JP5854120B2 - Display device - Google Patents

Description

  The present invention relates to a display device, and more particularly, to a display device including a laser light generation unit that outputs laser light.

  2. Description of the Related Art Conventionally, a display device including a laser light generation unit that outputs laser light is known (see, for example, Patent Document 1).

  In the above-mentioned Patent Document 1, generation of speckle noise (white spot-like unevenness appearing in a projection target part) caused by interference between a laser light source (laser light generation part) that outputs laser light and laser light interferes. A laser marking device (display device) is disclosed that includes a liquid crystal spatial light modulator that converts the phase of laser light for reduction. In the laser marking device according to Patent Document 1, the laser light source continues to output laser light and the phase of the laser light is converted by passing the output laser light through a liquid crystal spatial light modulator, thereby causing speckle noise. It is comprised so that generation | occurrence | production of this can be reduced.

Japanese Patent No. 3475947

  However, in the laser marking device according to Patent Document 1, the generation of speckle noise is reduced by converting the phase of the laser beam by passing the laser beam output from the laser light source through the liquid crystal spatial light modulator. In addition, a dedicated liquid crystal spatial light modulator for converting the phase of the laser beam is necessary, and the configuration of the laser marking device (display device) is complicated.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a display device capable of reducing the occurrence of speckle noise with a simple configuration. That is.

Means for Solving the Problems and Effects of the Invention

  A display device according to one aspect of the present invention includes a laser light generation unit that outputs laser light, a projection unit that projects an image including a plurality of image forming elements on an arbitrary projection region by scanning the laser light, A first laser beam including a relaxation oscillation region in which the output of the laser beam becomes unstable at an early stage of laser oscillation with respect to a predetermined position image forming element arranged at a predetermined position among the plurality of image forming elements; And a control unit that performs control to output the second laser light that does not include a vibration region while switching the second laser light for each predetermined number of frames of an image including a plurality of image forming elements.

  In the display device according to one aspect of the present invention, as described above, the output of the laser beam is not output to the predetermined position image forming element arranged at the predetermined position among the plurality of image forming elements at the initial stage of laser oscillation. Control that outputs the first laser beam including a region of relaxation oscillation that becomes stable and the second laser beam that does not include a region of relaxation oscillation while switching for each predetermined number of frames of an image composed of a plurality of image forming elements. A control unit is provided. As a result, it is possible to suppress the occurrence of laser beam interference due to the first laser beam that is not in a stable wavelength including the region of relaxation oscillation, so that the generation of speckle noise can be effectively reduced. . Unlike the configuration in which a dedicated liquid crystal spatial light modulator for converting the phase of the laser beam is provided by reducing the generation of speckle noise by using the relaxation oscillation region of the first laser beam, the control is performed. Since the generation of speckle noise can be easily reduced by simply performing control to output the first laser beam including the region of relaxation oscillation by the unit, it is possible to prevent the apparatus configuration from becoming complicated. it can. As a result, this display device can reduce the occurrence of speckle noise with a simple configuration. Further, by performing control to output the second laser light that does not include the region of relaxation oscillation, in addition to the first laser light with unstable output, the second laser light with stable output is also output. As compared with the case where only the first laser beam whose output is unstable is output, it is possible to suppress the luminance of the image projected on the projection region from being lowered.

  In the display device according to the one aspect described above, preferably, the control unit outputs the first laser beam and the second laser beam to the predetermined position image forming element while switching at random for each predetermined number of frames. Is configured to do.

  In the display device according to the above aspect, the control unit preferably arranges the first laser beam and the second laser beam with respect to the predetermined position image forming element in a predetermined arrangement set in advance for each predetermined number of frames. It is configured to perform output control while switching based on patterns.

  In the configuration in which the first laser beam and the second laser beam are switched based on a predetermined arrangement pattern, preferably, the predetermined arrangement pattern is a frame period including a number of frames that is a multiple of the predetermined number of frames. The first laser beam is output at least once to each of the plurality of image forming elements.

  In the configuration in which the first laser beam and the second laser beam are switched based on a predetermined arrangement pattern, it is preferable to further include a storage unit that stores the predetermined arrangement pattern.

  In the display device according to the above aspect, the predetermined number of frames is preferably one.

It is the figure which showed the use condition of the portable projector by 1st Embodiment of this invention. 1 is a block diagram showing a configuration of a portable projector according to a first embodiment of the present invention. It is the block diagram which showed the structure of the laser control part of the portable projector by 1st Embodiment of this invention. 6 is a timing chart showing the relationship between the current of the laser diode and the light output when outputting the laser light including the relaxation oscillation region of the portable projector according to the first embodiment of the present invention. 5 is a timing chart showing the relationship between the current of the laser diode and the light output when outputting the laser light not including the relaxation oscillation region of the portable projector according to the first embodiment of the present invention. It is a schematic diagram for demonstrating the example which changes the position of the pixel to which a laser beam is output at random in the portable projector by 1st Embodiment of this invention. It is the block diagram which showed the structure of the laser control part of the portable projector by 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the example which changes the position of the pixel to which a laser beam is output in the portable projector by 2nd Embodiment of this invention corresponding to an arrangement pattern. It is a figure for demonstrating the order in which an arrangement | positioning pattern is selected in the portable projector by 2nd Embodiment of this invention. It is the block diagram which showed the structure of the laser control part of the portable projector by 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the example which reduces the memory capacity of the memory of the portable projector by 3rd Embodiment of this invention. It is the block diagram which showed the structure of the laser control part of the portable projector by 4th Embodiment of this invention. It is a schematic diagram for demonstrating the relationship between the range which the scanner mirror of the portable projector by 4th Embodiment of this invention drives, and the angular velocity which drives. It is a schematic diagram for demonstrating the arrangement pattern in case the ratio of the laser beam containing the area | region of the relaxation oscillation of the portable projector by 4th Embodiment of this invention differs in a scanning direction. It is the block diagram which showed the structure of the laser control part of the portable projector by 5th Embodiment of this invention. In the portable projector according to the fifth embodiment of the present invention, it is a diagram for explaining an example in which the output of laser light including a region of relaxation oscillation is different for each of red LD, blue LD, and green LD.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

