the main scanning direction are provided. These scanning systems alternately scan each line on the screen 26 by simultaneously scanning two adjacent lines on the screen 26 in the main scanning direction. FIG. 3 shows only the control system for the red image signal, but the control systems for the other colors (green and blue) are exactly the same, and the description thereof is omitted. Further, in FIG. 3, the illustration of the same configuration as in FIG. 2 in the preceding stage is omitted.
[0036]
In the subframe memories 311, 312, 321, and 322, the subframe memories 311 and 312 correspond to the two light beams on the first line, and the subframe memories 321 and 322 correspond to the light beam on the second line. ing. Based on the write address signal WAD from the write address generation circuit 30 and the synchronization clock RCK from the synchronization signal extraction circuit 28, the pixel separation control circuit 33a performs a horizontal write control signal HWEN1, HWEN2 and write control signals VWEN1 and VWEN2 for the vertical direction are generated. The write control signals HWEN1 and HWEN2 are the same as the write control signals WEN1 and WEN2 in FIG. On the other hand, the write control signals VWEN1 and VWEN2 toggle each time the horizontal address value is reset, and are reset in synchronization with the reset timing of the vertical address value.
[0037]
The subframe memory 311 receives write control signals HWEN1 and VWEN1 from the pixel separation control circuit 33a, the subframe memory 312 receives write control signals HWEN2 and VWEN1 from the pixel separation control circuit 33a, and the subframe memory 321 controls pixel separation control. Write control signals HWEN1 and VWEN2 are input from the circuit 33a, and the write control signals HWEN2 and VWEN2 are input to the subframe memory 312 from the pixel separation control circuit 33a.
[0038]
The subframe memories 311, 312, 321, and 322 write image data DRi from the A / D converter 29 when the write control signals HWEN 1 or HWEN 2 and VWEN 1 or VWEN 2 are both at “H” level, respectively. Are sequentially written in synchronization with the synchronization signal RCK from the synchronization signal extraction circuit 28 in accordance with the write address signal WAD from. As a result, the sequentially input image data Ri are written alternately in the subframe memories 311 and 312 and 321 and 322 in the horizontal direction, and at the same time, the corresponding subframe memories 311 and 321 in the vertical direction are also written. , 312 and 322 are alternately written. Also in this embodiment, the subframe memories 311, 312, 321, and 322 are memories having a dual port function that can be read asynchronously with the write system by read address signals RAD1 and RAD2 described later.
[0039]
The image data DR11 and DR21 are read from the subframe memories 311 and 321 according to the read address signal RAD1 from the read address generation circuit 36, and the image data DR12 and DR22 are read from the subframe memories 312 and 322 according to the read address signal RAD2. These image data DR11 to DR22 are input to output gate circuits 381, 382, 391, 392, respectively.
[0040]
The output gate circuits 381, 382, 391 and 392 are subframe memories 311, 312, 321 and 322 only during the period when the control signals ENO1 and ENO2 from the output control circuits 40 and 41 similar to FIG. Image data DR11, DR12, DR21, DR22 are output, and when the control signals ENO1, ENO2 are "L", "zero" is output as image data. Output signals DRo11 to DRo22 from the output gate circuits 381, 382, 391, and 392 are input to D / A converters 421, 422, 431, and 432, respectively, and converted into analog signals ARo11 to ARo22.
[0041]
The analog output signals ARo11 to ARo22 are output from corresponding optical modulators (one optical modulator in each of the two sets of three optical modulators for modulating the light beam that scans the same line). Each of the two sets of three optical modulators for modulating the light beam that scans the same line is input to each of the optical modulators) to modulate the laser light. As described above, as the laser light source, for example, an LD (laser diode) that can be directly modulated can be used. In such a case, the D / A converters 421, 422, 431, and 432 are used. Output signals DRo11 to DRo22 are directly input to the light source.
[0042]
Here, the output signals Aro11 to Aro22 from the D / A converters 421, 422, 431, and 432 are read by the clock selection circuit 35 according to the control signal CTL1 from the remote controller or the like, and are input clocks CK7 to CK0 from the clock generation circuit 34. The timing can be adjusted by arbitrarily selecting the clocks TCK1 and TCK2 from among them. Furthermore, the “H” level period of the control signals ENO1 and ENO2 can be arbitrarily set by the control signal CTL2 from the remote controller or the like to scan one pixel. The on-time of the scanning light beam during the period can be controlled.
[0043]
In this embodiment, the output signals Aro11 to Aro22 from the D / A converters 421, 422, 431, and 432 use ARo11 and Aro21 or ARo12 and ARo22 as the same modulation timing, but the present invention is not limited to this. It is also possible to arbitrarily set the modulation timing for each of the light beams.
