JP4786813B2 - Electronic endoscope apparatus and electronic endoscope system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus including a scope made of a flexible tube and a processor for detachably connecting the scope.
[0002]
[Prior art]
In such an electronic endoscope apparatus, a CCD image sensor is provided at the tip of a scope, and this CCD image sensor is combined with an objective lens system.
A light guide made of an optical fiber bundle is inserted into the scope, and illumination light is supplied from the light source lamp in the processor connected to the proximal end side of the scope to the distal end of the scope through the light guide. When the scope is inserted into the body cavity of the patient, the front of the objective lens system is illuminated by illumination light emitted from the end surface on the distal end side of the light guide, and an optical image is formed on the light receiving surface of the CCD image sensor, where an electrical signal is generated. To photoelectric conversion. An electrical signal obtained from the CCD 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 the monitor device, where an optical image is reproduced on the monitor screen.
[0003]
In the video signal processing circuit, the pixel signal is subjected to white balance processing. Specifically, correction coefficient data in which the levels of R, G, and B are 1: 1: 1 is set in advance, and based on the correction coefficient data. Thus, the signal level of each color of the pixel signal is adjusted.
[0004]
A metal halide lamp that can obtain a large amount of light is preferably used as the light source lamp. However, the illumination light output from the metal halide lamp has uneven color temperature distribution in the cross section of the light beam, for example, the blue component is strong on the anode side, and the cathode side Then, there is a characteristic that the red component is strong. In order to adjust the amount of light, an aperture is provided between the light source lamp and the light guide, and this aperture reduces the amount of light by gradually closing the optical path from one end, for example. Therefore, when the aperture is changed, the color temperature of the illumination light supplied to the subject is different, and even when the white balance processing as described above is performed, an appropriate white balance may not be obtained.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to keep white balance constant in an electronic endoscope apparatus regardless of the aperture opening degree.
[0006]
[Means for Solving the Problems]
An electronic endoscope apparatus according to the present invention includes a scope having a solid-state imaging device, and a memory that holds correction data for adjusting white balance of a video signal for one frame obtained from the solid-state imaging device, and illumination. A light source that supplies light to the scope, an aperture that adjusts the amount of illumination light, a detection unit that detects the aperture of the aperture, and correction data corresponding to the aperture are read from the memory and obtained from the solid-state imaging device It is most important to include a processor having a white balance adjustment unit that corrects the white balance of a video signal for one frame based on correction data, and a monitor device that reproduces a subject image based on the corrected video signal. Features.
[0007]
In the electronic endoscope apparatus, it is preferable that the correction data stored in the memory can be rewritten.
[0008]
An electronic endoscope system according to the present invention includes a scope having a solid-state imaging device and a memory that holds correction data for adjusting white balance of a video signal for one frame obtained from the solid-state imaging device. , A light source that supplies illumination light to the scope, a diaphragm that adjusts the amount of illumination light, a detector that detects the aperture of the diaphragm, and correction data corresponding to the aperture of the diaphragm are read from the memory and obtained from the solid-state imaging device A processor having a white balance adjustment unit that corrects the white balance of the video signal for one frame based on the correction data, a monitor device that reproduces the subject image based on the corrected video signal, and the corrected video And a recording device capable of recording a signal.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
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 detachably attached to the scope 10. A light guide member 12 made of an optical fiber bundle is inserted into the scope 10 up to the scope distal end portion 10 a, and the proximal end side of the light guide member 12 is a light source provided in the processor 100 when the scope 10 is attached to the processor 100. 102 is optically connected. The light source 102 is, for example, a metal halide lamp.
[0011]
The illumination light from the light source 102 is guided to the scope distal end portion 10a by the light guide member 12, and the front subject, for example, the internal organ officer X is illuminated. A diaphragm 120 that adjusts the amount of illumination light supplied to the light guide member 12 is provided between the light source 102 and the incident end of the light guide member 12.
[0012]
The scope distal end portion 10a is provided with an image sensor 14 formed of a solid-state image sensor, for example, a CCD. The image sensor 14 includes an objective lens system combined with the CCD. In this embodiment, a simultaneous imaging method is adopted to reproduce a color image, and an optical image of a subject illuminated with white illumination light is formed on a light receiving surface of a CCD in which a complementary color filter is formed on-chip by an objective lens system. Be made. The optical subject image formed on the CCD is photoelectrically converted into an analog pixel signal for one frame, and is sequentially read out from the image sensor 14 by the CCD drive circuit 22 built in the connector unit 20 of the scope 10.
