JPH0574050B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens holding device that can be used for a photographing lens for a video camera.

BACKGROUND ART In recent years, with the spread of video cameras, the demand for photographic lenses has increased rapidly, and there has been a growing demand for smaller, lighter, and lower cost lenses. Attempts are also being made to improve productivity and adjustment accuracy by simplifying the structure and facilitating optical adjustment of the lens barrel that holds the lens.

Hereinafter, a conventional lens holding device will be described with reference to the drawings.

FIG. 4 is a partial sectional view of a conventional lens holding device, showing a structure often used for fixing a master lens group for adjusting the back focus of a zoom lens.

That is, lens spacers 2, 3,
Lenses 5, 6, and 7 are inserted through 4, and each lens is fixed by a lens holding screw 8.
The lens barrel 1 holding the lenses 2, 3, and 4 is inserted into the outer frame 9, and the groove 10 provided in the lens barrel 1 is located in the circular hole 11 of the outer frame 9 as shown in FIG. The eccentric pin 12 shown is inserted into the round hole 11, and the eccentric boss 13 at the tip of the eccentric pin 12 is engaged with the groove 10.

By rotating the eccentric pin 12, the lens barrel 1 is moved in the direction of the optical axis of the lens to perform back focus adjustment. After the adjustment is completed, the fixing screw 14 screwed into the outer frame 9 is tightened, and the tip of the fixing screw 14 locks the lens barrel. 1 is pressed and fixed, the eccentric pin 12 is removed, and the back focus adjustment of the lens system is completed.

Problems to be Solved by the Invention However, in the above conventional configuration, when adjusting the back focus, the amount of movement of the lens barrel 1 housing the lens is proportional to the rotation angle of the eccentric pin 12, as shown in FIG. Therefore, fine adjustment becomes difficult depending on the rotational position of the eccentric pin 12, and
Tightening the fixing screw may cause the lens barrel to move slightly, resulting in a problem of increased adjustment errors.

Furthermore, when the eccentric pin 12 is rotated in one direction, the direction of movement of the lens barrel 1 is reversed halfway, and the direction of rotation of the eccentric pin 12 and the direction of movement of the lens barrel 1 do not match, resulting in poor workability. There were also problems. Furthermore, since the lens and spacer are inserted into the lens barrel in a stacked manner, the lens tends to tilt and the number of assembly steps increases.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a lens holding device that allows fine adjustment of a lens barrel, good workability, and a reduction in assembly man-hours.

Means for Solving the Problems In order to achieve the above object, the lens holding device of the present invention includes a plurality of lenses and a holding groove for holding the lenses on the inner surface, and an optical axis of the lenses. a split lens barrel divided into two along a plane containing the split lens barrel, and a gear having a hole that can be fitted into the outer circumferential portion of the split lens barrel;
A positioning means for positioning the gear with respect to the divided lens barrel, an even number of male threads provided on the outer periphery of the divided lens barrel, and an even number of female threads screwed into the even number of male threads. The optical system includes an outer frame that holds the divided lens barrel, and a biasing means that biases the divided lens barrel in the optical axis direction with respect to the outer frame.

Effects According to the present invention, by driving the gear fitted to the lens barrel, the rotation angle of the gear and the amount of movement of the lens barrel are directly proportional, so that the optimum position of the back focus can be extremely easily determined. Adjustment accuracy can also be improved. Furthermore, when inserting a lens into the two-divided lens barrel, the lens can be inserted independently from a direction perpendicular to the optical axis, making assembly easier and reducing the number of assembly steps.

Embodiment A lens holding device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a partial sectional view of a lens holding device in an embodiment of the present invention.

In FIG. 1, two identically shaped divided lens barrels 20 and 21, which are divided into two along a plane including the optical axis 31, are made of resin material, and lenses 22, 23, 2
4, 25, and 26 are configured to be insertable in a direction perpendicular to the optical axis 31. The outer peripheral part of the lens 22 is held by a lens holding part 27 on the inner peripheral surface of the divided lens barrel 20, and the lens 22 is held by the lens regulating part 2 by an elastic piece 28 provided on the inner surface of the divided lens barrel 20.
By pressing 9, positioning in the optical axis direction is performed. Other lenses 23, 24, 25, 26
are held in the same way, and after inserting the lenses 22, 23, 24, 25, and 26 into one of the divided lens barrels 20, the other divided lens barrel 21 is covered, and the divided lens barrels 20, 21 are
At the same time, wrap the adhesive tape 30 around the outer circumference of the optical axis 3.
By inserting the ring-shaped gear 32 from one direction, the divided lens barrels 20 and 21 are brought into close contact with each other.

