Television – Bandwidth reduction system
Reexamination Certificate
1995-06-05
2002-12-24
Kostak, Victor R. (Department: 2611)
Television
Bandwidth reduction system
C348S441000, C348S014120
Reexamination Certificate
active
06498625
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a dynamic image transmission apparatus capable of transmitting dynamic image signals from a plurality of dynamic image signal sources to a plurality of dynamic image output apparatuses and, for example, to a dynamic image transmission apparatus that can be used in a dynamic image network for a TV meeting.
The present invention also relates to an image transmission apparatus for transmitting a plurality of dynamic image information signals through a multi-channel transmission path.
Furthermore, the present invention relates to an image transmission apparatus for encoding one-dimensional data such as voice data or two-dimensional data such as image data, and outputting decoded data.
A dynamic image transmission apparatus of this type is arranged as shown in, e.g., FIG.
34
.
In
FIG. 34
, reference numerals
101
a
and
101
b
denote video cameras as dynamic image signal sources; and
102
a
to
102
d,
modulators each having a function of modulating a dynamic image signal output from the video camera
101
a
(
101
b
) or a video tape recorder (VTR)
103
a
(
103
b
) at a desired frequency, and outputting the modulated signal onto a coaxial cable
110
. Reference numerals
103
a
and
103
b
denote VTRs; and
105
a
to
105
c,
demodulators each having a function of selectively demodulating a desired one of a plurality of dynamic image signals modulated by the modulators
102
a
to
102
d,
and output onto the coaxial cable
110
. The modulators
102
a
to
102
d,
the coaxial cable
110
, and the demodulators
105
a
to
105
c
form a dynamic image signal transmission channel. In this case, a multi-channel transmission path is constituted since a plurality of modulators and demodulators are used.
Reference numerals
106
a
to
106
c
denote output devices such as displays, video printers, and the like. The output devices
106
a
to
106
c
output dynamic image signals demodulated by the demodulators
105
a
to
105
c.
The modulation frequencies used in the modulators
102
a
to
102
d
are controlled to utilize frequencies which are not used for transmission on the coaxial cable
110
at the beginning of transmission of dynamic image signals from the dynamic image signal sources.
As a second prior art, a dynamic image transmission apparatus comprises an arrangement shown in, e.g.,
FIG. 35
so as to synthesize dynamic images of a plurality of attendants, and to display synthesized dynamic images on each terminal.
More specifically, in
FIG. 35
, reference numerals
151
a
to
151
c
denote terminals A to C as motion picture signal sources;
155
a
and
155
b,
terminals D and E as dynamic image output devices; and
160
, a coaxial cable as a transmission path.
In the terminals A to C (
151
a
to
151
c
), reference numerals
152
a
to
152
c
denote image input devices A to C; and
153
a
to
153
c,
size converters A to C each having a function of converting a dynamic image of, e.g., the face of an attendant input at a corresponding one of the image input devices A to C (
152
a
to
152
c
) into a desired size, and a function of modulating the input dynamic image signal at a desired frequency, and outputting the modulated signal onto the coaxial cable
160
. The dynamic image signals which are converted into a desired size, and modulated by the size converters A to C (
153
a
to
153
c
) are output onto the coaxial cable
160
.
In the terminals D and E (
155
a
and
155
b
), reference numerals
156
a
and
156
b
denote image synthesizers D and E for demodulating the modulated dynamic image signals from the coaxial cable
160
, and synthesizing the three demodulated dynamic images from the terminals A to C (
151
a
to
151
c
); and
157
a
and
157
b,
image output devices D and E such as displays.
FIG. 36
shows an example of dynamic images synthesized by the image synthesizers D and E (
156
a
and
156
b
). More specifically, the image output devices D and E (
157
a
and
157
b
) display the synthesized dynamic images, as shown in FIG.
36
.
As a third prior art, an apparatus comprising an arrangement shown in, e.g.,
FIG. 37
, is known.
In
FIG. 37
, reference numerals
171
a
to
171
c
denote image input devices F to H each having a function of receiving a dynamic image signal of, e.g., the face of an attendant, modulating the dynamic image signal at a desired frequency, and outputting the modulated signal onto a coaxial cable
180
; and
172
a
and
172
b,
terminals F and G. The terminals F and G (
172
a
and
172
b
) respectively comprise size converters F and G (
173
a
and
173
b
) for demodulating the modulated dynamic image signals from the coaxial cable
180
, and converting the demodulated dynamic image signals into a desired size, synthesizers F and G (
174
a
and
174
b
) for synthesizing the dynamic image signals received from the image input devices and output from the size converters F and G (
173
a
and
173
b
), as shown in, e.g.,
FIG. 36
, and image output devices F and G (
175
a
and
175
b
) for outputting the dynamic images synthesized by the synthesizers F and G (
174
a
and
174
b
)
However, in the above-mentioned prior art arrangements and methods, since one channel having a predetermined transmission capacity is assigned to the transmission of one dynamic image, when an image having a small amount of information such a frame having a small number of high-frequency components of a dynamic image to be transmitted is transmitted, the transmission capacity of the transmission channel is partially wasted, resulting in poor utilization efficiency of the transmission path of the entire network.
In particular, in the second prior art apparatus, for example, when it is attempted at the terminal D
155
a
to display only an image A from the terminal A
151
a
in a large scale, the operation of the size converter A
153
a
of the terminal
151
a
must be switched. However, since the terminals D
155
a
and E
155
b
share the received dynamic image signals, the image A is also displayed in a large scale on the terminal E
155
b.
In this manner, in the second prior art, it is impossible to change the output image size according to a request from a reception-side terminal without influencing an output image on another reception terminal.
In the third prior art apparatus, since the size converters F and G (
173
a
and
173
b
) are arranged on the reception-side terminals F and G (
172
a
and
172
b
), each terminal can output an image in a desired scale without influencing an output image on another reception terminal. However, since a transmission-side terminal cannot detect the size of a dynamic image signal requested by the reception-side terminal, even when the reception-side terminal requests only a reduced image signal, the transmission-side terminal must output an image onto the transmission path without reducing the image, i.e., without compressing the transmission band. For this reason, the frequency band of the transmission path is wastefully used.
As a conventional transmission system for transmitting dynamic image information in multi-channels, for example, the following system is known. In this system, a multi-channel transmission path is constituted by using a coaxial cable, and a plurality of modulators and demodulators, and a plurality of dynamic image information signals are transmitted.
However, in a transmission system of this type, when all the transmission channels of the multi-channel transmission path are busy, a transmission request of newly generated dynamic image information must wait until one of the transmission channels is ready, resulting in poor response to a transmission request.
As a method of solving this problem, the rights of use of transmission channels are sequentially changed in a predetermined time unit, thereby realizing transmission of dynamic image information signals numbering more than the number of transmission channels of the multi-channel transmission path. In this case, every time the right of use of the transmission channel is lost, dynamic image in
Kikuchi Takayuki
Mashimo Hiroshi
Yamamoto Mitsuro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Kostak Victor R.
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