JPH08136832A - Autofocusing mechanism for endoscope - Google Patents

Abstract

PURPOSE: To provide an autofocusing mechanism for endoscope capable of obtaining a sufficient observational image without out-of-focus even when a celom wall is pulsated under the condition that the tip part of an endoscope is located at the boundary point of adjacent focusing zones. CONSTITUTION: In an autofocusing mechanism for endoscope performing autofocusing operation by measuring a distance from the tip of an endoscope to a part to be observed and moving an objective optical system in accordance with the measured value, this mechanism is provided with a measuring means for measuring a distance between the tip of the endoscope and a celom wall, an objective optical system having plural focusing zones A-D whose focal distances are mutually different and mutually overlapping adjacent focusing zones among these focusing zones A-D, a moving means for objective optical system for moving the objective optical system in the focusing zones A-D based on the measured value information from the measuring means and a setting means for setting the overlapping amount between the focusing zones A-D larger than the pulsating amplitude of the celom wall based on the measured value information from the measuring means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus mechanism provided in an objective optical system of an endoscope.

[0002]

2. Description of the Related Art In a general-purpose autofocus program for a still camera or a video camera, since the subject is usually a static body such as a person or a landscape, the lens is moved so that the measured distance is in focus and the focus is adjusted. Auto focus is possible. In addition, when the subject is only approaching or moving away, the focus can be adjusted.

[0003]

When observing the inside of a body cavity with an endoscope using such an autofocus system, since the wall of the body cavity is constantly pulsating, AF is performed after distance measurement.
There was a problem that the wall of the body cavity moved during a short time when the lens was moved, and eventually the focus became out of focus. Further, in this case, if an attempt is made to focus on the pulsating body cavity wall, the focus mechanism will always operate, and there is a problem that the durability of the autofocus mechanism deteriorates.

For this reason, a zone focus system is conceivable in which the focus is adjusted at a large pitch rather than the focus at a fine pitch. In other words, this zone focus method does not drive the focus mechanism every time the distance between the tip of the endoscope and the body cavity wall changes, but within a certain range considering the depth of focus (depth of field). The focus control is performed stepwise.

Specifically, the assumed distance between the tip of the endoscope and the wall of the body cavity is divided into several ranges (zones) in advance, and the focal length is changed for each divided zone. To do so, the AF lens is moved to a predetermined position.
Therefore, each zone has a fixed focal length determined by the position of the AF lens. Further, each zone is set within a distance range substantially equal to the depth of focus corresponding to the fixed focal length. Therefore, even if the distance between the tip of the endoscope and the wall of the body cavity changes within each zone, it is possible to observe within the range of the depth of focus of that zone, so that the observation image can be observed without moving the AF lens. Never fall into the impossible. That is, it is not necessary to move the AF lens each time the distance between the tip of the endoscope and the body cavity wall changes, and a sufficient observation image can be obtained by moving the AF lens for each zone.

[0006] As described above, a plurality of focusing ranges (hereinafter referred to as "focusing points") obtained by dividing the distance between the tip of the endoscope and the body cavity wall (hereinafter referred to as "observation distance") into several zones Zone) is set in advance and the AF lens is moved stepwise by a constant distance width as the focusing zone changes according to the movement of the endoscope. Even if the observation distance is changed due to the pulsation of the body cavity wall under observation in, observation can be performed within the range of the depth of focus, so the observation image does not fall even without constantly moving the AF lens. Since it is not necessary to move the AF lens every time the distance changes, abrupt deterioration of the focus mechanism can be prevented.

However, in such a zone focus system, there is a movement of the body cavity wall due to pulsation with the tip of the endoscope positioned at a change point for changing the focus zone, that is, a boundary point between adjacent focus zones. , And the focusing zone corresponding to the observation distance before pulsation and the focusing zone corresponding to the observation distance after pulsation are different, focus control cannot follow this well, and the body cavity wall deviates from the focusing range. There was a drawback that the observation image fell in love with it. That is, if the body cavity wall pulsates at the boundary points between the focus zones, the observation distance will change across the two focus zones during a short time after the distance is measured and the AF lens is moved, and this is not suitable. There is a drawback that the focus control in the focusing zone is not performed and the focus is lost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to pulsate a body cavity wall in a state in which a tip portion of an endoscope is positioned at a boundary point between adjacent focusing zones. Even if it is, it aims at providing the autofocus mechanism for endoscopes which can obtain a sufficient observation image without a love.

