JP2005033282A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device capable of keeping the color balance constant at all times even when an illumination luminous quantity is controlled. <P>SOLUTION: The imaging device is provided with a scope information storage element 15 for storing information of a CCD 12 or the like built in a scope 2, an electronic shutter control circuit 43 receives the information as information for determining an electronic shutter speed, further the electronic shutter control circuit 43 receives information about a correction coefficient of an electronic shutter read from an electronic shutter speed correcting purpose memory 26 on the basis of information about the position of an aperture 24 being a determinant of a light emission characteristic and the illumination luminous quantity of a lamp 21 of a light source unit 3, and the electronic shutter control circuit 43 is characterized in to keep the color balance constant at all times even when the illumination luminous quantity is subjected to variable control by using the electronic shutter to control a charge storage time of the CCD 12 through the use of each of the information items of the side of the scope 2 and the side of the light source unit 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial application fields]
The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus suitable for using frame sequential light as illumination light.
[0002]
[Prior art]
In recent years, endoscope apparatuses that irradiate illumination light and obtain an endoscopic image in a body cavity have been widely used. In this type of endoscope apparatus, the illumination light from the light source means is guided into the body cavity using a light guide or the like to irradiate the subject, and the return light is sent to the electronic endoscope using the solid-state imaging device. By imaging the image and processing the signal with a processor, the endoscopic image can be displayed on the observation monitor and the living tissue can be observed.
[0003]
In particular, in the case of a field sequential endoscope apparatus, white light in the visible light region (hereinafter referred to as normal light) emitted from a light source means is converted into a plurality of colors as a surface sequential light through a rotation filter such as RGB. A color image is obtained by separating and irradiating the subject, and image processing based on the image signal based on the return light by the processor.
[0004]
The brightness adjustment of the image signal is performed by at least one of an illumination light diaphragm, an electronic shutter, and an amplification circuit of the processor device. When the captured image is too bright, the amount of light incident on the imaging surface of the solid-state imaging device Therefore, the illumination light diaphragm provided in the light source means operates to limit the amount of illumination light. If the amount of light is still excessive, the charge accumulation time of the solid-state image sensor is shortened by the electronic shutter. However, a method of adjusting the brightness of the image is employed.
[0005]
FIG. 20 is an explanatory diagram of an electronic shutter.
FIG. 20A shows the exposure and light shielding period by the surface sequential rotation filter. When the electronic shutter control is not performed, the exposure period becomes the charge accumulation time T as shown in FIG. The light intensity varies depending on the illumination light aperture position.
[0006]
On the other hand, when the electronic shutter control is performed, it is as shown in FIG. Since the charge accumulation time is controlled by the electronic shutter, the area S of the shaded portion in FIG. 20B is x times (0 <x <1), that is, the electronic shutter is set so that the charge accumulation time is x times. By controlling the amount of illumination that contributes to imaging, that is, the brightness of the image signal can be increased by a factor of x, as indicated by the vertical line in FIG.
[0007]
[Problems to be solved by the invention]
However, the rotary filter for producing the surface sequential light is arranged perpendicular to the luminous flux having a certain thickness, and is driven to rotate alternately between the exposure period and the light shielding period. However, in the case of shifting from the light shielding period to the exposure period, and in the case of shifting from the exposure period to the light shielding period, the luminous flux of the illumination light exists over both the exposure period and the light shielding period. The intensity of fluctuates with time.
[0008]
Specifically, as shown in FIG. 21A, when the light shielding and exposure period are shown at the center position of the luminous flux of the illumination light in the surface sequential rotation filter, the actual illumination light intensity in the exposure period is shown in FIG. As shown in FIG.
[0009]
In other words, the total luminous flux is shielded during the light shielding period, but in the transition period Ka from the light shielding period to the exposure period, the ratio of the total luminous flux existing in the exposure period increases with time, and thereafter the illumination light intensity gradually increases. To increase.
In the period Kb in which the total luminous flux enters the exposure period, the illumination light intensity remains constant.
[0010]
Thereafter, when the transition period Kc from the exposure period to the light shielding period starts, the ratio of the total luminous flux existing in the exposure period decreases with time, so that the illumination light intensity gradually decreases, and finally the total luminous flux Is shielded from light.
[0011]
If the rotary filter is a filter that generates three sequential colors of RGB, the above-described exposure is performed for each color. The amount of illumination light in the exposure period is an integral value of the illumination light intensity from when a part of the light beam enters the exposure period until all of the light beam is shielded, and thus has a trapezoidal shape indicated by the hatched portion in FIG. It is represented by the area of the approximate figure (hereinafter, trapezoidal part).
[0012]
In this case, when adjusting the brightness using the electronic shutter, the electronic shutter is used in order to make the amount of illumination light (used for taking out as a signal charge) x times (0 <x <1) (total illumination light amount). In the method of simply multiplying the charge accumulation time by x, the area of the hatched portion shown in FIG. 21C does not become x times, so the amount of illumination light does not become x times.
[0013]
Therefore, when the charge accumulation time is uniformly controlled to x times with the electronic shutter for each color of RGB, the height (illumination light intensity) in the period Kb and the illumination light in the periods Ka and Kc in FIG. Since the intensity gradient differs for each color, the amount of illumination light is not uniformly x times, and if the electronic shutter speed varies, the illumination light amount ratio of each color varies, and as a result, the color balance of the captured image also varies. There was a problem.
[0014]
Further, the size of the luminous flux of the illumination light varies depending on the position of the illumination light stop provided in the light source device. Accordingly, the inclination of the illumination light intensity in the periods Ka and Kc in FIG. 21B and the height (illumination light intensity) in the period Kb also vary. Therefore, the area of the trapezoidal portion and the shape of the trapezoidal portion also vary.
[0015]
However, since the charge accumulation time control with the electronic shutter in the prior art does not correspond to the area variation and shape variation of the trapezoidal part due to the position variation of the illumination light diaphragm, the illumination light quantity ratio of the surface sequential light varies. However, there is a problem that the color balance of the captured image cannot be kept constant.
[0016]
Also, the illumination light diaphragm is inserted into the optical path having a shape as shown in FIG. 22 to limit the thickness of the light beam, so that the cross section of the light beam of the illumination light that has passed through the illumination light diaphragm is not circular. In addition, the area and shape of the trapezoidal portion also fluctuate, and there is a problem that the illumination light quantity ratio cannot be kept constant.
[0017]
In addition, endoscopes of various specifications exist depending on the site used (upper digestive tract, lower digestive tract, bronchi, etc.). The number and length of the light guides for guiding the illumination light differ depending on the type of endoscope. However, since the light guide has wavelength dependency on the transmission characteristics, the incident light to the light guide and the light guide The illumination light quantity ratio of each color of the surface sequential light is different from the light emitted from the guide.
[0018]
Also, the amount of illumination light depends on the number and length of the light guides, so even if the illumination light amount ratio of the incident light to the light guide is always constant, depending on the endoscope type, The ratio of the quantity of emitted illumination light is different. For this reason, there is a problem in that the illumination light quantity ratio of the emitted light from the distal end portion of the endoscope is different depending on the type of the endoscope, and the color balance of the image captured by the solid-state imaging device is different.
There is also a problem that the color balance of the captured image is different due to two factors such as the variation in the thickness of the light beam depending on the illumination light stop position and the type of endoscope.
[0019]
In addition, the rotational filter used in the light source means, the optical filter of the filter turret, the position control accuracy of the illumination light stop, the objective optical system of the endoscope, the optical filter, the degree of irregularity of the light guide end face, the solid-state image sensor, etc. Since there are individual differences, the color balance of the captured image differs depending on the combination of devices used.
[0020]
Further, in an endoscope apparatus using a high-sensitivity image sensor having a charge multiplication mechanism inside the element as a solid-state image sensor, the amplification factor of the high-sensitivity image sensor is an exponential function as the voltage applied to the element increases. However, in a region where the amplification factor is large, there is a tendency to show a non-linear change outside the exponential function approximation.
[0021]
Therefore, although the amplification factor differs among a plurality of colors of the surface sequential light, the amplification factor ratio is kept constant based on the exponential function, that is, in the internal mirror device that keeps the color balance constant, the amplification factor is small. In the region, the set amplification factor ratio can be maintained. On the other hand, in the region where the amplification factor is large, there is a problem that the color balance fluctuates because it tends to deviate from the set amplification factor ratio.
[0022]
(Object of invention)
The present invention has been made in view of the above circumstances, and in an imaging apparatus constituting a frame sequential endoscope apparatus or the like, even when the amount of illumination light is controlled, the color balance can always be kept constant. It is an object of the present invention to provide an imaging device that can be used.
