JPH09130666A - Electronic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce flicker by storing image signals for one frame in a memory while dividing them into odd-numbered field image signals and even-numbered ones at 1st time intervals, reading the odd-numbered and even-numbered image signals from this memory respectively twice at 2nd time intervals and providing image signals for successive scanning system. SOLUTION: Concerning subjects in respective colors formed on the photodetecting plane of a CCD image sensor 12, image processing is performed by a process circuit 22, afterwards, A/D conversion 24 is executed and these images are written in the respective storage areas of a memory 28 at the 1st time intervals. Then, the image signals are read from the odd-numbered and even-numbered field memory areas of the memory 28 by a timing generator 26. The image signals for successive scanning system for two frames are prepared by reading the odd-numbered and even-numbered field image signals from this memory 28 respectively twice at the 2nd time intervals. Thus, since an electronic endoscope enables video reproduction in the successive scanning system, the generation of flicker with video reproduction due to conventional PAL system is reduced or canceled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope,
More specifically, it relates to improvement of a video display processing unit of an electronic endoscope.

[0002]

2. Description of the Related Art Generally, an electronic endoscope includes a scope consisting of a flexible conduit, and a solid-state image pickup device such as a CCD (charge coupled device) image sensor is provided at the tip of the scope. The image sensor is combined with an objective lens system, and a subject image captured by this objective lens system is formed on the light receiving surface of the solid-state imaging device. In addition, an optical guide consisting of an optical fiber bundle is inserted into the scope, the end face of the tip is located at the tip of the scope of the electronic endoscope, and the other end is connected to the light source. When the scope is inserted into the patient's body cavity, the front of the objective lens system on the tip side is illuminated by the light emitted from the end face of the tip part of the light guide to search for or observe the lesion in the patient's body cavity. To do.

The solid-state image pickup device converts a subject image formed on its light receiving surface into an analog image signal for one frame, and the analog image signal is sequentially read by clock pulses at predetermined time intervals. The analog image signal read from the solid-state imaging device is converted into a digital image signal after being subjected to predetermined image processing, and then the digital image signal is divided into odd field data and even field data, and both field data Are temporarily stored in the odd field memory area and the even field memory area, respectively. Next, the odd field data read from the odd field memory area is converted into an analog image signal, then passed through a low-pass filter, amplified, and then sent to a monitor device, where the above-mentioned subject image is horizontally scanned by odd scan lines. Reproduced as an image. Subsequently, the even field data read from the even field memory area is also converted into an analog image signal, then passed through a low pass filter, amplified, and sent to a monitor device, where the above-mentioned subject image is horizontally scanned by even scan lines. Reproduced as an image. Thus, the monitor device can obtain a horizontal scanning image for one frame. Such an image scanning system is generally called an interlace scanning system and is adopted in a normal television receiver.

The electronic endoscope as described above is usually combined with a color monitor device so as to perform color display. In this case, since the number of pixels of a solid-state imaging device such as a CCD image sensor used in an electronic endoscope is smaller than that of a normal one, a so-called frame sequential method is adopted. That is, the light guide extending from the light source is a rotary type
An RGB color filter is interposed, and red light, green light, and blue light are sequentially emitted from the end face of the tip of the light guide, and the subject image is a red, green, and blue light receiving surface of the CCD image sensor. Then, the red image signal, the green image signal and the blue image signal are read out at predetermined time intervals. Next, the individual color image signals are processed in the same manner as described above, and the subject image is reproduced as a full-color image on the color monitor device based on the processed image signals.

[0005]

In the electronic endoscope described above, the PAL method is usually adopted in Europe.
In the L method, an image of 25 frames per second is reproduced on the monitor device by the interlaced scanning (interlaced scanning) method. It has been pointed out that as a problem of such an interlaced scanning system, flicker on the display screen of a monitor device is inevitably accompanied by so-called flicker. Although such flicker itself is not a problem when the monitor is observed for a short period of time, it causes eye fatigue for a doctor who requires a long period of observation, which interferes with normal diagnosis. As is well known, it is pointed out that the resolution in the vertical direction is deteriorated as a peculiar drawback of the interlaced scanning method. The problem is that it makes proper medical examination difficult.

Accordingly, an object of the present invention is to provide an electronic endoscope as described above, which is constructed so as to eliminate the flicker problem and solve the vertical resolution deterioration problem. It is to be.

[0007]

An electronic endoscope according to a first aspect of the present invention is a solid-state image pickup device and an image signal for one frame read from the solid-state image pickup device in an odd field at a first time interval. A memory means for temporarily storing the image signal and the even field image signal separately, and the odd field image signal and the even field image signal are read from the memory means twice at a second time interval and sequentially. It is provided with a first image signal creating means for creating an image signal for two frames for the scanning method.

Preferably, in the electronic endoscope according to the first aspect of the present invention, the odd-field image signal and the even-field image signal are read alternately from the memory means at the first time interval and used for the interlaced scanning method. A second image signal creating means for creating an image signal for one frame is provided.

In the first aspect of the present invention, the first time interval and the second time interval may be equal to each other, or the second time interval may be shorter than the first time interval.

Further, in the first aspect, the first image signal producing means may produce the same contents as the image signals for two frames for the progressive scanning system, or two frames for the progressive scanning system. Minute image signals having different contents may be created by interpolation processing.

In the first aspect of the present invention, the image signal for one frame read from the solid-state image pickup device is preferably a color image signal obtained by a frame sequential method.

The electronic endoscope according to the second aspect of the present invention is a solid-state image pickup device, and an image signal for one frame read from the solid-state image pickup device at an first time interval with an odd field image signal and an even field image. A memory means for temporarily storing the divided signals and the odd-numbered field image signal and the even-numbered field image signal twice from the memory means at a second time interval shorter than the first time interval. And a first image signal creating means for creating an image signal for two frames for the progressive scanning method.

Preferably, in the electronic endoscope according to the second aspect of the present invention, an odd field image signal and an even field image signal are read alternately from the memory means at a first time interval and used for the interlaced scanning system. A second image signal creating means for creating an image signal for one frame is provided.

Further, in the second aspect of the present invention, the first image signal producing means may produce the same contents as the image signals for two frames for the progressive scanning system. In this case, , The first image signal for each predetermined number of readings of the odd-numbered field image signal and the even-numbered field image signal from the memory means according to the difference between the first time interval and the second time interval. In addition to the image signals for two frames for the progressive scanning method, the creating means further creates an image signal for at least one frame having the same content.

On the other hand, in the second aspect of the present invention, the first image signal producing means may produce two frames of image signals for the progressive scanning system having different contents by interpolation processing. In this case, the first time interval and the second
According to the difference between the time interval of the first image signal generating means and the even field image signal from the memory means, the first image signal generating means for the sequential scanning method is provided every two times. In addition to the image signals for the frames, an image signal for at least one frame is further created by interpolation processing.

Also in the second aspect of the present invention, preferably, the image signal for one frame read from the solid-state image pickup device is a color image signal obtained by the frame sequential method.

In the electronic endoscope according to the third aspect of the present invention, a solid-state imaging device and an image signal for one frame read from the solid-state imaging device are selected from a first time interval and a second time interval. Memory means for temporarily storing the odd field image signal and the even field image signal separately at any one of the selected time intervals; and the odd field from the memory means when the first time interval is selected. A first image signal creating means for alternately reading the image signal and the even field image signal once at a first time interval to create an image signal for one frame for the interlaced scanning method; When the time interval is selected, the odd field image signal and the even field image signal are read twice from the memory means at the second time interval, respectively, and the two-frame for the sequential scanning method is read. Comprising and a second image signal generating means for generating an image signal of the beam component. Preferably,
An image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method.

An electronic endoscope according to a fourth aspect of the present invention is a solid-state image pickup device, and an image signal for one frame read from the solid-state image pickup device is read with an odd field image signal and an even field image at a first time interval. Memory means for temporarily storing the divided signals and the odd-numbered field image signal and the even-numbered field image signal from the memory means twice at a first time interval and two frames for a progressive scanning method. Minute image signals, first image signal creating means and the memory means alternately read the odd field image signal and the even field image signal at a second time interval longer than the first time interval. A second image signal creating means for creating an image signal for one frame for the interlaced scanning method is provided. Preferably, the image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method.

[0019]

Next, various embodiments of an electronic endoscope according to the present invention will be described with reference to the accompanying drawings.
Referring to FIG. 1, a first embodiment of an electronic endoscope according to the present invention is illustrated as a block diagram. The electronic endoscope includes a scope 10 made of a flexible conduit, and a CCD image sensor 12 as a solid-state image pickup device is provided at the tip of the scope 10. The CCD image sensor 12 is an objective lens system (not shown). The subject image captured by this objective lens system is formed on the light receiving surface of the solid-state imaging device. Further, a light guide 14 formed of an optical fiber bundle is inserted into the scope 10, the end surface of the tip portion thereof extends to the end surface on the tip side of the scope 10, and the other end portion thereof is connected to the light source 16.
The electronic endoscope according to the present invention can be combined with the color monitor device 18 to perform color display. In the embodiment of the present invention, a so-called frame sequential method is adopted to read a color image. That is, the rotary RGB color filter 20 is interposed in the light guide 14 extending from the light source 16, and the subject is sequentially illuminated with red light, green light, and blue light. The rotary RGB color filter 2
0 is rotated 25 times per second like the conventional PAL system, and the number of horizontal scanning lines of one frame image reproduced by the color monitor 18 is 625 as in the conventional PAL system.
It is a book.

