JP3494569B2 - Electronic endoscope device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly, to a method of forming a moving image by a conventional pixel-mixed readout method.
The present invention relates to a configuration of an electronic endoscope apparatus that reads out all pixels stored in an image sensor and forms a still image. 2. Description of the Related Art In an electronic endoscope apparatus, for example, a CCD (Charge Coupled Device) is used as a solid-state image pickup device. In this CCD, charges stored in pixels are read out by a photoelectric conversion element. Thus, an image signal (video signal) is obtained. And
For example, in a simultaneous type electronic endoscope apparatus, a color filter is arranged in pixel units on the upper surface of the CCD, thereby obtaining a color image. FIG. 7 shows the arrangement of the above color filters. As shown in the drawing, for example, Mg (magenta), Cy (cyan) pixels, G (green) and Ye (yellow) pixels are arranged in odd lines. In the CCD 1, accumulated charges (pixel signals) in pixel units are passed through these color filters.
Is obtained. [0004] According to the conventional color difference line sequential mixed reading method, the accumulated charges of the pixels on the upper and lower lines are added and mixed and read. For example, at the first exposure, a mixed signal of 0 line and 1 line, a mixed signal of 2 lines and 3 lines,
.. Are read out, and a mixed signal of 1 line and 2 lines, a mixed signal of 3 lines and 4 lines, and so on in the second exposure are read out. The video signal is read. Therefore, a mixed signal of two lines of the CCD 1 becomes a signal of one line of the field image, and one or more odd or even data of one field can be obtained by one exposure. FIG. 8 shows the operation of a signal read from the CCD 1. In the electronic endoscope apparatus, as shown in FIG. 1A, 1/60 second (vertical synchronization period)
An odd field and an even field are formed based on each O (Odd) / E (Even) signal (field signal). Therefore, as shown in FIG. 3B, signal accumulation is performed according to the accumulation (exposure) time T of the electronic shutter during the 1/60 second period, and the accumulated mixed signal is accumulated in the next 1/60 second period. Is read. As a result, as shown in FIG. 7C, an odd (Odd) field signal and an even (Even) field signal are obtained. For example, the (n-1) th odd field signal is shown on the left side of FIG. (0 + 1) line, (2 + 3) line, (4+
5) A mixed signal of lines..., And the n-th even-numbered field signal includes (1 + 2) lines and (3) shown on the right side of FIG.
+4) It becomes a mixed signal of lines. [0006] The odd field signal and the even field signal are interlaced and formed as an image of one frame, and the image is displayed as a moving image on a monitor. Further, in the endoscope apparatus, a freeze switch is arranged on the operation unit, and when the freeze switch is pressed, a still image at that time is formed and displayed. However, in the above-mentioned simultaneous electronic endoscope apparatus, as shown in FIG. 8C, an odd field image for forming one frame image and an odd field image for forming one frame image are used. 1/60 between even field images
If there is a time lag of seconds and the endoscope itself shakes or the movement of the observed object during this time, there is a problem that the image quality (resolution, color shift, etc.) is deteriorated when displaying a still image. .
That is, in the case of a moving image, it is often better to faithfully reproduce the movement of the subject or the like by the above-described mixed reading method in the CCD 1, but in the case of a still image, the resolution is reduced. Further, the electronic endoscope apparatus often employs an electronic shutter function for changing a signal accumulation time. According to this, if the accumulation time is shortened in a bright place at a short distance, the image quality is improved. Can be planned. However, as shown in FIG.
There is a time lag of 1/60 second between accumulations (exposures), and there is also a disadvantage that the effect of shortening the accumulation time cannot be sufficiently enjoyed in a still image. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to read out all pixels obtained by an image sensor by one exposure to form a high-quality still image. It is another object of the present invention to provide an electronic endoscope apparatus capable of faithfully reproducing a motion and preventing an incomplete image from being displayed when switching from a moving image to a still image. In order to achieve the above object, the present invention provides an image pickup device which mixes and outputs pixel signals stored in an image pickup device between upper and lower lines to form a moving image. A mixed pixel readout method and an all-pixel readout method for reading out the signals of all the pixels stored in the image sensor in one exposure using the light-shielding period set by the light-shielding means and forming a still image. An electronic endoscope apparatus, wherein all the pixels are read out.