[0044]
According to this embodiment, since a plurality of light beams are further provided in the sub-scanning direction intersecting with the main scanning direction, the light source or modulation control is performed by reducing the modulation frequency when displaying a two-dimensional image. The response speed required for the system can be reduced. As a straightforward example of the present invention, when displaying an image in which the number of pixels in the main scanning direction is M and the number of lines in the sub-scanning direction intersecting the main scanning direction is N, the light beam is output by the number of lines N. Provide.
[0045]
Further, according to this embodiment, since the plurality of light beams are further provided with the sub-scanning means (galvano mirror 25) for sub-scanning in the sub-direction intersecting with the main scanning direction, the response speed required for the light source or the modulation control system. In addition, it is possible to provide an optical scanning type image display apparatus in a form different from that in which the same number of light beams as the number N of lines of the display image are provided. That is, when the generation cost per light beam is high, there is a problem that the cost becomes extremely high if the same number of light beams as the number N of lines are provided. In this embodiment, the number of light beams, the main scanning system, The combination of sub-scanning systems can be optimized to improve cost performance.
[0046]
【The invention's effect】
As described above, according to the first aspect of the present invention, even if the light beam is flattened and the scanning light OFF period between adjacent pixels is shortened, the response speed is not increased, and the frame frequency is reduced. Does not cause a decrease in brightness.
According to the second aspect of the present invention, even if the light beam interval in the scanning direction is different from the desired pixel interval, it can be corrected.
[0047]
According to the third aspect of the present invention, the optimum on-time of the light beam can be set for any device or display image, and good display quality can always be obtained.
According to the fourth aspect of the present invention, the response frequency required for the light source or the modulation control system can be reduced by reducing the modulation frequency when displaying a two-dimensional image.
According to the fifth aspect of the invention, the number of light beams and the combination of the main scanning system and the sub-scanning system can be optimized to improve cost performance.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing an embodiment of the present invention.
FIG. 2 is a block diagram schematically showing a configuration example of a control system for generating an input signal to the optical modulator in the embodiment.
FIG. 3 is a block diagram showing a part of a control system for generating an input signal to an optical modulator in another embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a configuration example of the most general optical scanning projector.
[Explanation of symbols]
21, 22 Light beam 23 Polygon mirror 25 Galvano mirror 26 Screen 27 Amplifier 28 Synchronization signal extraction circuit 29 A / D converter 30 Write address generation circuit 31, 32 Subframe memory 33, 33a Image separation control circuit 34 Read clock generation circuit 35 Clock selection circuits 36, 37 Read address generation circuits 38, 39 Output gate circuits 40, 41 Output control circuits 42, 43 D / A converters 311, 312, 321, 322 Subframe memories 381, 382, 391, 392 Output gate circuits 421, 422, 431, 432 D / A converter

Claims (5)

In an optical scanning image display device that displays an image by scanning a light beam modulated in accordance with input pixel data, the pixel is separated at least every other pixel in a series of pixels in the scanning direction of the light beam. An optical scanning type image display apparatus comprising: a pixel separating unit configured to provide a light beam for each pixel separated by the pixel separating unit, and simultaneously scanning the plurality of light beams. . 2. The optical scanning image display apparatus according to claim 1, further comprising modulation timing control means for individually controlling the modulation timings of the plurality of light beams for each of the light beams. . 3. The optical scanning image display apparatus according to claim 1, wherein an on-time of the plurality of light beams during a scanning period of one pixel can be adjusted. 2. The optical scanning image display apparatus according to claim 1, wherein a plurality of the plurality of light beams are further provided in a direction intersecting with the scanning direction. 3. The optical scanning image display apparatus according to claim 1, further comprising sub-scanning means for sub-scanning the plurality of light beams in a direction crossing the scanning direction.

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