The rotary RGB color filter 20 is composed of a disc element, which is divided into six sector areas from the center to the outer periphery, and three sector areas are arranged every other one of them. The area is a light shielding area, and the other three sector areas are a red filter, a green filter and a blue filter, respectively. When the rotary RGB color filter 20 is rotated 25 times per second, the time required for one rotation is 40 ms, and the illumination time for each color filter is approximately 20/3 ms. In short, as shown in the time chart of FIG. 2, red light is emitted from the end face of the tip of the light guide 14.
R, green light G, and blue light B are sequentially emitted for about 20/3 ms during every 40 ms (1/25 sec), and the object is red light R,
CCD image sensor 1 with green light G and blue light B
Images are sequentially formed on the two light receiving surfaces. CCD image sensor 12
Converts the object image of each color imaged on its light-receiving surface into an analog image signal for one frame, and the analog image signal of each color is illuminated for each color (approx. It is read from the CCD image sensor 12 over time (eg 20/3 ms). The reading of the analog image signal from the CCD image sensor 12 is performed by a well-known CCD driver circuit (not shown), and the analog image signal of each color is subjected to predetermined image processing such as gamma correction in the CCD process circuit 22 and then analog / image Digital (A
/ D) Converted into a digital image signal by the converter 24. Strictly speaking, the output power of each color from the color filter 20 and the CCD image sensor 12
Due to the different spectral sensitivity characteristics, the illumination time by red light R, green light G and blue light B is slightly different, but the reading of each color image signal from the CCD image sensor 12 is within the same shielding time. Done in.

The digital image signal of each color is written in each memory area of the memory 28 by the timing generator 26. That is, as shown in FIG. 2, the red image signal is divided into odd field data OR (1) and even field data ER (1), which are alternately written in the field memory areas R1 and R2, respectively, and the green image Signal is also odd field data OG (1) and even field data
Field memory area divided into EG (1)
Alternately written to G1 and G2, the blue image signal is also odd field data OB (1) and even field data.
Field memory area B1 divided into EB (1)
And written to B2. Image signals to each field memory area (odd or even field data)
For the frequency of the write clock pulse of the conventional PAL
It is similar to the method.

The timing generator 2 also reads the image signal from each of the odd and even field memory areas (R1, R2, G1, G2, B1, B2) of the memory 28.
6 but the read-out aspect is conventional PAL
Different from the method. That is, in the first embodiment of the present invention, as described in detail below, the same field data is read twice from each field memory area, and two image signals for one frame having the same content are created. It In the following description, the frequency of the read clock pulse of the field data from each field memory area is the same as the frequency of the write clock pulse of the field data to the field memory area, but the frequency is not the same for both. It is not necessary, for example, to set the frequency of the read clock pulse to twice the frequency of the write clock pulse, and to read the field data from the field memory area when the writing of the field data to the respective field memory areas is completed. it can.

First, as shown in the time chart of FIG. 3, the digital image data L1 corresponding to the first horizontal scanning line (1H line) written therein is read from the odd field memory region R1 and the digital image data L1 is read out. Image data L1
Is an effective horizontal scanning line for one frame reproduced by the monitor device 18 in the interlaced scanning method (in the case of the PAL method,
Of the 625 lines, 575 are reproduced by the monitor device 18) and correspond to the first horizontal scanning line. Next, digital image data L2 corresponding to the first horizontal scanning line written therein is read from the even field memory area R2, and this digital image data L2 is reproduced in the monitor device 18 by the interlaced scanning method in one frame. Of the effective horizontal scanning lines corresponding to the second horizontal scanning line. Next, when digital image data L3, L4, L5, L6, L7, L8, L9, ... All red odd field data OR (1) are read from the field memory area R1 and all red even field data ER (1) are read from the field memory area R2. That is, the red image signals [OR (1), ER (1)] for one frame can be obtained from both the field memory areas R1 and R2. Then, from the field memory areas R1 and R2, the red odd field data OR of the same contents is ORed.
(1) and the red even field data ER (1) are read, and the red image signal [OR (1), ER (1)] for one frame with the same content is obtained again from both field memory areas R1 and R2. To be In short, the field memory areas R1 and R2
Will output a red image signal for one frame of the same content twice. Similarly, one frame worth of green image signals [OG (1), EG (1)] from the field memory areas G1 and G2, and one frame content from the field memory areas B1 and B2. Blue image signal [O
B (1), EB (1)] are read twice each.

When the reading of the field data having the same content from each of the two field memory areas is completed twice, the same writing and reading are repeated every 40 ms thereafter, and the odd and even field memory areas (R1, R1 R2; G1, G2; B1, B2) from one frame of red image signals [OR (2), ER (2)], [OR (3), ER (3)], ... [OR
(n), ER (n)] ..., Green image signal for one frame [OG (2), E
G (2)], [OG (3), EG (3)],… [OG (n) + EG (n)]… and one frame of blue image signal [OB (2), EB (2)] , [OB (3), EB
(3)], ... [OB (n), EB (n)] ... are sequentially read twice each, and the full-color image signals Z (1), Z ( 2), Z (3), ... Z (n) ... is 40ms
You get 2 for each.

Here, focusing on the full-color image signals Z (1), Z (2) and Z (3) for one frame, the full-color digital signal for each one frame can be expressed by the following equation. it can. Z (1) = [[OR (1), ER (1)], [OG (1), EG (1)], [OB (1), EB (1)]] Z (2) = [[OR (2), ER (2)], [OG (2), EG (2)], [OB (2), EB (2)]] Z (3) = [[OR (3), ER (3) ], [OG (3), EG (3)], [OB (3), EB (3)]] Also, full-color image signal X (1) for one odd field,
If X (2), X (3), ... And full-color image signals for one even field Y (1), Y (2), Y (3), ... Can be expressed as X (1) = [OR (1), OG (1), OB (1)]: Y (1) = [ER (1), EG (1), EB (1)] X (2) = [OR (2), OG (2), OB (2)]: Y (2) = [ER (2), EG (2), EB (2)] X (3) = [OR (3), OG (3 ), OB (3)]: Y (3) = [ER (3), EG (3), EB (3)] That is, each full-frame image signal Z (1), Z (2) for one frame.
And Z (3) can be expressed as follows. Z (1) = [X (1), Y (1)] Z (2) = [X (2), Y (2)] Z (3) = [X (3), Y (3)]

In the time chart of FIG. 4, writing of a full-color image signal for one odd field into the odd field memory areas R1, G1 and B1 and one even field for the even field memory areas R2, G2 and B2. The relationship between the writing of full-color image signals and the reading of full-frame image signals for one frame from these field memory areas is shown. As is clear from the figure, the reading is performed twice for each writing of the full-color image signal to the odd-numbered and even-numbered field memory areas. That is, the full-color image signal for one frame having the same content is output from the memory 28 twice every 40 ms.

The timing generator 26 not only writes an image signal to and reads an image signal from each field memory area, but also creates various timing signals such as a horizontal synchronizing signal and a vertical synchronizing signal. In order to generate such a timing signal, the timing generator 26 is provided with a horizontal counter 30 and a vertical counter 32 as shown in FIG. 5, and decoders 34 and 36 are connected to these counters 30 and 32, respectively. .

The horizontal counter 30 counts clock pulses for reading image signals from the odd and even field memory areas (R1, R2; G1, G2; B1, B2) of each color,
When the count number reaches a predetermined set value, the horizontal count is reset. The set value corresponds to the number of clock pulses (that is, the number of pixels included in one horizontal scanning line) required when reading the image signal of one horizontal scanning line read from each field memory area. As shown in the time chart of FIG. 6, each time the image signal of one horizontal scanning line segment (one horizontal scanning period) is read from each field memory area, a pulse is output from the horizontal counter 30 to the decoder 34. It When the output pulse from the horizontal counter 30 is input to the decoder 34, a horizontal synchronizing signal or the like is output from the decoder 34, and the horizontal synchronizing signal or the like is added after the read image signal for one horizontal scanning line.

As is apparent from FIG. 5, the horizontal counter 3
The pulse output from 0 is also input to the vertical counter 32, the vertical counter 32 counts the input pulse, and when the count number reaches a predetermined set value, the vertical counter 32 is reset. There is. The set value is set to the total number of horizontal scanning lines (625 in the present embodiment) when the image of that color is reproduced by the monitor device 18 with the image signal for one frame obtained from the odd and even field memory areas of each color. Correspond. As shown in the time chart of FIG. 7, the image signal for one frame (vertical scanning period) is an odd and even field memory area (R1,
R2; G1, G2; B1, B2) each time a pulse is output from the vertical counter 32 to the decoder 36. The output pulse from the vertical counter 32 is the decoder 3
When it is input to 6, the decoder 36 outputs a vertical synchronizing signal or the like, which is added after the read image signal for one frame of each color.

