JP3403588B2 - All-pixel readout electronic endoscope - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly, to reading out all pixels of an image stored by a simultaneous type image pickup device and producing a high quality still image or the like. The present invention relates to signal processing for an endoscope device to be formed. 2. Description of the Related Art In an electronic endoscope apparatus, for example, a CCD (Charge Coupled Device) is used as an image pickup device. In this CCD, a charge stored in a pixel unit by a photoelectric conversion element is read out. , An image signal (video signal) is obtained. In the simultaneous electronic endoscope device, a color filter is arranged in pixel units on the upper surface of the CCD so that a color image can be obtained. FIG. 5A shows an arrangement state of the color filters. As shown, for example, Mg (magenta), G (green), and Cy are provided on the imaging surface of the CCD 1.
(Cyan) and Ye (yellow) are arranged in pixel units. Therefore, by the light transmitted through these color filters,
In the CCD 1, accumulated charges are obtained. FIG. 5B shows a read state by a conventional color difference line sequential mixed read method. In this method, accumulated charges of pixels in upper and lower lines are mixed and read. For example, at the first exposure, a mixed signal of 0 line and 1 line, a mixed signal of 2 lines and 3 lines,..., And a video signal of an odd field (Odd) are read out. 2 lines mixed signal,
A video signal of an even field (Even) such as a mixed signal of three lines and four lines,... Is read out.
Therefore, a mixed signal of two lines of the CCD 1 becomes a signal of one line of the field image. FIG. 6 shows a signal reading operation in the CCD 1, and the O / O of the field shown in FIG.
1/60 second (vertical synchronization period) as indicated by E signal
An odd field and an even field are obtained every time. Therefore, during the above 1/60 second period, signal accumulation is performed, for example, according to the accumulation (exposure) time t of the electronic shutter shown in FIG. Reading is performed. As a result, as shown in FIG. 7C, n-1 (number) odd (Odd) field signals and n even (Even) field signals are obtained, and the (n-1) odd field signals are obtained. Are (0 + 1) lines and (2 + 3) shown on the left side of FIG.
, A mixed signal of (4 + 5) lines..., And the even field signal of n is (1) shown on the right side of FIG.
+2) lines, (3 + 4) lines... [0006] The odd field signal and the even field signal are interlaced and formed as an image of one frame, and the image is displayed on a monitor. Of course, in the middle of the above processing, various signal processings are performed, and a color difference signal and a luminance signal are formed from the mixed signal, and an image of the inside of the object to be observed is displayed on a monitor based on these signals. Is done. [0007] However, in the simultaneous electronic endoscope apparatus, as shown in FIG. 6C, an odd field image for forming one frame image and an odd field image for forming one frame image are used. 1/60 between even field image
If there is a time lag of seconds and the endoscope itself shakes or the object moves during this time, there is a problem that the image quality deteriorates. In particular, in the endoscope, a still image is displayed by operating a freeze switch, and thereby a specific observation site can be observed in detail. In this still image, an image of one frame is displayed based on the odd field information and the even field information. If there is a shift (blurring, movement) between the two, the image quality deteriorates (including color shift). Will do. In some cases, the electronic endoscope apparatus employs an electronic shutter function for changing a signal accumulation time.
According to this, the image quality can be improved by shortening the accumulation time in a bright place. However, as shown in FIG. 6B, there is a time lag of 1/60 second between two accumulations (exposure) for forming one frame image, and the effect of shortening the accumulation time is not necessarily required. There is also a disadvantage that it cannot be enjoyed. Conventionally, it has also been proposed to sequentially read out all pixels within a period of 1/60 second. However, in this case, the transfer line of the CCD 1 (vertical CC)
Since the structure of D) must be formed at twice the density, the structure becomes complicated and the clock frequency is doubled. The present invention has been made in view of the above problems, and an object of the present invention is to read out all pixels obtained by an image pickup device by one exposure without increasing the clock frequency, and to perform image reading . It is an object of the present invention to provide an all-pixel readout type electronic endoscope apparatus capable of improving quality. According to a first aspect of the present invention, there is provided an all-pixel read-out type endoscope apparatus in which a plurality of color filters are arranged in pixel units. In order to form an image sensor and a moving image and a still image, an image signal of either an odd or even line is first read out from an image signal accumulated for each pixel by one exposure with the image sensor, and An image sensor driving circuit that controls to read image signals of the remaining lines, and illuminating light so that pixel signals are not accumulated in the image sensor at a predetermined time when the image signal is read by the image sensor driving circuit. A light blocking means for blocking, a memory for storing the odd-numbered line image signal and the even-numbered line image signal obtained from the image pickup device, and a memory for controlling writing and reading of the memory;
When forming an image, the odd lines and lines obtained during the same exposure
And write so that only the image signals of even lines are stored
A memory control circuit for prohibiting control, a mixing circuit for forming an image signal of the simultaneous method by mixing the pixel signals of the odd lines and even lines read from the memory,
And forming a field image of a moving image and a still image based on the pixel mixing signal output from the mixing circuit , and
This still image is framed by the image signal of the same exposure.
