JP2730452B2 - Video conference system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video conference system capable of holding a conference while watching a monitor screen. 2. Description of the Related Art A video conference system has been realized in which conference rooms at mutually separated locations can be connected by video and audio, and a conference can be held while watching a monitor screen. With such a video conference system, it is possible to hold a conference in an atmosphere as if all the people in different places are in the same conference room. That is, in a video conference system, a camera, a monitor, a microphone, and a speaker are installed in each conference room.
Both are connected by a bidirectional video line and audio line. A video signal and an audio signal are transmitted via the video line and the audio line. Since a video signal has a very wide band, it cannot be transmitted via a line as it is. Therefore, for example, the band is compressed and transmitted by a high-efficiency encoding process of transmitting an inter-frame difference. [0004] In a video conference, a plurality of cameras are generally used in order to capture images of many persons who attend the conference, and also to capture documents and the like in addition to the portraits. However, if the outputs of these cameras are all transmitted in parallel, the transmission band will increase. Therefore, several transmission systems have been proposed that can effectively transmit necessary information through one transmission line. [0005] One of them is a split screen system. The split screen system utilizes the special feature that the attendees of a conference are spread side by side. That is, FIG. 6 shows a configuration of a transmitting side of a conventional video conference system, and includes 51A, 51B, 51C and 52A.
A, 52B, and 52C are attendees of the conference. Attendees 51
A to 51C and 52A to 52C attend the conference side by side as shown in FIG. Attendant 51A by camera 53
51C are imaged, and attendees 52A-
52C is imaged. The output of the camera 53 is supplied to the split synthesizing unit 55 and also to the signal switching unit 56. The output of the camera 54 is supplied to a split synthesizing unit 55 and also to a signal switching unit 56. Camera 5
3, 54 and the split synthesizing unit 55
Controls the timing of the synchronization signal. The output of the signal switching unit 56 is supplied to the CODEC 58 and transmitted via the line 59. The CODEC 58 performs a high-efficiency encoding process. [0006] When performing the split synthesis, as shown in FIG. 7, output screen V ₁ of the camera 53 is 1/2 of the normal screen high, output screen V ₂ of the camera 54 is in the normal screen height It is set to 1/2. And these screen heights are 1/2
And the current screen are stacked two-stage split synthesis unit 55, a split synthesis window V ₃ is formed. The screen V ₃ thus split and combined is displayed in the split combining section 55.
From the CODEC 58 via the signal switching unit 56
And transmitted via line 59. By performing the split combining in this manner, the camera outputs of the two cameras 53 and 54 can be transmitted through one transmission path. When split combining is not performed, the outputs of the cameras 53 and 54 are supplied to the CODEC 58 via the signal switching unit 56 and transmitted via the line 59. Transmit split composite screen or use camera 53 and 5
The signal switching unit 56 selects whether to transmit the output of No. 4 as it is. FIG. 8 shows the configuration of the receiving side of the video conference system. In FIG. 8, the image data transmitted via the line 59 is decoded by the CODEC 60. CO
The output of the DEC 60 is supplied to the split separation unit 61 and also to the signal switching units 62 and 63. Also,
The synchronization signal being output from the CODEC 60 is output to the synchronization separation circuit 64.
, And the separated synchronization signal is supplied to the synchronization control unit 65. When the split synthesized picture V ₃ is transmitted via the line 59, the split separating section 6
The screens stacked in two stages at 1 are separated into two. The separated screen outputs are supplied to displays 66 and 67 via signal switching units 62 and 63, respectively. This allows
As shown in FIG. 8, the images of the attendees 51A to 51C and 52A to 52C are displayed side by side on the displays 66 and 67. If the screen transmitted via the line 59 is not a screen synthesized by splitting, the output of the CODEC 60 is output to the display 6 via the signal switching units 62 and 63.
6 and 67. As a method of transmitting a plurality of camera outputs through one transmission line, there is a still image simultaneous display method. The still image simultaneous display method is for simultaneously displaying a still image such as a document in synchronization with the display of a moving image. That is, in FIG. 9, reference numeral 71 denotes a moving image camera for capturing the attendees of the conference, etc .;
Reference numeral 2 denotes a still image camera that captures a document or the like. The output of the video camera 71 and the output of the still image camera 72 are supplied to a signal switching and ID code insertion unit 73. When displaying the output of the still image camera 72, the signal switching and ID code inserting unit 73 temporarily suspends the output of the moving image camera 71, during which the output of the still image camera 72 is supplied to the CODEC 74 and the output signal is output. Is an ID signal indicating that the output is a still image output. The output of CODEC 74 is line 75
Is supplied to the CODEC 76 on the receiving side via the
The output of C76 is supplied to the ID extraction and signal switching unit 77. When a still image signal is sent from the still image camera 72, the still image signal is stored in the frame memory 78. The output of the frame memory 78 is displayed on the display 79.
