KR20070100015A - Image display system - Google Patents

Abstract

An image display system is provided to compensate distortion phenomenon of an image using a lens array and change paths of laser beams through the lens array, thereby simultaneously compensating distortion phenomenon of a horizontal direction and a vertical direction and obtaining short projecting length. An image display system comprises the followings: an image processing unit(10) for receiving an image signal from a predetermined input terminal, processing the received signal, and outputting the result as a control signal; an image generating unit(12) for outputting RGB laser beam for implementing an associated image; MEMS(Micro Electro Mechanical System)(14) scanning mirror for reflecting laser beams inputted from the image generating unit and projecting the laser beams on a screen; and a lens array for adjusting path lengths of the laser beams for changing the path lengths of the laser beams projected on the screen.

Description

Image Display System

1 is a schematic block diagram of an image display system for scanning an image using a MEMS scanning mirror.

FIG. 2 is a diagram illustrating a distortion phenomenon of an image generated by the image display system shown in FIG. 1.

3 is a view showing an image in which the distortion phenomenon of the image is partially corrected by the prior art.

4 is a diagram illustrating distortion of an image using a lens array according to an exemplary embodiment of the present invention.

5 is a diagram illustrating a process of correcting distortion of an image by the lens array illustrated in FIG. 4.

6 is a view showing that a laser beam incident on a MEMS scanning mirror is reflected.

7 is a view showing a method of calculating a distance between a lens array and a MEMS scanning mirror.

<Description of the symbols for the main parts of the drawings>

10: image signal processor 12: image generator

14: MEMS scanning mirror 16: screen

18: lens array

The present invention relates to a display system, and more particularly, to an image display system capable of correcting distortion of an image signal generated when an image is scanned using a display system including a micro scanning mirror.

Recently, as one of the next generation image display systems, an image display system using a laser as a light source and a MEMS (Micro Electro Mechanical System) scanning mirror (Mirror) for scanning an image has been developed. Such a display system uses a 1-dimension MEMS scanning mirror and a galvanometer or a 2-dimension MEMS scanning mirror to scan a laser beam to form a two-dimensional screen.

FIG. 1 is a schematic block diagram of an image display system for scanning an image using such a MEMS scanning mirror. As illustrated, the image display system includes an image signal processor 10, an image generator 12, and a MEMS scanning mirror. 14), and the image output from this image display system is projected on the screen (16).

The image signal processor 10 processes a video signal input through an input terminal (not shown), and outputs the processed result to the image generator 12 as a control signal. In this case, the image generating unit 12 outputs an RGB laser beam for implementing the corresponding image to the MEMS scanning mirror 14 corresponding to the control signal input from the image signal processing unit 10, and the output laser beam is the MEMS scanning. Reflected through the mirror 14 and scanned on the screen 16.

Since the MEMS scanning mirror 14 shown in FIG. 1 needs to be driven using the resonance mode, the MEMS scanning mirror 14 is simply mechanically reciprocated during the scanning operation. As a result, when the image is scanned at the edge of the screen 16 as shown in FIG. The velocity of 0 becomes zero and has a maximum speed when scanning an image in the center, thereby changing the scanning speed. Due to this phenomenon, when an image signal as shown in FIG. 2A is input, the input image is not projected and a distorted image as shown in FIG. 2B is projected. As shown in FIG. 2B, the image is distorted due to the difference in scanning speed between the edge and the center in the horizontal direction, and the image is distorted due to the difference in scanning speed between the edge and the center in the vertical direction.

In order to solve this problem, conventionally, when scanning in the horizontal direction, the edge portion is cut out through signal processing, and the speed difference in the area except the edge is slow in the slow portion, and the high speed portion is used to scan the edge portion. A method of correcting image distortion by short scanning has been proposed. In this method, the image distortion phenomenon in the horizontal direction can be corrected, but the image distortion phenomenon in the vertical direction cannot be corrected. That is, as shown in FIG. 3, the image distortion in the horizontal direction can be corrected through the signal processing, but in the vertical direction, the correction is impossible, so that the center portion has a large space between lines and the edge portion has a tight space between lines. Will be.

