JPH09214826A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device in which no synchronization is disturbed due to malfunction of a synchronizing signal separator circuit even when the device is connected to another device and is in use in an abnormal terminated state such as no termination by conducting control to stop the operation of an external synchronization function based on an output of a defective terminated state detection means when a video signal output line is abnormally terminated. SOLUTION: A control section 53 conducts discrimination processing of a terminated state of a video signal output line. When the video signal output line is in a normal terminated state and an external synchronizing signal separated from the video signal by an external synchronizing signal separator section 51 is in existence, the control section 53 controls a selector circuit 54c of a synchronizing signal generating section 54 to activate the external synchronization function. When the output line is discriminated to be an abnormal terminated state, the external synchronization mode is changed into another power synchronization mode or an internal synchronization mode and the control section 53 controls selector circuits 57, 54c so as to set the selecting state in the selected operating mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having an external synchronizing function for synchronizing vertical synchronization with an external synchronizing signal supplied via a video signal output line.

[0002]

2. Description of the Related Art Generally, in a broadcasting station, a studio or the like, a plurality of image pickup devices are controlled by a system controller, and video signals obtained as image pickup outputs by the image pickup devices are switched or used in combination. ing. Then, as one method of applying external synchronization to a plurality of imaging devices connected to the system controller, a method of superimposing an external synchronization signal of a field cycle on a video signal output line and synchronizing vertical synchronization with it (hereinafter, VD
-S method. ).

In the image pickup system adopting the VD-S system, an external synchronizing signal of a field cycle is sent from the system controller side to the video signal output line of each image pickup device. Then, on the imaging device side, the external synchronizing signal sent via the video signal output line is separated from the video signal by the sync separation circuit and supplied to the PLL circuit. Then, the PLL circuit generates a clock signal in phase with the external synchronization signal, so that the external synchronization signal is vertically synchronized.

Here, in the image pickup apparatus used in the image pickup system adopting the VD-S system as described above, the image signal output line is connected to the system controller and is normally terminated. The signal level of the above video signal is specified. The video signal output line of the imaging device is terminated with 75Ω by being connected to the system controller. Then, in the sync separation circuit, for the signal on the video signal output line that is normally terminated on the system controller side, for example, sync tip clamping of the video signal is performed, and further, by slicing at a certain level, external synchronization is performed. The signal is being extracted.

[0005]

By the way, the video signal on the video signal output line of the imaging device used in the imaging system adopting the VD-S system as described above is connected to the system controller and is normally terminated. In the state where the video signal output line is not terminated, the signal level is twice as high as that in the normal termination, and in the state where the video signal output line is doubly terminated, it is normal. The signal level becomes 2/3 times as high as that at the end. Therefore,
In the above image pickup device, it may be used in a state where it is connected to the source of the external synchronization signal and is normally terminated, but the image pickup device itself is used in an abnormally terminated state such as unterminated by being connected to another device such as a monitor device. In this case, the sync separation circuit malfunctions and the synchronization is disturbed.

Therefore, in view of the conventional problems as described above, an object of the present invention is an image pickup apparatus used in an image pickup system adopting the VD-S system, which is not connected to other equipment such as a monitor apparatus. An object of the present invention is to provide an imaging device in which the synchronization separation circuit does not malfunction and the synchronization is not disturbed even when used in an abnormal termination state such as termination.

[0007]

SUMMARY OF THE INVENTION The present invention provides an image pickup apparatus having an external synchronizing function for synchronizing vertical synchronization with an external synchronizing signal supplied via a video signal output line,
Based on the abnormal end state detecting means for detecting the abnormal end state of the video signal output line and the detection output by the abnormal end state detecting means, when the abnormal end state of the video signal output line is present, the external synchronizing function It is characterized by comprising a control means for controlling to stop the operation.

Further, the image pickup apparatus according to the present invention comprises an external synchronizing signal separating means for separating an external synchronizing signal supplied through the video signal output line from the video signal, and an external synchronizing signal separating means obtained by the external synchronizing signal separating means. A synchronizing signal generating means is provided for external synchronization by fixing the oscillation phase to the phase of the synchronizing signal, the video signal output line is in a normal termination state, and the external signal is separated from the video signal by the external synchronizing signal separating means. When the synchronizing signal is present, the control means operates to control the external synchronizing function.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image pickup apparatus according to the present invention will be described below in detail with reference to the drawings.

The image pickup apparatus according to the present invention is suitable for an image pickup system adopting the VD-S system. For example, as shown in FIG. 1, a plurality of image pickup apparatuses 1A, 1B ...
1X are video signal output lines 2A, 2B ... 2
It is connected to the system controller 3 via X, and the video signal output lines 2A,
External synchronization is applied by the external synchronization signal of the field cycle transmitted to 2B ... 2X.

