JP2003102675A - Electronic endoscope apparatus having optical variable power function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a reddish picture in an area where is not illuminated directly by eliminating the influence of luminous intensity distribution in photographing of a magnified image so as to obtain the picture of uniform brightness. SOLUTION: In an electronic endoscope which picks up an image magnified by driving of a movable lens 16 of an optical variable power mechanism by a CCD 26 and monitor-displays a picture of a body to be observed, an averaging circuit 34 averages the luminance signal of 32 pixel units, e.g. a coefficient calculation circuit 36 compares these average values with each horizontal line and calculates a coefficient by which these are equalized, and a multiplier 39 multiplies this coefficient to a chrominance signal. Thus, influence of luminous intensity distribution varying in the case of magnifying photographing is eliminated to obtain a picture of uniform brightness. By providing a red component cut filter 46 for cutting the long wave length side of the red zone of the illumination light, reddishness is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus equipped with an optical zooming mechanism, and more particularly to an electronic endoscope apparatus in which a scope distal end is brought close to an object to be observed while driving a movable lens to capture an enlarged image. Image processing of an endoscope.

[0002]

2. Description of the Related Art An electronic endoscope apparatus irradiates illumination light and captures an image of an object to be observed captured through an objective optical system.
An image pickup device such as an arge coupled device is used to display an image of the observed object on a monitor. In recent years, however, in this type of electronic endoscope apparatus, a movable lens (varifocal) is used in the objective optical system. The movable lens is moved back and forth by a variable power mechanism to optically magnify the image of the body to be observed. The magnified image is image-processed and displayed on a monitor or the like, and the magnified image enables good observation of the details of the region of interest.

[0003]

However, in the electronic endoscope apparatus having the optical variable power mechanism, an image having a uniform brightness can be obtained due to the changing light distribution in close-up photography for obtaining a magnified image. There was a problem of not having. That is, FIG. 6 shows a state in which the scope distal end portion is brought close to the object to be observed, and as shown in FIG. Is an illumination window (lens) 4 that emits the light guided by the light guide 3.
a, 4b, and an observation window (lens) 6 of the objective optical system 5 are arranged.

At a distance that does not use the above-mentioned scaling function.
Is the light S from the illumination windows 4a and 4b.₁, S₂With overlapping
The object 1 to be observed is irradiated, but the proximity shown in FIG.
When the tip 2 is set to the distance Da,
Light S from the bright windows 4a and 4b ₁, S₂6 does not overlap,
As shown in (B), the object to be observed 1 is directly irradiated with light.
A place z (a region indicated by a dotted line) not to be generated occurs.

Further, in the illumination area of the lights S ₁ and S ₂ , the light intensity decreases from the center of the light spot toward the periphery,
Even at the location z, the amount of light decreases as the distance from the illumination position increases, and a distribution of light distribution to the observed object occurs.
In addition, when the variable magnification function is used, the in-focus distance changes depending on the magnification, so that the intensity of the illumination light on the observed object 1 changes and the light distribution distribution also changes at the same time. Unlike normal photography, when performing close-up photography using a variable power mechanism, there is a problem that the existence of the above-mentioned light distribution has a great influence, and it may be difficult to obtain an image of uniform brightness.

Further, the movable lens is, for example, a magnifying end (Nea).
drive to the r end), and the scope tip 2 as shown in FIG.
When the light is extremely close to the object to be observed 1, the light S on both sides at the position z where the light of the object to be observed 1 in FIG.
₁ and S ₂ are diffused inside the observed body 1 (for example, in the mucous membrane layer), and a reddish image is formed by imaging with an electronic endoscope in which the living body is the observed body. There is.

The present invention has been made in view of the above problems, and an object thereof is to obtain an image of uniform brightness without taking the influence of the light distribution distribution in photographing a magnified image. An object of the present invention is to provide an electronic endoscope apparatus having an optical zooming mechanism capable of improving a reddish image in an unilluminated area.

