KR101064860B1 - Laser display apparatus - Google Patents

Abstract

The present invention relates to a laser display device, wherein the laser display device according to the present invention includes a laser light source (21) (22) (23) for emitting a laser beam and a display element (51) for generating an image by irradiating the laser beam. 52, 53, a projection optical system 80 for magnifying and projecting the image generated by the display elements 51, 52, 53, and a screen on which an image projected by the projection optical system 80 is imaged. 90 and the display elements 51, 52, 53 to reciprocate to prevent the generation of a speckle pattern due to the interference of the laser beam on the screen 90, thereby reducing the periodic path difference of the laser beam. It characterized in that it comprises a device for moving device (61, 62, 63). According to this, since a periodic path difference is generated in the laser beam emitted to the screen 90, it is possible to effectively prevent the generation of the speckle pattern due to the interference of the laser beam.

Laser display devices, display elements, speckles, optical paths

Description

Laser display apparatus

1 is a view schematically showing a conventional projection display system.

2 is a configuration diagram schematically showing the configuration of a laser display device according to a preferred embodiment of the present invention.

3 and 4 are views showing a movement operation of the laser display device according to the preferred embodiment of the present invention shown in FIG.

FIG. 5 is a graph for explaining a movement operation of the laser display device illustrated in FIGS. 3 and 4.

6A and 6B are plan views schematically showing the configuration of a laser display device according to another embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

21,22,23; 1,2,3 Lasers 31,32,33; 1,2,3 Illumination Optical System

41,42,43; 1,2,3 TIR Prism 51,52,53; 1,2,3 DMD

61, 62, 63; 1,2,3 element shifting device 70; synthetic prism

80; projection optical system 90; screen

The present invention relates to a laser display device, and more particularly, to a laser display device that can improve the image quality of an image formed on a screen by suppressing the generation of speckle patterns due to interference of a laser beam.

In recent years, as the demand for high-quality large-screen display device increases, various methods and display devices for realizing a large screen have been developed.

Projection display system for enlarging and projecting a small screen in one way to implement a large screen is equipped with an optical engine for implementing a small screen.

The optical engine includes a display device such as a liquid crystal display (LCD), a digital micromirror device (DMD), a liquid crystal on silicon (LCoS), and a grate lighting valve (GLV). Among these display devices, LCDs have been mainly used to meet the trend of miniaturization and light weight, but recently, the development and release of projection display systems using DMDs, which are excellent for high contrast and fast in development, have been increasing.

1 is a view schematically showing a conventional projection display system.

As shown in FIG. 1, the projection display system includes a light source 11, an illumination optical system 12, a display element 13, and a projection optical system 14.

As the light source 11, a lamp or a laser that emits white light is used. In recent years, lasers, which have superior color, clarity, color gamut, and contrast, are mainly used as compared to lamps.

In the projection display system having such a configuration, the light emitted from the light source 11 is incident on the display element 13 via the illumination optical system 12. The display element 13 displays an image by adjusting the transmittance of the incident beam, and the generated image is enlarged and projected onto the screen 15 through the projection optical system 14.

By the way, in the case of the light source 11 using the laser, the sharpness and contrast of the color can be increased, the color reproducibility can be improved, and an image close to the natural color can be displayed, but is generated by the coherence inherent in the laser beam. There is a problem that the image quality is degraded due to the speckle.

That is, when an image is displayed through a laser beam having the same frequency and phase, interference of the laser beam occurs, causing a speckle in which small grains are sparkling on the screen 15 to deteriorate the image quality.

Moreover, the speckle pattern is observed to be larger as it is farther from the screen 15, and the speckle pattern becomes larger than the display resolution at a certain distance away from the screen 15, so that the image quality of the display is significantly reduced. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a laser display device which improves image quality by suppressing the occurrence of speckle fringes due to inherent interference of a laser beam.

A laser display device according to the present invention for achieving the above object is a laser light source for emitting a laser beam, a display element for generating an image by irradiating the laser beam, and a projection to enlarge and project the image generated by the display element A periodic path difference is generated in the laser beam by reciprocating the display element to prevent the generation of a speckle pattern due to interference of the laser beam and an optical system, a screen on which the image projected by the projection optical system is imaged. It characterized in that it comprises a device for moving the device.

