JPH0796008B2 - Electronic endoscopic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electronic endoscope apparatus having a matching means provided between an image pickup means and a drive means.

[Prior Art] In recent years, an electronic endoscope has been proposed in which a solid-state imaging device such as a CCD is arranged on the distal end side of an elongated insertion portion.

FIG. 9 shows a schematic configuration of a conventional example of the electronic endoscope.

An objective lens 3 for image formation and a CCD 4 disposed on the focal plane of the electronic endoscope 1 and the insertion portion 2 are built in the front end portion thereof, and an image of a subject 5 is formed on the CCD 4 by the objective lens 3. Be done.

A drive signal is applied to the CCD 4 from a drive signal generation circuit 7 via a signal cable 6. By applying this drive signal, the signal read from the CCD 4 passes through the signal cable 8 and
It is input to the video signal processing circuit 9 and a predetermined video signal is generated.

By the way, in the above-mentioned conventional example, the drive signal generating circuit 7 causes the CC
The drive signal applied to D4 was not an optimum waveform for CCD4 due to reflections due to mismatch at both ends of cable 6 and attenuation during cable transmission, and a good image was not obtained.

In order to solve such drawbacks, the present applicant has filed Japanese Patent Application No. Sho 62-18.
In 5160 (Japanese Patent Laid-Open No. 64-2622), one solution is proposed. That is, as shown in FIG. 10, CCD4
The terminating resistance equal to the characteristic impedance of the cable 6 on the side
By providing 10, the influence of reflection is improved.

[Problems to be Solved by the Invention] However, the terminating resistor 10 provided close to the CCD 4 generates a large amount of heat, which causes the temperature of the CCD 4 to rise in particular. There is room for improvement because it will lead to deterioration.

Further, the applicant of the present invention has filed Japanese Patent Application No. 62-186334 (Japanese Patent Application Laid-Open No. 1-29334).
No. 247) proposed another solution.

That is, the waveform of the drive signal is corrected by superimposing the edge enhancement pulse on the reference square wave pulse. However, while this means is effective in compensating for attenuation during cable transmission, it is less effective in reflection due to mismatch at the termination. This is because when driving with a square wave as shown in FIG. 11A, a reflected wave as shown in FIG.
At the CCD drive signal input end, the drive signal waveform as shown in FIG.

Here, the time t1 is the time required for the signal to travel back and forth through the cable. Further, FIG. 11 (b) has a negative polarity with respect to FIG. 11 (a) because, when the signal of (a) is reflected on the CCD side, the drive circuit side compares with the characteristic impedance of the cable. If it is small, the polarity is inverted and reflected on the drive circuit side, and transmitted again to the CCD side.

Further, this solving means requires a correction circuit for edge enhancement, which causes a problem that the circuit scale of the drive signal generation circuit is increased and the cost is increased.

The present invention has been made in view of the above-mentioned points, and a drive signal can be applied to the solid-state image sensor without reflection, and the solid-state image sensor does not generate heat.
It is an object of the present invention to provide an electronic endoscope device that can obtain good image quality.

[Means and Actions for Solving Problems] In the present invention, a terminal for applying a drive signal to the solid-state image sensor,
By providing the matching means away from the solid-state image sensor via the cable, it is possible to apply a drive signal without generating a reflected wave to the solid-state image sensor and to eliminate heat generation to obtain a good image. I have to.

EXAMPLES The present invention will be specifically described below with reference to the drawings.

1 to 4 relate to a first embodiment of the present invention.
FIG. 1 shows the electronic endoscope apparatus of the first embodiment, FIG. 2 shows the image pickup means on the distal end side of the electronic endoscope, FIG. 3 shows an example of laying a noise canceling cable, and FIG. The waveform for operation | movement description of 1st Example is shown.

As shown in FIG. 1, an electronic endoscope apparatus 11 of the first embodiment supplies an electronic endoscope (hereinafter abbreviated as an electronic scope) 12 having a built-in image pickup means and illumination light to the electronic scope 12. A video processor 15 having a built-in light source unit 13 and a signal processing unit 14 for performing signal processing on the electronic scope 12, and a monitor 16 for displaying the video signal processed by the signal processing unit 14 as an image. It

The electronic scope 12 has an elongated insertion portion 17, a light guide 18 for transmitting illumination light is inserted into the insertion portion 17, and by connecting the incident end of the light guide 18 to the light source portion 13. , Illumination light is supplied. This light source unit 13 is
White light emitted from the lamp 21 is red (R), green (G),
After being converted into R, G, B color sequential light by passing through a rotary filter 22 provided with a color transmission filter of three primary colors of blue (B), the light is condensed by a condenser lens 23, It is supplied to the incident end face as illumination light. The rotary filter 22 is rotated by a motor 24.

