JPH03191941A - Device for controlling quantity of light of light source for electronic endoscopic apparatus - Google Patents

Abstract

PURPOSE:To accurately control quantity of light even when the title device is inserted in color temp. environment different from that in a white box after a quantity-of-light control reference level is controlled in the white box by setting the synthetic sensitivity ratio of R, G, B including an illumination system and an imaging system to SR:SG:SB and operating and controlling a quantity-of- light iris mechanism in the almost reciprocal ratio of 1/SR:1/SG:1/SB. CONSTITUTION:The synthetic sensitivity ratio SR:SC:SB of R, G, B is calculated and the mixing ratio of P, G, B in the image signal used in the control of quantity of light is set LR:LG:LB sc as to form a formula LR:LG:LB 1/SR:1/ SG:1/SB. As a result, a reference signal level LC for controlling throttling quantity so as to make the level of the image signal constant by inputting a control signal to a throttling drive mechanism 31 becomes LC LR+LG+LB=K(1/SR +1/SG+1/SB). Since 1/SR+1/SG+1/SB is preset, a throttling controller 32 is operated so that an image is displayed on a monitor screen at a proper brightness level to set the mu-factor K of the output image signal of a CCD 1 inputted to an ALC 30. By this method, the reference signal level LC is obtained and the effect of color can be excluded.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD 1 The present invention relates to a light source light amount adjustment method for an electronic endoscope device for controlling the aperture amount in a light source light amount aperture mechanism in the electronic endoscope device. [Prior art 1] An electronic endoscope device includes an electronic endoscope that has a built-in solid-state image sensor at the tip of the insertion section, and R and G signals obtained from the solid-state image sensor.
, B, and a display device that displays an image of the observation target area using the color image signals output from the processor. However, since the endoscope is inserted into a dark place such as inside the human body, it is necessary to illuminate the area to be observed. For this purpose, a light source section is provided, and the illumination light from this light source section is emitted from the distal end of the insertion section via a light guide. Here, when driving the solid-state image sensor in a frame sequential manner,
In some cases, the drive is performed simultaneously. In the case of the field sequential method, a rotating color filter disk is interposed in the optical path of the illumination light from the light source, and by rotating the color filter disk, R, G, and B are driven. Each wavelength of light is selected and irradiated sequentially. In addition, in the case of a simultaneous type, R, G,
Since a filter for selecting the wavelength of B is provided, the light source section provides direct illumination with white light. Here, whether sequential R, G, and B illumination is performed or white illumination is performed, it is necessary to adjust the amount of illumination light depending on the region to be observed. In other words, when observing a position far from the tip of the insertion tube, the amount of light reflected from the area to be observed decreases and the image displayed on the monitor screen becomes dark, so the amount of light from the light source must be increased. . Additionally, if the site to be observed is close to the tip of the insertion tube, the amount of reflected light will be large.
In order to prevent the solid-state image sensor from becoming saturated, it is necessary to reduce the amount of light from the light source to some extent. For this purpose, a light amount diaphragm member is inserted in the middle of the optical path from the light source lamp to the light guide, and by adjusting the amount of light from the light source according to the area to be observed, the amount of light received by the solid-state image sensor becomes almost constant. It is controlled as follows. For example, when obtaining a video signal by sequential illumination, R, G, and G signals input from a solid-state image sensor to a processor
, B, the brightness information is extracted from the output video signal of this solid-state image sensor, and a light amount signal based on this brightness level signal is sent to an automatic light amount control device (A).
