JP3425511B2 - All-pixel readout electronic endoscope - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-pixel readout type electronic endoscope apparatus, and more particularly to a method for reading out all pixels of an image stored in an image pickup device by one exposure. The present invention relates to a configuration for an endoscope apparatus that forms an image of high quality. 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, the quality of the moving image or still image displayed on the display (including the color shift) will be reduced. was there. 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. Further, conventionally, it has 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 has as its object to read all pixels obtained by an image pickup device by one exposure without increasing the clock frequency. Another object of the present invention is to provide an all-pixel readout type electronic endoscope apparatus capable of improving the image quality of moving images and still images. In order to achieve the above object, an all-pixel readout type electronic endoscope apparatus according to the present invention comprises: an image pickup device in which a plurality of color filters are arranged in pixel units; With respect to the image signal accumulated for each pixel by one exposure with this image sensor, an image signal of an odd-numbered or even-numbered line is read out first, and then the image signals of the remaining lines are read out. An element driving circuit, light blocking means for blocking illumination light so that pixel signals are not accumulated in the image sensor at a predetermined time when an image signal is read out by the image sensor driving circuit, and a light blocking means obtained from the image sensor. A memory for storing the odd-numbered line image signal and the even-numbered line image signal; and delaying the even-numbered or odd-numbered line image signal previously stored in the memory by one field period . And a mixing circuit for mixing the pixel signals of the odd-numbered lines and the even-numbered lines read from each of the memories at the same exposure time to form an image signal. A field image is formed on the basis of the pixel mixture signal output from. According to the above configuration, for example, the first 1 /
The charge accumulated by exposure (exposure time is arbitrary) within a period of 60 seconds (vertical synchronization period) is equal to the charge accumulated in the second period (1/6
At 0 seconds), the odd lines of the image sensor (CCD) are read (read from the transfer line), and the remaining even lines are read during the third (at the next exposure) period. 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 odd-numbered line and even-numbered line video signals are respectively stored in the memory. The first stored video signal, for example, the odd-numbered line video signal is further stored in the delay memory, and Delayed by one field period of seconds. As a result, all the signals of both lines obtained at the same exposure can be read from each memory at the same time. Then, after the data of each line is read simultaneously, the pixels are mixed by the mixing circuit. That is, a pixel mixed signal is formed by the same method as the above color difference line sequential mixed reading method, a video signal of odd field data and an even field data is formed, and an image is displayed based on the video signal. Therefore, one frame image is formed based on signals of all pixels obtained by one exposure, and a high-quality image can be displayed. FIG. 1 shows a circuit configuration of an all-pixel readout type electronic endoscope apparatus as an example of an embodiment. As shown, the electronic endoscope apparatus is 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. The connector section circuit 11 includes 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. Also, an A / D converter 21 for inputting the output signal of the CCD 15, for example, a first memory 22-1 for storing the odd line image data, a second memory 23 for storing the even line image data, A mixing circuit 24 and a memory control circuit 25 are provided. That is, the CCD 15
The video signal output from the memory control circuit 2 is not output by mixing two lines as in the related art.
Based on the control of 5, the video signals of the odd lines and the video signals of the even lines are temporarily stored in the respective memories 22 and 23. In the subsequent stage of the first memory 22-1, the delay memory 22 for storing the image signal of the first memory 22-1 as it is and delaying the readout timing by 1/60 second. -2 is provided. According to the delay memory 22-2, although the details will be described later, the memory 23
At the same time, the data of the odd and even lines obtained at the same exposure can be stored for the same period for reading out the data of two fields, thereby displaying a moving image or the like based on all pixel data at the same exposure. Is possible. Thereafter, the mixing circuit 24 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 mixing readout system. 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. The data of the odd lines (1, 3, 5,...) Of the CCD 15 are stored in the first memory 22-1 (delay memory 22-2) of FIG.
.. (Line) are stored in the second memory 23 of FIG. The data in these memories 22-2 and 23 are
By the mixing circuit 24, pixel mixing is performed between the lines in FIG. 2B and FIG. 2C, and as shown in FIG.
0 line + 1 line, 2 line + 3 line, 4 line +
.. Are 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 ...
Is output as even field data. The odd number of the lines of the CCD 15 is distinguished as ODD, the even number is identified as EVEN, the odd number of the field to be interlaced is Odd, and the 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. 3A, the field O (Odd) / E (Eve)
n) As the signal, a timing signal for forming a one-field image in 1/60 second as in the conventional apparatus is used.
Correspondingly, the optical chopper 36 is set to 1/30
By making one rotation per second, Pn-1 and Pn-1 in FIG.
As shown by n and Pn + 1, light is repeatedly output for a period of 1/60 seconds while sandwiching a light blocking state of 1/60 seconds. 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. After that, 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. 3C, based on the exposure of the light output Pn-1 of FIG. 3B, 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 first (D) write (write enable) signal causes the first
The even line data stored in the memory 22-1 is shown in FIG.
The data is stored in the second memory 23 by the write signal (F). The odd line data in the first memory 22-1 is written in the same manner as in FIG. (F), which is delayed by 1/60 second from the signal in FIG. (D), as shown in FIG. The signal is stored in the delay memory 22-2.
Thus, the data of the odd and even lines are read out in the order of the optical outputs Pn, Pn + 1,... And written into the memories 22-1, 22-2, and 23, and such write / read control is performed. Is the memory control circuit 2 of FIG.
5 is performed. Next, the data in the memories 22-2 and 23 are pixel-mixed by the mixing circuit 24, and as shown in FIG. At the same exposure time, an odd (Odd) field signal and an even (Even) field signal mixed and processed with a combination of even-numbered line data, and similarly an Odd field signal and an Even field signal mixed and processed with n-1 pieces of line data. Odd and even field signals are obtained based on the obtained image data. Considering the case where the delay memory 22-2 is not used, as shown in the lower part of FIG. 3G, the mixing circuit 24 outputs the n-2 (th) After the odd field signal mixed with the odd and even line data, the even field signal mixed with the combination of the n-2 even line data and the n-1 odd line data, and the odd and even n-1 Next to the Odd field signal mixed with the line data, an even field signal mixed with a combination of n-1 even line data and n odd line data, etc. Is output. Therefore, the delay memory 22-2 of the present invention eliminates the state where the data from different exposures are mixed in the field image or the frame image as described above. Then, these field signals are subjected to color image processing, and the third memory 29 and the fourth memory 3 are processed.
0, and the outputs of these memories 29 and 30 are alternately output to the monitor by the switching circuit 31 and displayed as images by interlaced scanning. Therefore, in this example, a moving image is displayed on the monitor based on all pixel data (odd and even field data) obtained at the same exposure, and a high-quality image can be obtained. Therefore, even if the endoscope itself shakes or the subject moves for 1/60 second, it is possible to observe a clear image with a small influence. FIG. 4 shows a freeze operation for forming a still image, and the memory control circuit 25 shown in FIG.
(It may be a CPU or the like).
The control operation is set to be executed when the E signal falls. For example, if the freeze operation is turned on by the freeze switch 17 at the time Q shown in FIG. 4B, the field O / E signal is at the falling time (A1) at this time. At the time (A2), the delay memory 22-2 (may be the first memory) and the second memory 2
3 is prohibited [FIGS. 4C and 4D]. Then, the n odd line data obtained by the optical output Pn is written in the delay memory 22-2, and the n even line data is also written in the other second memory 23. Is not written. As a result, as shown in FIG. 4 (E), only the odd (Odd) field signal and the even (Even) field signal comprising the odd and even line data of n are continuously read out, and these field signals are read out. Are displayed as still images by interlaced scanning. Therefore, even in the case of a still image, a clear image can be obtained based on all pixel data obtained at the same exposure. In the above embodiment, as described above, the electronic shutter function can be used in accordance with the brightness of the object to be observed. According to the present invention, the effect of the electronic shutter function can be reduced. There is an advantage of further increasing.
That is, the screen becomes brighter when the leading end approaches the affected part, and the like, so that the accumulation time in the CCD 15 can be shortened by the electronic shutter function to improve the image quality.
In the conventional method, an image is formed based on a video signal obtained by two exposures. Therefore, if there is movement between two exposures and there is a blur, the image quality is affected. 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 the image quality is significantly improved by shortening the length. Further, in consideration of burns 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,
With the use of the light blocking means, for the image signal obtained by the image sensor in one exposure, first, the image signal of either the odd or even line is read out, and then the image signals of the remaining lines are read out (total At the same time as the pixel reading, the odd line data and the even line data are controlled so as to be stored in the memory at the same timing while using the delay memory, and thereafter the pixels are read out in a mixed state. without increasing the can read all pixels obtained during the same exposure, the all pixels moving and still images can be formed on the basis of the data, it is possible to observe the image of the clear high-quality . Further, there is an advantage that the effect of the electronic shutter function can be sufficiently exhibited, and the image quality can be further improved by increasing the intensity of the illumination light.

