JPH01213075A - Television image pickup device - Google Patents

Abstract

PURPOSE:To automatically correct the delay time error of a video signal in a camera cable or a processing amplifier, etc., by providing a camera head part with the addition circuit of a horizontal synchronizing signal, and providing a camera control unit with a synchronizing signal separator circuit. CONSTITUTION:The addition circuit 1 of the camera head part 108 mixes the horizontal synchronizing signal HD1 to the video signal, and generates a composite video signal, and this signal is transmitted to the camera control unit 115 through a buffer amplifier 107 and a coaxial cable 119 as being delayed. Next, the synchronizing signal separator circuit 2 of the unit 115 separates the signal HD1 mixed in the composite video signal, and supplies it to the input terminal of one side of a phase comparator 114. Besides, the horizontal synchronizing signal HD2 from a synchronizing signal generation circuit 110 is supplied to the input terminal of other side of the comparator 114. Then, the signals HD1 and HD2 are controlled so that their phases perfectly coincide through the comparator 114, a voltage controlled oscillator 103 and the synchronizing signal generation circuit 104. Thus, the delay time error of the video signal in the cable 119 or the processing amplifier 111, etc., can be automatically corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television imaging device, and more particularly to a separate type television imaging device that corrects delay time errors of video signals in camera cables and the like.

[Conventional technology]

In so-called separate type television imaging devices in which the camera head and camera control unit are separated, changing the length of the camera cable causes an error in the propagation delay time of the video signal, and each time this propagation delay time error increases. I had to adjust the circuit to compensate. This not only complicates the operation of the television imaging apparatus, but also has the drawback that the propagation delay time error cannot be adjusted with high accuracy. Particularly, in cases such as high-definition television, where signal processing such as optical plaque clamping must be performed on the video signal with high accuracy, the fat woman problem has arisen.

FIG. 3 is a block diagram showing a first conventional separate type television imaging device.

This first conventional example uses a solid-state imaging device (hereinafter referred to as COD) as an example.

In FIG. 3, a first conventional separate type television imaging device includes a lens 101 for projecting a subject, a CC
D imaging device 102, voltage controlled oscillator 103 whose oscillation frequency changes depending on the control voltage, and voltage controlled oscillator 1
A synchronous signal generation circuit 104 is supplied with the output of 03 and generates a predetermined pulse group, and a COD is supplied with a predetermined pulse group from the synchronous signal generation circuit 104 and generates various clock pulses necessary for driving the CCD imaging device 02. The camera head unit 10 includes a driver 105, a preamplifier 106 that clamps and samples an amplitude-modulated video signal from the CCD imaging device 102, amplifies it, and converts it into a video signal of a predetermined level, and a buffer up 107.
8 is configured, and then a master oscillator 109, a synchronization signal generation circuit 110 which is supplied with the output of the oscillator 109 and generates a predetermined pulse group, and a process that performs optical blank cranking, g/ma correction, etc. on the video signal. Amplifier 111
, an adder circuit 112 that adds a composite synchronization signal to the video signal from the process amplifier 111, and a buffer amplifier 113.
and the horizontal synchronization signal from the synchronization signal generation circuit 104) (D
1 and the horizontal synchronization signal HD2 from the synchronization signal generation circuit 110.
control voltage VCONT according to the phase error by comparing the phases of
A camera control unit) 1.15 is configured with a phase comparator 114 that generates
and camera control unit 115 are camera cables 1.1
Connected by 6. This camera cable 116 is connected to a cable 117 that applies the control voltage VCONT from the phase comparator 114 to the voltage controlled oscillator 103, and a cable 117 that applies the control voltage VCONT from the phase comparator 114 to the voltage controlled oscillator 103, and a cable 117 that applies the control voltage VCONT from the phase comparator 114 to the voltage controlled oscillator 103.
4 and the buffer amplifier 107
A coaxial cable 119 for transmitting a video signal from the input terminal to the process amplifier 111 is integrated with the coaxial cable 119.

FIG. 4 is a time chart showing the operation of the first conventional example.

The time chart in FIG. 4 shows waveforms of various parts in one horizontal scanning period. Hereinafter, the operation of the first conventional separate type television imaging device will be explained using the time chart shown in FIG.

First, the horizontal synchronizing signal HDI' at the output of the synchronizing signal generation circuit 104 (point ■) and the output of the buffer amplifier 107 (
The phase relationship of the video signals at point (■) is always constant.

That is, the time difference '1'1 between the rising time of the horizontal synchronizing signal HD1 and the starting time of the effective video period of the video signal is always constant.