Supplied to The moving image signal from the moving image camera 71 has an ID
It is supplied to the display 80 via the extraction and signal switching unit 77. Thus, the document image captured by the still image camera 72 and the moving image captured by the moving image camera 71 are simultaneously displayed on the display 79 and the display 80. By the way, in the above-mentioned conventional video conference system, when transmitting by the split screen method, when the transmitting side switches between the split combined screen and the screen which is not split combined, Alternatively, when switching between a split-separated screen and a screen that is not split-separated on the receiving side, there is a problem in that the vertical synchronization is lost immediately after the switching and the screen is disturbed. That is, on the transmitting side shown in FIG. 6, as shown in FIG. 7, screens V ₁ and V ₂ having a screen height of 、 and a black level at the top and bottom of the screen are stacked vertically. is split combined screen V ₃ is formed. Therefore, as shown in FIG.
10A, the output of the camera 53 is output with a delay at the timing shown in FIG. 10B, and the output shown in FIG.
The output shown in FIG. 10B is combined with the output shown in FIG. 10B to form the split combined screen shown in FIG. 10C. On the receiving side shown in FIG. 8, a signal to the display 66 is formed at the timing shown in FIG. 11B from the split combined signal shown in FIG.
A signal for the display 67 is formed at the timing shown in FIG. On the transmitting side, as shown in FIG.
The timing of vertical synchronization differs between the output of the camera 52 (FIG. 10A), the output of the camera 53 (FIG. 10B), and the split composite output (FIG. 10C). Also,
On the receiving side, as shown in FIG. 11, the vertical synchronizing timing between the split combined signal (FIG. 11A), the separated signal for the display 66 (FIG. 11B), and the signal for the display 67 (FIG. 11C) is different. Will be different. For this reason, when the transmitting side switches between the split combined screen and the non-split combined screen, or when the receiving side switches between the split separated screen and the non-split separated screen,
Immediately after switching, vertical synchronization is lost. Therefore, the screen is disturbed until the vertical synchronization is stabilized. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a video conference system in which synchronization disturbance is caused and display screen is prevented from being disturbed. According to the present invention, a plurality of cameras 3 and 4, a split synthesizing unit 5 for split synthesizing the outputs from the cameras 3 and 4, an output of the cameras 3 and 4, and a split synthesizing. A signal switching unit 6 for switching the output of the unit 5 according to an instruction is provided on the transmission side, and a split separation unit 31;
A signal switching unit 32, 33 for switching a received signal and an output of the split separation unit 31 according to an instruction, and a plurality of displays 40, 41 are arranged on the receiving side, and a signal from the transmitting side is transmitted to the receiving side via the line 13. This is a video conference system in which a means for muting the displays 40 and 41 corresponding to the synchronization state and the instruction is provided in a part of the transmission path. When the transmitting side switches between the split combined screen and the non-split combined screen, or when the receiving side switches between the split separated screen and the non-split separated screen, vertical synchronization is obtained. Until the operation is stabilized, the video signal level is set to the black level by the blanking processing circuit 11 or the blanking processing circuits 38 and 39. For this reason, the disturbance of the synchronization is prevented from appearing on the screen. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a transmitting side of a video conference system to which the present invention is applied. In FIG. 1, 1A, 1B, 1C and 2A, 2B, 2C are attendees of the conference. The attendees 1A to 1C and 2A to 2C attend the conference side by side as shown in FIG. The attendees 1A to 1C are imaged by the camera 3, and the attendees 2A to
2C is imaged. The output of the camera 3 is supplied to a split synthesizing unit 5 and also to a signal switching unit 6. Camera 4
Is supplied to the split synthesizing unit 5 and to the signal switching unit 6. The split synthesizing unit 5 forms a split synthesized screen by stacking two stages of an imaged screen of the camera 3 whose screen height is １ ／ and an imaged screen of the camera 4 whose screen height is １ ／. The split combined screen is supplied from the split combining unit 5 to the signal switching unit 6. The output of the synchronization control unit 7 is supplied to the cameras 3, 4 and the split synthesizing unit 5, whereby the timing of the synchronizing signal of each output of the cameras 3, camera 4 and split synthesizing unit 5 is controlled. The signal switching section 6 selectively switches between the output of the split synthesizing section 5, the output of the camera 3, and the output of the camera 4. The signal switching unit 6 is controlled by an output of the switching control unit 8. A switching signal is supplied from a terminal 9 to the switching control unit 8. A control signal is generated from the switching control unit 8 based on the switching signal, and the signal switching unit 6 is switched by the control signal. This control signal is supplied to the blanking control unit 10. The output of the signal switching section 6 is supplied to a blanking processing circuit 11. When a blanking signal is supplied from the blanking control unit 10, the blanking processing circuit 11 sets the output signal of the signal switching unit 6 to a black level and performs blanking. The output of the blanking processing circuit 11 is supplied to the CODEC 12, where a high-efficiency encoding process is performed. Output of CODEC12 is line 1
3 is transmitted. When the signal switching section 6 switches between the split composite screen and the non-split composite screen, the timing of the vertical synchronizing signal is different between the split composite screen and the non-split composite screen. Vertical synchronization is lost. Therefore, when a switching signal is supplied to the terminal 9 and the control signal (FIG. 2A) from the switching control unit 8 is switched to switch between the split composite screen and the non-split composite screen, FIG.