[0008]

In order to achieve the above object, an electronic endoscope apparatus equipped with an optical variable magnification mechanism according to the present invention incorporates a movable lens in an objective optical system and drives the movable lens. A variable power mechanism for optically enlarging an image by means of a signal forming circuit for forming a luminance signal and a color signal on the basis of a signal output from the image pickup device via the objective optical system, and a signal forming circuit The output luminance signals of a predetermined number of pixels are averaged, and the average value of the predetermined number of pixels is compared for each horizontal line, and the coefficient for eliminating the unevenness of the image brightness due to the distribution of illumination light is calculated. It is characterized by including a coefficient calculating circuit for calculating and a multiplier for multiplying the color signal output from the signal forming circuit by the coefficient from the coefficient calculating circuit. The invention according to claim 2 is characterized in that a red component cut filter which is arranged on a supply line of illumination light for illuminating an object to be observed and cuts a long wavelength side of a red band of the illumination light is provided.

According to the above arrangement, the average value of a predetermined number of pixels in the horizontal line is obtained, and the coefficient for making these average values constant (uniform) in the horizontal line is calculated in the unit of the predetermined number of pixels. To be done. And this coefficient is
The respective color signals, that is, the R, G, and B signals (or the luminance signal and the color difference signal) are multiplied, thereby eliminating the unevenness of the illumination light caused by the different light distributions at different magnifications.

According to the second aspect of the invention, since the red component cut filter cuts the red long wavelength side,
The reddish image (reddish state) of the living body to be observed is improved, and the mucous membrane, blood vessels, and other tissues can be well distinguished and displayed. When this filter is used, the light quantity becomes insufficient, and the light distribution is also changed. This light quantity shortage (and light distribution characteristics) is eliminated by the coefficient multiplication process, resulting in uneven brightness and red image. The advantage is that the porosity is improved at the same time.

[0011]

1 shows the configuration of an electronic endoscope apparatus according to an embodiment. This electronic endoscope apparatus is of a simultaneous type and includes a scope 10, a processor unit 11,
The light source device 12 and the monitor 14 are included. This Figure 1
In the above device, the illumination windows 4a, 4a
b, an observation window 6 is arranged, and the illumination windows 4a, 4b
A light guide 3 guided from the light source device 12 is optically connected to the.

Although the observation window 6 constitutes an objective optical system, a movable lens 16 is provided as a part of the objective optical system, and the movable lens 16 is held by a moving mechanism 18.
Connected. A motor drive unit 22 is connected to the moving mechanism 18 via a rotating linear transmission member 20, and the motor drive unit 22 is controlled by a microcomputer 24. That is, the motor of the motor drive unit 22 is rotated based on the operation of the variable power switch arranged on the operation unit of the scope 10 and the rotation is transmitted to the moving mechanism 18 via the linear transmission member 20. The mechanism 18 converts the rotary motion into a linear motion to move the movable lens 16 back and forth. This movable lens 1
6 is each position from the Far end to the Near end (for example, 2
Drive control is carried out to 56 control positions), whereby optical magnification is executed.

On the rear side of the objective optical system including the movable lens 16, a CCD 26 which is an image pickup device is provided.
In the CD 26, the image of the object to be observed is captured through a color filter [eg, Mg (magenta), G (green), Cy (cyan), Ye (yellow)] in pixel units. That is, when the light from the light source device 12 is applied to the object to be observed from the tip of the scope 10 through the light guide 3, the object to be observed is imaged by the CCD 26.

In the subsequent stage of the CCD 26, a CDS (Corr
elated Double Sampling / A
GC (Automatic Gain Control) 2
8 are arranged, and this CDS / AGC 28 is a CCD
Correlated double sampling is performed on the output signal of 26 and predetermined amplification processing is performed. The CDS / AGC 28 is provided with a DSP (Digital Signal Processor) 30 via an A / D (analog / digital) converter 29.

