JP3398550B2 - Electronic endoscope device with electronic shutter function - Google Patents

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 having an electronic shutter function, and more particularly to a configuration of an electronic endoscope having an electronic shutter function as well as a light quantity adjusting function for controlling an output light quantity by driving a diaphragm.

[0002]

2. Description of the Related Art In an electronic endoscope apparatus, an iris control circuit for driving a diaphragm is provided as a light quantity adjusting function by a diaphragm. This type of iris control circuit is a CCD (Charge Coupled Device) which is an image pickup device. The aperture value is variably adjusted based on, for example, the brightness signal of the image obtained in (1) to control the output light amount so that the brightness of the image becomes constant.

Further, conventionally, an electronic shutter function for controlling the accumulated charge as an image signal of the CCD is also known. That is, in the CCD, an image signal (video signal) is formed by sequentially reading out charges accumulated in pixel units by the photoelectric conversion element, and the electronic shutter function determines the accumulation time of charges corresponding to the pixels. It is variably controlled to change the imaging time. With this electronic shutter function, the brightness of the image can be adjusted while
There is an advantage that the image quality can be improved by the shutter speed for a short time.

[0004]

By the way, the light amount adjusting function by the diaphragm and the electronic shutter function described above are the same in that the brightness of an image can be adjusted. Functions are often used. That is, when the light amount adjustment function is used, the accumulation time (shutter speed) is fixed to a certain value, and when the electronic shutter function is used, the diaphragm is fixed to a certain value.

However, the light quantity adjusting function has an advantage that the output light of the light source can be changed, and the electronic shutter function has
There is an advantage that a sharp image can be obtained by a high shutter speed and an excellent image quality can be obtained even when there is blurring or movement. In particular, in an electronic endoscope apparatus that forms a still image and observes a specific part in detail, if a good still image can be obtained even when there is a blur of the electronic endoscope or movement of the observed object, The usability will be further improved.

[0006] The present invention has been made in view of the above problems, and an object, can benefit both functions of light intensity adjustment function and the electronic shutter function, employing the all-pixel reading scheme was or Accordingly, it is an object of the present invention to provide an electronic endoscope apparatus having an electronic shutter function that can further enhance the effect of the electronic shutter function.

[0007]

In order to achieve the above object, an electronic endoscope apparatus according to the present invention drives an aperture to output a light source based on a luminance signal of a pixel signal obtained by an image sensor. A light amount control means for controlling the light amount, an electronic shutter control circuit for controlling the accumulation time of the image signal in the image sensor as a shutter speed, and a shutter speed that is increased when it is determined that the aperture of the light amount control means is not fully opened. When it is determined that the aperture is fully open,
For the main control circuit for controlling the shutter speed to be low and the image signal accumulated for each pixel by the same exposure in the image pickup device, the incident light within the field period next to this exposure is All pixel reading means for reading out the image signal of either the odd line or the even line while reading off the image signal of the remaining line while blocking is cut off. According to a second aspect of the present invention, a memory for all pixels for storing the image signal of the odd line and the image signal of the even line obtained from the image sensor is provided,
When the freeze switch is operated, the main control circuit controls so as to prohibit writing at the time when the image signals of the odd line and the even line in the same exposure are stored in the memory for all pixels, and the writing in the same exposure is performed. A feature is that a still image is displayed based on image data.

According to the structure described in the first aspect, when the diaphragm is not fully opened, that is, when the endoscope is close to the site of the object to be observed and the amount of light is sufficient, the shutter speed becomes fast, and in this case, the sharpness is obtained. A clear image is obtained, and the effects of blurring and movement are reduced. In general, a still image is often photographed at a short distance, and high-speed still images can be observed by increasing the shutter speed. On the other hand, when the aperture is fully open, the shutter speed becomes slow and a sufficient amount of light can be obtained. For example, it is possible to avoid a situation where the light source light is insufficient in a state where the endoscope faces a direction with a depth.

