JPH0658459B2 - Illumination light supply device used for electronic endoscope device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination light supply device used in an electronic endoscope device 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 charges obtained as an image signal for each pixel are transferred at once to the storage unit of the solid-state imaging device (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 this image signal into a TV video signal and sends it to a monitor TV, which displays the image in the body cavity.

With respect to the above monitor television, pop-out scanning is performed as in a 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. 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. .

(Problems to be Solved by the Invention) However, in the conventional electronic endoscope apparatus, since the illumination light amount is constant, there is a drawback that the brightness of the image is greatly different depending on the usage mode of the endoscope. . More specifically, when the inner wall of the body cavity has a light color tone or when the inner wall is closely observed, the reflection efficiency is high, so a large amount of charge is stored in the solid-state image sensor, and the image on the monitor TV is too bright. Will end up. On the other hand, when the inner wall has a dark color tone or when the inner wall is observed from a distance, the reflection efficiency is low and the solid-state image sensor stores a small amount of electric charge, so that the image on the monitor television is too dark.

Further, in the conventional electronic endoscope apparatus, when it is necessary to make a precise diagnosis, a frame video memory stores a television video signal for one frame scanning, and a still image is displayed on a monitor television based on the television video signal. To observe
I'm recording on an optical disc or shooting with a camera,
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 pickup device continuously receives the reflected light for one field scanning time (1/60 seconds), and accumulates 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. 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.

(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 in which the image is converted into the television image signal and the image is displayed on the monitor television based on the television image signal, (a) the illumination light of the endoscope A diaphragm member disposed between the end of the transmission optical system and the light source, for continuously adjusting the area of the luminous flux of the illumination light within a predetermined range, and (b) a lightness detecting means for detecting the lightness of the image, C) A diaphragm drive mechanism for driving the diaphragm member based on the detected brightness signal obtained by the brightness detection means, and (d) detecting the position of the movable part of the diaphragm system including the diaphragm member and the diaphragm drive mechanism, A diaphragm sensor for detecting that the light flux area is at the upper limit value Lb and the lower limit value La of the predetermined range to be adjusted by the diaphragm member based on the detection position, and (e) the illumination light transmission optical system. Located between the edge and the light source A chopper having at least one window, (f) a motor for rotating the chopper so that the window of the chopper crosses the luminous flux of the illumination light, and (g) a short illumination light supply time T1 per rotation of the chopper. And a second position where the illumination light supply time T2 per rotation of the chopper is long, at least two positions; (c) a state in which the chopper is in the first position. When the upper limit value is detected by the aperture sensor, the chopper is moved from the first position to the second position, and when the lower limit value is detected by the aperture sensor while the chopper is at the second position, the chopper is moved. And chopper movement control means for controlling the chopper movement mechanism to move the chopper movement mechanism from the second position to the first position, and the ratio Lb / La between the upper limit value and the lower limit value is In the illumination light supplying device used in the electronic endoscope apparatus characterized by being set to be greater than the illumination light supply time ratio T2 / T1.

(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 illumination light from the light bulb 21 is reflected by the shade 22 and collected to collect the other end portion 18 of the optical fiber bundle 18.
b.

Further, the illumination light supply device 20 has a pair of diaphragm members 23 arranged between the light bulb 21 and the end portion 18b of the optical fiber bundle 18, and a disk-shaped chopper 30.

The pair of diaphragm members 23 are rotatably supported by a shaft 23a at an intermediate portion, have a wide shield portion 23b that shields the luminous flux X of the illumination light at one end, and the pin 2 at the other end.
3c is attached. A spring 24 is hooked on the pin 23c and pulls the pins 23c in directions toward each other. The shield portions 23b of the pair of diaphragm members 23 are arranged to approach or separate from each other to change the area of the light flux X and change the amount of illumination light passing through per unit time.

A diaphragm drive mechanism 25 for driving the diaphragm member 23.
Is a motor 26 (hereinafter referred to as a diaphragm motor), a detection plate 27 (movable part) fixed to an intermediate portion of the output shaft 26a of the diaphragm motor 26, and a cam fixed to an end portion of the output shaft 26a. 28 and. The cam 28 has a pair of cam surfaces 28a, and as shown in FIG. 2, it contacts the pins 23c provided on the pair of diaphragm members 23, respectively.

