JPH04104687A - Image freezing device - Google Patents

Abstract

PURPOSE:To obtain a sharp image by detecting the motion of a subject and detecting the photographic timing of a frozen image automatically. CONSTITUTION:Two semifield image signals are read out of a field memory 12, stored with respective semifield image signals obtained by a solid image pickup element 5, alternately, line by line, to generate simultaneous type composite field image data, and a composite color image signal is generated with the composite field image data of respective colors. The output level difference between one line of the composite field image-data and the following line is detected by a detecting means 22 to detect whether or not the subject is in motion and when the motion detecting means 22 detects no motion of the subject, freezing operation is performed by a switch means 20. Consequently, the frozen image is obtained in the least motion state and the frozen image has no color slurring and is sharp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention is applicable to an image carrying means attached to an electronic endoscope, etc.
The solid-state image sensor is driven in a frame-sequential manner to obtain image signals of each color of R (red), G (green), and B (blue), and these image signals of each color are superimposed and displayed in color on a monitor screen, etc. The present invention relates to an image freezing device that also enables the acquisition of still images.

[Prior Art 1] Since electronic endoscopes are inserted into narrow areas such as body cavities, the tip of the insertion portion must be as thin as possible.

Therefore, C as an imaging means built into the tip of the insertion section.
A solid-state image sensor such as a CD needs to be small and compact, and for this reason, it is common to use a single solid-state image sensor. In order to improve the resolution of images obtained by this single-plate solid-state image sensor, the solid-state image sensor is driven in a frame sequential manner to
, B are acquired, and these video signals of each color are superimposed and displayed as a color video on a display device.

When observing the inside of the body using an electronic endoscope, in addition to observing the image as a moving image, it is often displayed as a still image on a display device, or this still image is recorded using a camera. You may be required to do something. In particular, when recording observation records, they are often recorded as still images rather than moving images.

In response to such demands, imaging systems for electronic endoscopes are now capable of displaying not only normal moving images but also still images, that is, frozen images.

[Problems to be Solved by the Invention] By the way, when driving a solid-state image sensor in a frame-sequential manner, image signals 1 of each color of R, G, and B are captured in chronological order to form the entire image. Since there is a time lag between the image signals of each color, if either or both of the subject side and the image carrier side move during shooting, when these image signals of each color are superimposed, each image signal It becomes impossible to maintain alignment between the two. Therefore, regardless of when this video is displayed in a moving image state, when displaying it as a frozen image, there is a drawback that color shift occurs in the image, the resolution decreases, and the image becomes extremely unsightly.

Therefore, in order to obtain clear frozen images, the operator of the electronic endoscope repeatedly operates the operating means such as the freeze shooting button, and selects the one with the least movement (,
Clear images are selected and recorded, which makes the operation of taking frozen images extremely troublesome.

The present invention has been made in view of the above-mentioned points, and its purpose is to automatically detect the photographing timing of a frozen image by detecting the movement of a subject using a simple configuration. An object of the present invention is to provide an image freezing device capable of acquiring clear images.

[Means for Solving the Problems 1] In order to achieve the above-mentioned object, the present invention is provided at the distal end of the insertion section of an electronic endoscope, and is provided at the distal end of the insertion section of an electronic endoscope, and is configured to record image data of each color of R, G, and B with a time difference. It has a solid-state image pickup device that acquires two semi-field image signals, and a field memory that stores each semi-field image signal acquired by the solid-state image pickup device, and stores two semi-field image signals from the field memory. a processor that generates simultaneous composite field image data by alternately reading each line and forming a composite color video signal from the composite field image data of each color; a motion detecting means for detecting the presence or absence of movement of the subject by comparing the output level difference between the two; and a switch means for causing a freeze operation when the motion detecting means detects that there is no movement of the subject. This is its characteristic.

[Function l] In recent years, CCDs with extremely high sensitivity have been developed and used as solid-state imaging devices, and with such high-sensitivity CCDs, the sampling time of the image signal of one field is shorter than the normal sampling time. During this period, it is possible to accumulate charge and read it out multiple times. Therefore, by acquiring image data for two semi-fields for each color image data of R, G, and B, and combining these two semi-field image signals line by line, one composite field image is created. data can be obtained. With this configuration, the sensitivity and resolution of the solid-state image sensor can be significantly improved,
Moreover, the device can be made smaller, which is extremely advantageous when used as an endoscope.