[0009]

In order to solve the above-mentioned problems, the present invention measures the distance from the tip of an endoscope to an observed part and moves an objective optical system according to the measured value. In an autofocus mechanism for an endoscope that performs automatic focusing, a measuring unit that measures a distance between a distal end of the endoscope and a body cavity wall and a plurality of focusing zones having different focal lengths are provided. An objective optical system in which adjacent focusing zones of the focusing zones overlap each other, and an objective optical system moving means for moving the objective optical system between the focusing zones based on measurement value information from the measuring means. Setting means for setting the overlap amount of the focusing zones larger than the pulsation amplitude of the body cavity wall based on the measurement value information from the measuring means.

[0010]

According to the above construction, since the respective focus zones overlap with each other, the observation distance changes due to pulsation of the body cavity wall or movement of the endoscope under observation in each focus zone. However, since the observation can be performed within the range of the focusing zone, the observation image is not affected even if the objective optical system is not constantly moved.

Further, since the overlapping amount of the focusing zones is set to be larger than the pulsation amplitude of the body cavity wall,
Even if the endoscope stops near the boundary area (overlap area) of the focusing zone and the body cavity wall pulsates, the pulsation does not affect the observed image.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which the body cavity wall 6 and the endoscope 1 face each other. As shown in the figure, the objective optical system provided in the distal end portion of the endoscope 1 includes an objective lens group 2 and an AF lens which is arranged in the middle of the objective lens group 2 and is movable along the optical axis of the objective lens group 2. 3 and a solid-state image pickup device 5 provided as an image transmitting means provided behind the objective lens group 2. The AF lens 3 is attached to the rotating shaft of the motor 4 via a trapezoidal screw, and by driving the motor 4, the AF lens 3 can be moved back and forth. In addition to the solid-state imaging device 5, for example, an optical fiber can be used as the image transmitting means.

Further, the endoscope 1 is provided in the distal end portion of the endoscope 1.
An observation distance measuring means is provided for measuring the distance between the tip 1a and the body cavity wall 6. This observation distance measuring means,
For example, it is composed of an LED 7 as a light emitting element and a PSD 8 as a light receiving element. The LED 7 and the PSD 8 are arranged behind a cover glass 9 embedded in the tip surface of the endoscope 1, respectively. Note that the method of measuring the observation distance is not limited to the method using the LED 7 or PSD 8 as described above, and may be, for example, an optical measuring method, an ultrasonic measuring method, or an infrared measuring method.

The endoscope 1 includes an illumination lens group 10 for illuminating the body cavity wall 6 and a light guide fiber 1.
1 and 1 are provided. In addition, the motor 4, the solid-state imaging device 5, the LED 7, and the PSD 8 are connected to the wirings 13, 12, respectively.
It is connected to an automatic focus control device (not shown) via 15 and 14.

The automatic focus control device comprises an LED 7 and a PS.
The AF lens 3 is moved by driving the motor 4 based on the distance between the tip 1a of the endoscope 1 and the body cavity wall 6 (hereinafter referred to as the observation distance) measured by D8.
In this case, a plurality of focusing ranges (hereinafter referred to as focusing zones) A to D obtained by dividing the assumed observation distance into several zones are set in advance (FIG. 2).
), The automatic focus control device adjusts the AF lens 3 according to the change of the focusing zone according to the movement of the endoscope 1.
Is moved in steps over a fixed distance. Further, each focusing zone A to D has a fixed focal length determined by the position of the AF lens 3, and each focusing zone A to D has a distance substantially equal to the depth of focus corresponding to the fixed focal length. It is set in the range.

That is, as shown in FIG. 2, the focusing zone A is set in a range where the observation distance is 3 to 15 mm, and when the observation distance enters the focusing zone A, the AF lens 3
Is moved to a predetermined position along the optical axis, and the focal length is changed. In this case, the focusing zone A has a distance range (3 to 15 m) approximately equal to the depth of focus corresponding to the fixed focal length.
m), the observation can be performed within the range of the depth of focus of the focus zone A (the set distance of the focus zone A) even if the observation distance changes under observation in the focus zone A. Therefore, the observed image will not fall into an unobservable state. Therefore, when the observation distance is within the focusing zone A, the AF lens 3 is not moved from the predetermined position.

