Computer graphics processing and selective visual display system – Plural display systems – Remotely located
Reexamination Certificate
1995-03-10
2003-04-15
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Plural display systems
Remotely located
C345S001100, C709S204000
Reexamination Certificate
active
06549178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication terminal apparatus for communication among multiple locations.
2. Related Background Art
Efficacy of communication terminals utilizing communication channels, such as television conference terminals, is attracting attention in recent years, from the standpoint of reduction of costs of business trips and of effective utilization of time. Also, there is being developed a multi-point television conference system with multi-point function for conducting a conference among multiple locations, in addition to point-to-point function for conducting a conference between two points.
In such multi-point television conference system, the communication among multiple locations is generally realized by a multi-point control unit (MCU), but there is recently developed a system capable of realizing the communication among multiple locations without the MCU, by connecting plural information channels to the different television conference terminals and connecting the information channels so as to form a loop or a bus.
In such television conference system, in the point-to-point mode, various display modes may be realized on each display unit such as (1) display of a received image over the entire image frame, (2) graphic display over the entire image frame, with a window display therein of the received image, or (3) combined display of the own image and the received image on graphic display, and such initial setting may also be suitably varied. Also in the multi-point mode, there can be increased the number of received images to be displayed, in addition to the display modes in case of the point-to-point mode.
FIG. 4
is a block diagram of such conventional multi-point television conference terminal, wherein a camera
1
, serving as the image input means of the terminal, is used for entering the image of the user of this terminal or a drawing. A display unit
2
, for displaying the input image data from the camera
1
or the image data received from another terminal, is composed for example of a CRT (cathode ray tube) or a LCD (liquid crystal display device). A video input interface unit
3
effects switching of the image input means (camera
1
), A/D (analog-to-digital) conversion of the image data, conversion of image data size, transformation of image data format, etc. under the control of a system control unit
11
to be explained later.
A video output interface unit
4
is composed of a received image scaling unit
4
a
for converting the image size of received image data, an image memory unit
4
b
for temporarily storing the image data at the image size conversion by the received image scaling unit
4
a,
an image memory control unit
4
c
for controlling the image data write-in into and image data read-out from the image memory unit
4
b,
and a TV signal encoding unit
4
d
for converting the image data, read from the image memory unit
4
b,
into television (TV) signals under the control of said image memory control unit
4
c.
A video encode/decode unit
5
, for encoding the transmission image signal and decoding the received image signal according to the recommendation H.261 of ITU-T (former CCITT: Consultation Committee for International Telegraph and Telephone), is composed of a video encoding unit
5
a
and a video decoding unit
5
b.
There are also provided a handset
6
serving as voice input/output means of the present terminal, a microphone/speaker
7
serving as another voice input/output means of the present terminal, and an voice input/output interface unit
8
for effecting echo cancellation in the use of the handset
6
or the microphone/speaker
7
, generation of various tones, such as dialling tone, calling tone, busy tone, call arrival tone, etc., and switching of the voice input/output means (handset
6
and microphone/speaker
7
) under the control of the system control unit
11
.
A voice encode/decode unit
9
, composed of a voice encoding unit
9
a
and a voice decoding unit
9
b,
effects encoding of the transmission voice signal and decoding of the received voice signal according to voice encoding/decoding algorithms such as 64 kbps PCMA-law, 64 kbps PCM&mgr;-law, 64 kbps/56 kbps/48 kbps SB-ADPCM, 32 kbps ADPCM, 16 kbps (for example, LD-CELP) or 8 kbps under the instruction by the system control unit
11
. An input unit
10
, for entering control information for the entire control of the present terminal, is composed of a keyboard, a touch panel, a mouse, etc.
A system control unit
11
is provided with a CPU (central processing unit), a ROM (read-only memory), a RAM (random access memory), an auxiliary memory device, etc. and serves to monitor the status of various units, to prepare a display image according to the state of control of the entire terminal and to effect the execution of the application program. A demultiplex/multiplexing unit
12
effects multiplexing the voice signal from the voice encoding unit
9
a,
the image signal from the video encoding unit
5
a
and the control signal from the system control unit
11
in the unit of each transmission frame according to the ITU-T recommendation H.261 and demultiplexing of each received frame into the constituting media for transmission to various units. There are also shown a line interface unit
13
for line control according to an ISDN user network interface, and a communication line
14
such as ISDN.
In the following there will be explained the function of the multi-point television conference terminal of the above-explained configuration.
Input image from the camera
1
is supplied through the video input interface unit
3
to the video encoding unit
5
a.
Also, input voice from the handset
6
or the microphone/speaker
7
is supplied through the voice input/output interface unit
8
to the voice encoding unit
9
a.
The input image encoded in the video encoding unit
5
a,
the input voice encoded in the voice encoding unit
9
a,
and a control signal from the system control unit
11
are multiplexed in the unit of each transmission frame by the demultiplex/multiplexing unit
12
, and are supplied through the line interface unit
13
to the communication line
14
.
A received frame from the communication line
14
is transmitted through the line interface unit
13
and separated in the demultiplex/multiplexing unit
12
into the image signal, voice signal and control signal, which are respectively supplied to the video decoding unit
5
b,
the voice decoding unit
9
b
and the system control unit
11
. The received image data, decoded in the video decoding unit
5
b,
are transmitted through the video output interface unit
4
and displayed on the display unit
2
. Also, the received voice, decoded in the voice decoding unit
9
b,
is transmitted through the voice input/output interface unit
8
and is released from the handset
6
or the microphone/speaker
7
.
The function of the video output interface unit
4
will be explained in further details. The received image data, decoded in the video decoding unit
5
b,
are stored in the image memory unit
4
b.
The received image data have a certain image size for each frame. The image size scaling is unnecessary if the image size is equal to that of the TV monitor of the display unit
2
, but the image sizes are usually different. In order to mutually match the image sizes, the received image data stored in the image memory unit
4
b
are read under the control of the image memory control unit
4
b
according to the method of image size conversion and are supplied to the received image scaling unit
4
a.
The received image scaling unit
4
a
effects conversion of the image size according to a predetermined method, and the converted image data are stored in the image memory unit
4
b
again under the control of the image memory control unit
4
c.
The image data, thus stored in the image memory unit
4
b,
has an image size equal to that of the TV monitor. The image data, stored in the image memory unit
4
b
with the display image size of the TV m
LandOfFree
Communication terminal apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Communication terminal apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Communication terminal apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3012556