[0013]
The analog pixel signal read from the imaging sensor 14 is processed by the primary processing circuit 24 built in the connector unit 20 according to the characteristics of the imaging sensor 14 and the optical characteristics of the scope 10, such as clamping processing and sample hold processing. White balance correction processing, gamma correction processing, contour emphasis processing, amplification processing, and the like are performed, and are output to the video signal processing circuit 104 of the processor 100 as analog video signals in accordance with a predetermined standard, for example, the NTSC standard. In the video signal processing circuit 104, the luminance signal and the color signal are separated from the analog video signal for one frame. The complementary color signals separated by the on-chip complementary color filter on the CCD are converted into R, G, and B three-color digital signals. Each color signal is temporarily stored in the R memory 106, the G memory 108, and the B memory 110, respectively.
[0014]
The horizontal synchronizing signal and the vertical synchronizing signal output from the timing circuit 112 are added to the three-color digital signals for one frame sequentially read from the respective color memories 106, 108 and 110, and sent to the video processing circuit 114. The video processing circuit 114 is provided with a low-pass filter that removes a high-frequency band component that becomes noise from the three-color digital signal. The video processing circuit 114 outputs the three-color digital signal for one frame that has passed through the low-pass filter to the white balance adjustment circuit 130.
[0015]
The three-color digital signal output from the video processing circuit 114 is adjusted in white balance in the white balance adjustment circuit 130 and converted into an analog color video signal such as an NTSC composite video signal, and then recorded on a monitor device 200 or a VCR. It is output to the device 300. Since the white balance correction process in the primary processing circuit 24 assumes the color temperature of the light source 102 to be a predetermined value, if the color temperature of the light source 102 changes according to the opening of the aperture 120, the white balance is not necessarily appropriate. Don't be. For this reason, the white balance is readjusted by the white balance adjusting circuit 130 as will be described later.
[0016]
The aperture of the diaphragm 120 is adjusted by the diaphragm adjustment circuit 122, and thereby the amount of light is adjusted. The aperture adjustment circuit 122 calculates the average luminance level of the digital pixel signal for one frame output from the video signal processing circuit 104, and drives and controls the aperture 120 so that the optimum aperture is obtained based on the average luminance level. To do. As described above, the processor 100 has an automatic light control function for adjusting the amount of illumination light so that the brightness of the subject image becomes an appropriate level.
[0017]
The processor 100 includes a throttle opening degree detection circuit 124 that detects the opening degree of the throttle 102, and data of the detected throttle opening degree is sent to the system control circuit 116. The white balance adjustment circuit 130 obtains aperture opening data from the system control circuit 116 when adjusting the white balance, and outputs correction data corresponding to the aperture opening, specifically the output levels of the R and B signals. The R gain correction coefficient α and the B gain correction coefficient β to be adjusted are read from a nonvolatile memory such as the EEPROM 26 provided in the connector unit 20 of the scope 10, and the gains of the R signal and the B signal are adjusted for each pixel. By this white balance correction processing, the white balance of the subject image on the monitor screen is always adjusted appropriately regardless of the change in aperture opening. Therefore, the doctor who is the operator can accurately diagnose the affected area.
[0018]
Further, the correction data may be a unique value that further considers the optical characteristics of the scope 10 and the characteristics of the imaging sensor 14. Since the scope 10 is composed of high-precision parts, even a slight mechanical error greatly affects the optical characteristics of each scope 10. In the present embodiment, correction data is provided on the scope 10 side, so that when the scope 10 is replaced, it is not necessary to perform white balance adjustment work according to the optical characteristics of each scope 10 on the processor 100 side.
[0019]
Correction data is written in the EEPROM 26 in advance, and this correction data is a table having a plurality of sets of data including an aperture opening γ and an R gain correction coefficient α and a B gain correction coefficient β corresponding to the opening γ. It is. The correction data can be rewritten as necessary, and can be rewritten only when the mode switch 142 on the operation panel 140 is switched from the normal operation mode to the rewrite mode. As a result, the white balance can be changed according to the preference of the operator or when the lamp is replaced. When the correction data is rewritten, the measurement switch 144 on the operation panel 140 instructs the start and end of the aperture opening measurement.
[0020]
The monitor device 200 reproduces the subject image on the screen based on the analog color video signal. As described above, since the white balance is readjusted in accordance with the aperture opening, the monitor device 200 always displays a subject image with good white balance that is not affected by the aperture opening. The recording apparatus 300 records the subject image as a still image or a moving image.
