JP2000267016A - Electronic endoscope device having variable power function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make suppressible the blur of an image and to make obtainable the stable brightness thereof when the image is picked up by utilizing a variable power mechanism. SOLUTION: An observing distance is changed by moving a movable lens 14 by an actuator 17 by the operation of a variable power switch 20. When the variable power position of the lens 14 is detected by an encoder 18 and a shutter speed being shorter than the exposure time of an inoperative time is set according to the variable power position by a CPU 31, the blur of the image is suppressed. Besides, the variable amount of a diaphragm 24 is restricted to prescribed width according to the increase of the electronic shutter speed. Then, when the brightness of the image becomes insufficient because of the restriction of the variable width of the diaphragm, the gain of a video signal is enhanced by an AGC circuit 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly to the content of light quantity control of an apparatus for imaging an object to be observed with a solid-state image sensor using a variable magnification function for changing an observation distance.

[0002]

2. Description of the Related Art Recently, it has been proposed to incorporate a variable power driving mechanism for changing, for example, an observation distance into an insertion end of an endoscope and drive a movable lens which is a constituent member of the variable power mechanism. I have. That is, for example, the rotational driving force of the motor is transmitted to the variable power mechanism using a linear transmission member, for example, a multiple coil spring member, where the rotational motion is converted into a linear motion and a predetermined movable motion of the objective optical system is performed. A variable power operation is performed by moving the lens back and forth, and there are a varifocal optical system for changing the observation distance, a zoom optical system with a variable focal length, and the like. According to this, the image of the object to be observed can be magnified and observed, and fine diagnosis can be performed.

[0003]

However, in the electronic endoscope apparatus having the zooming function described above, a detailed image of a lesion or the like can be observed on a monitor or the like by enlarging the inside of the object to be observed. There is a problem that blurring may occur. That is, the enlargement of the observed object image means that the shake due to the pulsation of the observation site, the shake due to the shaking of the distal end at the time of insertion, etc. appear as a large shake even if it is small at the time of standard observation. ), Which is not negligible especially when a still image is formed and recorded.

When a varifocal optical system is used for the zooming mechanism incorporated in the insertion end of the endoscope, when the observation distance is changed, the endoscope (objective optical system) is used for focusing. System) needs to be moved slightly back and forth. Therefore, as compared with the standard (normal) observation (when the zoom mechanism is not used), the image is more likely to be blurred due to the shake of the tip.

On the other hand, in this type of endoscope, automatic light quantity control for maintaining the brightness of an image constant by a diaphragm mechanism using a diaphragm member or the like is performed. This adjustment of brightness needs to be performed in a stable state.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to suppress blurring of an image when taking an image using a zoom mechanism and to obtain stable brightness of the image. It is an object of the present invention to provide an electronic endoscope apparatus having a variable power function that enables the zooming.

[0007]

In order to achieve the above object, an electronic endoscope apparatus having a variable power function according to claim 1 is a variable power mechanism capable of optically enlarging an observation image by an objective optical system. And a solid-state imaging device for imaging an object to be observed with incident light from the objective optical system, and controlling the charge accumulation time of the solid-state imaging device. An electronic shutter control circuit for setting a high shutter speed that is shorter than the exposure time, a diaphragm mechanism for variably controlling the output light from the light source with a diaphragm member, and a high speed of the electronic shutter speed when the magnification varying mechanism is operated. And a control circuit for limiting the variable aperture amount of the aperture mechanism to a predetermined width in accordance with the configuration. The invention according to claim 2 further includes a gain control circuit that variably controls a gain of an image signal output from the solid-state imaging device, wherein the control circuit detects brightness of an image from the image signal, and controls the aperture. When a predetermined brightness cannot be obtained by the light amount control by the mechanism, the gain of the image signal is adjusted by the gain control circuit to maintain the brightness of the image constant.

According to the above configuration, the standard time is about 1/60.
When the exposure time is seconds, the electronic shutter is set to, for example, 1/1000 second when the middle point is enlarged in the zoom function operation, and 1/10000 second when the maximum enlargement is performed. That is, the higher the magnification, the higher the speed,
The variable setting of the electronic shutter speed is performed by controlling a discharge pulse of charges accumulated in a CCD which is a solid-state imaging device and changing a charge accumulation time after the discharge.