Further , by the all-pixel reading means, for example, 1
With respect to the charges accumulated by the exposure within the 1/60 second period (vertical synchronization period), the odd line of the image pickup device is read out (read from the transfer line) in the second 1/60 second period, The remaining even lines are read in the third (next exposure period) 1/60 second period. Then, in order to read this even-numbered line, the light source light in the second period is blocked by the light blocking means. That is, if the charge of the next exposure is accumulated as in the conventional case during the second period in which the odd-numbered lines are being read out, the remaining even-numbered lines cannot be read out. Therefore, the light output in the second period is eliminated so that the accumulated charges of even lines can be read out in the third period, and this makes it possible to read out all the pixels of the image sensor obtained by one exposure. The signal can be read.

In this way, 1 within the period of 1/60 second
1 based on the signals of all pixels obtained by the same (same) exposure
An image of a frame is formed, and a high quality image (for example, a still image) can be obtained. As a result , the image quality improvement due to the electronic shutter function becomes more remarkable. That is, even if the charge storage time is shortened by the electronic shutter function, when an image is formed by two exposure signals as in the conventional case, the image moves between two exposures, and if there is blur, it affects the image quality. . However, in this case, since a still image is formed based on the video signal obtained by one exposure, the effect of shortening the signal storage time directly appears during this one exposure.

[0011]

FIG. 1 shows a circuit configuration of an electronic (simultaneous) endoscope apparatus having an electronic shutter function as an example of the embodiment. The endoscope apparatus is an electronic endoscope 10 as a scope, and a connector circuit (electronic endoscope internal circuit) 1 of the electronic endoscope 10
1, a processor device 12 and a light source device 13. The electronic endoscope 10 is provided with a CCD 15 provided with a color filter of a multi-color mosaic at the tip portion thereof, and a light guide 16 for guiding the light of the light source device 13 to the tip portion. Further, a freeze switch 17 for displaying a still image is provided on the operation unit of the electronic endoscope 10.

In the connector circuit 11, the CC
A CCD drive circuit 18 for driving D15, an all-pixel readout pulse generation circuit 19, and a shutter pulse control circuit 20 are provided. The all-pixel reading pulse generation circuit 19 generates a pulse for reading the accumulated data of all the pixels accumulated in the CCD 15 in one exposure by dividing it into an odd line and an even line. The control for reading the odd line signal and the even line signal separately from the CCD 15 is performed based on the read pulse. Further, the shutter pulse control circuit 20 forms a shutter pulse that determines the shutter speed in the electronic shutter function, and by changing the timing of this shutter pulse, for example, 1/60 second to 1/4.
A shutter speed of up to 00 seconds can be set.

Further, an A / D converter 21 for inputting the output signal of the CCD 15, a first memory 22 (memory for all pixels) for storing the image data of the odd lines, and a similar memory for storing image data of the even lines. A second memory 23, a mixing circuit 24, and a microcomputer (microcomputer) 25 that performs overall control including memory control are provided. That is, C
The video signal output from the CD 15 is divided into an odd-line video signal and an even-line video signal under the control of the microcomputer 25 in the respective memory 2
2 and 23 are once stored. Then, the above mixing circuit 2
In step 4, the odd-numbered line data and the even-numbered line data are added and mixed to form a signal equivalent to that of the conventional color difference line sequential mixing and reading method.

That is, in the conventional pixel mixed read-out, the CCD 1
The pixels of two horizontal lines above and below 5 are mixed and read sequentially. For example, a video signal of an odd (Odd) field such as a mixed signal of 0 line and 1 line, a mixed signal of 2 line and 3 line, ... Is read during the first exposure, and 1 line and 2 are read during the second exposure. Mixed signal of lines,
Even field video signals such as a mixed signal of 3 lines and 4 lines, ... Are read, and such a mixed signal of 2 lines becomes a signal of 1 line of a field image. On the other hand, in this example, the signals of all pixels are once stored in the memories 22 and 23, and then mixed and read out to form a mixed signal similar to the conventional one.

FIG. 2 shows the contents of the image data formed by the circuits from the CCD 15 to the mixing circuit 24 described above. As shown in FIG. 1A, the CCD 15 is provided with horizontal lines from 0 line to N line corresponding to the number of scanning lines, and pixel data of this horizontal line is transferred to a transfer line (not shown). It is configured to read. Then, the odd lines of the CCD 15 (1, 3, 5
The data of lines ... Is stored in the first memory 22 of FIG. 6B, and the data of the even lines (2, 4, 6 ... Line) is stored in the second memory 23 of FIG.

