JP4486850B2 - Superimposed pulse automatic setting circuit for external synchronization system - Google Patents

Description

  The present invention relates to an improvement of an external synchronization system that realizes synchronization of video signals from video devices such as a plurality of arbitrarily installed cameras by performing external synchronous operation with timing pulses superimposed on the video signals.

Timing when displaying and switching video signals from multiple TV (video) cameras (also simply called cameras), suppressing monitor rolling when recording image signals, and switching screens to memory, etc. For the purpose of matching, a system that externally synchronizes video equipment such as a plurality of cameras is used. As one of the methods, a method of extracting a vertical component timing signal superimposed on a video signal from the image receiving side on the camera side and performing an external synchronous operation using a PLL with this pulse has been put into practical use (described below). Patent Document 1). With this method, by supplying the same reference timing pulse to all cameras, each camera outputs the phase of the generated synchronization signal in accordance with this pulse, so a system for external synchronized operation of multiple cameras Can be easily built. Also, by ensuring the accuracy of the superimposed pulses, not only vertical synchronization but also color lock as a video signal can be performed. It can be said that the video signal output from the device is a high-quality and excellent synchronization method that can satisfy the standard signal as a television signal.
JP 2001-119604 A (paragraph 0013, FIG. 1)

  However, if the timing pulse is superimposed when it is not connected to a device such as a camera that can be externally synchronized with this method, the timing pulse is not synchronized with the video signal, so the timing pulse on the video display screen has a pulse width in the horizontal direction. (The display of the pulse may be clipped to the pedestal level using the erasure circuit and output to the outside of the device, in this case as a black line), and both frequencies appear If they are different, the line moves up and down the screen, making it very unsightly.

  Also, if the frequency is almost the same and the timing of the superimposition pulse happens to be hidden during the blanking period of the video signal, a setting error may occur because the system will not notice asynchronousness if the time has not passed. Therefore, when connecting video equipment such as cameras that do not use this method, it is necessary to make sure that timing pulses are not superimposed, and of course this setting must be changed each time the input camera or other equipment changes. As a result, the manual setting method is very complicated and has limited functions. As a result, it can be said that these settings need to be performed automatically. In addition, although settings of devices such as cameras are being automated, they are not performed on the external device side that superimposes timing pulses.

  An object of the present invention is to solve these problems and to provide a superimposition pulse automatic setting circuit of an external synchronization system that can be easily synchronized without manually switching and setting according to a device such as a camera. To do.

  That is, in the present invention, when a video signal is input, or for each signal channel whose power is turned on and the video signal input can be confirmed, a superimposition pulse as a reference for external synchronization is superimposed on the video signal for a certain period of time. The synchronization state is automatically determined from the relationship of the synchronization signal phase of the video signal. Further, the state where the video signal input can be confirmed is maintained, and the timing pulse is continuously superimposed as long as the synchronization state is determined. According to the present invention, not only the initial setting is automated, but also the setting tracking is automatically performed when the input signal is switched during operation. Therefore, a mixture of input signals of devices that do not accept external synchronization by this pulse superimposition method. In addition, it is possible to provide a circuit that constitutes a device having an affinity.

According to the first aspect of the present invention, the external synchronization is configured such that the video equipment performs PLL external synchronous operation by a timing pulse superimposed on the video signal by a switching unit on synchronization of video signals from a plurality of video equipment. In the superimposed pulse automatic setting circuit of the system,
In response to an input signal from the video equipment, means for starting to superimpose the timing pulse from a state transition time when a video signal is detected from a no-input signal state;
Means for determining a synchronization state from a phase relationship between the superimposed timing pulse and a synchronization signal of a video signal that is the input signal from the video device;
In accordance with the determination result of the means for determining the synchronization state, in the synchronization state, the timing pulse is continuously superimposed, and when synchronization is lost, the timing pulse is stopped.
It is the superimposition pulse automatic setting circuit of the external synchronization system characterized by having .

With this configuration, it is possible to selectively synchronize only video equipment that can perform external synchronous operation, such as unnecessary noise in the screen by switching control of video equipment that cannot perform external synchronous operation. It can prevent the occurrence of harmful effects, and when the signal cable is inserted / removed during camera operation (camera replacement), or when the power is turned on, the video device's synchronization mode can be changed, or video with a different synchronization method can be used. When the device signal is switched in a synchronized state upstream of the switch (that is, when the switch is switched without going through the video signal presence / absence determination), a timing pulse can be superimposed from that point, Timing pulse superimposition on video signals from non-synchronized video equipment can be quickly stopped to prevent adverse effects due to timing pulse superimposition thereafter. .

