Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1993-08-23
2001-08-14
Harvey, Minsun Oh (Department: 2747)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
Reexamination Certificate
active
06275219
ABSTRACT:
The invention concerns optical projection displays, and, specifically, such displays having an associated digitizer which detects the position of a hand-held pointer contacting the display.
BACKGROUND OF THE INVENTION
FIG. 1
is a schematic of a large-screen video display. Three cathode-ray tubes, CRT, generate identical images. One image is typically red, one is green, and one is blue. Each CRT has an associated lens system and collimator, LC, which captures the CRT's image and projects it to a dichroic mirror, DCM. The DCM combines the three images, and a fourth lens system L projects the combined image to a display screen D, via a mirror M.
The large number of components in such a projection system imposes high cost. Further, the optical elements require precise mechanical alignment, which is expensive to both achieve and maintain. Also, all of the optical elements must be protected from ambient dust, which requires either periodic cleaning or enclosure in a dust-free container. The container imposes added cost, together with the problem (perhaps minor) of dissipating the heat generated by now-enclosed CRTs.
An alternate projection system is shown in
FIG. 2. A
light source
3
produces light
6
which is collimated by a lens system
9
. The collimated light is projected through a liquid crystal display
12
, which acts as a shutter. The liquid crystal display can be of the monochrome- or color type. A heat shield
11
protects the LCD from the heat of the light source
3
.
FIG. 3
shows the shuttering operation. Some pixels
16
are dark, and eclipse the collimated light
6
. Other pixels
18
are bright, and transmit the collimated light
6
. In the example of
FIG. 3
, the letter “d” is generated on the display screen D. The collimated light is modulated pixel-by-pixel.
The alternate projection system contains fewer parts, compared with that of FIG.
1
. The present invention is yet a further improvement of this alternate system.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an improved large-screen display.
It is a further object of the invention to provide a projection-type display which can detect the location of a pointer which contacts the display.
SUMMARY OF THE INVENTION
In one form of the invention, a large-screen video display includes a transmissive liquid crystal shutter, which modulates light received from a light source, and projects the modulated light to a screen. The screen contains a digitizer which ascertains the x- and y-coordinates of a pointer located near the screen.
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“Everex Shows New Display Technology”,The Seybold Report on Publishing Systems; vol. 21, No. 20; p. 47.
Harvey Minsun Oh
NCR Corporation
Welte Gregory A.
LandOfFree
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