JP3186543B2 - 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 moving a lens frame holding a lens in an optical axis direction.

[0002]

2. Description of the Related Art Conventionally, a rear focus type photographing lens comprising a fixed lens group, a variable power lens group (focus correction lens group) and a focusing lens group is shown in FIGS. A lens driving device as shown is used.

That is, the lens driving device shown in FIG. 3 has a pair of guide shafts 21 and 22 which are parallel to the optical axis X and parallel to each other. One of the guide shafts 21 extends through a guide hole 25 provided in the sleeve portion 24 of the focus lens holding frame 23. Also, the other guide shaft 22
Extends through the U-shaped groove 26 provided in the focus lens holding frame 23, whereby the focus lens holding frame 23 is movable in the optical axis direction and in a direction orthogonal to the optical axis X. Cannot rotate.

[0004] Further, a connecting shaft 27 facing the optical axis direction is provided on a sleeve portion 24 provided on the focus lens holding frame 23, and a connecting piece 28 is provided on the connecting shaft 27. The connecting piece 28 includes a rack 3 that meshes with a lead screw 30 of a motor 29 that is a driving source.
1 and a pressing portion 32 for pressing the rack portion 31 against the lead screw 30 while being sandwiched between the rack portion 31 and the lead portion 30.

On the other hand, a drive motor 29 having a shaft formed with a lead screw 30 meshingly engaged with the rack 31 of the connecting piece 28 being pressed is a U-shaped bracket 33.
Mounted on

[0006] In the lens driving device constructed as described above, when the driving motor 29 rotates, the motor 29 rotates.
The connecting piece 28 meshed and connected to the lead screw 30 of the shaft portion, and the focus lens holding frame 23 connected to the connecting piece 28 via the connecting shaft 27 are arranged in the rotational direction and the amount of rotation of the motor 29. Accordingly, it moves along a pair of guide shafts 21 and 22. That is, the motor 29 moves along the optical axis direction.

Also, in the lens driving device shown in FIG.
It has a pair of guide shafts 41 and 42 which are parallel to each other, and one of the guide shafts 41 and 42
Reference numeral 1 extends through a guide hole 45 provided in the sleeve portion 44 of the focus lens holding frame 43. The other guide shaft 42 extends through a U-shaped groove 46 provided in the focus lens holding frame 43 so that the focus lens holding frame 43 can move in the optical axis direction and Rotation is not possible in the direction perpendicular to the axis X.

Further, a plate-like projection 54 is provided integrally with the focus lens holding frame 43.

On the other hand, a motor 49, which is a drive source having a lead screw 50 formed on a shaft portion, is mounted on a U-shaped bracket 53, and a connecting shaft parallel to the lead screw 50 is attached to the U-shaped bracket 53. 47 are provided.

The connecting shaft 47 is connected to a connecting piece 48.
The connecting piece 48 is connected to the lead screw 5.
0, a pressing portion 52 for pressing the rack portion 51 against the lead screw 50, and a U-groove portion 55 for sandwiching a plate-like projection portion 54 provided on the focus lens holding frame 43. I have.

[0011] Even in the lens driving device constructed as described above, when the driving motor 49 rotates, the connecting piece 48 meshed with the lead screw 50 of the shaft of the motor 49 moves. When moving, the focus lens holding frame 43 connected to the connecting piece 48 is
A pair of guide shafts 41 according to the rotation direction and the rotation amount of
Move along 42. That is, the motor 49 moves in the direction of the optical axis X.

In any of the conventional lens driving devices constructed as described above, in any case, the deviation of the parallelism between the guide shaft and the lead screw can be detected by the pinching by the connecting frame or the focusing by the connecting frame. Although it is made to absorb by sandwiching it with the lens holding frame, for this reason,
The connecting frame and the connecting shaft must be manufactured separately from the focus lens holding frame, which has a problem that the manufacturing cost is high.In addition, since the number of parts is large, the assembling work becomes complicated, and There was a problem that it became expensive.

The present invention solves the above-mentioned problems of the prior art, and can absorb the deviation of the parallelism between the guide shaft and the lead screw with a simple structure, and can reduce the number of parts used. It is an object of the present invention to provide an inexpensive lens driving device as a whole, while reducing the manufacturing cost and facilitating the assembling work to reduce the number of assembling steps.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a guide hole and a U-shaped groove which face in the optical axis direction.
And a lens holding frame that is provided in parallel with the optical axis.
Through the guide hole and the U-shaped groove to hold the lens.
A guide shaft movably supporting the frame, and the lens holding frame
To the direction perpendicular to the optical axis.
A sheet-like projection that can be sexually displaced;
Rack part provided on the body and provided substantially parallel to the optical axis
And a lead engaged with the rack portion in a pressed state.
And the lead screw is rotationally driven.
A drive source, the rack part and the lead screw
Are on the extension of the line connecting the center of the guide hole and the optical axis.
A means configured to engage in a displaced position is employed.
It was used. In addition, the thin plate-shaped projection is made of a lubricating material.
The method used was a fee.