When executing the scanning method, the odd line obtained from the image sensor is used.
And the image signal of the even line are stored.
When executing the above-described all-pixel reading method,
The image signal of the predetermined line previously stored in the
Phase adjustment memo to make the image signal of the
And the same exposure read from each of the above memories.
The pixel signals of the odd line and the even line are added and mixed.
Combination circuit that forms a one-field still image signal
And the pixel mixed reading method output from the image sensor.
Delay video signal by at least one frame processing period
Delay means (delay memory) and output from this delay means
Video signal and the still image signal output from the mixing circuit
Image that switches the number based on the operation of the freeze switch
And a switching circuit . According to the above arrangement, when the freeze switch is pressed, the all-pixel reading method is selected, thereby forming a still image. For example, the charge accumulated by exposure (exposure time is arbitrary) within a predetermined (first) 1/60 second period (vertical synchronization period) is imaged in a second period (1/60 second). The odd lines of the element (CCD) are read and stored in a predetermined memory (read from the transfer line), and the remaining even lines are read in a third (at the next exposure) period, which is also stored in the predetermined memory. It is memorized. Then, in order to be able to read out the even-numbered lines, the light source light in the second period is blocked by the light blocking means. That is, if the charges of the next exposure are accumulated during the second period for sequentially reading the accumulated charges of the odd-numbered lines, the remaining even-numbered lines cannot be read. Therefore, in the present invention, the light output in the second period is eliminated, and the accumulated charges in the even-numbered lines are read in the third period. As a result, signals for all pixels of the image sensor obtained by one exposure can be read. Next, the video signal of, for example, the odd line first stored in the above memory is further stored in the phase adjustment memory and delayed by 1/60 second, and thereafter, the odd line and the odd line are mixed by the mixing circuit. A pixel mixing process is performed with the data of the even-numbered lines. That is, this pixel mixing process
As a result, a signal equivalent to the pixel mixture readout method at the time of output of the image sensor, which is performed at the time of signal output from the image sensor, is formed, but the pixel mixture is performed based on information obtained in one exposure. This is distinguished from the pixel mixed readout method at the time of element output. Then, the video signals of the odd field and the even field are formed by the pixel mixture signal, and a still picture is displayed based on these video signals. Therefore, a still image is formed based on signals of all pixels obtained by one exposure, and becomes a high-quality image. On the other hand, in the normal state in which the freeze switch is not pressed, the pixel mixture readout method at the time of output of the image pickup device is selected, and pixels of two horizontal lines read from the image pickup device are mixed and output as in the conventional case. Is done. However, when switching from a moving image to a still image, the illumination light is blocked and switching to reading of all pixels is performed. The processing is performed, and a phenomenon occurs in which an incomplete image (an image with half luminance and an inappropriate color) is displayed. Therefore, in the present invention, for example, the moving image data is totally delayed by the processing time for one frame by the delay memory so that the moving image data is not formed by the image data obtained at the time of light shielding. This prevents display of an inappropriate image that occurs when switching from a moving image to a still image. FIG. 1 shows a circuit configuration of an electronic endoscope apparatus as an example of an embodiment. This electronic endoscope apparatus has a scope (electronic endoscope) 10. Is connected to a processor device or a light source device having an image processing circuit. The scope 10 is provided with a CCD 12 having a color filter similar to that described with reference to FIG. 7 at its distal end, and a light guide 15 for guiding the light of the light source 14 to the distal end. The operation unit of the scope 10 has a freeze switch 16 for displaying a still image.