A full-color image signal for one frame, which is sequentially output from the memory 28, is converted back into an analog image signal by a digital / analog (D / A) converter 38, then passed through a low pass filter (LPF) 40, and then an amplifier ( It is amplified by the AMP) 42 and output to the monitor device 18. Thus, in the monitor device 18, the image captured by the CCD image sensor 12 is reproduced by the progressive scanning method.

By the way, although it is desired to record an image picked up by an electronic endoscope on a video tape or the like, as described above, the image signal output from the memory 28 by the progressive scanning method is a conventional video. Recording / playback by a recording / playback device is usually impossible. This is because conventional video recording / playback devices are designed for interlaced scanning. Therefore, it is preferable that the electronic endoscope shown in FIG. 1 also be capable of selectively performing image reproduction in the PAL system (that is, the interlaced scanning system). In this case, as shown in FIG. 8, in addition to the horizontal counters 30 and 32 used in the sequential scanning system, the PA
The horizontal counter 44 and the vertical counter 46 necessary for reproducing in the L system may be provided in the timing generator 26, and the horizontal counter 44 and the vertical counter 46 are respectively used to generate the horizontal synchronizing signal and the vertical synchronizing signal. Connected to decoders 48 and 50. As the monitor device, a type that can be commonly used for the interlace scanning system and the progressive scanning system is known, and the monitor device 18 shown in FIG. 1 is of such type.

Referring to FIG. 9, an image projected on the display screen of the monitor device 18 based on the PAL system and the monitor device 1 based on the system according to the first embodiment of the present invention.
The image projected on the display screen 8 is shown as an example. As is clear from the figure, in the case of the PAL system, the video based on the full-color image signal X (n) for one odd field and the full-color image signal Y for one even field
While the image based on (n) is sequentially displayed every 40 ms to form a full-color image for one frame, in the case of the method according to the first embodiment of the present invention, one frame worth of Full-color image signal Z (n) = [X (n), Y (n)] is 40ms
Displayed twice each time. Thus, according to the first embodiment of the present invention, since an image of 50 frames per second can be obtained, the flicker problem associated with the conventional PAL method, that is, the flicker problem on the display screen of the monitor device 18 is greatly reduced. Can be reduced to.

Referring to FIG. 10, there is shown a second embodiment of the electronic endoscope according to the present invention, in which the same components as those of the electronic endoscope shown in FIG. 1 are the same. Reference numbers are used. In the electronic endoscope shown in FIG. 10, the capacity of the memory 28 is doubled as compared with that shown in FIG. That is, the memory 28 includes odd field memory areas R1, G1 and B1 and even field memory areas R2 and G2.
In addition to red and odd field memory areas R3 and R4, green odd field memory area G3 and even field memory area G4, blue odd field memory area B3 and even field memory Area B4 is prepared.

Also in the second embodiment, the rotation frequency (25 Hz) of the rotary RGB color filter 20 and the image sensor 1 are used.
The reading of the analog image signal from 2 is the same as in the case of the first embodiment. In addition, the image sensor 12
The analog image signal of each color read from the CCD
Similar to the first embodiment, an analog / digital (A / D) converter 24 converts the image data into a digital image signal after receiving predetermined image processing such as gamma correction in the process circuit 22. Image signal memory 28
Writing to and reading of a digital image signal therefrom are different from those in the first embodiment.

More specifically, in the second embodiment, FIG.
As shown in the time chart of FIG. 1, first, the full-color image signal X (1) for one odd field and the full-color image signal Y (1) for one even field are stored in the odd field memory areas R1, G1 and B1 and the even field memory, respectively. Region R2,
After being written in G2 and B2, the next full-field image signal X (2) for one odd field and the full-color image signal Y (2) for one even field are respectively odd field memory areas R3, G3 and B3 and even. Field memory area R4, G4
And B4, and such writing is repeated every 40 ms, but the writing time to each field memory area is almost half the time, for example, 20 ms as compared with the case of the first embodiment. By doubling the frequency of the clock pulse for writing the image signal in each field memory area of the memory 28, the writing can be performed in about half the time of 40 ms. In short, in the second embodiment, the full-color image signal X (2n-1) for one odd field and the full-color image signal Y (2n-1) for one even field are each an odd field memory area.
R1, G1 and B1 and even field memory areas R2, G2 and B2 are written, and the full color image signal X (2n) for one odd field and the full color image signal Y (2n) for one even field are odd. Field memory area
R3, G3 and B3 and even field memory areas R4, G4 and B4 are written.

On the other hand, in the second embodiment, the reading of the full-color image signal for one frame from the memory 28 is performed 60 times per second. That is, about 100 / 3ms (1,000 / 30ms)
Full-color image signal Z (n) for one frame with the same content for each
Is read twice. More specifically, as is apparent from FIG. 11, the odd field memory areas R1, G1 and B1 are
Full-color image signal X (1) for one odd field written in and the full-color image signal Y for one even field written in even field memory areas R2, G2, and B2.
Based on (1) and, one frame of full-color image signal Z
(1) is read twice and then written into the odd field memory areas R3, G3 and B3. The full color image signal X (2) for one odd field and the even field memory area R
The full-color image signal Z (2) for one frame is read out twice based on the full-color image signal Y (2) for one even field written in 4, G4, and B4. Are sequentially repeated, but in the second embodiment, reading of the image signal Z (5n) for one frame is repeated four times. That is, the full-color image signal X (5) for one odd field written in the odd field memory areas R1, G1 and B1 and the even field memory area R
2, based on the full-color image signal Y (5) for one even field written in G2 and B2, the full-color image signal Z (5) for one frame is read four times and the next four times For odd field memory areas R3, G3 and
Full-color image signal X (10) for one odd field written in B3 and even field memory area R4, G4 and B4
Is performed based on the full-color image signal Y (10) for one even field written in According to such reading, the full-color image signal for 25 frames per second is written in the memory 28, but the full-color image signal for 60 frames per second is read therefrom.

A full-color image signal Z (n) for one frame which is sequentially output from the memory 28 at intervals of about 50 / 3ms (1,000 / 60ms).
Is converted back into an analog image signal by the D / A converter 38,
Next, after passing through a low pass filter (LPF) 40, an amplifier (AMP)
The signal is amplified by 42 and output to the monitor device 18. Thus, in the monitor device 18, the image captured by the CCD image sensor 12 is reproduced as an image signal for 60 frames per second by the progressive scanning method. As in the case of the first embodiment, it is preferable that the second embodiment also allows the image reproduction in the PAL system (that is, the interlaced scanning system) to be selectively performed.

Referring to FIG. 12, an image projected on the display screen of the monitor device 18 based on the PAL system and an image projected on the display screen of the monitor device 18 based on the system according to the second embodiment of the present invention. An image is shown as an example. As is clear from the figure, in the case of the PAL system, the video is reproduced based on the image signal of 25 frames per second, whereas in the second embodiment of the present invention, 60 frames per second. Since the video based on the minute image signal is reproduced by the progressive scanning method, the flicker problem associated with the conventional PAL method can be further improved as compared with the first embodiment of the present invention.

In the second embodiment described above, the full-color image signal Z (5n) for one frame is read four times, but the full-color image signal Z is read.
One full-frame image signal other than (5n) Z (5n-4), Z (5n-3), Z (5n-2), or Z (5n-1) is read four times each. It goes without saying that it may be done. In short, it is sufficient to obtain a full-color image signal for 60 frames per second for writing a full-color image signal for 25 frames per second.

Next, a third embodiment of the present invention will be described. The block diagram thereof is substantially the same as that of the second embodiment shown in FIG. 10, and the third embodiment and the second embodiment will be described.
The difference from the above embodiment is only the mode of reading a full-color image signal for one frame from the memory 28. In the third embodiment, the odd field memory areas R1, G1 and
Even if writing of the full-color image signal X (1) for one odd field to B1 and writing of the full-color image signal Y (1) for one even field to even field memory areas R2, G2 and B2 is completed, The full color image signal for one frame from 28 is not immediately read out, but writing of the full color image signal X (2) for one odd field to the odd field memory regions R3, G3 and B3 and the even field memory regions R4, G4. After the writing of the full-color image signal Y (2) for one even field to B4 and B4 is started, the reading of the full-color image signal for one frame from the memory 28 is started.

More specifically, as shown in the time chart of FIG. 13, writing the full-color image signal X (2) for one odd field to the odd field memory areas R3, G3 and B3 and the even field memory areas R4, G4. And, for example, 20 ms after the start of writing the full-color image signal Y (2) for one even field to B4, the full-color image signal X (1) for one odd field and the full-color image signal Y for one even field (1) and are read out to create the full-color image signal Z (1) for one frame, but the full-color image signal Z (2) for the next one frame is generated in the even field memory areas R2, G2 and Based on the full color image signal Y (1) for one even field read from B2 and the full color image signal X (2) for one odd field read from the odd field memory areas R3, G3 and B3. It is created have. The full color image signal Z (3) for the next one frame is the full color image signal X (2) for one odd field read from the odd field memory areas R3, G3 and B3 and the even field memory areas R4, G4 and It is created from the full-color image signal Y (2) for one even field read from B4. Further, the full-color image signal Z (4) for the next one frame is stored in the even field memory areas R4, G4 and
Full color image signal Y (2) for one even field read from B4 and odd field memory area R1, G1 and B1
It is created based on the full-color image signal X (3) for one odd field read from.