The brightness of the image is controlled to be constant by driving the aperture mechanism even during the above-mentioned variable operation of the shutter speed. However, since the electronic shutter speed is set to a high speed, the variable width of the shutter speed is controlled. When the distance is large, when the object to be observed moves abruptly, or when the distal end portion of the endoscope moves greatly, the response of the aperture mechanism is delayed, the light amount adjustment becomes unstable, and the screen may be disturbed. Therefore, in the present invention, the aperture variable amount of the aperture mechanism is limited to a predetermined width in response to an increase in the electronic shutter speed, thereby eliminating a delay state of the response of the aperture mechanism and suppressing screen disturbance. Is done.

On the other hand, when the variable aperture amount is limited as described above, the amount of light for obtaining a constant brightness may be insufficient. Therefore, according to the configuration of claim 2, based on the determination of the image brightness based on the luminance signal or the like, if the brightness is insufficient, control is performed so as to increase the gain of the image signal. It is kept constant.

[0011]

1 and 2 show the configuration of an electronic endoscope apparatus having a variable magnification function according to an embodiment. The electronic endoscope (scope) 10 shown in FIG. The connector is connected to the light source and the processor device 12. In this electronic endoscope 10, a front lens 13 and a movable lens 14 that moves back and forth are provided as a varifocal objective optical system or a zoom objective optical system.
A D (Charge Coupled Device) 16 is arranged.

As shown in FIG. 2, the movable lens 14 is provided with a drive actuator 17 and an encoder 18 for detecting a lens drive position (magnification position). This encoder 1
8, the enlargement ratio is determined. Further, for example, an operation unit of the electronic endoscope 10 is provided with a zooming switch 20 including a toggle switch, a seesaw switch and the like, and a shutter speed setting switch 21 for manually setting a shutter speed. The switch 20 can move the movable lens 14 in the enlargement direction by connecting to the terminal a and in the contraction direction by connecting to the terminal b. In addition, a freeze button or the like for forming and recording a still image is arranged in the electronic endoscope operation unit.

A light guide 22 is provided from the electronic endoscope 10 to the light source and the light source section of the processor device 12. A stop 24 is provided at a light incident end of the light guide 22 via a condenser lens 23. A light source lamp 25 is disposed behind the stop 24. The diaphragm 24 is driven by a diaphragm driving circuit 26. In this example, the diaphragm 24 is controlled based on a luminance signal obtained by a processing circuit described later.
By controlling the opening amount of the image, the amount of output light is adjusted and the brightness of the image is kept constant.

Further, a diaphragm position (drive position) from the fully closed to fully opened position of the diaphragm 24 is detected by a diaphragm position detector (encoder or the like) 24D, and the detected value is converted to an A / D converter 27.
Is converted into a digital signal. FIG.
And the configuration of the position detector 24D.
For example, it is assumed that a fan-shaped aperture blade 24A rotates around a shaft 24B, and the rotation state of a root portion 24C of the aperture blade 24 is detected by a change in the voltage of an aperture position detector 24D, and the rotation position is the aperture position. To the A / D converter 27 as the detected voltage value.

In the light source and processor unit 12, an actuator drive circuit 28 for driving the actuator 17 and an A / D converter 29 for converting an analog output of the encoder 18 into a digital signal are provided. The converter 27 is the same, but is connected via an I / O unit 30 to a CPU 31 that controls each circuit. Therefore, when the variable power switch 20 is operated,
Actuator 1 via actuator drive circuit 28
7, the movable lens 14 is moved back and forth, and in this example, the observation distance (focal length) is set to a long distance (Far) by extending the movable lens 14 forward.
In the direction (Near
r) direction.

On the other hand, the moving position of the movable lens 14 is detected by an encoder 18, and the detected value is given to an actuator drive circuit 28 via an A / D converter 29, whereby the position of the movable lens 14 is controlled. You. The output of the encoder 18 is also supplied to the CPU 31 via the I / O unit 30 as a variable power position. The CPU 31 outputs an electronic shutter speed command signal based on the variable power position of the movable lens 14.

Further, a CCD drive circuit 33 including a timing generator (TG) is provided connected to the CCD 16. The CCD drive circuit 33 controls the drive of the CCD 16 and receives a command signal from the CPU 31. Execute electronic shutter control. This electronic shutter control changes the charge accumulation time (exposure time) by adjusting the sweep pulse (time) in the charge accumulation operation of the CCD 16, and as shown in FIG. 1 in 1/60 second vertical scanning period
The sweep pulse φSUB is output every H (horizontal scanning period). By outputting the sweep pulse φSUB for the time H1 as shown in FIG. 3A, the remaining charge accumulation time of 1/100 second, that is, the shutter speed Is set, and the output of the sweep pulse φSUB at time H2 as shown in FIG.
A shutter speed of 1/4000 second is set. And
The electric charge (exposure amount signal) accumulated at this shutter speed is read out at the end of the vertical synchronizing signal.

In such an electronic shutter control, in this example, a plurality of control patterns shown in FIG. 5 can be executed. That is, for example, in the ROM (Read Only Memory) 32 connected to the CPU 31,
The control patterns (tables) from 1 to S4 are stored, and the patterns can be selected by setting switches provided on an operation panel (not shown) of the light source and the processor device 12 or setting on a monitor screen. For example, when the pattern S4 as a simple control example is selected, when the movable lens 14 is enlarged from the standard position,
A shutter speed of 1/10000 second is set at all zoom positions.

On the other hand, in order to perform image processing on the video signal obtained by the CCD 16, a CDS (Correlated Double Sampling) / AGC (Automatic Gain Control) for performing a clamping process, a signal amplification process, and the like.
Automatic gain control) circuit 35, A / D converter 36, for example, a signal processing circuit 37 for forming a color difference signal C and a luminance signal Y and performing various processes such as gamma correction and contour correction, D / A
A converter 39 and an encoder 40 for performing output processing to a monitor
Are provided. In this example, the display processing of the electronic shutter speed is also performed together with the display processing of the observation object image. For example, as shown in FIG. 6, the electronic shutter speed set at the four corners E of the screen is displayed. Is done.

The luminance signal Y obtained by the signal processing circuit 37 is also supplied to the CPU 31.
At 31, the aperture of the aperture 24 is controlled via the aperture drive circuit 26 so that the luminance signal Y becomes a predetermined value, whereby the brightness of the image (screen) is maintained constant.
Therefore, even if the exposure time is shortened by the electronic shutter control, the output light amount is adjusted, and the brightness of the image is kept constant.

Further, in this example, the variable amount of the diaphragm 24 is limited to a predetermined width when the magnification varying mechanism is operated. That is, FIG.
As shown in the figure, if the vertical axis is the aperture opening amount, the lowermost end is fully closed, and the uppermost end is fully open, in the standard time (when the variable-magnification mechanism is not operated), all the areas such as the width K1 are used. For example, at the middle point of the magnification, the width K2 (aperture position k2-
k3), at the maximum position, the usable range is limited to the width K3 (aperture positions k1 to k2). This variable width K is basically set to be smaller as the image enlargement ratio increases and the electronic shutter speed is set to a higher speed. by this,
It is possible to eliminate a response delay of the diaphragm mechanism (24) due to an increase in the electronic shutter speed. Such limit data (table) of the diaphragm 24 is stored in the ROM 32 together with the pattern of the electronic shutter speed, and is executed by reading the limit data from the ROM 32.

In particular, when the varifocal optical system as described above is used as the lens system of the zoom mechanism, it is necessary to slightly move the distal end of the endoscope for focusing during zooming operation. To increase the magnification, the user moves a little forward. For this reason, the tip of the light guide also moves to the front side, and the amount of light illuminating the object to be observed is in the direction of increasing. Therefore, even if the variable width of the aperture 24 is limited as described above, the brightness of the image rarely changes extremely.

However, the brightness of the image is not always sufficient. Therefore, when the CPU 31 of the present example determines that the light amount is insufficient based on the luminance signal or the like when the variable width of the diaphragm 24 is limited, the CPU 31 sets the CDS / AGC.
The automatic gain control circuit of the circuit 35 is controlled so as to increase the gain of the image signal (video signal). As a result, the brightness of the image is always kept constant.