The invention according to claim 2 is the same as the state transition in which the video signal is detected from the no-input signal state with respect to the circuit system in which the video signal is detected even when the power source on the switching unit side is turned on. 2. The superimposed pulse automatic setting circuit according to claim 1, wherein the synchronization state of the video equipment is determined by superimposing the timing pulse.

  With this configuration, when the video signal switch is turned on, timing pulses can be superimposed from that point.

According to a third aspect of the present invention, the timing pulse is superimposed only during a certain test period from the state transition time when the video signal is detected from the no-input signal state, and the synchronization state of the video equipment is determined during that period. The superimposition pulse automatic setting circuit of the external synchronization system according to claim 1, wherein the determination is performed.

  With this configuration, whether to continue or stop timing pulse superimposition is selected according to the determination result of the synchronization state, and accordingly, if synchronization cannot be achieved, adverse effects due to timing pulse superimposition thereafter can be prevented.

The present invention described in claim 4 is characterized in that the timing pulse is superimposed and a function for judging the synchronization state of the video equipment is provided independently for each video input channel. It is a superimposition pulse automatic setting circuit of the external synchronization system.

  With this configuration, it is possible to determine the synchronization of the video signals of all the connected channels and, as a result, to synchronize the synchronizable channels.

According to a tenth aspect of the present invention, there is provided an external device configured such that the video equipment performs PLL external synchronous operation by a timing pulse in which synchronization of video signals from a plurality of video equipment is superimposed on the video signal by a switching unit. In the superimposed pulse automatic setting circuit of the synchronous system,
In response to an input signal from the video equipment, means for starting to superimpose the timing pulse from a state transition time when a video signal is detected from a no-input signal state;
Means for determining a synchronization state from a phase relationship between the superimposed timing pulse and a synchronization signal of a video signal that is the input signal from the video device;
In accordance with the determination result of the means for determining the synchronization state, in the synchronization state, the timing pulse is continuously superimposed, and when synchronization is lost, the timing pulse is stopped.
It is the superimposition pulse automatic setting circuit of the external synchronization system characterized by having.

  With this configuration, it is possible to selectively synchronize only video equipment that can perform external synchronous operation, such as unnecessary noise in the screen by switching control of video equipment that cannot perform external synchronous operation. It can prevent the occurrence of harmful effects, and when the signal cable is inserted / removed during camera operation (camera replacement), or when the power is turned on, the video device's synchronization mode can be changed, or video with a different synchronization method can be used. When the device signal is switched in a synchronized state upstream of the switch (that is, when the switch is switched without going through the video signal presence / absence determination), a timing pulse can be superimposed from that point, Timing pulse superimposition on video signals from non-synchronized video equipment can be quickly stopped to prevent adverse effects due to timing pulse superimposition thereafter. .

  According to the present invention, by superimposing a pulse at the time of a state transition in which a video signal is input and performing a synchronization determination, a device having an external synchronization function by the superimposed pulse is automatically identified and automatically set. This eliminates the need for manual settings that were necessary in the past, and can provide a system that is easy to handle not only during installation but also when replacing cameras during maintenance.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a basic system configuration in which video signals of respective channels are synchronized by an external synchronization system equipped with a superimposition pulse automatic setting circuit according to the present invention. In this example, the video signal switching device 1 in the case of switching the output signals from three cameras 10, 11, 12 and one VCR (VTR) 17 will be described. The video signal switch 1 includes three mixers 21, 22, 23, three buffer amplifiers (also simply referred to as buffers) 24, 25, 26, three drivers 27, 28, 29, and three superposition control units 18. , 19, 20, a switching control unit 36, and a timing pulse generation circuit 40. The superimposition control units 18, 19, and 20 include determination units 33, 34, and 35 and changeover switches 30, 31, and 32.

