JPH11244229A - Electronic endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To faithfully reproduce a motion in a dynamic picture and to provide a clear picture image without blur in a static picture. SOLUTION: This electronic endoscope device is provided with a CCD drive circuit 16 for driving a CCD 12, a microcomputer 18, a diaphragm drive circuit 22 for driving a diaphragm 20, a DVP 27 for forming a luminance signal, etc. The diaphragm drive circuit 22 controls the opening amount of the diaphragm 20 to a fully opened value or a fixed value close to the fully opened value based on the luminance signal obtained by the DVP 27 and switches to a high electronic shutter speed by the CCD drive circuit 16 when a freeze switch 15 is pressed. According to this configuration, a clear static picture can be provided without blur in a state of proper light quantity maintained, because a light receiving amount corresponding to an increase of light quantity due to the opening operation of the diaphragm 20 is reduced by exposing in a short time.

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 an apparatus for controlling the amount of light emitted to an object to be observed by using a diaphragm. Related to the configuration.

[0002]

2. Description of the Related Art In an electronic endoscope device, for example, a CCD (Charge Coupled Device) is used as a solid-state image pickup device. It is configured to obtain a signal (video signal). In addition, a light source unit (or a separate device) is provided to supply illumination light to the body to be observed. In this light source unit, an optimal light amount can be obtained by a diaphragm control mechanism.

That is, an image signal output from the CCD is supplied to, for example, a digital video processor (DVP), where a color difference signal, a luminance signal, and the like are formed. The luminance signal is a control signal for luminance adjustment. Is supplied to the aperture driving circuit. In this aperture driving circuit, the aperture is driven so that the luminance signal is constant. When the luminance signal is smaller than the reference value, the aperture is opened, and when the luminance signal is larger than the reference value, the aperture is closed. Controlled. By the variable control of the aperture opening amount, the irradiation light amount from the front end portion changes, whereby the brightness of the image can be kept constant.

[0004]

However, in the above-mentioned conventional electronic endoscope apparatus, for example, the exposure time is a fixed time slightly shorter than 1/60 second which is a vertical synchronization period (one field period). CC with fixed exposure time
Since the image is formed based on the charge accumulated in D,
A moving image is good, but a still image has a problem that image quality is deteriorated. In other words, in the case of a moving image, it is often better to faithfully reproduce the movement of the subject or the like with a long exposure time. If there is, the resolution, color shift and the like of the image are reduced, resulting in an unclear image.

The present invention has been made in view of the above problems, and has as its object to provide an electronic endoscope capable of faithfully reproducing motion in a moving image and obtaining a clear image without blur in a still image. A mirror device is provided.

[0006]

In order to achieve the above-mentioned object, the present invention irradiates light output from a light source unit to form a moving image from an image signal obtained by an image pickup device, and further comprises a freeze switch. In an electronic endoscope apparatus that forms a still image based on an operation, a light source diaphragm that detects brightness from the image signal and variably controls output light of the light source unit by a diaphragm so that the brightness of the image is constant. A control mechanism, an electronic shutter function for controlling the amount of light received by the image sensor with an electronic shutter speed, and a light source aperture control mechanism and an electronic shutter function are controlled. When the freeze switch is pressed, the aperture is fully opened or Control means for driving the electronic shutter speed to drive to a fixed value close to full open and to reduce the amount of received light corresponding to an increase in the amount of light due to the opening operation of the aperture. And it features.

[0007] According to the above configuration, during normal moving image formation, the aperture value is variably driven by the light source aperture control mechanism to which the luminance control signal has been input, and the brightness of the image is controlled to be constant. At this time, the electronic shutter function does not function in principle. When the freeze switch is pressed, the electronic shutter function is set so that the aperture is fully opened (or a fixed value close to full open), and at the same time, the electronic shutter speed is set to a high electronic shutter speed corresponding to the previously set aperture value. Will work.

That is, in comparison with a fully opened aperture value (light amount) fixed at the time of freeze, an electronic shutter speed appropriate for reducing an increase in light amount from each aperture value (light amount) is calculated and set in advance. For example, a high (short) shutter speed can be automatically selected from the aperture value immediately before the freeze switch is pressed, and the shutter speed can be made to function. By this short time exposure, a clear still image without blurring or the like can be obtained.

[0009]

FIG. 1 shows a circuit configuration of an electronic endoscope apparatus as an embodiment. This electronic endoscope apparatus includes a scope (electronic endoscope) 10 for image processing. It is configured to be connected to a processor device having a circuit or a light source device (light source unit). The scope 10 is provided with a CCD 12 as an image pickup device at a distal end thereof, and a light guide 14 for guiding light from a light source to the distal end.
Further, a freeze switch 15 for displaying a still image is provided on the operation unit of the scope 10.

The CCD 12 is connected to a CCD drive circuit 16 which drives the CCD and has an electronic shutter function. The drive circuit 16 includes a timing generator 1
7. A microcomputer (microcomputer) 18 for performing various controls including an aperture control and an electronic shutter control, which will be described later, is connected to the microcomputer 18, and an operation signal of the freeze switch 15 is input to the microcomputer 18. The CCD drive circuit 16
Inputs a timing signal based on the control of the microcomputer 18 and performs drive control of pixel mixed reading (color difference line sequential mixed reading method) for a moving image or a still image. That is, CCD1
By reading pixels while mixing pixels of two upper and lower horizontal lines (two lines) and shifting the positions of the lines for the mixed reading, image signals of odd-numbered fields and even-numbered fields are sequentially obtained.

The CCD drive circuit 16 controls the shutter speed (exposure time), for example, by changing the charge accumulation time by adjusting the charge discharging time of the CCD 12 when forming a still image, as will be described in detail later. The shutter speed can be set from about 1/60 second to a maximum of 1/100000 second.

On the other hand, the light guide 14 is provided with a stop (movable stop) 20 and a lamp 21 such as a halogen lamp via a condenser lens or the like in a light source section. The light source section drives the stop 20. An aperture drive circuit 22,
A lamp driving circuit 23 for controlling lighting of the lamp 21 is provided. The aperture 20 and the aperture drive circuit 22 may be of a type that switches the aperture amount (aperture value) of the aperture 20 to a limited number of steps (stepwise) or may be a type that continuously varies.

A DVP (Digital Video Processor) 27 as an image signal processing circuit is connected via an A / D converter 26 at a stage subsequent to the CCD 12.
The VP 27 can be provided with a red (R), green (G), blue (B) matrix circuit, an RGB gain circuit, a color difference matrix circuit, a gamma correction circuit, and the like. Here, a luminance signal (Y) and a color difference signal are provided. (C) will be formed. The luminance signal is input to the microcomputer 18, and a control signal of the luminance signal is supplied from the microcomputer 18 to the aperture driving circuit 22 when forming a moving image.
In No. 2, the aperture amount of the diaphragm 20 is variably controlled in response to the luminance control signal.

Further, when the freeze switch 15 is pressed, the microcomputer 18 controls the aperture 20 to be fully opened (or a fixed value close to fully opened), and causes the CCD drive circuit 16 to operate an electronic shutter function. The speed of the electronic shutter function is, for example, S2 to Sn [S2> Sn
(Second), S1: minimum speed], the aperture value of the aperture 20 [aperture An-1 to A1 (An-1> A1, An: fully open)]
The shutter speeds S2 to Sn can be set in accordance with the following conditions. When the aperture opening amount is A1 immediately before the freeze switch 15 is pressed, the shutter speed Sn (Sn-2 for A2, Sn- for A3). 3,... An-1 and so on).

In the subsequent stage of the DVP 27, a first memory 28 and a second memory 29 for storing data of an odd field and an even field, and a switching circuit 30 for switching between the first memory 28 side terminal and the second memory 29 side terminal. , D
/ A converter 31 is provided.

This example has the above configuration, and its operation will be described with reference to FIG. As shown in FIG. 2B, as a field O (Odd) / E (Even) signal,
As in the conventional case, a timing signal for forming a one-field image in 1/60 second (vertical synchronization period) is used. In the normal state, it is set so as to execute the moving image processing, that is, the pixel mixture readout method at the time of CCD output, and the light from the lamp 21 in FIG. Is done.

By this light irradiation, a moving image in the body to be observed is captured by the CCD 12 at the distal end, and electric charges corresponding to the image light are accumulated. This accumulated charge is transferred to the CCD driving circuit 1
The pixels between the upper and lower lines are added and read by the drive pulse from 6, and a pixel mixed signal of the odd field and the even field is output every 1/60 second. This moving image signal is supplied from the A / D converter 26 to the DVP 27, where a luminance signal is formed. Based on this luminance signal,
The microcomputer 18 sends a control signal for brightness adjustment to the aperture driving circuit 22.
Therefore, the aperture 20 is driven in the opening direction when the image is dark, and is driven in the closing direction when the image is bright.

The output of the DVP 27 is the first and second
The signals are supplied to the monitors via the memories 28 and 29, the switching circuit 30 and the D / A converter 31, and interlaced scanning is performed based on the odd field signal and the even field signal. In this way, a moving image of the inside of the observation subject with the optimal brightness is displayed.

On the other hand, when the freeze switch 15 of the scope 10 shown in FIG. 1 is depressed, the microcomputer 18 controls the light quantity for a still image. For example, as shown in FIG. 2A, if a trigger Tr1 (or Tr2) by the freeze switch 15 is given, only two field periods from t1 to t3 at the next rise of the O / E signal will be described. As shown in FIG. 2C, a fully-opened aperture control signal (voltage) is output, and the aperture drive circuit 22 outputs the aperture control signal.
0 is fully opened (An). Therefore, as shown in FIG. 3D, light is output when the aperture is fully opened.

At the same time, based on the control of the microcomputer 18, the CCD drive circuit 16 executes the electronic shutter operation shown in FIG. That is, in this example, the electronic shutter function is not operated at the time of moving image formation, and the instantaneous rising sweep pulse P1 is used as shown in the figure, so that TS1 of about 1/60 second, which is slightly shorter than one field period, is used.
Charge is accumulated during the exposure time, but when the image is switched to a still image, for example, the sweep pulse P for the time Th shown in the figure is used.
2 is used, and the short exposure time of TS2 (TS1
> TS2), that is, charges are accumulated at a high shutter speed.

The exposure time (shutter speed) T S2, which is set by the above-mentioned sweep time Th, is set to
Is determined by the aperture value (aperture An-1 to A1) immediately before is pressed. For example, the opening amount A is about 1/3 of the fully opened state.
If the freeze switch 15 is pressed when m is set, the aperture 20 is fully opened (An), and the electronic shutter speed is set from about 1/60 second to 1/180 second.
That is, since the light amount becomes about three times at the full opening, the exposure time can be reduced while maintaining the optimum light amount by setting the shutter speed to about 1/3.

Thereafter, as shown in FIG.
Between the time t2 and the time t3 of the O / E signal, the signal (pixel mixing signal) of the odd field obtained from the CCD 12 is stored in the first memory 28, and as shown in FIG.
The signal of the even field is stored in the second memory 29 during the period from to t4. Then, as shown in FIGS. 2 (H) and 2 (I), odd and even field signals are stored in each memory 28,
By alternately reading from the monitor 29, an image of the inside of the observed body is displayed on the monitor.

As a result, a still image can be formed at a high shutter speed by fully opening the aperture 20, and a high quality image can be obtained. Therefore, even if the endoscope itself is shaken or the object to be observed is moved, a clear still image with a small influence can be observed.

In the above embodiment, an image is formed by the pixel mixing method at the time of CCD output. However, the signal of all the pixels accumulated in the CCD 12 in one exposure is subjected to the light shielding period set by the light shielding means. The all-pixel read-out method that is read out by utilizing may be adopted only when a still image is selected. That is, when the freeze switch is pressed to execute the all-pixel reading method, a predetermined (first) 1/60 second period (for example, FIG.
In the second period (1/60 second), the odd lines of the CCD 12 are read out (read from the transfer line) and stored in a predetermined memory for the charges accumulated by the exposure during the period from t1 to t2). In the third period (at the time of the next exposure), the remaining even-numbered lines are read out and stored in a predetermined memory.

Here, in order to read out the even-numbered lines, the light source light in the second period is shielded by light shielding means. That is, if the charges of the next exposure are accumulated in the second period in which the accumulated charges of the odd-numbered lines are sequentially read out, the remaining even-numbered lines cannot be read out. Therefore, the light output in the second period is eliminated, and the accumulated charges in the even-numbered line are read out in the third period.
Thus, signals for all pixels of the image sensor obtained by one exposure can be read.

Next, the video signal of, for example, the odd line first stored in the above memory is further stored in the phase adjustment memory and is delayed by 1/60 second. A pixel mixing process is performed with the data of the even-numbered lines. For example, the added data of 0 line + 1 line, 2 lines + 3 lines, 4 lines + 5 lines,... Becomes odd field data, and the added data of 1 line + 2 lines, 3 lines + 4 lines, 5 lines + 6 lines, etc. becomes even field data. . As a result, this pixel mixing process forms a signal equivalent to the pixel mixing readout method at the time of output of the image sensor, which is performed at the time of signal output from the image sensor, but performs pixel mixing based on data obtained by one exposure. This is distinguished from the pixel-mixing readout method at the time of output of the image sensor.

Odd and even field signals are formed by the pixel mixture signal, and a still image is displayed based on these video signals. Therefore, a still image is formed based on signals of all pixels obtained by one exposure, and becomes a high quality image. The present invention can be similarly applied to an apparatus for forming a still image by such an all-pixel reading method. In this case, since an image signal is obtained by one exposure, the aperture control signal of FIG. 2C is output only for one field period from t1 to t2, and the aperture is fully opened as shown in FIG. Is only required during the period from t1 to t2.

[0028]

As described above, according to the present invention,
The light source aperture control mechanism and the electronic shutter function are controlled, and when the freeze switch is pressed, the aperture is driven to the full open or a fixed value close to the full open, and the electronic shutter speed is increased to increase the light amount due to the above-described aperture opening operation. Since the amount of received light corresponding to the increase is reduced, there is an advantage that a motion can be faithfully reproduced in a moving image and a clear image without blur can be obtained in a still image.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing an operation of the embodiment.

[Explanation of symbols]

 Reference numeral 12: CCD, 15: freeze switch, 16: CCD drive circuit (electronic shutter function), 18: microcomputer (control means), 20: aperture, 21: lamp, 22: aperture drive circuit, 23: lamp drive circuit, 27: DVP (Digital Signal Processor), 28, 29 ... Memory.

Claims (1)

[Claims] An electronic endoscope apparatus that irradiates light output from a light source unit to form a moving image from an image signal obtained by an image sensor and forms a still image based on an operation of a freeze switch. A light source aperture control mechanism for detecting brightness from the image signal and variably controlling the output light of the light source section by an aperture so that the brightness of the image is constant; and a light receiving amount of the image sensor at an electronic shutter speed. The electronic shutter function to be controlled, the light source aperture control mechanism, and the electronic shutter function are controlled. When the freeze switch is pressed, the aperture is driven to a fully opened state or a fixed value close to the fully opened state. Control means for increasing the electronic shutter speed in order to reduce the amount of received light corresponding to an increase in the amount of light.