JPH0573109B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a television camera device, and more particularly to an endoscope television camera device in which a solid-state image sensor is incorporated in an endoscope insertion portion.

[Prior art] The conventional technology for such a device is disclosed in Japanese Unexamined Patent Application Publication No. 1986-
There is a built-in camera described in issue 54933. In this endoscope camera, a solid-state imaging device such as a CCD is built into the tip of the endoscope insertion section, an optical image obtained by the imaging lens is captured by the CCD, and the imaging signal is sent to an external display monitor. is displayed.

[Problems to be Solved by the Invention] In such an endoscope television camera device, since the tip of the endoscope comes into direct contact with the patient, a primary circuit installed outside the endoscope is required to prevent electric shock. (power supply,
(video process circuit, etc.) and CCD at the end of the endoscope
The specified insulation must be provided between the Currently, standards are being established for withstand voltage and leakage current between a power supply and a CCD. For example, as a power source
When AC100V is used, the withstand voltage is 4KV,
The leakage current is thought to be 10μA.

In conventional endoscopes, the optical image of the tip of the insertion tube is guided to the eyepiece via an image guide fiber and the image is captured by a TV camera attached to the eyepiece. It was sufficient to insulate the control signal and its circuit from the parts that come into contact with the human body. However, in the endoscope television camera device, the CCD installed inside the endoscope,
The scale of electronic circuits is larger than conventional circuits,
If an attempt was made to insulate these parts from the parts that come into contact with the human body using an insulating member, it was not possible to reduce the diameter of the endoscope insertion section. Also, to obtain sufficient resolution, CCD
The number of surface primes had to be sufficiently large, making it increasingly difficult to make the diameter smaller.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems. It is an object of the present invention to provide an endoscope television camera device that can achieve a smaller diameter insertion portion and a higher pixel density of an image sensor by providing means for insulating the video processing portion provided outside.

[Function] According to the present invention, by interposing the isolation means between the camera section of the endoscope and the video processing means connected thereto in an electrically insulated state, the human body The endoscope inserted into the patient can be isolated from the video processing unit, and there is no risk of current flowing into the patient. This is effective in reducing the diameter of the insertion portion and increasing the resolution of the captured image.

[Embodiment] An embodiment of the endoscopic 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 a first embodiment. An imaging lens 12 is built into the tip of the endoscope 10 , and an optical image of a subject formed by the imaging lens 12 is incident on the imaging surface of a solid-state image sensor (CCD) 14 . Inside the endoscope 10, a light guide 16 that guides illumination light emitted from an external light source device (not shown) to the distal end, and a magnifying lens 18 for illumination are also provided. After the output signal from the CCD 14 is amplified by a preamplifier 20, it is sent to a multiplier 2 via a signal line.
2. An oscillation signal from an oscillator 24 is also supplied to the multiplier 22 . The output signal of multiplier 22 is transmitted to multiplier 28 via isolation transformer 26 .

The oscillation frequency o of the oscillator 24 is set to a sufficiently higher frequency than the frequency band of the video signal of the output signal of the CCD 14. Multiplier 22 is oscillator 24
The output signal from the CCD 14 is subjected to AM modulation (carrier suppression modulation) using the signal from the CCD 14 as a carrier wave signal. Therefore, as shown by waveform A in FIG. 2, the frequency band of the output signal of the multiplier 22 is
The sideband is centered around the oscillation frequency o. In addition, in FIG. 2, waveform B is the output signal of the CCD 14, and the broken line is the output signal of the isolation transformer 26.
is the passband of Since the fractional bandwidth (=bandwidth/center frequency) of the output signal of the multiplier 22 is small, the isolation transformer 26 passes the output signal of the multiplier 22 without distortion.

The signal passed through the isolation transformer 26 is multiplied by the output signal o of the oscillator 30 having the same frequency as the carrier signal by a multiplier 28 and demodulated. Therefore, from the multiplier 28, the CCD 14
The same signal that was output from is output. Here, if the modulation is normal AM modulation, the demodulation side multiplier 28 and oscillator 30 are replaced with an AM detector. The oscillators 24 and 30 are constructed with accurate oscillators such as crystal oscillators, and are constructed so that there is no deviation in the number of oscillation wavelengths to prevent beats from occurring.

The output signal of the multiplier 28 (same as the output signal of the CCD 14) is subjected to processing required for a television signal in a video processing circuit 32, and is displayed on a CRT monitor 34.

According to the first embodiment, the output signal from the CCD 14 is subjected to AM modulation using a carrier signal whose frequency is sufficiently higher than that of the video signal component therein, so that the signal has a high center frequency and a small fractional bandwidth. Thereafter, this signal is transmitted to the video processing circuit 32 and CRT monitor 34 via the isolation transformer 26. Therefore, by using the inexpensive isolation transformer 26, the tip of the endoscope that may come into contact with the human body can be reliably electrically isolated from the power source, and the withstand voltage and leakage current values can be kept within safe ranges.