Here, the moving distance of the display element may be an integer multiple of the unit pixel of the display element.

In addition, the time taken to move the display element once is preferably 10% or less of the movement period of the display element.

In addition, the element transfer device may use a piezoelectric vibration device or a solenoid vibration device.

On the other hand, the laser display device according to another embodiment of the present invention, a laser light source for emitting a laser beam, a display device for generating an image by irradiating the laser beam, and a projection to enlarge and project the image generated by the display device An optical system, a screen on which an image projected by the projection optical system is imaged, and a screen installed on the screen, and rotatably installed between the display element and the projection optical system to prevent a speckle pattern caused by interference of a laser beam. And an optical device for periodically changing an optical path of the laser beam from the display device to the projection optical system.

According to the present invention, it is possible to generate a periodic optical path difference of the laser beam that proceeds to the screen, it is possible to prevent the speckle pattern is generated by the interference of the laser beam.

Hereinafter, a laser display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 2 to 5.

2 is a configuration diagram schematically showing the configuration of a laser display device according to a preferred embodiment of the present invention, Figures 3 and 4 is a movement operation of the laser display device according to a preferred embodiment of the present invention shown in FIG. FIG. 5 is a graph for explaining a movement operation of the laser display device shown in FIGS. 3 and 4.

As shown in FIG. 2, the laser display device according to the preferred embodiment of the present invention includes the first, second, and third lasers 21, 22, 23, and the first, second, and third illumination optical systems 31. (32) (33), 1, 2, 3 TIR prism (41) (42) (43), three display elements (51) (52) (53), 1, 2, 3 element movement Apparatus 61, 62, 63, composite prism 70, projection optical system 80, and screen 90 are included.

The first, second and third lasers 21, 22 and 23 are laser light sources for generating a laser beam, the first laser 21 emits a red laser beam, and the second laser 22 is a green laser. The beam is emitted, and the third laser 23 emits a blue laser beam.

The first illumination optical system 31 is installed on the optical path of the red laser beam emitted from the first laser 21 to transmit the red laser beam, the second illumination optical system 32 is the second laser 22 Is installed on the optical path of the green laser beam emitted from the green laser beam to transmit the green laser beam, the third illumination optical system 33 is installed on the optical path of the blue laser beam emitted from the third laser 23 Blue laser beam Send it. These first to third illumination optical systems 31, 32 and 33 are composed of optical elements such as lenses and prisms.

The first, second, and third TIR prisms 41, 42, and 43 are formed by joining two prisms with a small air gap. Each of these TIR prisms 41, 42, 43 totally reflects each laser beam incident from the illumination optical system 31, 32, 33 onto each of the display elements 51, 52, 53, and each display. The image laser beam reflected from the elements 51, 52 and 53 is transmitted. The first TIR prism 41 is installed on the optical path of the red laser beam passing through the first illumination optical system 31, and the second TIR prism 42 is passed through the second illumination optical system 32. The third TIR prism 43 is installed on the optical path of the blue laser beam passing through the third illumination optical system 33. As shown in FIG. 2, a reflector 44 for changing the optical path of the laser beam is provided between the second TIR prism 42 and the second illumination optical system 32.

The three display elements 51, 52, and 53 generate images by receiving red, green, and blue laser beams emitted from each of the lasers 21, 22, and 23. In the present embodiment, a DMD is generated. (Digital Micromirror Device) will be described. However, the present invention is not limited to this configuration, and other devices such as liquid crystal display (LCD), liquid crystal on silicon (LCoS), and grate lighting valve (GLV) may be used as the display device.                     

As shown in FIG. 2, the first DMD 51 is disposed on the optical path in which the red laser beam is reflected by the first TIR prism 41. The image laser beam generated by the first DMD 51 passes through the first TIR prism 41 and proceeds to the composite prism 70. The second DMD 52 is disposed on the optical path in which the green laser beam is reflected by the second TIR prism 42. The imaging laser beam generated by the second DMD 52 passes through the second TIR prism 42 and proceeds to the composite prism 70. In addition, the third DMD 53 is disposed on the optical path of the blue laser beam reflected by the third TIR prism 43, and the image laser beam generated by the third DMD 53 is the third TIR prism 43. ) And proceeds to the synthetic prism (70).