The DSP 30 includes a signal processing circuit 32 for performing various processes such as white balance and gamma correction.
Is provided, and in this signal processing circuit 32, the CCD
The Y (luminance) signal and the color difference (C) signals of R (red) -Y and B (blue) -Y are calculated by color conversion from the signals obtained through the 26 color filters of Mg, G, Cy, and Ye. Is formed. In addition, Y output from the signal processing circuit 32
A line memory 33 that stores a signal for each horizontal line, an averaging circuit 34 that sequentially obtains an average value of the horizontal line signal read from the line memory 33, for example, for every 32 pixels (other pixel numbers may be used). A line memory 35 that sequentially stores the average values calculated by the digitizing circuit 34, and a coefficient calculation unit that compares the average value data of the line memory 35 and calculates a coefficient for matching the levels of these average values with a predetermined level. 36 is provided.

FIG. 2 shows the averaging pixels in the CCD 26. In the image pickup surface area 26S of FIG.
Although a screen area of 8 pixels and 494 lines is set, the average value of the Y signal is calculated by the averaging circuit 34 in units of 32 pixels in the horizontal line of 768 pixels. As a result, the average value of 24 blocks is obtained, and the coefficient calculating unit 36 obtains the coefficient with which the average value of the 24 blocks is constant (uniform).

FIG. 3A shows the horizontal line 32 of FIG.
An average value in pixel units is shown. For example, in the horizontal line Lc at the center of FIG. 2, the distribution shows a lower value toward the center as shown in the figure, and this average value distribution corresponds to the light distribution distribution. . In the coefficient calculation unit 36, the coefficient for matching with the maximum value e ₁ of these average values is calculated,
The coefficient as shown in (B) is obtained in units of 32 pixels. In this coefficient calculation, a coefficient for matching the average value e ₂ instead of the maximum value e ₁ may be obtained.

On the other hand, an RGB matrix circuit 38 which converts the color difference signals output from the signal processing circuit 32 into R (red), G (green) and B (blue) signals, and is output from this RGB matrix circuit 38. Multiplier 3 for multiplying the R, G, B signals by the coefficient output from the coefficient calculating section 36.
9, R, G, B signals output from the multiplier 39
A color conversion circuit 40 for returning the -Y and BY color difference signals is provided. That is, the multiplier 39 multiplies the R, G, B signals by the coefficient obtained from the Y signal in units of 32 pixels on the horizontal line, thereby eliminating the influence of the light distribution.

Further, the processor unit 11 is provided with the above DS.
A signal processing circuit 42 for inputting the Y signal and the color difference C signal output from P30 and a D / A converter 43 are provided. The signal processing circuit 42 performs various signal processing for outputting to the monitor 14. .

Further, in the light source device 12, the lamp 45, the red component cut filter 46, the light amount diaphragm 47, and the condenser lens 4 are provided.
8 is provided, and the light output from the condenser lens 48 is supplied to the light guide 3. FIG. 4 shows the spectral transmittance characteristic of the red component cut filter 46. The filter 46 has a spectral transmittance of 630 n, for example.
It has a characteristic such that it has a half value at m (± 10 nm) and 0 at 670 nm. According to this red component cut filter 46, as shown in FIG.
As shown in FIG.
Half or more of the wavelength component of 0 nm or more is cut.

The embodiment has the above-mentioned structure, and its operation will be described below. First, according to the above-described optical variable power mechanism, the movable lens 16 is moved back and forth by operating the variable power switch provided on the operation unit of the scope 10 and the like, and an optically enlarged image can be obtained. it can. here,
As the movable lens 16 is moved from the Far end toward the Near position, the in-focus position shifts toward the near side, and the tip of the scope approaches the observed object. Then, the light output from the light source device 12 is applied to the observed object through the light guide 3, and the illumination light of the observed object is distributed at the position of the movable lens 16, that is, the focusing distance. The distribution will be different.