The detection plate 27 has a disk shape, and a shield portion 27a having a larger diameter than other portions in a predetermined angle range is formed in the peripheral portion thereof. In the vicinity of the detection plate 27, diaphragm sensors 29a and 29b formed of reflective photoelectric switches are arranged. These diaphragm sensors 29a and 29b are provided with different side edges 27a 'of the shielding portion 27a of the detection plate 27,
The position of 27a "is detected.

The set positions of the aperture sensors 29a and 29b are the lower limit value La and the upper limit value Lb in the range of the rotation angle of the cam 28, in other words, the adjustment range of the passing light amount (light flux area) of the illumination light by the aperture adjustment of the aperture member 23. To decide.

The central portion of the chopper 30 is fixed to the output shaft 38a of the rotation motor 38. As shown in FIG. 2, the chopper 30 is formed with a first window 31a and a second window 32a which are continuous with each other. More specifically, the second window 32a is formed by cutting out the peripheral portion of the chopper 30 at a relatively wide angle Θ _2, for example 180 °, and the other peripheral portion having the same diameter as the second window 32a is the first portion. It is two shielding parts 32b. Further, a first window 31a continuous with the second window 32a is formed on the center side of the second window 32a. The angle Θ ₁ of the first window 31a is narrower than that of the second window 32a and is 90 °, for example. The other portion having the same diameter as the first window 31a becomes the first shielding portion 31b.

Magnets 33 and 34 are attached to specific portions of the shields 31b and 32b of the chopper 30, respectively. Also,
A position sensor 35, which is a proximity switch, is arranged near the chopper 30 to detect the position of the magnet 33 or the magnet 34 on the chopper 30.

The rotation motor 38 and the chopper 30 have a moving mechanism 40.
By the direction (first line) orthogonal to the optical axis of the luminous flux X of the illumination light.
It is designed to be moved in the direction A-B in the figure). The moving mechanism 40 includes a stepping motor 41 (hereinafter, referred to as a moving motor), a pinion 42 fixed to an output shaft 41a of the moving motor 41, a rack 43 meshing with the pinion 42, and a rack 43 in a longitudinal direction thereof. And a guide (not shown) for guiding. One end of the rack 43 is connected to the rotation motor 38.

In the processing box, as shown in FIG.
0 and other electric circuits are built in. Video circuit 50
Is connected to the solid-state image sensor 16 via the signal line 13. A frame memory 52 and a monitor television 53 are connected to the video circuit 50 via a processing circuit 51. These video circuit 50, processing circuit 51, frame memory 52, monitor TV 53
Since it is known, detailed description will be omitted.

A rotation motor control circuit 55 is connected to the video circuit 50 via a synchronization circuit 54. The rotation motor control circuit 55 drives and controls the rotation motor 38. The position sensor 35 is connected to the synchronization circuit 54. A tacho generator 39 (only shown in FIG. 3) provided on the output shaft 38a of the motor 38 is connected to the rotation motor control circuit 55.

Further, an integration circuit 56 (brightness detection means) is connected to the video circuit 50, and a diaphragm motor control circuit 57 is connected to the integration circuit 56. The diaphragm motor control circuit 57 controls the driving of the diaphragm motor 26.

The diaphragm sensors 29a and 29b described above are connected to a moving motor control circuit 58 (chopper movement control means). The movement motor control circuit 58 controls the movement of the movement motor 41.

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 charge for one field scan is 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 50. In the video circuit 50, the image signal S from the storage unit 16 a of the solid-state image sensor 16 is used.
g, it is converted into an NTSC television video signal St and sent to the monitor television 53. As a result, an image of the inner wall of the body cavity is displayed on the monitor television 53 by the interlaced scanning method. The operator operates the endoscope 10 while watching the monitor TV 53 to observe the inside of the body cavity.

By the way, as described above, when the inner wall of the body cavity has a light color tone or is closely observed, the reflection efficiency is high, that is, the illumination light emitted from the illumination window 15 is reflected by the inner wall and enters from the observation window 14. Since the ratio of the amount of light emitted is high, the image on the monitor TV 43 becomes too bright if the supply of illumination light is constant. Further, when the inner wall of the body cavity has a dark color tone or is viewed from a distance, the reflection efficiency is low and the illumination window 15
Of the illumination light emitted from the inside of the observation window 14 by being reflected by the inner wall
Since the ratio of the amount of light entering from the monitor is low, the image on the monitor TV 43 becomes too dark if the illumination light is constant. However, in the device of the present invention, since the supply of the illumination light is adjusted, such a remarkable change in the brightness of the image does not occur, and an appropriate level can be maintained.

