JPS6292680A - Television camera unit - Google Patents

Abstract

PURPOSE:To prevent lag of timing of signal processing by providing a means that waveform shapes pulselike video signals from a solid-state image pickup element and a means that delays output signals of the waveform shaping means by a specified time and processing the video signals on the basis of timing of output signals of the delaying means. CONSTITUTION:Video signals passed through a pre-amplifier 12 are made to signals of negative polarity as shown in the figure (a). The signals are amplified further to negative saturation level by an amplifier 20 and supplied to a Schmitt trigger circuit 20. The Schmitt trigger circuit 22 waveform shapes input signals and outputs square wave shown in the figure (b). Timing of the negative peak is delayed from timing of fall of output pulse of the Schmitt trigger circuit 22 by specified time at all times. Therefore, by delaying output signals of the Schmitt trigger circuit 22 by a specified time, timing of the negative peak can be obtained. Thereby, lag of timing of signal processing due to delay of video signals during transmission from a solid-state image pickup element 10 to a video signal processing circuit can be prevented by simple constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a television camera device, and particularly to a charge coupled device (CCD). The present invention relates to a television camera device in which a camera having a built-in solid-state image sensor is provided with a separate video processing circuit and a video processing circuit.

[Conventional technology]

In recent years, with the development of solid-state image sensors, CCDs have been installed at the tip of endoscopes.
Endoscopic devices have been developed that incorporate a solid-state imaging device such as 1 to image the inside of a body cavity, display the image inside the body cavity on a monitor device, and perform a diagnosis while viewing the displayed image. In this case, a video processing circuit is provided outside the endoscope, and video signals from the COD are transmitted to the video processing circuit through the endoscope. Generally, the video signal output from the COD is a discrete pulse-like signal, so it is sampled and held in a video processing circuit and converted into a continuous video signal.

[Problem that the invention seeks to solve]

Here, the video signal is delayed to some extent during transmission within the endoscope. When the length of the endoscope is short, the delay time has almost no effect, but when the length of the endoscope is long, the delay time is 1! The impact of extended time cannot be ignored.

For example, the sampling timing of the sample/hold circuit in the #image processing circuit is determined in synchronization with the drive pulse of the CDD, so it is constant regardless of the length of the endoscope. Therefore, if the video signal is extended by 'M and input to the video processing circuit, the sampling timing may be shifted and the video signal may not be correctly converted into a continuous signal.

Furthermore, this delay time differs depending on the endoscope, so if the type (length) of endoscopes connected to the same image processing circuit changes, this delay time will differ depending on the type of endoscope. There is a problem that adjustment of sampling timing becomes complicated.

This delay affects not only the sampling timing of the sample/hold circuit, but also the timing control of various signal processing! give. Further, this problem of delay during transmission is not limited to the above-mentioned endoscope apparatus, but applies to all television camera apparatuses in which the camera head and the video/processing circuit are separate units.

This invention was made with attention to such problems, and in a television camera device in which a camera head having a solid-state image sensor and a video processing circuit are separately provided, the transmission from the solid-state image sensor to the video processing circuit is The purpose of this is to prevent deviations in signal processing timing due to delays in video signals during processing.

[Means and operations for solving the problems] The television camera device according to the present invention includes means for waveform shaping a pulsed video signal from a solid-state image sensor and means for delaying the output signal of the waveform shaping means for a predetermined period of time. The video signal from the solid-state image sensor is processed based on the timing of the output signal of the delay means.

〔Example〕

An embodiment of a television camera device according to the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of this embodiment applied to an endoscope device.
is built-in.

A video signal from the CCD 10 is transmitted to an external video processing circuit through the endoscope. The video processing circuit is C in Figure 1.
This is the part other than CD l O. The video signal is first input to the preamplifier 12. The output of preamplifier 12 is provided via sample/hold circuit 14 to process circuit 16 and via amplifier 20 to Schmitt trigger circuit 22. A CCD driver 18 is also provided within the video processing circuit, and drive pulses from the CCD driver 18 are supplied to the CCD 10. Schmidt
The output of the trigger circuit 22 is transmitted to the delay circuit 24. The signal is supplied as a sample pulse to the sample/hold circuit 14 via the pulse shaping circuit 26.

Sample/hold circuit 14 includes a capacitor 32 connected to preamplifier 12 via analog switch 30;
It consists of a transistor 34 and a resistor 36 that supply the discharge current of the capacitor 32 to the next stage process circuit 16. A sampling pulse output from the pulse shaping circuit 26 is supplied to the control end of the analog switch 30.

