JPH0522904Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention is an endoscope in which a lens barrel incorporating an objective lens system used to capture an image of an object to be observed is moved along the optical axis. This invention relates to a focus adjustment device for an endoscope that adjusts its focus by adjusting the focus of the endoscope.

[Prior Art] Endoscopes are used for medical purposes by being inserted into body cavities of the human body, etc., which cannot be seen directly, or into aircraft engines, nuclear reactors, etc., to perform observation, simple treatment, and repair. It is widely used in industrial and other fields.

The endoscope includes an insertion section that is inserted into the observation target, an operation section that is connected to the insertion section and that performs operations that are held by the user, and a universal cord that is connected to a light source device or the like. A light guide made of an optical fiber bundle is inserted between the universal cord and the operation part to the insertion part, and the illumination light sent through the light guide is irradiated toward the observation target part. The image of the observation target area is formed via an objective lens system onto the imaging plane of an image guide made of an optical fiber bundle similar to the above, or the imaging plane of an image sensor formed by a solid-state imaging device such as a CCD. It is composed of

Here, the objective lens system that forms the above-mentioned image of the observation target area on the imaging plane guides the lens barrel that supports the objective lens system so that the focal position can be adjusted. Fit into the ring,
The lens barrel is configured to be movable along its optical axis along the guide ring. The focus adjustment of the objective lens system by moving the lens barrel is performed by manipulating an adjustment member attached to the operation section with fingers.

The optical path in this objective lens system must be kept very precisely perpendicular to the image plane, and therefore the connection between the lens barrel and the guide ring must be made in such a way that there is no misalignment of the optical axis. In order to do this, strict dimensional relationships are established to prevent gaps from occurring between them.

[Problems to be solved by the invention] By the way, as mentioned above, in order to prevent the optical axis from shifting, if the lens barrel and the guide ring are brought into close contact with each other, the focus of the image of the object to be observed can be adjusted. Therefore, when the lens barrel is moved along the optical axis, the frictional resistance when sliding between the lens barrel and the guide ring increases, resulting in poor operability of the adjustment member. There was a drawback.

The present invention was devised to solve the problems of the prior art as described above, and its purpose is to smoothly move the lens barrel relative to the guide ring when adjusting the focus of the objective lens system. An object of the present invention is to provide a focus adjustment device for an endoscope that is capable of adjusting the focus of an endoscope.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a cylindrical extension part connected to the lens barrel incorporating the objective lens system, and the extension part is connected to the interior of the lens barrel. an image guide is inserted through the image guide, and is fitted into a guide ring having a plurality of V-shaped protrusions formed by one-character knurling along the entire circumference of the outer peripheral surface in the direction of movement of the lens barrel;
Focus adjustment is made possible by sliding the lens barrel on a guide ring in line contact, and a support member is provided on the guide ring in a non-rotatable manner, and an operating cable is connected to the lens barrel. The feature is that the operation cable is inserted through the support member, and the part between the support member and the lens barrel is inserted through a spring for positioning the lens barrel at a predetermined position. be.

[Operation] When moving the lens barrel along the guide ring in order to adjust the focus of the image of the observation target area,
Since the lens barrel and the guide ring are in line contact with each other through a V-shaped protrusion formed by knurling in the direction of movement, the contact area between the two is extremely small. As a result, the frictional force between the lens barrel and the guide ring during movement becomes extremely small, and the resistance during movement becomes small. Therefore, the resistance during movement of the lens barrel can be significantly reduced, and the operability of focus adjustment can be significantly improved.

Moreover, when the lens barrel is moved, it is necessary to prevent the optical axis from shifting, but the protrusion of the guide ring and the inner surface of the extension part of the lens barrel must slide directly, and as described above, Since the frictional resistance is reduced when the lens barrel moves, it can be tightly fitted to the guide ring, so there is no risk of the optical axis shifting or tilting. In addition, the objective lens system is usually adjusted in position in the rotational direction in consideration of aberrations, etc.
If the lens is displaced in the rotational direction during focus adjustment, problems such as increased aberrations may occur. However, since the operating cable for moving the lens barrel is inserted through a support member that cannot rotate relative to the guide ring, there is no risk that the lens barrel will be displaced in the direction of rotation when the lens barrel is moved. do not have.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 5 shows the overall configuration of an endoscope. In the figure, 1 indicates an insertion section into the observation target section, 2 indicates an operation section, and 3 indicates a universal cord. is connected to a light source device, and the illumination light sent from this light source device is transmitted via a universal cord 3 by a light guide 4 consisting of an optical fiber bundle extending from the operating section 2 to the tip of the insertion section 1. As shown in FIGS. 1 to 3, the object to be observed can be illuminated from the distal end surface of the insertion section 1.