Here, the system controller 3 is
As shown in FIG. 2, a video signal input terminal 3A to which a video signal is supplied from the image pickup apparatus 1A via a video signal output line 2A is terminated by a terminating resistor 131A of 75Ω. The video signal input terminal 3A is connected to the clamp circuit 133A via a DC blocking capacitor 132A and is also connected to the external synchronization signal generator 134A. The clamp circuit 133A sync tip clamps the video signal supplied from the video signal input terminal 3A via the capacitor 132A, and supplies the sync signal to the synchronization cancel circuit 135A. Further, the external synchronization signal generation section 134A generates an external synchronization signal based on the reference vertical synchronization timing signal given by the timing generator 130, and sends it from the video signal input terminal 3A. As a result, the external synchronization signal from the external synchronization signal generator 134A is superimposed on the video signal from the image pickup apparatus 1A. Then, the synchronization cancel circuit 13
5A is supplied with the cancel signal of the external synchronizing signal from the cancel signal generating unit 136A based on the reference vertical synchronizing timing signal given by the timing generator 130, and the clamp circuit 133 is provided.
The external sync signal superimposed on the video signal supplied from A is canceled by a cancel signal to generate a video signal from which the external sync signal has been removed.

The system controller 3 includes a plurality of circuits similar to the circuits corresponding to the image pickup apparatus 1A, and the video signal output lines 2A, 2B, ...
Each imaging device 1A, 1B ... 1X connected via X
An external synchronizing signal having a field period is applied to each of the video signal output lines 2A, 2B ... 2X.

Each of the image pickup devices 1A, 1B ... 1X
Are image pickup devices 1 according to the present invention, each of which is configured as shown in FIG. 3, for example.

The image pickup apparatus 1 shown in FIG.
0, the signal processing unit 20 to which the image pickup output signal obtained by the image pickup unit 10 is supplied, and the image signal output terminal 40 which uses the image pickup output signal subjected to predetermined signal processing by the signal processing unit 20 as a video signal. Video signal output section 3 output from
0, and a clock generation unit 50 for supplying an operation clock to the image pickup unit 10 and the signal processing unit 20.

The image pickup section 10 is, for example, a charge-coupled device (C
A CCD image sensor 11 composed of a CD: Charge Coupled Device is provided as an image pickup device, and an image pickup output signal obtained by this image pickup device is supplied to the signal processing unit 20.

Further, the signal processing section 20 subjects the image pickup output signal supplied from the image pickup section 10 to predetermined analog signal processing such as automatic gain control by the analog signal processing section 21, and then the A / D converter. The image pickup output signal is converted into a digital signal by a digital signal processing unit 22, and a digital signal processing unit 23
Performs predetermined digital signal processing such as gamma correction processing and contour compensation processing, and converts the digital signal processed imaging output signal into an analog signal by the D / A converter 24 and supplies the analog signal to the video signal output unit 30. .

Further, the video signal output section 30 includes an output amplifier 31 to which the image pickup output signal subjected to the predetermined signal processing by the signal processing section 20 is supplied, and the output amplifier 31 outputs the image pickup output signal. The signal is amplified to a predetermined signal level and output from the video signal output terminal 40 via the output resistor 32 having a resistance value of 75Ω.

Further, the clock generator 50 is
An external synchronization signal separation unit 51 connected to the video signal output terminal 40 and an external synchronization signal separation unit 51 connected to the video signal output terminal 40, which has an external synchronization function by a phase locked loop (PLL) suitable for an imaging system adopting the -S method. The external synchronization signal separated by the synchronization signal separation unit 51 is supplied, and the video signal obtained at the video signal output terminal 40 is supplied via the buffer circuit 52. A synchronization signal generator 54,
It is composed of a phase comparison section 55 and the like for performing phase comparison between the synchronization signal generated by the synchronization signal generation section 54 and the external synchronization signal separated by the external synchronization signal separation section 51.

In the external synchronizing signal separating section 51, the video signal obtained at the video signal output terminal 40 is supplied to the buffer circuit 5.
The clamp circuit 51B is supplied via 1A, and the slice circuit 51C is supplied with the video signal sync sync-clamped by the clamp circuit 51B.

Here, in a normal state in which the video signal output line connected to the video signal output terminal 40 is normally terminated with 75Ω, the external synchronization of 2V superposed on the video signal of the signal level of 1.28V is performed. The signal is separated by the external synchronizing signal separating section 51, and a coaxial cable of 5C2V, for example, is used as the resistance value of the video signal output line.
Since the external synchronizing signal considering the resistance value (30Ω) of the cable when used for 500 m is lowered to 1.67 V, the maximum signal level of the video signal is 1.28 V and the minimum signal level of the external synchronizing signal is 1.28 V. By setting the rice level of the slice circuit 51C in the middle of 67V, the external synchronization signal superimposed on the video signal can be separated.

