JP2001228412A - Endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve focusing over the entire part particularly in magnification in conformity with the shape, such as ruggedness, of an object to be observed by reverse utilizing the phenomenon of the field curvature of a lens. SOLUTION: The front end of an electronic scope 10 is provided with an objective lens group having movable lenses of a second lens L2 and a third lens L3. Variable magnification is effected and a field curvature characteristic is changed by the movement of these movable lenses. The changing of the field curvature characteristic is executed by operating a field curvature operation switch arranged in an operation section, etc. A microcomputer 15 compares the information from divided regions, decides whether the foci in the central part and peripheral part of the image are within a prescribed range or not and if the entire part of the image is focused, the microcomputer is capable of executing control so as to form and output a static image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus, and more particularly to an endoscope apparatus capable of changing a field curvature characteristic when an object to be observed is optically enlarged.

[0002]

2. Description of the Related Art In recent years, in an electronic endoscope apparatus and the like, a movable lens for zooming is arranged in an objective lens system at the distal end of a scope, and an image of an object to be observed is optically enlarged. . Then, this optically enlarged image is a CCD (Char
ge Coupled Device).
By performing various types of image processing on the video signal (image signal) output from the CD by the processor device, an enlarged image of the object to be observed is displayed on the monitor.

FIG. 7 shows an example of an enlarged display image formed by the electronic endoscope apparatus. FIG. 7A shows a display on a monitor, and FIG. It is a cross section of an observation body. The FIG. 7 (A) but is an enlarged view of a recess K ₁ in the affected area in a circular mask of the monitor 1 M, in zooming mechanism of the endoscope noted by magnifying up 70-100 fold The part can be observed.

[0004]

However, in an objective lens system of an endoscope, when a part having irregularities is particularly enlarged, a peripheral part or a central part becomes out of focus due to astigmatism, field curvature aberration and the like. was there. For example, FIG.
To describe the case of, when the subject is in focus at the center portion of the recess K ₁ which is enlarged, when the peripheral portion may become out of focus, is in focus in the peripheral portion of the recess K _1, the central portion A phenomenon such as blurring occurs, and the focus may not always be in a uniform state over the entire image. In such a state, there is an inconvenience that a sufficiently satisfactory image cannot be obtained especially in a still image photographed for recording.

The present invention has been made in view of the above problems, and an object of the present invention is to make use of the field curvature characteristic of a lens in a reverse manner and to cope with the shape of unevenness or the like of an object to be observed. It is an object of the present invention to provide an endoscope apparatus which can obtain an image in which the overall focusing is improved.

[0006]

According to a first aspect of the present invention, there is provided an endoscope apparatus disposed at a distal end portion of an endoscope, wherein a movable lens is moved to move the movable lens. Objective lens group capable of changing (field curvature characteristics including astigmatism), field curvature operation means for operating to change the field curvature characteristic of the objective lens group, and field curvature operation Driving means for driving the movable lens based on operation of the means.

According to a second aspect of the present invention, there is provided an objective lens group disposed at the end of an endoscope and capable of changing a field curvature characteristic by moving a movable lens; Driving means for driving the lens, and dividing the imaging area of the objective lens group into a plurality of parts, and comparing the information from the divided areas to determine whether the focus of the central part and the peripheral part is within a predetermined range. Means, and a control circuit for executing various controls based on the output of the determination means.

According to a third aspect of the present invention, in the objective lens group, a lens for field curvature is incorporated together with a variable power lens for changing an image magnification, and drive control for both variable power and a change in field curvature characteristics is performed. It is characterized by performing. The invention according to claim 4 is characterized in that the control circuit controls to output a still image when the focus of the central portion and the peripheral portion is within a predetermined range based on the determination by the determination means.

According to the above configuration, for example, by providing two movable lenses (or lens groups) in the objective lens group, both the variable power operation and the field curvature (characteristic change) operation can be performed. Be composed. Then, when the field curvature operation switch arranged on the operation unit or the like is operated, the movable lens is driven by an actuator or the like, whereby the field curvature characteristic can be changed. This curvature of field can be generated in the under direction and the over direction with respect to the reference plane, and the focus can be adjusted to the concave shape by the operation in the under direction and the convex shape by the operation in the over direction. It becomes possible.