The first, second, and third device moving devices 61, 62, and 63 are used to generate periodic path differences in the laser beam traveling toward the screen 90. Each DMD (51, 52, 53) ) To reciprocate at high speed. The DMDs 51, 52, and 53 generate movement distances of the first, second, and third element mobile devices 61, 62, 63 to move the corresponding DMDs 51, 52, 53. It is an integer multiple of one to several times the unit pixel Pixel, and the speed of reciprocating each DMD 51, 52, 53 is one to several times the frame rate at which the laser beam forms an image.

In the present embodiment shown in FIG. 3, the distance by which the first element transfer device 61 reciprocates the first DMD 51 is three times the unit pixel generated by the first DMD 51. At this time, the movement distance at which the second and third device moving devices 62 and 63 move the second and third DMDs 52 and 53 is also a distance of 3 pixels. Although not shown, these element transfer devices 61, 62, 63 are controlled by a control device that controls the overall operation of the laser display device.                     

Each of these device moving devices (61, 62, 63) can be implemented with various vibration devices that are currently developed. As is well known, piezoelectric vibrators can be used to reciprocate each DMD 51, 52, 53 at high speed, and a motor or solenoid vibrator can be used to perform the function.

The synthetic prism 70 is disposed on an optical path where the red, green, and blue laser beams passing through the first, second, and third TIR prisms 41, 42, 43 intersect. In the synthesizing prism 70, a color image in which three laser beams are synthesized is generated, and the generated image is transmitted to the projection optical system 80.

The projection optical system 80 enlarges and projects the image which has been advanced from the synthetic prism 70 onto the screen 90. Accordingly, a color image obtained by synthesizing the image generated by each DMD 51, 52, 53 is formed on the screen 90.

Hereinafter, with reference to the accompanying drawings will be described the operation of the laser display device according to a preferred embodiment of the present invention.

As shown in FIG. 2, the red, green, and blue laser beams generated by each of the lasers 21, 22, 23 pass through the first, second, and third illumination optical systems 31, 32, 33. The first, second, and third TIR prisms 41, 42, and 43 are incident. These laser beams incident on the respective TIR prisms 41, 42, 43 are totally reflected and incident on the first, second, and third DMDs 51, 52, 53, respectively.

At this time, each DMD (51) 52 (53) receives a video signal to generate a specific image, the first DMD (51) is irradiated with a red laser beam and the red image laser beam first TIR prism (41) To reflect. Similarly, the second DMD 52 reflects the green image laser beam to the second TIR prism 42, and the third DMD 53 reflects the blue image laser beam to the third TIR prism 43.

The first, second and third element transfer devices 61, 62 and 63 while the images are generated in the first, second, and third DMDs 51, 52, and 53 are as shown in FIG. The laser beam is irradiated to the DMDs 51, 52 and 53 to move each DMD 51, 52, 53 to the left or right at a rate of 1 to several times the frame rate at which the image is generated. Let's do it. When the DMDs 51, 52, and 53 are vibrated from side to side, the image formed on the screen 90 may be shaken from side to side. Therefore, the image signal transmitted to each DMD 51, 52, 53 is It is controlled in a certain way.

That is, as shown in FIG. 4, when the image of (a) is imaged on the screen 90, when each DMD 51, 52, 53 is moved to the left, each DMD (51) (52) The video signal is controlled to generate an image as shown in (b) at (53), and when each DMD (51) (52) (53) is moved to the right, each DMD (51) (52) (53) is connected to (c). Control the video signal such that the video is generated. As the DMDs 51, 52, and 53 are vibrated from side to side, the image signal is moved to change the image of each pixel of each of the DMDs 51, 52, 53, so that the screen 90 Image without jitter is formed.

In addition, since the images formed on the screen 90 are observed as noise when each of the DMDs 51, 52, 53 are moved left and right, the first, second, and third device moving devices ( The movement of 61, 62, 63 to move each DMD 51, 52, 53 is controlled as shown in FIG.                     