That is, the one-frame full-color image signal Z (n) read from the memory 28 having an odd number can be expressed by the following equation. Z (n) = [X (2n-1), Y (2n-1)] In addition, one frame of the full-color image signal Z (n) read from the memory 28 having an even number is expressed by the following formula. Can be written down. Z (n) = [X (2n), Y (2n)] However, in order to obtain a full color image signal of 60 frames per second for writing a full color image signal of 25 frames per second, Z (n) = [X (2n), Y (2n)] The reading of the full-color image signal for one frame having the number (5n) is repeated twice.

Similar to the second embodiment described above, about 50/3
The full-color image signal Z (n) for one frame, which is sequentially output from the memory 28 every ms (1,000 / 60 ms), is returned to the analog image signal by the D / A converter 38, and then the low-pass filter.
After passing through the (LPF) 40, it is amplified by the amplifier (AMP) 42 and output to the monitor device 18. Thus, the monitor device 18
Then, the image captured by the CCD image sensor 12 is reproduced by an image signal of 60 frames per second and by the progressive scanning method. As in the case of the first and second embodiments, it is preferable in the third embodiment as well to be able to selectively perform image reproduction in the PAL system (that is, the interlaced scanning system).

Referring to FIG. 14, an image projected on the display screen of the monitor device 18 based on the PAL system and an image projected on the display screen of the monitor device 18 based on the system according to the third embodiment of the present invention. An image is shown as an example. Also in the third embodiment of the present invention, since the video based on the image signal for 60 frames per second is reproduced by the sequential scanning, the flicker problem is remarkably improved as in the case of the second embodiment described above. However, what should be noted in the third embodiment of the present invention is that only every fifth video image based on the full-color image signal for one frame having the same content is repeated, and therefore, the smooth motion of the video image is obtained. This is an improvement over the second embodiment described above.

Referring to FIG. 15, there is shown a fourth embodiment of the electronic endoscope according to the present invention, in which the same components as those of the electronic endoscope shown in FIG. 1 are the same. Reference numbers are used. In the electronic endoscope shown in FIG. 15, the capacity of the memory 28 is further increased as compared with that shown in FIG. That is, in the memory 28, in addition to the odd field memory areas R1, G1, B1, R3, G3 and B3 and the even field memory areas R2, G2, B2, R4, G4 and B4,
Further, a red odd field memory area R5 and an even field memory area R6, a green odd field memory area G5 and an even field memory area G6, and a blue odd field memory area B5 and an even field memory area B6 are prepared. .

Also in the fourth embodiment, the rotation frequency (25 Hz) of the rotary RGB color filter 20 and the image sensor 1 are used.
The reading of the analog image signal from 2 is the same as in the case of the first embodiment. In addition, the image sensor 12
Firstly, the analog image signal of each color read from the CCD is converted into a digital image signal by the analog / digital (A / D) converter 24 after being subjected to predetermined image processing such as gamma correction in the CCD process circuit 22. However, the writing of the digital image signal to the memory 28 and the reading of the digital image signal from the memory 28 are different from those of the first, second and third embodiments.

More specifically, as shown in the time chart of FIG. 16, in the fourth embodiment, first, a full color image signal X (1) for one odd field and a full color image signal Y (1) for one even field. Are the odd field memory areas R1, G1 and B1 and the even field memory areas R2,
After being written in G2 and B2, the next full-field image signal X (2) for one odd field and the full-color image signal Y (2) for one even field are respectively odd field memory areas R3, G3 and B3 and even. Field memory area R4, G4
And the next full-color image signal X (3) for one odd field and the full-color image signal Y (3) for one even field are written to odd field memory areas R5, G5 and B5 and even field memory, respectively. Written to regions R6, G6 and B6, such sequential writes 120ms
It is repeated every time. That is, for the odd-numbered field full-color image signal X (3n-2) and the even-numbered field full-color image signal Y (3n-2), the odd-numbered field memory areas R1, G1, and B1 and the even-numbered field memory area, respectively. R2, G2, and B2 are written in the odd field memory area R3 for the full-color image signal X (3n-1) for one odd field and the full-color image signal Y (3n-1) for one even field. , G3 and B3 and even field memory areas R4, G4 and B4 are written to the full color image signal X (3n) for one odd field and the full color image signal Y (3n) for one even field, respectively. Odd field memory area R5, G5 and
B5 and even field memory areas R6, G6 and B6 are written. The writing of the image signal to each field memory area is performed in the same manner as in the first embodiment.

The fourth embodiment is directed to an improvement of the above-described second embodiment. Also in the fourth embodiment, as in the case of the second embodiment, when the full color image signal of 25 frames per second is written to the memory 28, the full color image signal of 60 frames per second is written from the memory 28. Reading is performed, and the full-color image signal for one frame having the same content is repeated twice. Therefore,
In this respect, the fourth embodiment can be said to be similar to the second embodiment, but in the second embodiment, in order to obtain a 60-frame full-color image signal from a 25-frame full-color image signal, While the fifth full-color image signal for one frame is repeatedly read four times, in the fourth embodiment, the full-color image signal for one frame having the same content is repeated four times. It is never read.

More specifically, first, the odd field memory areas R1, G1 and B1 and the even field memory areas R2, G2 are
From B2 and B2, the full-color image signal for one odd field X (1) = [OR (1), OG (1), OB (1)] and the full-color image signal for one even field Y (1) = [ OR (2), OG
(2), OB (2)] are read out, and these image signals X (1) and Y (1) are multiplied by the following coefficient in the multiplier 52. [OR (1), OG (1), OB (1)] × α1 = X (1) × α1 [OR (2), OG (2), OB (2)] × α2 = Y (1) × α2 At this time, the coefficients α1 and α2 are both set to 1 (6/6). The result obtained by the multiplier 52 is output to the adder 54, where the following calculation is performed to obtain the full-color image signal Z (1) for one frame. Z (1) = [[X (1) × 6/6 + 0], [Y (1) × 6/6 + 0]] = [X (1), Y (1)] This full-color image signal Z ( The reading of 1) is repeated twice.

Next, the odd field memory areas R1 and G1
And B1 and the even field memory areas R2, G2 and B2 respectively provide a full color image signal X (1) for one odd field and a full color image signal Y (1) for one even field.
Are read out again, and the image signals X (1) and Y (1) are multiplied by the following coefficients in the multiplier 52. X (1) × α1 Y (1) × α2 At this time, the coefficients α1 and α2 are both set to 1/6. On the other hand, from the odd field memory areas R3, G3 and B3 and the even field memory areas R4, G4 and B4, a full color image signal X (2) for one odd field and a full color image signal Y (2) for one even field, respectively. And are read out,
These image signals X (2) and Y (2) are multiplied by the following coefficient in the multiplier 52. X (2) × α3 Y (2) × α4 At this time, the coefficients α3 and α4 are both set to 5/6. The results obtained by the multiplier 52 are both output to the adder 54, where the following calculation is performed to obtain a full-color image signal Z (2) for one frame. Z (2) = [[X (1) × 1/6 + Y (1) × 1/6], [X (2) × 5/6 + Y (2) × 5/6]] This full-color image signal The reading of Z (2) is repeated twice.

Next, odd field memory areas R3 and G3
And B3 and the even field memory areas R4, G4 and B4 respectively provide a full color image signal X (2) for one odd field and a full color image signal Y (2) for one even field.
Are read out again, and the image signals X (2) and Y (2) are multiplied by the following coefficients in the multiplier 52. X (2) × α3 Y (2) × α4 At this time, the coefficients α3 and α4 are both set to 2/6. On the other hand, from the odd field memory areas R5, G5 and B5 and the even field memory areas R6, G6 and B6, the full color image signal X (3) for one odd field and the full color image signal Y (3) for one even field, respectively. And are read out,
These image signals X (3) and Y (3) are multiplied in the multiplier 52 by the following coefficients. X (3) × α5 Y (3) × α6 At this time, the coefficients α5 and α5 are both set to 4/6. The results obtained by the multiplier 52 are both output to the adder 54, where the following calculation is performed to obtain the full-color image signal Z (3) for one frame. Z (3) = [[X (2) × 2/6 + Y (2) × 2/6], [X (3) × 4/6 + Y (3) × 4/6]] This full-color image signal Reading Z (3) is repeated twice.

Subsequently, the odd field memory areas R5 and G5
And B5 and the even field memory areas R6, G6 and B6 respectively provide a full color image signal X (3) for one odd field and a full color image signal Y (3) for one even field.
Are read out again, and the image signals X (3) and Y (3) are multiplied by the following coefficients in the multiplier 52. X (3) × α5 Y (3) × α6 At this time, the coefficients α5 and α6 are both set to 3/6. On the other hand, from the odd field memory areas R1, G1 and B1 and the even field memory areas R2, G2 and B2, a full color image signal X (4) for one odd field and a full color image signal Y (4) for one even field, respectively. And are read out,
These image signals X (4) and Y (4) are multiplied in the multiplier 52 by the following coefficients. X (4) × α1 Y (4) × α2 At this time, the coefficients α1 and α2 are both set to 3/6. The results obtained by the multiplier 52 are both output to the adder 54, and the following calculation is performed there to obtain a full-color image signal Z (4) for one frame. Z (4) = [[X (3) × 3/6 + Y (3) × 3/6], [X (4) × 3/6 + Y (4) × 3/6]] This full-color image signal Reading Z (4) is repeated twice.

