Television – Format conversion – Line doublers type
Reexamination Certificate
2000-05-31
2004-09-28
Lee, Michael H. (Department: 2614)
Television
Format conversion
Line doublers type
C348S443000, C348S458000
Reexamination Certificate
active
06798458
ABSTRACT:
TECHNICAL FIELD
The present invention relates to image signal converters converting each of component video signals of different scanning formats to be supplied to a display device such as a television receiver into signals of a common scanning format.
BACKGROUND ART
A schematic structure of a conventional image signal converter incorporated in a television receiver such as a high-definition TV is shown in
FIG. 8. A
conventional image signal converter ICc includes an input terminal
1
, a color-difference signal demodulator
2
, a selector
3
, a sync separator
4
, an RGB processor
5
, and a display
6
.
The input terminal
1
receives a first component video signal Scv
1
including a luminance signal Y, a color-difference signal PB and a color-difference signal PR outputted from an external video/audio data source, typically a digital television STB (Set-top Box) or DVD player. The input terminal
1
then supplies each of the luminance signal Y, the color-difference signal PB and the color-difference signal PR included in the first component video signal Scv
1
to the selector
3
.
The color-difference signal demodulator
2
generates a second component video signal Scv
2
composed of a luminance signal Y, a color-difference signal U (=B−Y), and a color-difference signal V (=R−Y) from a luminance signal Y and a chroma signal C obtained based on a composite video signal of any television standard system (in this example, the NTSC system). The luminance signal Y, the color-difference signal U and the color-difference signal V (R−Y) of the second component video signal are each supplied to the selector
3
. Note that the luminance signal Y and the chroma signal C to be supplied to the color-difference signal demodulator
2
are obtained from, for example, an NTSC composite video signal supplied by a Y/C separator (not shown) after Y/C separation or an output from the so-called S terminal of a video tape recorder.
The selector
3
selectively outputs either the first component video signal Scv
1
(Y, PB, PR) from the input terminal
1
or the second component video signal Scv
2
(Y, U, V) from the color-difference signal demodulator
2
. Note that this selection of the component video signal is made by the selector
3
based on a selecting signal Sw externally provided.
The sync separator
4
is implemented by a sync separator circuit, which separates and extracts a horizontal synchronization signal H-SYNC and a vertical synchronization signal V-SYNC from the luminance signal Y included in the first or second component video signal Scv
1
or Scv
2
supplied by the selector
3
.
The RGB processor
5
is implemented by an RGB demodulator circuit, which demodulates the first component video signal Scv
1
Y, PB, PR) or the second component video signal Scv
2
(Y, U, V) and outputs the original color signals of R, G, and B.
An image is displayed on the display
6
based on the each of the color signals R. G, and B received from the RGB processor
5
.
The operation of image signal conversion by the above image signal converter ICc is briefly described below. A user operates a remote controller (not shown) to supply the selector
3
with the selecting signal Sw for providing an instruction of selecting either the first or second component video signal Scv
1
or Scv
2
and outputting the selected component video signal to the RGB processor
5
.
When the external device such as a digital television STB and DVD player is connected to the input terminal
1
, the selector
3
outputs the first component video signal Scv
1
received from the input terminal
1
based on the selecting signal Sw. Otherwise, the selector
3
outputs the second component video signal Scv
2
received from the color-difference signal demodulator
2
based on the selecting signal Sw.
The first component video signal Scv
1
(Y, PB, PR) supplied to the input terminal
1
is outputted to the selector
3
without any processing. If supported by an NTSC interlaced scanning format of approximately 480 valid display scanning lines per frame (hereinafter referred to as “
480
i
format”), the first component video signal Scv
1
(Y, PB, PR) is supplied to the RGB processor
5
through the selector
3
. Note that the luminance signal Y included in the first component video signal Scv
1
is supplied also to the sync separator
4
.
On the other hand, when the video signal of the NTSC
480
i
format is supplied to the color-difference signal demodulator
2
in a state that its luminance signal Y and chroma signal C have already been separated, the color-difference demodulator
2
demodulates these incoming signals and then outputs the second component video signal Scv
2
composed of the luminance signal Y and the color-difference signals U and V. In this case, as described above, the selector
3
is switched in advance so as to output the second component video signal Scv
2
received from the color-difference signal demodulator
2
. The second component video signal Scv
2
is supplied through the selector
3
to the RGB processor
5
, and the luminance signal Y included therein is supplied to the sync separator
4
.
The sync separator
4
separates and extracts the horizontal synchronization signal H-SYNC and the vertical synchronization signal V-SYNC from the received luminance signal Y. These extracted synchronization signals H-SYNC and V-SYNC are supplied to a deflector (not shown) in the display
6
.
The RGB processor
5
demodulates the first component video signal Scv
1
(Y, PB, PR) or the second component video signal Scv
2
(Y, U, V) to obtain original color signals of R, G, and B. These demodulated color signals are supplied to the display
6
.
As such, when the first component video signal of the
480
i
format is supplied by the input terminal
1
, or when the luminance signal Y and the chroma signal C of the
480
i
format are supplied to the color-difference signal demodulator
2
, a color image can be displayed on the display
6
.
However, in the image signal converter ICc, if a video signal of a scanning format other than the
480
i
format is supplied to the input terminal
1
as the first component video signal Scv
1
(Y, PB, PR), it is impossible to correctly display a color image of the first component video signal Scv
1
supplied to the display
6
.
For example, in some cases, the first component video signal Scv
1
(Y, PB, PR) is supported by a progressive scanning format of approximately 480 valid display scanning lines per frame (hereinafter referred to as “
480
p
” format). Since being a non-interlaced scanning, the progressive scanning format is different from the
480
i
format in the number of valid display scanning lines per field. Therefore, the display
6
cannot display an image of the
480
p
first component video signal Scv
1
supplied to the RGB processor
5
based on the horizontal and vertical synchronization signals H-SYNC and V-SYNC extracted by the sync separator
4
.
As such, in the image signal converter ICc, the image of the first component video signal Scv
1
cannot be correctly displayed except when the input signal is compliant with the
480
i
format. Therefore, the scanning format of the first component video signal Scv
1
, which is an output from the external device connected to the input terminal
1
, is severely limited.
In the long run, in digital television STBs and DVD players, it is expected that component video signals Scv of a plurality of types of scanning formats such as the
480
i
and
480
p
formats will be supplied thereto by the same output terminal for providing users with video of various image qualities. The image signal converter ICc, however, cannot meet such expectations.
An object of the present invention is to provide an image signal converter that converts each scanning format of incoming component video signals Scv of a plurality of types of scanning methods from external devices such as digital television STBs and DVD players for correct image display are supplied thereto.
Further, another object of the present invention
Lee Michael H.
Tran Trang U.
Wenderoth , Lind & Ponack, L.L.P.
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