Next, the video signal at the output of the process amplifier 111 (point ■) is l1lD,
It will be delayed for a long time. On the other hand, phase comparator 1140 input (point ■
) is also delayed by #) Ta2 due to the propagation delay in the cable 118, but numerically the propagation delay time of the cable 118 using a single wire or twisted pair wire is the same as the propagation delay time of the coaxial cable 119. Furthermore, since TDI also includes the delay time in the process amplifier 111, there is a relationship of TD2<TDI. Further, the phase of the horizontal synchronizing signal HD2 at the input of the phase comparator 114 (point ■) completely matches the phase of the horizontal synchronizing signal HDI' at the point ■ due to the action of the phase comparator 1140. Therefore, the time difference T2 between the video signal and the horizontal synchronization signal HD2 at point ■ is T22Ill1
+r1+D1111D2, and if the values of l1ll and T2 are large and far apart, the process amplifier 11
A failure occurs in signal processing in 1. For example, when the process amplifier 111 optically clamps the video signal in FIG. 4, the optical black clamp pulse 0BCP corresponds to the optical black period T of the video signal. P
Since it does not match T and also spans the effective video period, the pedestal level of the video signal fluctuates depending on the amount of incident light.
Operation becomes extremely unstable.

Conventionally, a method using a multiphase adjuster is widely known as a method for preventing circuit instability caused by the above-mentioned delay time error.

FIG. 5 is a block diagram showing a second conventional television imaging device.

As shown in FIG. 5, a phase adjuster 120 is inserted into the input section of the phase comparator 114 to delay the horizontal synchronizing signal HD1' from the synchronizing signal generating circuit 104.

In FIG. 5, the same numbers as in FIG. 3 indicate the same components.

FIG. 6 is a time chart showing the operation of the second conventional example.

The time chart shown in FIG. 6 shows waveforms of various parts in one horizontal scanning period.

In FIG. 6, there is a time difference T1 between the horizontal synchronization signal HD1' at point ■ and the video signal at point ■, and the video signal at point Depending on the influence ■
The horizontal synchronizing signal H1)l' at point ■ is also delayed by TD2 compared to point ■ due to the propagation delay in the cable 118, and the horizontal synchronizing signal HD20 at point ■ The phase is determined by the phase comparator 114
This is the same as the first conventional example shown in FIG. 3 in that the phase of the horizontal synchronizing signal H1)1' at point (2) completely matches that of the above due to the action of (2). What is characteristic here is that the horizontal synchronizing signal MDI' is input to the phase comparator 114 after being delayed by #) TD3 by the phase adjuster 120.

According to this phase relationship, the time difference T3 between the video signal at point ■ and the horizontal synchronization signal HD2 is 'L'3=
It is expressed as Tt +TDI TD2 TD3. Therefore, the delay time TD3 in the phase adjuster 120 is TD3=TD
If ITD2 is selected properly, the time difference T3 and the time difference Tl will be equal. This means that by appropriately selecting the delay time TD3 of the phase adjuster 120, the propagation delay time error in the camera cable 116 and the delay time in the process amplifier 111 can be corrected.

[Problem that the invention attempts to solve]

In the conventional television imaging device described above, each time the length of the camera cable is changed, an error occurs between the propagation delay time in a single wire or twisted pair wire and the propagation delay time in a coaxial cable. The phase adjuster must be readjusted so that the time error is corrected,
There are disadvantages in that the operation of the apparatus is very complicated, and furthermore, if the delay time of the process amplifier changes due to temperature changes, changes over time, etc., the phase adjuster must be readjusted as well.

The present invention eliminates the above-mentioned conventional drawbacks, and its purpose is to provide a television imaging device that automatically corrects delay time errors in video signals in camera cables and process amplifiers.

[Means for solving the problem]

The television imaging device of the present invention includes a camera head section, a camera control unit, and a camera cable that connects these. an oscillator, a first synchronization signal generation circuit which is supplied with an output from the voltage controlled oscillator and generates a predetermined group of pulses, and a first horizontal synchronization signal generation circuit from the first synchronization signal generation circuit that is applied to the video signal from the imaging device. a second synchronization signal generation circuit, which includes at least a synchronization signal generation circuit that mixes synchronization signals, and a second synchronization signal generation circuit that is supplied with an output from an oscillator different from the voltage controlled oscillator to the camera control unit and generates a predetermined group of pulses; a synchronization signal separation port for separating the first horizontal synchronization signal mixed into the video signal propagated through the camera cable; and generation of the separated first horizontal synchronization signal and the second synchronization signal. a phase comparator that compares the phases of a second horizontal synchronization signal from the circuit and generates a control voltage according to a phase error, and the voltage controlled oscillator is controlled by the control voltage from the phase comparator. It is characterized by

[Effect]

The camera head is equipped with a horizontal synchronization signal addition circuit, the camera control unit is equipped with a synchronization signal separation circuit, and the time difference between the video signal and the horizontal synchronization signal generated on the camera control unit side and the video signal and effective video period start signal are provided. This eliminates the need for phase adjustment even if the length of the camera cable is changed, and also automatically corrects delay time errors in process amplifiers and the like. Furthermore, the number of cores in the camera cable can be reduced compared to conventional models.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a time chart showing the operation of the embodiment shown in FIG.

In FIGS. 1 and 2, the same numbers as in FIGS. 3 and 4 indicate the same components.

