Television – Image signal processing circuitry specific to television – Switching
Reexamination Certificate
2001-07-11
2004-06-01
Kostak, Victor R. (Department: 2614)
Television
Image signal processing circuitry specific to television
Switching
C386S349000
Reexamination Certificate
active
06744475
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to video switching apparatus for switching between a plurality of video signal inputs and outputting the selected video signal input to video recording apparatus or a monitor, and in particular to video switching apparatus for processing the video signal input of a plurality of channels multiplexed in time units such as frames and fields.
2. Description of the Related Art
Video switching apparatus called a frame switcher or a multiplexer has been in use for inputting a plurality of video signals such as video outputs from a plurality of video cameras and dividing per channel the signal in time units such as frames and fields to multiplex the signals and outputting the signals to video recording apparatus such as a VTR, or inputting a multiple video signal generated by video recording apparatus and outputting the signal per channel onto a monitor. Such video switching apparatus generally appends an ID signal for identification to the video signal on each channel for multiplexing and records these video signals as a single video signal on video recording apparatus. To generate a multiplexed video signal, the ID signal superimposed on a video signal is read, the target video signal is selected based on the ID information and the video signals on the established channels are extracted so that only the video signals where the same ID signal is superimposed are output to a monitor. By appending an ID signal, it is possible to select and output a video signal on a predetermined channel.
Specifications of such an ID signal are uniquely defined per manufacturer and type of apparatus. While a multiple video signal on which an ID signal conforming to the apparatus in use is superimposed can be selected and generated, a multiple video signal on which an ID signal of an unsupported system is superimposed does not allow generation of the signal on a predetermined channel or video switchover since corresponding ID information cannot be recognized.
In order to solve such a problem, apparatus has been proposed for appending an ID signal conforming to the same system as the apparatus in use in generating a multiple video signal recorded with an ID signal of a different system is superimposed in order to allow generation control such as signal switchover via the appended ID signal. A configuration example of video switching apparatus for appending a ID signal conforming to the apparatus in use in generating a multiple video signal conforming to a different system.
Video switching apparatus
51
is composed of an ID detecting circuit
52
, an ID information read circuit
53
, a play/recording control circuit
54
, a selector for selecting video signals
55
, an ID generation circuit
56
, and a selector for selecting ID signals
57
. To a generation input terminal
58
is connected the output terminal of video recording apparatus
62
. To a recording output terminal
59
is connected the input terminal of the video recording apparatus
62
. To a monitor output terminal
60
is connected a monitor
61
.
The video switching apparatus
51
in this example is configured so that the generation mode may be set in advance on the menu setup section (not shown) by the user to input a setup mode signal. The case where a multiple video signal on which an ID signal conforming to the same system as the apparatus in use is superimposed is generated is called Mode A, while the case where a multiple video signal on which an ID signal of a different system is superimposed is generated is called Mode B.
For Mode A, the input of the selector
57
is connected to the generation input terminal
58
. A video signal input from the generation input terminal
58
is input to the ID detecting circuit
52
and the ID information read circuit
53
via the selector
57
. The ID detecting circuit
52
detects presence/absence of an ID signal in a video signal and outputs a switching control signal to the selector
55
depending on the detection result. In case the ID signal is detected (the ID signal is superimposed), the selector
55
outputs an output video signal S
2
of the play/recording control circuit
54
to the monitor output terminal
60
. In case the ID signal is not detected (the ID signal is not superimposed), the selector
55
outputs a video signal S
1
input from the generation input terminal
58
to the monitor output terminal
60
. The output video signal S
2
of the play/recording control circuit
54
is also output to the recording output terminal
59
.
The ID information read circuit
53
reads the information in the ID signal and outputs the ID information to the play/recording control circuit
54
. The play/recording control circuit
54
processes the video signal based on the input ID information. For example, the play/recording control circuit
54
extracts and outputs only a video signal where the predetermined same ID information specified by the user is superimposed from a multiple video signal divided on channels per frame or field. In case no ID information is input, the play/recording control circuit
54
outputs a black image video signal.
For Mode B, the input of the selector
57
is connected to the ID generation circuit
56
. A conforming ID signal generated in the ID generation circuit
56
is input to the ID detecting circuit
52
and the ID information read circuit
53
via the selector
57
. The ID detecting circuit
52
detects the ID signal generated in the ID generation circuit
56
and outputs a switching control signal to the play/recording control circuit
54
. The play/recording control circuit
54
outputs a video signal on a channel corresponding to the ID information from the multiple video signal. The video signal S
2
is output to the monitor output terminal
60
via the selector
55
. In this way, by generating and appending an ID system conforming to the system of the apparatus in use in generating a multiple video signal where an ID signal conforming to a different ID signal is superimposed, it is possible to control switchover of multiplexed video signals on channels.
The video switching apparatus
51
configured as mentioned earlier always appends a conforming ID signal to the input video signal S
1
for generation in Mode B, so that the ID information in the appended ID signal is input to the play/recording control circuit
54
even when the video recording apparatus
62
has stopped generation. Thus, the channel corresponding to the ID information in the video signal S
1
input from the generation input terminal
58
is output as a video signal S
21
from the play/recording control circuit
54
and input to the video recording apparatus
62
from the recording output terminal
59
.
The video recording apparatus
62
outputs (performs through output of) a signal input to the input terminal while it is not generating a video signal. When a video signal (actually noise component only) is input to the input terminal from the video switching apparatus
51
while generation by the video recording apparatus
62
is halted, the input video signal is output from the output terminal then input to the generation input terminal
58
of the video switching apparatus
51
. That is, when generation operation is halted in the video recording apparatus
62
while the video switching apparatus
51
is operating in Mode B, a so-called signal path loop is formed thus causing failure such as oscillation.
SUMMARY OF THE INVENTION
The invention has been proposed in view of the aforementioned circumstances and aims at providing video switching apparatus that can generate a multiple video signal where an ID signal conforming to a system different from that employed by the apparatus in use is superimposed, and that can prevent failure such as oscillation in the generation mode according to the different system.
In order to solve such a problem, the first aspect of the invention is video switching apparatus for performing switchover to generate a video switching apparatus multiplexed on a plurality of channels,
Ishimura Tsuneaki
Nozaki Kazuo
Kostak Victor R.
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
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