JPH0646266B2 - Illumination light supply device used for electronic endoscope device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for supplying illumination light in an electronic endoscope apparatus in which an endoscope and a monitor TV are connected to each other.

(Prior Art) A publicly known electronic endoscope device will be described in detail. An insertion portion of an endoscope is inserted into a body cavity of a subject, and illumination light is emitted from an illumination window provided at a tip of the insertion portion. Then, the illumination light is reflected by the inner wall of the body cavity and returned, and enters from an observation window provided at the tip of the insertion portion, and the reflected light is arranged inside the observation window, such as a CCD solid-state image sensor. The light receiving unit receives the light and performs photoelectric conversion, and the charges as image signals of each pixel obtained by this are transferred to the storage unit of the solid-state image sensor at one time (the transfer time is very short, about 0.1 msec). . The image signal of each pixel stored in the storage unit of the solid-state image sensor is sequentially sent to the video circuit. The video circuit converts the image signal into a TV video signal and sends it to a monitor TV, which displays the image in the body cavity.

Interlaced scanning is performed on the monitor television as in the general television signal transmission / reception system. That is,
1 in 2 field scans, odd and even
Frame scanning is in progress. First, the odd-numbered field scanning roughly scans horizontally, and the even-numbered field scanning horizontally scans between the horizontal scanning lines. Such interlaced scanning is effective as a means for a fast-moving subject. It is also effective as a means for preventing flicker that occurs due to a short afterglow time of the phosphor of the CRT. In the interlaced scanning, the image signal to be used for each field scanning is sent from the solid-state imaging device to the video circuit, and the video circuit sequentially outputs a television video signal for odd-even field scanning based on the image signal. .

By the way, when it is necessary to make a precise diagnosis, one frame scanning TV image signal is stored in the frame memory, and a still image is displayed on a monitor TV based on this TV image signal for observation or recording on an optical disc. Do or shoot with the camera.

(Problems to be Solved by the Invention) However, the still image may not be clear, and precise diagnosis may be difficult. The reason is as follows.

Illumination light is continuously emitted from the illumination window into the body cavity. Each pixel of the light receiving portion of the solid-state image sensor continuously receives the reflected light for one field scanning time (1/60 seconds), and stores electric charges corresponding to the integrated value of the amount of received light. Therefore, when the movement of the observation target is fast, the amount of movement of the observation target in one field scanning time is stored as a blur of the image, and the sharpness of the image itself of the one field scanning is not sufficient. This principle is similar to the relationship between the shutter opening time of a camera and the sharpness of a captured image.
That is, in the camera, image information is continuously accumulated on the film during the time when the shutter is open, and therefore, if the opening time is long, the image of the fast-moving subject becomes unclear.

Moreover, the still image displayed on the monitor TV is 2
Since the images of the field scans of one time are overlapped and configured, the amount of movement of the observation target in one frame scanning time (1/30 seconds) eventually appears as a blur.

Therefore, the present inventor has developed the following technique. That is,
A chopper is arranged between the end of the illumination light transmission optical system of the endoscope and the light source, the chopper is rotated by a motor, and the window formed in the chopper crosses the luminous flux of the illumination light to illuminate intermittently. The light pulse is supplied to the illumination light transmission optical system. In this way, the time for storing image information (illumination time) in the solid-state imaging device is shortened to make the image clear.

However, the above-mentioned electronic endoscope apparatus may be inconvenient because the supply time of the illumination light pulse is constant. For example, when observing the upper gastrointestinal tract, in the esophagus that is affected by the heartbeat, the movement of the esophagus is severe and the image is likely to blur. The inner wall of the esophageal tube has a lighter color tone than other parts, and since it is observed closely, the illumination efficiency is high, so even if the illumination light pulse supply time is short and the illumination light amount is small, The solid-state image sensor can store a sufficient charge, and the image on the monitor TV does not become dark. On the other hand, since the stomach has a large volume and tends to be observed from a distance, the illumination efficiency is low, and a large amount of illumination light is required, so that it is preferable that the illumination light pulse supply time is long. Since the stomach moves slowly, image blurring is relatively small even when the illumination light pulse supply time is extended.

As described above, it has been desired to adjust the supply time of the illumination light pulse according to the usage mode.