On the other hand, the object to be observed illuminated by light is the CCD 26.
The output signal from the CCD 26 is captured by the CDS
/ AGC28 sampled and amplified, A
It is supplied to the DSP 30 via the / D converter 29. In the DSP 30, the signal processing circuit 32 performs various kinds of image processing on the video signal to form a Y (luminance) signal and C (color difference) signals of RY and BY.

Next, the Y signal is stored in the line memory 33 for each horizontal line, and in the averaging circuit 34 in the subsequent stage, as described with reference to FIG.
It is averaged in pixel units. After that, 24 blocks (7
Twenty-four average values (of 68 pixels) are stored in the line memory 35, and these average values are compared by the coefficient calculation unit 36 in the subsequent stage, and, for example, a coefficient for matching the maximum value e ₁ of FIG. Is calculated. This coefficient calculation is performed when the difference between the average values of the blocks is greater than or equal to a certain value (threshold value), and for example, a coefficient as shown in FIG. 3B is calculated.
Then, these coefficients are given to the multiplier 39.

On the other hand, C output from the signal processing circuit 32
The signal is converted into R, G, B signals by the RGB matrix 38 and then supplied to the multiplier 39.
At 9, the above coefficients are multiplied for each of the R, G, B signals. That is, FIG. 2 shows a state in which the illumination lights S ₁ and S ₂ do not overlap each other at the time of close-up photography, and the middle part thereof is not directly exposed to light, and the center line Lc of FIG.
Then, the light distribution shown in FIG. In this light distribution, the coefficients for matching each average value to the maximum value e ₁ are 1.00, 1.00, 1.10, in units of 32 pixels, as shown in the figure.
1.10, 1.15, 1.20, 1.25 ... and these coefficients are R,
The G and B signals are multiplied. This eliminates the influence of variations in illumination light due to the light distribution shown in FIG.

R, G, B output from the multiplier 39
The signal is converted back into a C signal by the color conversion circuit 40 and supplied to the signal processing circuit 42. In this signal processing circuit 42, an image of the observed object is displayed on the monitor 14 via the D / A converter 43 by performing other processing and output processing. As a result, in the image magnified by the magnification changing mechanism, the non-uniformity of the light illumination caused by the light distribution changing with the focusing distance (magnification) is eliminated.

Further, in the microcomputer 24, the process of calculating the coefficient and the multiplication is performed by the movable lens 1 in the variable power mechanism.
When 6 is at the Far end, the process is not executed, but is controlled to start from the lens position when driven from the Far end to the Near end or a predetermined lens position (for example, an intermediate lens position). That is, in this example, the influence of the light distribution of the illumination light on the brightness of the screen in close-up photography during zooming is eliminated.

FIG. 5 shows the spectral reflectances of the mucous membrane and blood when the red component cut filter 46 is arranged in the light source device 12. In this example, the red component cut filter 46 is shown.
The reddish image is resolved satisfactorily. In FIG. 5, the spectral reflectance curve of normal gastric mucosa is represented by C ₁ (solid line), the spectral reflectance curve of blood is represented by C ₂ (dotted line), and the spectral reflectance curve C ₂ of blood has a wavelength of 600 nm or more. Grows very large. Here, the region S ₁ surrounded by the curves C ₁ and C ₂ at wavelengths from 400 nm to 600 nm is a component that contributes to the contrast between the mucous membrane and blood or other tissues, and the curve C ₁ from wavelengths before 600 nm to wavelengths longer than 600 nm. The region S ₂ surrounded by C ₂ and C ₂ is a component that causes light scattering in the submucosa and rather lowers the contrast between the mucous membrane and blood or the like.

In this example, by providing the red component cut filter 46, the wavelength band of 670 nm or shorter can be removed and the region S ₂ can be reduced to the region S ₃ . This has the advantage that not only the red component in the image is reduced, but also the wavelength component that causes a decrease in contrast between the mucous membrane and blood is removed, and these can be displayed with good contrast. Further, when the red component cut filter 46 is used, the light amount becomes insufficient and the light distribution characteristic changes, but the light amount insufficient (and the light distribution characteristic) is eliminated by the coefficient multiplication, and the brightness is reduced. The unevenness and the reddishness of the image are simultaneously improved.