When photographing a subject using such a high-sensitivity CCD, the two semi-field image signals described above are acquired with a predetermined time difference. Therefore, the motion of the subject can be detected by comparing the signal levels of each scanning line in these two semi-field image signals and taking the difference.

Therefore, in the present invention, R, G
, B, and perform processing to generate a composite field image signal from them.The composite field image signal is taken into the motion detection means and the signal level of that 1 line is calculated. , and the signal level of the next line. Since the two signals compared here are obtained with a time difference, it is detected based on the comparison result whether or not the subject is moving during this time difference. Here, this comparison is
For example, a comparison circuit may be connected to the output side of the field memory, and an image signal may be input directly to one input terminal of the comparison circuit without delay, and the other input terminal may be connected to the IH delay circuit. This is achieved by inputting the signals with a delay of l lines and comparing the output levels of these two signals. The presence or absence of movement can be detected based on whether this level difference exceeds or falls below a predetermined reference value.

Here, the condition of the subject given as the reference value only needs to be such that there is virtually no color shift and a clear still image can be obtained, and the subject does not necessarily have to be stationary. It is not intended to be.

Therefore, after the freeze operation is performed by the freeze operation means, when the level difference signal from the above-mentioned comparison circuit becomes less than the above-mentioned reference value, the switch means is actuated to prohibit updating of data in the memory. do.

This makes it possible to obtain a clear frozen image without one color shift.

Incidentally, in the outline of a subject, a difference may occur in the signal output level in the vertical direction even though there is no movement. In order to prevent such contours from being erroneously determined to be movement of the subject, a contour pattern change detection means is provided, and this contour pattern change detection means detects the output level of the first line and the output level of the second line. The output signal of the motion detecting means is removed by comparing the output level of the signal and calculating the difference, that is, the difference between lines within the same semi-field. As a result, non-motion signal components included in the motion detection signal of the motion detection means can be eliminated, further improving motion detection accuracy.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 1 shows the overall configuration of an electronic endoscope imaging device. In the figure, 1 indicates a light source lamp, and 2 indicates a light guide.
A rotary color filter 3 is interposed in the illumination optical path leading to point a. This color filter 3 has an R filter region that transmits light in the R (red) wavelength region, a G filter region that transmits light in the G (green) wavelength region, and a filter region that transmits light in the B (blue) wavelength region. A pair of B filter regions are formed with a light shielding region in between. Therefore, by rotating this color filter 3, illumination with wavelength light of each color of R, G, and B is performed repeatedly twice in sequence. The R2O and B illumination lights are sequentially transmitted by the light guide 2 and irradiated from the output end 2b toward the subject via the illumination lens 4.

Next, 5 indicates a CCD, and the image of the subject that is sequentially illuminated with R, G, and B as described above is formed on the imaging plane of the CCD 5 and photoelectrically converted, and a drive pulse from the CCD drive circuit 6 is generated. By applying these to the CCD 5, the image signals are sequentially read out. The image signals of each color of R, G, and B are transmitted to the processor 7, which performs predetermined signal processing and converts them into simultaneous signals, so that the subject image is displayed in color on the screen of the display device. It is now displayed.

Here, the CCD 5 constituting the imaging means is a normal CCD.
The number of pixels in the light-receiving area and accumulation area is approximately twice that of the conventional endoscopes, and the number of pixels in the vertical direction is approximately twice that of that used in conventional endoscopes. It is half. However, in order to maintain good resolution in the horizontal direction, the number of pixels in the horizontal direction is not much different from that of a conventional CCD.

Then, in each of the R, G, and B illumination periods, the CCD
The video processor 4
1 to perform predetermined signal processing. Here, this signal charge is read out by 2-pixel mixed readout in which two lines in the vertical scanning lines are added and read out.