The R, G, and B illumination light transmitted by the light guide 18 is emitted toward the subject 25 from the emission end face. The light reflected by the subject 25 is collected by the objective lens 26 attached to the distal end of the insertion portion 17, and is placed on the focal plane of the CC.
A subject image is formed on the imaging surface of D27. The CCD 27 photoelectrically converts this image and accumulates it as a signal charge.

The CCD 27 has a power supply line 31 and a ground line 32, which are connected to a power supply terminal VDD and a grounding terminal SUB on the video processor 15 side, respectively.
The power from the power supply 33 is supplied via the.

Further, the horizontal transfer clock φs generated from the drive signal generation circuit 34 is changed in voltage level by the driver 35, further shaped by the matching circuit 36 constituted by the capacitor C and the resistor R, and then the horizontal transfer clock transmission cable ( Hereafter, it is transmitted to the CCD 27 via a φ _S transmission cable 37).

In this case, the horizontal transfer clock φ transmitted to the CCD 27
_S is returned to the φ _S matching resistor (terminating resistor) 39 connected to the other end on the video processor 15 side via the φ _S terminal of the CCD 27 or a φ _S matching cable 38 whose one end is connected near this pin. , this phi _S matching resistor 39, it is a feature of this first embodiment that is to take the cable 38 and matching.

Here, since the input capacity of the input terminal of the horizontal transfer clock φ _S of the CCD 27 is small, even if the CCD input terminal is connected as a load between the φ _S transmission cable 37 and the φ _S matching cable 38, it is almost impossible to match. It has no effect.

By the way, the drive signal generation circuit 34 also generates a vertical transfer clock φ _P , and the voltage level of this clock φ _P is changed by the driver 41.
After the waveform is shaped through the matching circuit 42 constituted by and, the vertical transfer clock transmission cable (hereinafter φ _P
It is transmitted to the CCD 27 via a transmission cable (abbreviated as 43).
Here φ matching cables to _P transmission cable 43,
The matching resistor is not provided because its frequency is significantly lower than that of the horizontal transfer clock φ _S, and thus it is not affected by the matching mismatch.

As shown in FIG. 2, the optical information formed on the CCD 27 is photoelectrically converted and stored in each pixel 45 as electric charge. The accumulated charges are applied to the vertical transfer clock φ _P and are transferred in the vertical direction by the amount of the clock, and are transferred to the two horizontal transfer registers 46 and 47. Then, the charges in the horizontal transfer registers 46 and 47 are transferred in the horizontal direction by the application of the horizontal transfer clock φ _S , and are output to the output buffers 48 and 49 as video signals, respectively.

The video signals current-amplified by the output buffers 48, 49 are output to the transmission cables 53, 54 via the matching resistors 51, 52, respectively.

Video signals transmitted through the transmission cables 53, 54 V _OUT1 , V _OUT2
Is applied to the non-inverting input terminals of the differential amplifier circuits 55 and 56.
Here, one end of one noise canceling cable 57 is connected to the inverting input ends of the differential amplifier circuits 55 and 56. The other end of the noise canceling cable 57 has a resistor 5 having the same resistance value as the matching resistors 51 and 52 provided near the CCD 27.
Grounded through 8.

The noise on the video signals in the two transmission cables 53 and 54 also propagates to the cable 57, so that the differential amplifier circuit
It can be eliminated by obtaining differential outputs at 55 and 56 respectively. This is particularly effective in removing noise when using an electric knife.

In the past, one noise canceling cable was provided for each of the transmission cables 53, 54, but this increases the number of cables in the electronic scope, so
In the first embodiment, as described above, the number is reduced to one, and the effect of reducing the outer diameter of the electronic scope 12 is produced.

By the way, the cables 53, 54, 57 in the electronic scope 12
As shown in FIG. 3 (a), the cable can be arranged spirally around the parallel cables 53, 54, or as shown in FIG. 3 (b), the cable can be flat. In the case of a cable, a cable 57 is placed between the cables 53 and 54.
It has a structure in which is arranged.

In addition to these, a structure in which the cables 53, 54, 57 are braided in three may be used.

Of the video signals from which noise has been removed by the differential amplifier circuits 55 and 56, the output of one circuit 55 is the half pixel delay circuit 58.
Is delayed by one half of one pixel period, added by the adding circuit 59, and then input to the video signal processing circuit 60. Each waveform at this time is shown in FIG.

That is, by application of the vertical transfer clock φ _P , only one pixel is vertically transferred, and one line of pixels in the bottom row is transferred to the two horizontal transfer registers 46 and 47. When the horizontal transfer clock φ _S is applied subsequently to the vertical transfer clock φ _P as shown in FIG. 4B, the two horizontal transfer registers 46 and 47 synchronize with the horizontal transfer clock φ _S. Then, as shown in (c) and (d) of the figure, the video signals V _OUT1 and V _{OUT2 for} one pixel are output from the respective registers 46 and 47. One of the above video signals V _OUT1 is a half pixel delay circuit 5
Since the signal is output after being delayed by a half cycle of the horizontal transfer clock φ _S by 8, the signal added by the adder circuit 59 has a signal waveform V _A as shown in FIG. 4 (e), which corresponds to the subject image. Become a signal.