Similarly, the focusing zone B is set in a range where the observation distance is 5 to 30 mm, the focusing zone C is set in a range where the observation distance is 20 to 60 mm, and the focusing zone D is observed. The distance is set to a range of 50 to 90 mm.

It is important to note here that, as can be seen from FIG. 2, the focusing zones A to D overlap each other at a distance of 10 mm, and a zone change point P is provided at the center of these overlapping ranges. That is the point. Then, a program is preliminarily programmed so that the focusing zone is changed at these zone change points P.

The overlap distance (10 mm) is shown in FIG.
It is determined based on the data shown in. That is, FIG.
Measures the distance between the tip of the endoscope and the wall of the body cavity at a specific time, and among the increase and decrease, a value that changes regularly and periodically based on the average pulse of human being, that is, the pulsation amplitude of the wave The overlap distance is a value larger than the amplitude α.

The zone change point P is located at the observation distance of 10 mm in the focusing zone A, at the observation distance of 10 mm and 25 mm in the focusing zone B, and at the observation distance of 25 mm and 55 mm in the focusing zone C. In the focusing zone D, they are provided at the observation distance of 55 mm.

With such a setting, for example, when the observation distance becomes 10 mm which is the zone change point, the focusing zone A is kept until then.
AF lens 3 located at the setting position of
It is moved to the setting position of. Such focus zone changing operation can be performed reversibly. That is, the AF lens 3 that has been located at the set position of the focus zone B is moved to the set position of the focus zone A when the zone change point reaches 10 mm. Similarly, in the AF lens 3, when the observation distance becomes 25 mm which is the zone change point,
It moves reversibly between the set position of the focus zone B and the set position of the focus zone C, and the observation distance is 55 m which is the zone change point.
At m, the focus zone C moves reversibly between the set position of the focus zone C and the set position of the focus zone D. Of course, this A
The operation of the F lens 3 is performed via the automatic focus control device.

In such a reversible operation, the automatic focus control device causes the zone change point P in the observation distance measurement.
If the object is recognized once at a specific time, the normal autofocus operation is performed as described above, but if the zone change point P is recognized twice or more within a specific time, A at the change point P of the overlapping part of the focusing zones
To prevent the F lens 3 from moving astray, it is set to one of the adjacent focusing zones, and the zone change is not performed until the zone change point P is no longer recognized within a certain specific time. Such a series of operations is shown in the flowchart of FIG. In the figure, a portion indicated by a broken line shows a normal autofocus operation, and a portion indicated by a one-dot chain line shows a stray prevention operation.

According to the configuration described above, the LEDs 7 and P
The observation distance observed by SD8 and the zone change point P
At this stage, the automatic focus control device moves the AF lens 3 to a predetermined focus zone setting position, so that the focus is continuously achieved, and even if the endoscope 1 stops near the zone change point P. If, for example, the front focusing tendency, that is, the focus zone closer to the focus zone A is set, there is an overlap range larger than the pulsation amplitude α around the change point P.
The pulsation of the body cavity wall 6 does not affect the observed image, and the AF lens 3 does not stray. In the case of the opposite setting to the rear pin side, the AF lens 3 may be moved to the rear pin side.

In the above construction, the set distance (width) of the focusing zone may be changed based on the data obtained from the measurement value of the observation distance measuring means. The set distances of the focus zones may be the same or different between the focus zones. For example, the set distance (focusing range) of the focusing zone is widened at a long distance, and the focusing range is narrowed at a short distance. This is more suitable for observation and diagnosis. Further, the set number of focusing zones may be changed based on the data obtained from the measurement value of the observation distance measuring means.

FIG. 4 shows a modification of the method of setting the focus zone. As shown, the focusing zones A to
In D, the pulsation amplitude of the body cavity wall 6 is overlapped around the change point P, but the focusing zones D to F at long distances are overlapped.
In, the overlap is made without considering the pulsation amplitude. Further, as shown in the figure, the overlap amount between the focusing zones is not constant, and further, the overlap amount is small in the long distance and large in the short distance.

According to this structure, since the pulsation amplitude does not overlap at a long distance where the movement of the body cavity wall 6 due to the pulsation does not greatly affect the observation, the optical design and the program are simplified accordingly. . In addition, the focal zones at short distances are divided more finely, making it easy to observe.

