JP3283584B2 - Image receiving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the transmission of image signals, and more particularly to an image transmission system suitable for television broadcasting (TV broadcasting) and cable television (CATV).

[0002]

2. Description of the Related Art In a TV signal transmission system such as TV broadcasting and CATV, a frequency band necessary for analog transmission of a TV signal is about 6 MHz. Even if this is digitized and transmitted, the information amount becomes about 100 Mbit / s. Thus, transmission of a TV signal requires a high-speed and large-capacity transmission path.

In a one-to-many image transmission system, a transmission source transmits an image obtained by editing and synthesizing some images in order to effectively use a limited frequency or line. The editing and synthesis of this image can be classified into two types: an offline type and a real-time type.

The off-line type is a method in which an image produced by editing and synthesizing an image recorded on a video tape or the like is recorded in advance, and at the time of transmission, the recorded image is reproduced and transmitted as it is.

[0005] The real-time type is used for live broadcasting of sports and news, and is a form in which images recorded on a camera or a video tape are reproduced, switched and transmitted on the spot, and used for TV broadcast and CATV communication. This is a processing form that maximizes the immediacy. In the real-time type,
As shown in FIG. 5, a method is used in which signals input from a plurality of cameras (for example, three cameras 1a, 1b, and 1c) are switched by a video switch 2 and then transmitted using a transmission device 3.
Switching by the video switch 2 is performed by the cameras 1a, 1b, 1
This is performed immediately while looking at the image of c. The receiver receives the image transmitted by the receiving device (for example, 5-1) and displays the received image on a monitor (for example, 6-1).

By the switch operation described above, the receiver can feel as if he is operating a plurality of (three in the example of FIG. 1) cameras. However, due to recent diversification of recipient preferences, it is difficult to edit and synthesize an image that satisfies all recipients with one type of switch operation.

[0007] In order to solve such a problem, there are several methods in which a receiver can select a transmitted signal according to his / her preference. In the case of audio, for example, audio multiplex broadcasting performed in TV broadcasting corresponds to this. The receiver can select any of the two audio signals.

[0008] On the other hand, TV broadcasts in Montreal, Canada, have such selectivity for images. In this method, as shown in FIG. 2, a plurality of (for example, three) edited and synthesized images are transmitted, and a receiver selects an image that suits his / her preference by using the selector 14.

[0009]

In order to cope with the diversification of the preference of the receiver, the method of transmitting a plurality of edited and synthesized image signals has the following problems. That is, in order to cope with further diversification of receiver's taste expected in the future, a measure is taken by increasing the number of image signals to be transmitted. However, the frequency band for transmission and the capacity of the transmission line cannot be easily expanded due to the large capacity as described above, and it is difficult to increase the number of image signals to be transmitted.

[0010]

SUMMARY OF THE INVENTION The above-mentioned problem is caused by changing the number of transmission lines of image signals having a large amount of information. The above problem can be solved by transmitting an image using a plurality of fixed number of transmission paths and transmitting those selection signals separately.

[0011]

According to the above-mentioned means, it is possible to increase the types of images edited and combined without changing the transmission path of the image signal, and the receiver selects an image suitable for his / her preference from many edited and combined image signals. It is possible to do.

[0012]

The embodiment shown in FIG. 3 realizes the same function as that of FIG. The part indicated by 10 is the part of the present invention.

The image signals input from the cameras 1a, 1b, 1c are transmitted by the transmitting devices 3a, 3b, 3c via three transmission lines 4a, 4b, 4c, respectively. At the same time, information for editing and combining the images of the cameras 1a, 1b, 1c is transmitted via the transmission path 8 by the switching signal transmitting device 9. Normally, the transmission capacity of the transmission path 8 for transmitting the switching signal is much smaller than the transmission capacity of the transmission paths 4a, 4b, and 4c for transmitting the image signal.

The receiver transmits the three image signals from the transmission paths 4a, 4b, 4c to the receiving devices 5-1a, 5-1b,
Three types of received images 11-1a and 11- received at 5-1c
1b and 11-1c are obtained. On the other hand, the switching signal obtained via the transmission path 8 is received by the switching signal receiving device 14 to obtain the switching signal 16. Previous three types of received images 11-1
a, 11-1b, and 11-1c are received video switches 7-1.
Are switched according to the switching signal 16 that is input at the same time, and is output as one image signal 12-1.
Is displayed.

FIG. 4 shows an example of the internal processing of the reception video switch 7.
Shown in The input image signals 11a, 11b, 11c are each provided with a delay correction circuit 20 capable of freely setting a delay amount.
a, 20b, and 20c. At the same time, the input image signal is input to the synchronization adjustment circuit 23. The synchronization adjustment circuit 23 generates a synchronization signal 24 for synchronizing the three image signals. Delay correction circuits 20a, 20b, 20
In c, by adjusting the amount of delay so as to synchronize with the synchronization signal 24, the image signals 21a, 21b,
21b and 21c are obtained. If this signal is switched by the switch 22 according to the switching signal 16, the edited image 12 can be obtained.