More specifically, the brightness of the image is determined by the light receiving unit 1 of the solid-state image sensor 16.
6a is in a proportional relationship with the amount of electric charge stored for each field scanning time, and the amount of the electric charge stored is a value obtained by multiplying the reflection efficiency by the amount of illumination light per unit time (that is, the unit time received by the solid-state image sensor 16). The amount of reflected light per hit) is integrated by the illumination light supply time. Therefore, when the reflection efficiency is high, the illumination light amount or the illumination light supply time per unit time is reduced, and when the reflection efficiency is low, the illumination light amount or the illumination light supply time per unit time is increased, thereby It is possible to maintain the brightness at an appropriate level. In the device of the present invention, the diaphragm member 23 finely adjusts the passing light amount of the illumination light per unit time over a predetermined range steplessly, and the movement time of the chopper 30 roughly adjusts the illumination light supply time stepwise. The diaphragm drive by the diaphragm member 23 is
The movement of the chopper 30 is performed according to the brightness of the image, and the movement of the chopper 30 is performed according to the aperture degree of the aperture member 23.

First, the fine adjustment by the diaphragm member 23 based on the brightness of the image will be described. The video signal of the video circuit 50 is the integration circuit 5
The lightness of the image is detected by integrating at 6. The detected brightness signal Sm from the integrating circuit 56 is sent to the diaphragm motor control circuit 57. The diaphragm motor control circuit 57 drives and controls the diaphragm motor 26 so that the brightness signal Sm becomes a set level. When the cam 28 is rotated by the driving of the diaphragm motor 26, the opening of the shielding portion 23b of the diaphragm member 23 is changed and the area of the light flux X is changed, and the passing light amount of the illumination light per unit time is finely adjusted steplessly. . When the reflection efficiency increases, the cam 28 rotates clockwise in FIG. 1, the pins 23c move away from each other, and the shielding portions 23b approach each other, so that the amount of illumination light passing through decreases. When the reflection efficiency decreases, the cam 28 rotates in the counterclockwise direction, the shield portions 23b are separated from each other, and the passing light amount increases. As a result,
The image level can be kept constant.

Next, the rough adjustment by the chopper 30 will be described. The chopper 30 rotates once for each frame scanning time by driving the rotation motor 38. Further, the positional relationship of the chopper 30 with respect to the light flux X can be changed by the moving mechanism 40. That is, by rotating the moving motor 41 in the forward and reverse directions, the rotating motor 38 and the chopper 30 are stepped through the pinion 42 and the rack 43 by a predetermined amount in a stepwise manner.
It is moved in the AB direction in the figure.

By the movement, the supply time of the illumination light is controlled in three stages. First, the illumination light supply in the first stage will be described.
In the state where the rotation motor 38 and the chopper 30 are at the positions closest to the A direction (first position) in FIG. 1,
When the light flux X is located on the rotation loci of the first window 31a and the first shield portion 31b of the chopper 30 and the first shield portion 31b shields the light flux X, the illumination light is supplied from the illumination window 15 into the body cavity. Instead, the illumination light is supplied only when the first window 31a is at the position of the light flux X. As a result, illumination light pulses are intermittently supplied as shown in FIG.
Since the angle Θ _{1 of} the first window 31a is as narrow as 90 °, the illumination light pulse supply time T1 (illumination light supply time per one rotation of the chopper 30) becomes short.

Next, the illumination light supply in the second stage will be described. When the rotation motor 38 and the chopper 30 are in the intermediate position (second position), the light flux X is on the rotation locus of the second window 32a and the second shielding portion 32b of the chopper 30 as shown in FIG. When the second shielding portion 32b is located and blocks the light flux X, the illumination light is not supplied from the illumination window 15 into the body cavity, and the illumination light is supplied only when the second window 32a is at the position of the light flux X. Done. As a result, illumination light pulses are intermittently supplied as shown in FIG. Since the angle Θ _{2 of} the second window 32a is as wide as 180 °, the illumination light pulse supply time T2 is relatively long, which is exactly the same as in the first stage, 2
Double.

Next, the illumination light supply in the third stage will be described. In the state where the rotation motor 38 and the chopper 30 are located closest to the B direction in FIG. 1 (the third position), the light flux X deviates from the rotation locus of the chopper 30, and as a result, as shown in FIG. In addition, the illumination light is not pulsed and is continuously supplied. At this stage, it can be considered that the window with the angle Θ ₃ = 360 ° passes through the light flux X, and therefore the illumination light supply time T3 is twice as long as that in the second stage.