[0015]

According to the present invention, the above means are employed.
Drive the drive source to rotate the lead screw.
When the lens is moved, the rotation of the lead screw
Transmitted to the rack, and the lens holding frame
It will move in the optical axis direction. In this case, the rack
The lead screw is in mesh engagement with the lead screw
Therefore, the parallelism between the lead screw and the guide shaft is slightly
Even if it is
You. In addition, the rack and the lead screw are
At a position offset from the extension of the line connecting the center of the
Because it is engaged, it is orthogonal to the optical axis on the lens holding frame
Direction (the direction of rotation about the center of the guide hole)
A force acts, and this force causes the inner surface of the U-shaped groove to
Direction perpendicular to the optical axis of the lens holding frame
(Rotation around the center of the guide hole)
Is prevented, and the lens holding frame moves along the guide axis.
In this case, the optical axis is prevented from being blurred.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lens driving device according to the present invention shown in the drawings will be described. FIGS. 1 and 2 show a lens driving device according to the present invention, in which a pair of guide shafts 1 and 2 parallel to an optical axis X and a focus lens holding supported by the guide shafts 1 and 2 are shown. The frame 3 and a pulse motor 9 as a driving source attached to the U-shaped bracket 13
With

The focus lens holding frame 3 has a sleeve portion 4 through which one guide shaft 1 penetrates. That is, the sleeve portion 4 is provided with a pair of protrusions 4a, 4b in a direction orthogonal to the optical axis X in a state facing the optical axis direction, and the central axis of the two protrusions 4a, 4b is in the direction of the optical axis. Guide holes 5a and 5b are respectively formed.

One of the projections 4a is elastically displaceable in a direction perpendicular to the optical axis X, and is integrally provided with a thin plate-like projection 8 provided with a rack 11 on its outer surface. ing.

Further, a U-shaped groove 6 is provided in the focus lens holding frame 3 on the side opposite to the guide hole 5a with respect to the optical axis X, and the other guide shaft 2 is inserted into the U-shaped groove 6. Thereby, the focus lens holding frame 3 is movable in the optical axis direction along the guide shafts 1 and 2, and
It cannot be moved in a direction perpendicular to the optical axis X.

On the other hand, the pulse motor 9 attached to the U-shaped bracket 13 is formed on a lead screw 10 whose shaft portion meshes with and engages with the rack portion 11. The lead screw 10 is attached to a support (not shown) while the rack 11 provided on the focus lens holding frame 3 is elastically pressed. In this case, the rack and lead screw
Is the extension of the line connecting the center of the guide hole 5a and the optical axis.
It is designed to be engaged at a position shifted from the position. In addition, 14 and 14 are mounting holes for mounting the U-shaped bracket 13 to the support portion.

In the lens driving apparatus according to the present invention, the pulse motor 9 is started to rotate the lead screw 10 which is the shaft of the pulse motor 9, and this rotation is performed by the lead. The light is transmitted to the rack portion 11 of the focus lens holding frame 3 which is engaged with the screw 10 in a pressed state. Therefore, the focus lens holding frame 3 moves in the optical axis direction according to the rotation direction and the rotation amount of the pulse motor 9.

In this case, when the parallelism with the guide shaft 1 is shifted, the lead screw 1 which is the shaft of the pulse motor 9 is
0 is attached, the rack 11 provided on the outer surface of the thin plate-like projection 8 provided on the focus lens holding frame 3 is connected to the lead screw 10 of the pulse motor 9.
Therefore , a slight shift in parallelism can be tolerated. Therefore, the assembling work becomes easy. Furthermore, the rack 11 and the lead
The screw 10 connects the center of the guide hole 5a and the optical axis.
Since it is engaged at a position shifted from the extension of the line,
The focus lens holding frame 3 has a direction (gamut) perpendicular to the optical axis.
In the direction of rotation about the center of the id hole 5a).
This force causes the inner surface of the U-shaped groove 6 to move
To the optical axis of the focus lens holding frame 3
Orthogonal direction (rotation about the center of the guide hole 5a
Backlash), and the focus lens holding frame
When the optical axis 3 moves along the guide axes 1 and 2,
It can be prevented.