FIG. 5 shows the contents described above in the form of a timing chart. The received image 11a,
11b and 11c cause different amounts of delay due to a difference in a transmission path. This is applied to the delay correction circuits 20a, 20
b, 20c, the image signals 21a,
21b and 21c are obtained. Image signals 21a, 21b, 21
Since c displays the same pixel on the screen at the same time,
Even if the screen is switched in the middle of the screen, the screen is not disturbed. FIG.
9 shows an example in which the switching signal 16 is switched at a position that does not cover the screen, such as a vertical synchronization portion of the screen. In the example of FIG. 5, a1, b2, b3, b4,
The screen is switched in the order of c5 and c6.

The information amount of the image signal is, for example, 100 Mbi.
t / s, the selection signal is, for example, 240 bits.
/ S (one frame: 8 bits per 33 ms) can be transmitted. In the example of switching three cameras, conventionally, 100 Mbit / s in one switching method, 200 Mbit / s in two switching methods, and N in N switching methods.
× 100Mbit / s line was required,
In the example of FIG. 5, almost unlimited switching combinations are possible on a 300 Mbit / s line. The receiver can select the switching signal transmitted that is closest to his or her preference.

FIG. 6 shows a first modification of the embodiment of the present invention. The portion indicated by reference numeral 13 is a portion of the present invention, and FIG. 7 shows its details. The only difference from the embodiment shown in FIG. 3 is the configuration on the receiving side, and the other processes are the same as those in FIG. On the receiving side, in a receiving device with a video switching function, signals are obtained from three types of transmission paths 4a, 4b, 4c and a switching signal transmission path 8, and one image is output. In the embodiments shown in FIGS. 3 and 4, delay correction is performed after converting a received signal into an image signal, whereas in the modified examples shown in FIGS. 6 and 7, the received signal itself is delay corrected. The signals are delayed in the circuits 30a, 30b and 30c and input to the respective receiving devices 5a, 5b and 5c.
The switching signal 1 among the respective receiving devices 5a, 5b, 5c
Only the receiving device selected by 6 performs the receiving operation,
The output is selected by the switch 22. In general, the bandwidth or the amount of information of the transmission signal is often smaller than the size of the image signal or the amount of information of the image signal. Therefore, the delay in the form of the transmission signal requires less capacity or memory of the delay circuit.

FIG. 8 is a modified example of the portion indicated by 13 in the embodiment of FIG. In FIG. 8, a received signal is subjected to delay correction by a delay correction circuit 31 having a high-speed skipping function of a signal, and one signal 2
7 is synthesized. The combined signal 27 is converted into the image signal 12 by the receiving device 5.

FIG. 9 is a timing chart showing the operation of the second modification when an image signal whose transmission time of one frame changes is input. The input signal shown in this example is
Although the average transmission time of one frame as a whole is equal to the same display time of one frame of the TV signal (33.3 ms),
Looking at individual frames, they may be longer or shorter than 33.3 ms. Each of the delay circuits 32a, 32b, 32c always operates with a delay time of a fixed amount or more.

The left part of FIG. 9 shows an example in which the switching signal 16 causes the received signal to be switched from a to b. At this time, the synchronization adjustment circuit 33 reads out the signal 25b at high speed based on the read signal 29b to find the head of the next frame. After that, the end of one frame of the signal 25a is detected, and immediately after the end of one frame of the signal 25a, the signal 25a is detected.
The switch 26 is switched so that the beginning of one frame b comes. When the signal 25b cannot be sent immediately after the signal 25a, the delay correction circuit 32b outputs a dummy signal to maintain the continuity of the signal 27. This dummy signal is a signal that is not used for image reproduction in the receiving device 5.

The second modification has a feature that only one receiver is required as compared with the first modification shown in FIG.

The above-described embodiments and modified examples can be applied to a case where an image signal is transmitted in an analog manner and a case where a digital signal is transmitted. In the case of digital transmission, it is apparent that the present invention is also applicable to a case where an image signal is encoded with high efficiency. The transmission path may be wired or wireless.

In the above-described embodiment and modified examples, the case where three camera inputs are transmitted has been described. However, the number of cameras may be any number. The input device is not limited to a camera, but may be an image recorded on a video tape recorder, an optical disk, a magnetic disk, a semiconductor memory, or the like, or a computer such as computer graphics or an auxiliary storage device thereof, or an image storage connected to the computer. The present invention includes a case where an apparatus or the like is used, a case where an image transmitted through a network or a dedicated line is input, a case where an image that has already been edited and combined, and a case where the image is combined with the input.

In the embodiment, an example has been described in which all the image signals and the switching signals are transmitted through different paths. In addition, when the image signal is multiplexed and transmitted, when the switching signal is multiplexed with the image signal and transmitted, when one switching signal is selected from a plurality of switching signals, and in the above case, Combinations are also included in the present invention. The device transmitting the image signal and the device transmitting the switching signal need not be one device. The device that transmits the switching signal may determine the switching order of the images while receiving the transmitted image signal and view the plurality of displayed images, and may transmit the switching signal.

In the embodiment, the image is switched by the switch 22.
Although this is implemented by using a switch as described above, it is also conceivable to make this into a bus format. That is, in the example of FIG. 4, the delay correction circuits 20a, 20b, and 20c are provided with a function of setting the output to a high impedance state, and all the outputs are connected to one point. Then, only the delay correction circuit whose output is selected outputs, and the remaining delay correction circuits keep the output in a high impedance state. By such an operation, the switch 22
The same operation as in the case of using can be performed. The present invention includes not only the case where the entire screen is switched as with the switch 22 but also the case where a plurality of screens are reduced or deformed and combined into one screen.

The switching signal 16 is received at a timing asynchronous with the input image. In this case, the image may be switched at the timing of the switching signal 16, for example, in the middle of the screen. Instead of the switching signal 16, a signal obtained by delaying the switching signal 16 and synchronizing with the timing of the image may be used. The delay correction circuit may be omitted ignoring the delay between received images.

When the image switching signal 16 is delayed with respect to the image signal, it is necessary to compensate for the delay of the switching signal in the delay correction circuit. In order to measure the delay amount, it is conceivable to insert or multiplex a signal for synchronizing the image signal and the switching signal into the image signal and / or the switching signal. For this, there is a method in which a code (time code, serial number, etc.) for identifying each frame is inserted into an image signal, and a signal for identifying the frame is specified in a switching signal. These methods are also included in this method. .

Although the embodiment has been described with reference to an example in which the switching signal selects only image data, the switching signal may include a signal for instructing which signal is to be received. It is possible. In addition, it is apparent that the present invention includes switching voices, character information, graphic information, still images, data, and the like transmitted in connection with an image simultaneously with an image or individually. The present invention includes a case where these voices, character information, graphic information, still images, data, and the like are transmitted independently of an image, or a case where they are transmitted alone without transmitting an image.

In the embodiment, an example in which the switched image is displayed on a monitor has been described. However, when the switched image is recorded on a video tape, an optical disk, a magnetic disk, a semiconductor memory, or the like, the image is displayed on a computer or the like. The present invention can be applied to processing. Like these,
When used for purposes other than display on a monitor, transmission of one frame is necessarily 33.3 m, which is the display time of the monitor.
It is not necessary to perform transmission in s, and transmission can be performed in a short time using a higher-speed transmission path, or transmission can be performed slowly on a transmission path that is low-speed but has a low communication fee.

[0031]

According to the present invention, a selection signal for selecting any one of a plurality of image signals is transmitted, and the image is switched on the receiving side in accordance with the selection signal. Can be transmitted. Since the amount of information required for transmission of the selection signal is much smaller than that of the image signal, it is possible to easily increase the types of the selection signal, and to easily cope with various requests of the receiver.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional image transmission system.

FIG. 2 is a block diagram of a conventional example of an image transmission system in which an image can be selected by a receiver.

FIG. 3 is a block diagram of an embodiment of an image transmission system capable of selecting an image by a receiver according to the present invention.

FIG. 4 is an explanatory diagram of an image switch portion of FIG. 3;

FIG. 5 is a timing chart for explaining the operation of the image switch portion of FIG. 4;

FIG. 6 is a block diagram of a modification of the embodiment of the present invention.

FIG. 7 is a block diagram of an embodiment of the receiving device with an image switching function of FIG. 6;

FIG. 8 is a block diagram of another embodiment of the receiver with an image switching function of FIG. 6;

FIG. 9 is a timing chart for explaining the operation of the receiving device with an image switching function in FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image input camera, 3 ... Image transmission apparatus, 4 ... Image transmission path, 5 ... Image reception apparatus, 6 ... Monitor, 7 ... Reception image selection switch, 8 ... Image selection signal transmission path, 10 ... Part of the present invention, 13 ... Reception device with image switching function, 15 ... Image selection signal reception device.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N ^7/ 00-7/088 H04N 7/10 H04N 7/16 H04N 5/44-5/46

Claims (4)

(57) [Claims] 1. A means for receiving a plurality of image signals, the double
Switching signal for switching the number of image signals,
Means for receiving a plurality of different combinations,
One of the switching signals received by the receiver
Switching the plurality of image signals according to the
Means for editing and synthesizing the image, and outputting the edited and synthesized image signal.
Image receiving apparatus characterized by having means for force. 2. The image receiving apparatus according to claim 1, wherein said plurality of image signals are transmitted in correspondence with each image signal to be received, voice, character information, graphic information, still image information, or a combination thereof. Switch out in conjunction with switching
Image receiving apparatus, characterized in that the force. 3. The image receiving apparatus according to claim 1, further comprising means for recording the edited and synthesized image signal . 4. An image receiving apparatus according to claim 1, further comprising delay correction means for synchronizing said plurality of image signals, wherein said switching signal is synchronized. An image receiving apparatus for designating switching of the synchronized image signal in a vertical synchronization portion of a screen in the image signal.