That is, as shown in FIG. 2, in each wavelength light, the first
During the shading period after illumination by the filter area, as shown on the left side of the figure, two lines, one line and the previous line, are added and read out.
- Obtain a semi-field signal. In addition, in the light-blocking period after the illumination by the second filter region, a combination different from that described above, that is, as shown on the right, by adding and reading one line and the next line, Obtain other semi-field signals. And R
By illuminating the filter region, G filter region, and B filter region in this order, the CCD 5 sequentially outputs two semi-field signals for each color. In the following description, for convenience, one semi-field will be referred to as an odd field, and the other semi-field will be referred to as an even field.

Next, the processor 7 has a first signal processing means PjlO that processes the output signal from the CCD 5, and the output signal of the first signal processing means IO is converted into a digital signal by the A/D converter 11. The data will then be stored in the field memory 12.

Here, as mentioned above, the illumination for the subject is R, G.
Since the irradiation is performed twice for each color wavelength of , B, the irradiation timing is as shown in FIG. 3(a).

Therefore, when the CCD 5 is driven, two types of image data, odd field data (0) and even field data (E), are generated for each color of RlG and B, as shown in FIG. 3(b). Things are obtained sequentially and in chronological order.

Then, this data is stored in the field memory 12.
, G, and B memory areas 12R and 12G.

12B, but this memory area 12R112
G and 12B are odd memory areas 12R0゜12, respectively.
G,, 12Bo and even memory area 12R,, 12G,
, 12Ge. However, in reality, the odd memory area and even memory area are processed by processing addresses in the memory area, and the memory area is not divided into two. That is, when writing to the field memory 12, odd-numbered fields and even-numbered fields may be written alternately on the address line.

The data for each color written in the field memory 12 in this way is converted into an analog signal by the D/A converters 13R, I3G, and 13B, and then subjected to signal processing by the second signal processing means 14, and then sent to the color encoder 1.
5. Here, this field memory 12
When reading signals from the memory area, the signals are read alternately from the odd memory area and the even memory area line by line.
As shown in FIG. 3(C), data for each color is simultaneously read out to the color encoder 15 via D/A converters 13R, 13G, and 13B, and mixed by the color encoder 15. , a composite video signal is output.

Here, FIG. 4 shows another example of irradiation timing. In the case shown in the same figure, the rotation speed of the color filter is increased twice as compared to that in Fig. 3. For example, R, G, H
Assuming that the synchronization for one rotation is set to 1720 seconds, in the case of FIG. 4, the period of one rotation of R, G, and B is set to 1/40 seconds. The figure (a) shows the irradiation timing of this illumination light, and the output signal of the CCD 5 is shown in the figure (a).
As shown in b), as image data of each color of R, G, and B, even field data of the same color is obtained in chronological order 1/40 seconds after the odd field data. This data is stored in the field memory 12 as R, G,
For example, odd field data of R is first written to the R area memory 12R, and when even field data is written 1740 seconds later, data is written to the R area memory 12R, 12G, and 12B. 1 from odd memory area and even memory area
The lines are read out alternately and R, G, and B are output simultaneously. Furthermore, in the same figure (C), data of each color is simultaneously read out via D/A converters 13R, 113G, and 13B, respectively. Then, following the same procedure, the image data of each color of G and B is stored in memory areas 12G and 12B.
is input to and read out.

A memory drive circuit 16 is provided in order to read data in the field memory 12 described above and drive control of the readout, and the memory drive circuit 1
6 detects when each of the R, G, and B filter regions of the color filter 3 faces the illumination optical path and selects the R, G, and B filter regions.
, H, and a synchronizing signal generator 18. Furthermore, data writing and reading into and from the field memory 12 are controlled based on the signals from the enable signal control circuit 17 and the synchronizing signal generator 18. Further, the synchronization signal generated from the synchronization signal generator 18 is transmitted to the CCD drive circuit 6 via the timing pulse generator 19.
It is now transmitted to

Here, in addition to displaying the image of the subject in the form of a moving image, the display device can also display it as a frozen image in a still state by switching the display mode. For this purpose, a freeze operation means 8 is provided at an appropriate position such as the main body operation section of the endoscope, and an analog switch 20 as a switch means is connected to this freeze operation means 8. Therefore, when the freeze operation means 8 is operated, the analog switch 2
0 is activated to cut the signal from the freeze operation means 8, the enable signal control circuit 17 is activated, and the data rewriting command signal is no longer input to the field memory 12, and the data currently stored in the memory is The contents will be retained.