Next, a full-color image signal for one odd field is output from each of the odd field memory areas R1, G1 and B1 and the even field memory areas R2, G2 and B2.
X (4) and the even color field full-color image signal Y (4) are read out again, and these image signals X (4) and Y (4) are multiplied by the following coefficients in the multiplier 52. . X (4) × α1 Y (4) × α2 At this time, the coefficients α1 and α2 are both set to 4/6. On the other hand, from the odd field memory areas R3, G3 and B3 and the even field memory areas R4, G4 and B4, the full color image signal X (5) for one odd field and the full color image signal Y (5) for one even field, respectively. And are read out,
These image signals X (5) and Y (5) are multiplied by the following coefficients in the multiplier 52. X (5) × α3 Y (5) × α4 At this time, the coefficients α1 and α2 are 2/6. Multiplier 5
The results obtained in 2 are both output to the adder 54, and the following calculation is performed there to obtain a full-color image signal Z (5) for one frame. Z (5) = [[X (4) × 4/6 + Y (4) × 4/6], [X (5) × 2/6 + Y (5) × 2/6]] This full-color image signal Reading Z (5) is repeated twice.

Next, odd field memory areas R3 and G3
And B3 and the even field memory areas R4, G4 and B4 respectively provide a full color image signal X (5) for one odd field and a full color image signal Y (5) for one even field.
Are read out again, and the image signals X (5) and Y (5) are multiplied by the following coefficients in the multiplier 52. X (5) × α3 Y (5) × α4 At this time, the coefficients α1 and α2 are set to 5/6. On the other hand, from the odd-numbered field memory areas R5, G5 and B5 and the even-numbered field memory areas R6, G6 and B6, a full-color image signal X (6) for one odd field and a full-color image signal Y (6) for one even field, respectively. And are read out, and the image signals X (6) and Y (6) are multiplied by the following coefficients in the multiplier 52. X (6) × α5 Y (6) × α6 At this time, the coefficients α5 and α6 are set to 1/6. Multiplier 5
The results obtained in 2 are both output to the adder 54, and the following calculation is performed there to obtain the full-color image signal Z (6) for one frame. Z (6) = [[X (5) × 5/6 + Y (5) × 5/6], [X (6) × 1/6 + Y (6) × 1/6]] This full-color image signal Reading Z (5) is repeated twice.

When the reading of the full-color image signal Z (6) for one frame is completed twice, the odd field memory area R
5, G5 and B5 and even field memory areas R6, G6 and B6 read out full-color image signal X (6) for one odd field and full-color image signal Y (6) for one even field, respectively. , These full color image signals
The multiplier 52 multiplies X (6) and Y (6) by the following coefficients. X (6) × α5 Y (6) × α6 At this time, the coefficients α5 and α6 are both set to 1 (6/6). The results obtained by the multiplier 52 are both output to the adder 54,
Therefore, the following calculation is performed to obtain the full-color image signal Z (7) for one frame. Z (7) = [[X (6) × 6/6 + 0], [Y (6) × 6/6 + 0]] = [X (6), Y (6)] This full-color image signal Z ( The reading of 7) is repeated twice.

The full-color image signal Z (7) is created in the same manner as the full-color image signal Z (1), and the full-color image signal Z (n) for one frame after that is sequentially repeated by the above-mentioned read operation. Is obtained by

FIG. 17 shows a table of the interpolation processing of the full-color image signal Z (n) described above. FIG.
The symbol "*" in the table of 7 indicates the product. In short, in the fourth embodiment, one-sixth of each of continuous six full-frame image signals for one frame is taken out and the full-color image signal for one frame is interpolated.
5th full-color image signal as in the embodiment of FIG.
That is, it avoids repeating the reading of Z (5n) four times.

As is clear from the above description, in the fourth embodiment, since the reading of the full-color image signal for one frame having the same content is repeated twice, the full-color image signal Z (n ) Is about 50 / 3ms (1,000 / 60ms)
The full-color image signal Z (n) for one frame is sequentially output from the memory 28 every time and is converted back to an analog image signal by the D / A converter 38, and then a low pass filter (LPF) 40.
After passing through, the monitor device 1 is amplified by the amplifier (AMP) 42.
8 is output. Thus, in the monitor device 18, the CCD
The image captured by the image sensor 12 is reproduced by an image signal for 60 frames per second and by a progressive scanning method. As in the case of the first, second and third embodiments,
Also in the fourth embodiment, it is preferable that the image reproduction in the PAL system (that is, the interlaced scanning system) can be selectively performed.

Referring to FIG. 18, an image projected on the display screen of the monitor device 18 based on the PAL system and an image projected on the display screen of the monitor device 18 based on the system according to the fourth embodiment of the present invention. An image is shown as an example. In the case of the PAL system, the video is reproduced based on the image signal of 25 frames per second, whereas in the fourth embodiment of the present invention, the video based on the image signal of 60 frames per second is reproduced. Since it is reproduced by the progressive scanning method, it goes without saying that the flicker problem associated with the conventional PAL method is solved as in the second embodiment described above.
According to the fourth embodiment, regarding the smoothness of the movement of the image on the monitor device 18, since the image reproduction for four times based on the full-color image signal for one frame of the same content is avoided, the second embodiment is performed. It will be superior to the form.

Next, a fifth embodiment of the present invention will be described. The block diagram thereof is substantially the same as that of the fourth embodiment shown in FIG. 15, and the fifth embodiment and the fourth embodiment are the same.
The difference from the above embodiment is only the mode of reading a full-color image signal for one frame from the memory 28. In the fifth embodiment, unlike the case of the fourth embodiment, a full-color image signal for one frame of the same content is not read out twice from the memory 28, but for each one frame. Full color image signal is 50 / 3ms (1,000 / 6
It is the same as the fourth embodiment in that it is read from the memory 28 every 0 ms).

As shown in the time chart of FIG. 19, also in the fifth embodiment, as in the case of the fourth embodiment, first, a full-color image signal X (1) for one odd field and one even field are generated. After the full-color image signal Y (1) is written in the odd-numbered field memory areas R1, G1 and B1 and the even-numbered field memory areas R2, G2 and B2, respectively, the full-color image signal X (2) for the next odd-numbered field The full-color image signal Y (2) for one even field is written in the odd-field memory regions R3, G3 and B3 and the even-field memory regions R4, G4 and B4, respectively, and the full-color image signal X for the next odd-numbered field X is written. (3) and the full-color image signal Y (3) for one even field are written in the odd field memory areas R5, G5 and B5 and the even field memory areas R6, G6 and B6, respectively. Such sequential writing is repeated every 120 ms. That is, for the full-color image signal X (3n-2) for one odd field and the full-color image signal Y (3n-2) for one even field,
They are written in the odd field memory areas R1, G1 and B1 and the even field memory areas R2, G2 and B2, respectively, and the full color image signal X (3n
-1) and a full-color image signal Y (3n-
1) and the odd field memory area R
3, G3 and B3 and even field memory areas R4, G4 and B4 are written, and for the full-color image signal X (3n) for one odd field and the full-color image signal Y (3n) for one even field, Odd field memory area R5, G5 and B5 respectively and even field memory area
Written to R6, G6 and B6.

In the fifth embodiment, first, the odd-numbered field memory areas R1, G1 and B1 and the even-numbered field memory areas R2, G2 and B2 respectively have a full-color image signal X (1) and an even-numbered field for one odd-numbered field. The full-color image signal Y (1) for the field is read and these image signals X
The multiplier 52 multiplies (1) and Y (1) by the following coefficients. X (1) × α1 Y (1) × α2 At this time, the coefficients α1 and α2 are both set to 1 (6/6). The result obtained by the multiplier 52 is output to the adder 54, where the following calculation is performed to obtain the full-color image signal Z (1) for one frame. Z (1) = [[X (1) × 6/6 + 0], [Y (1) × 6/6 + 0]] = [X (1), Y (1)]

Next, odd field memory regions R1 and G1
And B1 and the even field memory areas R2, G2 and B2 respectively provide a full color image signal X (1) for one odd field and a full color image signal Y (1) for one even field.
Are read out again, and the image signals X (1) and Y (1) are multiplied by the following coefficients in the multiplier 52. X (1) × α1 Y (1) × α2 At this time, α1 and α2 are both set to 1/6. On the other hand, a full-color image signal Y (1) for one even field is read out again from the even-field memory regions R2, G2, and B2, and a full-color image signal X for one odd-field is read from the odd-field memory regions R3, G3, and B3. (2) is also read out, and the multiplier 52 is added to these image signals Y (1) and X (2).
Is multiplied by the following coefficient. Y (1) × α2 X (2) × α3 At this time, the coefficients α2 and α3 are both set to 5/6. The results obtained by the multiplier 52 are both output to the adder 54, where the following calculation is performed to obtain a full-color image signal Z (2) for one frame. Z (2) = [[X (1) × 1/6 + Y (1) × 1/6], [Y (1) × 5/6 + X (2) × 5/6]]