As described above, according to the configuration of this embodiment, the light from the light source lamp 25 shown in FIG.
Is irradiated from the distal end of the electronic endoscope 10 through the optical system, whereby the object to be observed is CC-connected through the objective optical systems 13 and 14.
Captured at D16. When the variable power switch 20 of the operation unit of the electronic endoscope 10 is not operated and the movable lens 14 is at the standard position, the electronic shutter control and the restriction of the variable amount of the aperture mechanism are not performed. For example, about 1/60 after the output of the fixed sweep pulse φSUB
The electric charges accumulated during the time of second (the exposure time is arbitrary) are read. Then, the read signal is processed as a video signal, so that the encoder 40 outputs a color difference signal C and a luminance signal Y, whereby an image of the inside of the body to be observed is displayed on the monitor.

On the other hand, when the magnification switch 20 is operated,
The actuator 17 is driven by the control of the actuator drive circuit 28 to move the movable lens 14 from the standard position to the front side, thereby enlarging the image. At the same time, the encoder 18 detects the zoom position (enlarged position) of the movable lens 14, and this position detection value is used as a control value in the actuator drive circuit 28, and the current zoom position information CPU 31 via the I / O unit 30
Supplied to Then, in this CPU 31, RO
An electronic shutter speed command signal corresponding to the current zoom position is output based on the control pattern in M32.

For example, the zoom position Z1 before the middle point in FIG.
Considering the case where the movable lens 14 is moving, the electronic shutter speed is 1/1 when the pattern S1 is selected.
000 seconds, 1/25 when pattern S2 is selected
A command signal is output to the CCD drive circuit 33 for 0 second, about 1/60 second (when OFF and the same time as the standard time) when the pattern S3 is selected, and 1/10000 second when the pattern S4 is selected. Will be. Then, this CCD
The drive circuit 33 controls the output (time H) of the sweep pulse φSUB, as described with reference to FIG. 4, whereby the electronic shutter speed is set. The value of the electronic shutter speed is displayed at the four corners E of the monitor 41 as shown in FIG.

As described above, when the image is enlarged by operating the zoom switch 20, the electronic shutter speed is increased, and an image of the inside of the body to be observed is formed by short-time exposure of the CCD 16. That is, even when the tip of the electronic endoscope 10 shakes, even when the observed part has a pulsation, etc., the blurring of the enlarged image is suppressed, a stable good moving image is formed, and the freeze button is pressed. Even when operated, a still image without blur is displayed.

At the same time, the CPU 31 controls the amount of light output from the diaphragm 25 via the diaphragm driving circuit 26 based on the input data of the luminance signal Y. The driving amount of the diaphragm 24 is limited to a variable width K, for example, K2 at the middle position of the enlargement, and K3 at the maximum position. That is, as shown in FIG. 3, the aperture position (rotational position) of the aperture blade 24A is detected by the position detector 24D and supplied to the CPU 31, and at the above-mentioned midpoint position, for example, the aperture positions k2 to k3. Drive to positions other than the above is prohibited.
Driving to any other position is prohibited. As a result, it is possible to eliminate the delay in the response of the diaphragm 24, and to suppress the disturbance of the screen.

When the CPU 31 determines that the brightness data is smaller than the predetermined value and the image is dark when the aperture variable width is limited, the CPU 31 sends a difference between the brightness signal data and the predetermined value to the CDS / AGC circuit 35. Is instructed to increase the gain of the video signal by an amount corresponding to. This allows
Since the AGC circuit 35 amplifies the video signal, it is possible to prevent the brightness of the image from being impaired by the restriction of the variable aperture width.

Further, in this embodiment, as described with reference to FIG. 1, a shutter speed setting switch 21 for manually setting the shutter speed is provided, and the electronic shutter speed during the variable power operation is set by the user. Can also be set manually. For example, the setting switch 21 is a switch whose value changes cyclically when pressed, so that the shutter speed of the patterns S4 and S5 can be set to a desired speed while checking the display (E) on the screen 41. it can.