In addition, the method of correcting the distortion of the image through such a signal processing has a problem that not only requires fast signal processing but also increases the amount of memory required because the signal must be processed in real time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and to provide an image display system including a lens system capable of adjusting a path length of a laser beam output from an image generator in order to efficiently solve an image distortion phenomenon. It is a technical problem.

According to an aspect of the present invention, there is provided an image display system including: an image signal processor configured to receive an image signal from a predetermined input terminal, process a signal, and output the result as a control signal; An image generator for outputting RGB laser beams for implementing a corresponding image in response to a control signal input from the image signal processor; A MEMS scanning mirror reflecting the laser beams input from the image generating unit and scanning the laser beams on a screen; And a lens array positioned between the MEMS scanning mirror and the screen to adjust the path length of the laser beams so that the path lengths of the laser beams reflected by the MEMS scanning mirror and scanned onto the screen are different. It includes.

In this case, the lens array refracts the laser beam in the case of a laser beam scanned at a slow speed on the screen so that its path length becomes longer, and in the case of the laser beam scanned at a higher speed on the screen, does not refract the laser beam. It is characterized in that the path is shortened.

In one embodiment, the lens array is implemented by a plurality of lenses having different curvatures to adjust the path length of the laser beams incident on each lens, or the plurality of lens arrays are made of different materials and have different refractive indices. By implementing with two lenses, the path length of the laser beams incident on the respective lenses can be adjusted.

In a preferred embodiment, the lens array is arranged spaced apart from the MEMS scanning mirror by a predetermined distance or more in order to prevent overlapping of image data projected on the screen, wherein the predetermined interval is (diameter of laser beam / 2). / tan {(scan angle of MEMS scanning mirror / number of pixels on the screen) / 2}.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the embodiments described below, the same components as those included in the prior art will be described using the same reference numerals as those given to the components of the prior art.

4 illustrates image distortion of the lens array according to the exemplary embodiment of the present invention. As shown in FIG. 4A, when the image as shown in FIG. 4A is incident on the lens array 18 of the present invention, the image is distorted as shown in FIG. 4B. Specifically, the lens array 18 of the present invention is used in both the horizontal and vertical directions of the image. The distorted input image is distorted so that the edge portion is wider and the central portion is narrower.

This is because, as described above, when a predetermined image is incident on the MEMS scanning mirror 14, the edge portion of the image in both the horizontal and vertical directions due to the difference in scanning speed due to the mechanical reciprocating motion of the MEMS scanning mirror 14. Since the intervals are narrow and the center portion of the image is output widely, the edges in the horizontal and vertical directions are wider than the input images distorted in both the horizontal and vertical directions through the MEMS scanning mirror 14. The central part solves the distortion phenomenon of the image by distorting again using the lens array 18 capable of outputting the image so that the interval is narrowed.

A process of correcting the distortion of an image by the lens array illustrated in FIG. 4 will be described in more detail with reference to FIG. 5. As shown in FIG. 5A, in the case of an image display system in which the lens array 18 is not used, the image projected on the screen 16 is horizontal due to the difference in scanning speed caused by the MEMS scanning mirror 14. And it can be seen that the edges are narrow in all directions in the vertical direction, and the intervals are wider in the center.

However, in the case of the image display system including the lens array 18 according to the exemplary embodiment of the present invention, as shown in FIG. 5B, the scanning speed of the MEMS scanning mirror 14 is slow, so that the interval of the image is narrow. In the case of the edge, the path of the laser beam to be scanned is refracted so that the path has a longer length than the path of the laser beam to be scanned into the center portion where the interval of the image is wide due to the high scanning speed. As a result, the distortion of the image is corrected, and thus the image is projected to be uniform in both the horizontal and vertical directions.

The lens array 18 as described above is preferably formed of a plurality of lenses having different curvatures in order to adjust the path length of the incident laser beam. That is, the lens array is implemented by a plurality of lenses having different shapes. Accordingly, the degree of refraction of the incident laser beam is changed so that the path length of the laser beam can be adjusted. Meanwhile, in the modified embodiment, the lens array 18 may be formed of a plurality of lenses having the same shape but different materials and having different refractive indices.