The above-mentioned image of the object to be observed is sent through the insertion section 1 to the eyepiece section 6 connected to the operation section 2 by an image guide 5 made of an optical fiber bundle similar to the light guide 4. ing. In order to form an image of the observation target on the imaging plane of the image guide 5, an objective lens system 7 consisting of a plurality of lenses is mounted on the lens barrel 8 at the tip side of the image guide 5. It is installed in a supported state. In order to enable focus adjustment in the objective lens system 7, the objective lens system 7 is movable along its optical axis in the direction toward and away from the end surface of the image guide 5, which is the imaging surface. In order to support the lens barrel 8 so as to be movable in this direction, the lens barrel 8 is provided with an extending portion 8a connected to the proximal end thereof. The extending portion 8a is made of a cylindrical member having a predetermined thickness, and is fitted into a guide ring 9 that is attached to fix the image guide 5 to the insertion portion 1.

In order to move the above-mentioned lens barrel 8 along the guide ring 9 in the optical axis direction, the control cable 1
0 is provided, and the control cable 1
The tip of the cable 10a is fixed to a mounting portion 11 that projects from the outer peripheral surface of the extending portion 8a of the lens barrel 8. The guide ring 9 has a support portion 1.
2 is integrally provided, and the operation cable 10
The sleeve 10b is fixed to the support 12, and the cable 10a is passed through the support 12 and inserted into the sleeve 10b. A lens barrel 8 is provided between the mounting portion 11 and the support portion 12.
A spring 13 is loaded for fixing the image guide 5, and the spring 13 causes the lens barrel 8 to
It is biased in the direction away from the As a result, the objective lens system 7 becomes the closest state, and by pulling the cable 10a of the operation cable 10 and moving the lens barrel 8 in the direction against the spring 13, the focus is adjusted to the far side according to the amount of movement. will be done.

The other end of the operating cable 10 is extended to the operating section 2, and is connected to an adjustment disc 14 mounted on the operating section 2 via a rack-and-pinion mechanism, etc., as shown in FIG. By rotating the adjustment disc 14 with your fingers, the operation cable 1 can be adjusted.
The lens barrel 8 to which the tip of the lens 0 is attached can be moved along a guide ring 9. A friction plate (not shown) is connected to the adjustment disc 14, and this friction plate holds the adjustment disc 14 at a predetermined rotational position against the spring 13 acting on the cable 10a. This allows the lens barrel 8 to be fixed at a position where the focus of the objective lens system 7 is adjusted.

Here, as shown in FIG. 1, the outer circumferential surface of the guide ring 9 into which the extending portion 8a of the lens barrel 8 is fitted is knurled in the axial direction over the entire surface, and is knurled at predetermined pitch intervals. A large number of V-shaped protrusions 15, 15, 15, . They are configured to be connected in a line contact state along the optical axis of 7. On the other hand, the support member 12 has a protrusion 1 formed on the guide ring 9.
A V-shaped groove is formed to engage with 5. The operation cable 10 is connected to this support member 1.
2, so that when the lens barrel 8 is moved in the optical axis direction for focus adjustment, it is held so as not to be unnecessarily displaced in the rotational direction.

This embodiment is constructed as described above, and its operation will be explained next.

If the insertion section 1 of the endoscope is inserted into a body cavity or the like, the tip of the insertion section 1 is directed toward the observation target area, and the observation target area is illuminated with illumination light sent through the light guide 4, an image of the observation target area can be obtained. is transmitted by the image guide 5 to the eyepiece section 6 connected to the operation section 2. Therefore, by looking through the eyepiece 6, the object to be observed can be observed, and by attaching a camera to the eyepiece 6, an image of the object to be observed can be captured.