(Means for Solving Problems) The present invention has been made to solve the above problems, and its gist is to receive an image entered through an observation window of an endoscope by a solid-state image pickup element, Image signal from the element,
In the illumination light supply device used for the electronic endoscope device that is converted into the interlaced scanning type television image signal in the image circuit and displays the image on the monitor television based on this television image signal, Two choppers arranged between the end of the illumination light transmission optical system of the mirror and the light source;
(B) Two motors for intermittently supplying the illumination light pulse by moving the above-mentioned two choppers to cross the luminous flux of the illumination light, and (c) either one of the odd-numbered and even-numbered motors. Based on the time point at which the image signal to be subjected to field scanning is transferred from the light receiving unit of the solid-state image sensor to the storage unit, the unblocking period of the one chopper with respect to the luminous flux of the illumination light should include this image signal transfer time point. In addition, first control means for controlling one of the motors so as to adjust the first time X between the start time of the shielding release period and the image signal transfer time, and (d) the image signal transfer. Based on the time point, the blocking release period of the other chopper for the luminous flux of the illumination light includes this image signal transfer time point, and between the end time point of this masking release period and the image signal transfer time point. Second control means for controlling the other motor so as to adjust the second time X ', and (e) equalizing the first time X and the second time X'and adjusting the time width thereof. An illumination light supply device for use in an electronic endoscope device, comprising: a control signal output means for outputting a control signal for controlling the first and second control means.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Reference numeral 10 in FIG. 1 denotes an endoscope.
Is an operation main body 11 having no eyepiece, and the operation main body 1
1 and the insertion part 12 extended from the front end. The insertion portion 12 is long and flexible, has a curved portion 12a on its distal end side, and further has a rigid distal end forming portion 12b on its distal end side. An observation window 14 and an illumination window 15 are provided on the end surface of the tip forming portion 12b. A solid-state image pickup device 16 composed of a CCD is arranged in the tip forming part 12b, and the light-receiving part 16a of the solid-state image pickup device 16 and the observation window 14 are optically connected via a convex lens 17. The signal line 13 is connected to the solid-state image sensor 16. The illumination window 15 is optically connected to one end portion 18a of the optical fiber bundle 18 (illumination light transmission optical system).

One end of a cable 19 is connected to the lower surface of the operation body 11, and the other end of the cable 19 is connected to a processing box (not shown). The optical fiber bundle 18 and the signal line 13 reach the inside of the processing box through the insertion portion 12, the operation body 11, and the cable 19.

An illumination light supply device 20 is built in the processing box. The illumination light supply device 20 has a light bulb 21 as a light source. The light bulb 21 is attached to the center of a shade 22 made of a concave mirror, and the light of the light bulb 21 is reflected by the shade 22 to be condensed and supplied to the other end 18b of the optical fiber bundle 18.

Further, the illumination light supply device 20 includes two servo motors 2
5 and 26 and two disk-shaped first and second choppers 27 and 28 having the same diameter. Servo motor 25, 2
6, the output shafts 25a and 26a of the chopper 2 respectively.
The central portions of 7, 28 are fixed. Each chopper 27,
The windows 27a and 28a are formed by cutting out the peripheral portion of 28 by 180 °.
Other peripheral portions having the same diameter as a are shield portions 27b and 28b.

A specific portion of each of the shielding portions 27b and 28b of the choppers 27 and 28, that is, exactly 1 with the central portion of the windows 27a and 28a.
Magnets 33 and 34 are attached at positions facing each other by 80 °. Position sensors 35 and 36, which are proximity switches, are arranged near the choppers 27 and 28 to detect the positions of the magnets 33 and 34 on the choppers 27 and 28, respectively.

In the processing box, as shown in FIG.
0 and other electric circuits are built in. Video circuit 40
Is connected to the solid-state image sensor 16 via the signal line 13. A frame memory 42 and a monitor television 43 are connected to the video circuit 40 via a processing circuit 41. These video circuit 40, processing circuit 41, frame memory 42, monitor TV 43
Since it is known, detailed description will be omitted.

