JP2002291690A - Electronic endoscope apparatus and electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce an optical image with lightness uniform over an entire monitor picture by correcting a luminance signal in an electronic endoscope apparatus. SOLUTION: An image pickup sensor 14 is provided on the top end of a scope 10 and a video signal provided from the image pickup sensor 14 is outputted to a processor 100. The processor 100 generates a video signal on the basis of the provided video signal and corrects a luminance level by a luminance level correcting circuit 130 so that lightness can become uniform on the screen of a monitor device 200. The luminance level correcting circuit 130 controls the level by multiplying correction data read out of an EEPROM 26 of the scope 10 to a luminance value corresponding to each of pixels.

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 provided with a scope formed of a flexible tube and a processor for detachably connecting the scope.

[0002]

2. Description of the Related Art In such an electronic endoscope apparatus,
A CCD image sensor is provided at the tip of the scope, and this CCD image sensor is combined with an objective lens system. A light guide composed of a bundle of optical fibers is inserted through the scope, and illumination light is supplied from the light source lamp in the processor connected to the base end of the scope to the distal end of the scope via the light guide. When the scope is inserted into the patient's body cavity, the front of the objective lens system is illuminated by illumination light emitted from the distal end face of the light guide, and an optical image is formed on the light receiving surface of the CCD image sensor, where electrical signals are generated. Is photoelectrically converted into CCD
An electric signal obtained from the image sensor, that is, a pixel signal is sent to a video signal processing circuit of a processor, and a video signal is generated based on the pixel signal. Further, the video signal is output to a monitor device, where an optical image is reproduced on a monitor screen.

[0003] In order to insert a scope into a body cavity, it is essential to reduce the diameter of an objective lens system or the like. is there. For this reason, a wide-angle lens having a relatively wide field of view is often used as an objective lens system, and the depth of focus is set deep.

However, since the luminance of the illumination light has a distribution characteristic of being high near the center and low in the periphery, even when the field of view is widened, the periphery of the optical image reproduced on the monitor screen becomes dark, and a lesion or the like is found. There was a problem that it was difficult to do.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic endoscope apparatus capable of reproducing an optical image with uniform brightness over the entire monitor screen. It is.

[0006]

An electronic endoscope apparatus according to the present invention includes a solid-state image sensor and correction data for adjusting the luminance value of one frame of a video signal obtained from the solid-state image sensor to a constant level. A scope having memory to hold;
A processor that reads the correction data from the memory and corrects the luminance value of the video signal for one frame obtained from the solid-state imaging device to a level based on the correction data, and a screen that is based on the video signal corrected by the processor. A monitor device for displaying a subject image is provided.

In the electronic endoscope apparatus, the correction data is
It is preferably a set of level correction values that are multiplied by the video signal of each pixel to correct the video signal for one frame to the maximum luminance level.

Further, the electronic endoscope system of the present invention comprises a solid-state image pickup device for picking up a subject image, and correction data for adjusting a luminance value of a video signal for one frame obtained from the solid-state image pickup device to a constant level. A scope having a memory for storing the correction data, a processor for reading out the correction data from the memory, and correcting the luminance value of the video signal for one frame obtained from the solid-state imaging device to a level based on the correction data; A monitor device for displaying a subject image on a screen based on the corrected video signal, and a recording device capable of recording the corrected video signal are provided.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an electronic endoscope system according to the present invention. The electronic endoscope system includes a scope 10 having a flexible tube, and a processor 100 detachable from the scope 10. A light guide member 12 made of an optical fiber bundle is inserted through the scope 10 to the distal end portion 10a of the scope, and a base end of the light guide member 12 is a light source provided on the processor 100 when the scope 10 is mounted on the processor 100. Optically connected to 102. As a result, the illumination light from the light source 102 is guided to the scope tip 10a by the light guide member 12, and the subject in front, for example, the internal organ X, is illuminated.