The synchronizing signal generator 54 is a voltage controlled oscillator (VCO) for external synchronization.
54A, a crystal oscillator 54B for internal synchronization, a reference clock signal for external synchronization obtained by the voltage controlled oscillator 54A, and a reference clock signal for internal synchronization obtained by the crystal oscillator 54B. The selector circuit 54C, the timing generator 54D to which the reference clock signal selected by the selector circuit 54C is supplied, and the phase of the vertical synchronizing signal generated by the timing generator 54D are adjusted to the phase comparator 55. And a phase adjusting unit 54E for supplying the same.

The voltage controlled oscillator 54A constitutes a PLL for external synchronization together with the phase comparison section 55, and is supplied with the phase error signal obtained by the phase comparison section 55, whereby The oscillation phase is fixed to the external synchronization signal separated from the video signal by the synchronization signal separating unit 51, and a reference clock signal for external synchronization is generated as the oscillation signal.

Further, the crystal oscillator 54B generates a reference clock signal for internal synchronization as a highly stable oscillation signal by the crystal oscillator.

The selector circuit 54C is controlled by the control unit 53, selects the reference clock signal for external synchronization by the voltage controlled oscillator 54A in the external synchronization mode, and selects the crystal oscillator in the internal synchronization mode. The reference clock signal for internal synchronization by 54B is selected. The selector circuit 54C is adapted to select the reference clock signal for external synchronization by the voltage controlled oscillator 54A even in the power supply synchronization mode described later.

Further, the timing generator 54D generates a horizontal synchronizing signal, a vertical synchronizing signal, and various other timing signals based on the reference clock signal selected by the selector circuit 54C.

Further, as shown in FIG. 4, the phase adjusting section 54E has a shift register 63 which receives the vertical synchronizing signal VD supplied from the timing generator 54D through an inverter 61, and the shift register 63. A delay circuit 64 that further delays the vertical synchronization signal supplied via the delay circuit 64 by a predetermined time, and two-stage buffer circuits 65 and 66 that supply the vertical synchronization signal DLVD delayed by the delay circuit 64 to the phase comparator 55. Composed of. The delay circuit 64 is an analog delay circuit including a resistor R and a capacitor C, and has a horizontal scanning period (0.5.
5H) has a predetermined delay time.

As shown in FIG. 5, the phase adjusting unit 54E uses the horizontal synchronizing signal SYNC including an equivalent pulse supplied from the timing generator 54D through the inverter 62 during the vertical synchronizing period as a clock to shift register. The operation of 63 shifts the vertical synchronizing signal VD by 6 clocks (3H = 3 horizontal synchronizing periods), further delays the signal by the delay circuit 64 for a predetermined time, and outputs the phase-adjusted vertical synchronizing signal DLVD. To generate.

The clock generator 50 also has a power supply synchronizing function for synchronizing with the AC power supply frequency, and is separated from the AC power supply frequency signal supplied to the signal flow terminal 56 by the external synchronizing signal separating unit 51. A selector circuit 57 for switching and selecting the external synchronizing signal and supplying it to the phase comparison unit 55 is provided. The selector circuit 57 is controlled by the control unit 53 and selects the AC power supply frequency signal when the power supply synchronization mode is set.

The control unit 55 is composed of a microcomputer having a built-in A / D conversion function. Then, as shown in FIG. 6, the control unit 55 controls the video signal supplied from the video signal output terminal 40 through the buffer circuit 52 by the A / D conversion function before and after the external sync signal during the vertical sync period. Sampled twice each in
Based on each sample value a, b, c, d, the termination state determination process is performed according to the flowchart shown in FIG.

That is, in the end state determination processing by the control unit 55, starting from the beginning position of one field period, the A / D conversion function performs sampling twice before and after the external synchronization signal during the vertical synchronization period. The sample values a, b, c, d are fetched (step S1).

Next, based on the sample values a, b, c and d, the sync level is calculated by: sync level = (smaller value of a and b)-(smaller value of c and d) Yes (step S2).

Next, it is determined whether or not the sync level calculated in step S2 is within the normal range (step S3). In this step S3, the prescribed value of the sync level in the normal termination state is 40 IRE, the adjustment range is ± 4 IRE, the waveform distortion 2 IRE in the high brightness state, and 40-4-2 = 34 IRE is the minimum value of the sync level in the normal termination state. As a resistance value of the video signal output line, for example, a coaxial cable of 5C2V is 1500
(40 + 4) (105/180) (150/75), considering the cable resistance (30Ω) when used
= 51.3IRE is set to the maximum value of the sync level in the normal termination state, and 34IRE to 51.3IRE are set to the normal termination state.

In the double termination state, (40 + 4)
(2/30) = 29.3 IRE or less Next, and in the unterminated state, (40-4-2) × 2 = 68 IRE or more.