FIG. 2 is a sectional view showing the side shape of the gear 32, in which the convex portions 33 and 34 provided on the divided parts of the divided lens barrels 20 and 21 are engaged with the concave portion 37 on the inner circumference of the gear 32, and the convex The gear 32 and the divided lens barrels 20, 21 are positioned by engaging the portions 35, 36 and the recess 38. Split lens barrels 20 and 21 holding lenses
is inserted into the outer frame 39, and the two female threads 40 provided on the outer frame 39 are screwed together with the two male threads 41 of the split lens barrels 20, 21, and both ends of the split lens barrels 20, 21 are screwed together. The outer frame 3 is
9 and is guided so as to be movable in the direction of the optical axis 31. Between the gear 32 and the outer frame 39 are ring-shaped spacers 44a and 44b.
b is arranged, and the divided lens barrels 20 and 21 are connected to the outer frame 3.
9 in the direction of the optical axis 31. Further, a hole 46 for driving the gear 32 from the outside of the outer frame 39 is provided in a part of the outer frame 39.

The operation of the lens holding device configured as described above will be described below.

Split lens barrels 20 and 21 that hold lenses 22, 23, 24, 25, and 26 and have gears 32 inserted therein;
are spacers 44a, 44b, wave washers 45a, 4
5b and is screwed into the outer frame 39. When adjusting the back focus of the camera unit, an adjustment jig (not shown) having a gear-shaped driving section 47 is engaged with the gear 32 through a hole 46 provided in the outer frame 39. By rotationally driving, the divided lens barrels 20 and 21 are moved in the direction of the optical axis 31. At this time, as shown in FIG.
The amount of movement of the lens system in the lens system 1 is directly proportional to the two screw threads 40 and 41 screwed together. Furthermore, the lens barrel 20,
Since the two threads of screws No. 21 are biased in one direction,
The divided lens barrels 20 and 21 are attached to the outer frame 3 due to the frictional force of the threaded parts, etc.
Since it is immovably fixed to 9, the back focus adjustment will not shift even if the adjustment jig is removed.

As described above, according to this embodiment, lens assembly and back focus adjustment are facilitated, and it is possible to reduce assembly man-hours and improve adjustment accuracy.

In addition, in the above-mentioned embodiment, the female screw 40 and the male screw 41
We explained the configuration using double thread screws in 4.
By employing screws with an even number of threads, such as six threads or six threads, the threads are continuous during assembly, so parts of exactly the same shape (molded by the same mold) can be used for the divided lens barrels 20 and 21.

Effects of the Invention According to the present invention, a plurality of lenses, a divided lens barrel having a holding groove on the inner surface for holding the lenses and divided into two by a plane including the optical axis of the lenses;
A gear having a hole that can be fitted into the outer circumference of the divided lens barrel, a positioning means for positioning the gear with respect to the divided lens barrel, and an even number of male stripes provided on the outer circumference of the divided lens barrel. an outer frame that holds the segmented lens barrel and has a screw, an even number of female threads that are screwed into the even number of threads of the male thread, and biases the segmented lens barrel in the optical axis direction with respect to the outer frame. Because the lens barrel is equipped with a biasing means, the amount of movement of the lens barrel is directly proportional to the adjustment operation when adjusting the back focus, making adjustment easy. Adjustment accuracy is improved as there is no slight deviation. In addition, by using an even number of screws, when the two divided lens barrels are combined, the screw threads are continuous, so the same mold can be used when molding the divided lens barrels, and the molds can be molded together. There is little deterioration in optical performance such as lens inclination due to dimensional differences, the lens can be easily assembled, and excellent effects such as improved workability and reduced adjustment man-hours can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a lens holding device according to an embodiment of the present invention, Fig. 2 is a sectional view showing the side shape of the device, and Fig. 3 is a characteristic diagram showing the relationship between the rotation angle and the amount of movement of the device. , Fig. 4 is a partial sectional view of a conventional lens holding device, Fig. 5 is a perspective view of an eccentric pin that can be used in the device, and Fig. 6 is a characteristic diagram showing the relationship between the rotation angle and the amount of movement of the device. be. 20, 21... divided lens barrel, 22, 23, 24,
25, 26... Lens, 27... Lens holding part,
32... Gear, 33, 34, 35, 36... Convex portion, 37, 38... Concave portion, 39... Outer frame, 40...
...2 female threads, 41...2 male threads, 45
a, 45b...Wave washer.

Claims (1)

[Claims] 1 A plurality of lenses, a split lens barrel that has a holding groove on the inner surface for holding the lenses and is divided into two along a plane that includes the optical axis of the lenses, and can be fitted to the outer periphery of the split lens barrel. a gear having a hole, a positioning means for positioning the gear with respect to the divided lens barrel, an even number of male threads provided on the outer periphery of the divided lens barrel, and a screw threaded into the even number of male threads. It is characterized by comprising an outer frame that has an even number of female threads that fit together, and that holds the divided lens barrel, and a biasing means that biases the divided lens barrel in the optical axis direction with respect to the outer frame. A lens holding device.