Forming an image . According to the configuration of the first aspect, for example, the electric charge accumulated by the exposure (exposure time is optional) within the first 1/60 second period (vertical synchronization period) is reduced to the second charge. The odd lines of the image sensor (CCD) are read out during 1/60 second (read from the transfer line), and the remaining even lines are read out during the third (at the next exposure) 1/60 second. Then, in order to read out this even line, the light source light in the second period is blocked by the light blocking means. That is, if the charges of the next exposure are accumulated during the second period in which the accumulated charges of the odd lines are sequentially read out, the remaining even lines cannot be read. Therefore, in the present invention, the light output in the second period is eliminated, and the accumulated charges of the even lines are read out in the third period, whereby the imaging device obtained by one exposure is obtained. Signals for all pixels can be read. Next, the video signals of the odd-numbered lines and the even-numbered lines are respectively stored in a memory, and then the respective lines are simultaneously read out and mixed by a mixing circuit. That is, a pixel mixed signal is formed by the same method as the above color difference line sequential mixed reading method, and a video signal of odd field data and even field data is formed. This video signal is subjected to the same processing as before, and then output to a monitor or the like. In this manner, 1 based on the signals of all the pixels obtained by one exposure within the period of 1/60 second.
A frame image is formed, and a high-quality image can be obtained. Further, when the freeze switch has been pressed, the odd lines and the image signal of the even lines obtained at the time the same exposure when stored in said memory, writing to the memory is inhibited. Therefore, a still image is always displayed by a video signal obtained by the same exposure within a period of 1/60 second, and a high-quality still image can be observed. FIG. 1 shows a circuit configuration of an all-pixel readout type electronic endoscope apparatus as an example of an embodiment. As shown in FIG. Denotes an electronic endoscope 10 as a scope, a connector circuit (electronic endoscope internal circuit) 11 of the electronic endoscope 10, and a processor device 12.
And a light source device 13. The electronic endoscope 10
Is provided with a CCD 15 having a color filter similar to that described with reference to FIG. 5 and a light guide 16 for guiding the light of the light source device 13 to the distal end. Further, a freeze switch 17 for displaying a still image is provided on the operation unit of the electronic endoscope 10. In the connector section circuit 11, the CC
A CCD driving circuit 18 for driving D15, an all-pixel reading pulse generating circuit 19, and a timing generator 20 are provided. The all-pixel read pulse generating circuit 19 generates a pulse for reading the accumulated data of all the pixels accumulated in the CCD 15 by one exposure into odd lines and even lines based on the signal of the timing generator 20. Then, it is supplied to the CCD drive circuit 18. The CCD drive circuit 18 performs control for sequentially and sequentially reading the odd-line signal and the even-line signal from the CCD 15 based on the read pulse. An A / D converter 21 for inputting the output signal of the CCD 15, for example, a first memory 22 for storing the odd-line image data, a second memory 23 for storing the even-line image data, a mixing circuit 24, a memory control circuit 25 is provided. That is, the video signal output from the CCD 15 is not output by mixing two lines as in the related art, but is divided into an odd-line video signal and an even-line video signal under the control of the memory control circuit 25. In the state, each memory 2
2 and 23 once. Then, the above-mentioned mixing circuit 2
No. 4 adds and mixes the data of the odd-numbered lines and the data of the even-numbered lines to form a signal equivalent to that of the conventional color difference line sequential mixed reading method. FIG. 2 shows the contents of 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 to N corresponding to the number of scanning lines, and the pixel data of the horizontal lines is transferred to a transfer line and read. Is done. Then, data of odd lines (1, 3, 5,...) Of the CCD 15 are stored in the first memory 22 shown in FIG.
The data of the even lines (2,4,6 ... line) is shown in Fig. (C)
Is stored in the second memory 23. The data in the memories 22 and 23 are subjected to pixel mixing between the lines shown in FIGS. 2B and 2C by the mixing circuit 24, and as shown in FIG. The addition operation data of the line, 2 lines + 3 lines, 4 lines + 5 lines,... Is output as odd-number (Odd) field data. Further, with the readout line in FIG. 9C shifted downward by one line (reading from the position of C1 in FIG. 9), pixel mixing is performed between the lines in FIG. 10B and as shown in FIG. 10E. , 1 line + 2 lines, 3 lines + 4 lines, 5 lines + 6 lines,..., Are output as even field data. The odd number of lines of the CCD 15 is represented by O.
