KR101660725B1 - laser display system - Google Patents

Abstract

The present invention relates to a laser display system capable of reducing the speckle phenomenon of laser light, and more particularly, to a laser display system capable of reducing the speckle phenomenon of laser light, and a laser display system for separating P- P and P polarized light and S polarized light on the screen to obtain S or P polarized light reaching the N-1th pixel implementation time and P or P polarized light reaching the Nth pixel implementation time at the Nth pixel position of one screen, And an optical scanner for superposing S-polarized light.

 Speckle, polarized light separator, interval, polarized light, optical path, reflective surface

Description

A laser display system

The present invention relates to a laser display system, and more particularly to a laser display system capable of reducing the speckle phenomenon of laser light.

In general, in addition to a rapid transition to a multimedia society, a large display screen and a high image quality are required, and in recent years, the implementation of a natural color in addition to a high resolution has become important.

In order to realize a perfect natural color, it is necessary to use a light source with high color purity such as a laser. One of systems for implementing an image using a laser is a display system using a light scanner.

[0002] A display system such as a laser projector and a laser projection system displays an image by projecting an input image signal on a screen using a laser light emitted from a laser light source. The display system mainly includes a presentation room, , Home theater (home theater) and so on.

The display system using a general optical scanner may include a laser light source, an optical modulator, an optical system, a light scanner, an image controller, and the like.

Here, the laser light source includes a red laser for generating red light, a green laser for generating green light, and a blue laser for generating blue light.

The laser light source emits the generated laser light to the optical modulator. The optical modulator modulates the incident laser light according to the image control signal of the image controller to generate the diffracted light and emits it to the optical system.

The generated diffracted light is transmitted to the optical scanner through the optical system. The optical scanner scans the light while the mirrors rotate at a predetermined angle according to the mirror control signal of the image control unit, and displays the image.

It is an object of the present invention to provide a laser display system capable of reducing the speckle phenomenon of laser light by using a polarization splitting unit that splits the incident laser light into P-polarized light and S-polarized light having a path difference.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. .

A laser display system according to the present invention includes: a laser illumination system for irradiating a laser beam; a polarization separation unit for separating P-polarized light and S-polarized light from laser light and reflecting the light with different optical paths at different times; S-polarized light is scanned on the screen to superpose an S or P polarized light reaching the (N-1) th pixel implementation time and a P or S polarized light reaching the Nth pixel implementation time at the Nth pixel position of one screen, And the like.

Here, the polarized light separating section may include a first prism having a first reflecting surface that reflects P or S polarized light from the laser light and transmits S or P polarized light, and a second prism that is disposed to face the first reflecting surface at a predetermined interval And a second prism having a second reflecting surface reflecting the S or P polarized light transmitted through the first reflecting surface.

At this time, it is preferable that the interval between the first reflection surface and the second reflection surface is the same on the whole surface, and the interval between the first reflection surface and the second reflection surface is a pixel pitch size of the screen.

Further, the interval between the first reflection surface and the second reflection surface may decrease or increase from the first side facing each other to the second lateral direction.

The refractive index between the first and second reflective surfaces may be the same as the refractive index of the first and second prisms.

Further, the P polarized light and the S polarized light reflected from the polarized light separating part can travel in the same direction through different optical paths.

Then, the optical scanner scans the screen for separated P-polarized light and S-polarized light so that only P or S polarized light reaches the first pixel position among the plurality of pixels constituting one screen, and S or P Only the polarization is reached, and the P and S polarizations can be superimposed on the pixel positions between the first and last pixels.

According to another aspect of the present invention, there is provided a liquid crystal display device including: a gap adjusting unit for adjusting an interval between a first prism and a second prism of a polarized light separating unit according to a predetermined control signal; and a controller for controlling the gap adjusting unit according to the size of a pixel pitch constituting a screen As shown in FIG.

Other objects, features and advantages of the present invention will become apparent from the detailed description of embodiments with reference to the accompanying drawings.

The laser display system according to the present invention has the following effects.

The present invention uses S or P polarized light reaching the (N-1) th pixel implementation time at the Nth pixel position of one screen by using a polarized light separation unit that separates the incident laser light into P polarized light and S polarized light having path differences By overlapping the P or S polarized light reaching the Nth pixel implementation time, the speckle phenomenon of the laser light can be reduced.