It is another object of the present invention to provide an image pickup apparatus that can maintain a constant color balance even when a solid-state image pickup device having a charge multiplication mechanism is used inside the device.
[0023]
[Means for Solving the Problems]
In an imaging device that images a subject with a solid-state imaging device based on illumination light emitted from a light source,
Input means for inputting a correction coefficient specific to the light source relating to the amount of illumination light emitted;
Electronic shutter means for controlling the charge accumulation time of the solid-state imaging device based on the input correction coefficient;
Thus, even when the light source is different or the illumination light quantity by the light source is controlled, a unique correction coefficient is used so that a captured image can be obtained while keeping the color balance constant.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIGS. 1 to 6 relate to a first embodiment of the present invention, FIG. 1 shows an overall configuration of an endoscope apparatus including the first embodiment, and FIG. 2 shows a configuration of a rotary filter plate. 3 shows the transmission characteristics of the RGB filter attached to the rotary filter, FIG. 4 shows the relationship between the illumination light aperture and the illumination light intensity, FIG. 5 shows the configuration of the color balance correction circuit, and FIG. 6 shows the electronic shutter. FIG.
[0025]
The purpose of the present embodiment is to control the amount of illumination light to a desired value using an electronic shutter, so that the color balance of the captured image is always kept constant regardless of the type of scope and the individual variation of the scope and light source device. An object is to provide an apparatus and an endoscope apparatus.
[0026]
First, the configuration of the present embodiment will be described.
As shown in FIG. 1, an endoscope apparatus 1 having a first embodiment of the present invention is an electronic endoscope (hereinafter abbreviated as a scope) 2 that is inserted into a body cavity and images the inside of the body cavity. And a light source device 3 that generates illumination light for observation, a processor 4 that performs signal processing on an image signal captured by the scope 2, and an observation monitor 5 that displays an endoscopic image.
[0027]
The scope 2 includes an elongated insertion portion 6 that is inserted into a body cavity, and an operation portion 7 that is provided at the rear end of the insertion portion 6. A light guide 8 that transmits illumination light is inserted into the insertion portion 6, and a light guide connector 9 at the rear end of the light guide 8 is detachably connected to the light source device 3. Light is transmitted, and the subject 10 side such as an affected part in the body cavity is illuminated from the distal end surface attached to the illumination window at the distal end of the insertion portion 6 through an illumination lens.
[0028]
At the tip, an observation window is provided adjacent to the illumination window, and an objective optical system 11 is attached to the observation window, and forms an optical image of the subject 10 illuminated at the imaging position. . For example, a CCD 12 is disposed as a solid-state image sensor at this image formation position, and photoelectrically converts the formed optical image.
An optical filter 13 such as an infrared cut filter is disposed between the objective optical system 11 and the CCD 12.
[0029]
The CCD 12 is electrically connected to the processor 4 through a signal line inserted into the insertion portion 6 or the like. Further, a scope information storage element 15 in which model information of the scope 2, electronic shutter speed, and the like are stored is provided in the operation unit 7 of the scope 2.
[0030]
The light source device 3 includes a lamp 21 such as a xenon lamp that emits light, a filter turret 23 that is provided on the illumination optical path of the lamp 21 and can switch a plurality of optical filters by driving a motor 22, and restricts the amount of illumination light. An illumination light diaphragm 24 for detecting the position, an aperture position detection sensor 25 for detecting the position, an electronic shutter speed correction coefficient storage memory 26 for outputting a correction coefficient for an electronic shutter speed that differs for each diaphragm position, and illumination light. A rotary filter 27 for making surface sequential light, a moke 28 for rotationally driving the rotary filter 27, and a surface sequential light passing through the rotary filter 27 on the base end face (incident end face) of the light guide 8 of the scope 2 are collected. And a condensing lens 29 that emits light.
[0031]
The rotary filter 27 is configured in a disc shape as shown in FIG. 2, and an R filter 31a, a G filter 31b, and a B filter 31c that transmit light of red, green, and blue wavelengths with the center as a rotation axis are arranged. ing.
[0032]
The spectral characteristics of the filter are as shown in FIG. 3, and the portion of the rotary filter 27 other than where the filters are arranged is composed of a member that blocks light.
[0033]
The processor 4 has a CCD driver 32 that generates a drive signal for driving the CCD 12. The processor 4 also includes a preprocess circuit 33 that performs preprocessing on the imaging signal output from the CCD 12, an A / D conversion circuit 34, a color balance correction circuit 35, a multiplexer 36, and synchronization memories 37a and 37b. , 37c, the image processing circuit 38, and the D / A conversion circuits 39a, 39b, 39c in this order. The processor 4 includes a CPU 41 that performs a control operation, a light control circuit 42 that generates a light control signal that performs light control, and an electronic shutter control circuit 43 that controls the speed of the electronic shutter.
[0034]
In the present embodiment, the scope 2 includes a CCD 12 built in the scope 2, an optical system that forms an image on the CCD 12, and a scope information storage element 15 that stores information unique to the light guide 8. Is input to the electronic shutter control circuit 43 that performs electronic shutter control as information for determining the electronic shutter speed.
[0035]
The light source device 3 includes an electronic shutter speed correction coefficient memory 26 that stores an electronic shutter speed correction coefficient when determining the electronic shutter speed. The electronic shutter speed correction coefficient memory 26 stores the light emission characteristics of the lamp 21. The electronic shutter speed correction coefficient corresponding to the characteristics of the optical filter, etc., and the illumination light quantity (detected by the sensor 25 for detecting the position of the diaphragm 24) is stored, and the electronic shutter speed correction coefficient memory 26 stores the light source device. The electronic shutter speed correction coefficient information suitable for color balance is input to the electronic shutter control circuit 43 in the state of arbitrary illumination light quantity 3.
[0036]
When the unique information is input from the scope 2 side and the light source device 3, the electronic shutter control circuit 43 uses the electronic shutter to color-balance the charge accumulation time for each color sequential light in the CCD 12 via the CCD driver 32. Control so that can be held.
[0037]
Also, the correction coefficient value to be multiplied by the color balance circuit 35 (by the memory rewrite signal of the CPU 41) is selected for the R, G, B signals imaged under the surface sequential color light output from the CCD 12. The endoscope apparatus 1 is provided with an imaging apparatus that controls and generates an image signal so that a constant color balance is always maintained.
[0038]
Next, the operation of this embodiment will be described.
When the power is turned on with the scope 2 connected to the light source device 3 and the processor 4, the model information of the scope 2 and the electronic shutter speed are read from the scope information storage element 15 of the scope 2 to the CPU 41 in the processor 4. It is stored (stored) in a register of the CPU 41, and is set in a state where it can be read and used when needed.
[0039]
Here, the electronic shutter speed read from the scope information storage element 15 refers to the number and length of the light guides 8 mounted on the scope 2, the objective optical system 11 and the optical filter 13, and the solid-state imaging element. In consideration of the fact that the CCD 12 differs depending on the model, and that there are individual differences even in the same model, the color balance of the image signal picked up by the scope 2 is kept constant when the scope 2 is manufactured. It is a value measured and stored in advance.
[0040]
Considering that the transmission characteristics (also referred to as transmittance) of the illumination light of the light guide 8 differ depending on the wavelength band of the illumination light, different electronic shutter speeds are set for the respective colors of the frame sequential light.
On the other hand, in the light source device 3, the illumination light emitted from the lamp 21 passes through the optical filter provided in the filter turret 23, and the illumination light quantity is adjusted by the illumination light diaphragm 24 so as to have an appropriate brightness.
[0041]
The relationship between the illumination light stop 24 and the illumination light intensity is, for example, as shown in FIG. The position of the illumination light diaphragm 24 is always detected by the diaphragm position detection sensor 25, and the detected diaphragm position information is output to the electronic shutter speed correction coefficient storage memory 26 and stored in the electronic shutter speed correction coefficient storage memory 26.
[0042]
In the electronic shutter speed correction coefficient storage memory 26, the components of the light source device 3, such as variations in spectral characteristics of optical filters attached to the filter turret 23 and the rotary filter 27, individual differences in the position control accuracy of the illumination light diaphragm 24, and the like Correction factors that take into account the individual differences involved are measured at the manufacturing stage and stored in advance.
[0043]
Based on the aperture position input from the aperture position detection sensor 25, an electronic shutter speed correction coefficient corresponding to the position of the illumination light diaphragm 24 is read from the electronic shutter speed correction coefficient storage memory 26, and the electronic shutter control circuit of the processor 4 is read. 43 is output.
