JPS6235090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an endoscope equipped with an objective lens focusing mechanism.

Generally, this type of endoscope has a slidable objective lens provided inside the distal end of its insertion portion, and its focus is adjusted by moving the objective lens.

However, conventional methods have the disadvantage that when focusing on a close object, the depth of field becomes shallow due to an optical physical phenomenon, making the observation range narrow and extremely difficult to observe.

Furthermore, when illuminating with the same amount of illumination light, the brightness of the observed image becomes too bright when observing from a short distance, harming the health of the operator's eyes, so it is troublesome to reduce the light amount of the light source each time.

Furthermore, when taking pictures with an endoscope, the light is illuminated with the same amount of light and the exposure time is automatically controlled to obtain a properly exposed picture, but when photographing a subject at a close distance, the subject becomes brighter, so the exposure time is shorter. Take a photo with On the other hand, since the exposure time is controlled by a mechanical shutter, a mechanical delay occurs, and this delay becomes an error exposure time. The closer the distance, the greater the ratio of the error exposure time to the proper exposure time.
There was a drawback that it was not possible to obtain photographs with proper exposure.

The present invention has been made focusing on the above circumstances,
The purpose of this is that by providing an aperture mechanism, the depth of field will not become shallow even when the objective lens is focused at a short distance, and there will be no need to reduce the light intensity of the light source. The present invention aims to provide an endoscope that reduces the ratio of error exposure time to proper exposure time during photographing.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 8. In the figure, reference numeral 1 denotes an operating section of an endoscope, and an insertion section 2, an eyepiece section 3, etc. are attached to this operating section 1. As shown in FIG. 2, a mounting bracket 4 is provided inside the tip of the insertion portion 2,
A cylindrical mounting frame 5 is provided inside this mounting bracket 4 . A lens frame 6 is slidably provided inside the mounting frame 5, and a pair of objective lenses 7 and 8 are disposed in the lens frame 6 so as to be spaced from each other and facing each other. Further, a protrusion 9 is provided on the outer wall of the lens frame 6, and the protrusion 9 is inserted through a slide hole 10 formed in the mounting frame 5 and protrudes to the outside. Further, a support portion 11 is provided protruding from the outer wall portion of the rear end of the mounting frame 5, and a first operating wire 12 is inserted through the inside of the support portion 11 using a closely wound coil pipe 13 as a guide pipe. . The tip of the first operating wire 12 is connected to the protrusion 9 of the mounting frame 6.

On the other hand, an aperture mechanism 14 is provided inside the installation fitting 4.
A pair of cylindrical variable aperture bodies 15, 15
is arranged to face the eyepiece lens 7. As shown in FIGS. 3, 5 and 7, pinions 16, 16 having a pitch circle diameter approximately equal to the diameter of the variable throttle bodies 15, 15 are attached to one end of these variable throttle bodies 15, 15. ing.
Further, the substantially central portion of the outer circumferential surface of the variable aperture bodies 15, 15 has a semicircular cross section along the circumferential direction, the center of the semicircle is on the circumference of the cylindrical outer circumferential surface, and the radius of the semicircle is Grooves 17, 17 are formed which increase approximately in proportion to the rotation angle of the variable aperture bodies 15, 15. The generating lines of the pair of variable throttle bodies 15, 15 are in contact with each other, and even when the pair of variable throttle bodies 15, 15 rotate while contacting each other without slipping, the two semicircular grooves 17, 17 always form a perfect circle, that is, a throttle hole 17a. It is arranged so that

Further, a rack 18 is engaged with the pinion 16 of the variable throttle body 15, and this rack 18 has a second
The operating wire 19 is connected. This second
By advancing and retracting the operating wire 19, the above-mentioned Rack 1
8 is operated, and as a result, the variable aperture body 1
5 and 15 are designed to be rotated. That is, when the rack 18 is moved forward and positioned at the forefront as shown in FIG. 4, the opening amount of the aperture hole 17a of the variable aperture bodies 15, 15 becomes the minimum as shown in FIG. 3, and the rack 18 is moved back. When the rack 18 is located at the middle part as shown in FIG. 6, the opening amount of the aperture hole 17a becomes middle as shown in FIG. 5, and when the rack 18 is further retreated and located at the rear end as shown in FIG. The opening amount of the aperture hole 17a is maximized as shown in FIG.

On the other hand, the first operating wire 12 and the second operating wire 19 are interlocked via an interlocking mechanism (not shown), so that when the first operating wire 12 advances or retreats, the second operating wire 19 is automatically advanced or retreated. It's getting old.

Further, an image guide fiber 20 is inserted into the rear end of the mounting frame 5 with its incident end face facing the objective lens 8. This image guide fiber 20 is formed by inserting an optical fiber bundle 21 into a pipe 22.
The observation image inside the body cavity is transmitted to the injection end surface.

23 is an objective cover lens attached to the mounting bracket 4.

Next, the operation of the above embodiment will be explained. First, when adjusting the focus of the objective lenses 7 and 8 to the short distance side, the first operation wire 12 is advanced. As a result, the objective lens frame 6 is slid forward, the objective lenses 7 and 8 are advanced, and the second operating wire 19 is automatically advanced via the interlocking mechanism, so that the rack 18 is pushed forward. As the rack 18 moves forward, the pinion 16,
When the variable aperture bodies 15, 15 are rotated through the aperture 16 and the rack 18 reaches the frontmost position as shown in FIG. 4, the opening amount of the aperture hole 17a becomes small as shown in FIG.