Therefore, the present invention can be suitably applied to a projector module embedded in a small portable device such as a digital camera, a cellular phone, and the like.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Generally, in a display using a laser, a display noise called a speckle is generated on the screen because of the coherence of the laser.

In order to solve this problem, polarization diversity, wavelength diversity, temporal averaging, and spatial averaging can be used.

In the present invention, a polarized light separator such as a PS prism is used to divide the polarized light spatially into two polarized lights, resulting in a path difference corresponding to the reflection point difference between the two surfaces.

At this time, two points of each polarized light are formed on the screen. When scanning is performed in the horizontal direction, S or P polarized light reaches at one point of the screen at time t1, and P or S polarized light reaches at time t2 , Overlap each other.

Therefore, the two lights having different polarizations form respective independent speckle patterns, and the two speckle patterns are equally distributed in the human eye, thereby achieving a speckle reducing effect, thereby realizing a smooth image.

The present invention will be described in more detail with reference to the drawings.

1 is a view showing a laser display system according to the present invention. As shown in FIG. 1, a laser illumination system 100 including a light source 11, a collimator 13, a color synthesis system 15, A polarized light separator 200, and a light scanner 300.

Here, the light source 11 is composed of a red laser light source 11a for generating red light, a green laser light source 11b for generating green light, and a blue laser light source 11c for generating blue light.

The red laser light source 11a is located in a region facing the first side of the color synthesizer 15 and the green laser light source 11b is located in a region facing the second side of the color synthesizer 15, The laser light source 11c may be located in a region facing the second side of the color synthesizer 15.

Next, the collimator 13 may be composed of first, second, and third collimators 13a, 13b, and 13c.

Here, the first collimator 13a is positioned between the red laser light source 11a and the first side of the color synthesizer 15 to make the red light parallel, and the second collimator 13b is disposed between the red laser light source 11a and the first side of the color synthesizer 15, And the third collimator 13c is disposed between the blue laser light source 11c and the second side of the color synthesizer 15 so as to be parallel to the second side of the color synthesizer 15, And is positioned between the side surfaces, thereby making blue light parallel.

That is, the first, second, and third collimators 13a, 13b, and 13c may have a minimum spot size on the screen by making the laser light close to parallel or substantially parallel .

Next, the color synthesizer 15 can perform a function of synthesizing red light, green light, and blue light on a single optical path and advancing it.

The polarized light separator 200 separates the P polarized light and the S polarized light from the incident laser light and reflects the P polarized light and the S polarized light to different optical paths at different times.

2A and 2B are views showing details of the polarization splitting unit of FIG. 1, wherein FIG. 2A is a polarization splitting unit according to the first embodiment of the present invention, and FIG. 2B is a polarization splitting unit according to the second embodiment of the present invention.

2A and 2B, the polarization separator 200 may be configured to include a first prism having a first reflecting surface 202 and a second prism having a second reflecting surface 204 have.

Here, the first reflecting surface 202 serves to reflect the P or S polarized light from the laser light and transmit the S or P polarized light, and the second reflecting surface 204 serves to reflect the P or S polarized light from the first reflecting surface 202 And may reflect the S or P polarized light transmitted through the first reflection surface 202. The first and second reflection surfaces 202 and 202 may be disposed to face each other with a predetermined gap therebetween.

As shown in Fig. 2A, in the polarized light separating portion of the first embodiment, the distance d between the first reflecting surface 202 and the second reflecting surface 204 may be the same for the entire opposing surfaces.

In this case, the distance d between the first reflection surface 202 and the second reflection surface 204 is preferably one pixel pitch on the screen.

This is because the P polarized light and the S polarized light separated by the polarized light separator 200 must arrive at two adjacent pixels instead of reaching the same pixel position on the screen as will be described later.

Therefore, the distance d between the first reflection surface 202 and the second reflection surface 204 can be varied according to the distance between the screen 400 and the optical scanner 300, Can be varied.

In the present invention, as a result of the test, it is preferable that the distance d between the first reflection surface and the second reflection surface is about 0.01 - 1 mm.

As described above, in the polarized light separating portion of the first embodiment of the present invention, since the distance d between the first reflecting surface 202 and the second reflecting surface 204 is the same for the entire surface, Of the first prism is equal to the angle 2 of the second prism having the second reflecting surface 204 as a side.

