JPH11169336A - Magnifying endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a drive mechanism of an objective lens in a magnifying endoscope which is so arranged to drive an objective lens in an objective optical system provided in an endoscope on the optical axis thereof. SOLUTION: A lens holding cylinder 16 of object lenses 17 respectively mounted in optical cylinders 11, 12 and 13 of an objective optical system 3 of an endoscope and a CCD holding cylinder 18 of a CCD image sensor 19 are elastically supported in the direction of the optical axis thereof by a first spring 22 and a second spring 23 made up a shape memory material sandwiching a third spring 24. The first and second springs 22 and 23 are elctrically energized to raise temperature by heat generated by a self-resistance so that the spring coefficients of the first and second springs 22 and 23 are made larger than the spring coefficient of the third spring 24. Thus, the objective lens 17 and the CCD image sensor 19 are moved separately in the direction of the optical axis thereby enabling enlarged imaging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnifying endoscope having a variable magnification function in an objective optical system, and more particularly to a simplification of a variable magnification mechanism.
The present invention relates to a miniaturized magnifying endoscope.

[0002]

2. Description of the Related Art A magnifying endoscope having a variable power function in an objective optical system requires a mechanism for moving an objective lens in an optical axis direction in an objective lens optical tube. Such a variable magnification mechanism includes a wire mechanism that moves the objective lens by remote control using a wire extending from the endoscope operation unit to the objective lens, or energization of an electrostatic actuator built in the objective optical system. The objective lens is supported by a piezoelectric element such as a piezo element, and the objective lens is moved by deformation of the piezoelectric element when the voltage applied to the piezoelectric element is controlled. There has been proposed a piezoelectric mechanism or the like that performs the following. However, in the above-described electrostatic actuator mechanism, it is necessary to apply a certain high voltage to the electrostatic actuator, so that the electrostatic actuator mechanism may become a noise source of an imaging signal of a CCD imaging device arranged to face the objective lens. However, there is also a problem in terms of safety in the event of a leakage, and it is difficult to adopt the method. Further, in the above-described piezoelectric mechanism, since the displacement obtained by the piezoelectric element is small, the moving amount of the objective lens is also small, and it is difficult to obtain a desired zooming amount, particularly a large zooming amount.

On the other hand, since the above-mentioned wire mechanism mechanically moves the objective lens, it is not necessary to apply a high voltage as in an electrostatic actuator, and constitutes a zoom mechanism that is larger than a piezoelectric mechanism. It is possible. FIG. 5 shows an example of this wire mechanism. FIG. 3 is a diagram showing a cross-sectional configuration of the distal end portion of the objective optical system. The upper half shows an observation state at normal magnification, and the lower half shows an observation state at magnification. A distal end outer cylinder 31 and a distal end inner cylinder 32 provided at the distal end of an optical cylinder extending to an operation unit (not shown) are coaxially attached to the distal end surface of the outer cylinder 31 and the inner cylinder 32. Is provided with a cover glass 33 for sealing each opening. The objective lens 34 is provided inside the distal end inner tube 32 by a lens holding tube 35 and is movable in the optical axis direction. Further, a CCD image pickup device 36 is provided inside the distal end inner tube 32 at a position on the optical axis facing the objective lens 34 by a CCD holding tube 37, and is movable in the optical axis direction. A signal cable 38 is connected to the CCD imaging device 36, and is electrically connected to an operation unit (not shown). A cam ring 39 in which three cam grooves 39a to 39c are formed is fitted around the distal end inner cylinder 32, and the first and second cam grooves 3 among the cam grooves are provided.
9a and 39b respectively have the lens holding cylinder 35 and the CC.
The cam pins 35a protruding radially from the D holding cylinder 37,
37a is fitted. Further, the other third cam groove 39c extends along the optical cylinder, and its distal end is located in a gap defined between the distal outer cylinder 31 and the distal inner cylinder 32. Connected to the distal end of the operating cable 40,
A cam pin 41a provided on a cam body 41 movable in the direction in which the operation cable 40 extends, that is, in the optical axis direction, is fitted. In addition, compression springs 42 and 4 that can expand and contract in the optical axis direction are provided between the lens holding barrel 35 and the CCD holding barrel 37 and between the cam body 41 and the inner barrel 32, respectively.
3 is inserted.

In the conventional objective optical system, when the operation cable 40 is not operated, the cam body 41 connected to the operation cable 40 is moved to the distal end side by the extension force of the spring 43 as shown in the upper half of FIG. And the cam ring 39 is in the corresponding rotational position. Thereby, the lens holding barrel 35 and the CCD holding barrel 37 are connected to the cam ring 39.
Is located at the optical axis position determined by the first and second grooves 39a and 39b. At this time, the objective lens 34
And the CCD image sensor 36 are located close to each other, and the imaging magnification of the subject is set low. On the other hand, the operation cable 40
5 is moved rightward in FIG. 5, the cam body 41 is moved rightward while bending the spring 43 as shown in the lower half of FIG. 5, and the cam ring 41 is moved according to the shape of the third cam groove 39c. Rotate 39. Thereby, the lens holding cylinder 3
5 and the CCD holding tube 37 are moved in the optical axis direction according to the shapes of the first and second cam grooves 39a and 39b of the cam ring 39, the distance between the objective lens 34 and the CCD image pickup device 36 is enlarged, and the imaging magnification of the subject is increased. To a high state.

[0005]

In such a conventional wire mechanism, by operating the operation wire, the objective lens can be moved in the direction of the optical axis to achieve zooming in the objective optical system. As described above, the noise with respect to the image pickup signal of the CCD image pickup device can be prevented, the moving distance of the objective lens can be set large, and it is possible to cope with the required zooming. However, in order to realize the movement of the objective lens, the number of components for configuring the objective optical system, such as a cam ring, a cam body, an operation cable, and a spring, is inevitably increased, and the structure becomes complicated. At the same time, there is a problem that it is difficult to reduce the size. Also, the rotation of the cam ring during zooming causes sliding between the cam body and the cam pin and the cam groove of the cam ring, so that abrasion powder is generated, and the abrasion powder is generated on the lens surface of the objective lens and the CCD image pickup device. There is a problem that it adheres to the image pickup surface and causes an obstacle to image pickup, frequent cleaning is required, and maintenance becomes troublesome. Furthermore, when the scope containing the objective optical system is bent, the operation cable may be bent integrally and the objective optical system may be changed in magnification unexpectedly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnifying endoscope capable of reducing the number of constituent parts to achieve simplification and downsizing of the configuration, and solving the above-mentioned problems occurring in the conventional configuration. To provide.

[0007]

SUMMARY OF THE INVENTION According to the present invention, at least one of an objective lens and an image pickup element provided in an optical tube of an objective optical system of an endoscope is moved in an optical axis direction to change an image pickup magnification. In the configured magnifying endoscope, at least one of the objective lens and the imaging element is sandwiched by at least two springs arranged to face each other in the optical axis direction, and one of the at least two springs changes in temperature. It is characterized by comprising means for changing the temperature of the one spring, which is made of a material whose spring coefficient is changed accordingly. For example, the objective lens and the image sensor are each configured to be movable in an optical axis direction, a first spring is interposed between the objective lens and a tip side portion of the optical cylinder, and the image sensor and the optical A second spring is interposed between the rear end portion of the cylinder and
A third spring is interposed between the objective lens and the imaging device, and the first and second springs are each formed of a material whose spring coefficient changes with a change in temperature.

Here, the material whose spring coefficient is changed in accordance with the temperature change is formed of a shape memory alloy, and the means for changing the temperature of the spring is formed as a wiring structure for passing a current through the shape memory alloy. The temperature of the spring is increased by utilizing self-heating when the shape memory alloy is energized. Further, the material whose spring coefficient is changed in accordance with the temperature change is such that the spring coefficient at the transformation temperature or lower is smaller than the spring coefficient of the other spring, and the spring coefficient at a temperature higher than the transformation temperature is the other spring. It is made of a material that has a larger spring coefficient. For example, in the shape memory alloys constituting the first and second springs, the spring coefficient at a temperature lower than a predetermined temperature is lower than the spring coefficient of the third spring and higher than the predetermined temperature. Are made of a material whose spring coefficient is larger than the spring coefficient of the third spring.

As described above, by controlling the temperature of one of the springs and changing its spring coefficient, the magnitude relation of the spring coefficient with the other spring is reversed, and these springs are sandwiched in the optical axis direction. The objective lens and the image sensor are moved in the optical axis direction, the distance between the objective lens and the image sensor in the optical axis direction is changed, and the image pickup magnification of the image sensor by the objective lens is changed.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of an endoscope to which the present invention is applied. An insertion section 2 is extended from an operation section 1 for performing various operations, and a distal end portion of the insertion section 2 is configured as a curved section 2a, and an objective optical system 3 is provided inside the curved section 2a. In addition, a light source unit 4 that supplies illumination light for illuminating an object to be observed by the objective optical system 3 through the operation unit 1 is connected to the operation unit 1 via a light guide 5. FIG. 2 shows the bending portion 2 of the insertion portion 2.
FIG. 3 is a partially exploded perspective view of an objective optical system housed in a, and FIG. 3 is an enlarged sectional view of an assembled state thereof. Note that FIG.
Indicates the state during normal observation. A distal end outer tube 12 and a distal end inner tube 13 are coaxially attached to a distal end portion of an optical tube 11 embedded in the curved portion 2a. A cover glass 15 is attached to the opened opening 14 to seal the inside of each of the tubes 12 and 13. Although the cover glass 15 may be made of flat glass, it is formed as a concave lens here in order to increase the magnification in the objective optical system. An objective lens 17 supported by a lens holding barrel 16 is supported inside the distal end inner cylinder 13 so as to be movable in the optical axis direction along the inner surface of the distal end inner cylinder 13 at a position facing the cover glass 15. Have been. Further, the distal end inner cylinder 1 is provided at a required distance from the objective lens 17 in the optical axis direction.
Inside 3, a CDD image pickup device 19 supported by a CCD holding tube 18 is supported inside so as to be movable in the optical axis direction along the inner surface of the distal end inner tube 13. The CCD imaging device 1
9 is connected to a signal cable 20 that is inserted through the insertion section 2 and extends to the operation section 1.

Here, the lens holding barrel 16 has a holding part 161 holding the objective lens 17 and a sliding contact part 1 having a diameter larger than that of the holding part 161 and slidingly contacting the inner surface of the distal end inner barrel 13.
A step portion 163 in the radial direction is provided between the first and second springs 62 and 62. The outer surface and the inner surface of the step portion 163 in the cylinder axis direction serve as spring seats to which a first spring 22 and a third spring 24 described later are locked. It is configured. In addition, C
The CD holding cylinder 18 has projections 181 projecting radially at a plurality of positions in the circumferential direction of the outer peripheral surface thereof, here two positions, and these projections 181 correspond to two corresponding positions in the circumferential direction of the tip inner cylinder 13. Are inserted radially into guide grooves 131 formed to have a required length in the optical axis direction.
The distal end of 1 protrudes from the outer peripheral surface of the distal end inner cylinder 13,
It is located in an annular space 111 defined between the optical cylinder 11 and the distal end inner cylinder 13. The CCD
The rear end of the holding cylinder 18, that is, the end opposite to the objective lens 17 is formed to have a somewhat large diameter, and a seal ring 21 is fitted and supported on the outer peripheral surface thereof. And the sealing property between them.

A first spring 2 formed in a coil shape is provided around the holding portion of the lens holding barrel 16.
2 are loosely inserted, and both ends thereof are engaged with the distal end surface of the distal end inner cylinder 13 and the outer surface of the step portion 163, respectively. A second spring 23 formed in a coil shape is provided in an annular space 111 between the distal end inner cylinder 13 and the optical cylinder 11, and both ends of the second spring 23 are provided in the CCD holding cylinder 18. Protrusion 181 and the distal end inner cylinder 13
Are respectively locked to the flange 132 at the rear end.
Further, a third spring 24 formed in a coil shape is provided inside the sliding contact portion 162 of the lens holding barrel 16, and both ends of the third spring 24 are connected to the inner surface of the step portion 163 and the CCD.
Each of the holding cylinders 18 is locked to the distal end surface.

Here, the first spring 22 and the second spring
The spring 23 is formed as a so-called tension spring, which always has an elastic force in the contraction direction, using a material whose spring coefficient is changed by temperature, in this case, a metal shape memory alloy. As this kind of shape memory alloy,
For example, Ti-Ni alloy, Ti-Ni-Cr alloy, Au
-Cd alloy, Cu-Ni-Al alloy, Cu-Zn-Al
Alloys are applicable. These shape memory alloys have a small spring coefficient at room temperature, and have a characteristic that the spring coefficient increases approximately three times when the temperature exceeds the transformation temperature and the temperature rises. Although not shown, the first spring 22 and the second spring 23 are electrically connected to the operation unit 1 by a wiring cord extending along the optical cylinder 11. The operation of the operation section 1 allows a minute current to flow through the first spring 22 and the second spring 23 at a desired timing. Also, the third spring 24
Is also configured as a tension spring having an elastic force in the always shortening direction.
Is formed of an ordinary elastic material having a spring property, and its spring coefficient at normal temperature is equal to the first and second springs 2.
First and second springs 22 and 23 at a temperature higher than the transformation temperature and higher than the transformation temperature
An elastic material having a value smaller than the spring coefficient is used.

According to the objective optical system having this configuration, the first
When the first and second springs 22 and 23 are not energized, that is, when the first and second springs 22 and 23 are at room temperature, the spring coefficient of the third spring 24 is the first and second springs. 2 each spring 22,2
3, the third spring 24 is in a shortened state due to its tensile force, while the first and second springs 2 are in a state as shown in FIG.
Each of the springs 2 and 23 is extended by losing the tensile force of the third spring 24, so that the spring forces of these springs are balanced with each other. In this state, the third spring 24
, The lens holding tube 16 and the CCD holding tube 18, that is, the objective lens 17 and the CCD imaging device 19 are brought close to each other, the optical axis length of the objective lens 17 with respect to the CCD imaging device 19 is shortened, and L1 It becomes a state of dimensions. As a result, the objective lens 17
The imaging magnification of the subject formed on the D imaging device 19 is such that the optical axis length between the cover glass 15 and the objective lens 17 is longer than the optical axis length between the objective lens 17 and the CCD imaging device 19. Then, the normal magnification is set in advance in a state where the subject at a predetermined distance in front of the cover glass 15 is in focus.

On the other hand, when a minute current is applied to the first and second springs 22 and 23 through a wiring cord (not shown), both springs 22 and 23 generate heat due to the electric resistance of the springs 22 and 23 and the second springs 22 and 23 generate heat. The temperature of each of the first and second springs 22 and 23 is increased. When the first and second springs 22 and 23 exceed the transformation temperature due to the temperature rise, the first and second springs 2 and 23
The spring coefficients of the second spring 23 and the second spring 23 are increased.
Larger than the spring coefficient of As a result, as shown in FIG. 4, the first and second springs 22 and 23 are shortened while extending the third spring 24 by their respective tensile forces. As a result, the lens holding cylinder 16 and the CC
The D holding cylinder 18, that is, the objective lens 17 and the CCD imaging device 19 are separated from each other in the optical axis direction, the optical axis length between them is lengthened, and the optical axis length becomes L2 (L2> L1). As a result, the imaging magnification of the object formed on the CCD image pickup device 19 by the objective lens 17 is such that the optical axis length between the cover glass 15 and the objective lens 17 is smaller than that of the objective lens 17.
Is shorter than the optical axis length between the CCD image sensor 19 and the CCD imaging device 19, the magnification becomes higher than the normal magnification in a state where the subject at a predetermined distance in front of the cover glass 15 is focused, and Imaging in an enlarged state at the element 19 becomes possible.

The first and second springs 22, 2
3 is stopped, the springs 22 and 2 are turned off.
3, the temperature of each of the springs 22 and 23 is reduced by natural cooling. When the temperature becomes lower than the transformation temperature, the spring coefficients of the first and second springs 22 and 23 are again increased. Since the spring coefficient is smaller than the spring coefficient of the third spring 24, the state is returned to the state shown in FIG. 3, and observation and imaging at a normal magnification become possible.

Table 1 shows the specifications of the first to third springs in the objective optical system actually manufactured by the inventor. Here, the transformation temperature is 55 to 65 ° C., and the current flowing through the first and second springs is about 3 A.

[0018]

[Table 1]

As described above, in the objective optical system of this embodiment, the magnification of the image pickup in the objective optical system is set to the normal magnification only by turning on and off the energization of the first and second springs 22 and 23. It is possible to change the magnification. In order to realize this zooming, first to third springs 22 to 24 are provided inside the objective optical system,
Since it is only necessary to adopt a structure in which a current supply wiring cord is connected to the first and second springs 22 and 23, the number of parts constituting the objective optical system is small, and the structure is simple and compact. It becomes possible. Further, since sliding parts such as a cam ring and a cam are not required, the sliding parts are reduced as a whole, and dirt due to abrasion powder hardly occurs, which is advantageous in terms of maintenance. Further, since wires required by the wire mechanism are unnecessary, zooming failure due to bending of the wires does not occur, zooming is stably maintained, and the reliability of the objective optical system is improved.

Here, in the above embodiment, the first and second
Are formed of a shape memory alloy, the third spring 24 is formed of a shape memory alloy,
The first and second springs 22 and 23 can be formed of a normal spring material. In this case, at normal temperature, the spring coefficient of the third spring 24 becomes smaller than the spring coefficients of the first and second springs 22 and 23, so that the distance between the objective lens 17 and the CCD image sensor 19 becomes smaller, When the third spring 24 is heated to increase the spring coefficient, the first and second springs 22 and 23
The first to third springs 22 to 24 are configured as so-called compression springs. Further, in the present invention, all of the first to third springs may be formed of a shape memory alloy as long as the relationship between the respective spring coefficients is satisfied.

In the above embodiment, the first to third
Objective lens 17 and CCD by springs 22 to 24
Although the configuration example in which the imaging device 19 is sandwiched in the optical axis direction is shown, only one of the objective lens 17 and the CCD imaging device 19 is provided.
For example, only the objective lens 17 may be sandwiched in the optical axis direction by a pair of springs, and the objective lens may be moved along the optical axis with respect to the CCD imaging device fixed and supported in the optical cylinder. In this case, one of the pair of springs may be made of a shape memory alloy.

The shape memory alloy for forming the spring, which is a component of the present invention, is not necessarily made of metal, but can be made of a shape memory resin. However, in this case, a heater for heating the shape memory resin may be provided along a spring formed of each shape memory resin, and the heater may be energized by a wiring code.

