Flexible phase shift compensation for automatic sizing and...

Details Flexible phase shift compensation for automatic sizing and... Flexible phase shift compensation for automatic sizing and...

1998-10-01

2001-07-24

Hsia, Sherrie (Department: 2614)

Television

Synchronization

Control of picture position

C348S806000, C348S747000

Reexamination Certificate

active

06266097

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to display systems. In particular, the invention relates to adjusting the size and position of an image on a display device.
2. Background Information
Display devices are often used to transmit information to a user. Display devices typically receive a video signal and convert the video signal into an image for a user to view. The video signal may be received from a variety of sources such as a microprocessor in a computer system, a video storage media such as a video cassette recorder or a television transmission. Examples of devices which are used as display devices or monitors include cathode ray tubes (CRT) devices, liquid crystal display (LCD) devices, and plasma devices.
One common display device is a cathode ray tube (CRT).
FIG. 1
illustrates a typical cross-section of a CRT
100
. In CRT
100
, an electron gun
104
shoots an electron beam
108
through a set of magnets
112
to a fluorescent screen
116
. When electrons within the electron beam
108
strike the fluorescent screen
116
, the energy of the electrons excites a phosphorous coating causing the fluorescent screen
116
to emit light
120
photons.
The set of magnets
112
direct where the electron beam
108
strikes the fluorescent screen
116
. Typically, the set of magnets
112
includes a top magnet
124
and a bottom magnet
128
as well as a first side magnet
132
and a second side magnet
136
. Top magnet
124
and bottom magnet
128
move electron beam
108
from the top
130
of the fluorescent surface
116
to the bottom
131
of the fluorescent surface while side magnets
132
,
136
move electron beam
108
in a horizontal direction
138
across fluorescent screen
116
. Each sweep of the electron beam
108
in a horizontal direction
138
forms a scan line
140
on fluorescent screen
116
. Once a scan line
140
has been formed, the vertical magnets including top magnet
124
and bottom magnet
128
apply slightly different magnetic fields to move the electron beam to a new starting position
141
and allow side magnets
132
,
136
to again sweep the electron beam across the surface of the fluorescent screen
116
to form an adjacent or subsequent scan line
142
. By rapidly moving the electron beam across the screen, a series of scan lines forms an image for display on fluorescent screen
116
.
Electronics
144
control the electro magnetic fields created by the set of magnets
112
. Electronics
144
also control the firing of electron gun
104
. The video electronics
144
typically does this by processing video signals arriving from a processor such as a microcomputer
148
. However, current electronics typically do not automatically process the video signal to precisely center an image and properly adjust the size of an image for a particular monitor. Current systems allow manual centering and sizing of an image using physical controls on the screen. Such manual control is awkward and inefficient.
Thus, a method of processing of automatically centering an image and properly setting the resolution of the screen is needed.
SUMMARY OF THE INVENTION
A system and method to compensate for time delays which occur during the propagation and processing of a horizontal sync signal and a video signal. A video processing circuit receives the horizontal sync signal and adds a first compensation component to the horizontal sync signal. The video processing circuit determines whether the received horizontal sync signal has a positive or negative polarity and adds a second compensation component when the polarity of the received horizontal sync signal is different from a predetermined polarity. The second compensation corrects for differences in delay times caused by the polarity difference.


REFERENCES:
patent: 4739403 (1988-04-01), Mark

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