Also, at the same time, the shutter control means 21 operates,
The camera shutter will be activated.

By the way, since there is a time difference between the acquisition of the R, G, and B color image signals output from the CCD 5,
If there is a relative movement between the D5 and the distal end of the insertion section of the endoscope equipped with it, a shift will occur between each color image. For this purpose, a motion detection means 22 is provided for detecting the motion of the subject, and even if the freeze operation means 8 is operated, if the motion detection means 22 determines that there is movement of the subject, the analog switch 20 is activated. Make it work and don't freeze. Only when the motion detection means 22 determines that there is no movement of the subject, the freeze operation means 8 is connected to the enable signal control circuit 17 via the analog switch 20.

Therefore, the configuration of the motion detection means 22 will be explained below.

As this motion detection means 22, the second signal processing means 1
4 (or between the second signal processing means 14 and the color encoder 15), the signal output level of the - line (OH) and the next signal delayed by IH through the IH delay circuit 23. It is comprised of a comparator 24 that detects the difference with the signal output level of the line (IH), that is, a level difference between 0H and 1H, and a waveform processing circuit 25 that processes the output signal from the comparator 24 into a waveform. Here, the image signal output from the field memory 12 is a composite field image signal in which two semi-field signals of odd number and even number are folded in alternately line by line. Therefore, even if the OH signal is an odd field signal, For example, the IH times signal is always an even field, and if the OH signal is an even field signal, the IH times signal is always an odd field. Since there is a time difference between the odd field signal and the even field signal, executing OH-LH means detecting an image shift based on the time difference.

A waveform processing circuit 25 that processes the waveform of the output signal from the comparator 24 inverts the negative (-) signal of the level difference signal. Although the sensitivity regarding the level difference is improved by passing the signal through the waveform processing circuit 25, it is also possible to extract only the positive component or the negative component of the level difference signal, and,
The output signal from this waveform processing circuit 25 is integrated by an integrating circuit 26, and only when this level difference is below a predetermined reference value, the signal from the freeze operation means 8 is enabled by the operation of the analog switch 20. The configuration is such that the rewriting of the field memory 12 is prohibited and the image is frozen, and the shutter control means 21 is operated to turn on the shutter of the camera.

This embodiment is constructed as described above, and its operation will be explained next.

When observing and diagnosing the inside of the body using an electronic endoscope, its insertion part is inserted into the stomach, duodenum, etc. through the oral cavity, nasal cavity, etc. At this time, the light source lamp 1 is turned on and the color filter 3 is rotated. This allows imaging of the inside of the body cavity, and this imaging is usually displayed on a display screen in the form of a moving image.

By the way, when inspecting a diseased part or the like more precisely or when storing it as a record, it is displayed as a still frozen image on a display screen. in this case,
Operate the freeze operation means 8. However, when this freeze operation means 8 is operated, C
If there is a relative movement between the CD 5 and the subject, there will be a shift between the image data output to each field memory 12R, 12G, and 12B. Misalignment may occur and the resolution may be poor, making it impossible to make accurate observations.

First, from the output side of the field memory 12, out of the composite field image data, for example, a G image signal is taken in,
The OH data shown in FIG. 5(a) and the IH delay circuit 2
The comparator 24 manually calculates OH-IH using the IH data shown in FIG. This allows odd numbers with a time lag,
The signal level difference between the upper and lower lines in each even-numbered field is sequentially calculated for each line. by this,
The comparator 24 outputs a level difference signal shown in FIG. Furthermore, this signal is sent to the waveform processing circuit 25 where the negative component of the signal is inverted as shown in FIG. . When the integrated value by the integrating circuit 26 exceeds a predetermined reference value set in advance, it is determined that the subject is moving on the relevant screen, the analog switch 20 is activated, and the freeze operation means 8 is not connected to the enable signal control circuit 17, image data on the next screen is acquired,
The same process as described above is performed, and this 0H-IH comparison is performed until the integrated output value from the integrating circuit 26 falls below the reference value. When the comparison value becomes smaller than the set value, the analog switch 20 is turned on. The freeze control means 8 is activated via the enable signal control circuit 17, and a command to prohibit the output of the enable signal is sent to prevent the memory contents of the field memory 12 from being updated, and also to prevent the shutter from being updated. A signal is input to the control means 21, and the shutter of the camera is turned on.