  Since each superimposition control unit 18, 19 and 20 has the same configuration, only the configuration of the superposition control unit 18 is shown in FIG. 2 as a representative. The superimposition control unit 18 includes a synchronization separation circuit 56 that separates and extracts the synchronization signal from the output signal of the buffer amplifier 24, two integration circuits 54 and 57 that respond to the synchronization signal separated by the synchronization separation circuit 56, and timing pulse generation A timer 59 that outputs a timing pulse given from the circuit 40 with a predetermined delay, a timer 55 that starts timing in response to the output signal of the integration circuit 54, an output signal of the integration circuit 57, and an output signal of the timer 59 It has an external synchronization determination circuit 58 that determines external synchronization in response, an OR circuit 60 that responds to the output signals of the timer 55 and the external synchronization determination circuit 58, and two change-over switches 53 and 81.

  The video signal switching device 1 shown in FIGS. 1 and 2 is configured to perform synchronous operation of the cameras 10 to 12 by superimposing the pulse supplied from the timing pulse generation circuit 40 on the video signal. Note that the video input terminals of the video signal switching unit 1 are indicated by 13, 14, 15 and the video output terminals are indicated by 37. The camera 12 and the VCR 17 are selectively connected to the video input terminal 15 via a changeover switch (SW) 16 which is a mechanical selection switch. The change-over switches 30, 31, and 32 are timing pulse superimposition setting switches, and the change-over switches 30, 31, and 32 are automatically switched by signals from the corresponding determination units 33, 34, and 35.

  For example, when the movable contact of the changeover switch 16 is on the position “a” side, all the cameras 10, 11, 12 connected to the video input terminals 13, 14, 15 operate so as to be synchronized with the superimposed timing pulse. By switching the video signal at the switching timing synchronized with the timing pulse by the switching control unit 36, the video signal can be switched within the vertical blanking period, and the switched video output signal is output as the video output. It is sent out from the terminal 37. On the other hand, when the movable contact of the changeover switch 16 is on the position b side, the VCR 17 is selected, and the superimposition of the timing pulse on the camera 12 via the video input terminal 15 is automatically stopped. As a result, only the cameras 10 and 11 perform synchronous operation.

  Further, as shown in FIG. 1, the superposition control units 18, 19, and 20 are provided for each channel, so that the synchronization method of the video signals inputted to the respective video input terminals 13, 14, and 15 is different. On the other hand, the switching adapted to the synchronization operation of other channels can be performed without any influence. Therefore, appropriate settings can be made without switching to a display such as an image disturbance due to restart or a setup screen on the video being monitored and displayed.

  Next, the automatic setting operation in the embodiment of the present invention will be described with reference to FIGS. As described above, FIG. 2 shows only the superposition control unit 18 in FIG. 1 and its periphery as a representative, and only the operation with the superposition control unit 18 will be described here. The video input signal from the video equipment such as the camera 10 (see FIG. 1) input to the video input terminal 13 is separated by the sync separation circuit 56 via the buffer amplifier 24. As for the synchronization signal, first, it is determined by the integration circuit 54 that the video signal is input, and secondly, only the vertical component is extracted from the synchronization signal by the integration circuit 57, and the superimposed pulse and external synchronization are extracted. Used to determine whether or not

  The determination of the video signal being input, which is the first purpose, is performed by first detecting the timing at which the signal is input from the no-signal input, that is, when the signal cable is inserted / removed while the device system is operating, that is, This is to configure a start-up circuit, in other words, to superimpose pulses for the set time of the timer 55 at each subsequent stage when the camera is replaced or, of course, when the camera is turned on. Has been automated. That is, the integration circuit 54 has a long time constant that can be stabilized in terms of level during a certain period of the synchronization signal, and detects both the edge of the video signal that has changed from being absent to being present and the continuous connection state. have. As long as this video signal maintains the connection, the detection state does not change. Next, since it is necessary to continue superimposing until the PLL lock of the camera 10 is stabilized, the set time of the timer 55 is set to several seconds. The superimposition pulse is stopped not only when a video signal whose external synchronization is not based on the superimposition pulse is input, but also when the input signal from the camera 10 or the like cannot be obtained, only the pulse of the device such as the camera 10 is stopped. This is also to prevent the synchronization separation circuit 56 from continuing to malfunction when input to the signal processing circuit.