In the above-described embodiment, as the path of the laser beam is changed by the lens array 18, a phenomenon in which images projected on each pixel on the screen 16 may overlap. Therefore, the lens array 18 is preferably spaced apart from the MEMS scanning mirror 14 by a predetermined interval in order to prevent the overlapping of the images. This will be described in detail with reference to FIGS. 6 and 7.

First, referring to FIG. 6, in which a laser beam incident on the MEMS scanning mirror 14 is reflected, the MEMS scanning mirror 14 reflects the laser beam incident at a predetermined diameter according to a preset scanning angle to display a screen ( 16). At this time, if the lens array 18 is not disposed spaced apart by a predetermined distance L from the MEMS scanning mirror 14, the phenomenon that the image to be projected on the N th pixel and the N + 1 th pixel overlaps with each other. Since it occurs, the lens array 18 should be spaced apart by more than L, which is a predetermined interval.

A method of calculating the distance between the lens array 18 and the MEMS scanning mirror 14 described above is illustrated in FIG. 7. For convenience of explanation, in the present embodiment, the diameter D of the incident laser beam is 0.5 mm, the scanning angle of the MEMS scanning mirror 14 is 60 °, and the screen 16 is 800 pixels. It shall be. Since the laser beam is scanned at an angle of 60 ° to the screen 16 composed of 800 pixels, the angle of the laser beam incident between adjacent pixels becomes 0.075 °, whereby the angle of part (a) in FIG. 7 is also 0.075 °. do. Therefore, the distance L between the MEMS scanning mirror 14 and the lens array 18 for preventing the overlapping of images between adjacent pixels is calculated by the following equation.

If D = 0.5mm in Equation 1 as described above, L becomes 38.2mm. Therefore, in the above-described embodiment, the lens array 18 should be disposed to be spaced apart from the MEMS scanning mirror 14 by at least 38.2mm. Overlapping of the image between pixels can be prevented. Generalizing the above-described equation is as follows.

That is, the distance between the lens array 18 and the MEMS scanning mirror 14 is calculated by the diameter of the laser beam, the scanning angle of the MEMS scanning mirror 14, and the number of pixels of the screen 16.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

As described above, according to the present invention, since the distortion of the image is corrected by using the lens array, not only the horizontal distortion but also the vertical distortion can be simultaneously corrected.

In addition, according to the present invention, since the path of the laser beam is changed through the lens array, the scanning angle of the MEMS scanning mirror is increased, thereby ensuring a short projection distance.

Claims (6)

A video signal processing unit which receives a video signal from a predetermined input terminal and processes the signal and outputs the result as a control signal; An image generator for outputting RGB laser beams for implementing a corresponding image in response to a control signal input from the image signal processor; A MEMS scanning mirror reflecting the laser beams input from the image generating unit and scanning the laser beams on a screen; And A lens array positioned between the MEMS scanning mirror and the screen to adjust path lengths of the laser beams so that path lengths of the laser beams reflected by the MEMS scanning mirror and scanned onto the screen are respectively different; Image display system comprising a. 2. The lens array of claim 1, wherein the lens array refracts the laser beam in the case of a laser beam scanned at a slow speed on the screen so that its path length is increased, and in the case of the laser beam scanned at a high speed on the screen. A video display system, characterized in that the path is shortened without refraction. The image display system of claim 1, wherein the path length of the laser beams incident to the respective lenses is adjusted by implementing the lens array as a plurality of lenses having different curvatures. The image display system of claim 1, wherein the lens array is made of a plurality of lenses having different refractive indices made of different materials to adjust path lengths of laser beams incident to each lens. The image display system of claim 1, wherein the lens array is spaced apart from the MEMS scanning mirror by a predetermined distance or more to prevent overlapping of the laser beams projected on the screen. The image display system according to claim 5, wherein the interval is calculated by a formula of (diameter of laser beam / 2) / tan {(scan angle of MEMS scanning mirror / number of pixels of screen) / 2}. .

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