An image sensor 14 comprising a solid-state image sensor, for example, a CCD, is provided at the scope tip 10a. The image sensor 14 includes an objective lens system combined with the CCD. In the present embodiment, a simultaneous method is adopted to reproduce a color image, and an optical image of a subject illuminated by white illumination light is formed on a light receiving surface of a CCD by an objective lens system. The optical subject image formed on the CCD is photoelectrically converted into an analog video signal for one frame by the imaging sensor 14, and the CCD driving circuit 22 built in the connector section 20 of the scope 10 causes the imaging sensor 14 to perform image conversion.
Are sequentially read out.

An analog video signal read from the image sensor 14 is processed by a primary processing circuit 24 incorporated in the connector section 20 in accordance with the characteristics of the image sensor 14 and the optical characteristics of the scope 10, for example, a clamp process or a sample process. Hold processing, gamma correction processing, white balance correction processing, contour enhancement processing, amplification processing, and the like are performed, and the result is output to the video signal processing circuit 104 of the processor 100. In the video signal processing circuit 104, the analog video signal for one frame is converted into digital signals of three colors of R, G, and B, and each color signal is converted into an R memory 106 and a G memory 10 respectively.
8 and the B memory 110 once.

A horizontal synchronizing signal and a vertical synchronizing signal output from a timing circuit 112 are added to a one-frame three-color digital signal sequentially read from each of the color memories 106, 108 and 110, and a video processing circuit 114.
Sent to The video processing circuit 114 is provided with a low-pass filter that removes high-frequency band components that become noise from the three-color digital signal. The video processing circuit 114 generates an NTSC component digital signal in which a luminance signal and a color difference signal are multiplexed from one frame of the three-color digital signal passed through the low-pass filter.

The component digital signal output from the video processing circuit 114 is output to a luminance level adjusting circuit 130.
After the luminance level is adjusted and converted into an analog color video signal such as an NTSC composite video signal, the monitor device 200 or a recording device 300 such as a VCR is used.
Is output to A subject image is reproduced on the screen based on the analog color video signal in the monitor device 200,
The image is recorded as a still image or a moving image in the recording device 300. A keyboard 400 is connected to the processor 100, and character information such as a patient name and a consultation date and time input from the keyboard 400 is transmitted to the system control circuit 11.
The signal is converted into a character pattern signal by 6 and output to the video processing circuit 114, where it is added to the component digital signal. Thus, the character information is displayed on the screen of the monitor device 200 together with the reproduced image of the optical subject image.

When adjusting the luminance level, the luminance level adjusting circuit 130 reads out correction data from a nonvolatile memory, for example, an EEPROM 26 provided in the connector section 20 of the scope 10, and adjusts the level of the luminance signal for each pixel.
By this brightness level correction processing, the brightness level of the subject image on the monitor screen becomes constant for each frame. That is, the brightness level of the periphery darker than the center of the screen is amplified, and the brightness level is adjusted so that the center and the periphery have the same brightness.

The correction data is a value corresponding to the optical characteristic inherent to the scope 10. Since the scope 10 is composed of high-precision parts, even a small mechanical error greatly affects the optical characteristics of each scope 10.
In the present embodiment, the correction data is provided on the scope 10 side, so that it is not necessary to perform an adjustment operation according to the optical characteristics of each scope 10 on the processor 100 side when the scope 10 is replaced.

Correction data is written in the EEPROM 26 in advance, and this correction data can be rewritten as needed. Rewriting of the correction data is possible only in a master processor (not shown).

The system control circuit 116 is a microcomputer for controlling the entire operation of the processor 100, and includes a CPU, a ROM for storing programs and parameters for executing various routines, and a RAM for temporarily storing data and the like. Prepare. Timing circuit 112
Are the circuits 104, 106, 108, 110, 114,
A clock pulse for synchronizing 116 is output.

The processor 100 is provided with a stop 120 for adjusting the amount of illumination light supplied from the light source 102 to the light guide member 12. The aperture 120 is the aperture adjustment circuit 1
The degree of opening is adjusted by means of 22, whereby the amount of light is adjusted. The iris adjustment circuit 122 includes the video signal processing circuit 10
The average brightness level of the digital video signal for one frame output from the output unit 4 is calculated, and based on the average brightness level, the aperture opening is adjusted to an appropriate value to perform automatic light control.