  The second purpose of external synchronization determination is to compare the phase with the vertical component, but at the start of the vertical synchronization signal, it is always determined that the superposition pulse is widened by the timer 59, so that the external synchronization state To monitor. When the phase relationship that happened to be synchronized with the video signal of a device such as another camera (not shown) that does not depend on the superimposing pulse method is lost, of course, the signal from the synchronized camera 10 is lost, When the disconnection is detected, it is determined to stop the superposition of pulses. If the video signal of a video device such as the camera 10 using the superimposition pulse method is determined to be out of sync due to the influence of noise that happens to be superimposed, the pulse will not be superimposed again and the synchronization system will be turned on and off again. Therefore, if it is impossible to establish without making a determination based on the test period again, the original purpose of external synchronization of a plurality of video input devices by pulse superimposition is lost. Therefore, in the present invention, the continuous superimposition of the pulses can be stopped and restarted by the constant determination by the external synchronization determination circuit 58.

  As described above, when it is necessary to superimpose pulses according to these determinations, the changeover switch (SW) 53 is closed so that the superimposed pulse from the timing pulse generation circuit 40 can be transmitted to the driver 27 via the OR circuit 60. A pulse is superimposed on the video signal line by the function of the device 21. In addition, as an operation when the power source of the device having the superimposition control unit 18 is turned on, a pulse from the timing pulse generation circuit 40 may be delayed due to loading of a system program of a video device such as the camera 10 or the like. When the start-up is arbitrarily required by the cooperative operation, the pulse overlap test period can be freely given by inputting the start-up signal to the reset signal input terminal 70 after these processes are completed. It is.

  As described above, when the camera of the external synchronization system using VCR and superimposition pulse is switched by a switch, etc., it is automatically switched on / off of pulse superimposition. If the connection is known, there is no need to superimpose pulses, and superimposing pulses will be mixed into the image if superimposition is performed every time the video signal switches, even during the test period. Pulse superposition can be arbitrarily cut by the changeover switch 81. On the other hand, devices that require a time longer than the average test period for the convergence speed of the PLL performed by devices such as cameras connected in reverse, or the time from the start of the device to the start of the PLL operation even if the convergence of the PLL is early If it is not possible to bring in the external synchronization status judgment within the test period on the superimposition side and the pulse superimposition is completed within the test period on the superimposition side, synchronous operation cannot be continued. In addition to the mode, the changeover switch 81 can be operated to arbitrarily execute pulse superposition.

Next, synchronization determination will be described in more detail with reference to FIG.
First, the superimposed pulse (waveform A) is superimposed on the video signal (waveform B) from the camera to form a superimposed waveform (waveform C) of the superimposed pulse. In a camera or the like, an externally synchronized PLL circuit starts synchronous operation with a superimposed pulse, and when synchronized, a phase relationship in a synchronized state is established (waveform D). Since an externally synchronized PLL circuit such as a camera performs phase control so that the falling phase of the superimposed pulse is approximately the start phase of vertical synchronization, this relationship is constant when synchronized and is therefore separated from the video signal. The level of the external synchronization determination timing (waveform G) generated from the superimposed pulse is H in the timing (waveform F) of the vertical synchronization signal obtained by integrating from the composite synchronization signal (waveform E). Determine synchronization status.
The external synchronization determination timing (waveform G) spreads in the delay direction by the timer, and the range for determining the phase coincidence with the superimposed pulse also expands. However, since the detection delay of general vertical synchronization is within 0.5H, When the delay of the timer is selected to this extent, the superimposed pulse is in the vertical blanking period and does not appear on the display screen, so there is no problem.

  Similarly, if the relationship between the superimposed pulse and the video sync signal between systems that are not synchronized happens to be in the phase matching range, it does not appear on the display screen, so there is no problem and the synchronization status is monitored as it is. In response to this, control of pulse superposition is performed.

  Next, the basic flow of automatic pulse setting (when AUTO is set) by the superposition control unit 18 will be described with reference to FIG. When this is automatically determined by the connection of a device such as the camera 10 corresponding to the superposed pulse, first, in step S1, it is detected that the input state is established by video input detection. Next, in step S2, the timing at which the video input change detection is switched from “no” to “present” is detected. That is, when a device is connected to the video input terminal 13 that has not been connected until now to input a video signal, or in order to change the device for video input, the previously connected device is once disconnected Is determined when the input signal from the device is input, or when the video device to be input is turned on, the test period timer is started in step S3, and the condition flag 1 is pulse-superimposed in step S6. Set a flag.