The space 206 between the first and second reflective surfaces 202 and 204 is preferably filled with a material having a refractive index equal to or substantially similar to that of the first and second prisms.

That is, the space 206 between the first and second reflective surfaces 202 and 204 preferably has a refractive index difference of about 0.1 or less with respect to the refractive indexes of the first and second prisms.

As described above, the P-polarized light and the S-polarized light reflected from the first and second reflective surfaces 202 and 204 of the polarization separator 200 travel in the same direction through different optical paths.

2B, the interval between the first reflection surface 202 and the second reflection surface 204 is set such that the distance from the first side to the second side Direction to increase or decrease.

That is, the distance d1 between the first reflecting surface 202 and the second reflecting surface 204 located on the first side of the polarized light separating unit 200 is equal to the distance d1 between the first reflecting surface 202 and the second reflecting surface 204, Can be made smaller than the distance d2 between the reflective surface 202 and the second reflective surface 204. [

As described above, the reason for manufacturing is that when the P polarized light and the S polarized light separated by the polarized light separator 200 reach the screen, they arrive at a narrower gap than one pixel, thereby further improving the speckle removal effect .

That is, when the separated P-polarized light and S-polarized light arrive at the screen, when the difference reaches one pixel or more, the P-polarized light and the S-polarized light arrive at the screen with an interval difference of one pixel or less More preferable.

Therefore, the P-polarized light and the S-polarized light reflected from the first and second reflecting surfaces 202 and 204 of the polarized light separating section 200 travel through the different optical paths but proceed in the same direction. Therefore, as shown in FIG. 2B, The distance d1 between the first reflecting surface 202 and the second reflecting surface 204 located on the first side of the polarized light separating section 200 is smaller than the distance d1 between the first reflecting surface 202 located on the second side of the polarization separating section 200 The light scanner 300 is positioned at the lower side in FIG. 2B, but the light scanner 300 is disposed at the lower side in FIG. 2B. However, in the case where the light scanner 300 is made smaller than the distance d2 between the first reflection surface 202 and the second reflection surface 204, The interval d1 between the first reflecting surface 202 and the second reflecting surface 204 is equal to the interval between the first reflecting surface 202 and the second reflecting surface 204 located on the second side of the polarization splitting section 200 d2, it is preferable that the optical scanner 300 is positioned on the upper side in Fig. 2B.

Therefore, in the polarized light separating section 200 of the second embodiment, since the distances d1 and d2 between the first reflecting surface 202 and the second reflecting surface 204 are different from each other in the entire surface, The angle? 1 of the first prism that forms the sides of the second prism 204 may be larger or smaller than the angle? 2 of the second prism having the second reflecting surface 204 as sides.

1, the optical scanner 300 scans the screen 400 with separated P-polarized light and S-polarized light so that the N-th pixel position of one screen reaches the (N-1) th pixel implementation time Overlapping the P or S polarized light reaching the Nth pixel implementation time.

Here, the optical scanner 300 scans the separated P-polarized light and S-polarized light to reach only the P or S polarized light at the first pixel position among the plurality of pixels constituting one screen, Only the S or P polarized light can be reached, and the pixel position between the first pixel and the last pixel can overlap the P polarized light and the S polarized light.

The operation of the laser display system according to the present invention will now be described.

First, as shown in FIG. 1, when the laser illumination system 100 irradiates a laser beam, the polarized light separator 200 separates the P polarized light and the S polarized light from the laser light and reflects the P polarized light and the S polarized light at different times, .

That is, as shown in FIG. 2A, the first reflection surface 202 of the polarization splitting unit 200 reflects P or S polarized light from the laser light, and transmits S or P polarized light.

The second reflection surface 204 of the polarization splitting unit 200 reflects the S or P polarized light transmitted through the first reflection surface 202.

They have different optical path differences and time differences by the distance d between the first reflecting surface 202 and the second reflecting surface 204. [

Then, the optical scanner 300 scans the screen for P-polarized light and S-polarized light separated from the polarized light separating unit 200 to obtain S or P (N-1) Overlapping the P or S polarized light reaching the polarization time and the Nth pixel implementation time.

3A to 3D are views for explaining a laser speckle removal method of the laser display system according to the present invention.