[0023]

As described above, the present invention is based on at least two springs in which at least one of the objective lens and the image pickup device housed in the optical cylinder of the objective optical system of the endoscope is arranged facing the optical axis direction. One of the two springs is formed of a material whose spring coefficient is changed with a change in temperature, and means for changing the temperature of the one spring is provided. By controlling the temperature and changing the spring coefficient, it is possible to invert the magnitude relationship of the spring coefficient with the other spring, and the objective lens and the image pickup element sandwiched in the optical axis direction by the pair of springs. At least one is moved in the direction of the optical axis to change the distance between the objective lens and the image sensor in the direction of the optical axis. It is possible to vary the imaging magnification at. Therefore, the number of components can be reduced as compared with the conventional wire mechanism, and the structure can be simplified and the size can be reduced. Further, since the number of sliding portions is reduced, dirt due to abrasion powder and poor magnification due to wire bending do not occur, and a maintenance-free and highly reliable magnifying endoscope can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a magnifying endoscope to which the present invention is applied.

FIG. 2 is a partially exploded perspective view of the objective optical system according to the present invention.

FIG. 3 is a sectional view of the objective optical system according to the present invention in a normal observation state.

FIG. 4 is a cross-sectional view of the objective optical system according to the present invention in an enlarged observation state.

FIG. 5 is a sectional view of an example of an objective optical system of a conventional magnifying endoscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation part 2 Insertion part 3 Objective optical system 4 Light source part 5 Light guide 11 Optical cylinder 12 Tip outer cylinder 13 Tip inner cylinder 15 Cover glass 16 Lens holding cylinder 17 Objective lens 18 CCD holding cylinder 19 CCD image sensor 20 Signal cable 22 1 spring 23 2nd spring 24 3rd spring

Claims (6)

[Claims] An objective lens and an image pickup element are provided in an optical cylinder of an objective optical system of an endoscope, and at least one of the objective lens and the image pickup element is moved in an optical axis direction to change an image pickup magnification. In the magnifying endoscope configured so that at least one of the objective lens and the imaging element is sandwiched by at least two springs arranged to face each other in the optical axis direction, and one of the at least two springs has a temperature. An endoscope made of a material whose spring coefficient is changed in accordance with the change, and comprising means for changing the temperature of the one spring. 2. The optical system according to claim 1, wherein the objective lens and the image pickup device are arranged so as to be movable in an optical axis direction, and a first spring is interposed between the objective lens and a distal end portion of the optical cylinder. A second spring is inserted between the image sensor and the rear end portion of the optical cylinder, a third spring is inserted between the objective lens and the image sensor,
2. The magnifying endoscope according to claim 1, wherein the second spring and the second spring are each formed of a material whose spring coefficient changes with the temperature change. 3. The material whose spring coefficient is changed with a change in temperature is made of a shape memory alloy, and the means for changing the temperature of the spring is formed as a wiring structure for passing a current through the shape memory alloy. 3. The magnifying endoscope according to claim 1, wherein the temperature of the spring is increased by utilizing self-heating when the shape memory alloy is energized. 4. 4. The material whose spring coefficient is changed according to the temperature change, wherein a spring coefficient at one temperature is smaller than a spring coefficient of the another spring at the one temperature,
The magnifying endoscope according to claim 1, wherein the magnifying endoscope is formed of a material in which a spring coefficient at another temperature different from the one temperature is larger than a spring coefficient of the other spring at the one temperature. 5. The material whose spring coefficient is changed according to the temperature change, wherein a spring coefficient at a transformation temperature or lower is smaller than a spring coefficient of the another spring at or below the transformation temperature,
4. A shape memory alloy in which a spring coefficient at a temperature higher than the transformation temperature is larger than a spring coefficient of the other spring at a temperature higher than the transformation temperature.
2. The magnifying endoscope according to 1. 6. The shape memory alloy forming the first and second springs, wherein a spring coefficient at a temperature lower than a predetermined temperature is smaller than a spring coefficient of the third spring and is lower than the predetermined temperature. 4. The magnifying endoscope according to claim 2, wherein the magnifying endoscope is made of a material having a higher spring coefficient at a higher temperature than a spring coefficient of the third spring.