Is provided. A CCD driving circuit 18 for driving the CCD 12 is connected to the CCD 12, and a timing generator 19 and a microcomputer (microcomputer) 20 are connected to the driving circuit 18, and the freeze is connected to the microcomputer 20. An operation signal of the switch 16 is input. The CCD drive circuit 18 inputs a timing signal based on the control of the microcomputer 20, and performs drive control of a mixed pixel readout method at the time of CCD output for a moving image and an all pixel readout method for a still image. For example, in the case of this all-pixel reading method,
Two types of pulses for reading out the accumulated data for all pixels accumulated in the CCD 12 in one exposure by dividing the data into odd lines and even lines (shifted in terms of time) are also used for the CCD.
The signal is supplied from the drive circuit 18, and based on the signal, the control for sequentially and sequentially reading the odd-line signal and the even-line signal from the CCD 12 is performed. Note that in the pixel mixed reading method at the time of CCD output, one type of reading pulse is applied to each line. An A / D converter 22 for inputting the output signal of the CCD 12 is provided.
In the subsequent stage, a first memory 23 for storing the image data of the odd lines, a second memory 24 for storing the image data of the even lines, and the first memory 2 for reading all the pixels.
3 is stored as it is, and the read timing is set to 1
Third memory 2 for phase adjustment for delaying by / 60 seconds
5. A still image mixing circuit 26 is provided. That is, CCD
All the pixel signals obtained in step 12 are divided into odd-line data (video signals) and even-line data.
Once stored in the respective memories 23 and 24, the first
By delaying the odd-numbered line data in the memory 23 by 1/60 second, it becomes the same phase as the even-numbered line data stored in the second memory 24. As a result, both image data can be read at the same time, and the next-stage mixing circuit 26 adds and mixes the pixel data of the odd-numbered line of the third memory 25 and the pixel data of the even-numbered line of the second memory 24. (Still image pixel mixing process). Therefore, in the case of a still image, a pixel mixture signal equivalent to that of the conventional color difference line sequential mixture readout system is formed by the mixing circuit 26. FIG. 2 shows the contents of still image data formed by the circuits from the CCD 12 to the mixing circuit 26 described above. As shown in FIG. 1A, the CCD 12 is provided with horizontal lines from 0 to N lines corresponding to the number of scanning lines, and the pixel data of the horizontal lines is transferred to a transfer line and read. Is done. The data of the odd lines (1, 3, 5,...) Of the CCD 12 are stored in the first memory 23 (and the third memory 25) of FIG. Are stored in the second memory 24 in FIG. The data in the memories 25 and 24 are mixed by the mixing circuit 26 as described above, as shown in FIGS.
, Pixels are mixed with each other, and as shown in FIG. 3D, 0 line + 1 line, 2 line + 3 line, 4 line
The addition operation data of line + 5 lines ... is odd (Odd)
Output as field data. Further, in a state where the read line in FIG.
1), pixel mixing is performed between the lines in FIG. 9B and the line, and as shown in FIG.
2 lines, 3 lines + 4 lines, 5 lines + 6 lines ...
Is output as even field data. In this example, the odd number of lines of the CCD 12 is ODD, the even number is EVEN, the odd number of the field to be interlaced is Odd, and the even number is Ev.
en. Further, as shown in FIG.
A sixth memory 27A and a seventh memory 27B are connected to the other output line of the converter 22 as a delay memory for moving image data. That is, in this example, the CCD 12
The two memories 27A and 27B delay the moving image data by one frame (two fields), that is, 1/30 second in terms of time, so that an incomplete moving image is not formed by the still image data obtained in step (1). Thereby, at the timing when the incomplete still image data is displayed as a moving image, the still image is switched and displayed, and the display of the incomplete moving image is avoided. The seventh memory 27B and the mixing circuit 2
6 is connected to an image switching circuit 28 for switching between a moving image and a still image. When the freeze switch 16 is pressed, the image switching circuit 28 switches from the terminal a to the terminal b under the control of the microcomputer 20. A DVP (Digital Video Processor) 29 is connected to the image switching circuit 28. In the DVP 29, color signal processing is performed by the same pixel mixing and reading method as in the related art, for example, a color difference signal and a luminance signal are formed. Then, control of the image position, enlargement processing, and the like are also performed. At the subsequent stage of the DVP 29, a fourth memory 3 for storing data of odd-numbered fields and even-numbered fields is provided.