(First embodiment)
First, the configuration of the portable projector 100 according to the first embodiment will be described with reference to FIGS. The portable projector 100 is an example of the “display device” in the present invention.

  As shown in FIG. 1, the portable projector 100 according to the first embodiment of the present invention projects red, green, and blue laser beams (RGB laser beams) onto a projection range 2 composed of an XY plane. It is configured. Further, the portable projector 100 is configured to be able to project a video (image) composed of a plurality of pixels (image forming elements) onto the projection range 2 by scanning with RGB laser light. Further, the portable projector 100 is connected to the personal computer 3 via the video input interface 10 (see FIG. 2), so that the video input from the personal computer 3 is projected onto the projection range (screen) 2. It is configured. In addition, the portable projector 100 is configured so that it can be used while being carried by the user 4.

  Next, the configuration of the portable projector 100 will be described. As shown in FIG. 2, the portable projector 100 includes an image processing unit 11, a red laser diode (red LD) 12 capable of outputting red laser light, and a blue laser diode (blue color) capable of outputting blue laser light. LD) 13, a green laser diode (green LD) 14 capable of outputting green laser light, a laser control unit 15, and a laser driver 16. The red LD 12, the blue LD 13, and the green LD 14 are examples of the “laser light generator”, and the “red laser light generator”, “blue laser light generator”, and “green laser light generator” of the present invention, respectively. Part "is an example. The laser controller 15 and the laser driver 16 are examples of the “controller” of the present invention. Further, the portable projector 100 includes one scanner mirror 17, a scanner mirror control unit 18, a scanner mirror driver 19 that drives the scanner mirror 17, and a photodetector 20 that detects the gradation of RGB laser light. It has more. As an optical system of the portable projector 100, two half mirrors 21 and 22 and a lens 23 are provided in addition to the red LD 12, the blue LD 13, the green LD 14, the scanner mirror 17, and the photodetector 20. . These components of the portable projector 100 are accommodated in a projector body (housing) 1 (see FIG. 1).

  The video processing unit 11 is configured to transmit video signal data to the laser control unit 15 at predetermined time intervals based on the video signal input from the personal computer 3 (see FIG. 1). Thereby, the laser control unit 15 can recognize pixel (image forming element) information at a predetermined scanning position.

  Here, in the first embodiment, the laser control unit 15 controls the laser driver 16 in order to project an image including a plurality of pixels on the projection range 2 based on the pixel information recognized by the image processing unit 11. It is configured as follows. Further, the laser control unit 15 is configured to perform processing for reducing speckle noise generated in an image projected on the projection range 2 due to interference of laser light having a stable wavelength. Further, the laser controller 15 includes a laser beam (including a region that is driven so as to reduce speckle noise) including a relaxation vibration region described later (see FIG. 4), and does not include a relaxation vibration region (normally). The position where the laser beam including the region of relaxation oscillation is output and the region of relaxation oscillation for each frame of the image composed of the predetermined pixels from which the laser beam (see FIG. 5) is output. The position where the laser beam not including the light is output is selected at random and changed.

  Specifically, as shown in FIG. 3, the laser control unit 15 includes a speckle noise reduction pixel selection circuit 15a as a random pattern generation circuit and a laser drive current generation circuit 15b. The speckle noise reduction pixel selection circuit 15a is a predetermined pixel in an image that uses either a laser beam including a relaxation oscillation region (see FIG. 4) or a laser beam not including a relaxation oscillation region (see FIG. 5). Has a function of selectively outputting to. Further, as shown in FIG. 6, the speckle noise reduction pixel selection circuit 15a is a laser including a region of relaxation oscillation with respect to pixels selected by selecting approximately 33% of all pixels in one frame at random. It is configured to perform control to output light.

  That is, in the first embodiment, the laser control unit 15 generates a random pattern so that about 33% (1/3) of pixels are selected as pixels for reducing speckle noise for each frame, Based on the generated random pattern, a pixel that reduces speckle noise is selected, and laser light including a region of relaxation oscillation is output to the selected pixel. Thereby, the pixel which reduces speckle noise for every frame is changed. In this case, it is possible to disperse (average) a region where generation of speckle noise is suppressed in a long frame period composed of a plurality of frames. Note that the generated random pattern is not related to each frame, and the position of a pixel that outputs laser light including a region of relaxation oscillation may overlap between frames. The laser beam including the relaxation oscillation region is an example of the “first laser beam” in the present invention, and the laser beam not including the relaxation oscillation region is an example of the “second laser beam” in the present invention. . A pixel that outputs laser light including a region of relaxation vibration is an example of the “first image forming element” in the present invention, and a pixel that outputs laser light not including a region of relaxation vibration is “ It is an example of a “second image forming element”. One frame is an example of the “predetermined number of frames” in the present invention.

By configuring the speckle noise reduction pixel selection circuit 15a as described above, the laser drive current generation circuit 15b receives the signal output from the speckle noise reduction pixel selection circuit 15a and responds to the received signal. The laser driver 16 can output a laser drive current waveform of a laser beam including a relaxation oscillation region or a laser beam not including a relaxation oscillation region. Further, the laser driver 16 is configured to drive the red LD 12, the blue LD 13, and the green LD 14 based on the control by the laser control unit 15 described above. Specifically, when the laser driver 16 outputs laser light including a region of relaxation oscillation, the laser driver 16 has an oscillation threshold current I _th (see FIG. 4) or more with respect to the red LD 12, the blue LD 13, and the green LD 14. control supplies the magnitude of the current, and is configured to repeatedly perform the control to reduce the current to a size of less than the oscillation threshold current I _th. The laser driver 16, when outputting a laser beam including the area of the relaxation oscillation, by controlling to decrease the current to the single lasing threshold current I _th less than the size per one pixel, the laser The light output is configured to stop. Further, when the laser driver 16 outputs a laser beam that does not include a relaxation oscillation region, the laser driver 16 has a magnitude greater than or equal to the oscillation threshold current I _th (see FIG. 5) for the red LD 12, the blue LD 13, and the green LD 14. It is comprised so that the control which continues supplying the electric current of may be performed.

Further, the red LD 12, the blue LD 13 and the green LD 14 have the characteristics of a general laser diode as shown in FIGS. 4 and 5, respectively. That is, the red LD 12, blue LD13 and green LD14, respectively, when the current supplied is a constant value (oscillation threshold current _{I th)} above, emission by stimulated emission takes place. Thus, the red LD 12, when the oscillation threshold current _{I th} or more current is supplied to the blue LD13 and green LD14, it is possible to output a laser beam. The red LD 12, when a current of less than the oscillation threshold current _{I th} is supplied to the blue LD13 and green LD 14, it is possible to stop the output of the laser beam. Each of the red LD 12, the blue LD 13, and the green LD 14 is configured to output laser light having a high luminance as the supplied current value increases.

  Here, in the first embodiment, the laser light output from the red LD 12, the blue LD 13, and the green LD 14 is an oscillation phenomenon in which the shape of the laser light output becomes a waveform shape at the initial stage of laser oscillation, as shown in FIG. Indicates. This waveform shape shows a shape that gradually attenuates as the time for outputting the laser beam elapses, and the oscillation phenomenon in which the laser beam becomes unstable at the initial oscillation of the laser is called relaxation oscillation. This relaxation oscillation converges to a constant output when a predetermined period (about 3 nsec) elapses. In the relaxation oscillation region, the shape of the laser beam output is a wave shape, so that interference with other laser beams can be mitigated. As a result, speckle noise (white dots appearing on the projection area) It is possible to suppress the occurrence of unevenness. Therefore, the portable projector 100 according to the first embodiment is configured to reduce the generation of speckle noise by outputting laser light including a region of relaxation vibration. In the first embodiment, the period during which the output of the laser light after relaxation oscillation is stable is set to be longer than the predetermined period of relaxation oscillation.

  One scanner mirror 17 is a small oscillating mirror element that is driven around a X axis and a Y axis by a scanner mirror driver 19 and can vibrate at a predetermined deflection angle. Thereby, it is possible to scan in the X direction and the Y direction. The scanner mirror control unit 18 is configured to control the scanner mirror driver 19 based on pixel information at a predetermined scanning position recognized by the video processing unit 11. That is, the scanner mirror 17 scans the RGB laser light in a zigzag manner (in the X direction (see FIG. 1) while shifting the height position in the Y direction) over the entire projection range 2 based on the control by the scanner mirror control unit 18. It is comprised so that it may vibrate. The scanner mirror 17 is an example of the “projection unit” in the present invention.

  The photodetector 20 is arranged so that laser light can be detected from the red LD 12, the blue LD 13, and the green LD 14. The light detector 20 is connected to the laser control unit 15 and is configured to output the detected gradation of the laser light to the laser control unit 15. In addition, the laser control unit 15 determines whether or not the gradation is correct based on the gradation input from the light detector 20 in comparison with the pixel information at the scanning position. The output (luminance) of the red LD 12, blue LD 13 and green LD 14 is adjusted so as to obtain correct gradation.

