JPH11216108A - Electronic endoscope unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a static image with high picture quality by reading out all pixels, reproduce a moving image faithfully an prevent an imperfect image from being displayed on switching the moving image to static image. SOLUTION: For static image, in all pixels got in one exposure with CCD 12, odd line signal and even line signal are read out in sequence. And the data of odd line and even line is output to a mixed circuit 26 via the first memory 23, the second memory 24 and a phase adjustment memory 25 then the mixed pixel signal is formed on it. Thus a static image that is high picture quality is obtained. On the other hand, for a moving image, the mixed pixel data is output from CCD 12 to reproduce it with fidelity. Those image data are stored temporally in the forth memory 30 and the fifth memory 31 and output to a monitor. And unfinished data that has got in the all pixel read out system is not written on the forth memory 30 and the fifth memory 31 on displaying moving image. Thus an imperfect image, which occurs just before the switching, goes away.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly, to a method for forming a moving image by a conventional pixel-mixed reading 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.

[0002]

2. Description of the Related Art In an electronic endoscope device, for example, a CCD (Charge Coupled Device) is used as a solid-state image pickup device. It is configured to obtain a signal (video signal). And
For example, in a simultaneous electronic endoscope device, 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 figure, for example, Mg (magenta), Cy (cyan) pixels, G (green) and Ye (yellow) pixels are arranged on 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, the mixed signal of the two lines of the CCD 1 becomes a signal of one line of the field image, and odd or even one field data 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 has (1 + 2) lines and (3) shown on the right side of FIG.
+4) 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 this image is displayed as a moving image on a monitor. Further, in the endoscope apparatus, a freeze switch is disposed on the operation unit, and when the freeze switch is pressed, a still image at that time is formed and displayed.

[0007]

However, in the simultaneous electronic endoscope apparatus, as shown in FIG. 8C, an odd field image and an even field image for forming one frame image are provided. Between 1/60
If there is a time lag of seconds and the endoscope itself shakes or the object moves during this time, there is a problem that when displaying a still image, the image quality (resolution, color shift, etc.) is reduced. .
In other words, in the case of a moving image, it is often better to faithfully reproduce the movement of a 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.

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 pickup device by one exposure to form a high-quality still image, and An object of the present invention is 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.

[0009]

In order to achieve the above object, the present invention provides an image pickup device which mixes and outputs pixels accumulated in an image pickup device between upper and lower lines (horizontal 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 accumulated 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 at least the memory for storing the moving image data, and the still image data read from the imaging element when the all-pixel reading method is selected is not written to the memory as moving image data. And write-inhibiting control means. As a detailed configuration, for example, for all the pixel signals accumulated in the image sensor by one exposure,
An image sensor driving circuit that reads out an image signal of any of odd or even lines first, and then controls to read image signals of the remaining lines. A pre-stage (still image data) memory for storing the odd-line image signal and the even-line image signal, and an image of a predetermined line previously stored in the front stage memory when the all-pixel reading method is executed. A phase adjustment memory for adjusting the phase of the signal and the image signal of the other line, and a pixel image of the odd line and the even line read at the same exposure read from each of the memories and mixed to form a still image A mixing circuit for forming a signal; a moving image signal of the pixel mixing and reading method output from the image sensor and a still image signal output from the mixing circuit based on an operation of a freeze switch. Image switching circuit, a subsequent memory for storing moving image data and still image data output from the image switching circuit, and data for a still image read from the image sensor is written to the latter memory as moving image data. And a control circuit for preventing the occurrence of the error.

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, charges accumulated by exposure (exposure time is arbitrary) within a predetermined (first) 1/60 second period (vertical synchronization period) are 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. Thus, 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-mentioned memory is further stored in the phase adjustment memory and is delayed by 1/60 second. 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 is mixed based on information obtained in one exposure. This is distinguished from the pixel mixed readout method at the time of element output.

[0013] Odd and even field signals are formed by the pixel mixture signal, and a still image 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 a normal state in which the freeze switch is not pressed, the pixel mixture readout method at the time of output of the image sensor is selected, and pixels of two horizontal lines read from the image sensor are mixed and output as in the related art.