[0021]
A keyboard 400 is connected to the processor 100, and character information such as a patient name and a diagnosis date and time input from the keyboard 400 is converted into a character pattern signal by the system control circuit 116 and output to the video processing circuit 114. Added to the digital signal. Thereby, the character information is displayed on the screen of the monitor device 200 together with the reproduced image of the optical subject image.
[0022]
The system control circuit 116 is a microcomputer that controls the entire operation of the processor 100, and includes a CPU, a ROM that stores programs and parameters for executing various routines, and a RAM that temporarily stores data and the like. The timing circuit 112 outputs clock pulses for synchronizing the circuits 104, 106, 108, 110, 114, and 116.
[0023]
FIG. 2 is a flowchart showing a white balance correction processing routine executed in the system control circuit 116. This routine is started when it is determined from the video processing circuit 114 that a three-color digital signal of a new frame can be output to the white balance adjustment circuit 130.
[0024]
In step S120, the R signal, G signal, and B signal for one frame output from the video processing circuit 114 are stored in a memory (not shown) of the white balance adjustment circuit 130. In step S122, data of the aperture γ measured simultaneously with the imaging timing is read into the white balance adjustment circuit 130. In step S124, the gain correction coefficients α and β corresponding to the read aperture opening γ are read from the EEPROM 26 to the white balance adjustment circuit 130.
[0025]
In the next step S126, the white balance adjustment circuit 130 adjusts the level of the R signal and the B signal. Specifically, when the R signal is read from the memory and D / A converted, the gain is corrected to the R signal. The coefficient α is multiplied, and when the B signal is D / A converted, the B signal is multiplied by the gain correction coefficient β. The G signal is D / A converted without level adjustment. In step S128, an analog color video signal is generated based on the level-adjusted R signal, G signal, and B signal, and is output to the external monitor device 200 and recording device 300 connected to the processor 100. This completes the white balance correction processing routine.
[0026]
Next, a correction data update routine for rewriting correction data will be described with reference to the flowcharts of FIGS. This routine is executed in the system control circuit 130 and is started when the mode switch 140 selects the rewrite mode.
[0027]
When the correction data is rewritten, a reference white envelope 500 is prepared as shown in FIG. 5, and a predetermined reference white is applied to the inner wall surface of the envelope 500. The distal end portion 10a of the scope 10 is inserted into the enclosure 500, and the distal end surface 10b is brought close to the inner bottom surface 502 of the enclosure 500 as shown in FIG.
[0028]
In step S200, it is determined whether measurement start is instructed by the measurement switch 144. Step S200 is repeatedly executed until the start of measurement is instructed. When the measurement switch 144 is pressed and the start of measurement is instructed, step S202 is executed. Here, the initial value 1 is assigned to the parameter n indicating the number of measurements. . In step S204, the throttle opening γn is measured and read from the throttle opening detection circuit 124 to the system control circuit 116. At this time, the levels of the R signal, G signal, and B signal input to the white balance circuit 130 are measured. Values Rn, Gn, and Bn are measured and read out to the system control circuit 116 (step S206). In step S208, it is determined whether or not 10 microseconds have elapsed. If 10 microseconds have elapsed, it is further determined in step S210 whether or not the measurement end is instructed by pressing the measurement switch 144 again. If the measurement switch 144 is not pressed again, the parameter n is incremented by 1 in step S212, and the process returns to step S204. That is, the throttle opening γn and the R signal level Rn, G signal level Gn, and B signal level Bn at that time are detected every 10 microseconds from when the measurement switch 144 is pressed once until it is pressed again.
[0029]
During the execution of steps S202 to S212, the endoscope distal end portion 10a is gradually pulled out in the direction of arrow Y from the state shown in FIG. 5A by the operator, and as shown in FIG. The distal end surface 10b is separated from the front end. Since the amount of reflected light decreases as it moves away from the inner bottom surface 502, the aperture is gradually increased by the automatic elevation function. Accordingly, R, G, and B signal levels corresponding to various throttle openings are obtained.
[0030]
If it is determined in step S210 that the end of measurement has been instructed, the number of times of measurement n is substituted into parameter N in step S214. , R signal level R (n), G signal level G (n), and B signal level B (n)) are stored in a RAM (not shown) of the system control circuit 116.