LC), and if the image level is higher than a predetermined reference value, the light amount diaphragm member is driven to make the diaphragm aperture smaller to reduce the illumination light amount, and if it is lower than the reference value, The light quantity diaphragm member is controlled to open the diaphragm. Here, in ALC, a reference signal is used to control the amount of light based on the sum of the video levels of each R, G, and B video signal, and this reference signal and the video level of the video signal actually output from the solid-state image sensor are used. I am trying to compare. However, in the color filter disk, the transmittance of each RlG and H wavelength light is not constant, and there are differences in the sensitivity characteristics of the solid-state image sensor, so the video signals of each color of R, G, and B are different. The image level is not constant. Therefore, when setting the reference value, it is necessary to give a constant mixing ratio to each of these R, G, and B video signals, and for this reason, in the conventional technology, the reference value for light amount control is The signal level is set to LC = k (αR + βG + γB) (where k is the amplification setting value in the aperture adjuster), and this reference signal is used to adjust the output video signal from the solid-state image sensor during actual shooting. Negative feedback was applied to the output signal, and the light aperture member was controlled based on the output signal. The values of β and γ mentioned above are determined empirically. For example, when β is set to 1.5, γ is set to 2,
Or β is 2. γ was set to 3. A desired video output level can be obtained by presetting the reference value of the aperture by operating the aperture adjuster, which is inevitably performed when taking white balance inside the white box. [Problems to be Solved by the Invention] By the way, as mentioned above, when the aperture adjuster is adjusted in the white box and the device is actually inserted into the body cavity,
When capturing an image using a solid-state image sensor, it is not always possible to obtain a constant video output level, which may cause problems such as the monitor screen being too dark or too bright. The inventor of the present invention investigated the causes of variations in video output levels as described above, and was able to complete the present invention by obtaining the knowledge shown below. That is, for example, when setting R:G:B=1:2:3, the signal level LC that is the reference for controlling the light amount in the white box is such that the video signal ratios of RlG and B are all equal. It is set so that For this reason, R
= G = , B = L, and as a result, LC = k
(R+2G+3B)=6kL. However, inside the body cavity, the inner walls of internal organs exhibit a red color, so the R of the illumination system inside the white box is
, G, B output signal level ratio and R, G in the body cavity
, B, and in the body cavity, red is most emphasized, green is reduced, and blue is almost negligible; therefore, LC=k (
R+2G). Here, since R=L>G, the light amount control reference signal L(:=k (L+2G)<3kL. As a result, the value becomes even smaller than 6kL adjusted with the white box, so this white In order to ensure the red level adjusted inside the box, the light aperture mechanism will be controlled too close to open, making it impossible to accurately adjust the light amount.For this reason, the light amount control standard will be After adjusting the level, in order to maintain the same signal level LC inside the body cavity etc. into which it is actually inserted, the aperture adjuster must be operated again to reset the reference value. Therefore, the present invention has been made in view of the above points, and its purpose is to adjust the amount of light within the white box. To provide a light source light intensity adjustment method for an electronic endoscope device that can accurately adjust the light intensity even if the white box is inserted into a color temperature environment different from that of the white box after adjusting the control reference level. [Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention takes out the light amount control signal LC=αR+βG+γB behind the white balance means, and controls the R, including the illumination system and the imaging system. G.
When the overall sensitivity ratio of B is SR:SG:SR, HaboK (1/SR+1/SG+1/SB) (However,
The feature is that the operation of the light amount diaphragm mechanism is controlled by using the value (K is the amplification degree setting value) as the light amount control reference level. [Effect 1] As mentioned above, when setting the light amount control reference level,
Without using the R, G, and B output signals themselves as elements,
The actual R, G, B
K (1/SR+1
/SG+1/SB) as a reference value for controlling the amount of light, it becomes possible to eliminate the influence of color temperature. Therefore, if you set a reference level for controlling the light amount when adjusting the light amount that is normally performed to maintain white balance in a white box, it is possible to use it in a special color temperature environment such as inside a body cavity. However, there is no need to readjust this reference value. Furthermore, even if the white balance is adjusted again under such an environment, there is no need to readjust the aperture adjustment.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. First, FIG. 1 shows a schematic configuration of an imaging system in an endoscope apparatus. In the figure, 1 is a COD as a solid-state image sensor, 10 is an illumination means, and 20 is a processor that processes a video signal. The CCDI is provided at the tip of the insertion section of the endoscope together with a lens 12 attached to the output end 11a of a light guide 11 that transmits illumination light. Therefore, under illumination by the illumination light from this light guide 11, an image of the observation target part can be captured by CCDI. The illumination means 1° has a light source lamp 13, and the illumination light from the light source lamp 13 is transmitted through a light amount diaphragm member 14. The light enters the incident end 11b of the light guide 11 via the condensing lens 15 and the color filter disk 16. The processor 20 outputs R2O,B from the CCDI.
The video signal processing circuit 21 processes CCD output video signals of each color, and the R, G, and B video signals processed by the video signal processing circuit 21 are converted into digital signals by an A/D converter 22. Converted and field memory 2
It is stored in 3. When a video signal for one field is input to the field memory 23, the R, G, and B signals are simultaneously read out and sent through the D/A converters 24R, 24G, and 24B. The signal is converted into an analog signal, mixed by an encoder 25, and a color video signal is output. As already explained, when photographing inside a body cavity, etc., there are cases in which images are taken of a region close to the tip of the insertion section of the endoscope, and cases in which images are taken of a region far from the tip of the insertion tube. In this case, the amount of illumination light that enters the incident end 11b of the light guide 11 from the light source lamp 13 must be changed. For this purpose, the light amount diaphragm member 14 is made into a variable diaphragm, and the amount of aperture by the light amount diaphragm member 14 is changed in accordance with the change in the brightness level of the output video signal from the CCDI. Therefore, in order to drive the light amount diaphragm member 14. An ALC30 is provided. This ALC30
has an aperture drive mechanism 31 equipped with a servo mechanism for driving the light amount aperture member 14, and operates the aperture based on the R, G, and B CCD output video signals input from the CGDI to the video signal processing circuit 21. A drive signal for the drive mechanism 31 is obtained. For this purpose, it is necessary to set a light amount control reference level to be compared with the CCD output video signal.
For example, when the amount of illumination light emitted from the light source lamp 13 is constant, there is a difference in the transmittance of the color filter disk 16 for light in the R, G, and B wavelength ranges. Further, depending on the structure of the light amount diaphragm member 14, the amount of light of each wavelength of R, G, and B may not be constant. moreover,
The sensitivity of the CCD 1 is not uniform depending on the R, G, and B wavelength light. For this reason, it is necessary to adjust the reference signal level by giving a certain ratio to the level of the light amount control reference signal. Thus, R, G, and R obtained from the video signal processing circuit 21
If the reference level is set by taking in the CCD output video signals of each color of B as they are, the target output level will not be selected under a special color temperature. Therefore, in the present invention, when white balancing the color video signal output from the processor 20 in the white box, after presetting a predetermined reference level by adjusting the light amount level with the aperture adjuster 32, Even when photographing is performed under a special color temperature environment, the light amount control reference signal level can be set so that there is no need to readjust the reference level value. Here, first, the overall sensitivity ratio of R, G, and B on the illumination means 10 side and the CCD 1 is determined. Here, the overall sensitivity ratio is the sensitivity ratio of the color filter disk 16 to each wavelength of R2O and B, the transmittance of each wavelength of the light guide, and the attenuation rate of each wavelength of R, G, and B when passing through the light aperture member 14. If they are different, it is the sensitivity ratio of the entire illumination system and imaging system including this attenuation ratio and the sensitivity ratio of CC; Di as a solid-state imaging device to R, G, and B. This overall sensitivity ratio can be calculated from the design values of each member constituting the illumination system and the imaging system, and can also be determined from actually measured values. In this way R,G. Find the overall sensitivity ratio SR:SG:SR of B, and calculate the mixing ratio of R, G, and B in the video signal used for light amount control as LR:
When LG: LB, SRx LR: S
Set the values of LH, LG, and LB so that Gx LG:5BxLBMisaki1:1:l. That is,
LR: LG: LB# 1/SR: 1/SG: 1
/SB. As a result, a reference signal level LC is inputted to the aperture drive mechanism 31 to control the aperture amount so that the level of the video signal is constant.
As, LG Aya LR+ LG+LB'':K (1/S
R+1/SG+1/SB) (where K is the amplification setting value preset by the aperture adjuster 32). In this way, the RGB ratio setting means 33 is provided to compare the reference signal level LC with the video signal actually output from the CCD 1 and input a control signal to the aperture drive mechanism 31. This RGB ratio setting means 33 is configured as shown in FIG. 2, for example. Therefore, the RGB ratio setting means 33 divides the resistor R2, R2, R
3 each have a switch SL. S2. S3 is connected, and this switch Sl, S2.
S3 is turned on and off based on the enable signals of R2O and B.
These resistors R
1° R2, R3 gives the ratio of SR, SG, SH, ie l/SR. The resistance value is set to obtain 1/SG and 1/SB. Further, an aperture setter 3Z is connected to the amplification means 36, and the amplification degree K of this amplification means 36 is set. In addition, here, the resistance values of resistors R1, R2, and R3 can be set by calculating the overall sensitivity ratios SR, SG, and SB of R2O and H from the design values of the illumination system and the imaging system. By taking a picture inside the white box, you can set it after actually measuring it. If the latter method is used, resistors R1, R2,
R3 may be a variable resistor. Therefore, a reference level LC for light amount control is obtained by the amplification degree by the amplification means 36 and 1/SR+L/SG+l/SR in the RGB ratio setting means 33, and this reference signal provides the R, By applying negative feedback to the G and H output video signals, the difference between this reference signal and the CCD output video signal is calculated, and the difference is amplified by the amplifier 34 and detected by the detection circuit 35.
The control signal level for the amount of light from the light source can be obtained. By inputting this control signal to the aperture drive mechanism 31, the aperture amount of the light amount aperture member 14 can be changed. Therefore, the RGB ratio setting means 33 of the control signal output circuit 33
Since l/SR+ 1/SG+ 1/SB is set in advance by a, R at CCDI is set in the white box.
, G, and B, operate the aperture adjuster 32 so that the image is displayed on the monitor screen at an appropriate brightness level.
A reference signal level LC can be obtained by setting the amplification degree K of the output video signal of the CCD 1 that is input to the CCD 1. In this way, the reference signal level L for controlling the amount of light from the light source is
Since C is set based on the amplification setting value and the overall sensitivity ratios SR, SG, and SB, the influence of color temperature can be eliminated, and adjustments can be made in the -degree box. After that, there is no need to readjust the control image level by controlling the light amount diaphragm member 14 according to the object to be inserted into the insertion section of the endoscope. As shown in FIG. 3, the processor includes a D/A converter 24R, in addition to the video signal processing circuit 21'.
Video signal processing circuit 114 on the output side of 24G and 24B
In the case of a configuration in which 0 is provided, the RGB ratio setting means 33
' may be connected to this video signal processing circuit [40]. Moreover, the same light amount control can be performed not only when sequential illumination is performed, but also when white illumination is performed. In this case, since no color filter disk is used, the control may be performed based on the R, G, and H sensitivity ratios of the solid-state imaging device and the four filters attached to the solid-state imaging device. Effect 1 As explained above, the present invention has the following advantages: When the overall sensitivity ratio of each color video signal of RlG and B to the light source light amount of the illumination light irradiated toward the observation target part (SR:SG:S), The light intensity diaphragm mechanism reduces the maximum likelihood of the light source light K (1/SR+
Since the light source light intensity was set to be controlled based on the control standard Shinshichi, which is 1/SG + 1/SR), in order to maintain white balance, I adjusted the aperture within the white box, which is normally used. Later, there is no need to readjust the V when taking pictures in a special color temperature environment such as inside a body cavity. However, there is no particular problem.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention. FIG. 1 is an explanatory diagram showing the overall configuration of an electronic endoscope imaging system, and FIG. 2 is a configuration of a control signal output circuit. Explanatory diagram, 3rd
The figure is an explanatory diagram of the overall configuration of an electronic endoscope imaging system showing a second embodiment of the present invention. 1: solid-state image sensor, 10: illumination means, 11 light guide, 13: light source lamp, 14: light amount diaphragm member, 16:
Color filter disk, 20: Processor, 21: Video signal processing circuit, 30: ALC131: Aperture driving means, 3
2: Aperture adjuster, 33: Control signal output circuit, 33, 33
': RGB ratio setting means, 34: amplifier, 35: detection circuit, 21': video signal processing circuit 1, 40 ni video signal processing circuit ■. Diagram

Claims (1)

[Claims] An electronic endoscope with a built-in solid-state image sensor at the tip of the insertion tube,
An electronic endoscope comprising a processor that processes video signals of each color of R, G, and B obtained from the solid-state image sensor, and a display device that displays an image of the observation target using the color video signal output from the processor. In the mirror device, when the light amount control signal is extracted after the white balance means and the overall sensitivity ratio of R, G, and B including the illumination system and imaging system is SR:SG:SB, the reciprocal ratio is approximately 1. /S
A light source light amount adjustment method for an electronic endoscope device, characterized in that the operation of a light amount diaphragm mechanism is controlled at a ratio of R:1/SG:1/SB.