3A is a view showing the position of S polarized light reaching the screen at time t1 and the position of S polarized light at time t2, FIG. 3B is a view showing the position of P polarized light reaching the screen at time t2 and S polarized light at time t3, Fig. 3C is a view showing the position of S polarized light reaching the screen at time t3 and S polarized light at time t4, and 3d is a view showing the position of P polarized light reaching the screen at time t4 and S polarized light at time t5.

First, as shown in FIG. 3A, the optical scanner 300 scans light in a horizontal direction for one frame. First, at time t1, P polarized light is incident on the first pixel p1 of the screen of the screen 400 , And S polarized light reaches the second pixel (p2) at time t21.

Then, as shown in Fig. 3B, P polarized light reaches the second pixel p2 of the screen of the screen 400 at time t2, and S polarized light reaches the third pixel p3 at time t3.

That is, in the second pixel p2, the S polarized light of the image to be applied to the first pixel p1 and the P polarized light of the image to be applied to the second pixel p2 are overlapped with each other at the same time.

Then, as shown in Fig. 3C, P polarization reaches the third pixel p3 of the screen of the screen 400 at time t3, and S polarization reaches the fourth pixel p4 at time t4.

That is, in the third pixel p3, the S polarized light of the image to be applied to the second pixel p2 and the P polarized light of the image to be applied to the third pixel p3 are overlapped with each other at the same time.

Next, as shown in FIG. 3D, P polarized light reaches the fourth pixel p4 of the screen of the screen 400 at time t4, and S polarized light reaches the fifth pixel p5 at time t5.

That is, in the fourth pixel p4, the S polarized light of the image to be applied to the third pixel p3 and the P polarized light of the image to be applied to the fourth pixel p4 are overlapped with each other at the same time.

As such, the optical scanner 300 superimposes, at the Nth pixel position of one screen, the S or P polarized light reaching the (N-1) th pixel implementation time and the P or S polarized light reaching the Nth pixel implementation time, The speckle phenomenon can be eliminated.

That is, the images that arrive at the respective pixels are not shown in the human eye, but these images are viewed in time.

Therefore, as each film image of a disconnected film looks like a moving picture, each of the images becomes visible to the human eye.

Thus, in each pixel on the screen, different polarizations for the image and the next image are superimposed, and each of the other polarizations forms a speckle noise that is independent of each other, and the noise is superimposed on the eyes so as to appear smooth do.

In this way, the present invention can be manufactured so that the interval d between the first and second prisms of the polarized light separator can be mechanically adjusted.

That is, although not shown, a controller and an interval adjusting unit may be additionally provided.

Here, the interval adjusting unit may perform a function of adjusting the interval between the first prism and the second prism of the polarization separator according to the control signal of the control unit.

The interval adjusting unit may be manufactured by an actuator capable of fine driving.

The control unit controls the interval adjusting unit according to the size of the pixel pitch constituting one screen.

In addition, the present invention can be installed by further adding a distortion correcting element between the optical scanner and the screen.

Here, the distortion correcting element has at least two transmitting surfaces to correct the distortion of the light refracted from the light scanner.

The distortion correcting element corrects the distortion using the principle of compensating the light path difference, and two types of distortion correcting elements can be used.

The first type has a wedge shape in which two transmitting faces are not parallel to each other, the refractive index of the entire region is the same type, the second type has a shape in which two transmitting faces are parallel, It is a type whose refractive index changes in one direction.

That is, the first type is a type in which the first transmitting surface and the second transmitting surface are not parallel to each other, and the second type is a type in which the first transmitting surface and the second transmitting surface are parallel to each other.

Here, it is preferable that the distortion correcting element has first and second transmitting surfaces. The first transmitting surface means a surface through which light emitted to the outside from the optical scanner is transmitted, and the second transmitting surface has a first and a second transmitting surface, Means the side facing the transmissive surface.

Therefore, the first type of distortion correcting element has first and second transmitting surfaces, the first transmitting surface and the second transmitting surface are not parallel to each other, and the material therebetween is a transparent material having the same refractive index in all regions .

The first type of distortion correcting element may have a distance between the first transmitting surface and the second transmitting surface as the distance from the lower portion to the upper portion is closer to the lower portion, and the distance from the upper portion to the lower portion may be closer to the lower portion.