The data of the memories 22 and 23 for all pixels are subjected to pixel mixing by the mixing circuit 24 between the lines of FIGS. (B) and (C), and as shown in FIG. The addition operation data of 0 line + 1 line, 2 line + 3 line, 4 line + 5 line, ... Is output as odd (Odd) field data. Also, in the state where the read line of FIG.
(Reading out from the position), pixel mixing is performed between the lines shown in FIG. 2B and one line + 2 as shown in FIG.
Line, 3 line + 4 line, 5 line + 6 line, ...
The addition operation data of is output as even field data. Note that odd lines of the CCD 15 are ODD, even numbers are EVEN, odd numbers of fields to be interlaced scanned are Odd, and even numbers are even.

Further, in FIG. 1, a first DVP (digital video processor) 26 is provided at the subsequent stage of the mixing circuit 24, and the first DVP 26 carries out color signal processing of pixel mixed reading (color difference line sequential mixed reading system). Then, for example, a color difference signal and a luminance signal are formed.

In the processor device 12 to which the electronic endoscope 10 is connected, a second device connected to the first DVP 26 is provided.
A DVP 28 is provided, and in the second DVP 28, image position control, enlargement processing, mirror image processing, etc. are performed. In the subsequent stage of the second DVP 28, a third memory 29 (field image memory) for storing odd field data and a fourth memory 3 for storing even field data.
0, a switching circuit 31, a memory control circuit 32, and a D / A converter 33 are provided. That is, the third memory 29 stores the odd field data obtained by converting the data of FIG. 2D into a color difference signal, and the fourth memory 30 stores the data of FIG. The even field data converted into the same is stored.

A light source 35 is provided in the light source device 13 connected to the light guide 16 provided in the electronic endoscope 10. An optical chopper is provided between the light source 35 and the incident end of the light guide 16. 36 and diaphragm 37 are arranged. The optical chopper 36 is configured to rotate, for example, a semi-circular plate, and a drive circuit 38 and a servo circuit 39 are connected to rotate the optical chopper 36 once in 1/30 seconds. Therefore, according to this optical chopper 36, 1/60
In the field O / E signal of cycle every second, 1 /
It is possible to output light for 60 seconds and block the light for the next 1/60 second, and such an optical chopper 36 makes it possible to read the data on the even lines.

On the other hand, a drive circuit 40 and an iris control circuit 41 are connected to the diaphragm 37, and the drive circuit 40 and the iris control circuit 41 drive the diaphragm 37 based on a control signal from the microcomputer 25. . That is, the brightness signal obtained by the first DVP 26 is supplied to the microcomputer 25, and under the control of the microcomputer 25, the iris control circuit 41 supplies a control signal to the drive circuit 40 so that the brightness signal has a predetermined value. Thereby, the output light amount of the light source 35 is adjusted.

Further, the microcomputer 25 controls the shutter pulse control circuit 20 to change the electronic shutter speed according to the state of the diaphragm 37 controlled based on the brightness signal.

FIG. 3 shows a control operation relating to the electronic shutter in the microcomputer 25, and this control operation is performed every predetermined time such as 16.6 ms (millisecond). First, in step 101, it is determined whether or not the diaphragm 37 is fully opened. If not, the process proceeds to step 102 to speed up the electronic shutter. That is, when the diaphragm 37 is not fully opened, the endoscope tip portion is close to the object to be observed and sufficient light is emitted, and the shutter pulse control circuit 20 outputs a shutter pulse having a high shutter speed. Is output. As a result, for example, as shown in FIG. 4, when an image is captured at a shutter speed of 1/60 second, the shutter speed is switched to a higher shutter speed toward 1/200 second.

On the other hand, if it is determined in step 101 that the aperture 37 is fully open, the process proceeds to step 103 to slow down the electronic shutter. For example, as shown in FIG. 5, when an image is captured at a shutter speed of 1/400 second, the shutter pulse control circuit 20 forms a shutter pulse having a low shutter speed toward 1/200 second. The shutter speed in FIGS. 4 and 5 is 1/60
Rough settings such as seconds, 1/200 seconds, and 1/400 seconds can be set.

