Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1997-10-10
2001-12-25
Shankar, Vijay (Department: 2778)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S111000, C348S563000, C348S564000, C348S565000
Reexamination Certificate
active
06333731
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to processing a image signal of a TV, and in particular to an improved apparatus for simultaneously displaying TV and PC (personal computer) images on a TV display by dividing the TV and PC images.
2. Description of the Conventional Art
FIG. 1
is a circuit diagram of a TV system having a conventional double screen display function. As shown therein, the circuit includes a microcomputer
106
for outputting a first control signal cs and a second control signal dw in order to display a double screen according to a viewer's selection; an audio/video switch
101
for outputting a single signal among a main image signal Vim which passes through a main tuner and an intermediate frequency processing unit (not illustrated) in accordance with the first control signal cs, a sub image signal Vis which passes through a sub tuner and the intermediate frequency processing unit, and an external input signal Vex; a first comb filter
102
for separating the main image signal Vim which is outputted from the audio/video switch
101
into a main luminance signal Ym and a main chrominance signal Cm by using a subcarrier frequency f
sc
of 3.58 MHz and applying the two signals to the audio/video switch
101
; a second comb filter
103
for separating the sub image signal Vis or the external input signal Vex which is received from the audio/video switch
101
into a sub luminance signal Ys and a sub chrominance signal Cs and then outputting the two signals; a double screen control unit
104
for receiving the main luminance signal Ym and the main chrominance signal Cm which are received from the audio/video switch
101
and the sub luminance signal Ys and the sub chrominance signal Cs which are received from the second comb filter
103
, and for outputting a double screen luminance signal Ydw and a double screen chrominance signal Cdw; a double screen switch
105
for outputting the main luminance signal Ym and the main chrominance signal Cm which are received from the audio/video switch
101
in accordance with the second control signal dw of the microcomputer
106
or outputting the double screen luminance signal Ydw and the double screen chrominance signal Cdw which are received from the double screen control unit
104
; a video chroma signal processing unit
107
for converting the luminance signal Y and the chrominance signal C which are received from the double screen switch
105
to primary color signals R, G, B, and amplifying and outputting the primary color signals; and a RGB amplifier
108
for converting the amplified R, G, B signals to a magnitude which is needed for driving a picture tube
109
.
Here, the external input signal Vex is a signal which is inputted to an external input terminal (not illustrated) of the TV, such as a video image signal.
The operation of the conventional TV system will now be described in detail.
When the main image signal Vim which passed through the main screen tuner and the intermediate frequency processing unit (not illustrated), the sub image signal Vis which passes through the sub screen tuner and the intermediate frequency processing unit, and the external input signal Vex are inputted to the audio/video switch
101
, the audio/video switch
101
sends the main image signal Vim to the first comb filter
102
through a first output terminal Vout
1
.
On the other hand, a viewer who decides to watch a picture (an image) according to the sub image signal Vis or the external input signal Vex controls the microcomputer
106
, and the sub image signal Vis or the external input signal Vex is inputted to the second comb filter
103
through a second output terminal Vout
2
in accordance with a logical state of the first control signal cs, which is changed by to the control of the viewer. The first comb filter
102
separates the main image signal Vim into the main luminance signal Ym and the main chrominance signal Cm by using the subcarrier frequency f
sc
of 3.58 MHz, and the main luminance signal Ym and the main chrominance signal Cm pass through the audio/video switch
101
, and then are inputted to the double screen control unit
104
and double screen switch
105
.
The second comb filter
103
separates the sub image signal Vis or the external input signal Vex received from the second output terminal Vout
2
into the sub luminance signal Ys and the sub chrominance signal Cs and sends the two signals to the double screen control unit
104
.
The double screen control unit
104
converts each inputted signals Ym, Cm, Ys, and Cs into a digital signal, reads and writes each signal in a memory, and again converts the digital signal to an analog signal. The double screen control unit
104
generates the double screen luminance signal Ydw and double screen chrominance signal Cdw by having a different read and write timing of each memory, and sends the two signals to the double screen switch
105
, thereby performing a double window or PIP. Here an applied frequency band is approximately 2 MHz.
The viewer decides whether to watch a single or double screen and controls the microcomputer
106
, and accordingly a logical state of the second control signal dw of the microcomputer
106
is changed, and the double screen switch
105
selects each signal from the above signals Ym, Cm, Ydw, and Cdw in accordance with the logical state of the second control signal dw and outputs the selected signals to the video chroma signal process unit
107
. The inputted signals Y and C are converted to the primary color signals R, G, B by an inner matrix in the video chroma signal process unit
107
and amplified up to the magnitude for which the RGB amplifier
108
needs to drive the picture tube
109
, and applied to each RGB cathode of the picture tube
109
, whereby a single screen appears according to the main image signal, or a double screen appears according to the main and sub image signals, or the main image and external input signals.
Therefore, the viewer can watch the single or double screen by controlling the microcomputer
106
.
In addition, the viewer also can watch a double screen processed in a personal computer PC by using the conventional art as described above. In this case, when the viewer connects the output terminal for outputting a image signal of the PC to an external input terminal, the image signal processed in the PC is inputted to the audio/video switch
101
through the external input terminal. That is, the external input signal Vex of the audio/video switch
101
becomes a PC image signal.
Also, when the viewer controls the microcomputer
106
, the double screen switch
105
transits the double screen luminance signal Ydw and the double screen chrominance signal Cdw outputted from the double screen control unit
104
, thus the double screen according to the main image signal and the PC image signal can be displayed. Accordingly, the viewer is able to watch the TV and PC image simultaneously.
The frequency band of the TV image signal is approximately 2 to 3 MHz, and the frequency band of the PC image signal with a high resolution is approximately 20 MHz in a VGA mode. Namely, a horizontal frequency of the PC image signal is about 31.5 kHz, twice as much as a TV horizontal frequency, and if the number of horizontal dot is 640, the frequency band is 31.5 KHz*640, that is, about 20 MHz.
In order to display the PC image of a high resolution, a TV system should be able to process the frequency band of 20 MHz. However, in the conventional art, when the PC image signal is inputted to the audio/video switch
101
, the PC image signal passes through the double screen control unit
104
, here the frequency band of about 2 MHz is applied for the double screen control unit
104
, thus the resolution of the PC image is considerably dropped because it needs the frequency band about 20 MHz.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus for simultaneously displaying a TV image and PC image which has a higher resolution than
LG Electronics Inc.
Said Mansour M.
Shankar Vijay
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