Therefore, when the incident light passes through the distortion correcting element from the light scanner, the light directed toward the central area of the screen is refracted through the thick part of the distortion correcting element, and the light directed to the edge of the screen is transmitted through the thin part of the distortion correcting element So that the optical path difference can be compensated.

That is, the refractive index of the first type of distortion correcting element is the same as that of the entire region, but the refractive index of light passing through the distortion correcting element due to the thickness difference differs from region to region.

The second type of distortion correcting element has first and second transmitting surfaces, the first transmitting surface and the second transmitting surface are parallel to each other, and the material therebetween is horizontal with respect to the first and second transmitting surfaces And the refractive index is changed in the direction.

That is, the refractive index of the second type of distortion correcting element may be increased from the lower end to the upper end, or the refractive index may be increased from the upper end to the lower end.

Therefore, when the incident light passes through the distortion correcting element from the light scanner, the light directed toward the central region of the screen is refracted by passing through the low-refractive index portion of the distortion correcting element region, It is possible to compensate for the optical path difference by transmitting and refracting a portion having a high refractive index.

In addition, the distortion correcting element of the present invention may be coated with an AR (anti-reflection) film so that light loss does not occur on the first and second transmitting surfaces.

The distortion correcting element may be made of transparent glass, transparent plastic or the like.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments but should be determined according to the claims.

1 is a view showing a laser display system according to the present invention;

2A and 2B are views showing details of the polarized light separator of FIG.

3A to 3D are diagrams for explaining a laser speckle removal method in a laser display system according to the present invention

Claims (13)

A laser illumination system for irradiating laser light; A polarized light separator for separating the P-polarized light and the S-polarized light from the laser light and reflecting the P-polarized light and the S-polarized light with different optical paths at different times; And, The separated P-polarized light and S-polarized light are scanned on the screen to obtain S or P polarized light reaching the N-1th pixel implementation time and P or S polarized light reaching the Nth pixel implementation time at the Nth pixel position of one screen, And a light scanner for superimposing the light beam on the light source, The polarized- A first prism having a first reflection surface that reflects P or S polarized light from the laser light and transmits S or P polarized light, And a second prism having a second reflecting surface disposed to face the first reflecting surfaces at predetermined intervals and to reflect S or P polarized light transmitted through the first reflecting surface, Wherein an interval between the first reflection surface and the second reflection surface is a distance Wherein the distance between the screen and the light scanner is variable depending on the distance between the screen and the light scanner. The laser illumination system according to claim 1, A light source that generates red light, green light, and blue light, And a color synthesizer for synthesizing the red light, the green light, and the blue light. The light source according to claim 2, A red laser light source positioned in a region facing the first side of the color synthesis system to generate the red light; A green laser light source positioned in a region facing the second side of the color synthesis system to generate the green light; And, And a blue laser light source positioned in a region facing the second side of the color synthesizer to generate the blue light. [3] The laser display system of claim 2, wherein a collimator is disposed between the light source and the color synthesis system to parallelize light generated from the light source. delete The laser display system according to claim 1, wherein an interval between the first reflecting surface and the second reflecting surface is the same on the front surface. The laser display system according to claim 1, wherein an interval between the first reflection surface and the second reflection surface is a pixel pitch size of the screen. 2. The laser display system according to claim 1, wherein an interval between the first reflective surface and the second reflective surface is 0.01 - 1 mm. 2. The laser display system according to claim 1, wherein an interval between the first reflecting surface and the second reflecting surface decreases or increases in a second lateral direction from a first side facing each other. The laser display system according to claim 1, wherein a refractive index between the first and second reflective surfaces is equal to a refractive index of the first and second prisms. The laser display system according to claim 1, wherein the P polarized light and the S polarized light reflected from the polarized light separating part travel in the same direction through different optical paths. The optical scanner according to claim 1, wherein the optical scanner scans the separated P-polarized light and S-polarized light to reach only the P or S polarized light at the first pixel position among the plurality of pixels constituting the screen, Th < / RTI > pixel position to the S-polarized light, and superposing P-polarized light and S-polarized light at the pixel position between the first and the last pixel. The method according to claim 1, An interval adjusting unit for adjusting an interval between the first prism and the second prism of the polarization splitting unit according to a predetermined control signal; Further comprising a controller for controlling the interval adjusting unit according to a size of a pixel pitch constituting the screen.

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