  Next, the configuration of the optical system of the portable projector 100 will be described. As shown in FIG. 2, the half mirror 21 is disposed at a position where the blue laser beam and the green laser beam intersect at a right angle. The half mirror 21 is configured to transmit blue laser light and reflect green laser light. The half mirror 22 is disposed at a position where the blue laser light, the green laser light, and the red laser light that have passed through the half mirror 21 intersect at right angles. The half mirror 22 reflects part of the blue laser light and green laser light to the photodetector 20 side, and transmits the remainder other than part of the blue laser light and green laser light to the lens 23 side. It is configured as follows. The half mirror 22 is configured to transmit a part of the red laser light to the photodetector 20 side and reflect the remaining part of the red laser light other than a part to the lens 23 side. Further, the lens 23 has a function of making RGB laser light having a predetermined gradation by aligning the optical axes of red laser light, blue laser light, and green laser light. In addition, the RGB laser light whose optical axes are aligned in the lens 23 is configured to be scanned toward the projection range 2 by being reflected by the scanner mirror 17.

  In the first embodiment, as described above, for some of the plurality of image forming elements (pixels), a laser including a region of relaxation oscillation in which the output of laser light becomes unstable at the initial stage of laser oscillation. By controlling the output of light, it is possible to suppress the occurrence of laser beam interference due to laser light that is not a stable wavelength including the region of relaxation oscillation. Can be reduced. In addition, a configuration in which a dedicated liquid crystal spatial light modulator or the like for converting the phase of the laser beam is provided by reducing the generation of speckle noise using the relaxation oscillation region of the laser beam including the relaxation oscillation region. In contrast, the generation of speckle noise can be easily reduced simply by controlling the laser control unit 15 and the laser driver 16 to output laser light including the relaxation oscillation region, so that the configuration of the apparatus is complicated. Can be suppressed. As a result, the portable projector 100 can reduce the occurrence of speckle noise with a simple configuration. In addition, laser light including a region of relaxation oscillation in which laser light output becomes unstable at the initial stage of laser oscillation is output to some of the plurality of image forming elements (pixels), and a plurality of images By performing control to output laser light that does not include the relaxation oscillation region to pixels other than some of the forming elements (pixels), the laser light including the relaxation oscillation region where the output is unstable is changed. In addition, since laser light that does not include a region of relaxation oscillation with a stable output is also output, it is projected onto the projection region compared to the case of outputting only laser light that includes a region of relaxation oscillation with unstable output. It can suppress that the brightness | luminance of the image to be reduced falls.

  In the first embodiment, as described above, for each frame of an image composed of a plurality of pixels, a pixel that outputs a laser beam including a relaxation oscillation region and a laser beam that does not include a relaxation oscillation region are output. By changing the position of the pixel to be changed, the area where speckle noise is suppressed is dispersed (averaged) over the entire image by switching the frame, so that the speckle noise can be effectively reduced over the entire image. Generation can be reduced.

  In the first embodiment, as described above, for each frame of an image composed of a plurality of pixels, a pixel that outputs a laser beam including a relaxation oscillation region and a laser beam that does not include a relaxation oscillation region are output. By selecting the position of the pixel to be randomly selected, the position of the pixel from which the laser beam including the relaxation oscillation region is output and the position of the pixel from which the laser beam not including the relaxation oscillation region is output are determined for each frame of the image. By changing the position of the pixel that outputs laser light that includes the relaxation oscillation region and the pixel that outputs laser light that does not include the relaxation oscillation region, it is easy to relax by changing the position of the pixel at random. It is possible to prevent the position of the pixel from which the laser light including the vibration region is output and the position of the pixel from which the laser light not including the relaxation vibration region is output from being fixed at the same position. That. Further, for each frame of the image, by randomly selecting and changing the position of the pixel that outputs the laser light including the relaxation vibration region and the pixel that outputs the laser light not including the relaxation vibration region, There is no need to provide a memory or the like for storing an arrangement pattern of positions of pixels that output a laser beam including a relaxation oscillation region and pixels that output a laser beam that does not include a relaxation oscillation region.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. In the portable projector according to the second embodiment, the position of a pixel that outputs laser light including a relaxation vibration region and a pixel that outputs laser light that does not include a relaxation vibration region are randomly selected for each frame. Unlike the first embodiment, which is changed in this manner, a pixel that outputs a laser beam including a relaxation oscillation region and a laser beam that does not include a relaxation oscillation region are output based on a preset pixel arrangement pattern. An example in which the position of a pixel to be changed is described.

  In the second embodiment, as shown in FIG. 7, the laser control unit 115 includes an arrangement pattern generation circuit 115a and a memory 115b that stores arrangement patterns (patterns 1, 2, and 3) generated by the arrangement pattern generation circuit 115a. And a pattern selection circuit 115c for selecting an arrangement pattern from the memory 115b. The laser control unit 115 includes a laser beam including a preset relaxation vibration region (including a region driven to reduce speckle noise) and does not include a relaxation vibration region (only a normal drive region). Based on the arrangement pattern of pixels that output laser light, laser light that includes a preset relaxation vibration region and laser light that does not include a relaxation vibration region are output for each frame of an image. The pixel position is changed. The memory 115b is an example of the “storage unit” in the present invention.