Next, an endoscope equipped with an automatic insertion mechanism for automatically inserting the insertion portion into the body will be described. 2. Description of the Related Art Conventionally, there has been widely used an endoscopic device that has an advancing / retreating mechanism for advancing / retreating an insertion part, and by this advancing / retreating mechanism, the insertion part is automatically inserted into a body cavity or the like to observe a test site and perform various treatments. It is used. Some of these endoscopic devices include
Some are capable of switching between the automatic insertion state and the manual insertion state. For example, the one disclosed in JP-A-5-228102 is that. The device disclosed in this publication automatically controls the bending of the insertion portion when the insertion portion is inserted into the lumen.

However, in this device, switching between the automatic insertion state and the manual insertion state must be performed by operating the automatic / manual changeover switch provided in the control device or the like connected to the endoscope body. There was a problem that it was complicated.

Therefore, an apparatus having good operability that can easily switch from the automatic insertion state to the manual insertion state will be described below with reference to FIGS. 6 to 9. As shown in FIG. 6, this device includes an endoscope 27 having an insertion portion that is automatically inserted into the lumen of a living body. Endoscope 27
Has a bending drive unit 26 and a bending switch 21 for driving the insertion portion to bend. The bending switch 21 has, for example, a shape as shown in FIG. 9A, and is provided on an operation unit (not shown) of the endoscope 27. It is to be noted that the one having the same function as the bending switch 21 is shown in FIG.
A bending knob 40, a bending lever (bending stick) 42, and the like as shown in (b) of FIG.

The bending drive unit 26 and the bending switch 21 are respectively provided with an automatic insertion start switch 22 and the bending control unit 2 is provided.
4 is connected. Further, the lumen control unit 23 is connected to the bending control unit 24. Further, the manual bending operation start detection unit 25 is connected to the bending switch 21 and the bending control unit 24, respectively.

The bending drive unit 26 provided in the endoscope 27 includes a bending tube, an angle wire, a motor, etc., which are not shown, and is controlled by the bending control unit 24 so as to be in an arbitrary bending state. it can.

When the automatic insertion start switch 22 is operated,
The bending control unit 24 switches from the manual insertion control state to the automatic insertion control state. When the bending control unit 24 is in the manual insertion control state, when the operator operates the bending switch 21, the bending control is performed based on the change in the resistance value of the variable resistor (not shown) in the bending switch 21 that changes with the operation. Part 2
Reference numeral 4 controls the drive of the bending drive unit 26.

When the automatic insertion start switch 22 is operated to switch the bending control section 24 to the automatic insertion control state, the lumen detecting section 23 obtains a video output signal (not shown) from the endoscope 27 to set the center of the lumen. The bending control unit 24 performs drive control of the bending drive unit 26 based on the detection result. As a result, the distal end of the insertion portion of the endoscope 27 faces the center of the front lumen. In this automatic insertion operation, an advance / retreat mechanism unit that drives rollers that sandwich the insertion unit of the endoscope 27 to advance and retract the insert unit is provided, and the advance / retreat mechanism unit is linked with the bending control unit 24 to automatically insert Can be done.

When the bending switch 21 is operated by the operator, the manual bending operation start detector 25 detects the bending switch 2
A change in the resistance value of the variable resistor in 1 is detected and the signal is sent to the bending control unit 24. Then, the bending control unit 24 stops the automatic insertion control state based on the signal from the manual bending operation start detection unit 25, and switches to the manual insertion control state.

FIG. 7 shows the control of the bending drive section 26 during automatic insertion.
FIG. First, in step S1, the automatic insertion start switch 22 is operated to set the bending control section 24 to the automatic insertion control state. Next, in step S2, a signal for detecting the center of the lumen is sent from the lumen detecting section 23 to the bending control section 24, and the bending control section 24 controls the bending drive section 26 accordingly.

In step S3, the manual bending operation start detector 2
The presence or absence of a manual bending operation (operation of the bending switch 21) is detected by 5, and if there is no manual bending operation, the process returns to step S2. In this case, the insertion part of the endoscope 27 is repeatedly and automatically inserted by the advance / retreat mechanism part.

When the start of the manual bending operation is detected in step S3, the process proceeds to step S4, and the automatic insertion stop signal is sent from the manual bending operation start detecting section 25 to the bending control section 24. Then, in step S5, the automatic insertion is stopped, and the bending control unit 24 enters the manual insertion control state.

