JPH0777646A - Lens barrel - Google Patents

Abstract

PURPOSE:To provide the lens barrel with which a higher speed of focusing, silent driving and miniaturization are attanable. CONSTITUTION:The surface of a holding member 20 of the lens barrel in which a lens 4 is housed movably in an optical axis direction via this holding member 20 is provided with a driven side magnetic member 23 and this driven side magnetic member 23 is provided with a driving source which has a driving side magnetic member 25 to be magnetically attracted to the driven side magnetic member 23 and drives the lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel which accommodates, for example, a zoom lens and a focusing lens so as to be movable in the optical axis direction via a holding member.

[0002]

2. Description of the Related Art FIG. 4 is a vertical sectional view showing a conventional lens barrel. In FIG. 4, reference numeral 1 is a front lens fixed to the front part of the lens barrel body 100, and 2 is a variable magnification lens held by a holding member 2a, which is wired in the lens barrel body 100 in parallel with the optical axis. It is supported by a guide bar and a detent bar (not shown) so as to be movable in the optical axis direction via a holding member 2a.

Reference numeral 3 is an afocal lens fixed in the lens barrel main body 100, and 4 is a focusing lens held by a holding member 5. The holding member 5 is attached to a guide bar 6 arranged parallel to the optical axis. The sleeve 5a is fitted, and the detent bar 7 arranged parallel to the guide bar 6 is engaged with the peripheral recessed portion 5b of the holding member 5 to be supported movably in the optical axis direction.

Reference numeral 8 is a metal plate integrally screwed to the holding member 5, 9 is a rack which is freely rotatable and is engaged with the metal plate 8 without back and forth, and 10 is a screw rod which is an output shaft of the stepping motor 11. The screw rod 10 is screwed into the rack 9 and is screwed into the rack 9 without any play due to the biasing force of a spring (not shown).

Next, the operation will be described. When the stepping motor 11 is operated by an electric circuit (not shown),
The holding member 5 is moved in the optical axis direction via the screw rod 10, the rack 9, and the metal plate 8 which are the output shafts, and focusing is performed by moving the focusing lens 4 in the optical axis direction.

[0006]

However, in the above-mentioned conventional example, when the holding member of the focusing lens is driven via the screw rod and the rack, the rack and the screw rod are spring-biased so that there is no backlash. Or, in order to use the equalize structure, when trying to correspond to faster autofocus,
It was difficult because there was a problem that the screws of the rack and the screw rod went out of sync. Further, noise caused by speeding up was also a big problem. Therefore, in the conventional example, there are limits in (1) speeding up autofocus, (2) quiet driving, and (3) satisfying miniaturization.

An object of the present invention is to obtain a lens barrel that solves the above problems.

[0008]

According to the present invention, in a lens barrel in which a lens is housed movably in the optical axis direction via a holding member, a driven side magnetic member is provided on the surface of the holding member. By providing a driving magnetic member that magnetically attracts the driven magnetic member and having a driving source that drives the lens, it is possible to achieve high-speed autofocus, silent operation, and downsizing.

[0009]

Embodiment 1 FIG. 1 is a longitudinal sectional view taken along line II of FIG. 2 of a lens barrel showing Embodiment 1 of the present invention, FIG. 2 is a cross sectional view taken along line II-II of FIG. 1 is an enlarged view of the main part of FIG.
In FIG. 3, reference numeral 1 is a front lens fixed to the front part of the lens barrel body 100, 2 is a zoom lens held by a holding member 2a, 3 is an afocal lens fixed inside the lens barrel body 100, Reference numeral 4 denotes a focusing lens, which are shown in FIG.
The same optical system as the conventional lens barrel shown in FIG.

A holding member 20 holds the focusing lens 4, and a sleeve 20a is fitted to a guide bar 21 arranged in parallel with the optical axis, and is arranged in parallel with this guide bar 21. The rotation preventing bar 22 is engaged with the peripheral edge concave portion 20b of the holding member 20, and is supported so as to be movable in the optical axis direction.