Next, the even field memory areas R2 and G2
And B2 and the odd field memory areas R3, G3 and B3 respectively, the full color image signal Y (1) for one even field and the full color image signal X (2) for one odd field.
Are read out again, and the image signals Y (1) and X (2) are multiplied by the following coefficients in the multiplier 52. Y (1) × α2 X (2) × α3 At this time, the coefficients α2 and α3 are both set to 2/6. On the other hand, from the odd field memory areas R3, G3 and B3 and the even field memory areas R4, G4 and B4, a full color image signal X (2) for one odd field and a full color image signal Y (2) for one even field, respectively. And are read out,
These image signals X (2) and Y (2) are multiplied by the following coefficient in the multiplier 52. X (2) × α3 Y (2) × α4 At this time, the coefficients α3 and α4 are both set to 4/6. The results obtained by the multiplier 52 are both output to the adder 54, where the following calculation is performed to obtain the full-color image signal Z (3) for one frame. Z (3) = [[Y (1) × 2/6 + X (2) × 2/6], [X (2) × 4/6 + Y (2) × 4/6]]

Continuing, odd field memory areas R3 and G3
And B3 and the even field memory areas R4, G4 and B4 respectively provide a full color image signal X (2) for one odd field and a full color image signal Y (2) for one even field.
Are read out again, and the image signals X (2) and Y (2) are multiplied by the following coefficients in the multiplier 52. X (2) × α3 Y (2) × α4 At this time, the coefficients α3 and α4 are both set to 3/6. On the other hand, from the even field memory areas R4, G4 and B4 and the odd field memory areas R5, G5 and B5, the full color image signal Y (2) for one even field and the full color image signal X (3) for one odd field respectively. And are read out,
These image signals Y (2) and X (3) are multiplied in the multiplier 52 by the following coefficients. Y (2) × α4 X (3) × α5 At this time, the coefficients α4 and α5 are both set to 3/6. The results obtained by the multiplier 52 are both output to the adder 54, and the following calculation is performed there to obtain a full-color image signal Z (4) for one frame. Z (4) = [[X (2) × 3/6 + Y (2) × 3/6], [Y (2) × 3/6 + X (3) × 3/6]]

Next, an even field memory area R4, G4 and B4 and an odd field memory area R5, G5 and B5 are used to output a full color image signal for one even field.
Y (2) and the full-color image signal X (3) for one odd field are read out, and these image signals Y (2) and X (3) are multiplied by the following coefficient in the multiplier 52. Y (2) × α4 X (3) × α5 At this time, the coefficients α4 and α5 are both set to 4/6. On the other hand, from the odd field memory areas R5, G5 and B5 and the even field memory areas R6, G6 and B6, the full color image signal X (3) for one odd field and the full color image signal Y (3) for one even field, respectively. And are read out,
These image signals X (3) and Y (3) are multiplied in the multiplier 52 by the following coefficients. X (3) × α5 Y (3) × α6 At this time, the coefficients α5 and α6 are both set to 2/6. The results obtained by the multiplier 52 are both output to the adder 54, and the following calculation is performed there to obtain a full-color image signal Z (5) for one frame. Z (5) = [[Y (2) × 4/6 + X (3) × 4/6], [X (3) × 2/6 + Y (3) × 2/6]]

Next, odd field memory areas R5 and G5
And B5 and the even field memory areas R6, G6 and B6 respectively provide a full color image signal X (3) for one odd field and a full color image signal Y (3) for one even field.
Are read out, and the image signals X (3) and Y (3) are multiplied by the following coefficients in the multiplier 52. X (3) × α5 Y (3) × α6 At this time, the coefficients α5 and α6 are both set to 5/6. On the other hand, from the even field memory areas R6, G6 and B6 and the odd field memory areas R1, G1 and B1 respectively, a full color image signal Y (3) for one even field and a full color image signal X (4) for one odd field respectively. And are read out,
These image signals Y (3) and X (4) are multiplied by the following coefficients in the multiplier 52. Y (3) × α6 X (4) × α1 At this time, the coefficients α6 and α1 are both set to 1/6. The results obtained by the multiplier 52 are both output to the adder 54, and the following calculation is performed there to obtain a full-color image signal Z (6) for one frame. Z (6) = [[X (3) × 5/6 + Y (3) × 5/6], [Y (3) × 1/6 + X (4) × 1/6]]

When the reading of the full-color image signal Z (6) for one frame is completed, the even field memory areas R6, G6
And B6 and the odd field memory areas R1, G1 and B1 from the full color image signal Y (3) for one even field and the full color image signal X (4) for one odd field, respectively.
And are read out, and these image signals Y (3) and X (4) are multiplied by the following coefficients in the multiplier 52. Y (3) × α6 X (4) × α1 At this time, the coefficients α6 and α1 are both set to 1 (6/6). The result obtained by the multiplier 52 is output to the adder 54, where the following calculation is performed to obtain the full-color image signal Z (7) for one frame. Z (7) = [[Y (3) × 6/6 + 0], [X (4) × 6/6 + 0]] = [Y (3), X (4)]

The full-color image signal Z (7) is created in the same manner as the full-color image signal Z (1), and the full-color image signal Z (n) for one frame after that is obtained by sequentially repeating the above-mentioned read operation. Is obtained by

FIG. 20 shows a table of the interpolation processing of the full-color image signal Z (n) described above. Note that FIG.
The symbol "*" in the table of 0 indicates a product. In short, in the fifth embodiment, 2/6 of each of the continuous six full-frame image signals for one frame are taken out and the full-color image signal for two frames is interpolated, so that 25 frames per second are stored in the memory 28. Minute full-color image signal writing, not only is a full-color image signal for 60 frames per second obtained from it, but it is also necessary to avoid duplication of full-color image signals for one frame of the same content. Full color image signals for 60 frames are individually obtained by interpolation.

Also in the fifth embodiment, each full-frame image signal Z (n) for one frame is sequentially output from the memory 28 at intervals of about 50/3 ms (1,000 / 60 ms), and the full-color image signal for one frame is output. Z (n) is returned to an analog image signal by the D / A converter 38, then passed through a low pass filter (LPF) 40, amplified by an amplifier (AMP) 42, and output to the monitor device 18. Thus, in the monitor device 18, the image captured by the CCD image sensor 12 is reproduced as an image signal for 60 frames per second by the progressive scanning method. As in the case of the first, second, third and fourth embodiments described above, also in the fifth embodiment, it is possible to selectively perform image reproduction in the PAL system (that is, the interlaced scanning system). Preferably.

Referring to FIG. 21, an image projected on the display screen of the monitor device 18 based on the PAL system and an image projected on the display screen of the monitor device 18 based on the system according to the fifth embodiment of the present invention. An image is shown as an example. In the case of the PAL system, the video is reproduced based on the image signal for 25 frames per second, whereas in the fifth embodiment of the present invention, the video based on the image signal for 60 frames per second is reproduced. Since it is reproduced by the progressive scanning method, the flicker problem associated with the conventional PAL method can be solved as in the above-described embodiment. Further, according to the fifth embodiment, regarding the smoothness of the movement of the image on the monitor device 18, since the repetition of the image reproduction based on the full-color image signal for one frame of the same content is completely avoided, it is significantly increased. Can be improved.

Referring to FIG. 22, there is shown a sixth embodiment of an electronic endoscope according to the present invention, in which the same reference numerals are used for the same components as those shown in FIG. . In the sixth embodiment, the rotation frequency of the rotary RGB color filter 20 is switched by a switching signal from the timing generator 26. For example, when the switching signal from the timing generator 26 is low level, the color filter 20 is rotationally driven at a rotation frequency of 30 Hz, and when the switching signal is high level, the color filter 20 is rotationally driven at a rotation frequency of 25 Hz. To be made.

Although omitted in the explanation of the block diagram of FIG.
A clock pulse is output from the timing generator 26 to each of the A / D converter 24 and the D / A converter 38, and the clock pulse converts the analog image signal into a digital image signal and the digital image signal into an analog image signal. Is converted to. Since the frequency of such a clock pulse is determined based on the rotation frequency of the color filter 20, in the sixth embodiment, the A / D converter 24 and the D / A converter are switched according to the switching of the rotation frequency of the color filter 20. The frequency of the clock pulse output to each of 38 is also switched.

As described above, most of the conventional video recording / reproducing devices are designed for the interlaced scanning system, so that the image taken by the electronic endoscope is recorded on the video tape or the like. In some cases, the electronic endoscope is operated in PAL mode. That is, the rotary RGB color filter 20
It is driven at 25 Hz, that is, at 25 revolutions per second. CC at this time
The image signal of each color read from the D image sensor 12 and converted into a digital image signal is written in each field memory area of the memory 28 according to the time chart of FIG. 23, and this writing mode is shown in FIGS. 1 and 2. Same as the case. That is, the red image signal is divided into the odd field data OR (n) and the even field data ER (n), and the field memory areas R1 and R2 respectively.
Alternately, the green image signal is also divided into odd field data OG (n) and even field data EG (n), which are alternately written to the field memory areas G1 and G2, respectively, and the blue image signal is also written. It is divided into odd field data OB (n) and even field data EB (n) and written in the field memory areas B1 and B2, respectively.