In addition, the video circuit 40 includes an odd field integration circuit 47 and an even field integration circuit 4 via a selector 45.
8 is connected. A chopper control circuit 53 (first control means) is connected to the odd field integration circuit 47 via a comparator 49 and a selector 51. Further, the even field integrating circuit 48 includes a comparator 5
0, a chopper control circuit 54 (second control means) is connected via the selector 52. Comparator 49,
Reference numeral 50 constitutes a control signal output means to the chopper control circuits 53 and 54. Each chopper control circuit 53, 54 has
The drive of the motors 25, 26 is controlled to control the choppers 27, 2
The rotation of 8 is controlled.

A synchronizing circuit 60 is connected to the video circuit 40. The synchronization circuit 60 has a horizontal synchronization signal separation circuit 61, a vertical synchronization signal separation circuit 62, and a frame synchronization signal generation circuit 63.

An odd / even switching circuit 64 is connected to the synchronizing circuit 60 so as to switch the selector 45.

The synchronization circuit 60 includes two position deviation signal generation circuits 55,
56 is connected. These position deviation signal generation circuits 5
The selectors 51 and 52 described above are connected to 5 and 56, respectively. In the figure, 57 and 58 are selectors 5.
It is a comparator for switching and operating 1, 52.

The operation of the electronic endoscope apparatus having the above configuration will be described. The operator holds the operation body 11 of the endoscope 10 by hand and inserts the insertion portion 12 into the body cavity of the subject. For example, insert it through the mouth into the esophagus or stomach. The light from the light bulb 21 passes through the optical fiber bundle 18 and is emitted from the illumination window 15 into the body cavity. The reflected light from the inner wall of the body cavity reaches the solid-state image sensor 16 through the observation window 14 and the convex lens 17. As a result, the image of the inner wall of the body cavity is formed on the light receiving portion 16a of the solid-state image sensor 16.

The light receiving portion 16a of the solid-state image sensor 16 photoelectrically converts the projected image and stores the image signal as an electric charge. Then, in the solid-state imaging device 16, the electric charges for one field scanning are transferred from the light receiving unit 16a to the storage unit 16b in a short time by the transfer timing signal from the video circuit 40. In the video circuit 40, the image signal S from the storage unit 16a of the solid-state image sensor 16
g, converts it into an NTSC TV video signal St, and sends it to the monitor TV 43. As a result, an image of the inner wall of the body cavity is displayed on the monitor TV 43 by the interlaced scanning method.

The operator operates the endoscope 10 while watching the monitor TV 43 to observe the inside of the body cavity. When a precise inspection is required, one frame scan of the television video signal St is processed by the processing circuit 4.
It is stored in the frame memory 42 by the command 1 and the processing circuit 4
The still image is displayed on the monitor TV 43 by repeatedly reading out the data at 1 and sending it to the monitor TV 43.

Next, the supply of illumination light will be described in detail. Motor 25,2
By driving 6, the choppers 27 and 28 rotate, respectively. The choppers 27 and 28 make one rotation for each frame scanning time. When either the shield portion 27b of the first chopper 27 or the shield portion 28b of the second chopper 28 shields the luminous flux A of the illumination light, the illumination light is not supplied from the illumination window 15 into the body cavity, and both choppers 27. , 28 windows 27
The illumination light is supplied only when a and 28a are at the position of the light flux A. As a result, the illumination light pulse is supplied intermittently.

The supply time of the illumination light pulse can be adjusted by controlling the rotation of the choppers 27 and 28. Chopper 27,
The method of controlling the rotation of 28 differs between the transient period immediately after the start of driving the motors 25 and 26 and the stable period thereafter.

The control during the transition period is the synchronous control described below. More specifically, in the synchronizing circuit 60, the television video signal St from the video circuit 40 is sent to the horizontal synchronizing signal separating circuit 61 and the vertical synchronizing signal separating circuit 62. Horizontal sync signal separation circuit 61
Then, the horizontal synchronizing signal Sh and the equalized signal Sp are separated from the television video signal St, and these signals Sh and Sp are output to the frame synchronizing signal generating circuit 63. The vertical sync signal separation circuit 62 separates the vertical sync signal Sv from the television video signal St to generate a frame sync signal generation circuit 63.
Output to. In this frame synchronization signal generation circuit 63,
Based on the time difference between the last horizontal synchronization signal Sh received from the horizontal synchronization signal separation circuit 61 and the first equalization signal Sp, it is discriminated whether it is an odd field scan or an even field scan, and vertical synchronization is performed for each frame scan. When either one of the vertical synchronizing signals Sv sent from the signal separation circuit 62 twice, for example, the vertical synchronizing signal Sv for the odd-numbered field scanning is received (that is, once for each frame scanning). Then, the frame synchronization signal Sf is sent to the phase difference deviation signal generation circuits 55 and 56.

On the other hand, in the position sensors 35 and 36, the magnets 33 and 3
4 is detected and the detected position signal Spo is sent to the phase difference deviation signal generation circuits 55 and 56.

In the phase difference deviation signal generation circuits 55 and 56, the frame synchronization signal Sf from the frame synchronization signal generation circuit 63 and the detected position signal Spo from the position sensors 35 and 36 are compared to detect the phase difference. Compared with the set phase difference,
The phase difference deviation signal Sre is output. The phase difference deviation signal Sre is sent to the chopper control circuits 53 and 54 via the selectors 51 and 52.

In the chopper control circuits 53, 54, the position sensors 35, 3
From the frequency of the detected position signal Spo from 6 to the chopper 2
The rotation speeds of the choppers 27 and 28 are controlled by detecting the rotation speeds of the choppers 27 and 28 and increasing / decreasing the electric power supplied to the motors 25 and 26 based on the detected rotation speed and the phase difference. By this control, the time when the central portions of the windows 27a and 28a pass the light beam A is brought closer to the time when the image signal to be subjected to the odd field scanning is transferred.

Then, when the level of the phase difference deviation signal Sre becomes lower than the set phase difference deviation level Lre of the comparators 57 and 58, in other words, the window 27.
The selectors 51 and 52 are switched when the light flux passing times of a and 28a become substantially equal to the image signal transfer time.

By switching the selectors 51 and 52, control in the stable period, that is, control by lightness is performed. In detail,
The odd / even switching circuit 64 determines whether to receive only the vertical synchronization signal Sv from the vertical synchronization signal separation circuit 62 or to receive the vertical synchronization signal Sv and the frame synchronization signal Sf from the frame synchronization signal generation circuit 63 at the same time. Then, the selector 45 is switched. Every time the selector 45 is switched, the odd-field integration circuit 47 integrates the television video signal St of the odd-field scan to detect its brightness, and the even-field integration circuit 48 integrates the television video signal St of the even-field scan. Then, the brightness is detected.
Detected lightness signal Sm ₁ from the odd field integration circuit 47
Is sent to the comparator 49, which compares it with the set brightness level Lm and outputs the brightness difference signal S
Output me. Then, in the chopper control circuit 53,
Based on the brightness difference signal Sme and the detected rotation speed,
The rotation of the first chopper 27 is controlled to adjust the phase of the window 27a of the first chopper 27. That is, the time X (FIG. 4) from the time when the window 27a reaches the light flux A to the time when the image signal of the odd field is transferred is adjusted so that the level of the brightness signal Sm ₁ of the video of the odd field is the brightness level L.
Match m.

The time X is the supply time of the illumination light pulse when the solid-state imaging device 16 stores the image signal to be used for the odd field scanning (the first half of the total supply time of the illumination light pulse after the transfer point of the image signal). Equivalent to.

On the other hand, odd and even brightness signals Sm ₁ and Sm ₂ are sent to the comparator 50 from the integrating circuits 47 and 48, respectively, and the comparator 50 sends the brightness difference signal Sme ′ to the chopper control circuit 54 via the selector 52. Control circuit 5
In 4, the rotation of the second chopper 28 is controlled based on the brightness difference signal Sme 'and the detected rotation speed, and the phase of the window 28a of the second chopper 28 is adjusted. That is, the time X ′ from the time when the image signal is transferred to the time when the window 28a deviates from the light flux A is adjusted to match the levels of the brightness signal Sm ₁ of the odd field image and the brightness signal Sm ₂ of the even field image. . As a result, the time X becomes equal to the time X '. The time X ′ is the supply time of the illumination light pulse when the image signal used for even field scanning is stored in the solid-state image sensor 16 (the latter half of the total supply time of the illumination light pulse after the point of transfer of the image signal). ) Is equivalent to.

As described above, the brightness difference signal Sm from the comparator 49
The phase control of the first chopper 27 based on e is performed to adjust the supply time of the illumination light pulse so that the brightness becomes constant. Further, the phase control of the second chopper 28 based on the brightness difference signal Sme ′ from the comparator 50 is
Following the phase control of the chopper 27, this is performed in order to accurately divide the supply time of the illumination light pulse in half at the image signal transfer time point.

As described above, the supply time of the illumination light pulse is divided in half at the time point when the image signal is transferred. When the illumination light pulse is supplied at such timing, the solid-state imaging device 1
In the light receiving unit 16a of No. 6, when the illumination light pulse is not supplied in each field scanning period, the dark field occurs, so that the amount of light received is only half the period of the illumination light pulse supply without storing electric charges (that is, image signals). Will store an electric charge corresponding to. Further, since the accumulation period of the image signal to be used for the odd field scanning and the subsequent accumulation period of the image signal to be used for the even field scanning are continuous, one frame scanning displayed on the monitor television 43 is performed. Minute still image is two images (field scanning minute image) accumulated at each half of the illumination light pulse supply time.
It is composed by superposing.

Therefore, the still image is based on the image information accumulated during the supply time of the illumination light pulse, and has less blur compared to the conventional image based on the image information accumulated during one frame scanning period, Can be sharpened.

Further, since the choppers 27 and 28 are controlled so that the brightness of the image of the even-odd field scanning becomes equal, even if there is a manufacturing error of each component, a dimensional error due to a temperature change, or a characteristic change. The illumination light pulse can be accurately divided into halves at the transfer point, and the image displayed on the monitor TV 43 does not flicker, and the image quality is good and the color can be accurately reproduced.

The phase control of the choppers 27 and 28 is performed by the actual endoscope 1
It will be described in the usage mode of 0.

For example, when the endoscope 10 observes the esophagus, the wall surface of the esophagus has a light color tone, and since the observation is performed closely, the illumination efficiency is high. That is, the ratio of the amount of light reflected from the illumination window 15 and incident on the observation window 14 is high. In this case, the brightness of the image is adjusted to be constant by shortening the supply time of the illumination light pulse and reducing the amount of illumination light used for one-field scanning in response to high illumination efficiency. In the esophagus, since the movement of the heart is intense due to the effect of the heartbeat, it is preferable to shorten the supply time of the illumination light pulse, but the above adjustment satisfies this requirement.

In addition, for example, when the endoscope 10 observes the stomach, the stomach has a large volume and tends to be observed from a distance, and the illumination efficiency is poor. In other words, the illumination light emitted from the illumination window 15 is reflected. The ratio of the amount of light entering from the observation window 14 is low.
In this case, the brightness of the image is adjusted to be constant by increasing the supply time of the illumination light pulse and increasing the amount of illumination light to be used for one-field scanning in response to the low illumination efficiency. In the stomach, since the movement is relatively slow, it is possible to slightly increase the illumination light pulse supply time.

As described above, the supply time of the illumination light pulse can be adjusted according to each usage mode, the blurring of the still image can be surely prevented, and the brightness of the image can be made appropriate. Moreover, since the supply time of the illumination light pulse can be adjusted steplessly, it is possible to surely perform the adjustment suitable for the usage mode.

In the initial stage of driving the motors 25, 26, the time for which the choppers 27, 28 make one revolution is significantly different from the time for one frame scan.
6 is difficult to control. For this reason, the choppers 27 and 28 are first roughly controlled by the synchronous control.

Further, in the present invention, in addition to the operation of the above-described embodiment, by moving the two choppers in the direction intersecting with the light flux, the rotation locus of the chopper is removed from the light flux, and the illumination light can be continuously supplied. May be.

The position sensor is not limited to the proximity switch, but may be a photoelectric switch or the like.

In the above-mentioned two embodiments, the brightness of the image is detected, and the chopper is automatically moved based on this brightness signal. However, the switch may be manually operated to stop the chopper.

The two choppers do not have to have the same diameter. Also, the angular range of the windows of each chopper may be wider than 180 °.

There may be a plurality of windows of the chopper at equal angular intervals in the same diameter region. In this case, when the chopper makes one rotation, frame scanning is performed by the number of windows.