Next, the fine adjustment by the diaphragm of the diaphragm member 23 and the chopper 3
The relationship with coarse adjustment by moving 0 will be described. As described above, the cam 28 rotates clockwise so as to reduce the amount of light that passes through the diaphragm member, and the amount of light that passes through is the lower limit value L.
When it reaches a, the one side edge 27a 'of the shield portion 27a of the detection plate 27 which is interlocked with the cam 28 is detected by the diaphragm sensor 29a. This lower limit value detection signal Sk is sent to the movement motor control circuit 58, whereby the movement motor 41 is moved.
Rotates a certain amount forward, and the rotation motor 26 and the chopper 30
Is moved in the direction of arrow A in FIG. 1 to roughly adjust the illumination light supply time by half.

Further, when the cam 28 rotates clockwise to increase the passing light amount and reaches the upper limit value Lb of the passing light amount, the detection plate 2
The other side edge 27a ″ of the shield portion 27a of No. 7 is the diaphragm sensor 29b.
Detected by. This upper limit value detection signal Sj is sent to the movement motor control circuit 58, whereby the movement motor 41 is reversely rotated by a certain amount, and the rotation motor 26 and the chopper 30 are moved in the direction of arrow B in FIG. , Roughly adjust so that the illumination light supply time is doubled.

Next, the above adjustment will be described more specifically. For example, when the chopper 30 is performing the second-stage illumination light supply, that is, when the second window 32a and the second shielding portion 32b pass the light flux X, the observation window 14 of the endoscope 10 is used. When the arrow approaches the inner wall, the reflection efficiency increases, and the diaphragm member 23 correspondingly operates in the closing direction. Then, when the amount of passing light reaches the lower limit value La, the chopper 30 moves in the A direction and shifts to the illumination light supply of the first stage, and the first window 31a and the first shielding portion 31b pass the light flux X. Ready to go. Immediately after this movement, the illumination light supply time is halved in accordance with the angle ratio Θ ₁ / Θ ₂ of the windows 31a and 32a, so the charge stored in the solid-state image sensor 16 is halved, and the brightness level of the brightness signal Sm is also temporarily reduced. Halves to. At this time, the diaphragm motor control circuit 57
Controls the diaphragm motor 38 according to the brightness signal Sm to open the diaphragm member 23, increase the amount of light passing therethrough, and restore the image brightness to an appropriate level. Therefore, the amount of passing light increases corresponding to the reciprocal of the angle ratio Θ ₁ / Θ ₂ and becomes twice as much as immediately before the movement of the chopper 30.

Further, if the observation window 14 of the endoscope 10 separates from the inner wall while the chopper 30 is performing the second-stage illumination light supply in the same manner as described above, the reflection efficiency decreases, and the diaphragm member correspondingly. 23 operates in the opening direction. Then, when the passing light amount reaches the upper limit value Lb, the chopper 30 moves in the B direction and shifts to the third stage illumination light supply. Immediately after this movement, the illumination light supply time doubles according to the angle ratio Θ ₃ / Θ _2, and the brightness level of the brightness signal Sm also doubles temporarily.
At this time, the diaphragm member 23 is closed to reduce the amount of light passing therethrough and restore the image brightness to an appropriate level. Therefore, the amount of light passing through decreases in accordance with the reciprocal of the angle ratio Θ ₃ / Θ ₂ and becomes half of that immediately before the movement of the chopper 30.

In the above operation, the passage ratio amount ratio Lb / La is changed to the angle ratio Θ.
₂ / Θ ₁ , Θ ₃ / Θ ₂ (in other words, the passing ratio amount ratio Lb / La is set to the illumination light supply time ratios T2 / T1, T3 / T).
It is necessary to have a so-called hysteresis characteristic (greater than 2). This is because, if Lb / La is equal to or smaller than the above angle ratio, the diaphragm by the diaphragm member 23 cannot cope with the change in the brightness level due to the movement of the chopper 30, and hunting occurs. That is, when the chopper 30 moves in the A direction, the passage ratio amount at the diaphragm member 23 is the lower limit value La.
Reaches the upper limit value Lb. Then, the chopper 30 again moves in the B direction, and this is repeated endlessly. If Lb / La is excessively increased with respect to the above angle ratio, the action and effect of the chopper 30 will be weakened. When the two values are brought close to each other, the chopper 30 frequently reciprocates due to a slight change in the reflection efficiency, for example, the pulsation of the heart or the respiration. Therefore, Lb / La is appropriately selected within a range larger than the above angle ratio. Note that Lb
In order to maintain the relationship with / La, it is preferable that the angle ratio at each stage is always constant. In this embodiment, the angle ratio is 1: 2, but this can be arbitrarily selected.