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 an explanatory diagram showing a main image forming operation of the embodiment. FIG. 4 is an explanatory diagram showing a still image forming operation in 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, 22-1, 23, 29, 30 ... memory, 22-2 ... delay memory, 24 ... mixing circuit, 25, 32 ... memory control circuit, 35 ... light source, 36 ... optical chopper.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-259833 (JP, A) JP-A-6-125871 (JP, A) JP-A-2-88026 (JP, A) Patent 3115216 (JP, A) B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 1/00-1/32 G02B 23/24-23/26 H04N 7/18

Claims (1)

(57) [Claims 1] First, an image sensor in which a plurality of color filters are arranged in pixel units and an image signal accumulated for each pixel by one exposure with this image sensor are first described. An image sensor driving circuit that reads out an image signal of either an odd or an even line, and then controls to read image signals of the remaining lines; and at a predetermined time when the image signal is read out by the image sensor driving circuit. Light blocking means for blocking illumination light so that pixel signals are not accumulated in the imaging device; memory for storing the odd-line image signal and the even-line image signal obtained from the imaging device; and the memory a delay memory for delaying by one field period an image signal of the previous said even or odd stored in the line within the above time the same exposure read out from the memory of the A mixing circuit for forming an image signal by mixing pixel signals of several lines and the even lines, and an all-pixel read-out type for forming a field image based on a pixel mixed signal output from the mixing circuit Electronic endoscope device.