Here, the image of the observation target part is captured by the objective lens system 7.
In order to obtain a clear image, it is necessary to adjust the focal position as appropriate depending on the distance between the objective lens system 7 and the observation target. This focus adjustment can be performed by rotating the adjustment disk 14 provided on the operating section 2 with your fingers. Thus, the objective lens system 7 is normally held at the closest position by the biasing force of the spring 13 acting on the lens barrel 8. Therefore, when the adjustment disc 14 is rotated, the adjustment disc 1
Cable 10a of operation cable 10 connected to 4
is pulled, and the lens barrel 8 connected to the tip of the cable 10a moves in a direction approaching the image guide 5 against the spring 13, and the distance to the imaging plane changes depending on the amount of this movement. Therefore, focus adjustment can be performed. Since the friction plate is in contact with the adjustment disc 14, even if you release your finger from the adjustment disc 14 after performing the above-mentioned focus adjustment, the adjustment disc 14 remains in its rotational position. The lens barrel 8 is fixed at the position where the objective lens system 7 is focused.

In this way, although the lens barrel 8 is movable along the guide ring 9, the optical axis of the objective lens system 7 is always in a predetermined relationship with the incident end surface of the image guide 5. It is necessary to ensure that the axis center does not deviate from the center of the incident end surface of the image guide 5, nor is it tilted with respect to the optical axis and the incident end surface. For this reason, the inner diameter of the extending portion 8a of the lens barrel 8 and the tip of the protrusion 15 of the guide ring 9 are fitted together with almost no gap. As a result, there is no play between the two, and no deviation of the optical axis occurs. Moreover, since the extending portion 8a and the guide ring 9 are directly fitted, there is no possibility of misalignment between the objective lens system 7 and the image guide 5 due to assembly errors or the like.

Further, the position of the objective lens system 7 in the rotational direction is also set so that the aberration is minimized depending on the relative positional relationship with the entrance end surface of the image guide 5. Therefore, if the position of the objective lens system 7 in the rotational direction is also shifted, it is not preferable for observing the subject image.
However, since the support member 12 is reliably fixed in the rotational direction and the operating wire 10 is inserted through the support member 12, when a tensile force is applied to the operating wire 10, the The mounting portion 11 will surely follow the support member 12, and the lens barrel 8 will be accurately positioned in the rotational direction as well. That is, when performing focus adjustment, the objective lens system 7 moves accurately in the optical axis direction, and there is no possibility that the optical axis will shift or the objective lens system 7 will rotate.

However, the cable 10a and the lens barrel 8 are connected at a mounting portion 11 that is connected to the extending portion 8a of the lens barrel 8, so that the cable 10a and the lens barrel 8 are in a so-called cantilevered state.
For this reason, if the sliding resistance between the lens barrel 8 and the guide ring 9 is large, the smooth movement of the lens barrel 8 will be impaired, and the adjustment disk 14 may be rotated by hand. 8 may not move smoothly, and in extreme cases, the lens barrel 8 may not move smoothly.
It may become impossible to move the objective lens system 7, or uneven wear may occur during long-term use, causing the optical axis of the objective lens system 7 to shift.

However, since the lens barrel 8 and the guide ring 9 are brought into line contact by the protrusion 15,
The contact area between the two becomes significantly smaller, making it possible to significantly reduce sliding resistance. For this purpose, even if the difference between the inner diameter of the extending portion 8a of the lens barrel 8 and the outer diameter of the guide ring 9 is almost eliminated, the optical axis of the objective lens system 7 is prevented from shifting. In addition, even if the lens barrel 8 is driven in a cantilevered state, it can smoothly slide on the guide ring 9, and focus adjustment can be performed smoothly. . Moreover, if the lens barrel 8 can be slid smoothly in this manner, fine control can be performed, and the operability of focus adjustment can be significantly improved.