In the video signal processing circuit 60, gamma correction, clamp, RGB3
A standard video signal is generated by processing such as synchronization of primary color information and edge enhancement, and is output to the monitor 16. The monitor 16 displays the captured image in color by the CCD 27.

According to the first embodiment, the φ _S transmission cable 37 for transmitting the horizontal transfer clock φ _S is connected to the φ _S matching cable 38 having a characteristic impedance equal to that of the φ _S signal cable 37 at or near the CCD 27 side terminal. and, it is connected to the phi _S matching resistor 39 at the other end of the video processor 15 side of the phi _S matching cable 38. Therefore, the horizontal transfer clock φ _S can be applied to the CCD 27 without generating a reflected wave. In this matching, φ _S matching resistor
Since the 39 is provided on the video processor 15 side, the CCD 27 does not generate heat. Therefore, in the first embodiment, an image with good image quality can be obtained.

FIG. 5 shows a second embodiment of the present invention.

The second embodiment performs a correlated double sampling (hereinafter abbreviated as CDS) processing, and is provided with a timing adjusting means for this CDS processing. That is, a major feature is that various timings for CDS are performed based on the signal φ _S returned to the matching resistor 39 by reciprocating in the electronic scope 12. Generally, when a CCD having a feedthrough output is used, the field through period in the video signal is sampled / held (hereinafter abbreviated as S / H1), and the signal charge period is sampled / held (hereinafter abbreviated as S / H2). ), And by taking out the difference, so-called CDS that removes reset noise and 1 / f noise is adopted. In this method, it is necessary to accurately match the timings of the video signal and S / H1 and S / H2. In particular, since there are various scope lengths such as the electronic scope 12, there are various types in which the time when the video signal propagates through the cable is different, and according to that there is Chiichi S / H1, S / H2
Switching the timing of is a troublesome task.

The second embodiment is to solve the above problem. Original words, by the following configuration, by cable length is changed, changes the propagation time of the video signal, for also varying propagation time it with and phi _S return signal, the return signal that phi _S By producing various signals of S / H1 and S / H2, the CDS processing can be performed with high accuracy.

The configuration and operation of the electronic endoscope apparatus 61 of the second embodiment will be described below. The description of the same parts as those in the first embodiment will be omitted.

For the CCD 27 'having the feedthrough, it is necessary to newly supply the reset signal φ _R to the CCD 27'. This reset signal φ _R is supplied from the drive signal generating circuit 34 ′ to the φ _R drive circuit as in the horizontal transfer clock φ _S of the first embodiment.
62, φ _R matching circuit 63, is applied to the CCD 27 ′ via a φ _R transmission cable 64 inserted through the electronic scope 12 ′, and one end is connected to the reset terminal of this CCD 27 ′ or a cable 64 near it. Then, it is returned via the φ _R matching cable 65 and terminated by the φ _R matching resistor 66 provided in the signal processing unit 14 ′ of the video processor 15 ′.

The signal φ _S terminated by the φ _S matching resistor 39
Is input to the CDS sample / hold signal generation circuit 67. The CDS sample / hold signal generation circuit 67 generates signals S / H1 and S / H2 with reference to the signal φ _S at the timing shown in FIG. 6, and supplies them to the first CDS circuit 68 and the second CDS circuit 69.

In the FIG. 6 is an output horizontal transfer cloak phi _S shown in FIG. Following the vertical transfer clock phi _P shown in (a) (b), the reset pulse phi _R shown in (c) with the clock phi _S is Is output. The application of these drive signals, CCD 27 'sixth diagram (d), is output signal V _OUT1, V _OUT2 such (e), the this case the reset period T _R,
The waveform has a feed through period Tf and a charge detection period T _C.

By the way, with reference to the pulse returned through the φ _S matching cable 38, the sample / hold signal generation circuit 67 operates as shown in FIGS. 6 (f) and 6 (g) to indicate the feedthrough period Tf and the charge detection period. At T _C , S / H1 and S / H2 are output and supplied to the first and second CDS circuits 68 and 69.

Therefore, even if the scope length of the electronic scope 12 changes _variously , the phase difference between the CCD output signals V _OUT1 and V _OUT2 and the pulse returned from the φ _S matching cable 38 is always constant. S / H2 can be produced accurately. By this supply, each of these periods is sampled / held, the difference signal component is extracted, and one is added by the adder circuit 59 through the half-pixel delay circuit 58 to generate the signal V _A shown in FIG. 6 (h). To be done.