[0044]
The illumination light that has passed through the illumination light diaphragm 24 is converted into surface-sequential light by a rotary filter 27 that is rotationally driven by a motor 28, and is condensed on the incident end face of the light guide 8 of the scope 2 by a condenser lens 29. And is transmitted by the light guide 8 and irradiated from the front end surface to the subject 10 side.
[0045]
The return light from the subject 10 is imaged on the CCD 12 through the objective optical system 11 and the optical filter 13 of the scope 2 and is photoelectrically converted. Then, by applying a drive signal from the CCD driver 32 of the processor 4, the image pickup signal photoelectrically converted by the CCD 12 is input to the preprocess circuit 33 of the processor 4 as an image signal.
[0046]
The image signal input to the processor 4 is subjected to processing such as CDS (correlated double sampling) in the preprocess circuit 33 to remove reset noise and the like, and an image signal component is extracted.
The signal output from the preprocess circuit 33 is converted from an analog signal to a digital signal by the A / D conversion circuit 34 and input to the color balance correction circuit 35.
[0047]
The color balance correction circuit 35 is sometimes called a white balance circuit. As shown in FIG. 5, the color balance correction circuit 35 selects color balance correction coefficient storage memories 45a, 45b, and 45c, which are nonvolatile memories for storing three color balance correction coefficients, and a color balance correction coefficient. And a multiplier 47.
[0048]
The color balance correction coefficient storage memories 45a, 45b, and 45c correspond to image signals captured with the R filter 31a, G filter 31b, and B filter 31c inserted in the optical path, that is, R, G, and B image signals, respectively. The color balance correction coefficient to be stored is stored.
[0049]
Then, the color balance correction coefficients stored in the color balance correction coefficient storage memories 45a, 45b, and 45c are read out from the CPU 41 by a memory rewrite signal (rewriting to the synchronization memories 37a to 37c). FIG. 5 shows a case where the observation mode identification signal in the second embodiment is also input to the color balance correction coefficient storage memories 45a, 45b, and 45c (in this embodiment, the observation mode identification signal is not used). ).
[0050]
The selector 46 stores the color balance correction coefficient storage memory 45a at the timing when the R filter 31a is inserted in the optical path, and the color balance correction coefficient storage memory 45b at the timing when the G filter 31b is inserted in the optical path. At the timing when 31c is inserted in the optical path, the color balance correction coefficient storage memory 45c is selected.
[0051]
The multiplier 47 multiplies the input input image signal (specifically, R, G, B image signals) by the color balance correction coefficient selected by the selector 46 and outputs the result. The color balance correction coefficient calculated by the CPU 41 is written in advance in each color balance correction coefficient storage memory 45i (i = ac).
[0052]
Image signals output from the color balance correction circuit 35 are subjected to frame sequential signal synchronization by the multiplexer 36 and the synchronization memories 37a, 37b, and 37c.
That is, the R image signal captured under the R illumination light that has passed through the R filter 31a is written into the synchronization memory 37a, and the G image captured under the G illumination light that has passed through the G filter 31a. The signal is written in the synchronization memory 37b, and the B image signal captured under the B illumination light passing through the B filter 31c is written in the synchronization memory 37c. These are read out at the same time and output as R, G, B image signals.
[0053]
The synchronized signal is input to the image processing circuit 38. The image processing circuit 38 performs gamma correction processing, structure enhancement processing, color processing, and the like.
The image signal output from the image processing circuit 38 is converted again into an analog signal by the D / A conversion circuits 39a, 39b, 39c, and the image picked up by the CCD 12 is displayed in color on the observation monitor 5.
[0054]
The outputs of the D / A conversion circuits 39a, 39b, and 39c are encoded by an encoding circuit (not shown) and recorded in a digital filing device (not shown) or recorded by photography using a photography device (not shown).
[0055]
The dimming circuit 42 outputs a dimming signal for adjusting the position of the illumination light diaphragm 24 of the light source device 3 based on the image signal output from the color balance correction circuit 35 so that the image has an appropriate brightness. To do. When the light intensity is insufficient, the dimming signal is operated in a direction to open the illumination light diaphragm 24. Conversely, when the light intensity is excessive, the light adjustment signal is operated in a direction to close the illumination light diaphragm 24. In this way, automatic light adjustment (adjustment) is always made to an appropriate illumination light amount.
[0056]
The electronic shutter control circuit 43 multiplies the electronic shutter speed of the scope 2 stored in the CPU 41 and the electronic shutter speed correction coefficient output from the electronic shutter speed correction coefficient storage memory 26 of the light source device 3 for each color. The corrected electronic shutter speed is derived according to the position of the illumination light diaphragm 24, and the derived corrected electronic shutter speed is transmitted to the CCD driver 32.
[0057]
The CCD driver 32 generates and outputs a drive signal for the CCD 12, and generates and outputs an electronic shutter control pulse based on the input corrected electronic shutter speed.
[0058]
As shown in FIG. 6, the electronic shutter sweeps unnecessary charges accumulated in the CCD 12 at the timing set by the sweep pulse P0 and controls the charge accumulation time of the signal charge read by the read pulse P1. There is also an advantage that the occurrence of color misregistration can be suppressed even when the subject 10 is moving.
[0059]
The drive signal output from the CCD driver 32 and the electronic shutter control pulse always provide a constant color balance regardless of the type of scope 2, the individual variations of the light source device 3 or scope 2, and the position of the illumination light aperture 24. It is possible to realize an imaging apparatus that generates an image signal that the user has.
[0060]
In the present embodiment, the electronic shutter speed is changed according to the aperture position. However, when the electronic shutter is used, the illumination light aperture 24 may be fixed to an open position or a specific position. .
The electronic shutter may be added with a function used for controlling brightness in conjunction with the dimming circuit 42.
[0061]
In addition, the electronic shutter speed is not corrected by the correction coefficient, but a lookup table storing electronic shutter speeds corresponding to all positions of the illumination light diaphragm 24, the amount of change from the reference aperture position, It may be performed based on a lookup table that stores all corresponding electronic shutter speeds.
[0062]
Further, since the capacity stored in the scope information storage element 15 is limited, the scope information storage element 15 stores only the model information of the scope 2 and information such as the electronic shutter speed is stored in the processor 4. The setting value may be stored in a large-capacity memory (not shown) provided in, and the setting value may be read and used based on the model information of the scope 2 at the time of activation.
[0063]
Further, when there is no individual difference in the aperture position control accuracy of the light source device 3 or in the optical filter, the dimming signal output from the dimming circuit 42 is input to the electronic shutter control circuit 34, and the dimming is performed. The electronic shutter speed may be corrected based on the signal.
[0064]
The electronic shutter speed correction coefficient storage memory 26 may be provided in the processor 4 and read out an appropriate correction coefficient based on the aperture position information output from the aperture position detection sensor 25 of the light source device 3.
Further, the individual variation correction of the optical filter provided in the rotary filter 27 of the light source device 3 is not an electronic shutter, but is also performed by adjusting the duty ratio of the lamp driving current for changing the light amount of the lamp 21. Good.
[0065]
The present embodiment has the following effects.
By controlling the amount of illumination light to a desired value using an electronic shutter, the color balance of the captured image can always be kept constant regardless of the type of the scope 2 and the individual variations of the scope 2 and the light source device 3.
[0066]
(Second Embodiment)
Next, a second embodiment of the present invention will be described. The purpose of this embodiment is to use an electronic shutter to determine the amount of illumination light even when the illumination light aperture position is open or fixed close to the open position when observing faint light such as fluorescence observation. It is to provide an imaging apparatus and an endoscope apparatus that can obtain an image with appropriate brightness while keeping the color balance of the captured image constant at all times.
[0067]
First, the configuration of the endoscope apparatus 1B provided with the present embodiment will be described.
Since the second embodiment is similar to the first embodiment, different points will be mainly described.
FIG. 7 is an overall view of an endoscope apparatus 1B provided with the second embodiment.
[0068]
The endoscope apparatus 1B drives a scope 2B that can be inserted into a body cavity and has an imaging means, a light source device 3B that supplies illumination light to a light guide 8 of the scope 2B, and an imaging means of the scope 2B. The processor 4B performs signal processing on the image pickup means, and the observation monitor 5 displays the image picked up by the image pickup means in color.