In the case of the above, when the focus lens holding frame 3 is formed, the thin plate-like projection 8 having the rack 11 on the outer surface is formed of the same material, or the wear of the rack 11 is taken into consideration. In this case, the focus lens holding frame 3 may be formed of a molding material for high precision parts such as polycarbonate, and the thin plate-like projections 8 may be integrally formed of a lubricating material such as polyacetal.

In the above embodiment, the projections 4a and 4b provided on the sleeve 4 of the focus lens holding frame 3 are used.
One of the protrusions 4a is provided with the thin plate-like protrusion 8 having the rack portion 11 on the outer surface, but the portion where the thin plate-like protrusion 8 is provided is not particularly limited.

Further, a rack portion 11 is provided on the inner surface of the thin plate-shaped projection 8, and the thin plate-shaped projection 8 is engaged with the lead screw 10 in a state where the thin plate-shaped projection 8 is pushed and opened.
0 may be elastically engaged with each other.

Although the case where the focus lens holding frame 3 is moved by the lead screw 10 has been described, the present invention is not limited to the focus lens as long as the lens holding frame is moved in the optical axis direction.

Further, the lead screw 10 is formed on the shaft of the pulse motor 9 and the lead screw 10 and the shaft are described as being integrated. However, the present invention is not limited to this. May be separately driven and connected, and the lead screw 10 may be rotated when the pulse motor 9 is driven.

[0028]

According to the present invention , the present invention is constituted as in claim 1.
As a result, the number of parts
Can be done. Therefore, the manufacturing cost
It can be lowered. The rack and lead screen
Because it will be engaged with the press in the pressed state,
The parallelism between the lead screw and the guide shaft is slightly
However, the deviation can be absorbed. I
As a result, assembly becomes easier,
The manufacturing cost can be reduced. further,
The rack and the lead screw are positioned between the center of the guide hole and the light
Meshingly engaged at a position shifted from the extension of the line connecting the shaft
Therefore, the lens holding frame has a direction perpendicular to the optical axis.
(The direction of rotation about the center of the guide hole)
This force causes the inner surface of the U-shaped groove to
Will be pressed against the surface of the shaft. Therefore,
Direction perpendicular to the optical axis of the lens holding frame (center of the guide hole
Backlash in the direction of rotation about the center)
When the lens holding frame moves along the guide axis
Of the optical axis can be prevented.

Further , according to the second aspect of the present invention,
The thinner, which is elastically engaged with the lead screw,
The wear of the rack of the plate-like projections can be prevented.
And can improve the durability, stable over the long term
The lens holding frame can be moved along the guide axis
Will be.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a lens driving device according to the present invention.

FIG. 2 is a schematic view showing a state in which a lead screw and a rack portion of a thin plate-like projection provided on a lens holding frame are elastically engaged with each other.

FIG. 3 is a schematic perspective view showing a conventional lens driving device.

FIG. 4 is a schematic perspective view showing another conventional lens driving device.

[Explanation of symbols]

 1, 2, 21, 22, 41, 42 ... guide shafts 3, 23, 43 ... focus lens holding frames 4, 24, 44 ... sleeve portions 4a, 4b ... projecting portions 5a, 5b, 25, 45 ... ... Guide holes 6, 26, 46 ... U-shaped groove 8 ... Thin plate-shaped projections 9, 29, 49 ... Driving source 10, 30, 50 ... Lead screws 11, 31, 51 ... Rack parts 13, 33 , 53... U-shaped bracket 14... Mounting holes 27, 47... Connection shafts 28, 48... Connection frames 32, 52... Pressing portions 54. axis

Claims (2)

(57) [Claims] A guide hole facing the optical axis and a U-shaped groove;
And a lens holding frame that is provided in parallel with the optical axis.
Through the guide hole and the U-shaped groove to hold the lens.
A guide shaft movably supporting the frame, and the lens holding frame
To the direction perpendicular to the optical axis.
A sheet-like projection that can be sexually displaced;
Rack part provided on the body and provided substantially parallel to the optical axis
And a lead engaged with the rack portion in a pressed state.
And the lead screw is rotationally driven.
A drive source, the rack part and the lead screw
Are on the extension of the line connecting the center of the guide hole and the optical axis.
A lens driving device characterized in that the lens driving device is configured to be engaged at a shifted position . 2. The method according to claim 1, wherein said thin plate-like projection is made of a lubricating material.
The lens driving device according to claim 1.