Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1998-08-07
2001-09-25
Nguyen, Phu K. (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06295065
ABSTRACT:
FIELD OF INVENTION
The present invention relates to stereoscopic video display systems and in particular to a method and apparatus to alternate stereoscopic images in a video display device.
BACKGROUND OF THE INVENTION
Stereoscopic or three-dimensional vision may be produced on a two-dimensional medium by creating a pair of stereoscopic images; a left eye image and a right eye image. If a viewer sees only the left eye image with the left eye and the right eye image with the right eye, the viewer perceives a three-dimensional image from the two stereoscopic images.
Conventional video display devices such as computer monitors produce an image by rapidly creating a plurality of horizontal display lines stacked in a vertical frame. Once the horizontal display lines reaches the bottom of the vertical frame, the image is refreshed by recommencing the horizontal display lines from the top.
Currently, it is known to produce stereoscopic vision on a display device using a technique whereby the left eye image is held in one memory buffer and the right eye image is held in another memory buffer. The right and left eye images are rapidly alternated on the display device while liquid crystal display or LCD glasses, synchronized to the alternating pattern, restrict the viewers eyes to only seeing the corresponding right or left image as it is presented on the display device.
However, such stereoscopic systems suffer from certain disadvantages. Current stereoscopic systems are restricted by processor speed as to how fast it can synchronize the LCD glasses and alternate the left and right eye images on the display device. Such systems require more video display card memory, to contain right and left eye images, than is available on standard video display cards. Current standards for video display cards contain 1,000,000 bytes of memory while stereoscopic systems require 1,843,200 bytes of memory to display 640×480 full resolution color images. This restricts stereoscopic systems to low resolution images.
Current stereoscopic systems are also restricted by a video display card's speed as to how fast it can transfer the left and right eye images to the video display device.
Current stereoscopic systems are dependent on the type of host's video display card memory capacity, the speed at which the video display card can alternate images and the speed at which the processor can control the stereoscopic system, thus restricting the use of stereoscopic vision to specific hardware configurations.
Therefore, there is a need in the art for an improved stereoscopic display system which overcomes the disadvantages of the prior art.
SUMMARY OF THE INVENTION
In general terms, in one aspect of the present invention, there is provided an apparatus to create a stereoscopic display on a display device. The apparatus connects between a video card and a video display and operates by causing the display to rapidly alternate left eye and right eye stereoscopic images with every vertical refresh cycle. The apparatus cancels every other horizontal display line during a first vertical refresh cycle and then cancels the other horizontal display lines during the next vertical refresh cycle. The apparatus is used in synchronized combination with LCD glasses worn by the user which blocks the view in the left eye and the right eye alternately. The image generated by the video card and manipulated by the apparatus is a composite image, comprising a mixture of two stereoscopic images wherein one image is defined by the odd numbered horizontal display lines (every other horizontal display line commencing with the first such line) and the other is defined by the even numbered horizontal display lines (every other horizontal display line commencing with the second such line). The generation of such a composite image from two stereoscopic images is well-known in the art.
The apparatus comprises a switching circuit for use with a computer system generating a periodic vertical retrace signal, wherein each vertical retrace signal coincides with the start of a vertical refresh cycle comprising a plurality of horizontal display lines, a periodic horizontal retrace signal, wherein each horizontal retrace signal coincides with the start of a horizontal line, and at least one color signal, said switching circuit comprising:
a) means to detect the vertical retrace signal;
b) means to detect the horizontal retrace signal;
c) means connected to the horizontal retrace signal detection means for generating a squarewave signal having a period twice the period of the horizontal retrace signal; and
d) means for generating a blanking pulse which cancels the at least one color signal; and
e) means for synchronizing the blanking pulse with the squarewave signal such that every odd-numbered horizontal display line is blanked during a first image state and every even-numbered horizontal display line is blanked during a second image state;
f) wherein said synchronization means is connected to the vertical retrace detection means, the horizontal retrace signal detection means, the squarewave generation means and the blanking pulse generation means; and
g) means connected to the vertical retrace signal detection means and the synchronization means for switching between the first and second image states between successive vertical refresh cycles;
In its preferred embodiment, the switching circuit is combined with a voltage regulation circuit and a operating mode selection circuit. The combined circuitry is mounted to a circuit board which interconnects between a video card and a display device and has a manually operable power switch and a manually operable mode selection switch.
In general terns and in another aspect of the invention, there is provided a method of displaying a stereoscopic display on a display device. The method comprises the steps of:
a) providing a computer system which causes a display screen to display an image comprising a plurality of horizontal display lines, wherein a set of horizontal display lines is completed in a vertical refresh cycle;
b) providing a composite image represented by a plurality of horizontal display lines comprising first and second stereoscopic images wherein the first stereoscopic image is represented by the odd numbered horizontal lines (every other horizontal line commencing with the first such line) and the second stereoscopic image is represented by the even numbered horizontal lines (every other horizontal line commencing with the second such line);
c) providing an apparatus which cancels the second image during a first vertical refresh cycle and which cancels the first image during a second vertical refresh cycle; and
d) rapidly switching between the first and second vertical refresh cycles.
REFERENCES:
patent: 5821989 (1998-10-01), Lazzaro et al.
patent: 6011581 (2000-01-01), Swift et al.
patent: 6023276 (2000-02-01), Kawai et al.
patent: 6031564 (2000-02-01), Ma et al.
Bennett Jones LLP
Nguyen Phu K.
Tetratel Systems Limited
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