DD, an even number is distinguished as EVEN, an odd number of a field to be interlaced is identified as Odd, and an even number is identified as Even. Further, in FIG. 1, a first DVP (digital video processor) 26 is provided at a stage subsequent to the mixing circuit 24, and the first DVP 26 performs color signal processing of pixel mixed reading (color difference line sequential mixing reading system). Then, for example, a color difference signal and a luminance signal are formed. Although not shown, other circuits such as an automatic gain control circuit and a gamma processing circuit are arranged at appropriate positions. In the processor device 12 to which the electronic endoscope 10 is connected, a second DVP 26 connected to the first DVP 26 is provided.
A DVP 28 is provided. In the second DVP 28, control of an image position, enlargement processing, mirror image processing, and the like are performed. In the subsequent stage of the second DVP 28, a third memory 29 for storing odd field data, a fourth memory 30 for storing even field data, 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 or the like, and the fourth memory 30 stores the data of FIG. Is stored. A light source 35 is provided in the light source device 13 for connecting the light guide 16 provided in the electronic endoscope 10, and a light chopper is provided between the light source 35 and an incident end of the light guide 16. 36 and a stop 37 are arranged. The optical chopper 36 is configured to rotate, for example, a semicircular plate, and a drive circuit 38 and a servo circuit 39 are connected to rotate the optical chopper 36 once every 1/30 second. Therefore, according to the optical chopper 36, 1/60
In a field O / E signal in a cycle every second, 1 /
The light is output for only 60 seconds, and the light can be blocked for the next 1/60 seconds. 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 are connected to the first DVP 26.
By driving the aperture 37 based on the luminance signal obtained in the step (1), the output light amount of the light source 35 can be adjusted. This example is configured as described above, and its operation will be described with reference to FIGS. As shown in FIG. 4A, the field O (Odd) / E (Eve)
n) As a signal, a timing signal for forming one field in 1/60 second is used as in the conventional device. In response to this, the optical chopper 36 is rotated once every 1/30 second, so that Pn-1, Pn, and Pn-1 in FIG.
As indicated by Pn + 1, light is repeatedly output for a period of 1/60 second while interposing a light blocking state of 1/60 second.
This light is emitted from the distal end portion through the light guide 16 into the body to be observed. By this light irradiation, an image of the inside of the body to be observed is captured by the CCD 15 at the distal end, and the CCD 15 accumulates charges corresponding to the image. The reading of the stored charge is performed by C
The control is performed by a control pulse from the CD drive circuit 18. However, when the electronic shutter function is used, the timing of accumulation or readout may be changed by the control pulse, thereby changing the charge accumulation time and adjusting the exposure amount. it can. Thus, in the embodiment, under the control of the all-pixel reading pulse generating circuit 19, the accumulated data of all the pixels of the CCD 15 obtained by one exposure is read. That is, as shown in FIG. 4C, based on the exposure of the light output Pn-1 in FIG. 4B, n-1 odd (ODD) line data and even (EVEN) line data are output from the CCD 15. The odd line data is read out in order.
The (E) write (write enable) signal causes the first
The even line data stored in the memory 22 is shown in FIG.
Is stored in the second memory 23 by the write signal. Also, the data of the odd and even lines are read out in the order of the optical outputs Pn, Pn + 1... And stored in the memories 22 and 23. Next, the data in the memories 22 and 23 are pixel-mixed by the mixing circuit 24, and as shown in FIG. , Odd-numbered field data mixed with a combination of n-2 even-numbered line data and n-1 odd-numbered line data, and odd-numbered line data between n-1 Field signals are sequentially formed, such as odd (Odd) field signals mixed by the combination of even line data. These field signals are subjected to color image processing and temporarily stored in the third memory 29 and the fourth memory 30.
The outputs 9 and 30 are alternately output to the monitor by the switching circuit 31 and displayed by interlaced scanning. Therefore, in this example, a moving image is displayed as an image in which a part of the image data obtained at the next exposure is mixed.
/ 2, and even if there is blurring or movement during 1/60 seconds, the effect is small. On the other hand, for a still image, an image is displayed using only the data at the same exposure, and the memory control circuit 25 (a CPU or the like (not shown)) shown in FIG.
The control operation of FIG. 3 is performed. That is, this control is performed as shown in FIG.
Each operation is set to be executed when the O / E signal of (A) falls.