Also, when adjusting the focus to the far side, the first
The operation wire 12 is moved back. As a result, the objective lens frame 6 is slid rearward, the objective lenses 7 and 8 are retracted, and the second operating wire 19 is automatically retracted, so that the rack 18 is moved rearward. This movement of the rack 18 causes the variable aperture bodies 15, 15 to rotate via the pinions 16, 16, respectively, and when the rack 18 passes through the state shown in FIG. 6 and reaches the rearmost position as shown in FIG. 7th
As shown in the figure, the opening amount of the aperture hole 17a becomes large.

As described above, when the aperture mechanism 14 is provided and the focal length of the objective lenses 7 and 8 is adjusted to the short distance side, the aperture opening degree of the aperture mechanism 14 is made small.
Even when the focus is adjusted to a short distance, the depth of field does not become shallow, and there is no need to reduce the amount of light from the light source. Furthermore, there is no need to shorten the exposure time when taking a photograph, and the ratio of the error exposure time to the proper exposure time does not become large.

The depth of field when the focus is adjusted to each distance is shown in Figure 9, and the depth of field without an aperture mechanism is shown in Figure 10. Although the depth of field is the same when the focus is adjusted, the depth of field when the focus is adjusted to medium and short distances is significantly increased with the aperture mechanism 14.

Note that the present invention is not limited to the above-mentioned embodiment, and the aperture mechanism 30 may be configured as shown in FIG. 11. That is, as shown in FIG. 12, this diaphragm mechanism 30 is made up of a pair of S-shaped diaphragm blades 31, 31 which are overlapped and whose midway portion is rotatably supported by a pin 32. An opening, that is, an aperture 33 is formed by the upper side of the blades 31, 31. Further, a tension spring 34 is installed between the lower ends of the aperture blades 31, 31, and this tension spring 34 causes the aperture blades 31, 3
The lower sides of 1 are biased toward each other.

Further, a taper pin 35 is inserted between the lower portions of the aperture blades 33, 33, and an operating wire 36 is connected to the end of the taper pin 35. By moving the operation wire 36 back and forth, the taper pin 35
is moved back and forth, thereby adjusting the opening amount of the aperture 33.

Thus, when adjusting the focus of the objective lenses 7 and 8 toward the short distance side, the first operating wire 12 is advanced. By advancing this first operating wire 12,
The objective lens frame 6 is slid forward and the objective lenses 7 and 8 are advanced, and at this time the operating wire 36 is automatically advanced, as shown in FIGS. 12 and 13.
As shown in the figure, the taper pin 35 is moved forward. As a result, the pair of aperture blades 33 are rotated by a predetermined amount so that their upper sides approach each other, and the opening amount of the aperture opening 33 is reduced.

Next, when adjusting the focus of the objective lenses 7 and 8 to the far side, the first operation wire 12 is moved back. As a result, the objective lens frame 6 is slid rearward, the objective lenses 7 and 8 are moved rearward, and at this time, the operating wire 36 is automatically retracted and the taper pin 35 is moved rearward. When the taper pin 35 passes through the state shown in FIGS. 14 and 15 and reaches the state shown in FIGS. Feather 31,3
The upper side of the aperture opening 33 is rotated in the direction of separation, and the opening amount of the aperture opening 33 becomes large.

It is of course possible to implement the present invention even if the objective lenses 7 and 8 are fixed and the image guide fiber 21 is moved to adjust the focus.

As explained above, the present invention is provided with an aperture mechanism that adjusts the brightness of the objective lens, and when adjusting the focus of the objective lens to the short distance side, the opening degree of the aperture mechanism is made small. Even if you adjust the focus position to a close distance, the depth of field will not become shallow, allowing you to observe the subject clearly.
It also eliminates the trouble of reducing the light intensity of the light source, and when taking photographs, the brightness on the film surface can be kept almost the same as when taking a long distance, and the error exposure time due to mechanical delay in exposure time control can be corrected. This has the effect that the exposure time is negligible, and it is possible to obtain photographs with proper exposure as in the case of long distances.

[Brief explanation of the drawing]

1 to 8 show one embodiment of the present invention, in which FIG. 1 is a perspective view showing an endoscope, FIG. 2 is a sectional view showing the distal end of the insertion section of the endoscope, and FIG. Figure 3 is a front view of the aperture mechanism with the aperture diameter reduced, Figure 4 is a side view thereof, Figure 5 is a front view of the aperture mechanism with the aperture diameter set to medium, and Figure 6 is its side view. A side view, FIG. 7 is a front view of the aperture mechanism showing a state where the aperture diameter is increased, FIG. 8 is a side view thereof, and FIG. 9 is a graph showing the depth of field when the aperture mechanism is provided.
FIG. 10 is a graph showing the depth of field when no aperture mechanism is provided, and FIGS. 11 to 17 show other embodiments of the present invention. A sectional view showing the tip, FIG. 12 is a front view of the aperture mechanism with the aperture diameter reduced, FIG. 13 is a longitudinal sectional view thereof, and FIG. 14 is the aperture mechanism with the aperture diameter in the middle. , FIG. 15 is a longitudinal sectional view thereof, FIG. 16 is a front view showing a state where the aperture diameter is increased, and FIG. 17 is a longitudinal sectional view thereof. 7, 8... Objective lens, 6, 12... Focus adjustment mechanism, 14, 30... Aperture mechanism.

Claims (1)

[Claims] 1. In an endoscope that illuminates the inside of a body cavity and is equipped with a focus adjustment mechanism for an objective lens, the brightness of the objective lens is adjusted in conjunction with the focus adjustment mechanism of the objective lens to adjust the focus of the objective lens to the near distance side. An endoscope characterized by being provided with an aperture adjustment mechanism that reduces the aperture opening of the diaphragm and increases the aperture opening when adjusting the focus to a far distance side.