In FIG. 1, the television imaging device of this embodiment is as follows:
In addition to the first conventional example shown in FIG.
an addition circuit 1 for mixing the horizontal synchronization signal HD1 from the synchronization signal generation circuit 104 with the video signal from the composite video signal, and a synchronization signal separation circuit 2 for separating the horizontal synchronization signal HD1 mixed into the composite video signal. It is composed of

FIG. 2 shows waveforms of various parts during one horizontal scanning period of this embodiment.

Next, the operation of the television imaging apparatus of this embodiment will be explained using FIG. 1 and FIG. 2 together.

First, the CCD imaging device 102 is connected to the synchronization signal generation circuit 1.
Because it is driven accurately in synchronization with the pulse group from 04,
The phase relationship between the horizontal synchronizing signal HDI at the output of the synchronizing signal generating circuit 104 (point ■) and the video signal at the output of the preamplifier 106 (point ■) is always kept constant. Here, to simplify the explanation, it is assumed that the time difference between the rising 9 time of the horizontal synchronizing signal HDI and the effective video period start time of the video signal is T4. The adder circuit 1 mixes the horizontal synchronizing signal HD1 with the video signal to create a composite video signal (point ■). This composite video signal is sent to the buffer amplifier 107.
and camera control unit 11 via coaxial cable 119
However, the propagation delay time in the coaxial cable 119 and the buffer amplifier 107 and process amplifier 111
Due to the influence of the delay time at , point [phase] is delayed by TD4 compared to point . What should be noted here is that
The delay time for the horizontal synchronizing signal HDI included in the composite video signal and the delay time for the video signal also included in the composite video signal are completely equal and exactly match TD4 because they pass through the same propagation path. The point is that

Next, the synchronization signal separation circuit 2 separates the horizontal synchronization signal HDI mixed into the composite video signal and sends it to the phase comparator 114.
(point 0). Further, the other input terminal of the phase comparator 114 is connected to the synchronizing signal generating circuit 11.
Horizontal synchronization signal HD2 from 0 is supplied (point 0)
. Here, both HDl and HD2 are controlled so that their phases completely match by the action of a phase-locked loop consisting of a phase comparator 114, a voltage side control oscillator 103, and a synchronization signal generation circuit 104. Therefore, the time difference between the video signal and the horizontal synchronization signal HD2 at the point [phase] is always equal to the above-mentioned time difference T4, and the process amplifier 11
1 allows signal processing such as optical plaque clamping to be performed with high precision.

Furthermore, even if the length of the camera cable 116 is changed, the amount of delay l
Since only 1lD4 changes and other phase relationships remain constant, the television imaging apparatus of this embodiment can be operated without adjustment.

In the embodiments of the present invention, a television imaging apparatus using a solid-state imaging device (COD) as an imaging device has been described as an example, but the present invention is also applicable to a television imaging apparatus using an image pickup tube.

〔Effect of the invention〕

As explained above, the present invention has a horizontal synchronization signal addition circuit in the camera head section and a synchronization signal separation circuit in the camera control unit to detect the time difference between the video signal and the horizontal synchronization signal generated on the camera control unit side. By making the time difference equal to the time difference between the signal and the start time of the effective video period, it is possible to automatically correct the delay time error of the video signal due to the camera cable or the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart showing the operation of the embodiment shown in FIG. 1, and FIG. 3 is a first conventional separate type television imaging device. FIG. 4 is a time chart showing the operation of the first conventional example, FIG. 5 is a block diagram showing the second conventional television imaging device, and FIG. 6 is the operation of the second conventional example. It is a time chart showing. 1, 112... Addition circuit, 2... Synchronization signal separation circuit, 101... Lens, 102... CCD imaging device, 103... Voltage controlled oscillator, 104... Synchronization signal generation circuit, 105 ...COD driver, 106・
...Preamplifier, 107,113...Buffer amplifier, 109...Oscillator, 110...Synchronization signal generation circuit, 111...Process amplifier, 114...Phase comparator, 117,118...Single wire Or twisted pair wire cable, 119... coaxial cable, 120...
Phase adjuster, 108...Camera head section, 115...
-Camera control unit, 116...camera cable. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] In a television imaging device consisting of a camera head section, a camera control unit, and a camera cable connecting these, the camera head section includes a voltage controlled oscillator whose oscillation frequency changes depending on a predetermined control voltage, and a a first synchronization signal generation circuit to which an output is supplied and generates a predetermined group of pulses; and a synchronization signal mixing circuit that mixes a first horizontal synchronization signal from the first synchronization signal generation circuit with a video signal from an imaging device. comprising at least
The camera control unit also includes a second synchronizing signal generating circuit that is supplied with an output from an oscillator different from the voltage controlled oscillator and generates a predetermined group of pulses, and a second synchronizing signal generating circuit that generates a predetermined group of pulses that is mixed into the video signal propagated through the camera cable. a synchronization signal separation circuit that separates the first horizontal synchronization signal, and a phase comparison between the separated first horizontal synchronization signal and a second horizontal synchronization signal from the second synchronization signal generation circuit; 1. A television imaging device comprising at least a phase comparator that generates a control voltage according to a phase error, and wherein the voltage controlled oscillator is controlled by the control voltage from the phase comparator.