It is determined whether or not 7 is pressed (ON). If it is pressed, the write enable of the first memory 22 and the second memory 23 is prohibited in step 102. For example, if the freeze switch 17 is turned on at the time point Q shown in FIG. 4D, the field O / E signal is at the falling time (A1) at this time. At the time (A2), the memories 22, 23
Is prohibited [FIGS. 4E and 4F]. Therefore, in the state where the n odd line data obtained by the optical output Pn is written in the first memory 22 and the n even line data is written in the other second memory 23, the next data is written. Not done. As a result, as shown in FIG. 4 (G), an odd (Odd) field signal and an even (Even) field signal composed of odd-numbered and even-numbered n line data are sequentially read out, and these field signals are interlaced. Is displayed as a still image. In this manner, the combination of the field images at different times is prohibited, and a still image is displayed based on the data of all the pixels at the same exposure. It is possible to do. Even if the freeze switch 17 is pressed at another time,
After the odd line data and the even line data of the same number (n-1, n + 1, etc.) are always written, the next write is prohibited. In the above embodiment, as described above, the electronic shutter function can be used according to the brightness of the inside of the object to be observed. According to the present invention, the effect of this electronic shutter function is further enhanced. There is also an advantage. In other words, the screen becomes brighter when the tip approaches the affected part, etc.
Although the image quality can be improved by shortening the accumulation time in the CCD 15 by the electronic shutter function, the conventional method forms an image based on a video signal obtained by two exposures. Movement between exposures and blurring will affect image quality. However, in the present invention, since a still image is formed based on a video signal obtained by one exposure, the effect of shortening this one exposure time, that is, the signal accumulation time, directly appears, and the exposure time is reduced. There is an advantage that image quality improvement by shortening becomes remarkable. Also, in consideration of burns and the like of the affected part, it is not preferable to apply strong illumination light from the distal end of the endoscope to the affected part for a long time, and the intensity of the illumination light is limited to some extent. become. However, according to the present invention, the light output is reduced by half compared with the conventional case, so that the illumination light intensity can be increased, and there is an advantage that a more easily viewable image can be formed. As described above, according to the present invention,
While using the light blocking means, for the image signal obtained by the image sensor in one exposure, the image signal of either the odd or even line is read first, and then the image signals of the remaining lines are read. Control and temporarily store the odd-line data and the even-line data in the memory, and then read by mixing the pixels, thereby forming a moving image.
When a still image is formed, only the odd-line and even-line image signals obtained at the same exposure are stored in the memory, so that the image pickup device can be formed by one exposure without increasing the clock frequency. Can be read out, and the image quality can be improved particularly in a still image. Further, there is an advantage that the effect of the electronic shutter function can be sufficiently exerted, and the image quality can be further improved by increasing the illumination light intensity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a circuit configuration of an all-pixel readout electronic endoscope apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing image data read from the CCD of FIG. 1 to a mixing circuit. FIG. 3 is a flowchart illustrating a memory control operation in a first memory and a second memory of FIG. 1; FIG. 4 is an explanatory diagram showing main operations of the embodiment. 5A and 5B show a configuration of a conventional CCD, FIG. 5A is a configuration diagram of a color filter, and FIG. 5B is an explanatory diagram of mixed reading from the CCD. FIG. 6 is an explanatory diagram showing an operation in a conventional CCD. [Description of Signs] 1,15: CCD (image pickup device), 10: electronic endoscope, 11: connector circuit, 12: processor device, 13: light source device, 17: freeze switch, 18: CCD drive circuit, 19 ... all-pixel readout pulse generation circuit, 22, 23, 29, 30 ... memory, 24 ... mixing circuit, 25, 32 ... memory control circuit, 35 ... light source, 36 ... optical chopper.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-191822 (JP, A) JP-A-8-79791 (JP, A) JP-A-58-121873 (JP, A) JP-A-58-19783 117776 (JP, A) JP-A-9-90244 (JP, A) JP-A-9-93495 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1/00-1 / 32 G02B 23/24-23/26 H04N 7/18

Claims (1)

(57) [Claims] 1. A plurality of color filters are arranged in pixel units.
An image sensor,To form moving images and still images, Once with the image sensor
Of the image signal accumulated for each pixel by the exposure of
To read the image signal of either the odd or even line
And then control to read the image signal of the remaining lines
An image sensor driving circuit, When the image signal is read out by the image sensor driving circuit, a predetermined
So that pixel signals are not accumulated in the image sensor at the time
Light blocking means for blocking illumination light; The image signal of the odd line obtained from the image sensor and
A memory for storing image signals of the even lines andControls writing and reading of this memory to form a still image
The odd lines and even lines obtained during the same exposure.
Writing is prohibited so that only the image signal
A memory control circuit that controls The odd and even lines read from this memory
Image signals are mixed to form a simultaneous image signal.
And a combined circuit, Based on the pixel mixing signal output from this mixing circuitMovement
Image and still imageForm a field imageAnd this still
As for the image, the frame image is
FormAll-pixel readout type electronic endoscope apparatus.