As described above, the supply time of the illumination light pulse and the specific amount per unit time can be adjusted according to the reflection efficiency that varies depending on the usage mode, and the brightness of the image can be maintained at an appropriate level.

Further, since the diaphragm member 23 is adjusted steplessly, it is possible to cope with a slight variation in the reflection efficiency.

Further, the adjustment of the passing light amount by the diaphragm member 23 is performed by the light flux X.
Since it is performed by shielding more of the surrounding area than the central area, the peripheral area in the image on the monitor TV 53 becomes dark. Therefore, although there is a restriction on the diaphragm range, a large change in the reflection efficiency can be dealt with by largely changing the illumination light supply time by the chopper 30 as described above.

When the reflection efficiency is further increased in the illumination light supply in the first stage, the amount of light passing through the diaphragm member is the lower limit value L.
It is even smaller than a. Similarly, when the reflection efficiency further decreases in the third stage, the amount of passing light is the upper limit value Lb.
However, the aperture member 23 may be fully opened.

By the way, when a precise inspection is required, one frame scanning portion of the television video signal St is stored in the frame memory 52 according to a command from the processing circuit 51, repeatedly read by the processing circuit 51, and sent to the monitor television 53. A still image is displayed on the monitor TV 53. When the illumination light supply is in the first stage or the second stage, this still image has less blur than the conventional one because the illumination light becomes a pulse. Hereinafter, the reason and the supply timing of the illumination light pulse will be described.

The timing of supplying the illumination light pulse in the first stage and the second stage is controlled as follows. That is, the synchronizing circuit 54 detects a frame synchronizing signal that occurs once per frame scanning time, for example, a vertical synchronizing signal that occurs before the odd-numbered field scanning is started, in the television image signal St from the image circuit 50. To do. on the other hand,
The position sensor 35 detects the magnet 33 or 34 of the rotating chopper 30 and sends the detected position signal Spo to the synchronizing circuit 54. In addition, at the time of supplying the illumination light in the first stage, the position sensor 35 is arranged on the rotation locus of the magnet 34 on the outer side so that the position of the magnet 34 can be detected, and at the time of supplying the illumination light in the second stage. The position sensor 35 is arranged on the rotation locus of the magnet 33 on the inside so that the position of the magnet 33 can be detected. The synchronization circuit 54 compares the frame synchronization signal with the detected position signal Spo from the position sensor 35 to detect the phase difference, compares this with the set phase difference, and rotates the phase difference deviation signal Sre. It is sent to the motor control circuit 55. In the rotation motor control circuit 55, the detected speed signal S from the tacho generator 39
The rotation motor 38 is controlled based on v and the phase difference deviation signal Sre to control the rotation speed of the chopper 30.

As a result, as shown in FIG. 4, the window portion 3 of the chopper 30 is
The time when the central portions of 1a and 31a pass through the central portion of the light flux X is made to coincide with the time when the image signal to be subjected to the odd field scanning is transferred. In other words, the supply time of the illumination light pulse is divided in half at this transfer point.

When the illumination light pulse is supplied at the above timing, the light receiving portion 16a of the solid-state image sensor 16 stores a charge (that is, an image signal) because it becomes a dark field when the illumination light pulse is not supplied in each field scanning period. The electric charge corresponding to the amount of received light is stored for only a half of the supply time of the illumination light pulse. Further, the accumulation period of the image signal to be used for the odd field scanning is adjacent to the accumulation period of the image signal to be used for the subsequent even field scanning. As a result, the monitor TV 53
The still image for one field scan shown in Fig. 1 is composed by superimposing the images for the odd and even field scans accumulated in each half of the illumination light pulse supply time.

Therefore, in the above-described first-stage and second-stage illumination light supply, the still image is based on the image information accumulated during the illumination light pulse supply time, and is accumulated during one frame scanning period as in the conventional case. Compared with the video based on the image information, it has less blurring and can be made clear.

