JPH0743583A - Lens driving device - Google Patents

Abstract

PURPOSE:To remove the rotational backlash of a nut while absorbing deviation between a guide bar and a lead screw, and to directly transmit the rotational driving force of the lead screw to a lens holder without a time lag. CONSTITUTION:This lens driving device is provided with the lens holder 1 guided by the guide bar 4 disposed in parallel with an optical axis in a lens barrel, and the nut 8 screwed with the lead screw 6 and transmitting the driving force of the screw 6 to the lens holder 1; and the lens holder 1 is provided with a housing part 1d where the nut 8 can be relatively displaced to the holder 1 within a limited range on a plane perpendicular to the optical axis and can not relatively be displaced in an optical axis direction, and a shake preventing fitting part 1c regulating the rotation of the nut centering around the screw 6.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art There are various conventional lens driving devices of this type, and most of them drive a lens holder in a direction of an optical axis by a cam according to a moving amount, but recently, a stepping motor or the like is driven. As a source, there is used one that rotates a lead screw and drives a lens holder in the optical axis direction through a nut having a female screw portion that meshes with the lead screw.

In such a lens driving device, when the guide bar in the optical axis direction of the lens holder is provided in parallel with the lead screw in addition to the lead screw, the guide bar and the lead screw are separated from each other due to a manufacturing error or an assembly error. As shown in FIG. 5A, the nut 102 is attached to the nut engaging portion of the lens holder 101 so that the lead screw does not become exactly parallel or the guide bar is slightly inclined to adjust the tilt of the lens. Relative to 103,
A margin 104 is provided to absorb an error amount and an adjustment amount.

[0004]

However, in the above-described conventional example, since there is a margin 104 around the nut 102, there is some play even when the nut 102 rotates. Therefore, the lead screw 103 rotates and the nut 10
Lens holder 1 through nut 102
When driving 01, since the rotational force of the lead screw 103 cannot be directly transmitted to the lens holder 101, the rotation angle of the lead screw 103 and the extension of the lens holder 101 do not completely correspond to each other, and there is a time lag due to the rotational play. 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 for the amount of backlash caused by 04,
The driving force in the optical axis direction is transmitted to the nut 102.
Further, since the position of the lens holder 101 is displaced by the amount of play depending on the rotation direction of the screw, when the lens is stopped, there is a problem that the lens must always move in a fixed direction and then stop.

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

[0006]

According to the present invention, a lens holder guided by a guide bar disposed parallel to the optical axis in a lens barrel and a driving force of the lead screw screwed together. In the lens driving device having a nut for transmitting the lens holder to the lens holder, the lens holder is displaceable relative to the lens holder in a limited range within a plane in which the nut is perpendicular to the optical axis and in the optical axis direction. Has a storage portion that is not relatively displaceable and a steady rest fitting portion that restricts rotation of the nut around the lead screw, so that the inclination or positional relationship between the guide bar and the lead screw may cause manufacturing error or assembly. Even if there is a deviation due to an error or tilt adjustment, it is possible to absorb the deviation and eliminate the rotational rattling of the nut. Transmitted to the lens holder directly, but never produce a time delay.

[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. 1 and 2, 1 is a lens holder for holding a photographing lens, and 2 is a light. A guide bar 3 parallel to the axis is a metal tube that is inserted and fixed to the receiving tube portion (1a) of the lens holder 1, and the lens holder 1 is supported inside the metal tube 3 so as to be slidable in the optical axis direction. The guide bar is inserted. Reference numeral 4 denotes a steady bar which is arranged in parallel with the guide bar 2 and whose both ends are fixed to a ground plate (not shown). The steady groove portion (1b) of the lens holder 1 is fitted into this bar 4 so that the lens holder The shake in the rotation direction of is stopped. Reference numeral 5 denotes a tilt adjusting plate which holds one end of the guide bar 2 whose other end is fixed to a base plate (not shown). The tilt adjusting plate 5 is within a limited range within a plane perpendicular to the longitudinal direction of the guide bar 2. You can slide with. Reference numeral 6 denotes a lead screw, which has a magnet 7 fixed to one end thereof which serves as a rotor of a stepping motor, and the other end supported by a ground plate (not shown).

Reference numeral 8 denotes a nut having a female screw 8a which is screwed with the male screw of the lead screw 6.
Has a long groove portion 8b, and the long groove portion 8b is inserted into the housing portion 1d of the lens holder 1 so that the long groove portion 8b is fitted in the steady rest dowel 1c of the lens holder 1.

Next, the operation of the above embodiment will be described.
When the lead screw 6 rotates, the nut 8 is stopped in rotation by the steady rest dowel 1c, so that 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.

Ideally, the lead screw 6 and the guide bar 2 are ideally parallel and their relative positions are accurate, but in reality there are manufacturing errors, assembly errors, tilt adjustment, etc.
The lens holder 1 guided by the guide bar and the lead screw 6 are displaced in a limited range, and the nut 8
The lens holder 1 needs to be relatively displaceable in a plane perpendicular to the screw direction.

However, in this embodiment, as shown in FIGS. 2 and 3, since the long groove portion 8b of the nut 8 is fitted into the steady rest dowel 1c of the lens holder 1, the lens holder 1 and the lead screw 6 are It is possible to prevent backlash in the rotational direction while absorbing relative displacement in the direction perpendicular to the screw direction.

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

According to the second embodiment, the lead screw 1
Even when 6 is relatively displaced with respect to the lens holder 11, the protrusion 18a of the nut 18 maintains the fitting state with the steady portion 11a of the lens holder 11, so that there is no backlash. In the case of this embodiment, the nut 18 is strictly mathematically
When the lens is displaced, the steady rest 11a of the lens holder 11
Does not match the width of the protrusion 18a of the nut 18, but within a very small range, the steady rest 11 of the lens holder 11
If the distance a is widened, the rotational play will not occur in practice.

[0014]

As described above, according to the present invention,
The lens holder guided by the guide bar includes a storage portion in which the nut is relatively displaceable with respect to the lens holder within a limited range in a plane perpendicular to the optical axis, and is not relatively displaceable in the optical axis direction. Since the guide bar and the lead screw are configured to have the steady rest fitting portion that regulates the rotation of the nut around the lead screw, even if there is a positional deviation due to a manufacturing error, an assembly error, an inclination adjustment, or the like, While absorbing the relative displacement, the nut does not rattle. As a result, the rotational driving force of the lead screw is directly transmitted to the lens holder, and there is no time delay, and the rotation 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 correspond accurately. Moreover, there is an effect that it is not affected by the rotation direction of the screw.

[Brief description of drawings]

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

FIG. 2 is a front view of FIG.

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

[Explanation of symbols]

 1 lens holder 1c steady rest dowel (rest steady fitting part) 1d storage part 4 guide bar 6 lead screw 8 nut 8b long groove part

Claims (1)

[Claims] 1. A lens holder guided by a guide bar arranged in the lens barrel in parallel with the optical axis, and a nut screw-engaged with a lead screw and transmitting the driving force of the lead screw to the lens holder. In the lens driving device, the lens holder includes a storage portion in which the nut is relatively displaceable with respect to the lens holder within a limited range in a plane perpendicular to the optical axis, and is not relatively displaceable in the optical axis direction, A lens driving device, comprising: a steady rest fitting portion that restricts rotation of the nut about a lead screw.