In the apparatus described above, when the bending switch 21 is operated during automatic insertion, the manual bending operation start detection unit 25 which is interlocked with this operation stops the automatic insertion control state of the bending control unit 24. When the insertion method is switched from automatic insertion to manual insertion, the operation performed immediately after that is often the operation of the bending switch 21 associated with the manual insertion. Therefore, according to this apparatus, since the automatic insertion control state is switched to the manual insertion control state only by operating the bending switch 21, and the manual operation can be directly performed, the automatic insertion start switch 22 The operability is improved because there is no need to operate.

A variation of such a device is shown in FIG. In the device according to this modification, the bending switch 21 is provided with a pressure-sensitive element such as pressure-sensitive rubber. This pressure-sensitive element is connected to the manual bending operation start detecting section 25.

In this configuration, when the operator touches the bending switch 21 during automatic insertion, the resistance value of the pressure sensitive element provided on the bending switch 21 changes, and the change is transmitted to the manual bending operation start detecting section 25. . When the manual bending operation start detection unit 25 detects a change in the resistance value when the bending switch 21 is operated by the operator, the manual bending operation start detection unit 25 sends the signal to the bending control unit 24. The bending control unit 24 switches from the automatic insertion control state to the manual insertion state based on the signal from the manual bending operation start detection unit 25.

The configurations described above provide various configurations shown in the following sections. 1. In the autofocus mechanism for an endoscope, which measures the distance from the tip of the endoscope to the observed part and moves the objective optical system according to the measured value to perform automatic focusing, the tip of the endoscope and the body cavity A measuring means for measuring the distance to the wall; an objective optical system having a plurality of focusing zones having different focal lengths, and adjacent focusing zones of the focusing zones overlapping each other; Objective optical system moving means for moving the objective optical system between the focusing zones based on the measurement value information from the measuring means, and the overlap amount of the focusing zones based on the measurement value information from the measuring means. Is set to be larger than the pulsation amplitude of the wall of the body cavity, the autofocus mechanism for an endoscope.

2. The autofocus mechanism for an endoscope according to item 1, wherein the focusing distance (zone width) of the focusing zones is not constant between the focusing zones. 3. The focusing distance (zone width) of the focusing zone is narrow in the focusing zone on the short distance side and wide in the focusing zone on the long distance side. mechanism.

4. The focusing distance (zone width) of the focusing zone can be changed based on the measurement value information from the measuring unit. Auto focus mechanism for mirrors.

5. The autofocus mechanism for an endoscope according to any one of items 1 to 4, wherein the number of the focusing zones can be changed based on the measurement value information from the measuring means.

According to the configurations described in the above items, better observation performance and diagnostic ability can be obtained. 6. The autofocus mechanism for an endoscope according to any one of items 1 to 5, wherein the overlapping amounts of the focusing zones are not constant between the focusing zones.

7. 7. The autofocus mechanism for an endoscope according to claim 6, wherein the overlapping amount of the focusing zones is large in the focusing zone on the short distance side and small in the focusing zone on the long distance side.

8. The setting means measures the distance between the endoscope tip and the body cavity wall at a specific time by the measuring means, and among the increase and decrease thereof, with reference to the average pulse of a human being,
The first and second aspects are characterized in that a wave that fluctuates regularly and periodically is calculated as a pulsation amplitude, and the focusing zones are overlapped by an amount larger than the pulsation amplitude obtained by the calculation. Item 8. The autofocus mechanism for an endoscope according to any one of items 7.

According to the configurations of the sixth to eighth items described above, the optical design and the program can be simplified. 9. When the distance between the tip of the endoscope and the wall of the body cavity is in the overlapping portion of two adjacent focusing zones, the objective optical system moving means moves the objective optical systems to be adjacent to each other for a specific time. The autofocus mechanism for an endoscope according to any one of items 1 to 8, wherein the autofocus mechanism is moved to one of the two focusing zones.

According to the construction of the ninth item, better observation performance and diagnostic ability can be obtained. 10. 10. The endoscope autofocus according to any one of items 1 to 9, wherein the measuring unit optically measures a distance between a tip of the endoscope and a wall of a body cavity. mechanism.

11. The endoscope autofocus according to any one of items 1 to 9, wherein the measuring unit measures the distance between the tip of the endoscope and the wall of the body cavity by ultrasonic waves. mechanism.

12. The autofocus mechanism for an endoscope according to any one of claims 1 to 9, wherein the measuring unit measures a distance between a tip of the endoscope and a wall of a body cavity by infrared rays. .