According to the second embodiment, even when the scope length, that is, the lengths of the video signal transmission cables 53 and 54 are different as in the electronic scope 12 ', the CDS processing can be accurately performed, and the good image quality can be obtained. The video signal of can be obtained.

FIG. 7 shows the main part of the third embodiment of the present invention.

In the first and second embodiments, phi _S is provided with the matching resistor 39 to the video processor 15, 15 'in the operation unit 72 to the phi _S matching resistor of the electronic scope 71 in the third embodiment
39 are provided.

According to this embodiment, the number of cables in the universal cord 73 of the electronic scope 71 is reduced, and the electronic scope
The number of pins of the connector 75 connecting the 71 and the video processor 74 can be reduced.

In this figure, the light guide in the electronic scope 71 is omitted, and the light source unit in the video processor 74 is omitted. Further, the drive signal generating circuit 76 may be that shown in FIG. 1 or may be the one without the matching circuits 36, 42 and the like. Further, the video signal processing circuit 77 has a first
As shown in the figure, the differential amplifier circuits 55, 56 and the like may be provided on the front side thereof.

FIG. 8 shows a schematic structure of a main part of the fourth embodiment of the present invention.

In the fourth embodiment, the φ _S matching resistor is provided in the connector 75.
39 are provided.

The effect of this embodiment is that the operating portion can be made smaller than in the third embodiment. In addition, as in the third embodiment, the connector 75
The number of pins can be reduced.

In each of the above embodiments, a resistor is used as the matching means, but the present invention is not limited to this. For example, matching means (terminating means) or a resistor using a coil and a capacitor in parallel or in series with the resistor, A matching means (terminating means) combining two or more of a coil and a capacitor may be used. For example, it is possible to terminate with a resistor and a coil and match the impedance with the fundamental wave so that noises at other frequencies (for example, at lower frequencies, the impedance is reduced to reduce noise from electric knife).

The termination means such as a matching resistor may be different from those in the above-described embodiments as long as it is located at a position distant from the solid-state image sensor.

Further, the present invention is not limited to an electronic scope in which an image pickup means such as a solid-state image pickup element is provided on the distal end side of the insertion portion, and can be applied to an optical scope in which a television camera having a built-in image pickup means is attached to the eyepiece. .

[Effects of the Invention] As described above, according to the present invention, in addition to a drive signal transmission cable for driving a solid-state image pickup device, a matching resistor or the like is provided at a place apart from the solid-state image pickup device via another cable. Since the matching means is adapted to match at the end portion on the solid-state image sensor side, a drive signal can be applied to the solid-state image sensor without generating a reflected wave or the like.
It is also possible to solve the problem of causing the solid-state image sensor to generate heat.

[Brief description of drawings]

1 to 4 relate to a first embodiment of the present invention.
FIG. 1 is a block diagram of the electronic endoscope apparatus of the first embodiment, FIG. 2 is a block diagram showing the electric system of the image pickup means provided on the distal end side of the electronic scope, and FIG. 3 is an example of the arrangement of noise canceling cables. 4 is a waveform diagram for explaining the operation of the first embodiment,
FIG. 5 is a block diagram showing the second embodiment of the present invention, FIG. 6 is a waveform diagram for explaining the operation of the second embodiment, and FIG. 7 is a schematic block diagram of the main part of the third embodiment of the present invention. FIG. 8 is a schematic configuration diagram of a main part of a fourth embodiment of the present invention, FIG. 9 is a configuration diagram of a conventional example, FIG. 10 is a configuration diagram of a related technology example, and FIG. 11 is another related technology. FIG. 7 is a waveform chart for explaining the operation of the example. 11 …… Electron endoscope device 12 …… Electron endoscope (electronic scope) 13 …… Light source, 14 …… Signal processor 15 …… Video processor 16 …… Monitor, 27 …… CCD 34 …… Drive signal Generator circuit 37 …… φ _S transmission cable 38 …… φ _S matching cable 39 …… φ _S matching resistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akinobu Uchikubo 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Katsuyuki Saito 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. Olympus Optical Co., Ltd. (72) Inventor Jun Hasegawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Within Olympus Optical Co., Ltd. (72) Inventor Katsuyoshi Sasakawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. Olympus Optical Co., Ltd. (72) Inventor Shinji Yamashita 2-34-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Yudai Nakagawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd.

Claims (1)

[Claims] 1. An electronic endoscope apparatus having an image pickup means composed of a solid-state image sensor and a first cable for transmitting a drive signal for driving the solid-state image sensor to the solid-state image sensor, one end of which is provided. And a second cable having a second end connected to a terminating means at a position separated from the solid-state image pickup device and a second end connected to a drive signal input end of the solid-state image pickup device. apparatus.