[0069]
The scope 2B in the present embodiment includes an objective optical system 11b, an optical filter 13b, and a fluorescence observation objective in addition to the objective optical system 11, the optical filter 13, and the normal observation CCD 12 in the scope 2 in the first embodiment. A high sensitivity CCD 12b is provided.
[0070]
In addition, the scope 2B switches and drives the CCD 12 for normal light observation and the high-sensitivity CCD 12b for fluorescence observation, and switches the signals picked up by both the CCDs 12 and 12b to be output to the processor 4B. Relay switch 51b is provided.
Furthermore, the scope 2B is also provided with an observation mode changeover switch 52 for switching between the normal light observation mode and the fluorescence observation mode.
[0071]
Accordingly, the scope 2B includes a light guide 8 that transmits illumination light supplied from the light source device 3B to the distal end surface, objective optical systems 11 and 11b that receive return light from the subject 10 based on the illumination light, and an optical filter 13. 13b, a plurality of relay switches for switching between the CCD 12 for normal light observation, the high-sensitivity CCD 12b for fluorescence observation, the drive signal of the CCD 12 or the high-sensitivity CCD 12b, and the image signal (CCD output signal) after imaging. 51a, 51b, scope 2B model information, individual variation, scope information storage element 15 storing corresponding observation mode information, and the like, and an observation mode switching switch 52 for switching the observation mode by switch operation.
[0072]
The light source device 3B in the present embodiment is provided with a rotary filter 27b provided with filters on the inner and outer peripheral sides instead of the rotary filter 27 in the light source device 3 in the first embodiment, and the rotary filter 27b. Can be moved by the moving motor 53 so that one of the inner and outer filters can be selectively disposed on the optical path.
[0073]
In the light source device 3B, an electronic shutter speed storage element 55 is provided in place of the electronic shutter speed correction coefficient storage memory 26.
More specifically, the light source device 3B includes a lamp 21 such as a xenon lamp that emits light, an illumination optical path of the lamp 21, and a filter turret 23 that can switch a plurality of optical filters by driving a motor 22. An illumination light stop 24 for limiting the amount of light; a sensor 25 for detecting the position of the illumination light stop 24; a rotary filter 27b for making the illumination light a surface sequential light; a motor 28 for rotationally driving the rotary filter 27b; A motor 53 for moving the rotary filter 27b in a direction perpendicular to the optical axis of the illumination light, a condenser lens 29 for condensing the surface sequential light via the rotary filter 27b on the incident end face of the light guide 8 of the scope 2B, And an electronic shutter speed storage element 55 for storing the electronic shutter speed.
[0074]
The rotary filter 27b is formed in a disc shape as shown in FIG. 8 and has a double structure with the center as a rotation axis. The outer periphery of the rotary filter 27b is used for normal light observation. An R filter 31a, a G filter 31b, and a B filter 31c that transmit light having a wavelength of 3 are disposed.
[0075]
On the inner periphery, a G ′ filter 56a that transmits narrowband light of 540 to 560 nm, an excitation filter 56b that transmits excitation light of 395 to 475 nm, and a narrowband light of 600 to 620 nm that are used for fluorescence observation are transmitted. An R ′ filter 56c is arranged.
[0076]
The spectral characteristics of the inner and outer filters are as shown in FIGS. 3 and 9, respectively, and the portions other than where the filters of the rotary filter 27b are arranged are configured by members that block light. ing,
Due to the combination of the filter turret 23 and the rotary filter 27b, the illumination wavelengths at the time of fluorescence observation become excitation wavelengths 395 to 475 nm, or 395 nm to 445 nm, edge reflected light 540 to 560 nm, and red reflected light 600 to 620 nm. The spectral characteristics of the illumination wavelength during normal light observation are the same as those in FIG.
[0077]
The processor 4B includes a high-sensitivity CCD driver 57 and a CCD selector (simply abbreviated as “selector” in FIG. 7) 58 in addition to the first embodiment. During normal light observation, the CPU 4 controls the CCD driver 58 so as to select the fluorescence observation, particularly the high-sensitivity CCD 57, by the CCD selector 58. Further, the CPU 41 outputs an observation mode identification signal in accordance with the observation mode selected by the observation mode changeover switch 52, and the CCD selector 58, the color balance circuit 35, the synchronization memories 37a to 37c, and the image processing are output based on the observation mode identification signal. The circuit 38 and the dimming circuit 42 are controlled.
[0078]
In the present embodiment, imaging (observation) can be performed by normal light observation, fluorescence observation can be selected and fluorescence observation can be performed, and high-sensitivity CCD 12b can be used for observation at weak fluorescence observation. Yes. In addition, at the time of fluorescence observation, a captured image with appropriate brightness can be obtained by an electronic shutter.
[0079]
Next, the operation of this embodiment will be described.
The scope 2B used in the present embodiment corresponds to two observation modes such as normal light observation and fluorescence observation.
[0080]
When the power is turned on while the scope 2B is connected to the light source device 3B and the processor 4B, the endoscope device 1B is activated in the normal light observation mode. Simultaneously with the activation, the information stored in the scope information storage element 15 of the scope 2B is read out. That is, from the scope information storage element 15, the model information of the scope 2B, individual variations, corresponding observation mode information, and the like are read out and stored in the CPU 41 in the processor 4B.
[0081]
In the light source device 3 </ b> B, the illumination light emitted from the lamp 21 passes through the filter turret 23. The filter turret 23 has optical filters having different spectral characteristics for each observation mode, and a motor is used so that the optical filter corresponding to the selected observation mode moves on the optical path of the illumination light according to the observation mode identification signal. 22 is rotationally driven, the motor 22 is stopped at a predetermined position, and the filter turret 23 is fixed.
[0082]
The illumination light that has passed through the optical filter of the filter turret 23 is adjusted to have an appropriate illumination intensity by the illumination light diaphragm 24, and is converted into surface sequential light by a rotary filter 27b that is rotated by a motor 28. The
The motor 28 has a different rotation frequency depending on the observation mode, and is driven at 10 Hz in the fluorescence observation and at 20 Hz in the other observation modes.
[0083]
When the observation mode identification signal indicates fluorescence observation, the light source control circuit (not shown) communicates with each other so that the rotation frequency of the rotary filter 27b is synchronized with 10 Hz. The light source control circuits that do not operate operate while communicating with each other so that the rotational frequency of the rotary filter 27b is synchronized with 20 Hz.
[0084]
The motor 53 is driven so that the inner peripheral side of the rotary filter 27b is on the optical path of the illumination light based on a signal from a light source control circuit (not shown) during fluorescence observation. Based on the signal from the light source control circuit, it is driven so that the outer peripheral side of the rotary filter 27b is on the optical path of the illumination light.
[0085]
In the example of FIG. 7, a rack is attached to the motor 28, and a pinion is attached to the motor 53. By rotating the motor 53, the rotary filter 27b is moved in the vertical direction of FIG. .
[0086]
The illumination light that has passed through the rotary filter 27b is condensed on the incident surface of the light guide 8 of the scope 2B by the condensing lens 29, transmitted by the light guide 8, and irradiated on the subject 10 side from the distal end surface, and the return light is emitted. The image is taken by the CCD 12 or the high sensitivity CCD 12b.
[0087]
When switching the observation mode, a signal instructing switching of the observation mode is generated by pressing an observation mode changeover switch 52 provided in the scope 2B, and input to the CPU 41 in the processor 4B.
[0088]
In the CPU 41, when it is detected that an observation mode switching signal has been input, the observation mode information (normal light observation and fluorescence observation in the present embodiment) corresponding to the scope 2B and the observation mode (normal light immediately before the switching operation) are supported. Observation mode indicating observation mode (fluorescence observation (normal light observation)) after switching based on observation (fluorescence observation)) and priority information (1: normal light observation, 2: fluorescence observation) of the corresponding observation mode An identification signal is output.
[0089]
The observation mode identification signal output from the CPU 41 includes the CCD selector 58, the color balance correction circuit 35, the synchronization memories 37a, 37b, and 37c, the image processing circuit 38, the light control circuit 42, and the electronic shutter control circuit 43 in the processor 4B. It is transmitted to a light source control circuit (not shown), relay switches 51a and 51b in the scope 2B, and an electronic shutter speed storage element 55 of the light source device 3B.
[0090]
The CCD selector 58 determines whether the observation mode after switching is fluorescence observation based on the observation mode identification signal. In the fluorescence observation, autofluorescence from the subject 10 (more specifically, biological tissue) based on the irradiated excitation light is observed. Since the autofluorescence is very weak light, a high-sensitivity CCD 12b is used.
[0091]
For example, as shown in USP 5,337,340, the high-sensitivity CCD 12b is a CCD that can control the amplification factor of a signal in the device by inputting a control pulse from the outside of the device. In the CCD, as shown in FIG. 10, charge multiplication using ionization is possible in a CMD (Charge Multiplexing Device) arranged in the element.
[0092]
In the case of FIG. 10, a light receiving area 58 that accumulates signal charges by receiving light, and two rows of signal charges accumulated in the light receiving area 58 are connected through, for example, odd and even vertical transfer units. A horizontal transfer channel 59, a transfer channel 60 with CMD connected to each of the two horizontal transfer channels 59, and a charge detection unit 61 that detects a signal charge multiplied through the transfer channel 60 with CMD. In addition, a high-sensitivity CCD 12b is formed.
[0093]
In the transfer channel 60 with CMD, the signal charge is doubled by the CMD applied voltage included in the drive signal from the high sensitivity CCD driver 57. Therefore, the amplification factor of the high sensitivity CCD 12b is increased. The information on the high sensitivity CCD amplification factor is sent from the high sensitivity CCD driver 57 to the electronic shutter control circuit 43, and is used when controlling the electronic shutter speed as will be described later.
[0094]
The CMD can be arranged for each pixel and can be amplified for each pixel, or can be arranged for a transfer channel and can be amplified for each transfer line. Recently, a CCD capable of controlling CMD not by a control pulse but by a voltage value has been proposed.
[0095]
In the CCD 12b using the CMD, the amplification is performed internally before the charge is read out from the CCD 12b. Therefore, the influence of the readout noise is less than that in the outside of the CCD 12b, and a high S / N image is obtained. There are benefits. Therefore, it is suitable for imaging weak light such as fluorescence. On the other hand, a normal CCD 12 is used for normal light observation.
[0096]
When the observation mode after switching is fluorescence observation, a signal instructing generation of a drive signal is output to the high-sensitivity CCD driver 57. At the same time, generation of the drive signal is stopped for the CCD driver 32. A signal instructing to do so is output.
[0097]
The generated drive signal is sent to the high sensitivity CCD 12b via the relay switch 51a of the scope 2B and used for driving. The image signal (CCD output signal) of the subject imaged by the high sensitivity CCD 12b is input to the processor 4B via the relay switch 51b. On the other hand, when the observation mode after switching is normal light observation, the CCD driver 32 and the high-sensitivity CCD driver 57 operate in the reverse manner.
The relay switches 51a and 51b may be either mechanical type or electric type.
[0098]
The relationship between the CMD applied voltage value and the amplification factor of the high sensitivity CCD 12b is approximated by an exponential function as shown in FIG. 11, and the amplification factor increases as the CMD application voltage value increases. During fluorescence observation, the CMD applied voltage value included in the drive signal of the high-sensitivity CCD 12b is increased or decreased to increase or decrease the amplification factor of the high-sensitivity CCD 12b, and the brightness of the image signal is kept constant.
[0099]
The image signal input to the processor 4B is input to the multiplexer 36, the light control circuit 42, and the electronic shutter control circuit 43 via the preprocess circuit 33, the A / D conversion circuit 34, and the color balance correction circuit 35. Since the signal processing at the subsequent stage of the multiplexer 36 is the same as that of the first embodiment, it is omitted here.
[0100]
In the case of normal light observation, the dimming circuit 42 uses the image signal output from the color balance correction circuit 35 and the observation mode identification signal output from the CPU 41 so that the image has an appropriate brightness under the selected observation mode. Thus, a dimming signal for adjusting the illumination light diaphragm 24 of the light source device 3B is output.
[0101]
When the light intensity is insufficient, the dimming signal is operated in a direction to open the illumination light diaphragm 24. Conversely, when the light intensity is excessive, the light adjustment signal is operated in a direction to close the illumination light diaphragm 24. On the other hand, in the case of fluorescence observation, in order to increase the intensity of the excitation light and increase the intensity of the autofluorescence that is the return light from the living tissue as much as possible, the illumination light diaphragm 24 is opened or close to the open position. To output a dimming signal for instructing to enter a fixed state.
The electronic shutter control circuit 43 does not operate particularly when the observation mode identification signal indicates normal light observation.
[0102]
On the other hand, when the observation mode identification signal indicates fluorescence observation, as described above, since the illumination light diaphragm 24 is opened or fixed at a position close to the opening, the autofluorescence is weak light, but the subject In the case of close proximity to the image, the return light from the subject becomes excessive, and even when the amplification factor of the high sensitivity CCD 12b is set to the minimum of 1, the image signal may be halated.
Therefore, in this case, an electronic shutter control pulse for shortening the charge accumulation time during the exposure period is generated by the electronic shutter.
[0103]
As described above, the amount of illumination light during the exposure period is represented by the area of the trapezoidal portion in FIG. 21C. Therefore, when the accumulated charge amount of the solid-state imaging device is accumulated during the entire exposure period by the electronic shutter. In the case of FIG. 20, even if the illumination light amount contributing to the accumulation of signal charges (in other words, actually used for imaging) is x times the total illumination light amount (0 <x <1), Unlike the case, even if the charge accumulation time is x times, the amount of illumination light is not x times.
[0104]
As a countermeasure, as shown in FIG. 12C, in advance, for each color of the surface sequential light, the area of the trapezoidal portion, that is, the illumination light quantity (contributing to the signal charge) is multiplied by x with respect to the total illumination light quantity. The electronic shutter speed is measured at the time of manufacturing the light source device 3B, and the electronic shutter speed storage element 55 provided in the light source device 3B stores the three points of color, magnification, and electronic shutter speed in association with each other. .
[0105]
12A shows the light shielding period, the exposure period, and the light shielding period depending on the center position of the luminous flux of the illumination light in the surface sequential rotation filter, and FIG. 12B shows the actual illumination in the exposure period in FIG. The light intensity is shown, and this is approximated by a trapezoid as shown in FIG.
[0106]
In addition, as shown in FIG. 12C, data relating to the timing Tx of the electronic shutter control pulse that makes the illumination light quantity that is x times the total illumination light quantity (contributes to the signal charge) is measured in advance. And ask.
[0107]
For example, in the case of controlling to an electronic shutter of 0.8 times, as shown in FIG. 12 (D), as shown in FIG. By controlling the shutter control pulse to be output and the read pulse P1 to be output at the position of timing T0, the signal charge imaged with the illumination light quantity before the sweep pulse P0 is swept out, and the remaining FIG. ) Signal charges imaged under the illumination light amount indicated by the oblique lines (that is, imaged under an illumination light amount 0.8 times the total illumination light amount) can be obtained as an image signal.
[0108]
The situation of the correction coefficient will be supplementarily described below.
As shown in FIG. 7, the illumination light is emitted to the light guide 8 through the lamp 21, the filter turret 23, the illumination light aperture 24, and the rotary filter 27b. in this case
a. Since the optical filters used in the filter turret 23 and the rotary filter 27b have individual variations in spectral characteristics, even if the emitted light from the lamp 21 is constant, the spectral characteristics of the emitted light are different for each light source device 3B. Variations occur. In the rotary filter 27b, white light is divided into three colors of RGB, so that the ratio of the illumination light amount of each color also varies. Also,
b. The position of the illumination light stop 24 also varies depending on the individual light source device 3B.
[0109]
c. From the above a and b, the emitted light from the lamp 21 varies in the amount of illumination light and the RGB ratio for each individual light source device 3B.
In order to correct these, a case will be specifically described where the position of the illumination light stop 24 is controlled in 10 steps.
[0110]
(1) The amount of light is measured in advance using a measuring device such as a light meter at each stage of the aperture position,
(2) Deriving a correction coefficient for correcting to the target value at each stage,
(3) The correction coefficient is stored in the storage element in the light source device.
[0111]
The results of (1) to (3) are shown in the tables of FIGS. 13 (A) and 13 (B). FIG. 13A shows light quantity values measured by a light meter in the case of two light source devices (abbreviated as light source in FIG. 13 for simplicity) A and B.
[0112]
Based on the measurement result, a correction coefficient is derived for correction to the target value as shown in FIG. 13B and stored in the storage element 55 in each light source device. And
(4) The correction coefficient is transmitted to the electronic shutter control circuit 43 in the processor 4B,
(5) The electronic shutter control circuit 43 in the processor 4B outputs an electronic shutter speed for correcting the variation.
As a result, an image with a constant color balance can be obtained without depending on the variation between the light source devices according to each aperture position.
[0113]
Here, the reason for separately storing the magnification and the electronic shutter speed for each color is as follows. At the time of fluorescence observation, the rotation frequency of the rotary filter 27b is constant (10 Hz), the illumination light diaphragm 24 is fixed, and the size of the light beam is also constant. Therefore, the area of the trapezoidal portion of the surface sequential light passing through the rotary filter 27b, that is, The amount of illumination does not change over time.
[0114]
However, since the spectral characteristics of the optical filter of the rotary filter 27b are different when comparing each color of the surface sequential light, the height of the Kb portion (illumination light intensity) in FIG. 21 and the slopes of the Ka and Kc portions in FIG. The area and shape of the trapezoidal part are different for each color.
For this reason, even if the charge accumulation time is uniformly x times with the electronic shutter, the amount of illumination light for all colors (used for actual imaging) is not uniformly x times.
[0115]
As a result, the color balance of the captured image fluctuates. For the purpose of preventing this, the electronic shutter speed storage element 55 separately stores a magnification and an electronic shutter speed change for each color.
Then, as described with reference to FIG. 12, it is possible to obtain an image in a state where the illumination light amount (contributing to the signal charge) is x times the trapezoidal total illumination light amount for each color of the frame sequential light. ing.
[0116]
The specific operation of the illumination light quantity control by the electronic shutter is as shown in FIG.
In the first step S1, and subsequent steps S2 and S3, it is determined whether the observation mode is fluorescence observation, the amplification factor of the high sensitivity CCD 12b is 1, or the image is brighter than the target value. The illumination light quantity control by the shutter is not performed.
[0117]
On the other hand, if all of these are true, the process proceeds to step S4, and the charge accumulation time magnification is calculated. In the next step S5, the electronic shutter control circuit 43 outputs the magnification to the electronic shutter speed storage element 55, and in the next step S6, the electronic shutter speed information is received from the electronic shutter speed storage element 55. obtain.
[0118]
In the next step S <b> 7, the electronic shutter control circuit 43 calculates the electronic shutter speed for each color of each surface sequential and outputs it to the high sensitivity CCD driver 57.
[0119]
As shown in step S8, the high-sensitivity CCD driver 57 ends the processing by outputting an electronic shutter control pulse to the high-sensitivity CCD 12b in accordance with the irradiation timing of each color on each surface.
[0120]
As described above, in this embodiment, it is determined that the observation mode identification signal is fluorescence observation, the amplification factor of the high-sensitivity CCD 12b is 1, and the image signal input from the color balance correction circuit 35 is brighter than the target value. Only in the case, the electronic shutter speed storage element 55 provided in the light source device 3B is instructed to output an electronic shutter speed at a magnification lower than that of the current frame, and the output electronic shutter speed is received.
[0121]
Here, the electronic shutter speeds of all the frame sequential lights are received. Thereafter, the input electronic shutter speed is converted into an electronic shutter control pulse and transmitted to the high-sensitivity CCD driver 57, and the electronic shutter control pulse of each color is output in accordance with the irradiation timing of each color of the surface sequential light of the rotary filter 27b. .
[0122]
The output electronic shutter control pulse is transmitted to the high-sensitivity CCD 12b via the relay switch 51a and used to control the charge accumulation time.
In the present embodiment, the position of the illumination light diaphragm 24 at the time of fluorescence observation is fixed, but the brightness of the image signal may be adjusted in conjunction with the electronic shutter.
[0123]
In this embodiment, switching between fluorescence observation and normal light observation is described. However, an infrared light observation mode (using three wavelengths of 940 nm, 805 nm, and 805 nm) and a narrow-band light observation mode (center wavelength) are described. May be used in a system including three wavelengths of 415 nm, 540 nm, and 610 nm.
[0124]
In addition, the scope 2B has two CCDs 12 and 12b as in the present embodiment because the scope allows different diameters depending on the site (lower digestive tract, upper digestive tract, bronchi, etc.) to be used. In addition to the scope 2B, a scope having only one CCD may be used.
[0125]
In the present embodiment, the high-sensitivity CCD 12b is used for fluorescence observation, but may be used for other observation modes.
The present embodiment is not limited to when the high sensitivity CCD 12b is used, but may be used when the CCD 12 is used.
[0126]
FIG. 15 shows a configuration when one CCD 12 is employed. The endoscope apparatus 1C has a configuration in which the high-sensitivity CCD 12b and the high-sensitivity CCD driver 57 that generates the drive signal are basically deleted from the endoscope apparatus 1B of FIG. In FIG. 7, the relays 51a and 51b for switching between the two CCDs 12 and 12b and the CCD selector 58 are provided.
[0127]
In this endoscope apparatus 1C, the CCD 12 is used for normal light observation and fluorescence observation.
In addition, in the endoscope apparatus 1D shown in FIG. 16, a high-sensitivity CCD 12b is used instead of the CCD 12 in FIG. 15, and is used for normal light observation and fluorescence observation.
[0128]
The endoscope apparatus 1D of FIG. 16 adopts a high sensitivity CCD 12b and a high sensitivity CCD driver 57 instead of the CCD 12 and the CCD driver 32 in FIG. Further, the high sensitivity CCD driver 57 outputs the information on the amplification factor of the high sensitivity CCD 12b to the electronic shutter control circuit 43 as in the case of FIG.
Thus, as shown in FIGS. 15 and 16, only one CCD may be mounted and used.
[0129]
Since the capacity stored in the scope information storage element 15 is limited, the scope information storage element 15 stores only the model information of the scope 2, and other scope information is provided in the processor 4. It may be stored in a large-capacity memory (not shown), and a setting value may be read and used based on the model information of the scope 2 at the time of activation.
[0130]
Further, the installation location of the observation mode changeover switch 52 is not limited to the operation unit of the scope 2B, but a button provided on a front panel (not shown) of the light source device 3B or the processor 4B, or not shown connected to the processor 4B. It may be a foot switch or a keyboard key.
[0131]
Moreover, the observation mode change-over switch 52 may be in the form of two or more. In addition, when there is no individual difference in the aperture position control accuracy of the light source or in the optical filter, that is, when there is no individual difference in the light source device 3B, the dimming signal output from the dimming circuit 42. May be input to the electronic shutter control circuit 43 and the electronic shutter speed may be corrected based on the dimming signal.
[0132]
In addition, this embodiment may be used as a countermeasure for preventing halation during normal light observation. Further, the brightness adjustment by the electronic shutter may be one in which the brightness can be adjusted by one frame, or may be close to the target brightness by using several frames by a feedback system.
[0133]
Further, when the target value is approached, the magnification may be changed more finely to approach the target value.
The target value may be arbitrarily set by the user by operating a switch on the front panel.
Further, the electronic shutter speed may be common for each color of the frame sequential light, or may be a different value for each color.
[0134]
Further, the lamp 21 of the light source device 3B has a light intensity that decreases as the usage time becomes longer. Accordingly, the area and shape of the trapezoidal portion also vary. May be added as a correction coefficient, and a means for correcting the electronic shutter speed according to the use time may be added.
[0135]
The present embodiment has the following effects.
When observing feeble light as in fluorescence observation, etc., even when the aperture position is opened or fixed at a position close to the open position, the captured light image can be obtained by controlling the amount of illumination light to a desired value using an electronic shutter. An image with appropriate brightness can be obtained while keeping the color balance constant.
[0136]
(Third embodiment)
Next, a third embodiment of the present invention will be described. An object of the present embodiment is to provide an imaging apparatus and an endoscope that can always obtain an image with a constant color balance in an imaging apparatus or an endoscope apparatus that performs brightness adjustment by controlling the amplification factor of a high-sensitivity imaging element. To provide an apparatus.
[0137]
First, the configuration of the present embodiment will be described.
Since this embodiment is similar to the first and second embodiments, different points will be mainly described.
FIG. 17 shows an overall view of an endoscope apparatus 1E according to the third embodiment.
[0138]
The endoscope apparatus 1E includes a scope 2B, a light source device 3E that supplies illumination light to the light guide 8 of the scope 2B, a processor 4E that drives the imaging unit of the scope 2B and performs signal processing on the imaging unit. And an observation monitor 5 for displaying in color the image picked up by the image pickup means.
[0139]
The scope 2B in the present embodiment has the same configuration as that of the second embodiment. That is, the scope 2B includes a light guide 8 that transmits illumination light incident from the light source device 3E to the distal end of the scope 2B, objective optical systems 11 and 11b that receive return light from the subject 10 based on the illumination light, and an optical filter 13. 13b, CCD 12, high-sensitivity CCD 12b, scope 2B model information, CMD applied voltage value-amplification rate characteristics of high-sensitivity CCD 12b, individual variation, corresponding observation mode information, etc. An observation mode changeover switch 52 for switching the observation mode is configured.
[0140]
The light source device 3E does not include the sensor 25 and the electronic shutter speed storage element 55 in the light source device 3B of FIG.
That is, the light source device 3E is provided on the illumination optical path of the lamp 21, such as a xenon lamp that emits light, and a filter turret 23 that can switch a plurality of optical filters by driving the motor 22, and restricts the amount of illumination light. The illumination light stop 24 for rotating the illumination light, the rotary filter 27b for converting the illumination light into a surface sequential light, the motor 28 for rotationally driving the rotary filter 27b, and the rotary filter 27b are moved in a direction perpendicular to the optical axis of the illumination light. And a condensing lens 29 that condenses the surface sequential light via the rotary filter 27b on the incident surface of the light guide 8 of the scope 2B.
[0141]
Further, the processor 4E has a configuration in which a fluorescence image brightness adjustment circuit 63 and an amplification factor storage element 64 are further provided in the processor 4B of FIG.
Specifically, the processor 4E includes a preprocess circuit 33, an A / D conversion circuit 34, a color balance correction circuit 35, a multiplexer 36, synchronization memories 37a, 37b, and 37c, an image processing circuit 38, and a D / A conversion circuit 39a. , 39b, 39c in order of the image signal, the CPU 41, the CCD driver 32, the high sensitivity CCD driver 57, the CCD selector 58, the light control circuit 42, and the brightness adjustment of the image signal at the time of fluorescence observation are performed. For this purpose, a fluorescence image brightness adjustment circuit 63 and an amplification ratio storage element 64 that stores the amplification ratio of the high-sensitivity CCD 12b for each color of frame sequential light are provided.
[0142]
Next, the operation of this embodiment will be described.
The scope 2B used in the present embodiment is assumed to be compatible with two observation modes such as normal light observation and fluorescence observation.
When the power is turned on while the scope 2B is connected to the light source device 3E and the processor 4E, the endoscope device 1E is activated in the normal light observation mode. Simultaneously with the start-up, the scope information storage element 15 of the scope 2B receives the processor 2B model information, the CMD applied voltage value-amplification characteristic of the high-sensitivity CCD 12b, individual variations, corresponding observation mode information, and the like. It is read and stored in the CPU 41 in 4E.
[0143]
When the observation mode changeover switch 52 is pressed in the normal light observation mode, the operation is switched to the fluorescence observation mode by the same operation as in the second embodiment, and the illumination light diaphragm 24 of the light source device 3E is opened or close to being opened. Fixed in position.
[0144]
In the fluorescence image brightness adjustment circuit 63, the observation mode identification signal represents the fluorescence observation mode, and the image signal output from the color balance correction circuit 35 is darker than the target brightness in the brightness adjustment circuit 64. Is determined, the high-sensitivity CCD driver 57 is instructed to increase the CMD applied voltage value in order to increase the amplification factor of the high-sensitivity CCD 12b.
[0145]
Conversely, if it is determined that the brightness is too bright, the high-sensitivity CCD driver 57 is instructed to reduce the CMD applied voltage value in order to reduce the amplification factor of the high-sensitivity CCD 12b. By repeating this several frames, the image signal has appropriate brightness.
[0146]
Here, the CMD applied voltage value-amplification rate characteristic of the high-sensitivity CCD 12b is approximated by an exponential function as shown by the following equation (1), specifically, a curve Ca indicated by a solid line in FIG.
[0147]
(Amplification factor) = A · exp (B · (CMD applied voltage value)) Equation (1)
(A and B are constants determined by CMD)
Based on the equation (1), the amplification factor ratios of the color 1, color 2, and color 3 that are subjected to the surface sequential processing by the rotary filter 27b can be controlled by the CMD applied voltage value. That is, the color balance of the image signal can be controlled by the CMD applied voltage value.
[0148]
For example, if the color balance of the frame sequential light such as color 1, color 2, and color 3 is always kept at (color 1) :( color 2) :( color 3) = 1: 2: 1, the amplification factor The ratio should always be (amplification rate of color 1) :( amplification rate of color 2) :( amplification rate of color 3) = 1: 2: 1. To that end, the CMD applied voltage value ratio is always ( Applied voltage value of color 1): (applied voltage value of color 2): (applied voltage value of color 3) = X: X + C: X (X is an arbitrary, constant satisfying C = log (e / B)) You can do that.
[0149]
However, the CMD applied voltage value-amplification rate characteristic of the high-sensitivity CCD 12b cannot be completely approximated by an exponential function. In particular, in the region where the amplification factor is large, that is, in the region where the CMD applied voltage value is high, the dotted line in FIG. As shown by a curve Cb shown in FIG.
[0150]
Therefore, when adjusting the ratio of the CMD applied voltage values based on the formula (1), a color with a large amplification factor (color 2 in the above example) is replaced with a color with a low amplification factor (in the above example, color 1, It is easier to deviate from the exponential approximation than color 3), the amplification factor ratio and the illumination light quantity ratio are different, and as a result, the color balance of the image signal imaged by the high sensitivity CCD 12b varies.
[0151]
This phenomenon is not a problem when the amplification factor of the high-sensitivity CCD 12b is low in all colors, but it appears remarkably in a state where the amplification factor is high, that is, in a situation where a dark subject is imaged as in fluorescence observation. . In order to prevent this, the following actions are performed.
[0152]
From the high sensitivity CCD driver 57, a signal representing the current CMD applied voltage value is output to the CPU 41. On the other hand, when the endoscope apparatus 1E is activated, the actual CMD applied voltage value-amplification characteristic (curve Cb in FIG. 18) of the high sensitivity CCD 12b is read from the scope information storage element 15 of the scope 2B as described above. And stored in the CPU 41.
[0153]
This is measured in consideration of individual variations of the high-sensitivity CCD 12b at the time of manufacturing the scope 2B, and a plurality of CMD applied voltage values and corresponding amplification factors are stored in the scope information storage element 15 in advance. It has been done.
[0154]
In the CPU 41, as shown in step S11 of FIG. 19, a color identification signal representing the current color of illumination light by the rotary filter 27, the current CMD applied voltage value, the CMD applied voltage value-amplification characteristic, From these three data, the amplification factor of all the color of the field sequential light at the present time is derived.
As a result, the amplification factor of each color and the amplification factor ratio (hereinafter referred to as amplification factor ratio A) of frame sequential light are obtained.
[0155]
Further, the amplification factor ratio storage element 64 of the processor 4E stores in advance the target amplification factor ratio (hereinafter, amplification factor ratio B) of the high-sensitivity CCD 12b, and the observation mode identification signal indicates fluorescence observation. Only in this case, the amplification factor ratio B is output to the CPU 41.
The CPU 41 compares the gain ratio A with the gain ratio B as shown in step S12.
[0156]
When the amplification factor ratio A and the amplification factor ratio B match, the amplification factor ratio is not corrected by the CMD applied voltage value as shown in step S13, and the image brightness adjustment circuit 63 is not corrected. Then, a signal for instructing brightness adjustment by increasing or decreasing the CMD applied voltage value of the high sensitivity CCD 12b is output.
[0157]
On the other hand, when the gain ratio A and the gain ratio B do not match, the CPU 41 sets the CMD applied voltage value of the high sensitivity CCD 12b to the fluorescent image brightness adjustment circuit 63 as shown in step S14. A signal for instructing not to perform brightness adjustment by increase / decrease (that is, stop) is output.
[0158]
Thereafter, in order to bring the amplification factor ratio A closer to the amplification factor ratio B as shown in step S15, a new one for adjusting the amplification factor of the color that is out of the amplification factor (of the actual CMD applied voltage value-amplification factor characteristic). The CMD applied voltage value is derived from the CMD applied voltage value-amplification characteristic.
Then, as shown in step S16, the corrected CMD applied voltage value is output to the high sensitivity CCD driver 57.
[0159]
The high-sensitivity CCD driver 57 outputs the received corrected CMD applied voltage value to the high-sensitivity CCD 12b, so that an image signal whose color balance is corrected can be obtained. Other operations are the same as those of the second embodiment.
[0160]
In the present embodiment, the position of the illumination light diaphragm 24 at the time of fluorescence observation is fixed. However, the brightness of the image signal may be adjusted in conjunction with the adjustment of the applied voltage value of the high sensitivity CCD 12b.
[0161]
In this embodiment, switching between fluorescence observation and normal light observation is described. However, an infrared light observation mode (using three wavelengths of 940 nm, 805 nm, and 805 nm) and a narrow-band light observation mode (center wavelength) are described. May be used for systems including 415 nm, 540 nm, and 610 nm).
[0162]
In addition, since the scope 2B has a different diameter allowed for the scope depending on the site (lower digestive tract, upper digestive tract, bronchi, etc.) to be used, a scope equipped with two CCDs as in the present embodiment. In addition, a scope equipped with only one CCD may be used.
The present embodiment is not limited to when the high sensitivity CCD 12b is used, but may be used when the CCD 12 is used.
[0163]
In the present embodiment, the high-sensitivity CCD 12b is used for fluorescence observation, but may be used for other observation modes. Since the capacity stored in the scope information storage element 15 is limited, the scope information storage element 15 stores only the model information of the scope 2B, and other scope information is provided in the processor 4E. It may be stored in a large-capacity memory (not shown) so that the setting for each scope is read and used at the time of activation.
[0164]
Further, the installation location of the observation mode changeover switch 52 is not limited to the operation unit 7 of the scope 2B, but is illustrated as being connected to a button provided on a front panel (not shown) of the light source device 3E or the processor 4E, or to the processor 4E. Do not use footswitches or keyboard keys.
[0165]
In addition, two or more observation mode changeover switches 52 may be present. The fluorescent image brightness adjustment circuit 63 may be capable of adjusting the brightness in one frame, or may be close to the target brightness using several frames by a feedback system.
[0166]
The target value may be set arbitrarily by the user by operating a switch on the front panel. Further, the amplification factor ratio stored in the amplification factor ratio storage element 64 may be arbitrarily set by the user, or may be in a form in which target values of a plurality of patterns are stored in advance and can be selected. .
[0167]
Further, a function indicating the operation of the second embodiment may be added under close conditions. Further, the amplification factor ratio adjustment is not performed by correcting the CMD applied voltage value, but may be corrected by using an electronic shutter as in the second embodiment.
[0168]
The present embodiment has the following effects.
In an endoscope apparatus that adjusts brightness by controlling the amplification factor of a high-sensitivity image sensor, an image with a constant color balance can be obtained at all times.
[0169]
[Appendix]
1. An endoscope having an elongated insertion portion that can be inserted into a living body;
Light source means for generating surface sequential light for irradiating a subject;
A solid-state imaging device that is provided at a distal end portion of the endoscope and receives an optical signal based on light applied to a subject;
Signal processing means for performing signal processing on an output signal from the solid-state imaging device;
Electronic shutter control means for controlling the charge accumulation time of the solid-state imaging device;
Electronic shutter speed storage means for storing an electronic shutter speed for controlling the amount of illumination by the light source means to a desired value;
An endoscope apparatus comprising:
[0170]
2. The endoscope apparatus according to appendix 1, wherein the solid-state imaging device is a high-sensitivity imaging device having a charge multiplication mechanism inside the device.
3. The endoscope apparatus according to appendix 1 or 2, wherein the electronic shutter speed storage means is a storage element provided in the light source means.
4). The endoscope apparatus according to any one of appendices 1 to 3, wherein the electronic shutter speed storage means is a scope information storage element provided in the endoscope.
[0171]
【The invention's effect】
As described above, according to the present invention, variations in color balance caused by at least one of the light source means, the endoscope, and the solid-state imaging device can be corrected.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an endoscope apparatus provided with a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a rotary filter plate.
FIG. 3 is an explanatory diagram regarding transmission characteristics of an RGB filter.
FIG. 4 is an explanatory diagram of a relationship between an illumination light stop and illumination light intensity.
FIG. 5 is an explanatory diagram of a color balance correction circuit.
FIG. 6 is an explanatory diagram of the operation of the electronic shutter.
FIG. 7 is an overall configuration diagram of an endoscope apparatus provided with a second embodiment of the present invention.
FIG. 8 is a configuration diagram of a rotary filter.
FIG. 9 is an explanatory diagram relating to transmission characteristics of a fluorescence observation filter.
FIG. 10 is an explanatory diagram of a configuration of a high sensitivity CCD.
FIG. 11 is an explanatory diagram of a CMD applied voltage value-amplification rate characteristic of a high sensitivity CCD.
FIG. 12 is an explanatory diagram of a relationship between an illumination light amount and a charge accumulation time.
FIG. 13
FIG. 14 is an explanatory diagram illustrating an operation of a CPU according to the second embodiment.
FIG. 15 is an overall configuration diagram of an endoscope apparatus including a first modification.
FIG. 16 is an overall configuration diagram of an endoscope apparatus including a second modification.
FIG. 17 is an overall configuration diagram of an endoscope apparatus provided with a third embodiment of the present invention.
18 is an explanatory diagram of a theoretical value and an actual measurement value of a CMD applied voltage value-amplification factor characteristic of a high sensitivity CCD. FIG.
FIG. 19 is an explanatory diagram illustrating the operation of a CPU.
FIG. 20 is an explanatory diagram of an illumination light amount and a charge accumulation time during an exposure period.
FIG. 21 is an explanatory diagram of a change in illumination light intensity during an exposure period.
FIG. 22 is a configuration diagram of an illumination light stop.
[Explanation of symbols]
1. Endoscope device
2 ... Electronic endoscope (scope)
3. Light source device
4 ... Processor
5 ... Observation monitor
6 ... Insertion section
7. Operation unit
8. Light guide
10 ... Subject
11 ... Objective optical system
12 ... CCD
15 ... Scope information storage element
21 ... Ramp
24 ... Lighting diaphragm
25 ... Aperture position sensor
26 ... Memory for electronic shutter speed correction
27 ... Rotation filter
29 ... Condensing lens
31a ... R filter
31b ... G filter
31c ... B filter
32 ... CCD driver
33 ... Preprocess circuit
35 ... Color balance circuit
37a, 37b, 37c ... simultaneous memory
38. Image processing circuit
41 ... CPU
42. Light control circuit
43. Electronic shutter control circuit

Claims (8)

In an imaging device that images a subject with a solid-state imaging device based on illumination light emitted from a light source,
Input means for inputting a correction coefficient specific to the light source relating to the amount of illumination light emitted;
Electronic shutter means for controlling the charge accumulation time of the solid-state imaging device based on the input correction coefficient;
An imaging apparatus comprising: In an imaging device that images a subject with a solid-state imaging device based on illumination light emitted from a light source,
Input means for inputting a correction coefficient specific to the light source relating to the amount of illumination light emitted;
Input / output holding means for holding input / output characteristics specific to the imaging unit that includes the solid-state imaging device and outputs a captured image signal;
An electronic shutter means for calculating a correction coefficient specific to the light source and an input / output characteristic specific to the imaging unit held by the input / output holding means, and controlling a charge accumulation time of the solid-state imaging device based on the calculation result; ,
An imaging apparatus comprising: The imaging apparatus according to claim 1, wherein a correction coefficient specific to the light source related to the amount of illumination light is set based on regularity of a change in light amount of the light source. The illumination light emitted from the light source is surface sequential light,
The intrinsic correction coefficient of the light source is provided corresponding to each color of the frame sequential light, and the electronic shutter means controls the charge accumulation time of the solid-state imaging device for each color. The imaging device according to any one of claims 1 to 3. In a light source device used together with an imaging device that images a subject with a solid-state imaging device,
A light source characterized by holding a correction coefficient specific to the light source related to the amount of illumination light emitted from the light source device based on regularity of light quantity change of the light source, and outputting the held correction coefficient to the imaging device apparatus. An endoscope having an elongated insertion portion that can be inserted into a living body;
Light source means for emitting surface sequential light for irradiating a subject;
A high-sensitivity imaging device provided at the distal end of the endoscope and having a charge multiplication mechanism inside the device;
Signal processing means for processing an output signal from the high-sensitivity imaging device;
Amplification characteristic storage means for storing the amplification characteristic of the high-sensitivity imaging device;
Amplification ratio storage means for storing the amplification ratio of the high-sensitivity imaging device between a plurality of colors of the frame sequential light,
Color balance correction means for correcting color balance variation of the output signal based on information stored in the amplification factor characteristic storage unit and the amplification factor ratio storage unit;
An endoscope apparatus comprising: The endoscope apparatus according to claim 6, wherein the color balance correction unit is an electronic shutter control unit. 8. The endoscope apparatus according to claim 1, wherein the endoscope apparatus operates in at least one observation mode of normal light observation, fluorescence observation, infrared light observation, and narrowband light observation. Endoscopic device.

Images