JPS62262009A - Lens barrel - Google Patents

Abstract

PURPOSE:To incorporate a sensor in noncontact and without extensive remodeling of the constitution of a general lens barrel, by using a variation in the electrostatic capacity of a pair of variable capacitors. CONSTITUTION:The titled lens barrel is provided with fixed cylinders 3, 19, movable cylinders 16, 25 which are provided freely movably against these fixed cylinders 3, 19 and move forward and backward a movable lens by its position displacement, and sensors 31, 32 for detecting a position of these movable cylinders 16, 25, and as for the sensors 31, 32, a pair of electrodes 33, 34, 38 and 39 are provided adjacently on one of the fixed cylinders 3, 19 or the movable cylinders 16, 25, and on the other hand, electrodes 35, 40 which are opposed at a gap to a pair of electrodes 33, 34, 38 and 39 are provided, and a pair of variable capacitors 36, 37, 41 and 42 are formed. In this way, when the movable cylinder for moving forward and backward the movable lens is displaced, an opposed area of the electrodes in a pair of variable capacitors is varied, by which a displacement amount of the movable lens is detected by varying the electrostatic capacity of a pair of variable capacitors.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a camera lens II.

(Prior Art) In cameras, a device for detecting the position of a movable lens is incorporated with automation of autofocus and the like. Conventionally, as this type of device, for example, Japanese Patent Application Laid-Open No. 59-1
As shown in Publication No. 01609, a photocoupler type is provided in which a slit is provided in the optical path between the light emitting part and the light receiving part, the slit area is changed in conjunction with the displacement i of the movable lens, and the position of the movable lens is detected by the received light m. , also, JP-A-60-21
As shown in Japanese Patent No. 8612, a potentiometer system is known in which a potentiometer is configured by a distance ring, a resistor integrated with a brush, and a brush, and the displacement of a movable lens is detected by a change in resistance value.

(Problems to be Solved by the Invention) However, in the case of the photocoupler method described above, the light emitting element must be lit at all times, resulting in high current consumption, and furthermore, a light emitting part, a light receiving part, and a slit are required. Therefore, it cannot be built into a compact lens barrel. In addition, in the potentiometer method, the brush is brought into contact with the resistor, so
It requires a large torque from the drive source and has a contact point, which poses a problem in durability.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to enable a sensor to be built-in without contact and without making major modifications to the configuration of a conventional general lens barrel.

[Structure of the invention]

(Means for solving the problems) Lens t! of the present invention! The cylinder includes a fixed cylinder 3.19, a movable cylinder 16°25 which is movably provided with respect to the fixed cylinder 3, 19 and moves the movable lens forward or backward by changing its position, and a movable cylinder 16°25. a sensor 31 that detects
32, and the sensors 31 and 32 are connected to the fixed cylinder 3.
．． A pair of electrodes 33.34.38.39 are provided adjacent to each other on either one of the movable cylinder 16. 35, 40 are provided to form a pair of variable capacitors 36, 37, 41, and 42.

(Function) According to the present invention, when the movable cylinder that advances and retreats the movable lens is displaced, the opposing area of the electrodes in the pair of variable capacitors that constitute the sensor changes, thereby changing the capacitance of the pair of variable capacitors. This is to detect the amount of displacement of the movable lens, that is, the position of the movable lens.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a cylindrical base barrel, and a support part 2 is connected to the camera body via an adapter or the like at the rear of this base n1.
A cylindrical #R cylinder main body 4 is attached to the front part of the base cylinder 1 via a cylindrical fixed cylinder 3. The first, second, third lenses L1. A first lens group consisting of L2 and Ls is provided, and fourth, fifth, and sixth lenses L are provided inside the lens barrel body 4 via a second group lens frame 6.
4. A second detailed lens consisting of Ls and Le, and a third lens.
A third lens group consisting of a seventh lens L7 is provided via a group lens frame 7 so as to be movable in the axial direction. That is, the second group lens frame 6 and the third group lens frame 7 are supported by a plurality of guide shafts 8 provided in parallel at the upper and lower parts of the lens barrel main body 4 so as to be able to move forward and backward. Engagement elements 9 and 10 are provided protrudingly from the upper portions of the frame 6 and the third group lens frame 7, and each engagement element 9 and 10 is a cylindrical cam that is rotatably provided concentrically within the lens barrel body 4. An engaging element 13 is engaged with each cam groove of the barrel 11 and protrudes from the opening groove 12 in the circumferential direction of the lens barrel body 4 at the upper part of the cam barrel 11 . Further, a cylindrical zoom ring 14 is rotatably provided concentrically on the rear outer circumference of the ma main body 4, and the engager 13 of the cam cylinder 11 is engaged with the inside of this zoom ring 14. , the zoom lever 1 is located outside the zoom ring 14.
5, and a cylindrical movable barrel 16 facing the outer periphery of the fixed barrel 3 is integrally provided at the rear of the zoom ring 14.