In this way, when the freeze operation means 8 is operated,
The movement detection means 22 detects whether or not the subject is moving, and only when it is determined that there is no movement, the image is frozen via the analog switch 20, so when capturing a frozen image, A clear frozen image without color shift can be reliably obtained with a single operation.

Although the configuration is shown in which motion detection is performed using a G image signal, the above-described motion detection may be performed using any of R, G, or H image signals.

Next, FIGS. 6 and 7 show a second embodiment of the present invention. In this embodiment, the same or equivalent components as in the first embodiment described above are given the same reference numerals. Therefore, the explanation thereof will be omitted.

Therefore, in the first embodiment described above, the comparator 24
The comparison results may include not only changes in the subject's movement, but also changes in the outline of the subject's pattern. Therefore, from the output signal from the comparator 24, a component that is not a motion of the subject, that is, a component based on a change in the contour pattern is removed to detect the motion of the subject more accurately.

In order to detect the contour pattern change part of such a subject,
A contour pattern change portion detection means 30 is provided. This contour pattern change portion detection means 30 has a second comparator 31 and a second waveform processing circuit 32, and receives the comparator 30 of the cylinder 2 directly from the field memory 12, and also
A signal delayed by 2H is taken in through the delay circuit 33, and 0H-2H calculation is performed.

Here, the signal at OH and the signal at 2H are from the same semi-field, and the signal is at a position shifted by one line in the vertical direction of the semi-field, so the difference between the two signals is due to the difference in the subject. This is a portion of the contour pattern that changes in the vertical direction. Therefore, as shown in FIG. 6(b), for the OH-IH level difference signal from the comparator 24 shown in FIG. 6(a), the second comparator 31
(When a signal of a predetermined level is output based on the calculation result of IH-2H, it is input to the gate circuit 34 to prevent the signal from the comparator 24 from being input to the integration circuit 26. , of the OH-IH level difference signal in the comparator 24, it becomes possible to remove the changing portion of the contour pattern, which is a non-motion component of the subject.
The movement of the subject can be detected more accurately.

Furthermore, FIG. 8 shows a third embodiment of the present invention. In this embodiment, the output signal from the field memory 12 is kept as a digital signal, and is
It is output as an LH delay signal via the H delay circuits 40R, 40G, and 40B, and the 6 image data is output as an O delay signal.
It is configured to output H data as well. And R,G
, B's LH data and G's OH data are each D/A.
Converter 41R.

41Go, 41G, , 41B convert it into an analog signal, and then the D/A converters 41G, , 41
The output signal from G is taken into the comparator 42, and the comparator 42 calculates OH-LH. Thereafter, this calculation result is input to the waveform processing circuit 25 as a motion detection signal, and the same processing as in the first embodiment described above is performed.

Here, the aforementioned LH delay circuits 40R and 40G.

In 40B, delay processing is performed in the digital signal state, so the signal is stabilized and the circuit configuration is significantly simplified. For configurations other than these,
Since this embodiment is substantially the same as the first embodiment, the same or equivalent components are given the same reference numerals in the figures.

Furthermore, as shown in FIG. 9, the digital output signal from the field memory 12 is read out in the OH state, and is also read out with a delay of IH via the IH delay circuits 50R, 750G and 50B, respectively, and the D/
A converters 51Ro, 51R,, 51G,.

51G, , 51B, , 51B, and then the output signals from the D/A converters 51R, , SIR, are sent to the comparator circuit 52R and the D/A converter 5
The output signals of 1G, , 51G+ are input to the comparison circuit 52G, and the output signals of the D/A converters 51B, , 51B are input to the comparison circuit 52B, and 0H-LH are input for each image data of R, G, and B, respectively. The waveform processing circuits 53R, 53G, and 53B perform waveform processing, obtain motion detection signals for image data of each color, add these in an adder 55, and integrate them in an integration circuit 54. You can do it like this. With this configuration, the sensitivity during motion detection can be improved.

