Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1998-09-14
2000-10-24
Shankar, Vijay
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
345 85, 359215, 359216, G09G 334
Patent
active
06137461&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
a) Field of the Invention
The invention is directed to a device for displaying a video image with a source emitting at least an intensity-modulated light bundle and to a deflecting device for deflecting the light bundle, as well as to the angle-proportional scanning of N.sub.p image points in lines over an angle .alpha..sub..rho., and to the angle-proportional scanning of the light bundle of N.sub.z lines of the video image over an angle .alpha..sub.z. The invention is further directed to a production process for a device of the kind mentioned above for which a source emitting at least an intensity-modulated light bundle and a deflecting device for angle-proportional scanning of N.sub.p image points in lines over an angle .alpha..sub..rho. and for angle-proportional scanning of N.sub.z lines of the video image over an angle .alpha..sub.z of the light bundle are provided. The invention is further directed to a method for displaying a video image in which at least one intensity-modulated light bundle is emitted from a source and is deflected by means of a deflecting device for angle-proportional scanning of N.sub.p image points in lines over an angle .alpha..sub..rho. and for angle-proportional scanning of N.sub.z lines of the picture over an angle .alpha..sub.z.
By "source" is meant hereinafter not only an individual light generator but also any combination of different light sources arranged in an optional manner.
b) Description of the Related Art
Devices of the type mentioned above are known, for example, from DE 43 24 848 C1. In devices of this kind, light bundles are deflected line-by-line in the direction of a screen corresponding to the electron beam in conventional television. A further deflection vertical to the line scanning serves to scan in the image direction.
During scanning, individual image points are illuminated on the screen, wherein the intensities of the light bundles are controlled with respect to the color and brightness of the respective illuminated image points. Three lasers of different wavelength whose intensity is suitably modulated are provided in the source for color display.
Problems arise in line deflection because it requires a very high frequency. Such deflections are commonly carried out by acoustooptical modulators or, according to DE 43 24 848 C1, with polygon mirrors. However, it is anticipated that the physical boundaries with respect to scan rates will soon be met in impending high-resolution television such as HDTV. Therefore, further developments are necessary in the field of polygon mirrors or acoustooptical modulators.
With a vertical scan rate (frame frequency or field frequency) of 50 Hz, for example, the following frequencies are required for line deflection:
______________________________________ PAL interlaced 15.625 Hz
PAL noninterlaced
31.250 Hz
HDTV interlaced 31.250 Hz
HDTV noninterlaced
62.500 Hz.
______________________________________
Horizontal scan rates of about 32 kHz are achieved by high-technology polygon mirror wheels. Typical specifications for these polygon mirror wheels are a rotational frequency of 1.250 Hz using 25 facets. Such polygon mirrors and other mechanical mirror deflection systems with similar parameters already practically represent an optimum with respect to attainable dynamics, deflection angle, diameter of the light bundle, freedom from dispersion, noise, construction dimensions, media supply, and costs.
However, the limitations in the dynamics of moving-mass mechanical deflection systems impose limitations on the suitability of these systems, outstanding per se, for applications in the area of high-quality laser projection technology, especially for laser shows or planetaria.
A doubling of the deflection frequency, e.g., by means of doubling the polygon facets, is impossible because of the resulting reduction in the length of the individual facets with the diameter remaining the same. On the other hand, an increase in diameter raises the requirements for the polygon mirror consi
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Deter Christhard
Frost Holger
Hiller Klaus
Vogel Wolfgang
LDT Gmb&H Co. Laser-Display-Technologie KG
Said Mansour M.
Shankar Vijay
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