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.
In a frame, image processing is performed on half the normal moving image data, 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, a write inhibit signal is output to the subsequent memory for storing moving image data, and the still image data obtained by the all-pixel reading method is not written to the memory as moving image data. Control. According to this, the immediately preceding moving image data that has already been obtained is used again instead of the incomplete data, and display of an inappropriate image that occurs when switching to a still image is prevented.

[0016]

FIG. 1 shows a circuit configuration of an electronic endoscope apparatus as an example of an embodiment. In this electronic endoscope apparatus, a scope (electronic endoscope) 10 is used to display an image. It is configured to be connected to a processor device having a processing circuit or a light source device. 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 drive circuit 18 for driving the CCD 12 is connected to the CCD 12. The drive circuit 18 includes a timing generator 19 and memories (23 to 25,
A microcomputer (microcomputer-control means) 20 for performing various controls including writing and reading of (30, 31) is connected, and an operation signal of the freeze switch 16 is input to the microcomputer 20. The CCD drive circuit 18
Receives a timing signal based on the control of the microcomputer 20, and performs a pixel-mixing reading method at the time of CCD output for a moving image;
The driving control of the all-pixel reading method for a still image is performed.

For example, in the case of this all-pixel reading method,
Two kinds of pulses for reading out the accumulated data for all the 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, control for sequentially reading out the odd-line signal and the even-line signal separately from the CCD 12 is performed. Incidentally, in the pixel mixed readout method at the time of CCD output, one kind of readout 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
/ 3 second memory 2 for phase adjustment for delaying by 60 seconds
5. A still image mixing circuit 26 is provided. That is, CCD
All 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
The odd line data in the memory 23 is delayed by 1/60 second to have the same phase as the even 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 corresponding to the number of scanning lines, and the pixel data of this horizontal line 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. 4D, 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 the state where the read line in FIG.
1), pixel mixture is performed between the lines in FIG. (B) and FIG. (E), 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.
It is distinguished as en.

In FIG. 1, an image switching circuit 28 for switching between a moving image and a still image is provided at a stage subsequent to the mixing circuit 26. In the image switching circuit 28, the A / D terminal for forming a moving image is provided at its a terminal. The output of the converter 22 is supplied via the L line, the output of the mixing circuit 26 is given to the other terminal b, and when the freeze switch 16 is pressed, the microcomputer 20 controls the terminal b to the terminal b. Switch to terminal. The image switching circuit 28 includes a DVP
(Digital video processor) 29 is connected,
In the DVP 29, color signal processing is performed by the same pixel mixture readout method as in the related art, and for example, a color difference signal and a luminance signal are formed.

In the subsequent stage of the DVP 29, a fourth memory 3 for storing data of odd fields and even 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-number (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 of FIG. Even field data in which the data is converted into a color difference signal or the like is stored.

Then, the fourth and fifth memories 30, 3
In step 1, the microcomputer 20 provides a control signal for prohibiting writing for a predetermined period so that unprocessed (unprocessed) still image data is not used as moving image data stored therein. That is, a write signal is set to the memories 30 and 31 in which the incomplete still image data obtained by the all-pixel readout method is write-inhibited during a period when the data is used as a moving image.

On the other hand, in the light source section for supplying light to the light guide 15 disposed on the scope 10, the light source 14
A stop 35 and a light shielding plate 36 are arranged between the light guide 15 and the entrance end of 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 drive the light-shielding plate 36 to rotate. In this example, the light-shielding plate 36 is used by the freeze switch 16 in the field O / E signal at a cycle of 1/60 second.
The light is blocked for a predetermined 1/60 second after the is pressed.