A zero and fifth memory 31, a switching circuit 32, and a D / A converter 33 are provided. For example, in the case of a still image, odd field data obtained by converting the data of FIG. 2D into a color difference signal or the like is stored in the fourth memory 30, and the fifth memory 31 stores the odd field data of FIG. Even field data in which the data is converted into a color difference signal or the like is stored. On the other hand, the light source section for supplying light to the light guide 15 provided on the scope 10 has the light source 14
A stop 35 and a light blocking plate 36 are arranged between the light guide 15 and the light guide 15. The light-shielding plate 36 is configured to rotate, for example, a semicircular plate, and a driving circuit 38 is connected to rotate the light-shielding plate 36. In this example, the light shielding plate 36 is used by the freeze switch 16 in the field O / E signal in a cycle every 1/60 second.
The light is blocked for a predetermined 1/60 second after the is pressed. The diaphragm 35 has a diaphragm control circuit 3
9. A lamp drive circuit 40 is connected to the light source 14, and the aperture control circuit 39 drives the aperture 35 based on the luminance signal obtained by the DVP 29 to adjust the output light amount of the light source 14. ing. This example has the above-mentioned configuration, and its operation will be described with reference to FIGS. 3 to 6 (each figure coincides in time at point Q). As shown in FIG. 3B, a timing signal for forming a one-field image in 1/60 second is used as a field O (Odd) / E (Even) signal, as in the related art. In the normal state, it is set so as to execute the moving image processing, that is, the pixel mixture readout method at the time of CCD output. The light shielding plate 36 shown in FIG.
Irradiated from the tip into the body to be observed via the. By this light irradiation, an image of the inside of the object to be observed is captured by the CCD 12 at the distal end, and charges corresponding to the image light are accumulated in the CCD 12. This accumulated charge is read out by adding the pixels between the upper and lower lines by a drive pulse from the CCD drive circuit 18 and reading out the pixel mixture signal described with reference to FIG. The subsequent moving image processing will be described later, and the still image processing will be described first. Freeze switch 1 of scope 10 in FIG.
When the button 6 is pressed, the microcomputer 20 switches the image switching circuit 28 to the terminal b, and switches from the mixed pixel reading method to the all pixel reading method for a still image. For example, as shown in FIG. 3A, if a trigger Tr1 (or Tr2) by the freeze switch 16 is given, as shown in FIG.
Only for 1/60 second from the rise of the / E signal (t1),
The light-shielding plate 36 blocks the optical path, during which the light is blocked [FIG. 3 (D)]. Therefore, the image data from which all the pixels are read out is one-sixth of the data before the light-shielded period.
The electric charge stored in the CCD 12 is obtained by the light output Lt during the period of 0 second. This charge is obtained by the exposure of the electronic shutter pulse g1 in FIG. 3G, and the charges (data) of all the pixels are read out by the CCD drive circuit 18. That is, FIG. 3E shows the read pulse P1 of the odd-numbered line shown in FIG. 2B, and FIG. 3F shows the read pulse P1 shown in FIG.
The read pulse P2 of the even-numbered line shown in FIG. 4A, and the read pulse P1 without the pulse at t2 and the read pulse P2 without the pulse at t1, as shown in FIG.
Odd (ODD) line data and even (EV)
EN) Line data is sequentially read. Therefore, the reading of the odd-numbered lines is performed during the light-shielding period (t1 to t2), and the reading of the even-numbered lines is performed during the next period (t2 to t3). As shown in FIG. 3 (G), there is no rising period (sweep period) between the above-mentioned t1 and t2 even in the electronic shutter pulse. The odd line data is stored in the first memory 2 as shown in FIG.