According to the constitutions of the tenth to twelfth items shown above, the responsiveness of the objective optical system moving means can be obtained without damaging the body cavity wall by the measurement by the measuring means. 13. A bending operation provided on an endoscope in an endoscope apparatus including two insertion means, an automatic insertion means for automatically inserting the insertion portion of the endoscope into the body and a manual insertion means for manually inserting the insertion portion into the body. Section, a manual insertion operation start detection means that interlocks with the bending operation part, and a stop means that stops the automatic insertion means in conjunction with the manual insertion operation start detection means. .

14. The endoscope apparatus according to Item 13, wherein the bending operation section is a bending knob. 15. The endoscope apparatus according to Item 13, wherein the bending operation section is a bending switch.

16. The endoscope apparatus according to Item 13, wherein the bending operation unit is a bending stick. 17． 17. The endoscope apparatus according to any one of items 13 to 16, wherein the manual insertion operation start detection means is a resistance value change detection means of a variable resistance that interlocks with a bending operation portion.

18. The manual insertion operation start detection means,
Item 17. The endoscope device according to any one of items 13 to 16, which is a resistance value change detection unit of a pressure sensitive element provided in the bending operation unit. 19. 19. The endoscope apparatus according to item 18, wherein the pressure sensitive element is piezoelectric rubber.

[0056]

As described above, according to the autofocus mechanism for an endoscope of the present invention, the wall of the body cavity pulsates with the tip of the endoscope positioned at the boundary point between adjacent focusing zones. Even if it is, it is possible to obtain a sufficient observation image without being enamored.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which an endoscope having an endoscope autofocus mechanism according to an embodiment of the present invention and a body cavity wall are in a body cavity.

FIG. 2 is a diagram showing a setting state of a focusing zone.

FIG. 3 is a graph showing measurement data for determining an overlap amount between focusing zones.

FIG. 4 is a diagram showing a modified example of a setting state of a focus zone.

FIG. 5 is a flowchart showing an operating state of the endoscope autofocus mechanism.

FIG. 6 is a block diagram of an endoscope apparatus with good operability that allows easy switching from an automatic insertion state to a manual insertion state.

7 is a flowchart showing control at the time of automatic insertion of the endoscope apparatus of FIG.

8 is a block diagram showing a modified example of the endoscope apparatus of FIG.

9 is a perspective view showing a bending switch of the endoscope apparatus of FIG. 6 and a modification example thereof.

[Explanation of symbols]

1 ... Endoscope, 2 ... Objective lens group (objective optical system), 3 ... A
F lens (objective optical system) 4 ... Motor (objective optical system moving means), 7 ... LED 7 (measuring means), 8 ... PSD (measuring means), A to D (F) ... Focusing zone.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

In such a reversible operation, the automatic focus control device causes the zone change point P in the observation distance measurement.
If it is recognized once within a specific time , the normal autofocus operation is performed as described above, but if the zone change point P is recognized more than once within a specific time, , One of the adjacent focusing zones is set so that the AF lens 3 does not stray at the change point P of the overlapping portions of the focusing zones, and the zones are set within a specific time. The zone is not changed until the change point P is no longer recognized. Such a series of operations is shown in the flowchart of FIG. In addition, in the part shown by the broken line in the figure shows the operation of normal autofocus,
The part shown by the alternate long and short dash line shows the operation for preventing stray.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

According to the configurations of the sixth to eighth items described above, the optical design and the program can be simplified. 9. The distance between the tip of the endoscope and the wall of the body cavity is adjacent 2
At a specific time in the overlapping part of the two focusing zones
The objective optical system moving means moves the objective optical system to either one of the two adjacent focusing zones when there is one in the range. The autofocus mechanism for an endoscope described in.

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G02B 7/28 G03B 13/36

Claims (1)

[Claims] 1. An autofocus mechanism for an endoscope, which measures a distance from a tip of an endoscope to a portion to be observed, and moves an objective optical system according to the measured value for automatic focusing. A measuring means for measuring the distance between the tip of the mirror and the wall of the body cavity, and an objective having a plurality of focusing zones having different focal lengths and adjacent focusing zones of these focusing zones overlap each other. An optical system, an objective optical system moving means for moving the objective optical system between the focusing zones based on measurement value information from the measuring means, and the focusing zone based on the measurement value information from the measuring means. An autofocus mechanism for an endoscope, comprising: setting means for setting an overlapping amount of the same to be larger than a pulsation amplitude of the body cavity wall.