The diaphragm 35 has an aperture control circuit 3
9. A lamp driving 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 is constituted as described above, 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 the CCD 12 accumulates electric charges corresponding to the image light. The accumulated charges are read out by adding the pixels between the upper and lower lines by the driving pulse from the CCD driving circuit 18, and the pixel mixed signal described with reference to FIG. 7 is output. 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. 3C, at the next rising edge of the O / E signal (t1). ), The light shielding plate 36 blocks the optical path only for 1/60 second, during which the light is blocked [FIG. 3 (D)]. Therefore, the image data from which all the pixels are read out are the electric charges accumulated in the CCD 12 with the light output Lt in the 1/60 second period before the light-shielded period.
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 line shown in FIG. 2B, and FIG. 3F shows the read pulse P1 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). Note that, as shown in FIG. 3G, even in the electronic shutter pulse, there is no rising period (sweep period) between the above-mentioned t1 and t2.

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 line data of the first memory 23 and the even line data of the second memory 24 are read twice, and the odd line data is
It is stored in the third memory 25 for adjusting 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 in the same phase (timing).

Each data read out from the memories 25 and 24 in this way 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. 2 (E) is output, and this is an even number (Even).
The data is stored in the fifth memory 31 as field data.

At the same time that the odd field data and the even field data are read, the switching circuit 32 outputs the respective field data alternately as shown in FIGS. 4 (K) and 4 (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 object to be observed 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, there is an inconvenience that a moving image is displayed by incomplete still image data immediately before switching to a 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 manner, the 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), all pixels are read out while being shielded from light during this period of O3.
As shown in (C), only the odd-numbered line data F1 (ODD line) is obtained during the period E2,
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).
, And the moving image at this time does not hold as an image.

Therefore, in this example, a write-inhibit signal is output to the memory for storing the moving image data, so that the data F1 and F2 for one frame are not used as a moving image. As shown in FIG.
At the time of this moving image formation, the image switching circuit 28 is switched to the terminal a side, and the video signal is subjected to predetermined processing by the DVP 29 as in the case of the still image, and then stored in the fourth memory 30 at the subsequent stage. Field data, fifth memory 31
Stores odd field data.

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 pixel mixture readout is performed by the CCD 12, and an image signal is formed based on these signals. In the write signal to the fourth memory 30 at the subsequent stage, the write inhibit period S1 shown in FIG. 7E is set, and in the write signal to the fifth memory 31, the write inhibit period S2 shown in FIG. The unprocessed still image data F1 and F2 are not written to the fourth and fifth memories 30 and 31.

Then, as shown in FIG.
The data of E11 + E12 is read twice from the fourth memory 30, and the data of O21 + O22 is also read twice from the fifth memory 31. Accordingly, in FIG. 5, the data of E11 + E12 is used during the period (E3) during which the still image data F1 is extracted, and the period (O3) during which the still image data F2 is extracted.
) Uses the above data of 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 write inhibit period is one frame in total. However, in the case of processing at a different timing, the write inhibit period is appropriately set accordingly.

[0042]

As described above, according to the present invention,
An electronic endoscope apparatus that forms a moving image by the pixel-mixing readout method at the time of output of the image sensor and forms a still image by the all-pixel readout method that reads out signals of all pixels stored in the image sensor. Is not written to the memory as moving image data, so that for moving images, smooth images with faithful reproduction of 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 illustrating 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 a continuation of FIG. 3;

FIG. 5 is an explanatory diagram showing a moving image forming operation when writing is not prohibited 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.

[Explanation of symbols]

1,12 ... CCD, 10 ... scope, 16 ...
Freeze switch, 18 ... CCD drive circuit, 20
... microcomputer (control means), 23 ... first memory,
24 ... second memory, 25 ... phase adjustment (third)
Memory, 26: mixing circuit, 28: image switching circuit, 30: fourth memory, 31: fifth memory,
36 ... Light shield plate.

[Procedure amendment]

[Submission date] December 8, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

Claims (1)

[Claims] 1. An image-capturing-element-output pixel-mixing readout method for mixing and outputting pixels accumulated in an image sensor between upper and lower lines to form a moving image, An electronic endoscope device including an all-pixel reading method for reading a pixel signal using a light-shielding period set by a light-shielding unit and forming a still image, wherein at least a memory that stores the moving image data; Write-inhibiting control means for preventing the still image data read from the image sensor from being written to the memory as moving image data when the all-pixel reading method is selected;
An electronic endoscope device comprising: