Optics: image projectors – Miscellaneous
Reexamination Certificate
2000-08-11
2003-07-22
Dowling, William (Department: 2851)
Optics: image projectors
Miscellaneous
C345S056000, C353S099000
Reexamination Certificate
active
06595647
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Technical Field of the Invention
The present invention relates to a micro-display device, and in particular to a micro-display device used in an electronic projection display and having a pixel structure with adjustable displacement in the horizontal direction and vertical direction.
(b) Description of the Prior Art
Micro-displays are used in electrical projection display, for instance front projectors, computer displays, and projection TVs. The main function of the micro-display is to produce images by the optical projection, and by means of the mirror surface of the pixels, reflection may be turned “ON” or “OFF”. The control method of reflection is divided into the direct reflective method and the penetration method. For instance, in the DMD directive reflective-type structure mode, the light is directly reflected, or in the LCOS structure mode of the penetration type, the light first penetrates liquid crystal layer, then reflected by mirror surface of the pixels. “ON” action of a pixel means the reflected light penetrates the liquid crystal layer with a polarization state that pass analyzer and project on screen. “OFF” action of a pixel means the reflected light penetrate the liquid crystal layer but with a different polarization state that is blocked by analyzer. And further, in combination with the projection light source, the color splitting/combination mechanism and lens module, the original image can be enlarged and be projected onto a screen.
Referring to
FIG. 6
, light projection in a conventional micro-display, wherein a light source A is projected onto three polarizers A
1
, A
2
, and A
3
so as to separate Red, Green and Blue colors which form the basic light source, and a dichroic C being used to combine three light sources is located at an appropriate position with the three polarizers A
1
, A
2
, and A
3
.
In addition, the red, green and blue light are respectively projected onto the micro-display devices B
1
, B
2
and B
3
. They are the projection control devices for displaying images.
FIG. 7
shows the light combination process of a conventional micro-display based projection system wherein after the three monochromic lights have been projected onto the micro-display B
1
, B
2
and B
3
, the mirror surfaces of the display B
1
, B
2
and B
2
are controlled to reflect images, and then reflections are guided to polarizers C
1
, C
2
and C
3
and the three red, green, and blue colors are combined at dichroic C. The images of red, green and blue after passing through the dichroic can be focused onto a screen forming a color image.
In
FIG. 7
, the light combination process of the conventional micro-display based projection system consists of three steps: assembly of optical components, adjusting of optical components and calibration on light path. Thus, the position of images on the micro-display and the positions of other optical components have to be adjusted such that the projection of red, green, blue can be superimposed correctly to form an image on the screen. However, positional errors often occur in the process of assembly. Due to fact that the number of pixels of the micro-display B
1
, B
2
and B
3
is designed based on the resolution of image projected, the number thereof is basically constant. For instance, the image resolution XGA is 1024×768 pixel, SXGA is 1280×1028 pixel, and UXGA is 1600×1200. In order to provide precise superimposition of images, the position of micro-displays B
1
, B
2
and B
2
must be adjusted or the optical lens module must be adjusted. The adjustment and calibration of the projected image on the display is rather laborious, in particular, the adjustment along the horizontal direction (X-axis) and vertical direction (Y-axis). The calibration cannot be easily achieved by an inexperienced operator and consequently slows down production speed.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a micro-display device wherein a plurality of additional pixels are added along the horizontal direction and vertical direction surrounding original pixels facilitating the positional adjustment of the projected images along the horizontal direction and vertical direction.
Yet another object of the present invention is to provide a micro-display device for the adjustment of images along the vertical direction and horizontal direction, wherein a simple software or electronic circuit signal can be used to control the adjustment such that the adjustment of image superimposition for the micro-display is time saving which is beneficial to the industries.
One aspect of the present invention is to provide a micro-display device comprising a control chip, a driving circuit and a plurality of metallic mirror pixels. The reflecting element, the driving circuit and the control chip are mounted in sequence from top to bottom and the driving circuit is controlled by display signals from control chip so as to drive the reflecting elements to control the “ON” and “OFF” of additional metallic mirror pixels along the horizontal (X-axis) and the vertical (Y-axis) direction such that the projected light from micro-displays R, G, and B during light combination can be accurately adjusted to a superimposed state.
Accordingly, the present invention provides a micro-display array, which comprises an array of pixel elements and a driving circuit. The array has a display region formed from a number of pixel elements less than the total number of pixel elements in the array. The extra pixel elements are used for positional adjustment of images in order to combine images from different sources. Each pixel element has an upper protective layer, a first electrode layer fixed to a lower surface of the upper protective layer, a liquid crystal layer sandwiched between the first electrode layer and a second electrode layer. The second electrode layer is mounted to a control chip. The driving circuit is communicated with the control chips of the pixel elements so that the driving circuit selectively controls reflectance of each of the pixel elements to form a desired image.
REFERENCES:
patent: 5092671 (1992-03-01), Van Os
patent: 5653522 (1997-08-01), Loucks
patent: 5971546 (1999-10-01), Park
Dowling William
Rosenberg , Klein & Lee
Taiwan Micro Display Corporation
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