Note that isolation can also be implemented within the video processing circuit 32 as an isolation location for safety. However, in that case, for example, if you try to isolate the digital signal after A/D conversion, the A/D
If the D converter has an 8-bit output, it is necessary to isolate eight signal lines. Furthermore, even if isolation is performed in the analog section in front of the A/D converter, it is necessary to isolate the clamp signal and sample-hold pulse signal for correlated double sampling, etc. The number of signal lines increases. Further, when isolation is performed within the video process circuit 32, the scale of the circuit that is electrically connected to the human body increases. Therefore, it becomes difficult to achieve spatial isolation from the housing exterior and the like. Therefore, it is desirable to keep the scale of the circuit electrically connected to the human body as small as possible.

As in this embodiment, an isolation transformer 26 is installed between the CCD 14 and the video processing circuit 32.
By connecting these, the circuit scale can be reduced.

Next, another embodiment of the invention will be described. In the following drawings, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 3 shows a modification of the first embodiment. In the first embodiment, the demodulation oscillator 3
0 is provided separately from the modulation oscillator 24, but in this modification, the demodulation oscillator is not provided and the carrier wave signal o used for modulation is transmitted to the demodulation side. The output signal o of the oscillator 24 is supplied via an isolation transformer 40 and an amplifier 42 to a multiplier 28 for demodulation. Here, the pass band of the isolation transformer 40 is the same as that of the isolation transformer 26.
Unlike that, the frequency o of the carrier signal may be the same, or there may be some band around o. According to this modification, the frequency of the demodulation signal accurately matches the frequency of the carrier signal, so no beat occurs during demodulation.

FIG. 4 is a block diagram of a second embodiment of the invention. The output of preamplifier 20 is supplied to multiplier 22 via adder 50. The output signal from the CDD 14 is provided with a period (dark reference period) in which there is no signal for several pixels for each line. By inputting a pulse signal synchronized with this dark reference period from the input terminal 48 to the adder 50, the pulse signal is inserted into the dark reference period of the output signal of the CCD 14. 5a and 5b show the waveforms of the input signal and output signal of the adder 50. The burst signal from the oscillator 51 is superimposed on the output of the adder 50 in the multiplier 22, and the signal as shown in FIG.
It is transmitted to the second side. Isolation transformer 2
6 is input to the multiplier 28 and is also input to the PLL circuit 54 via the gate 52. The gate 52 allows only the signal during the dark reference period to pass through, as the output signal waveform is shown in FIG. 5d. As a result, PLL circuit 5
4 uses a phase comparator 56, LPF 58, and VCO 60 to generate a continuous signal that is in phase with the burst signal. This continuous signal is supplied to a multiplier 28, and the modulated signal that has passed through the isolation transformer 26 is demodulated.

Also in the second embodiment, since the carrier wave signal for modulation is supplied to the demodulation side via the isolation transformer 26, no beat occurs during demodulation. Furthermore, since the carrier wave signal for modulation is also transmitted through the same isolation transformer 26 as the video signal, there is no need to provide a dedicated isolation transformer for carrier wave transmission as in the above-mentioned modification, and the configuration can be simplified. It's easy.

In the above embodiment, the signal is AM modulated when passing through the isolation transformer, but FM modulation may be performed instead.

In addition, in the above-described embodiment, the signal from the CCD 14 may be taken out via the S/H circuit and the LPF.

[Effects of the Invention] According to the invention as explained above, it is possible to electrically isolate the camera section that comes into contact with the human body and the external power supply section at low cost and reliably, and the withstand voltage of the connection between the camera section and the power supply section can be reduced. An endoscopic television camera device is provided that can keep the leakage current value within a safe range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an endoscope television camera device according to the present invention, FIG. 2 is a diagram showing the pass band of an isolation transformer for explaining its operation, and FIG. 4 is a block diagram of a modification of the first embodiment, and FIG. 4 is a block diagram of a modification of the first embodiment.
A block diagram of the embodiment, and FIGS. 5a to 5d are signal waveform diagrams for explaining the operation of the second embodiment. 10...Endoscope, 14...CCD, 22,28
... Multiplier, 24, 30 ... Oscillator, 26 ... Isolation transformer, 32 ... Video process circuit, 34 ... CRT monitor.

Claims (1)

[Scope of Claims] 1. An endoscope camera section that is provided inside the endoscope insertion section and that captures endoscopic images and outputs electrical signals; and an endoscope camera section that is provided outside the endoscope from the endoscope camera section. a video processing means for processing an output video signal; and a video processing means connected between the endoscope camera section and the video processing means, the endoscope camera section and the video processing means being electrically insulated. an isolation means for connecting, the isolation means modulating the video signal output from the endoscope camera section using a carrier wave signal having a higher frequency than the frequency of the video signal; An endoscope television camera device comprising an isolation transformer section having a predetermined pass band centered on the frequency of the carrier wave signal and passing the modulated video signal output from the modulating means. .