  In the condition flag determination in step S8, when at least one of the condition flags in step S6 or step S7 has a pulse overlap flag, pulse overlap is performed and the process returns to the top of the flow. At the time of activation, the route of steps S1, S2, S3, S6, and S8 is followed. Next, since the video input is detected in the same manner, the process goes to step S2 again to move to video input change detection. However, since the video has already been input, the test period is determined in step S4 by the test period determination. If there is, the pulse superposition is continued. If time-out occurs, the pulse superposition is stopped by setting the pulse stop flag of the condition flag 1 in step S6. In addition, it is possible to detect the start-up of the power source of the video signal switching unit 1 in step S1 and to deal with it similarly to the video input change detection in step S2.

  That is, in the test period, steps S1, S2, S4, S6, and S8 are followed. At the same time, when a device such as a connected camera enters a test period and performs synchronous operation and the phase relationship between the superimposed pulse and the video synchronization signal is established, the pulse superimposition flag of the condition flag 2 is determined in step S7 based on the external synchronization determination result in step S5. Stand up. In the condition flag determination in step S8, the pulse superimposition is determined when the pulse superimposition flag is obtained from the information of any of the condition flags. Therefore, the pulse superimposition flag of the condition flag 2 may be set before the test period ends. If it is possible, pulse superimposition will continue to be performed on the connected device. That is, steps S1, S5, S7, and S8 are followed.

  Conversely, if synchronization is not obtained in the external synchronization determination in step S5 within the test period and pulse superposition is not continued, it is determined that the connection target device is not an external synchronization system based on pulse superposition, and step S1 , S2 and S4, pulse superposition is not performed until the change in the video input in step S2 is obtained again.

  According to the present invention, it is possible to selectively synchronize only video equipment that can perform external synchronous operation, unnecessary noise in the screen by switching control of video equipment that cannot perform external synchronous operation, etc. Therefore, the present invention is useful in a system for synchronizing a plurality of video devices such as a camera.

The block diagram which shows the basic system configuration | structure of the superimposition pulse automatic setting circuit of the external synchronization system concerning embodiment of this invention The block diagram which shows the structure of the superimposition control part in FIG. Phase relationship diagram for explaining the operation state of the circuit of FIG. 1 and FIG. Basic flowchart showing the operation of the circuit of FIGS.

Explanation of symbols

1 Video signal switcher 10-12 Camera 13-15 Video input terminal 16, 30-32, 53, 81 Changeover switch (SW)
17 VCR
18 to 20 Superimposition controller 21 to 23 Mixer 24 to 26 Buffer amplifier (buffer)
27 to 29 drivers 33 to 35 determination unit 36 switching control unit 37 video output terminal 40 timing pulse generation circuit 54, 57 integration circuit 55, 59 timer 56 synchronization separation circuit 58 external synchronization determination circuit 60 OR circuit 70 reset signal input terminal

Claims (4)

In the superimposed pulse automatic setting circuit of the external synchronization system configured to perform the PLL external synchronization operation by the timing synchronization pulse of the video signal from a plurality of video devices, the timing pulse superimposed on the video signal in the switching unit,
In response to an input signal from the video equipment, means for starting to superimpose the timing pulse from a state transition time when a video signal is detected from a no-input signal state;
Means for determining a synchronization state from a phase relationship between the superimposed timing pulse and a synchronization signal of a video signal that is the input signal from the video device;
In accordance with the determination result of the means for determining the synchronization state, in the synchronization state, the timing pulse is continuously superimposed, and when synchronization is lost, the timing pulse is stopped .
A superimposed pulse automatic setting circuit for an external synchronization system, comprising:   Even when the power source on the switching unit side is turned on, the timing pulse is superimposed on the circuit system that has detected the video signal, as in the state transition in which the video signal is detected from the no-input signal state. The superimposition pulse automatic setting circuit of the external synchronization system according to claim 1, wherein the synchronization state of the video equipment is determined.   2. The method according to claim 1, wherein the timing pulse is superimposed only during a certain test period, and the synchronization state of the video equipment is determined during that period, starting from the state transition when the video signal is detected from the no-input signal state. The superimposition pulse automatic setting circuit of the external synchronization system described in 1. 2. The superimposition pulse automatic setting circuit of the external synchronization system according to claim 1, wherein a function for superimposing the timing pulse and determining a synchronization state of the video equipment is provided independently for each video input channel.