That is, the first, second, and third element mobile devices 61, 62, and 63 are fixed at the right (R) or the left (L) at the time when the DMDs 51, 52, and 53 are displayed. It is to keep the state stopped for a time, and to change the position of each DMD (51) 52 (53) to allow the DMD (51) (52) 53 to move at high speed. At this time, the time (t _m ) for the DMD 51, 52, 53 to move from the right (R) to the left (L) or the left (L) to the right (R) is each DMD (51) (52) (53) It is less than 10% of movement period (T).

In this manner, the red, green, and blue image lights generated by the first, second, and third DMDs 51, 52, and 53 may be used to respectively transmit the first, second, and third TIR prisms 41, 42, and 43, respectively. It is transmitted and synthesized in the synthetic prism 70. In addition, the color image generated in the synthetic prism 70 is projected to the screen 90 by the projection optical system 80.

Here, a periodic path difference is generated in each laser beam traveling to the screen 90 by vibrating the DMDs 51, 52, and 53 at the same or faster rate than the frame rate. Since the speckle pattern due to coherence of is moved with the DMD 51, 52, 53 at a faster rate than the frame rate, the speckle pattern is not visible on the screen 90.

6A and 6B are plan views illustrating a laser display device according to another exemplary embodiment of the present invention.

As shown in FIGS. 6A and 6B, the laser display device according to another embodiment of the present invention includes an optical element 75 rotatably installed between the display element 55 and the projection optical system 85. The optical element 75 refracts the laser beam at a specific angle according to the beam incidence angle, and changes the optical path of the laser beam within a predetermined range according to the rotation angle.

6A shows a state in which the right end of the image projected by the projection optical system 85 is located at the right critical position, and FIG. 6B shows the right end of the image projected by the optical element 75 in the projection optical system 85. The part is located in the right critical position. Therefore, the effective screen area P of the screen on which the image is actually imaged becomes a portion where the images commonly overlap at two critical positions.

As such, when the optical path of the laser beam is changed by the optical element 75, the image signal transmitted to the display element 55 is controlled according to the changed position of the laser beam so that the image is formed without shaking on the screen. . This video signal control method is the same as in the laser display apparatus according to the preferred embodiment.

In this way, by rotating the optical element 55 to change the optical path of the laser beam, it is possible to prevent the speckle pattern generated by the interference of the laser beam.

According to the present invention as described above, to move the display element so as to generate a periodic path difference to the laser beam emitted to the screen, or to install an optical element that can bend the laser beam between the display element and the projection optical system As a result, the generation of a speckle pattern due to interference of the laser beam can be effectively prevented.

The present invention has been shown and described with reference to preferred embodiments for illustrating the principles of the invention. However, the present invention is not limited to the configuration as shown and described as above, and various modifications and changes may be made without departing from the spirit and scope of the appended claims. Accordingly, all such modifications, changes and equivalents should be considered to be within the scope of the present invention.

Claims (6)

A laser light source for emitting a laser beam; A display device for generating an image by receiving the laser beam; A projection optical system configured to enlarge and project an image generated by the display element; A screen on which an image magnified and projected by the projection optical system is formed; And And a device moving device for generating a periodic path difference of the laser beam by reciprocating the display device to prevent the speckle pattern caused by the interference of the laser beam on the screen. The method of claim 1, And a moving distance of the display element is an integer multiple of a unit pixel of the display element. delete The method of claim 1, The device moving device is a laser display device, characterized in that using the piezoelectric vibration device. The method of claim 1, The device moving device is a laser display device, characterized in that using the solenoid vibration device. A laser light source for emitting a laser beam; A display device for generating an image by receiving the laser beam; A projection optical system configured to enlarge and project an image generated by the display element; A screen on which an image magnified and projected by the projection optical system is formed; And In order to prevent the generation of speckle fringes due to interference of the laser beam on the screen, the optical path of the laser beam from the display element to the projection optical system is periodically rotatably installed between the display element and the projection optical system. Laser display device comprising a; optical element for changing.

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