According to the second aspect of the present invention, whether or not the center portion and the peripheral portion are in focus is compared by the comparing means, and whether or not the focus is achieved, that is, the in-focus state is supplied to the control circuit. This control circuit outputs, for example, a still image when the whole is in focus. That is, when the freeze switch is pressed, the still image is not output when the center portion and the peripheral portion are out of focus, and the still image only when the focus is in focus can be displayed on the monitor and recorded. .
The information on the in-focus state may be displayed on a monitor or the like, or may be notified by other means.

[0011]

FIG. 1 shows the configuration of an electronic endoscope apparatus according to an embodiment, and FIG. 2 shows the configuration of the objective lens group of FIG. In FIG. 1, a first lens (group) is provided at the tip of an electronic scope (electronic endoscope) 10.
An objective lens group (the object side is on the left side in the figure) composed of L ₁ , a second lens (group) L ₂ , and a third lens (group) L ₃ and a CCD 11 as an image pickup device are provided. The so-called floating is used, and for example, a configuration as shown in FIG. 2 can be employed.

[0012] As shown in FIG. 2, the first lens L ₁ is made of two left observation window lens and (plano-concave) plano-convex lens, but is arranged as a fixed lens, the second lens L ₂ is mainly one plano-convex lens for the zooming function, and the third lens L ₃ is made mainly of two plano-concave lens and a biconvex lens for changing the curvature of field characteristic, it is disposed in both of the movable lens . According to this objective lens group, both the second lens L ₂ and the third lens L ₃ are relatively moved in the optical axis direction, so that the image can be zoomed and the field curvature can be generated. .

In FIG. 1, the second lens L ₂ has an actuator 12A, and the third lens L ₃ has an actuator 1A.
2B, these actuators 12
Examples of A and 12B include various linear actuators such as a piezoelectric actuator and an electrostatic actuator,
As shown in -75262 or the like, it is possible to use a configuration in which a linear transmission member is rotationally driven by a motor, and this rotational motion is converted into linear motion of the lenses L ₂ and L ₃ . A microcomputer 15 is connected to these actuators 12A and 12B via a driver 14, and under the control of the microcomputer 15, a variable power operation and a field curvature operation are executed.

In addition to the freeze switch 16 for outputting a still image, a zooming switch 17 for operating in the Near direction and the Far direction, and a zoom switch 17 for operating in the under direction and the over direction are provided on the operation unit 10C and the like of the electronic scope 10. A field curvature switch 18 (two operations) to be operated is arranged for each of them, and these operation signals are output to the microcomputer 15. Accordingly, the microcomputer 15 controls the enlargement and reduction of the image in accordance with the control signal from the variable power switch 17, and lowers the curvature of field (the outer peripheral portion with respect to the center with respect to the center) by the control signal from the curvature switch 18. The direction can be changed in the direction in which the focal position moves to the object side) and in the direction in which the focal position of the outer peripheral portion moves to the opposite side to the object with respect to the center.

FIG. 3 shows an example of the characteristic of the field curvature set in this example. FIG. 3 shows the focal position in the vertical V direction (height direction) from the center point of the imaging surface of the CCD 11. It is a representation. For example, as shown in FIGS. 2A to 2C, the second lens L ₂ and the third lens L
_{When 3} is relatively moved by a predetermined amount, an image plane of an arbitrary amount from under (characteristic J _a ) at which the image surface is tilted to the object side to over (characteristic J _z ) at which the image surface is tilted to the opposite side. Curvature can be generated and this property can be changed.

In FIG. 1, a timing generator (TG) 20 for supplying a signal for reading a video signal is connected to the CCD 11, and a CDS (correlated double sampling) / AGC is used as a video signal processing system.
(Automatic gain control) Circuit 22, A / D converter 23, DSP 24 for performing various digital processes such as white balance, gamma correction, contour correction, etc., frame memory 25 for temporarily storing images, D / A converter 26, video An encoder (ENC) 27 that performs an output process in accordance with the format of a signal on a display device is arranged in a processor device or the like. The above encoder 27
Is output to the monitor 28.

In this example, it is determined whether or not the center of the image or the screen is in focus and the periphery thereof is in focus.
For this determination, a band-pass filter (BP) that extracts a high-frequency component (contrast data of an edge portion) of the video signal
F) 30 is provided after the A / D converter 23, and the output of the BPF 30 is supplied to the microcomputer 15. The microcomputer 15 performs various controls of the device functions and determines the focus state.

That is, as shown in FIG. 5, an image (screen) area is divided into a center part a and four peripheral parts b, c, d, and e. High-frequency components are extracted and, for example, all regions (not all, a and b
If any of the high-frequency components (e.g., any of -e) can be equal to or greater than the reference value, it is determined that the entire screen is in focus.
In this example, when a still image is selected by operating the freeze switch 16, control is performed such that a still image is output only when the in-focus state is determined.

The embodiment has the above configuration, and its operation will be described. In this device, the object to be observed is captured by the above-described objective lens group (L _{1 to} L ₃ ), and when the image of the object to be observed is captured by the CCD 11, the video signal is read by the read signal of the timing generator 20. , C
After being subjected to the correlated double sampling and the amplification processing in the DS / AGC circuit 22, various processing is performed in the DSP 24 as a digital signal. The video signal thus formed is output to the monitor 28 via the encoder 27, so that a moving image of the observation target is displayed on the monitor 28.

[0020] Then, when operating the zoom switch 17 of the electronic endoscope operation portion 10C, the second lens L ₂ and third lens L ₃ is a microcomputer 15, a driver 14 and an actuator 12A, is moved controlled by 12B, Near
Enlarged image from the basic image is obtained by focusing in the direction,
By focusing in the Far direction, reduced images in the direction returning to the basic image are obtained, and these images are captured by the CCD 11. However, in the observed object having unevenness when enlarged in the near direction, the peripheral portion may not be focused due to the curvature of field.

In such a case, the peripheral area can be focused by operating the field curvature switch 18. That is, when the field curvature switch 18 is operated in the over direction, as shown in FIGS.
The second lens L ₂ and the third lens L ₃ are connected to the actuator 12
A and 12B are controlled to move from the under focus position (Ja) to the over focus position (Ja) in FIG.
The curvature of field that changes to z) is provided. When the lens is operated in the under direction, a field curvature characteristic that changes from the over focal position (Jz) to the under focal position (Ja) is set by the reverse movement of the lenses L ₂ and L _3. You.

For example, as shown in FIG.
Observation body is depression K₁If it is, the characteristic J of the under₁
By giving the field curvature of₁Suitable for the shape of
Focus adjustment is performed, and is also shown in FIG.
As shown in FIG. _TwoIf it was over
Characteristics J_TwoBy giving the field curvature of _Two
Focusing suitable for the shape of is performed.

On the other hand, when the freeze switch 16 of the electronic scope operation unit 10C is operated, the microcomputer 15
The still image formation control is performed by the
The still image is displayed on the monitor 18 by writing the video signal at the time of pressing on the frame memory 25, and this still image is also output to a recording device such as a hard copy. In this example, at the time of this still image output, the microcomputer 15 determines whether or not the entire image is in focus, based on the high frequency component input from the BPF 30.

FIG. 6 shows the operation of the microcomputer 15 at this time. In Step 101, the high-frequency component of the image center portion a described with reference to FIG. 5 is extracted. Is greater than or equal to (extracted value> reference value)
Is compared. On the other hand, in Step 103, high frequency components of the image peripheral parts b, c, d, and e in FIG. 5 are extracted, and the next STEP 104 compares whether or not the extracted value is larger than a reference value (extraction value> reference value). I do. Next, in Step 105, it is determined whether or not all the comparison outputs of the regions a, b, c, d, and e are YES (abcde = YES?). At this time, a focus signal (overall focus coincidence signal) is output (Step 106).

When the in-focus signal is output in Step 106, the microcomputer 15 permits the output of a still image. That is, when the in-focus signal is not obtained even when the freeze switch 16 is pressed, the still image is not output, and the image quality of the still image is improved.

The in-focus state of the entire image is displayed (or reported) on a monitor or an operation panel of a processor device.
It is also possible to adopt a configuration in which When displaying the in-focus state, the microcomputer 15 does not limit the output at the time of forming a still image, and performs the same control as before, and the operator confirms the in-focus state displayed on the monitor. The freeze switch 16 may be pressed.

[0027]

As described above, according to the first aspect of the present invention, the objective lens group for changing the field curvature characteristic and the field curvature operation switch for operating the field curvature change amount are provided. Since the field curvature is generated by the operation through the driving means in the opposite manner to the normal case, by providing an under or over field curvature in accordance with the shape of the unevenness or the like of the observed object, especially at the time of enlargement. The out-of-focus state of the peripheral portion of the image can be resolved, and a good image can be obtained as a whole.

According to the second aspect of the present invention, in addition to the objective lens group for changing the curvature of field, the determination means for determining whether the focus of the central portion and the peripheral portion is within a predetermined range is provided. There is an advantage that the setting state of the field curvature characteristic can be determined. According to the fourth aspect of the present invention, since a still image is output based on the determination by the determination means, it is possible to obtain a high-contrast still image in which the entire uneven portion image is in focus.

[Brief description of the drawings]

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

FIGS. 2A to 2C are diagrams illustrating a configuration of an objective lens group and an operation state thereof according to the embodiment.

FIG. 3 is a graph illustrating a state (amount) of field curvature caused by the objective lens group according to the embodiment;

FIGS. 4A and 4B are diagrams showing the relationship between the uneven shape of the object to be observed and the field curvature characteristics that can be generated. FIGS.

FIG. 5 is a diagram showing divided regions to be compared by focus determination means of the entire image.

FIG. 6 is a flowchart illustrating a focus determination operation in the microcomputer of the embodiment.

FIG. 7 is a diagram showing a display state (FIG. (A)) of the object to be observed on a monitor enlarged in the conventional electronic endoscope apparatus (FIG. (A)) and a cross section (FIG. (B)) of the object to be observed.

[Explanation of symbols]

1, 28 monitor, 10 electronic scope, 11 CCD, 12A, 12B actuator, 15 microcomputer, 16 freeze switch, 17 variable power switch, 18 field curvature switch, 30 band-pass filter (BPF) ), L ₁ ... the first lens (fixed lens), L ₂ ... the second lens (movable lens), L ₃ ... third lens (movable lens).

Claims (4)

[Claims] 1. An objective lens group disposed at a distal end of an endoscope and capable of changing a field curvature characteristic by moving a movable lens, and operating to change the field curvature characteristic of the objective lens group. An endoscope apparatus comprising: a field curvature operation device for driving the movable lens based on an operation of the field curvature operation device. 2. An objective lens group disposed at the end of the endoscope and capable of changing a field curvature characteristic by moving a movable lens, and a driving means for driving a movable lens for field curvature of the objective lens group Determining means for dividing the imaging region of the objective lens group into a plurality of parts and comparing information from the divided regions to determine whether the focus of the central part and the peripheral part is within a predetermined range; And a control circuit for executing various controls based on the output of the endoscope. 3. The objective lens group according to claim 1, further comprising a variable power lens for changing the magnification of the image and a lens for curvature of field, and driving control of both the variable power and the change of the curvature of field are performed. The endoscope apparatus according to claim 1 or 2, wherein 4. The control circuit according to claim 2, wherein the control circuit controls to output a still image when the focus of the central portion and the peripheral portion is within a predetermined range based on the determination by the determination means. Or the endoscope apparatus according to 3.