FIG. 7 shows another example of the preferable setting range of the electronic shutter speed and the variable width of the aperture mechanism. The electronic shutter speed is set in the left area 100 delimited by the thick line L in FIG. It is preferable that the image blurring is favorably suppressed. Therefore, in this example, the shutter speed that can be manually set by the above-described shutter speed setting switch 21 is also limited to the range of the area 100.
Can not set the electronic shutter speed that exists.

The limited range of the diaphragm 24 is gradually reduced from the variable width K4 at the middle point (aperture positions k2 to k6), and the variable width K5 at the maximum position (the diaphragm positions k4 to k5).
) And K5 (aperture positions k5 to k7) may be set, and this variable width may be set arbitrarily.

[0033]

As described above, according to the present invention,
A variable power mechanism for changing the observation distance is provided, and when the variable power mechanism is operated, a shutter speed shorter than the standard exposure time is set by an electronic shutter control circuit,
Since the aperture variable amount of the aperture mechanism is limited to a predetermined width in response to the increase in the electronic shutter speed, it is possible to suppress blurring of an image when taking an image using the variable power mechanism, and to achieve stable brightness. It is possible to obtain a perfect image.

According to a second aspect of the present invention, when the brightness of an image is detected and the predetermined brightness cannot be obtained even by the light amount control by the aperture mechanism, the gain of the image signal is adjusted by a gain control circuit. Since the adjustment is performed, there is an advantage that a constant brightness can always be obtained without darkening due to the limitation of the diaphragm movable width.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an electronic endoscope apparatus having a zooming function according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an imaging system in the electronic endoscope in FIG.

FIG. 3 is a diagram showing a configuration of a diaphragm member and a diaphragm position detector of FIG. 1;

FIG. 4 is an explanatory diagram showing an example of an electronic shutter operation in the embodiment.

FIG. 5 is a graph showing various patterns of electronic shutter control and an aperture variable width in the embodiment.

FIG. 6 is a diagram illustrating a display state of an electronic shutter speed on a monitor in the embodiment.

FIG. 7 is a graph showing another example of a preferred setting range of an electronic shutter speed and a variable aperture width in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Electronic endoscope, 12 ... Light source and processor device, 14 ... Movable lens, 16 ... CC
D, 17: Actuator, 18: Encoder, 20: Variable power switch, 24: Aperture, 2
4D: diaphragm position detector, 26: diaphragm drive circuit,
28: Actuator drive circuit, 31: CP
U, 32 ROM, 33 CCD drive circuit (electronic shutter control circuit), 35 CDS
(Correlated double sampling) / AGC (automatic gain control) circuit, 37 ... signal processing circuit.

Continued on front page F-term (reference) 2H040 BA00 BA03 BA10 CA10 DA12 DA41 GA02 GA11 4C061 AA00 BB02 CC06 DD00 FF40 HH28 LL02 NN01 NN05 PP12 RR02 RR03 RR06 RR15 RR17 RR23 SS04 SS08 TT01 TT09 BB03 AB05 AB17 AB09 CE06 CH02 EA01 ED02 ED03 FF02 HA12

Claims (2)

[Claims] A variable magnification mechanism for optically enlarging an observation image by an objective optical system; a solid-state imaging device for imaging an object to be observed with incident light from the objective optical system; An electronic shutter control circuit for controlling the time and setting a high shutter speed that is shorter than the exposure time when the zoom mechanism is not operated when the zoom mechanism is in operation; A variable power function comprising: an aperture mechanism for variably controlling; and a control circuit for limiting the variable aperture of the aperture mechanism to a predetermined width in response to an increase in the electronic shutter speed when the variable power mechanism operates. An electronic endoscope device having the same. 2. A gain control circuit for variably controlling a gain of an image signal output from the solid-state imaging device, wherein the control circuit detects brightness of an image from the image signal,
The method according to claim 1, wherein when a predetermined brightness is not obtained by the light amount control by the aperture mechanism, the gain of the image signal is adjusted by the gain control circuit to maintain the brightness of the image constant. An electronic endoscope device having a zooming function according to claim 1.