Also, these third. In the fourth embodiment, as in the second embodiment, the calculation of OH−2H is performed, and OH
- It is possible to remove the changing portion of the contour pattern, which is a non-motion component of the subject, from the IH level difference signal. By performing this 2H delay operation in the digital signal state, the circuit configuration is simple and the signal can be stabilized.

[Advantageous Effects of the Invention 1] As explained above, the present invention acquires two semi-field image signals with a time difference for each color of image data as R, G, and B color image data using a solid-state image sensor. two semi-field image signals are read out alternately line by line from the field memory to generate composite field image data, and this composite field image data 1
By comparing the output level difference between one line and the next line, the movement of the subject is detected and the timing to prohibit rewriting of the field memory is set. By simply performing the freeze operation twice, it is now possible to reliably and accurately detect the movement of the subject and obtain a frozen image with the least amount of movement. There is no deviation and the image is extremely clear.

[Brief explanation of drawings]

1 to 5 show a first embodiment of the present invention.
The figure is an explanatory diagram showing the overall configuration of an imaging device of an electronic endoscope, and FIG. 2 is an explanatory diagram showing signal reading from a solid-state imaging device.
Figure 3(a) is a waveform diagram of the illumination light for the subject, Figure 3(b) is a waveform diagram of the output signal from the CCD, and Figure 3(c) is a waveform diagram of the output signal from the CCD.
is a waveform diagram of the output signal from the field memory, FIG. 4(a) is a waveform diagram showing another aspect of the illumination light for the subject, and FIG. Figure 5 (c) is a waveform diagram of the output signal from the field memory at that time, Figures 5 (a) and (b)
are the waveform diagrams of the signal input to the comparator without going through the IH delay circuit and the signal input to the comparator through the IH delay circuit, respectively, and (C) is the waveform diagram of the output signal from the comparator. FIG. 6(d) is a waveform diagram of the output signal from the waveform processing circuit, FIGS. 6 and 7 show a second embodiment of the present invention, and FIG. FIG. 7(a) is an overall configuration diagram of an electronic endoscope imaging device showing the third embodiment from a comparator, and FIG. 9 is a fourth embodiment of the present invention. 1 is an overall configuration diagram of an image conveying device of an electronic endoscope. 3: Color filter, 5: CCD, 7: Processor, 8: Freeze operation means, 12: Field memory, 1
5: Color encoder, 17: Enable signal control circuit, 20: Analog switch, 21: Shutter control means,
22: Motion detection means, 23.4OR. 40G, 40B, 50R, 50G, 50B:
LH delay circuit, 24, 42.52R, 52G, 52
B: Comparator, 25.53R. 53G, 53B: Waveform processing circuit, 26 two integration circuits,
30: contour pattern change portion detection means, 31: second comparator, 32: second waveform processing circuit, 33: 2H delay circuit, 34: gate circuit. Figure 2

Claims (2)

[Claims] (1) Provided at the tip of the insertion section in an electronic endoscope,
It has a solid-state image sensor that acquires two semi-field image signals with a time difference as image data of each color of R, G, and B, and a field memory that stores each semi-field image signal acquired by the solid-state image sensor. Then, the two semi-field image signals are transferred from the field memory into one.
In an electronic endoscope device that generates composite field image data by alternately reading each line to form a color image using the composite field image data of each color, one line and the next line in the composite field image data a motion detection means for detecting the presence or absence of movement of the subject by comparing the output level difference between the motion detection means;
An image freezing device comprising a switch means for causing a freezing operation. (2) A contour pattern changing section that detects a change in the contour of the image pattern of the subject by detecting the output level difference between one line and the second line from that line in the composite field image data. 2. The image freezing apparatus according to claim 1, further comprising a detecting means, wherein the contour pattern change portion detecting means removes a non-motion signal component included in the detection signal of the motion detecting means.