The chopper may be linearly reciprocated by a plate cam or the like rotated by a motor so as to cross the light flux.

The light incident from the observation window is received by one end surface of the optical fiber bundle,
This optical fiber bundle may be guided to the outside of the operation body in the same manner as the optical fiber bundle for illumination, and the solid-state image sensor may be arranged on the other end face.

Further, using a conventional endoscope having an eyepiece, the light incident from the observation window is sent to the eyepiece through the lens and the optical fiber bundle, and a television camera for a monitor TV is attached to the eyepiece. The television camera may be connected and the image from the endoscope may be received by the solid-state imaging device of the television camera.

You may record a still image on a monitor TV on an optical disc or shoot it with a hooded camera. Alternatively, one frame scanning portion of the moving image displayed on the monitor TV may be photographed by the hooded camera without using the frame memory.

The present invention can also be applied when the electronic endoscope apparatus is used for industrial inspection.

(Effect of the Invention) As described above, according to the present invention, the chopper is moved by the motor so that the luminous flux of the illuminating light is crossed, whereby the illuminating light pulse can be supplied for each frame scanning, and the subject to be photographed that moves rapidly. Even in this case, the image for one frame scan can be made clear. Moreover, the accumulation period of the image signal to be used for one of the odd-numbered and even-numbered field scans and the accumulation period of the image signal to be used for the other field scan thereafter can be made equal and continuous. Therefore, the image for one frame scanning can be made into a flicker-free image. Further, by changing the phases of the two choppers, the supply time of the illumination light can be adjusted steplessly, and appropriate illumination according to the usage mode can be performed.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention,
FIG. 1 is a perspective view showing an endoscope and an illumination light supply device in an electronic endoscope device, FIG. 2 is an electric circuit diagram of the electronic endoscope device, and FIG. 3 is a positional relationship between a chopper and a luminous flux of illumination light. And FIG. 4 is a time chart. 10 ... Endoscope, 11 ... Operation main body, 12 ... Insertion part,
16 ... Solid-state image sensor, 16a ... Light receiving part, 16b ...
Storage unit, 18 ... Optical fiber bundle (illumination light transmission optical system), 2
0: illumination light supply device, 21: light bulb (light source), 25,
26 ... Motor, 26, 27 ... Chopper, 27a, 2
8a ... window, 27b, 28b ... shielding portion, 40 ... video circuit, 43 ... monitor television, 49,50 ... comparator (control signal output means), 53 ... chopper control circuit (first control means) ), 54 ... Chopper control circuit (second control means)

Claims (2)

[Claims] Claim: What is claimed is: 1. An image input from an observation window of an endoscope is received by a solid-state image sensor, and an image signal from the solid-state image sensor is converted into a television video signal of an interlace scanning system by a video circuit. In the illumination light supply device used for the electronic endoscope device adapted to display the image on the monitor television based on (a), (b) is disposed between the end of the illumination light transmission optical system of the endoscope and the light source. Two choppers, and (b) two motors that intermittently supply the illumination light pulse by moving the above two choppers so as to cross the luminous flux of the illumination light, and (c) odd and even numbered times. Of the image signal to be subjected to the field scanning of any one of the above, with the time point of transferring from the light receiving unit of the solid-state image sensor to the storage unit as a reference, the unshielding period of the one chopper for the luminous flux of the illumination light is Belief A first control means for controlling one of the motors so as to include a transfer time point and adjust a first time X between the start time point of the shielding release period and the image signal transfer time point; D) With the image signal transfer time point as a reference, the blocking release period of the other chopper for the luminous flux of the illumination light includes this image signal transfer time point, and the end point of this blocking release time period and the image signal transfer time point Second control means for controlling the other motor so as to adjust the second time X'between (e) the first time X and the second time X'are made equal and An illumination light supply device for use in an electronic endoscope apparatus, comprising: a control signal output means for outputting a control signal for adjusting the width to the first and second control means. 2. The chopper is disk-shaped and has a window,
An illumination light supply device for use in an electronic endoscope apparatus, characterized in that the chopper is unblocked by rotating the chopper by a motor so that the window crosses the luminous flux of the illumination light.