JP3031127B2 - Lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for a camera for driving a lens holder in an optical axis direction.

[0002]

2. Description of the Related Art Conventionally, there are various types of lens driving devices of this type, and in many cases, a lens holder is driven in a direction of an optical axis by a cam corresponding to a feeding amount, but recently, a stepping motor or the like is driven. As a light source, one that rotates a lead screw and drives the lens holder in the optical axis direction via a nut having a female thread portion that meshes with the lead screw is used.

[0003] In such a lens driving device, when a guide bar in the optical axis direction of the lens holder is provided in parallel with the lead screw separately from the lead screw, the guide bar and the lead screw may be separated due to a manufacturing error, an assembly error, and the like. As shown in FIG. 5A, a nut 102 is attached to a nut engaging portion of the lens holder 101 so that the guide bar does not become strictly parallel or the guide bar is slightly inclined to adjust the inclination of the lens. Relative to 103,
A margin 104 is provided to absorb the error and the adjustment.

[0004]

However, in the above-mentioned conventional example, since there is a margin 104 around the nut 102, rattling occurs even when the nut 102 rotates. For this reason, the lead screw 103 rotates and the nut 10
2 and the lens holder 1 through the nut 102.
01, the rotation force of the lead screw 103 is not directly transmitted to the lens holder 101, so that the rotation angle of the lead screw 103 does not completely correspond to the extension of the lens holder 101, and a time delay of the rotation backlash occurs. Occurs. In particular, as shown in FIGS. 5B and 5C, when the rotation direction of the lead screw 103 changes, the allowance 1
After the nut 102 idles by the amount of play due to 04,
The driving force in the optical axis direction is transmitted to the nut 102.
In addition, since the position of the lens holder 101 is shifted by the amount of play depending on the rotation direction of the screw, there is a problem that the lens must be moved in a certain direction and then stopped when stopping the lens.

An object of the present invention is to provide a lens driving device which solves the above problems.

[0006]

According to the present invention, there is provided a lens driving device comprising: a lens holder which is guided by a guide bar disposed in a lens barrel in parallel with an optical axis; A lens driving device having a nut for transmitting a driving force to the lens holder, wherein the lens holder is provided with a storage portion for storing the nut such that the nut does not relatively displace in the optical axis direction with respect to the lens holder. The nut or the lens holder is characterized in that the nut or the lens holder is provided with restricting means for permitting a radial displacement of the nut in the lead screw and restricting a displacement of the nut in a rotational direction about the lead screw.

[0007]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention, and FIG. 2 is a front view of an assembled state thereof. In FIGS. The guide bar 3 parallel to the axis is a metal tube inserted and fixed in the receiving tube portion (1a) of the lens holder 1, and supports the lens holder 1 inside the metal tube 3 so as to be slidable in the optical axis direction. Guide bar is inserted. Reference numeral 4 denotes a steady rest bar which is disposed in parallel with the guide bar 2 and both ends of which are fixed to a base plate (not shown). The steady rest groove (1b) of the lens holder 1 fits into this bar 4, and The rotation in the rotation direction is stopped. Reference numeral 5 denotes a tilt adjusting plate holding one end of the guide bar 2 whose other end is fixed to a base plate (not shown). The tilt adjusting plate 5 is provided within a limited range in a plane perpendicular to the longitudinal direction of the guide bar 2. Is slidable. Reference numeral 6 denotes a lead screw. The lead screw 6 has one end to which a magnet 7 serving as a rotor of a stepping motor is fixed, and the other end supported by a base plate (not shown).

Numeral 8 denotes a nut having a female thread 8a screwed with the male screw of the lead screw 6.
Has a long groove portion 8b, and is inserted into the housing portion 1d of the lens holder 1 so that the long groove portion 8b is fitted into the steady resting dowel 1c of the lens holder 1. Here, the long groove portion 8b
The steady stop dowel 1c constitutes one element of a restricting means for permitting radial displacement of the lead screw 6 of the nut 8 and restricting displacement of the nut 8 in the rotational direction about the lead screw 6.

Next, the operation of the above embodiment will be described.
When the lead screw 6 rotates, since the rotation of the nut 8 is stopped by the steady rest dowel 1c, the nut 8 is moved in the axial direction along the lead of the screw. Since the nut 8 is inserted into the housing portion 1d of the lens holder 1, the movement of the nut 8 is directly transmitted to the lens holder 1, and the lens holder 1 moves along the guide bar 2.

It is ideal that the lead screw 6 and the guide bar 2 are ideally parallel and the relative positions are accurate. However, in practice, there are manufacturing errors, assembly errors, inclination adjustments, and the like.
The lens holder 1 and the lead screw 6 guided by the guide bar are displaced within a limited range, and the nut 8
The lens holder 1 and the lens holder 1 need to be relatively displaceable in a plane perpendicular to the screw direction.

In this embodiment, however, since the long groove 8b of the nut 8 is fitted to the steadying dowel 1c of the lens holder 1 as shown in FIGS. It is possible to prevent rattling in the rotation direction while absorbing relative displacement in the direction perpendicular to the screw direction.

Embodiment 2 FIG. FIG. 4 shows a second embodiment of the present invention, in which a nut 18 is provided with a protrusion 18a for stopping rotation, and a lens holder 11 is provided with a steady-state stop 11a for fitting the protrusion 18a. .

According to the second embodiment, the lead screw 1
Even if the member 6 is displaced relative to the lens holder 11, the protrusion 18a of the nut 18 maintains the fitted state with the steady portion 11a of the lens holder 11, so that there is no rotation play. In this embodiment, strictly mathematically the nut 18
When the lens is displaced, the steady portion 11a of the lens holder 11
Does not coincide with the width of the projection 18a of the nut 18, but in a minute range,
If the distance a is widened, there is practically no rotation play. Here, the protruding portion 18a and the steadying portion 11a constitute one element of a restricting means for restricting displacement in the rotation direction about the lead screw 16.

[0014]

As described above, according to the present invention,
Even if there is a positional deviation between the guide bar and the lead screw due to a manufacturing error, an assembly error, a tilt adjustment, or the like, the relative displacement can be absorbed by the restricting means allowing the nut to be displaced in the lead screw radial direction. And
Since the restricting means restricts the displacement of the nut in the rotation direction about the lead screw, the lead screw does not run idle. As a result, an effect is obtained in which the rotational angle of the lead screw and the amount of extension of the nut in the axial direction, that is, the amount of extension of the lens holder, can be accurately matched while absorbing the displacement between the guide bar and the lead screw. .

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a lens driving device according to a first embodiment of the present invention.

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a front view showing an eccentric state of a lens holder and a nut.

FIG. 4 is a front view showing a second embodiment of the present invention.

FIG. 5 is a front view showing a conventional rotation play of a lens holder and a nut.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens holder 1c Anti-sway dowel (anti-sway fitting part) 1d Storage part 4 Guide bar 6 Lead screw 8 Nut 8b Long groove part

Claims (1)

(57) [Claims] 1. A lens holder guided by a guide bar disposed parallel to an optical axis in a lens barrel, and a nut screwed to a lead screw and transmitting a driving force of the lead screw to the lens holder. In the lens driving device having the lens holder , the nut is provided with the lens holder
The nut so that it is not displaced relative to the
Is formed, and the nut or the
The lead screw of the nut is attached to the lens holder
Centering on the lead screw
A lens driving device having a restricting means for restricting a displacement in a rotation direction .