3 and the even line data is written to the second memory 24 as shown in FIG. Next, FIG.
As shown in (E), the odd-numbered line data of the first memory 23 and the even-numbered line data of the second memory 24 are read twice, and the odd-numbered line data is 1/60.
It is stored in the third memory 25 to adjust the phase of the second. Therefore, as understood from FIGS. 4E and 4F, the data of the odd-numbered lines and the data of the even-numbered lines are aligned with the same phase (timing). Each data read out from the memories 25 and 24 in this manner is subjected to pixel mixing by the mixing circuit 26. In this example, in order to enable this, FIG.
As shown in (G), the first memory 23 and the second memory 24 are write-protected. Then, pixel mixture conversion is performed in the same period [FIG. 4 (H)], and first, as shown in FIG.
0 line + 1 line, 2 line + 3 line, 4 line +
Output data of 5 lines... Is output, and this is an odd number (Od).
d) It is stored in the fourth memory 30 as field data [FIG. 4 (I)]. Next, the addition data of 1 line + 2 lines, 3 lines + 4 lines, 5 lines + 6 lines... Shown in FIG. 2E is output, and this is an even number (Even).
The data is stored in the fifth memory 31 as field data. Then, at the same time as reading out the odd field data and the even field data, the switching circuit 32 outputs the respective field data alternately as shown in FIGS. 4 (K) and (L). The fourth memory 30 and the fifth memory 31 are selected. These field data are
The data is output to a monitor via the D / A converter 33, and an image is displayed on the monitor by interlaced scanning. As a result, a still image is displayed based on all pixel data obtained at the same exposure, and a high-quality image is obtained. Therefore, even if the endoscope itself shakes or the subject moves for 1/60 second, it is possible to observe a clear still image with a small influence. However, in the above-described still image processing, all the pixel data is read out during the two-field period after the one-field period is shielded, so that the display is delayed by one frame as compared with the case of the moving image. Become. Therefore, when the moving image data is used as it is without using the delay memories (27A, 27B), there is a disadvantage that the moving image is displayed by incomplete still image data immediately before switching to the still image. FIG. 5 shows a state of such moving image processing. For example, O1 (O / E) shown in FIG.
Signal), the odd line data O11 and the even line data O12 shown in FIGS.
The moving image data output from the CCD 12 is O11 + O12 as shown in FIG.
It is stored in the memory 31 and is read out and supplied to the monitor during the period shown in FIG. E1 and O2 in FIG.
In the same period, data of E11 + E12 and O21 + O22 are output to the monitor. However, the next E2 (tO to t) shown in FIG.
1), during the period of O3 (t1 to t2), light is shielded during this period of O3 and all pixels are read out.
As shown in (C), only odd-numbered line data F1 (ODD line) is obtained during the period of E2, and
In this period, only even line data F2 (EVEN line) is obtained. These data F1 and F2 are also used as field data of a moving image immediately before a still image is displayed as shown in FIGS. These data F1 and F2 are normal field data (such as luminance).
Is unprocessed data, and the moving image at this time does not hold as an image. Therefore, in this example, the sixth memory 27A and the seventh memory 27B are arranged so that the moving image data is delayed by a processing period of one frame so that the data F1 and F2 are not used as a moving image. This processing state is shown in FIG.
Is shown in At the time of this moving image formation, the image switching circuit 28 is switched to the terminal a side, and the image signal is subjected to predetermined processing by the DVP 29 in the same manner as in the case of the still image, and then stored in the fourth memory 30 at the subsequent stage. Odd field data is stored in the field data and the fifth memory 31. In FIG. 6, the odd line data O11 [FIG. (B)] and the even line data O12 [FIG. (C)] obtained during the period of O1 (O / E signal) in FIG. As shown in (D), the delay is delayed by one field (1/60 second) in the sixth memory 27A, and further delayed by one field in the seventh memory 27B as shown in (E). Therefore,
O11 + O12 read from the seventh memory 27B [FIG. (F)] and serving as moving image data is compared with the case of FIG.