Odd field memory areas R1, G1 and B1
To and write to even field memory areas R2, G2 and B2
When writing to each of the odd field memory area and the even field memory area is started, the full-color image signal X (n) for one odd field is written.
= [OR (n), 0G (n), OB (n)] and full-color image signal Y (n) = [ER (n), EG (n), EB (n)] for one even field Read out. The full-color image signal X (n) for one odd field and the full-color image signal Y (n) for one even field sequentially read out from the memory 28 are returned to analog image signals by the D / A converter 38, and then, Low pass filter
After passing through the (LPF) 40, it is amplified by the amplifier (AMP) 42 and output to the monitor device 18. Thus, the monitor device 18
Then, the image captured by the CCD image sensor 12 is reproduced by the PAL system (interlaced scanning system). That is, as is apparent from FIG. 23, the full-color image signal X (n) for one odd field and the full-color image signal Y (n) for one even field, which form the full-color image signal Z (N) for one frame, It is reproduced every 40ms. It should be noted that the time chart shown in FIG. 23 is also for reproducing the video in the PAL system in each of the above-described first, second, third, fourth and fifth embodiments.

In the sixth embodiment shown in FIG. 22,
When the rotary RGB color filter 20 is driven at 30 Hz, that is, 30 rotations per second, the time required for one rotation is 100/3 m.
The illumination time for each color filter is approximately 50 / 9ms. In short, as shown in the time chart of FIG.
From the end face of the tip of the light guide 14, red light R, green light G
And blue light B is approximately 50 / 9ms every 100 / 3ms (1/30 sec)
Are emitted sequentially, and the subject is red light R, green light G
And the blue light B is sequentially formed on the light receiving surface of the CCD image sensor 12. The CCD image sensor 12 converts the subject image of each color formed on the light receiving surface into an analog image signal for one frame, and the analog image signal of each color follows the illumination time of each color (approximately 50/9 ms). It is read from the CCD image sensor 12 for a predetermined time, that is, a shielding time (for example, 50/9 ms). The reading of the analog image signal from the CCD image sensor 12 is performed by a well-known CCD driver circuit (not shown), and the analog image signal of each color is subjected to predetermined image processing such as gamma correction in the CCD process circuit 22 and then analog / image It is converted into a digital image signal by the digital (A / D) converter 24. In addition,
As in the case described above, since the spectral sensitivity characteristic of the CCD image sensor 12 and the output power of each color from the color filter 20 are different, the illumination time by the red light R 1, the green light G, and the blue light B is different. Although slightly different, the reading of each color image signal from the CCD image sensor 12 is performed within the same shielding time.

The digital image signals of the respective colors are written in the respective memory areas of the memory 28 by the timing generator 26, and the writing mode is substantially the same as in the case of FIG. 23 except for the difference in the writing frequency. That is,
As shown in the time chart of FIG. 24, the red image signal has odd field data OR (n) and even field data ER.
field memory area R1
And R2 are written alternately, and the green image signal is also odd field data OG (n) and even field data EG (n).
And are alternately written into the field memory areas G1 and G2, respectively, and the blue image signal is also odd field data OB (n) and even field data EB (n).
Are divided into the field memory area B1 and
It is written in B2, and the written contents are updated every 100 / 3ms.

Odd field memory areas R1, G1 and B1
To and write to even field memory areas R2, G2 and B2
When writing to each of the odd field memory area and the even field memory area is started, the full-color image signal X (n) for one odd field is written.
= [OR (n), 0G (n), OB (n)] and full-color image signal Y (n) = [ER (n), EG (n), EB (n)] for one even field The reading and reading of the full-color image signal for each one field having the same content are repeated twice. The full-color image signal X (n) for one odd field and the full-color image signal Y (n) for one even field, which are sequentially read from the memory 28, are alternately arranged for each horizontal scanning line in the D / A converter 38.
D / A converted to analog image signal by, then low-pass filter (LPF) 40 and then amplifier (AMP) 4
It is amplified by 2 and output to the monitor device 18. Thus, in the monitor device 18, the image captured by the CCD image sensor 12 is reproduced by the progressive scanning method. In this case, one frame image of the same content is repeatedly reproduced twice every about 100/3 ms, so that this image reproduction is similar to the image reproduction according to the fourth embodiment (FIG. 18).

The time chart shown in FIG. 25 is when the rotary RGB color filter 20 is rotated at 60 Hz in the electronic endoscope shown in FIG. 22, and in this modified embodiment,
The writing speed of the image signal to each field memory area of the memory 28 and the reading speed of the image signal from the writing speed are shown in FIG.
It is doubled compared to the case of the time chart shown in Fig. 4, and one frame image is updated every 50 / 3ms. Thus,
The reproduced image is a reproduced image according to the fifth embodiment (see FIG. 2).
It will be similar to 1).

Referring to FIG. 26, there is shown a seventh embodiment of an electronic endoscope according to the present invention, in which the same reference numerals are used for the same components as those shown in FIG. . In the seventh embodiment, the rotary RGB color filter 20 is driven to rotate at a rotation frequency of 25 Hz or higher. For example, if the color filter 20
When it is driven to rotate at a rotation frequency of 30Hz,
In a manner similar to that described with reference to the time chart of FIG.
Can be done in. When the color filter 20 is rotationally driven at a rotational frequency of 60 Hz, image reproduction is performed by the monitor device 18 according to the progressive scanning method in a manner similar to that described with reference to the time chart of FIG.

In the seventh embodiment shown in FIG. 26, the full color image signal for 25 frames per second is read from the writing of the full color image signal for 30 frames or 60 frames per second to the memory 28. Then, the image is reproduced by the PAL method (interlaced scanning method).
In the seventh embodiment, the monitor device 18 is capable of reproducing an image only by the progressive scanning method.
The image reproduction in the L system is performed by the monitor device 18 'for the interlace system.

Next, in the seventh embodiment, a case where image reproduction is performed by the PAL system when the rotary RGB color filter 20 is driven to rotate at a rotation frequency of 30 Hz will be described below.

Regarding the mode of writing the image signals of the respective colors read from the CCD image sensor 12 and converted into the processed digital image signals into the memory 28, refer to FIG. 11 except that the frequency of the clock pulse at the time of writing is different. This is substantially the same as the case described above. More specifically, as shown in the time chart of FIG. 27, first, the full-color image signal X (1) for one odd field and the full-color image signal Y (1) for one even field are respectively odd field memory regions R1 and G1. And B1 and even field memory area R2, G2
After being written in B2 and B2, the next full-color image signal X (2) for one odd field and the full-color image signal Y (2) for one even field are stored in the odd field memory areas R3, G3 and B3 and the even field, respectively. The data is written in the memory areas R4, G4 and B4, and such alternate writing is repeated every 100/3 ms. That is, the full-color image signal X (2n-1) for one odd field and the full-color image signal Y (2n-1) for one even field are odd field memory areas R1, G1 and B1 and even field memory area R2, respectively. The full-color image signal X (2n) for one odd field and the full-color image signal Y (2n) for one even field are written to G2 and B2, respectively. Written in regions R4, G4 and B4.

The odd-field memories R1, G1 and B1 and the even-field memory areas R2, G2 and B2 are supplied with the full-color image signal X (1) for one odd field and the full-color image signal Y (1) for one even field. When writing is completed,
First, the full-color image signal X (1) for one odd field is read from the odd field memories R1, G1 and B1,
Next, the even color field full-color image signal Y (1) is read from the even-field memory areas R2, G2, and B2, and the read time of both full-color image signals X (1) and Y (1) is set to 40 ms. It Then, during the next 40 ms, the full-color image signal X (2) for one odd field and one even field from each of the odd field memories R3, G3 and B3 and the even field memory areas R4, G4 and B4. The full-color image signal Y (2) is sequentially read. That is, from the odd field memories R1, G1 and B1 and the even field memory areas R2, G2 and B2, the full color image signal X (2n-1) for one odd field and the full color image signal Y (2n for one even field -1) and the odd field memories R3, G3 and B3 and the even field memory areas R4, G4 and B4 are read from the full color image signal X (2n) of one odd field and one even field. The full-color image signal Y (2n) is read out.

However, the odd field memory R3,
G3 and B3 and even field memory area R4, G4 and B4
The full-color image signal X (2n = 6m) for one odd field and the full-color image signal Y (2n = 6m) for one even field, which are respectively written in and, are not read out and are thinned out. That is, as shown in FIG. 27, full-color image signals X (6) and Y (6) and full-color image signals X (12) and
For Y (12), memory 28 (ie odd field memories R3, G3 and B3 and even field memory area R4,
Read from G4 and B4). Thus, the memory 28
From a full-color image signal equivalent to 25 frames per second
X (n) and Y (n) are read out, and these full-color image signals X (n) and Y (n) are digital / analog (D / A) converter 3
8'returns to an analog image signal, then passes through a low pass filter (LPF) 40 ', is amplified by an amplifier (AMP) 42', and is output to a monitor device 18 ', where PAL image reproduction is performed.