When the zoom ring 14 is rotated by the zoom lever 15, the cam cylinder 1
1 rotates, and the second group lens frame 6 and the third group lens frame 7 advance and retreat in the axial direction along the guide shaft 8 via the engager 9.10 engaged with the cam groove, and the second group lens frame 6 and the third group lens frame 7 move forward and backward along the guide shaft 8, And the lenses L4 to L7 of the third group are moved forward and backward.

Further, a fourth lens group consisting of eighth and ninth lenses L[1, L9 is provided at the rear of the lens barrel body 4 via a fourth lens frame 17.

The first lens is inserted into the front part of the base barrel 1 through the fifth lens frame
0, 11th, and 12th lenses L1o, Lll.

A 59th lens group consisting of lenses 1 to 12 is provided, and a cylindrical fixed tube 19 is integrally provided at the rear of the fifth group lens frame 18. Further, the 13th and 14th lenses L13. L1
A sixth lens group consisting of two lenses is provided so as to be movable in the axial direction. That is, the sixth group lens frame 20 is supported by a guide shaft 21 provided in the base barrel 1 so as to be able to move forward and backward, and an actuating portion 22 is protruded from the upper part of the sixth group lens frame 20. A movable member 11i has an actuating portion 22 provided in the base barrel 1 or is connected to the drive shaft 24 of the near motor 23, and is located at the front of the sixth group lens frame 20 and faces into the fixed barrel 19.
25 are integrally provided.

Then, the linear motor 23 is driven to move the drive shaft 24 forward and backward, and the sixth group lens frame 20 is moved back and forth in the axial direction along the guide shaft 21 via the actuating section 22, so that the sixth group lens L13
．． It is designed to advance and retreat on L14.

The first to ninth lenses L1 to L9 constitute a zoom lens system, and the tenth to fourteenth lenses L1 to particularly constitute an imaging lens system.

Further, a sensor 31 that indicates the zoom lens position is provided between the base barrel 1 and the zoom ring 14, and a sensor 31 that indicates the position of the imaging lens between the fixed barrel 19 of the base t11 and the sixth group lens frame 20. A sensor 32 shown is provided.

As shown in FIGS. 1 and 2, the sensor 31 indicating the zoom lens position includes a pair of semicircular arc-shaped electrodes 33.
34 are installed adjacent to each other in an insulated state, and have a substantially semicircular arc shape having a length longer than the rotation length of the zoom ring 14 in the circumferential direction of the inner circumference of the movable barrel 16 at the rear of the zoom ring 14. An electrode 35 is attached to the fixed cylinder 3.
The electrodes 33 and 34 of the e-tube 16 and the electrodes 35 of the e-tube 16 are arranged oppositely with a small gap between them, and the two variable capacitors 36 and 37
It consists of

As shown in FIGS. 1 and 3, the sensor 32 that indicates the position of the imaging lens includes a pair of M poles 38 that are cylindrical in the axial direction of the inner circumference of the fixed barrel 19 at the front part of the base barrel 1. .39
are mounted adjacent to each other in an insulated state, and a cylindrical electrode 40 having a width equal to or larger than the movement 3 of the sixth group lens frame 20 is provided on the outer periphery of the movable cylinder 25 at the front part of the sixth group lens frame 20. is attached to the electrode 3 of the fixed cylinder 19.
8.39 and the electrode 40 of the movable cylinder 25 are disposed opposite to each other with a small gap between them to form two variable capacitors 41 and 42.