In the above embodiment, the R, G, B signals formed by the RGB matrix circuit 38 are multiplied by the coefficient, but the color difference signal (R
By multiplying -Y and BY) by a coefficient, the influence of the light distribution can be similarly improved.

[0030]

As described above, according to the invention of claim 1, luminance signals of a predetermined number of pixels are averaged, each average value is compared for each horizontal line, and a coefficient that makes them uniform is determined. Since the color signal is calculated and the color signal is multiplied by the predetermined number of pixels, it is possible to eliminate the influence of the light distribution distribution that changes at the time of magnified photography and obtain an image of uniform brightness.

When a red component cut filter for cutting the long wavelength side of the red band of the illumination light is provided as in the second aspect of the invention, the light amount due to this red component cut filter is insufficient (and the distribution at that time is reduced). (Light characteristics) is also eliminated, and a reddish image in a region that is not directly illuminated can be favorably improved. In addition, the wavelength components that cause a decrease in the contrast between the mucous membrane and blood are removed, and these are displayed with good contrast, and a magnified image that is easy to observe can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of an electronic endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light irradiation state on an image pickup surface of an image pickup element according to an embodiment and a pixel number as a unit of coefficient calculation.

3 is a diagram showing an average value in 32 pixel units [FIG. (A)] and a coefficient in 32 pixel units [FIG. (B)] of the center line Lc of FIG. 2;

FIG. 4 is a characteristic diagram showing the spectral transmittance of the red component cut filter used in the embodiment.

FIG. 5 is a diagram showing spectral reflectance characteristics of normal gastric mucosa and blood when a red component cut filter is used in the embodiment.

FIG. 6 is a diagram showing a light irradiation state [Figure (A)] and a display state [Figure (B)] of the observed object when the distal end of the scope is brought close to the observed object.

[Explanation of symbols]

4a, 4b ... Illumination window, 6 ... Observation window, 16 ... Movable lens, 18 ... Moving mechanism, 24 ... Microcomputer,
26 ... CCD, 30 ... DSP, 33, 35
... line memory, 34 ... averaging circuit, 36 ... coefficient calculating section, 38 ... RGB matrix, 39 ... multiplier, 40
... Color conversion circuit, 46 ... Red component cut filter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI theme code (reference) H04N 7/18 H04N 7/18 M (72) Inventor Daisuke Ayame 1-324 Uetakecho, Saitama City Saitama Prefecture Fuji Photo Optical Co., Ltd. F-term (reference) 2H040 BA03 BA13 CA22 GA02 4C061 AA00 BB02 CC06 DD00 FF40 LL02 NN01 NN05 PP12 QQ09 RR06 RR14 RR17 RR26 SS21 SS23 TT01 TT03 5C022 A04 0913 FC16 HA12

Claims (2)

[Claims] 1. A variable magnification mechanism for incorporating a movable lens into an objective optical system to optically magnify an image by driving the movable lens, and a signal output from an image pickup device via the objective optical system. , A signal forming circuit that forms a luminance signal and a color signal, and the luminance signals of a predetermined number of pixels output from this signal forming circuit are averaged, and the average value of the predetermined number of pixels is compared for each horizontal line to determine the illumination light. A coefficient calculation circuit for calculating a coefficient for eliminating uneven brightness of an image due to the light distribution of the image, and a multiplier for multiplying the color signal output from the signal forming circuit by the coefficient from the coefficient calculation circuit. An electronic endoscope apparatus provided with an optical zooming mechanism including. 2. The red component cut filter, which is arranged in a supply line of illumination light for illuminating an object to be observed and cuts a long wavelength side of a red band of the illumination light. Electronic endoscope device equipped with the optical zoom mechanism of.