The present invention is not limited to the above-mentioned embodiment and various modes are possible. The diaphragm sensor that detects the boundary value of the light amount diaphragm range may detect a specific position of another movable part of the diaphragm driving mechanism, for example, a cam, or may detect a specific position of the diaphragm member. Further, a potentiometer may be provided as an aperture sensor on the output shaft or cam shaft of the aperture motor to obtain the boundary value signal. Further, the diaphragm member can adopt any shape.

Also, a narrow shield may be provided in the center of the window. The shielding light splits the illumination light supply pulse into two at short time intervals. Therefore, the illumination light can be evenly supplied for each field scan within the range of the short time interval in which the illumination light is not supplied even if the rotation motors are out of synchronization.

The lightness detecting means may be one that detects lightness by sampling.

The chopper having only one window may be moved in two steps. In this case, in the first stage, the window and the shielding portion alternately cross the light flux of the illumination light to obtain the illumination light pulse, but in the second stage, the light flux deviates from the rotation trajectory of the chopper, and the illumination light is continuously emitted. Supplied.

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

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.

Also, using a conventional endoscope equipped with an eyepiece, the light incident from the observation window is sent to the eyepiece through an optical fiber bundle or a lens, and a television camera for a monitor TV is attached to this eyepiece. You may wear it.

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 electronic endoscope apparatus of the present invention can be applied to industrial inspection.

(Effects of the Invention) As described above, in the present invention, the area of the luminous flux of the illumination light is changed by the diaphragm member to finely adjust the amount of the illumination light per unit time, and the chopper crosses the luminous flux of the illumination light. By moving in the direction, the supply time of the illumination light is roughly adjusted in stages, so that the brightness of the image can be reliably maintained at an appropriate level. Further, the chopper can supply the illumination light pulse for each one-frame scanning, and the image for one-frame scanning can be made clear even for a subject to be photographed that moves rapidly. Furthermore, by providing a hysteresis characteristic, it is possible to prevent hunting between diaphragm driving and chopper movement.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention,
FIG. 1 is a partially exploded perspective view showing an endoscope and an illumination light supply device in an electronic endoscope apparatus, FIG. 2 is a front view showing a positional relationship between a diaphragm member, a chopper and a luminous flux of illumination light, and FIG. FIG. 4 is a time chart diagram of an electric circuit diagram of the electronic endoscope apparatus. 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), 23 ...
... diaphragm member, 25 ... diaphragm drive mechanism, 26 ... diaphragm motor, 27 ... detection plate (movable part), 29a, 29b ...
... sensor, 30 ... chopper, 31a, 32a ... window,
31b, 32b ... shielding portion, 38 ... rotation motor, 4
0 ... Driving mechanism, 50 ... Video circuit, 53 ... Monitor TV, 56 ... Integrating circuit (brightness detecting means), 58 ...
Motor control circuit for movement (chopper movement control means).

Claims (1)

[Claims] 1. A solid-state imaging device receives an image entered through an observation window of an endoscope, an image signal from the solid-state imaging device is converted into a television video signal by a video circuit, and a monitor is performed based on the television video signal. In an illumination light supply device used for an electronic endoscope device configured to display an image on a television, (a) is disposed between an end of an illumination light transmission optical system of an endoscope and a light source, and A diaphragm member for continuously adjusting the area of the light flux within a predetermined range, (b) a brightness detecting means for detecting the brightness of the image, and (c) the diaphragm member based on a detected brightness signal obtained by the brightness detecting means. And (d) the position of a movable part of the diaphragm system including the diaphragm member and the diaphragm drive mechanism is detected, and the light beam area is adjusted by the diaphragm member based on the detected position. Be at the upper limit value Lb of the range, And (e) a chopper having at least one window disposed between the end of the illumination light transmission optical system and the light source, and (f) a window of the chopper. The motor that rotates the chopper so that the light beam traverses the luminous flux of the illumination light, the (1) first position where the illumination light supply time T1 per rotation of the chopper is short, and the illumination light supply time T2 per rotation of the chopper are A chopper moving mechanism for moving the chopper between at least two positions including a long second position; and (h) a first chopper when the upper limit value is detected by the aperture sensor while the chopper is at the first position. From the second position to the second position, and the chopper is moved from the second position to the first position when the lower limit value is detected by the aperture sensor in the state where the chopper is at the second position. Above A chopper movement control means for controlling the chopper movement mechanism, and the ratio Lb / La between the upper limit value and the lower limit value is set to be larger than the illumination light supply time ratio T2 / T1 at this time. An illumination light supply device used in an electronic endoscope device characterized by the above.