FIG. 2 is a flowchart showing a luminance level correction processing routine in the luminance level adjustment circuit 130. This process is started when a component digital signal for one frame is input from the video processing circuit 114 to the luminance level adjustment circuit 130.

First, in step S102, a luminance signal generated from the component digital signal is stored in an internal memory (not shown). Then, in step S104, the luminance signal for one frame is divided into K blocks in the horizontal direction. Subsequently, in step S106, EEPRO
Correction data, that is, K correction values α ₁ to α _K are read from M26.

In step S108, 1 is substituted for a parameter n indicating the number of blocks. In step S110, the luminance value of the luminance signal forming the n-th block is read out.
In step S112, each luminance value is multiplied by the correction value αn, and in step S114, the product is stored again in the memory. Thereby, the luminance value is rewritten.

In step S116, it is determined whether or not the value of n has reached the number K of blocks. If not, n is incremented by 1 in step S118, and the process returns to step S110. That is, steps S110 to S110
Step S114 is repeated K times, and the luminance value of the luminance signal for K blocks, that is, for one frame is rewritten.
When the rewriting of the luminance value for one frame is completed, the luminance level correction processing routine ends, and the corrected luminance signal and the color difference signal are multiplexed to generate an analog video signal.

Correction value α₁~ Α_kExplain the criteria
(K / 2) th at the center of the screen when capturing a white plate
If the average luminance value of the block is 255, the corresponding correction
Value α _{(K / 2)}Is set to the reference value 1. And the surrounding bu
Other correction values so that the average brightness value of the lock is 255.
α₁~ Α_{(k / 2-1)}, Α_{(k / 2 + 1)}~ Α_kIs determined. General
The brightness level at the center of the screen is highest, and
Since the brightness level decreases as the size of the block decreases, the correction value
α_{(k / 2)}Is the smallest and the correction corresponding to the blocks at both ends
Value α₁Or α_kThe value gradually increases toward.

As described above, by adjusting the luminance level of the luminance signal, the luminance of the peripheral portion, which tends to be dark on the monitor screen, can be improved, the affected part can be detected early, the consultation time is reduced, and the burden on the patient is reduced. Decrease. Further, since the correction data is held by the scope 10, even if it is replaced with another scope, correction data corresponding to the scope can be obtained, and appropriate level adjustment can be performed.

[0026]

As described above, the electronic endoscope apparatus of the present invention can reproduce an optical image with uniform brightness over the entire monitor screen by correcting the luminance signal.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an electronic endoscope system according to the present invention.

FIG. 2 is a flowchart showing an operation of the luminance level adjusting circuit shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 scope 14 imaging sensor 26 EEPROM 100 processor 130 brightness level adjusting circuit 200 monitor device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H040 GA02 GA06 GA11 4C061 CC06 NN05 SS21 TT01 WW09 5C022 AA09 AB12 AC42 AC51 AC69 CA00 5C054 AA04 CA04 CC07 EA01 EB05 EB07 EC06 ED11 EJ01 FB03 HA12

Claims (3)

[Claims] 1. A scope comprising: a solid-state imaging device; a memory for holding correction data for adjusting a brightness value of a video signal for one frame obtained from the solid-state imaging device to a constant level; While reading out the correction data,
A processor that corrects the luminance value of the video signal for one frame obtained from the solid-state imaging device to the level based on the correction data, based on the video signal corrected by the processor,
An electronic endoscope apparatus comprising: a monitor device that displays the subject image on a screen. 2. The apparatus according to claim 1, wherein the correction data is a set of level correction values that are multiplied by the video signal of each pixel to correct the video signal of one frame to a maximum luminance level. The electronic endoscope device according to claim 1. 3. A scope comprising: a solid-state imaging device for capturing a subject image; and a memory for holding correction data for adjusting a luminance value of a video signal for one frame obtained from the solid-state imaging device to a constant level. Reading the correction data from the memory,
A processor that corrects the luminance value of the video signal for one frame obtained from the solid-state imaging device to the level based on the correction data, based on the video signal corrected by the processor,
An electronic endoscope system comprising: a monitor device that displays the subject image on a screen; and a recording device that can record the corrected video signal.