This example has the above-mentioned structure, and its operation will be described with reference to FIG. As shown in FIG. 6A, as the field O (Odd) / E (Even) signal, a timing signal for forming one field in 1/60 seconds is used as in the conventional device. Corresponding to this, the above optical chopper 36 is put into a used state,
By making one rotation in 0 seconds, Pn-1 in FIG.
As indicated by Pn and Pn + 1, the light is repeatedly output in the period of 1/60 second while sandwiching the light blocking state of 1/60 second. This light is emitted from the distal end portion into the body to be observed through the light guide 16.

By this light irradiation, the CCD 15 at the tip captures an image of the inside of the object to be observed, and charges corresponding to the image are accumulated in the CCD 15. The accumulation of the charges is shown in FIG. 6C. As shown by, the shutter speed is set within 1/60 seconds (described later) (t time). Then, the accumulated charge is read by the control pulse of the CCD drive circuit 18 to which the pulse of the all-pixel read pulse generation circuit 19 is input, and the CC obtained by one exposure is obtained.
The accumulated data of all the pixels of D15 are read.

That is, as shown in FIG.
Based on the exposure of the optical output Pn-1 of (B), n-1 odd (ODD) line data and even (EVE) are output from the CCD 15.
N) line data are sequentially read, the odd line data is stored in the first memory 22 by the write (write enable) signal of FIG. 6 (F), and the even line data is stored by the write signal of FIG. 6 (G). 2 is stored in the memory 23. Further, the data of the odd and even lines are read out in the order of the optical outputs Pn, Pn + 1 ...
2 and 23.

Next, the data in the memories 22 and 23 for all pixels are pixel-mixed by the mixing circuit 24, and the data in FIG.
As shown in (H), for example, an odd (Odd) field signal mixed with a combination of n-2 (th) odd line data and even line data, n-2 even line data, and n-1 Field signals are sequentially formed, such as an even field signal mixed with a combination of odd line data, an odd field signal mixed with a combination of n−1 odd line data and an even line data, and so on. To be done. Then, these field signals are subjected to color image processing and once stored in the third memory 29 and the fourth memory 30, and the outputs of these memories 29 and 30 are alternately output to the monitor by the switching circuit 31. Images are displayed by interlaced scanning.

Therefore, in this example, the moving image is displayed with a part of the image data obtained at the next exposure mixed, but this data amount is 1
It is / 2, and even if there is blurring or movement in 1/60 seconds, the effect is small.

Thus, in the image formation as described above, the shutter speed is controlled according to the state of the diaphragm 37. As described with reference to FIG. 3, it is determined whether or not the diaphragm 37 is fully opened, and when the endoscope distal end is close to the observed body part and light is efficiently emitted and the shutter is not fully opened, the shutter is opened. Speed up. That is, the shutter pulse control circuit 20 forms a shutter pulse that shortens the accumulation time. For example, when the shutter speed is 1/60 second (= t) in FIG. 4, the shutter speed is 1/200 second when the shutter speed is not fully opened, and the shutter speed is 1/400 second when the shutter speed is not fully opened. It is considered to be speed.

In the embodiment, 1/400 second is set as the maximum value of the shutter speed, and the maximum shutter speed can be set to any other value. In this example, the highest shutter speed is set to a slightly lower value, so that, for example, when a still image is formed at a short distance, the aperture 37 is 1/40 which is the maximum value before full opening.
A shutter speed of 0 second can be obtained.

On the other hand, when the front end is separated from the part to be observed and the diaphragm 37 is fully opened, the shutter speed is reduced. For example, when the shutter speed is 1/400 second (= t) in FIG. 5, the shutter speed is 1/200 second, and when the shutter speed is fully open, the shutter speed is 1/60 second. . For example, when photographing in a direction with depth, the aperture 37 is often fully opened even for 1/60 seconds, but when photographing the peripheral part necessary for observation, this 1
A shutter speed of / 60 seconds is sufficient.

In the light quantity control and the electronic shutter control by the diaphragm, a high shutter speed can be used for photographing at a short distance (still image etc.) and a sharp and high quality image can be obtained. Become. Moreover, when the distance becomes long, a sufficient amount of light can be obtained. Moreover, in the electronic endoscope adopting the all-pixel reading method as in this example, an image can be formed by one exposure, so that the shutter speed (accumulation time) is reduced within 1/60 second. ) Is directly brought about, and there is an advantage that in short-distance photography, the image quality can be improved by accumulating in the CCD 15 for a short time.

On the other hand, the still image is displayed by using only the data at the same exposure.
According to the control of No. 5, the first memory 22 is operated during the still image operation.
Also, control is performed to prohibit writing (write enable) to the second memory 23. For example, Q shown in FIG.
If the freeze switch 17 is turned on at the time of, it is determined that the still image operation is started at the fall of the field O / E signal (A1), and at the next fall (A1).
From 2), writing to the memories 22 and 23 is prohibited [FIGS. 6 (F) and (G)]. Accordingly, the n odd line data obtained at the optical output Pn is written in the first memory 22,
The next data is not written while the n even-numbered line data is also written in the other second memory 23.

As a result, as shown in FIG. 6 (H),
An odd number (Od) consisting of odd and even line data of n
d) The field signal and the even field signal are sequentially read out, and after these field signals are subjected to various kinds of signal processing, the third memory 29 and the fourth memory 30.
Then, it is displayed as a still image by interlaced scanning.

In this way, the combination of field images at different times is prohibited, and a still image is displayed based on the data of all pixels at the same exposure, so that a high quality in-vivo image can be observed. It becomes possible to do. Then, in such a still image, as described above, the image quality can be further improved by using the electronic shutter function.

[0036]

As described above, according to the first aspect of the present invention, the shutter speed is controlled to be high when it is determined that the aperture is not fully opened, and the shutter speed is determined when the aperture is fully opened. Since the speed is controlled so as to be low, the advantages of both the electronic shutter function that can obtain high image quality and the light amount adjustment function that can change the intensity of the output light itself can be enjoyed even if the camera shakes or moves. It becomes possible.

Further, since the applied new method for forming an image based on all pixel data obtained by the same exposure in the image pickup device, it is possible to utilize an electronic shutter function in the same exposure, high-quality There is an advantage that the effect of the obtained electronic shutter function can be further enhanced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a simultaneous type electronic endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing image data read from a CCD in FIG. 1 to a mixing circuit.

FIG. 3 is a flowchart showing a control operation of an electronic shutter function in the microcomputer of FIG.

FIG. 4 is a graph showing how the shutter speed is set when the aperture is not fully open.

FIG. 5 is a graph showing how the shutter speed is set when the state where the diaphragm is fully opened continues.

FIG. 6 is an explanatory diagram showing the main operation of the embodiment.

[Explanation of symbols]

1, 15 ... CCD (imaging device), 10 ... Electronic endoscope, 11 ... Connector circuit, 12 ... Processor device, 13 ... Light source device, 17… Freeze switch, 18 ... CCD driving circuit, 19 ... All pixel readout pulse generation circuit, 20 ... Shutter pulse control circuit, 22, 23 ... Memory for all pixels, 24 ... Mixing circuit, 25… Microcomputer, 36 ... Optical chopper.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-3-153208 (JP, A) JP-A-4-341231 (JP, A) JP-A 61-66481 (JP, A) JP-A 61- 99474 (JP, A) JP 62-161339 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1/00-1/32

Claims (2)

(57) [Claims] 1. A light amount control means for controlling an output light amount of a light source by driving a diaphragm based on a luminance signal of a pixel signal obtained by an image pickup device, and a storage time of an image signal in the image pickup device as a shutter speed. When it is determined that the electronic shutter control circuit and the aperture of the light amount control means are not fully opened,
The shutter speed is controlled to be high, and when it is determined that the aperture is fully open, the main control circuit that controls to reduce the shutter speed and the image sensor accumulates pixel by pixel by the same exposure. All pixels for which the image signal of either the odd line or the even line is read out first, and then the image signal of the remaining line is read out while blocking the incident light within the next field period of this exposure An electronic endoscope apparatus having an electronic shutter function including a reading unit. 2. A memory for all pixels for storing the image signal of the odd line and the image signal of the even line obtained from the image pickup device is provided, and the main control circuit is configured to operate when a freeze switch is operated. It is characterized in that the memory for all pixels is controlled to prohibit writing at the time when the image signals of the odd line and the even line at the same exposure are stored, and a still image is displayed based on the image data at the same exposure. An electronic endoscope apparatus having the electronic shutter function according to claim 1.