The amplifier 20 has a differential amplifier 42, and the output of the first amplifier 12 is inputted to the manual input terminal of the differential amplifier 42 via a capacitor 38. The output signal of the differential amplifier 42 is supplied to one input terminal of the differential amplifier 42 via a feedback resistor 44 .

A manual input terminal of the differential amplifier 42 is grounded via a resistor 40, and a negative input terminal is grounded via a resistor 46.

The operation of this embodiment will be explained with reference to FIG. The video signal that has passed through the preamplifier 12 is a negative polarity signal as shown in FIG. 2(a). In this embodiment, the video signal is on a 7.16 MHz carrier wave signal. This signal is further amplified to a negative saturation level by an amplifier 20,
The signal is supplied to the Schmidt trigger circuit 22. The Schmitt trigger circuit 22 waveform-shapes the input signal as shown in FIG.
A rectangular wave as shown in b) is output.

The sample/hold circuit 14 preferably samples/holds the video signal at the timing of its negative peak. As is clear from FIG. There is always a predetermined time delay from the downlink timing. Therefore,
The timing of this negative peak can be obtained by Schmidt-Trial delaying the output signal of circuit 22 for a predetermined period of time. In this embodiment, the negative peak timing is delayed by about 35 n sea from the falling timing of the output pulse of the Schmitt trigger circuit 22. That is, the delay time of the delay circuit 24 is set to about 35 nsec. It is preferable that the sampling period of the sample/halt circuit 14 be short. Therefore, the pulse shaping circuit 26 detects the falling edge of the output pulse of the delay circuit 24 and generates a sampling pulse with a narrow pulse width as shown in FIG. 2(d). This sampling pulse is applied to the analog switch 30 in the sample/hold circuit 14. The control of m
Supplied at the end.

As described above, according to this embodiment, the video signal supplied from the solid-state image sensor at the tip of the endoscope is processed based on the timing of the signal obtained by waveform shaping the video signal and delayed by a predetermined time. This makes it possible to prevent a shift in signal processing timing due to the eight-time delay of the video signal during transmission from the solid-state image sensor to the video signal processing circuit with a simple configuration. Even if the type of signal changes, the length of the transmission path changes, and the delay time changes, the frequency of the video signal does not change, so the timing of the output pulse of the Schmitt trigger circuit 22 does not change, so the sampling timing does not shift.

Note that the sampling pulse obtained in this manner is adapted not only to the sampling timing of the sample/hold circuit described above, but also to other timings of the video processing system.For example, when digitally processing a video signal, Although an A/D converter is required, it can also be used for clock pulses during A/D conversion. All timings for the video system can be created based on this sampling pulse.

Further, oTfI is also used as a clamp pulse when a clamp circuit is provided in the amplifier 12. An example of the clamp circuit in this case is shown in FIG. 3. The video signal from CGDlo is supplied to the video processing system (sample/hold circuit 14) via the isolation transformer 66, impedance converter 683, capacitor 70, and impedance converter 74. be done. Capacitor 70 and impedance conversion r47
A dynamic clamp circuit 72 is connected between the terminals 4 and 4. The dynamic clamp circuit 72 consists of an analog switch made of bridge-connected diodes, and a self-bias transformer 76 when a pulsed bias 'If current is passed through the analog switch. The above-mentioned sampling pulse is supplied to this self-bias transformer 76, and the video signal from the CCD 1 O is clamped in accordance with this pulse.

Note that the present invention is not limited to the above-mentioned endoscope apparatus, but is applicable to all television camera apparatuses in which the camera head and the video processing circuit are separate bodies.

〔Effect of the invention〕

As explained above, according to the present invention, when signal processing a video signal transmitted from a solid-state image sensor installed remotely, a signal obtained by waveform shaping the video signal is delayed by a predetermined time. Since signal processing is performed based on timing, it is possible to prevent deviations in signal processing timing due to delays in the video signal during transmission from the solid-state imaging device to the video signal processing circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of a television camera device according to the present invention, FIGS. 2(a) to (d) are timing charts explaining the operation of this embodiment, and FIG. FIG. 7 is a circuit diagram of a clamp circuit as another application example of the invention. 10... Solid-state image sensor (CCD) 14... Sample/hold circuit 16... Process circuit 20...#! Radiator 22...Schmitt O trigger circuit 24...'M extension circuit 26...Pulse shaping circuit Applicant's agent Patent attorney Atsushi Tsuboi 2nd B3j 3rd-

Claims (1)

[Claims] In a television camera device in which a video signal from a remotely located solid-state image sensor is processed by a video processing circuit, the video processing circuit delays a pulse signal obtained by waveform-shaping the video signal from the solid-state image sensor by a predetermined period of time. A television camera device characterized in that a video signal from the solid-state image sensor is subjected to signal processing based on signal timing.