If it is determined in step S3 that the termination condition is normal, the flag indicating the abnormal termination condition is cleared, and the determination process of the termination condition in this field ends (step S4).

Further, when it is determined in step S3 that the terminal is in the double termination state or the unterminating state, the flag indicating the abnormal termination state is set, and the termination state determination processing in this field is performed. Is finished (step S5).

Further, the control unit 55 controls the operation mode switching based on the external synchronization signal separated by the external synchronization signal separation unit 51 according to the flow chart shown in FIG.

That is, in the operation mode switching control by the control unit 55, first, the termination state is determined based on the flag indicating the abnormal termination state (step S11).
When it is determined in this step S11 that the state is the normal end state, it is determined whether or not the external synchronization signal separated by the external synchronization signal separation section 51 is supplied (step S12). Further, in this step S11,
If it is determined that the terminal is in an abnormal termination state, set the power supply synchronization mode other than the external synchronization mode or the internal synchronization mode,
The selector circuit 57 and the selector circuit 54C are controlled so that the selected state in the operation mode is set (step S13).

If it is determined in step S12 that the external synchronization signal is being supplied, the external synchronization mode is set and the external synchronization signal separating section 51 is set.
The selector circuit 57 is controlled so as to select the external synchronization signal separated by, and the selector circuit 54C is controlled so as to select the reference clock signal for external synchronization by the voltage controlled oscillator 54A (step S14). ).

If it is determined in step S12 that the external synchronization signal is not supplied, the process proceeds to step S13 to set a power supply synchronization mode or an internal synchronization mode other than the external synchronization mode, The selector circuit 57 is placed in the selected state in the operation mode.
And controls the selector circuit 54C.

In the power supply synchronization mode or the internal synchronization mode other than the external synchronization mode, the control section 53 determines and sets the setting state by the manual operation of the operation switch 58.

In the image pickup apparatus having such a configuration, the microcomputer mounted as the control unit 53 performs A / D conversion on the sync level of the video signal output,
The termination condition of the video signal output line can be determined, malfunctions due to abnormal termination such as unterminated can be prevented, and the external synchronization function can be operated reliably.

[0042]

In the image pickup apparatus according to the present invention, when the abnormal termination state of the video signal output line is detected based on the detection output by the abnormal termination state detecting means for detecting the abnormal termination state of the video signal output line, Since the control means controls the operation of the external synchronization function to stop, it is possible to prevent malfunction due to abnormal termination such as unterminated.

Further, in the image pickup apparatus according to the present invention, when the video signal output line is in the normal termination state and there is the external sync signal separated from the video signal by the external sync signal separating means, the external sync function is operated. Since the control is performed by the control means, it is possible to reliably operate the external synchronization function.

As described above, according to the present invention, the image pickup apparatus used in the image pickup system adopting the VD-S system is used in an abnormally terminated state such as unterminated by being connected to another device such as a monitor apparatus. In this case, it is possible to provide the image pickup apparatus in which the synchronization separation means does not malfunction and the synchronization is not disturbed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an imaging system adopting a VD-S system.

FIG. 2 is a block diagram showing a main configuration of a system controller in the image pickup system.

FIG. 3 is a block diagram showing a main configuration of an image pickup apparatus according to the present invention.

FIG. 4 is a block diagram showing a configuration of a phase adjustment unit of a synchronization signal generation unit in the image pickup apparatus.

FIG. 5 is a time chart for explaining the operation of the phase adjusting unit.

FIG. 6 is a time chart for explaining the operation of the control unit in the image pickup apparatus.

FIG. 7 is a flowchart showing a termination state determination process by the control unit.

FIG. 8 is a flowchart showing switching control of operation modes by the control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Imaging device 10 Imaging part 20 Signal processing part 30 Video signal output part 40 Video signal output terminal 50 Clock generation part 51 External synchronization signal separation part 54 Synchronization signal generation part 55 Phase comparison part

Claims (2)

[Claims] 1. An image pickup apparatus having an external synchronizing function for synchronizing vertical synchronization with an external synchronizing signal supplied via a video signal output line, wherein an abnormal end state detection for detecting an abnormal end state of the video signal output line. Means, and based on the detection output by the abnormal end state detection means,
When the video signal output line is in the abnormal termination state,
An image pickup apparatus comprising: a control unit that performs control for stopping the operation of the external synchronization function. 2. An external synchronizing signal separating means for separating an external synchronizing signal supplied via a video signal output line from the video signal, and an oscillation phase for the phase of the external synchronizing signal obtained by the external synchronizing signal separating means. The control means is provided with a synchronization signal generating means for applying external synchronization by fixing, and the control means has an external synchronization signal separated from the video signal by the external synchronization signal separating means when the video signal output line is in a normal termination state. The image pickup apparatus according to claim 1, wherein control is performed to operate an external synchronization function at a certain time.