[0031]
Next, in step S220, the parameter n is returned to the initial value 1 again, and the throttle opening γn measured in step S222 and the corresponding RGB signal levels Rn, Gn, and Bn are read out. In step S224, an R gain correction coefficient αn is determined such that the ratio between the G signal level Gn and the R signal level Rn after the white balance correction process is 1: 1. The R gain correction coefficient αn is determined by changing the value with a predetermined increment Δα between 0.7 and 1.3, for example, with an initial value of 1, and the product of the input R signal level Rn and αn at that time is It is obtained by a method of selecting a value that matches the input G signal level Gn. Subsequently, in step S226, a B gain correction coefficient βn is determined such that the product of the input G signal level Gn and the input B signal level Bn and βn is 1: 1. The determination of the B gain correction coefficient βn is the same as in step S224, and a description thereof is omitted.
[0032]
In the next step S228, it is determined whether or not the parameter n is equal to or greater than the number of measurements N. If n is smaller than the number of measurements N, n is incremented by 1 in step S230 and the process returns to step S222. That is, steps S22 to S226 are repeated N times to obtain an R gain correction coefficient αn and a B gain correction coefficient βn respectively corresponding to N throttle openings γn (n = 1 to N).
[0033]
If it is determined in step S228 that the parameter n is equal to or greater than the number of measurements N, that is, N throttle openings γn, R gain correction coefficient αn, and B gain correction coefficient βn are obtained, these are corrected in the EEPROM 26 in step S232. And written as data. At this time, if correction data already exists in the EEPROM 26, the data is overwritten. When step S232 ends, the correction data update routine ends.
[0034]
As described above, in the electronic endoscope system according to the present embodiment, the white balance adjustment circuit 130 that adjusts the white balance according to the aperture opening is provided, so the color temperature of the light source 102 according to the aperture opening. The white balance can be kept constant even when the change occurs, and a subject image with extremely good white balance can be reproduced in the monitor device 200. Therefore, it is useful for early detection of the affected area, and there are advantages such as shortening the examination time and reducing the burden on the patient. In addition, when white balance correction data that takes into account the characteristics specific to the scope is used, the correction data is stored in the EEPROM 26 of the scope 10, and even if the scope 10 is replaced, it is not necessary to readjust for that purpose. . The correction data in the EEPROM 26 can be freely rewritten, and a white balance can be set according to the preference of the operator.
[0035]
【The invention's effect】
As described above, the electronic endoscope apparatus of the present invention can always reproduce an appropriate color regardless of the aperture opening.
[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 a white balance correction processing routine.
FIG. 3 is a flowchart showing the first half of a correction data update routine.
FIG. 4 is a flowchart showing the latter half of the correction data update routine.
FIG. 5 is a perspective view showing an enclosure used at the time of rewriting correction data together with a distal end portion of an endoscope.
[Explanation of symbols]
10 Scope 14 Image sensor 26 EEPROM
100 processor 130 white balance adjustment circuit 200 monitor device

Claims (2)

A scope having a solid-state imaging device, and a memory for holding rewritable correction data for adjusting the white balance of a video signal for one frame obtained from the solid-state imaging device to be constant;
A light source that supplies illumination light to the scope, an aperture that adjusts the amount of illumination light, a detection unit that detects the aperture of the aperture, and correction data corresponding to the aperture of the aperture are read from the memory and A processor having a white balance adjustment unit that corrects a white balance of the video signal for one frame obtained from a solid-state image sensor based on the correction data;
A monitor device that reproduces a subject image based on the corrected video signal ,
The electronic endoscope apparatus , wherein the correction data corresponding to the aperture opening is a table having a plurality of sets of data including the aperture opening and a correction coefficient corresponding to the aperture opening . A scope having a solid-state imaging device, and a memory for holding rewritable correction data for adjusting the white balance of a video signal for one frame obtained from the solid-state imaging device to be constant;
A light source that supplies illumination light to the scope, an aperture that adjusts the amount of illumination light, a detection unit that detects the aperture of the aperture, and correction data corresponding to the aperture of the aperture are read from the memory and A processor having a white balance adjustment unit that corrects a white balance of the video signal for one frame obtained from a solid-state image sensor based on the correction data;
A monitor device for reproducing a subject image based on the corrected video signal;
A recording device capable of recording the corrected video signal ,
The electronic endoscope system according to claim 1, wherein the correction data corresponding to the aperture opening is a table having a plurality of sets of data including the aperture opening and a correction coefficient corresponding to the aperture opening .

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