  The arrangement pattern generation circuit 115a has a function of generating an arrangement pattern (see FIG. 8) of pixels that output laser light including a relaxation vibration region and laser light not including a relaxation vibration region. Further, as shown in FIG. 8, the arrangement pattern generation circuit 115a performs control to output the laser beam including the region of relaxation oscillation substantially uniformly at a rate of about 33% (1/3) per frame of the video. It is configured as follows. The arrangement pattern generation circuit 115a is configured to generate arrangement patterns for 3 (n = 3) frames. In this way, when it is set to generate an arrangement pattern in which laser light including a region of relaxation oscillation per frame is included at a ratio of approximately 33% (1 / n = 1/3), 1 During a frame period composed of 3 (n = 3) times the number of frames, laser light including a region of relaxation oscillation is output once for all pixels. In the case of the second embodiment, the arrangement pattern is configured so that laser light including a region of relaxation oscillation is output at least once for all the pixels in the image. The laser beam including the relaxation oscillation region is an example of the “first laser beam” in the present invention, and the laser beam not including the relaxation oscillation region is an example of the “second laser beam” in the present invention. . A pixel that outputs laser light including a region of relaxation vibration is an example of the “first image forming element” in the present invention, and a pixel that outputs laser light not including a region of relaxation vibration is “ It is an example of a “second image forming element”. One frame is an example of the “predetermined frame” in the present invention.

  In the second embodiment, the memory 115b has a function of storing the arrangement pattern generated by the arrangement pattern generation circuit 115a. Further, as shown in FIG. 9, the pattern selection circuit 115c has a function of selecting an arrangement pattern from the memory 115b in the order of pattern 1, pattern 2, and pattern 3. Then, as shown in FIG. 7, the laser control unit 115 outputs a laser driving current waveform based on the video data output from the video processing unit 11 and the arrangement pattern selected by the pattern selection circuit 115c to the laser driver 16. It is configured to perform control.

  In the second embodiment, as described above, a laser including a relaxation oscillation region in which the output of laser light becomes unstable at the initial stage of laser oscillation for some of the plurality of image forming elements (pixels). By performing the light output control, the generation of speckle noise can be reduced with a simple configuration as in the first embodiment, and the brightness of the image projected on the projection area can be reduced. Can be suppressed.

  In the second embodiment, as described above, a laser including a region of relaxation oscillation in one frame image for each frame of an image (video) composed of a plurality of pixels based on a preset arrangement pattern. By changing the position of the pixel from which the laser beam that does not include the light and relaxation vibration regions is output, the position of the pixel from which the laser light that includes the relaxation vibration region and the laser light that does not include the relaxation vibration region is output. By setting the arrangement pattern in advance so that it can be moved evenly over the entire image, it is possible to suppress the generation of speckle noise evenly over the entire image, thus reducing the generation of speckle noise more effectively over the entire image. be able to.

  In the second embodiment, as described above, when the ratio of pixels to which laser light including a region of relaxation oscillation per frame in the arrangement pattern is 1/3, the frame period is one frame. By configuring the frame to be three times the number of frames (3 frames), it is performed once for all pixels (1/3 ×) within a frame period consisting of three frames (3 frames) three times as many as one frame. Since 3 = 1) is a calculation in which a pixel to which a laser beam including a region of relaxation oscillation is output is assigned, generation of speckle noise can be reduced at all pixel positions.

  In the second embodiment, as described above, the memory 115b that stores the arrangement pattern of the pixels that output the laser light including the relaxation vibration region and the pixels that output the laser light not including the relaxation vibration region is provided. By providing, the relaxation oscillation can be easily performed based on the arrangement pattern of the pixel that outputs the laser beam including the relaxation oscillation region stored in the memory 115b and the pixel that outputs the laser beam that does not include the relaxation oscillation region. The positions of the pixels that output the laser light including the region and the pixels that output the laser light not including the relaxation oscillation region can be arranged in a predetermined arrangement pattern.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. 10 and 11. In the portable projector according to the third embodiment, an arrangement pattern of pixels that output a laser beam including a relaxation oscillation region and a pixel that outputs a laser beam that does not include a relaxation oscillation region for an entire frame of an image. Unlike the second embodiment to be generated, an arrangement pattern corresponding to the number of pixels obtained by dividing one frame into a plurality of pixels is generated, and an arrangement pattern corresponding to the number of pixels obtained by dividing one frame into a plurality of pieces is connected to thereby generate one frame. An example of generating an arrangement pattern of pixels that output laser light including a region of relaxation oscillation and pixels that output laser light not including a region of relaxation vibration will be described.

  In the third embodiment, as shown in FIG. 10, the laser control unit 215 includes an arrangement pattern generation circuit 215a and arrangement patterns (A, B, and C patterns (see FIG. 11)) generated by the arrangement pattern generation circuit 215a. And a pattern selection circuit 215c for selecting an arrangement pattern from the memory 215b. The laser control unit 215 includes a laser beam including a preset relaxation vibration region (including a region driven to reduce speckle noise) and does not include a relaxation vibration region (only a normal drive region). Based on the arrangement pattern of pixels that output laser light, laser light that includes a preset relaxation vibration region and laser light that does not include a relaxation vibration region are output for each frame of an image. The pixel position is changed. The memory 215b is an example of the “storage unit” in the present invention.

  The arrangement pattern generation circuit 215a has a function of generating an arrangement pattern (see FIG. 11) of pixels that output laser light including a relaxation vibration region and laser light not including a relaxation vibration region. Further, as shown in FIG. 11, the arrangement pattern generation circuit 215a generates a pattern for outputting laser light including a relaxation oscillation region at a ratio of about 33% per 1/4 frame of one frame. It is configured. Then, the laser control unit 215 connects the four arrangement patterns (for example, the arrangement pattern A) generated in units of 1/4 frame, thereby outputting a laser beam including a region of relaxation vibration for one frame. And the arrangement pattern of the pixel from which the laser beam not including the region of relaxation oscillation is output is generated. As a result, the amount of patterns to be generated is reduced to ¼, so that the amount of memory used can be reduced.

  Further, the laser control unit 215 is configured to generate an arrangement pattern in which the laser beam including the relaxation oscillation region is set to generate an arrangement pattern that includes approximately 33% (1 / n = 1/3). In addition to an arrangement pattern in which four patterns A are connected, an arrangement pattern for 3 (n = 3) frames, an arrangement pattern in which four arrangement patterns B are connected, and an arrangement pattern in which four arrangement patterns C are connected Configured to generate. In this arrangement pattern, laser light including a region of relaxation oscillation is output once for all pixels during a frame period of three frames. The laser beam including the relaxation oscillation region is an example of the “first laser beam” in the present invention, and the laser beam not including the relaxation oscillation region is an example of the “second laser beam” in the present invention. . A pixel that outputs laser light including a region of relaxation vibration is an example of the “first image forming element” in the present invention, and a pixel that outputs laser light not including a region of relaxation vibration is “ It is an example of a “second image forming element”.

  In the third embodiment, the memory 215b has a function of storing the arrangement pattern generated by the arrangement pattern generation circuit 215a. Further, as shown in FIG. 11, the pattern selection circuit 215c has a function of selecting an arrangement pattern from the memory 215b in the order of A pattern, B pattern, and C pattern. Then, as shown in FIG. 10, the laser control unit 215 has an arrangement pattern in which four pieces of arrangement patterns (A pattern, B pattern, and C pattern) selected by the pattern selection circuit 215c are joined together. The laser drive current waveform based on the above is controlled to be output to the laser driver 16.

  In the third embodiment, as described above, a laser including a region of relaxation oscillation in which the output of laser light becomes unstable at the initial stage of laser oscillation with respect to some of the plurality of image forming elements (pixels). By performing the control to output light, the generation of speckle noise can be reduced with a simple configuration as in the first and second embodiments, and the brightness of the image projected on the projection area can be reduced. Can be suppressed.

  In the third embodiment, as described above, a pattern is generated that outputs laser light including a region of relaxation oscillation at a ratio of about 33% per ¼ frame of one frame, and ¼. An arrangement pattern of pixels that output laser light including a region of relaxation vibration for one frame and pixels that output laser light not including a region of relaxation vibration by connecting four arrangement patterns generated in units of frames Since the data amount of the pixel arrangement pattern to be generated can be reduced to ¼ the size of the case where the entire frame is generated, the memory usage can be reduced. .

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. 1, 2, and 12 to 14. In the portable projector according to the fourth embodiment, an arrangement pattern of pixels that output laser light including a region of relaxation vibration and pixels that output laser light that does not include a region of relaxation vibration is abbreviated for one frame of an image. Unlike the second embodiment, which is generated uniformly, the ratio of the pixels where the laser beam including the region of relaxation oscillation is output is arranged in the both end portions in the scanning direction rather than the central portion in the scanning direction of the image. An example of generating an arrangement pattern so as to be higher will be described.

  In the fourth embodiment, as illustrated in FIG. 12, the laser control unit 315 includes an arrangement pattern generation circuit 315a, a memory 315b that stores the arrangement pattern generated by the arrangement pattern generation circuit 315a, and an arrangement pattern from the memory 315b. And a pattern selection circuit 315c to be selected. The laser control unit 315 includes a laser beam including a preset relaxation vibration region (including a region driven to reduce speckle noise) and a relaxation vibration region (only a normal drive region). Based on the arrangement pattern of pixels that output laser light, laser light that includes a preset relaxation vibration region and laser light that does not include a relaxation vibration region are output for each frame of an image. The pixel position is changed. The memory 315b is an example of the “storage unit” in the present invention.

  In the fourth embodiment, as shown in FIG. 13, the scanner mirror 17 (see FIG. 2) is a video (image) composed of a plurality of pixels (image forming elements) while changing the scanning speed of the RGB laser light. Is configured to project. Specifically, the angular velocity at which the scanner mirror 17 is vibrated in the horizontal direction (X direction (see FIG. 1)) of the projection range 2 is the largest near the central portion A in the horizontal direction (X direction) of the projection range 2. At the same time, it is configured to be the smallest in the vicinity of both ends B in the horizontal direction (X direction) of the projection range 2. That is, when the scanner mirror 17 is vibrated in the horizontal direction (X direction (see FIG. 1)) of the projection range 2, the scanning speed in the vicinity A of the central portion in the horizontal direction (X direction) of the projection range 2 is the projection range. 2 is configured to be higher than the scanning speed in the vicinity of both ends B in the horizontal direction (X direction).

  Further, as shown in FIG. 12, the arrangement pattern generation circuit 315a generates an arrangement pattern (see FIG. 14) of pixels that output laser light including a relaxation vibration region and laser light not including a relaxation vibration region. It has the function to do. Further, as shown in FIG. 14, the arrangement pattern generation circuit 315a applies about 33% (1/3) of laser light including a region of relaxation oscillation to the central pixel obtained by dividing the frame into three in the scanning direction. It is configured to perform control to output at a rate. In addition, the arrangement pattern generation circuit 315a performs control to output laser light including a region of relaxation oscillation at a ratio of 50% (1/2) to the pixels at both ends obtained by dividing the frame into three in the scanning direction. It is configured. The laser beam including the relaxation oscillation region is an example of the “first laser beam” in the present invention, and the laser beam not including the relaxation oscillation region is an example of the “second laser beam” in the present invention. . A pixel that outputs laser light including a region of relaxation vibration is an example of the “first image forming element” in the present invention, and a pixel that outputs laser light not including a region of relaxation vibration is “ It is an example of a “second image forming element”.

  In the fourth embodiment, as described above, for some of the plurality of image forming elements (pixels), a laser including a region of relaxation oscillation in which the output of laser light becomes unstable at the initial stage of laser oscillation. By performing light output control, the generation of speckle noise can be reduced with a simple configuration as in the first to third embodiments, and the brightness of the image projected on the projection area is reduced. Can be suppressed.

  Further, in the fourth embodiment, as described above, the arrangement pattern of the pixels from which the laser beam including the relaxation oscillation region and the laser beam not including the relaxation oscillation region are output from the central side portion in the image scanning direction. Also, the two end portions in the scanning direction are configured such that the ratio of pixels where laser light including a region of relaxation oscillation is output is higher. Here, the amount of laser light output to both end portions in the scanning direction is smaller than the center side portion in the scanning direction because the scanning speed is lower in the both end portions in the scanning direction than in the center side portion in the scanning direction. Many. In this case, if the ratio of the pixels where the laser beam including the region of relaxation oscillation is output is increased at both end portions in the scanning direction, speckle noise is sufficient at both end portions in the scanning direction. Sufficient luminance can be ensured while reducing the occurrence of.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIGS. 2, 4, 5, 15, and 16. In the portable projector according to the fifth embodiment, when laser light including a region of relaxation oscillation is output, all of the red LD 12, blue LD 13 and green LD 14 have relaxation oscillation regions regardless of the color of the laser beam. Unlike the first embodiment in which laser light is output so as to be included, an example in which laser light including a region of relaxation oscillation is output corresponding to each color of the laser light will be described.

  In the fifth embodiment, the laser control unit 415 includes a speckle noise reduction pixel selection circuit 415a and a laser drive current generation circuit 415b as shown in FIG. The speckle noise reduction pixel selection circuit 415a has a function of performing selection to output either laser light including a relaxation vibration region or laser light not including a relaxation vibration region to a predetermined pixel in an image. Have. Further, as shown in FIG. 16, the speckle noise reduction pixel selection circuit 415a performs control to output laser light including a relaxation oscillation region for each of the red LD 12, the blue LD 13, and the green LD 14 corresponding to the video data. It is configured as follows.

  The ratio of output of laser light including the relaxation oscillation region is as follows: green LD14 where speckle noise is most likely to occur, red LD12 where speckle noise is most likely to occur, and blue where speckle noise is most unlikely to occur. It is higher in order of LD13. That is, in the fifth embodiment, the laser light including the relaxation oscillation region of the green LD 14 is configured to be output in the range of 50% to 100%. Further, the laser beam including the relaxation oscillation region of the red LD 12 is configured to be output in a range of 30% to 80%. Further, the laser light including the region of relaxation oscillation of the blue LD 13 is configured to be output in a range of 0% to 50%.

  In the fifth embodiment, when laser light including a relaxation oscillation region is output, the green LD 14, the red LD 12, and the blue LD 13 each output laser light that does not include a relaxation oscillation region. Output to increase. Specifically, the area S1 surrounded by the output current and time in FIG. 4 (shaded portion in FIG. 4) is the same as the area S2 surrounded by the output current and time in FIG. 5 (shaded portion in FIG. 5). The current for outputting the laser light including the region of relaxation oscillation is adjusted so as to increase the area. As a result, a sufficient amount of light can be secured even when laser light including a region of relaxation oscillation is output, compared to when laser light not including a region of relaxation vibration is output.

  In the fifth embodiment, as described above, for some of the plurality of image forming elements (pixels), a laser including a region of relaxation oscillation in which the output of laser light becomes unstable at the initial stage of laser oscillation. By performing control to output light, the generation of speckle noise can be reduced with a simple configuration as in the first to fourth embodiments, and the brightness of the image projected on the projection area is reduced. Can be suppressed.

  In the fifth embodiment, as described above, the laser control unit 415 performs control to increase the ratio of the pixels corresponding to the laser light including the relaxation oscillation region in the order of the blue LD 13, the red LD 12, and the green LD 14. By configuring as described above, in the blue LD 13 in which speckle noise is less likely to occur, the ratio of the pixels that output laser light including the region of relaxation oscillation is reduced, while in the green LD 14 in which speckle noise is likely to occur, Since the ratio of pixels that output laser light including the region of relaxation oscillation can be increased, the generation of speckle noise can be effectively reduced according to the color of the laser.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to fifth embodiments, the example in which the present invention is applied to the portable projector as an example of the display device of the present invention has been described, but the present invention is not limited to this. The present invention can be applied to a display device such as a stationary laser projector as long as it is a display device that outputs laser light.

  In the first to fifth embodiments, the example in which the pixel position is changed for each frame has been described. However, the present invention is not limited to this. In the present invention, for example, the pixel position may be changed for each of a plurality of frames.

  In the first to fourth embodiments, an example in which the ratio of pixels that output laser light including a region of relaxation oscillation is set to about 33% (1/3) has been described. Not limited. If the ratio of the pixels that output the laser beam including the relaxation oscillation region is greater than 0% and less than 100%, the ratio of the pixels that output the laser beam including the relaxation oscillation region is any ratio. It may be set.

  In the second to fourth embodiments, the ratio of pixels that output laser light including the relaxation oscillation region is set to about 33% (1/3) and three types of patterns are generated. Although shown, the present invention is not limited to this. If n types of patterns are generated when the ratio of pixels that output laser light including the region of relaxation oscillation is 1 / n, n may be a value other than n = 3.

  In the third embodiment, the example in which the arrangement pattern is generated for ¼ frame of one frame is shown, but the present invention is not limited to this. If an arrangement pattern is generated by dividing one frame, the arrangement pattern need not be generated in units of 1/4 frame.

  In the fifth embodiment, an example in which one frame is divided into three in the scanning direction and the ratio of pixels that output laser light including a region of relaxation oscillation is changed for each divided region is shown. Is not limited to this. One frame may be divided into four or more divisions in the scanning direction, and the ratio of pixels to which laser light including a region of relaxation oscillation is output may be different for each divided region.

  In the first to fifth embodiments, an example is shown in which a scanner mirror, which is a small vibrating mirror element that can vibrate, is used as the projection unit. However, the present invention is not limited to this. Any member other than the mirror element may be used as long as it can scan the laser beam.

  In the first to fifth embodiments, the example in which the RGB laser light is projected onto the projection region 2 by using the red LD 12, the blue LD 13, and the green LD 14 as the laser light generator has been described. However, the laser light generator may be configured to generate RGB laser light from one LD (laser diode). In addition, the laser light generation unit may be configured to generate only single color laser light, or may be configured to generate laser light of two colors or four colors or more.

  In the first to fifth embodiments, an example in which RGB laser light is output by providing one red LD 12, one blue LD 13, and one green LD 14 is shown, but the present invention is not limited to this. In the present invention, RGB laser light may be output by providing a plurality of LDs of at least one of a red LD, a blue LD, and a green LD. For example, laser light may be output as RGGB laser light by providing only two green LDs.

  In the first to fifth embodiments, by driving one scanner mirror 17 around the X axis and the Y axis, the laser light is driven around the X axis and the Y axis by only one scanner mirror 17. However, the present invention is not limited to this example. In the present invention, the Y-axis drive mirror that scans the laser light in the X direction by driving around the Y-axis and the X-axis drive mirror that scans the laser light in the Y-direction by driving around the X-axis. By providing a mirror, the laser beam may be scanned in the X direction and the Y direction.

  In the first to fifth embodiments, the example in which the video input from the personal computer via the video input interface is projected onto the projection area has been described. However, the present invention is not limited to this. For example, the video data stored in the memory card is input via the card slot and the input video is projected onto the projection area. For example, the video is input and input by a method other than the signal input from the external device. You may make it project an image | video on a projection area | region.

12 Red LD (Laser beam generator, Red laser beam generator)
13 Blue LD (laser light generator, blue laser light generator)
14 Green LD (Laser beam generator, Green laser beam generator)
15, 115, 215, 315, 415 Laser control unit (control unit)
16 Laser driver (control unit)
17 Scanner mirror (projection unit)
100 Portable projector (display device)
115b, 215b, 315b Memory (storage unit)

Claims (6)

A laser beam generator for outputting a laser beam;
A projection unit that projects an image including a plurality of image forming elements on an arbitrary projection region by scanning the laser beam;
A first laser beam including a relaxation oscillation region in which an output of the laser beam becomes unstable at an initial stage of laser oscillation with respect to a predetermined position image forming element arranged at a predetermined position among the plurality of image forming elements; And a control unit that performs control to output the second laser beam that does not include the relaxation oscillation region while switching the second laser beam for each predetermined number of frames of the image including the plurality of image forming elements.   The control unit is configured to perform control to output the first laser light and the second laser light to the predetermined position image forming element while switching at random for each predetermined number of frames. The display device according to claim 1.   The control unit outputs the first laser beam and the second laser beam while switching the predetermined position image forming element based on a predetermined arrangement pattern set in advance for each predetermined number of frames. The display device according to claim 1, wherein the display device is configured to perform control.   The predetermined arrangement pattern is configured such that the first laser light is output to each of the plurality of image forming elements at least once during a frame period composed of a number of frames that is a multiple of the predetermined number of frames. The display device according to claim 3.   The display device according to claim 3, further comprising a storage unit that stores the predetermined arrangement pattern.   The display device according to claim 1, wherein the predetermined number of frames is one.

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