DE2640019A1 - Video telephone conference system - has TV cameras viewing participants and signals multiplexed over telephone to produce composite image of participants on screen - Google Patents

Abstract

The video telephone conference system allows any individual participant in the conference (or a document) to occupy the entire screen or to have four or more participants occupying a split-field screen simultaneously. Four tv cameras view the e.g. four participants. The signals from each camera are multiplexed over the telephone link to the receive demultiplexer where they can be displayed on a split screen etc. The relationships between fields and sync. pulses are specified.

Description

Television conference arrangement using shared facilities

of video telephony The invention relates to a television conference arrangement with shared use of video telephony facilities, with at least A multi-person conference facility is connected to one end of the line is, of which the individual images can optionally be combined to form a collective image. In such a meeting room conference, at least two are at different Spaces located in the locations are connected to each other in terms of images and acoustics. Included it is advisable to transmit only a single video signal in each direction. For this purpose, it is not just the picture of a speaker or a drawing that fills the format reproduced on the screen, there is also the possibility of collective image transmission, in the case of several images of the. Conference participants zoomed out next to or on top of each other arranged on the screen.

Such a collective image transmission of four or nine individual images is described, for example, in DU-PS 2 104 337. The image signals of the individual conference participants on suitably arranged next to and one above the other Monitors reproduced. A collective image camera is located in front of these monitors, which records the image of the entire arrangement and transmits it to the remote station. These The solution therefore requires one monitor for each conference participant and one additional monitor Recording camera per meeting room. In addition, there are additional losses in quality by the further required signal conversion.

As part of the electronic collection of images, today Commercial studio technology declined the individual images that were put together to form an overall image are recorded by cameramen. The television camera is set up like this the object to be recorded, that there is enough space available for it, e.g. the right upper quarter, optimally filled in the viewfinder. The other cameras will too based on specific criteria. Now you can switch by means of electronic switching the required image excerpts from the individual cameras to form an overall image join together. An aid is required for conference calls with video telephones not feasible by cameramen.

Therefore, for example according to Bell Lab Rec. Jan 1970, pp 19-22, Several conference participants are put together in such a way that they can be viewed from one camera be recorded together. The disadvantage here is that there are conference participants can sometimes only see the monitor image from the side and the large viewing distance makes the displayed image appear very small.

In order to avoid these disadvantages, it is proposed in GB-PS 1,173,918 been, the collective picture of the conference participants in a meeting room electronically put together. For this purpose, ur generating a quad image is the speed the vertical and the horizontal deflection are doubled. While one picture is one Tone participant is scanned, the scanning beams of the other images suppressed so that each frame is reduced to a quarter of the total size appears in a collective image. Such an image scan has the disadvantage that no commercially available recording cameras can be used, but those that allow double resolution. In this way, the scanning standard is also correct The camera does not match that of the playback device, so that in a meeting room conference Two different types of recording cameras are to be provided, one for single images and one for sticker pictures.

The object of the invention is to provide a television conference arrangement, in which either single images, e.g. also of drawings, are viewed 1 or several individual images, for example four or more, electronically to form a collective image can be put together.

This is achieved according to the invention in that in the conference facility to record the individual images recording cameras are used with which the recorded Object is optionally reproduced reduced, that when switching to collective image also the image scale is switched, in such a way that each recorded Object is reduced in such a way as it appears in the collective image, whereby it is in the In the middle of the storage layer (target) of the recording camera appears' that a central electronic image switch is provided when switching to collective image the individual clock generation of all individual recording cameras for image scanning first switches off at a defined point - and switches to external clock reception, that the electronic changeover switch after a protection time, in which also the last Recording camera must stop, a clock to the first recording camera that the first Sub-image of the first row of the collective image supplies, for the external clock control of this Creates the recording camera and starts the image scanning of this recording camera, that the electronic changeover switch a time thereafter, which corresponds to the time in which the first reduced field was scanned, in the same way the same Clock applied to the second recording camera, after the same time to the third etc., until all the cameras in the first row of the collective image scan their images, that after a time equal to the scanning time of the visible images of the first row of the The collective image corresponds to the clock to the recording cameras of the second partial image row is applied in the same way one after the other, then to the recording cameras of the other Sub-image series until all recording cameras are controlled externally, that the electronic one Switch the recording cameras in the same order as they are on the external one Clock control were connected, line by line for image signal transmission to the Acceptance line after a delay time that is not the same as the sampling time corresponds to the image parts to be reproduced above and to the side of the reduced object image, switches through and in this way composes the collective image, and that the electronic Changeover switch supplemented the collective image signal with horizontal and vertical blanking pulses forwards until switched from collective image to single image or the television conference is terminated.

The conference facility in the meeting room contains several video telephones uniform construction, which is also used by participants are set who are not attending a television conference.

This has the advantage of uniform spare parts storage and Willingness to repair. There are recording cameras with switchable electrical Enlargement of the scanning field is common, so that also the recording cameras in their standard do not need to be changed. You can use both to take a single image as well as a collective picture can be used.

The telephones of the conference facility only need through one central electronic image switcher to be added to the individual recording cameras starts, synchronized and during the phase shifted in a suitable manner respective image scanning ensures the transmission of the correct image signals.

According to a further development of the invention, each has a conference space its own standardized video telephone, with the individual video telephones and the electronic picture switcher in the middle of an approximately round table are arranged. This has the advantage that images of documents from each individual Conference place can be transferred from without the need to a special one Additional device for document transmission to have to go.

The electronic image composition described is not just for four conference places in the conference room applicable, but also in the same way for nine. However, the images appear even smaller than in the case of four, so that even if there are more than four conference participants, all participants are not shown will. However, the same people are not always visible in the collective image to make, it is proposed according to a development of the invention, the collective image voice-controlled compose from the pictures of the three people who were last have spoken, and the image of what is still speaking. This has the advantage that the active conference participants can be seen on the screen more often and longer than the only listeners.

Further advantages and additional refinements of the invention go from the following description in which an example of the invention is based of the figures is explained.

1 shows a video conference between a meeting room shown with four conference seats and a distant individual participant. Based 2 explains which part of a single image is used to assemble a Collective image is used, and on the basis of Figure 3, which signals arise.

Only the details necessary for understanding the invention are shown in FIG shown, all others are already known and therefore not further described here.

On an approximately round, e.g. four or octagonal table T four television telephones FA to FD are arranged. In front of each of these amber telephones a conference participant sits.

All Pernsehtelephones are with an electronic picture switcher U connected. This switch U switches in the manner described below Signals that come from the individual recording cameras are combined and routed for your own control optionally to the screens of the television telephones FA to FD, to which the above-mentioned recording cameras belong, and via a line s that also includes one or more switches to a single subscriber to the video phone FE. A collective picture is shown on this video telephone. On the screens the television telephones FA to ED can also display the picture of the conference participant on the video telephone E are shown.

In such video telephone conferences, a conference participant usually leads the chair and determines at the push of a button whether an individual conference participant, a drawing presented by them or a collective picture on everyone's screen people involved in the conference should appear. But it is also possible especially with voice-controlled television conferences, the picture of the respective league The speaker on the screens as long as no collective image is transmitted. For these cases, an additional signal is usually provided for the respective participant indicates that he is being observed by at least one other conference participant.

In addition, the arrangement is set up so that when switching on Document viewing, switching off the collective image and playback at the same time of the document takes place in full format.

If a collective image is now to be generated, the property made use of the video telephone to reduce the image of a conference participant. This creates an image as shown in FIG. Since the area N is only a quarter of the screen area should take, only the middle part of the picture is used, in such a way that a quarter of the top, a quarter of the bottom, a quarter of the left, and a Quarter of the right picture area is not used. On all four sides of the picture a quarter of the rows and columns are not used. With these figures For the sake of simplicity, no mention is made of the retrace time of the scanning beam, although as usual, it is always present.

The functioning of the electronic picture switch is based on the curve in Fig. 3. The curve a shows the image signal and the blanking pulses, which were recorded by the recording camera of the video telephone FA. Accordingly the curves b, c and d come from the recording cameras FB, FC and FD.

It is now assumed that each of the four recording cameras of the conference facility delivers single images that fill the format on the screens of the individual video telephones be reproduced. Each of the four cameras works independently of one another. Each recording camera produces its own clock, so that the horizontal impulses As a rule, h and vertical impulses v of the individual images do not match.

If you now switch to the collective image, these impulses must be absolute are generated synchronously with each other and may be mutually exclusive in curves a to d don't move.

For this purpose, the electronic picture switch U sends a stop request to all four cameras. With this command, the pulse generation is defined on a Place stopped, namely on the trailing edge of the vertical sync pulses vl. Da the video telephones usually work with two fields, is the exact definition of the vertical sync pulse vl before the first field selected slightly larger than the sync pulse v2 before the second field.

Every recording camera consequently has the ability to find the right point where to stop sampling.

Since the individual recording cameras, as already described, have their blanking pulses at different times, a protection time SZ is provided that is at least a full screen duration. During this time, all recording cameras will then reach the Moment to stop.

At this moment, each of the recording cameras switches from self-clock generation of the basic clock to an input via which this basic clock is applied externally can be. This basic clock is usually 2.048 MHz.

During the protection time SZ, the stop request is also activated the command was given to the individual cameras, the one that was previously recorded in full format To shrink the object. Because the collective image is composed of four individual images should be, the side length of the picture is to be reduced to half. That can either take place in that a wide-angle lens is placed in front of the recording camera or by electrical means by increasing the deflection voltage of the camera, so that in each case an image as shown in FIG is scanned, as before that which was not reduced in size.

After these preparatory measures, the electronic switch starts U the individual cameras by being connected to them from an appropriate point in time to a basic clock generated by the external input of the video telephone. First of all, the picture speaker FA according to FIG. 3f is supplied with the basic clock. After the time has elapsed, the video telephone receives a duration of half a line length FB according to FIG. 3g this clock. The two recording cameras are started and you begin line by line with a vertical pulse vi on the storage layer to scan objects depicted.

As soon as the recording camera of the video telephone FA is half of the Has scanned lines, i.e. after the duration of half a field, comes also the scanning camera of the video telephone BC the basic clock according to FIG. 3h and a another half a line length afterwards also the recording camera of the video telephone FD, as can be seen from Fig.3i. From this point on, all four are recording cameras active again. But they work synchronously and out of phase.

The electronic image switch U must now from the Bfldsignalen the four individual cameras each select the appropriate image signals, them with the vertical impulses vl and v2 as well as the horizontal pulses h veb see, and to everyone at the television conference send out the screens involved. This is done in such a way that the switch U, as indicated in Fig. 1, alternately each one image line of the image N (Fig. 2) for assembling the collective image and from it an image signal according to FIG. 2e forms. Because the top quarter of the frame and also the first quarter of each Line does not appear in the collective image, the image signal of the collective image mushrooms begins after the vertical pulse vl with the line of the Bild.N of the scanning camera of the video telephone FA, which is denoted by A in curve e.

This is followed by the visible line B of the video telephone FB at.

After a line return during the horizontal pulse h appears the next line of the two recording cameras on the screen and so on until the visible ones Images N scanned by the first two cameras are fully reproduced are.

Taking into account the delay time 1 / 4V and 1 / 4h appear in the next picture lines the visible pictures, those in Fig. 3e with the letters C and D are marked.

After the end of the first field I, the vertical pulse v2 is transmitted and then the ropes of the picture that belong to the second field, etc., until the collective image transfer is finished.

In Fig.1 a round table is shown at which four conference participants sit opposite. The table can also have a different shape, in which case however, the four conference participants cannot view it directly.

These four conference participants can also be in different Spaces sit. It should be noted, however, that there is also a control of the must be, which determines whether individual images or a collective image is transmitted. He then sets the electronic screen switch U in motion at the appropriate moment, so that it carries out the control processes described. If this is the case, transmission runtimes If there should be an image shift, this must be corrected accordingly the start times are balanced again. For small distances that could With the help of a manual correction ', a correction signal must be applied for larger ones the individual video telephones are transmitted.

If the person sitting away from the conference facility described Conference participants with the video telephone FE from single image to collective image or the other way around, he must inform the chairman of the meeting, who makes the switchover, usually notify acoustically so that the latter can switch over can make. Otherwise he only ever gets to see the picture on his screen, determined by the conference leader. This conference participant could also with a command in the image signal, bypassing the conference leader, the image type and / or choose the picture.

If more than four video telephones are installed on the conference table T, so the electronic image switch U can be designed so that it always makes a selection of four images. The selection can be acoustically, for example take place in that the image of the last four speakers is transmitted in the collective image will. After each conference participant not only have a video phone individually has in front of him, but also a microphone, this selection can be based on the speech volume determined by the individual microphones.

So that the picture is not switched too often and thereby If there is restlessness on the screens, it is advisable to make brief statements Conference participants who are less than a certain period of time are not to be taken into account. In addition, a switchover can be made after a certain delay time -will.

As soon as from a collective image viewing to single image, in particular If you also switch to document viewing, the wide-angle effect becomes the Recording cameras at the same time automatically reversed, so that the object reappears on the screen in full format.

7 claims 3 Piguren L e r s e i t e

Claims (2)

P a t e n t a n s p r ü c h e 1) Television conference arrangement with shared use of video telephony equipment, at least at one end of which the Line is connected to a conference facility for several people, of whom the individual images can optionally be combined to form a collective image, d a d u r c h e k e n n n z e i n e t that in the conference facility to accommodate the Single images recording cameras are used, with which the recorded object optionally reduced again is given that when switching to collective image also the image scale is switched, in such a way that each recorded object is reduced (N) as it appears in the collective image (to a quarter), where it appears in the middle of the storage layer (target) of the recording camera (Fig. 2), that a central electronic 3ildumschalter (U) is provided, which when switching The individual clock generation (basic clock) of all individual recording cameras on the collective image (2A ... PD) for image scanning initially at a defined point (end of the vertical pulse after the second Ralbbild) - and switches to external clock reception that the electronic changeover switch (U) after a protection time (SZ), in which the last recording camera t? A ...? D) must stop, one cycle (basic cycle) to the first Recording camera (PA) showing the first (left) partial image of the first (top) row of the Provides collective image, for the external clock control of this recording camera (FA) creates and so the image scanning of this recording camera (FA) starts that the electronic Toggle switch (U) a time after that, which corresponds to the time in which the first reduced Field was scanned (half a line length), in the same way the same Cycle to the second recording camera (FB), after the same line to the third etc., until all of the recording cameras (2) in the first (top) row of the collective image are theirs Scan images that after a time equal to the scanning time of the visible images (N) corresponds to the first (top) row of the collective image (half field), the clock to the recording cameras (FC FD) of the second partial image row in the same way one after the other is created, then to the recording cameras of the other partial image rows until all Recording cameras are controlled externally that the electronic switch (U) the Recording cameras (BA ... ED) in the same order as they are sent to the external clock control were connected, line by line for the transmission of the image signal to the tapping line respectively after a delay time that is not the sampling time Parts of the image to be displayed above (1 / 4V) and to the side (1 / 4H) of the reduced object image (N) corresponds, switches through and in this way composes the collective image, and that the electronic switch (U) the collective image signal (Fig.3e) with horizontal and vertical blanking pulses (vI, v2, h) supplemented forwards until from the collective image switches to single image or the television conference is ended. 2) television conference arrangement according to claim 1, d a d u r c h g e -k It is noted that the horizontal sync pulse of the camera was before the first Field (I) can be distinguished from the sync pulse (v2) before the second field (II) is formed, preferably is wider. )) Television conference arrangement according to claim 1, d a d u r c h g e -k One of the signs that every conference space is equipped with a standardized video telephone (FA .. .FE) is equipped, the individual video telephones and the electronic Changeover switches (U) are arranged in the middle of an approximately round table (T). W) television conference arrangement according to claim 1, for more than four conference places, d u r c h e k e n n n z e i c h n e t that the collective image is voice-controlled is composed of the images of the four people who spoke last or still speak. >) Television conference arrangement according to claim 4, d a d u r c h g e -k e n n n z e i n e t that a switchover of the individual images that make up the collective image is composed, takes place after a time delay. ;) Television conference arrangement according to claim 4, d a d u r c h g e -k It is noted that regardless of the image on the respective screen Attention signal is given at every conference place, whose picture is at least can be seen on one of the screens. ) Television conference arrangement according to claim 1, d a d u r c h g e -k It is noted that when switching to document viewing at the same time a switchover from collective image to single image takes place, with the reduced Object display is switched back to normal size.