As shown in B, a blanking signal is supplied from the blanking control unit 10 to the blanking processing circuit 11 for a predetermined time t until the vertical synchronization is achieved and the operation is stabilized.
Thereby, when switching between the split composite screen and the screen that is not subjected to the split composite, for a certain time t,
The output video signal is set to the black level. The blanking processing circuit 11 is, for example, shown in FIG.
It is configured as shown in FIG. That is, in FIG.
And 22 are PNP transistors. The collectors of the transistors 21 and 22 are grounded. Transistor 2
One base is connected to the terminal 23. Transistor 22
Are connected to the terminal 24. The emitter of the transistor 21 and the emitter of the transistor 22 are commonly connected, and this connection point is connected to the base of the transistor 25 and to the power supply terminal 27 via the resistor 26. The collector of transistor 25 is connected to power supply terminal 27. The emitter of the transistor 25 is grounded via the resistor 28, and the output terminal 29 is derived from the emitter of the transistor 25. The terminal 23 is supplied with a video signal (FIG. 4A) output from the signal switching section 6, and the terminal 24 is supplied with a blanking signal (FIG. 4B) from the blanking control circuit 10. High level L of this blanking signal
₁ is at a higher level than the normal video signal level,
Low level L ₂ is substantially in the black level. When blanking has not been applied, the blanking signal supplied to the terminal 24 is at a high level. Therefore, the transistor 21 turns on and the transistor 22 turns off.
Thus, the video signal from the terminal 23 is extracted from the output terminal 29 via the emitter follower transistor 25. When blanking is applied, the blanking signal supplied to the terminal 24 is set to low level. Therefore, the transistor 22 turns on and the transistor 21 turns off. Since the blanking signal supplied to the terminal 24 is substantially at a black level,
A video signal of a black level is extracted from the output terminal 29. FIG. 5 shows the configuration on the receiving side. In FIG. 5, the image data transmitted via the line 13 is C
Decoded by the ODEC 30. The output of the CODEC 30 is supplied to the split separation unit 31 and the signal switching unit 3
2 and 33. Further, the synchronization signal in the output signal of the CODEC 30 is separated by the synchronization separation circuit 34, and the separated synchronization signal is supplied to the synchronization control unit 35. The split separating section 31 separates the screen that has been split and transmitted, and forms two screens. Output of split separation unit 31 and CODEC
The output of 30 is switched by the signal switching units 32 and 33. The signal switching units 32 and 33 are controlled by the output of the switching control unit 36. The switching control unit 36 is supplied with a switching signal from a terminal 42. The output of the switching control unit 36 is supplied to a blanking control unit 37. The outputs of the signal switching units 32 and 33 are supplied to blanking processing circuits 38 and 39, respectively. The blanking processing circuits 38 and 39 include a blanking control unit 37.
When the blanking signal is supplied from, the output signals of the signal switching units 32 and 33 are set to the black level and blanking is performed. As the blanking processing circuits 38 and 39, those having the configuration shown in FIG. 2 can be used. Outputs of the blanking processing circuits 38 and 39 are supplied to displays 40 and 41. As a result, the screen transmitted via the line 13 is displayed on the displays 40, 4
It is projected on 1. On the receiving side shown in FIG. 5, when switching between a split-separated screen and a screen that is not split-separated, the blanking control section 37 operates the blanking processing circuits 38 and 39 in vertical synchronization. The blanking signal is supplied for a certain period of time until is stabilized.
For this reason, immediately after the switching, the displays 40 and 4
1 is muted, and even if the synchronization is disturbed immediately after the switching, this disturbance does not appear on the screen. In the above embodiment, the blanking circuit is provided on both the transmitting side and the receiving side. However, the blanking circuit may be provided on one of the transmitting side and the receiving side. good. The configuration of the blanking processing circuit is not limited to the configuration shown in FIG. For example, the code indicating the black level may be transmitted from the CODEC 12 immediately after the switching. In the above-described embodiment, the outputs of the two cameras 3 and 4 for imaging the attendees of the conference are transmitted. In addition, a plurality of cameras such as a document camera may be provided. it can. These camera outputs can be transmitted by the still image simultaneous display method. According to the present invention, when the split side is switched between the split-combined screen and the non-split-combined screen on the transmitting side, or when the split-side screen and the non-split-separated screen are separated on the receiving side. Is switched, the video signal level is set to the black level and muted until the vertical synchronization is achieved and the operation is stabilized. For this reason, it is possible to prevent disturbance of synchronization from appearing on the screen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a transmitting side of a video conference system to which the present invention is applied. FIG. 2 is a timing chart used for describing an embodiment of the present invention. FIG. 3 is a connection diagram of an example of a blanking processing circuit according to an embodiment of the present invention. FIG. 4 is a waveform chart used for describing an example of a blanking processing circuit according to an embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a receiving side of a video conference system to which the present invention is applied. FIG. 6 is a block diagram showing a configuration of a transmitting side of a conventional video conference system. FIG. 7 is a schematic diagram used for describing a split screen system. FIG. 8 is a block diagram illustrating a configuration of a transmitting side of a conventional video conference system. FIG. 9 is a block diagram used for explaining a still image simultaneous display method. FIG. 10 is a waveform diagram used for explaining a transmitting side of a conventional video conference system. FIG. 11 is a waveform diagram used for explaining a receiving side of a conventional video conference system. [Description of Signs] 3, 4 Camera 5 Split Combining Unit 11, 38, 39 Blanking Processing Circuit 13 Line 31 Split Separating Unit 40, 41 Display

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-61-83591 (JP, A)                 JP-A-57-63979 (JP, A)                 Shokai Sho 59-153588 (JP, U)                 Shokai 55-133337 (JP, U)

Claims (1)

(57) [Claims] A plurality of cameras, the screen is divided into a plurality of stages in the up-down direction, and the imaging signals from the plurality of cameras are combined for each of the plurality of stages divided in the up-down direction, and the imaging signals from the plurality of cameras are combined. Split combining means for forming a split combined image signal for multiple display on one screen; and selectively switching and outputting each of the image signals from the plurality of cameras and the split combined image signal from the split combining means. A transmitting unit having a first signal switching unit; a receiving unit for receiving a signal transmitted from the transmitting unit; and a split composite image signal received by the receiving unit to separate a plurality of split separated image signals. A split separating unit to be formed, a plurality of split separated image signals from the split separating unit, and a received signal from the receiving unit. A second signal switching means for selectively switching and outputting the signal; and a receiving unit having a plurality of display means for displaying an output signal from the second signal switching means. In a video conference system adapted to transmit to the receiving unit via a line, the splitting is performed from the first signal switching means based on a control signal for controlling a switching operation of the first signal switching means. When the composite imaging signal and each imaging signal from the plurality of cameras are switched and output, the output signal from the first signal switching means is kept for a certain period of time until the state in which the vertical synchronization is maintained. A video conference system comprising a mute means for muting. 2. A plurality of cameras, the screen is divided into a plurality of stages in the up-down direction, and the imaging signals from the plurality of cameras are combined for each of the plurality of stages divided in the up-down direction, and the imaging signals from the plurality of cameras are combined. Split combining means for forming a split combined image signal for multiple display on one screen; and selectively switching and outputting each of the image signals from the plurality of cameras and the split combined image signal from the split combining means. A transmitting unit having a first signal switching unit; a receiving unit for receiving a signal transmitted from the transmitting unit; and a split composite image signal received by the receiving unit to separate a plurality of split separated image signals. A split separating unit to be formed, a plurality of split separated image signals from the split separating unit, and a received signal from the receiving unit. A second signal switching means for selectively switching and outputting the signal; and a receiving unit having a plurality of display means for displaying an output signal from the second signal switching means. In the video conference system configured to transmit the signal to the receiving unit via a line, the plurality of signals are transmitted from the second signal switching unit based on a control signal for controlling a switching operation of the second signal switching unit. When the split separation imaging signal and the reception signal from the receiving means are switched and output, the output signal from the second signal switching means is kept for a certain period of time until the state where the vertical synchronization is maintained. A video conference system comprising a mute means for muting.