[0087]

As is apparent from the above description, according to the present invention, since it is possible to reproduce an image by a progressive scanning method with an electronic endoscope, the flicker problem associated with the image reproduction by the conventional PAL method is reduced. Alternatively, it can be resolved. Further, when the electronic endoscope according to the present invention is configured to be capable of reproducing images in the PAL system, it is possible to use peripheral devices such as conventional video recording / reproducing devices and monitor devices. Benefits are obtained. Further, as a notable advantage of the present invention, the conventional PAL type electronic endoscope is not entirely changed in design, but is only partially changed, that is, by changing the reading mode from the memory. Since the image can be reproduced by the progressive scanning method, it is possible to change the PAL method of the electronic endoscope from the progressive scanning method at a low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an electronic endoscope according to the present invention.

FIG. 2 is a time chart for explaining writing of a full-color image signal to a memory and reading of a full-color image signal from the memory in the first embodiment shown in FIG.

FIG. 3 is a time chart for explaining reading of an image signal for one horizontal scanning from the memory in the first embodiment shown in FIG.

FIG. 4 is a time chart for explaining writing of full-color image signals for odd and even fields to the memory and reading of a full-color image signal for one frame from the memory in the first embodiment shown in FIG. Is.

5 is a block diagram showing a part of the configuration of the timing generator in the first embodiment shown in FIG. 1. FIG.

FIG. 6 is a time chart for explaining the operation of the block diagram of FIG.

FIG. 7 is another time chart for explaining the operation of the block diagram of FIG.

FIG. 8 is a block diagram showing a part of the configuration of the timing generator in the first embodiment shown in FIG. 1, showing an example different from the block diagram of FIG.

9 is a reproduction image according to the first embodiment shown in FIG.
It is a schematic diagram which shows the relationship with the reproduced image by PAL system.

FIG. 10 is a block diagram showing a second embodiment of an electronic endoscope according to the present invention.

11 is a time chart for explaining writing of full-color image signals for odd and even fields to a memory and reading of a full-color image signal for one frame from the memory in the second embodiment shown in FIG. Is.

12 is a schematic diagram showing a relationship between a reproduced image according to the second embodiment shown in FIG. 10 and a reproduced image according to the PAL method.

FIG. 13 is a view for explaining writing of full-color image signals for odd and even fields to a memory and reading of a full-color image signal for one frame from the memory in the third embodiment of the electronic endoscope according to the present invention. Is a time chart of.

FIG. 14 is a schematic diagram showing a relationship between a reproduced image according to the third embodiment of the electronic endoscope according to the present invention and a reproduced image according to the PAL method.

FIG. 15 is a block diagram showing a fourth embodiment of the electronic endoscope according to the present invention.

16 is a time chart for explaining writing of full-color image signals for odd and even fields to the memory and reading of a full-color image signal for one frame from the memory in the fourth embodiment shown in FIG. Is.

FIG. 17 is a table showing the contents of the interpolation processing performed after reading the full-color image signal from the memory in the fourth embodiment shown in FIG.

FIG. 18 is a schematic diagram showing a relationship between a reproduced image according to the fourth embodiment shown in FIG. 15 and a reproduced image according to the PAL method.

FIG. 19 is a view for explaining writing of full-color image signals for odd and even fields to a memory and reading of full-color image signals for one frame from the memory in the fifth embodiment of the electronic endoscope according to the present invention. Is a time chart of.

FIG. 20 is a table showing the contents of the interpolation processing performed after reading the full-color image signal from the memory in the fifth embodiment of the electronic endoscope according to the present invention.

FIG. 21 is a schematic diagram showing a relationship between a reproduced image according to the fifth embodiment of the electronic endoscope according to the present invention and a reproduced image according to the PAL method.

FIG. 22 is a block diagram showing a sixth embodiment of the electronic endoscope according to the present invention.

FIG. 23 is a view for explaining writing of full-color image signals for odd and even fields to the memory and reading of a full-color image signal for one frame from the PAL system in the sixth embodiment shown in FIG. 22; Is a time chart of.

24 illustrates writing of full-color image signals for odd and even fields to the memory and reading of a full-color image signal for one frame from the memory in the sixth embodiment illustrated in FIG. 22 by a sequential scanning method. It is a time chart for.

FIG. 25 shows the writing of full-color image signals for odd and even fields to the memory in the sixth embodiment shown in FIG. It is a time chart for explaining.

FIG. 26 is a block diagram showing a seventh embodiment of the electronic endoscope according to the present invention.

FIG. 27 is a view for explaining writing of full-color image signals for odd and even fields to a memory and reading of a full-color image signal for one frame from the memory in the seventh embodiment shown in FIG. 26 by the PAL method. Is a time chart of.

[Explanation of symbols]

 10 scope 12 CCD image sensor 14 light guide 16 light source 18 color monitor device 20 rotary RGB color filter 22 CCD process circuit 24 analog / digital (A / D) converter 26 timing generator 28 memory 30 horizontal counter 32 vertical counter 34/36 Decoder 38 Digital / Analog (D / A) converter 40 Low-pass filter (LPF) 42 Amplifier (AMP)

Claims (18)

[Claims] 1. A solid-state image pickup device and an image signal for one frame read from the solid-state image pickup device are divided into an odd field image signal and an even field image signal at a first time interval and are temporarily stored. Memory means for reading the odd field image signal and the even field image signal from the memory means twice at a second time interval to create an image signal for two frames for the progressive scanning method. And an image signal generating means of the electronic endoscope. 2. The electronic endoscope according to claim 1, wherein
The memory means further comprises second image signal generating means for alternately reading the odd field image signal and the even field image signal at the first time interval to generate an image signal for one frame for the interlaced scanning method. An electronic endoscope that does. 3. The electronic endoscope according to claim 1, wherein the first time interval and the second time interval are equal to each other. 4. The electronic endoscope according to claim 1, wherein the second time interval is shorter than the first time interval. 5. The electronic endoscope according to any one of claims 1 to 4, wherein the first image signal creating means has the same contents as image signals for two frames for a progressive scanning system. An electronic endoscope, which is characterized by: 6. The electronic endoscope according to any one of claims 1 to 4, wherein the first image signal creating means differs as an image signal for two frames for a progressive scanning method by interpolation processing. An electronic endoscope characterized in that it creates a thing with different contents. 7. The electronic endoscope according to claim 1, wherein the image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method. An electronic endoscope characterized by being present. 8. A solid-state image pickup device and an image signal for one frame read from the solid-state image pickup device are divided into an odd field image signal and an even field image signal at a first time interval and are temporarily stored. And the odd-numbered field image signal and the even-numbered field image signal are read twice from the memory means at a second time interval shorter than the first time interval, and two frames for a progressive scanning method are read. An electronic endoscope comprising: a first image signal creating means for creating an image signal. 9. The electronic endoscope according to claim 8, wherein:
The memory means further comprises second image signal generating means for alternately reading the odd field image signal and the even field image signal at the first time interval to generate an image signal for one frame for the interlaced scanning method. An electronic endoscope that does. 10. The electronic endoscope according to claim 8 or 9, wherein the first image signal creating means creates the same contents as the image signals for two frames for the progressive scanning method. And an electronic endoscope. 11. The electronic endoscope according to claim 10, wherein an odd field image signal and an even field image from the memory means are output according to a difference between the first time interval and the second time interval. The first image signal creating means creates an image signal for at least one frame of the same content in addition to the image signal for two frames for the sequential scanning method every predetermined number of times of reading with the signal. An electronic endoscope characterized by: 12. The electronic endoscope according to claim 8, wherein the first image signal creating means creates two frames of image signals for a progressive scanning method with different contents by interpolation processing. An electronic endoscope characterized by: 13. The electronic endoscope according to claim 12, wherein an odd field image signal and an even field image from the memory means are output according to a difference between the first time interval and the second time interval. The first image signal creating means creates an image signal for at least one frame by interpolation processing in addition to the image signal for two frames for the sequential scanning method every predetermined number of times of reading with the signal. An electronic endoscope characterized by: 14. The electronic endoscope according to claim 8, wherein the image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method. An electronic endoscope characterized by being present. 15. A solid-state image pickup device and an image signal for one frame read from the solid-state image pickup device are odd-numbered at any one time interval selected from a first time interval and a second time interval. Memory means for temporarily storing the field image signal and the even field image signal separately, and an odd field image signal and an even field image signal from the memory means when the first time interval is selected. When the first image signal producing means for producing the image signal for one frame for the interlaced scanning method by alternately reading out once at the first time interval and the second time interval are selected In addition, the odd-field image signal and the even-field image signal are read twice from the memory means at the second time interval and the image signal for two frames for the progressive scanning method is read. An electronic endoscope comprising: a second image signal creating means for creating a signal. 16. The electronic endoscope according to claim 15, wherein the image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method. Endoscope. 17. A solid-state image pickup device and an image signal for one frame read from the solid-state image pickup device are divided into an odd field image signal and an even field image signal at a first time interval and temporarily stored. Memory means for reading the odd field image signal and the even field image signal twice from the memory means at the first time interval to create an image signal for two frames for the progressive scanning method. 1 image signal creating means and the odd field image signal and the even field image signal are alternately read out from the memory means at a second time interval longer than the first time interval to obtain one frame for interlaced scanning. An electronic endoscope comprising: a second image signal creating means for creating the image signal of FIG. 18. The electronic endoscope according to claim 17, wherein the image signal for one frame read from the solid-state imaging device is a color image signal obtained by a frame sequential method. Endoscope.