Further, as shown in FIG. 4, the sensor 31 indicating the zoom lens position is connected to a zoom lens position determining section 43, and this zoom lens position determining section 43 receives the position instruction i! ! 1
The sensor 32, which is connected to the position correction section 45 at 44 and indicates the position of the imaging lens, is connected to the imaging lens position determination section 4G, and this imaging lens position determination section 4G is connected to the position indication section 44. . In addition, the position indicating section 44
A position setting unit 47 is connected to determine the position of the imaging lens, and this position indicating unit 44 is connected to a drive unit 48 having the linear motor 231.
is an imaging lens position determination unit 46 that converts the value of the sensor 32.
This constitutes a servo system that moves forward and backward until the outputs of the position setting section 47 and the position setting section 47 become equal.

Next, the operation will be explained.

The image of the subject is captured by each lens L1 to L11 in the first to sixth groups.
4, the image is formed on the film of the camera body.

When photographing, the linear motor 23 is operated to move the sixth group lens frame 20 forward and backward, and the 13th and 14th lenses L13 . Focusing is performed by moving back and forth through L14. At this time, the position setting section 47 sets the photographing distance manually or by using an autofocus function, and outputs the signal to the position instruction section 44.

At the same time, the sensor 32 indicating the position of the imaging lens is activated. That is, when the imaging lens is at the center of displacement, the opposing areas of the pair of electrodes 38 and 39 of the fixed barrel 19 with respect to the electrode 40 of the variable vJ barrel 25 of the sixth group lens frame 20 are equal, and the area of the pair of variable capacitors 38 and 39 is equal. The capacitances of 41° and 42 are equal. Then, together with the movable cylinder 25, the electrode 40
A pair of electrodes 38.3 of the fixed cylinder 19 are moved forward and backward.
For example, when the photographing distance is short and the sixth detailed lens is moved to a position more forward than the previous position, the capacitance of one variable capacitor 41 increases, and the capacitance of the other variable capacitor 42 increases. The capacitance of
On the other hand, when the focusing distance is long and the sixth group lens is placed at a rear position from the front position, the capacitance of one variable capacitor 41 decreases, and the capacitance of the other variable capacitor 42 increases. As such, the capacitance of the pair of variable capacitors 41 and 42 changes in conjunction with the displacement of the sixth lens group, and this is output as the position of the sixth lens group. Based on the output from the sensor 32 indicating the position of the imaging lens, the imaging lens position determination unit 46 determines the position of the lens of the sixth group, and outputs this signal to the position indication unit 44, where the position setting is performed. The position of the imaging lens corresponding to the fi shadow distance from the position indicating section 47 is compared, and the linear motor 23 in the driving section 48 is driven based on the output from the position indicating section 44, and the sixth group lens is set at the indicated position 8. Then, focusing is performed.

In addition, when changing the magnification during shooting, the zoom ring 14 is rotated to move the second FJ and third group lenses forward and backward, and the fourth, fifth, and sixth movable lenses of the zoom lens system are moved forward and backward.
and the seventh lens L4, Ls.