The time is delayed by one frame (1/30 second). This is because E11 + E obtained in the next period of E2 and O3.
12, the same applies to O21 + O22, and all the moving image data is delayed by one frame. Therefore, as shown in FIG. 6 (H), in FIG. 5, the above-mentioned E11 + E12 is used during the period (E3) during which the still picture data F1 is extracted, and as shown in FIG. 6 (I) In FIG. 5, the period during which the still image data F2 is extracted (O3
) Uses the above O21 + O22. As a result, the still image data F1 and F2 are not used as moving image data, and incomplete moving image display is avoided. In the above embodiment, the memories 27A and 27B are used as delay means, but other delay means may be used. In the above example, the delay time is set to one frame. However, in the case of processing at a different timing, the delay time may be set to one field, three fields, two frames, or the like. As described above, according to the present invention,
An electronic endoscope that forms a still image by an all-pixel readout method in which a moving image is formed by a pixel-mixing readout method at the time of output of an imaging device and signals of all pixels stored in the imaging device are read by one exposure while setting a light-shielding period. The mirror device uses a delay means such as a memory to reduce the amount of moving image data obtained by the pixel readout method.
At least one frame of processing time is delayed, so that for moving images, a smooth image that faithfully reproduces the motion can be obtained, while for still images, high-quality images without blurring can be obtained. There is an advantage that incomplete images are not displayed at the time of switching.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a circuit configuration of an electronic endoscope apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing image data read from the CCD of FIG. 1 to a mixing circuit. FIG. 3 is an explanatory diagram showing a still image forming operation in the embodiment. FIG. 4 is an explanatory diagram showing a still image forming operation in the embodiment and continuing from FIG. 3; FIG. 5 is an explanatory diagram showing a moving image forming operation when no delay memory is provided in the embodiment. FIG. 6 is an explanatory diagram showing a moving image forming operation in the embodiment. FIG. 7 is a diagram illustrating a configuration of a color filter in a conventional CCD and pixel mixture readout. FIG. 8 is an explanatory diagram showing an operation in a conventional CCD. [Description of Signs] 1,12 CCD, 10 scope, 16
Freeze switch, 18 CCD drive circuit, 20
... microcomputer, 23 ... first memory, 24 ...
Second memory, 25... Phase adjustment (third) memory, 26
… Mixed circuit, 27A, 27B… delay memory,
28 ... image switching circuit, 30, 31 ... memory,
36: light shielding plate, 38: light shielding plate driving circuit.

(56) References JP-A-7-236636 (JP, A) JP-A-9-18792 (JP, A) JP-A-9-90244 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) A61B 1/00

Claims (1)

(57) [Claims] 1. Pixels stored in an image sensorsignalUp and down la
Image sensor output that mixes and outputs moving image data to form a moving image
Pixel mixed readout method and one exposure to the above image sensor
The signal of all the stored pixels is shaded by the shading means set by the shading means.
Read all pixels to form a still image
An electronic endoscope device having a method,When executing the above all-pixel reading method, the
The odd-numbered line image signal and the even-numbered line image
A memory for storing signals, When executing the all-pixel reading method, the memory
The stored image signal of a predetermined line and the image signal of another line are stored.
Phase adjustment memory for aligning signals with the same phase, The odd number at the same exposure read from each of the above memories
Add and mix the pixel signals of the line and the even line
A mixing circuit for forming a one-field still image signal; Pixel-mixed read-out video output from the image sensor
Delay the signal by at least one frame processing period
Delay means; The moving picture signal output from the delay means and the mixed circuit
The still image signal output from the
And an image switching circuit for switching based on Electronic
Endoscope device.