In addition, when performing focus adjustment using the adjustment disc 14 described above, the spring force of the spring 13 acting on the lens barrel 8 and the sliding resistance when the lens barrel 8 slides along the guide ring 9 are It is necessary to rotate the adjusting disc 14 against the total force of the friction force acting between the adjusting disc 14 and the friction plate. Here, lens barrel 8
If the sliding resistance between the guide ring 9 and the guide ring 9 is large,
The lens barrel 8 is moved against the image guide 5 against this sliding resistance.
It is necessary to increase the spring force of the spring 13 to separate the lens from the lens, and at the same time, increase the frictional force between the adjustment disc 14 and the friction plate to fix the lens barrel 8 at a predetermined focus adjustment position. It will stop happening. However, in the present invention, by reducing the sliding resistance between the extending portion 8a of the lens barrel 8 and the guide ring 9, the spring force of the spring 13 acting on the lens barrel 8 and this spring force are reduced. In order to fix the lens barrel 8 in a predetermined position against the The force can be made extremely small, and the focus adjustment operation can be performed extremely smoothly with a light operation force.

Moreover, as mentioned above, in order to reduce the sliding area when the lens barrel 8 slides, the outer surface of the guide ring 9 is configured to be knurled, making the machining extremely easy. Furthermore, since the lens barrel 8 is configured to adjust the focus by directly sliding against the guide ring 9 inserted through the image guide 5, the objective lens system 7 can be directly aligned with the image guide 5. The focus adjustment device can be assembled in a aligned state, and the position between the optical axis of the objective lens system 7 and the entrance end surface of the image guide 5 can be easily adjusted. It has a small number of points and can be made small and compact.

In the above-mentioned embodiments, a focus adjustment device used in a direct-viewing endoscope is shown, but it can also be configured as a focus adjustment device in a side-viewing endoscope. In addition, although the image of the observation target area was configured to be transmitted via an image guide, the image sensor of the observation target area is converted into an electrical signal and transmitted using an image sensor consisting of a solid-state image sensor such as a CCD. It can also be configured as a focus adjustment device for an endoscope of this type.

[Effects of the invention] As detailed above, the present invention reduces the sliding portion between the lens barrel and the guide ring when the lens barrel supporting the objective lens system slides along the guide ring. Since it is configured to have a line contact, the contact area between the two is extremely small, and focusing can be performed smoothly with a light operating force, resulting in extremely good operability in the endoscope. Being able to reduce the dynamic area means that the difference in diameter between the lens barrel and the guide ring can be made extremely small.
In order to eliminate the risk of misalignment of the optical axis due to play between the lenses and to move the lens barrel, the operating wire connected to the lens barrel is inserted through a support member that cannot rotate with respect to the guide ring. Therefore, even if the lens barrel is moved, it will not rotate, and the aberration characteristics of the objective lens system can be maintained in a stable state.Furthermore, in order to reduce the sliding resistance when moving the lens barrel, Since the projections are formed by knurling, this process is extremely easy to perform, and the lens barrel is configured to slide directly onto the guide ring through which the image guide is inserted. Therefore, the position of the image guide of the objective lens system relative to the incident end face can be smoothly adjusted, and the structure of the focus adjustment device can be simplified and compact, and the number of parts can be reduced.

[Brief explanation of drawings]

Fig. 1 is an external view of a focus adjustment device showing an embodiment of the present invention, Fig. 2 is a sectional view of Fig. 1, Fig. 3 is a sectional view of the tip of the endoscope, and Fig. 4 is a focus adjustment device. FIG. 5 is an explanatory diagram of the structure of the members, and is an external view of the endoscope. 1... Insertion section, 2... Operation section, 5... Image guide, 7... Objective lens system, 8... Lens barrel, 8a
...Extending portion, 9...Guide ring, 10...Operation cable, 14...Adjustment disc, 15...Protrusion.

Claims (1)

[Scope of utility model registration request] A cylindrical extension part is connected to the lens barrel incorporating the objective lens system, and the image guide is inserted into the extension part. Focus adjustment is made possible by fitting a plurality of protrusions into a guide ring formed in the direction of movement of the lens barrel and sliding the lens barrel in line contact with the guide ring. A support member is provided on the ring in a non-rotatable manner, an operating cable is connected to the lens barrel, the operating cable is inserted through the support member, and a portion between the support member and the lens barrel is connected to the lens barrel. 1. A focus adjustment device for an endoscope, characterized in that it is configured to be inserted through a spring for positioning at a predetermined position.