Move 1G and L7 forward and backward to change the magnification. At this time, the sensor 31 indicating the zoom lens position η is activated. That is, when the zoom lens is at the center of displacement, the zoom ring 14
The opposing areas of the pair of electrodes 33 and 34 of the fixed cylinder 3 with respect to the electrode 35 of the movable cylinder 16 are equal, and the capacitances of the pair of variable capacitors 36 and 37 are equal. Then, by rotating the electrode 35 together with the movable barrel 16 of the zoom ring 14, the opposing areas of the pair of electrodes 33 and 34 of the fixed barrel 3 are changed, for example, to obtain a larger magnification than the previous state. One variable capacitor 36
As the capacitance of the variable capacitor 36 increases, the capacitance of the other variable capacitor 31 decreases.Conversely, when the magnification is made smaller than the previous state, the capacitance of the variable capacitor 36 decreases and the capacitance of the other variable capacitor 31 decreases. , the other variable capacitor 3
In this way, the capacitance of the pair of variable capacitors 36 and 37 increases in conjunction with the displacement of the second and third group lenses.
The capacitance a changes, and this is output as the position of the second and third group lenses. Then, when the magnification of the zoom lens is changed, the sensor 31 that indicates the zoom lens position outputs the position, and the position is outputted by the zoom lens position determination unit 43 to the second group,
The position of the third group lens is determined and this signal is sent to the position indicating unit 4.
4, the correction values corresponding to the positions of the second and third lens groups are output from the position correction section 45, and the drive section 48 is driven by the linear motor 23 based on the output from the position instruction section 44. The sixth lens group of the imaging lens is set accurately at a position corresponding to the magnification.

By doing as described above, the fixed barrel 3, which is the connection part between the base barrel 1 and the lens barrel main body 4, the zoom ring 14, the fixed barrel 19 in the base barrel 1, the movable barrel 25 of the sixth group lens frame 20, etc. The sensors 31 and 32 can be incorporated in a very natural form within the lens barrel, which is an assembly of cylindrical parts.
The fixed cylinder 19 provided with poles 38 and 39 can also be used as a light shielding member.

Further, by using electrostatic IFffi type sensors 31 and 32, it is possible to make the sensor non-contact and save current.

In addition, each electrode 33, 34, 35, 38, 39, 40 can be easily formed by applying metal plating to the inner or outer surface of the synthetic resin cylinder and then cutting the insulating part. Furthermore, by interposing a substance with a high dielectric constant in the gap between the opposing electrodes, the electrostatic capacitance l can be increased and the detected viscosity can be improved.

In addition, in implementation, the fixed tube and the movable tube may be combined with either the inner or outer tube, and the pair of electrodes and the electrodes facing these may be arranged in the fixed tube and the movable tube in the same manner as in the above embodiment. Furthermore, as in the sensor of the embodiment described above, the movable cylinder may be provided so as to be able to move forward and backward in the axial direction or rotate in the circumferential direction with respect to the fixed cylinder, so that the pair of electrodes can be moved in the axial direction or in the circumferential direction. They should be installed in parallel.

〔Effect of the invention〕

According to the present invention, a sensor can be incorporated in a contactless, current-saving manner, and without making any major modifications by using the same lens barrel.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a longitudinal sectional view showing an embodiment of the lens barrel of the present invention, FIG. 2 is an open view of a part of FIG. 1, and FIG. A partial perspective view and FIG. 4 are circuit block diagrams. 3.19...Fixed tube, 16.25...Movable tube, L4゜L
s, Le, Ly, 113.114... 2nd group, 3rd group, 6th group lenses as movable lenses, 31.32.
・Sensor, 33.34.38.39...Pair of electrodes, 3
5゜40...electrode, 36.37.41.42...capacitor again.

Claims (3)

[Claims] (1) A fixed tube, a movable tube that is movably provided with respect to the fixed tube and moves the movable lens forward or backward by its positional displacement, and a sensor that detects the position of the movable tube, and the sensor detects the position of the movable tube. A lens mirror characterized in that a pair of electrodes are provided adjacent to each other on either one of a tube or a movable tube, and an electrode that faces the pair of electrodes with a gap is provided on the other side to form a pair of variable capacitors. Tube. (2) The lens barrel according to claim 1, wherein the movable barrel is provided so as to be able to move forward and backward in the axial direction with respect to the fixed barrel, and a pair of variable capacitors for the sensor are formed in the axial direction. (3) The lens barrel according to claim 1, wherein the movable barrel is provided to be rotatable in the circumferential direction relative to the fixed barrel, and a pair of variable capacitors for the sensor are formed in the circumferential direction.