Reference numeral 23 denotes a magnet plate as a driven side magnetic member having a N-pole magnetic pole of a permanent magnet, which is fixed to the surface of the sleeve 20a of the holding member 20 in parallel with the guide bar 21. Reference numeral 24 denotes a magnet square bar having a plurality of pairs of N and S magnetic poles, which is adhesively fixed to the surface of the holding member 20.

Reference numeral 25 denotes a drive ring as a drive side magnetic member, which is a rubber ring containing a magnet as a flexible member containing a magnetic pole of S pole in rubber. Reference numeral 26 is an ultrasonic motor as a drive source for driving the focusing lens 4 back and forth along the optical axis, and the drive ring 25 is fixed to the output shaft 26a.

The ultrasonic motor 26 is arranged so that the drive ring 25 is in pressure contact with the magnet plate 23.
It is fixed to the lens holding portion 27 of No. 0 with a screw 28. Two
Reference numeral 9 denotes a magnetoresistive effect element (hereinafter, referred to as MR element) fixed to the surface of the holding member 20 so as to face the movement trajectory of the magnet square rod 24, and 30 processes a position signal of the focusing lens 4. Signal processing circuit and ultrasonic motor 2
6 is a circuit board including a drive circuit of No. 6;

The operation of the above embodiment will be described below. When a power switch (not shown) is turned on, the ultrasonic motor 26 operates by receiving a drive signal from the drive circuit of the circuit board 30, and drives the ultrasonic motor 26 via the drive ring 25 and the magnet plate 23 that are magnetically attracted to each other. Force holding member 2
0, the end surface 20c of the holding member 20 is abutted against the end surface of the lens holding portion 27, and the initial position is set by the MR element 29 and the magnet square rod 24, and stored in a CPU (not shown).

In this case, the MR element 29 can detect the initial position with high accuracy without contacting the magnet square rod 24.

Thereafter, the driving force of the ultrasonic motor 26 is transmitted to the holding member 20 via the driving ring 25 and the magnet plate 23, and the holding member 20 of the focusing lens 4 is moved in the optical axis direction without slipping. Then, the focusing lens 4 is driven along the optical axis for focusing. In this case, by making the driving ring 25 a flexible member, the frictional force with the magnet plate 23 is strengthened, and the driving force is transmitted more reliably.

In the illustrated example, the driving of the focusing lens 4 has been described. However, also in the driving of the magnification varying lens 2, the driving force is transmitted through a magnetic member that magnetically attracts in the same manner as described above. You can also

[0018]

As described above, according to the present invention,
Since the driven side magnetic member is provided on the surface of the lens holding member, the driving force of the driving source is transmitted to the lens holding member via the driving side magnetic member that magnetically attracts the driven side magnetic member. , The power from the driving source can be transmitted to the holding member of the lens without loss, and the holding member can be driven with high accuracy in the optical axis direction. (1) Speedup of autofocus, (2) It is effective in achieving quiet drive and (3) miniaturization.

[Brief description of drawings]

FIG. 1 is a view showing the lens barrel I of FIG. 2 showing an embodiment of the present invention.
-A longitudinal cross-sectional view taken along the line I.

FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged view of a main part thereof.

FIG. 4 is a vertical sectional view of a conventional lens barrel.

[Explanation of symbols]

 4 lens (focusing lens) 20 holding member 23 magnet plate (driven side magnetic member) 25 drive ring (drive side magnetic member) 26 ultrasonic motor (drive source)

Claims (2)

[Claims] 1. A lens barrel in which a lens is accommodated via a holding member so as to be movable in the optical axis direction, a driven-side magnetic member is provided on the surface of the holding member, and magnetic attraction is applied to the driven-side magnetic member. A lens barrel having a side magnetic member and a drive source for driving the lens. 2. The lens barrel according to claim 1, wherein the drive-side magnetic member is a flexible member.