JPH0932902A - Mechanism for linear movement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism for linear movement with which a member to be moved can be moved smoothly and without being inclined while an installation space can be reduced. SOLUTION: A male thread part 31a and a cylindrical part 31b are formed on an outer peripheral surface of a screw shaft 31 and in pallel with a shaft center line, while a female thread part 4c threadedly engaged with the male thread part 31a and a fitting part 4d, which is fitted to an outside of the cylindrical part 31b, are formed in an inner peripheral surface of a cylindrical part 4B, which is provided so as to be connected to a holder 4A of a compensator lens group 4. A spring 32 installed between the cylindrical part 4B and a lens- barrel 2 energizes the screw shaft 31 toward a shaft supporting hole 2b of the lens-barrel 2. When the rotation of a motor 11 rotates the screw shaft 31 via a driving gear train 6, the cylindrical part 4B is guided/moved through sliding/contact between the fitting part 4d and the cylindrical part 31. Thus, the compensator lens group 4 can be moved in the direction of an optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a case where a lens is moved along an optical axis in a camera or a magnetic recording head is moved in a radial direction of a magnetic disk in a magnetic recording device by rotating a motor. Relates to a straight-ahead mechanism used in

More specifically, the driven member is provided along a straight path on each of the driven member side such as the lens and the magnetic head described above and the fixed portion side where the movement of the driven member along the moving direction is prohibited. A drive mechanism that forms a sliding contact surface that movably supports the movable member and moves the driven member along the linear path by relative rotation of the screw shaft in the posture along the linear path and the nut body screwed to the screw shaft. The present invention relates to a straight traveling mechanism.

[0003]

2. Description of the Related Art A conventional linear moving mechanism of this type will be described with reference to FIG.

This rectilinear mechanism is used for a zoom lens, and is a compensator lens (03) for focus adjustment.
Is linearly moved in the optical axis (L) direction.

The compensator lens (0
The protrusion (0) formed on one end side of the holder (03A) of 3).
3B ') includes a fitting portion (03b') and a female screw portion (03
x) and are formed. A guide shaft (5 ′) having an attitude along the moving straight line path of the compensator lens (03) is fitted in the fitting portion (03b ′). In addition, the female screw portion (03x) also has a compensator lens (0
The screw shaft (5 ″) having a posture along the moving linear path of 3) is screwed.

The guide shaft (5 ') is fixed to the lens barrel (2) which is a fixed portion. Also, the screw shaft (5 ")
Is rotatably supported by the lens barrel (2). Further, the lens barrel (2) has a detent shaft that is loosely fitted in a U-shaped groove (03a) on the other end side of the holder (03A) of the compensator lens (03) to prevent rotation of the compensator lens (03). (12) is fixed.

A part of the screw shaft (5 ") has a gear (6).
A) is attached to the screw shaft (5 ″) so as to rotate integrally therewith, and a drive gear (6B) interlockingly coupled with the motor (7) meshes with the gear (6A) to form a drive gear train (6). I am configuring.

Then, the screw shaft (5 ") is rotated by the rotation of the motor (7), and the projecting portion (03B ') of the holder (03A) screwed to the screw shaft (7") is connected to the guide shaft (5B). The compensator lens (03) can be moved by moving the compensator lens (03) along the optical axis (L) while being guided by 5 ').

That is, the protrusion (03) of the holder (03A)
The inner peripheral surface of the fitting portion (03b ') formed in B') and the outer peripheral surface (5b ') of the guide shaft (5') pass through the compensator lens (03), which is a driven member, along a straight path. A sliding contact surface that movably supports it. Further, the overhanging portion (03B ') of the holder (03A) having the female screw portion (03x) screwed onto the screw shaft (5 ") constitutes a nut body.

Further, the motor (7), the drive gear train (6), the screw shaft (5 "), and the overhanging portion (03B ') of the holder (03A) pass the compensator lens (03) along a straight path. And a drive mechanism (DM ') for moving it.

[0011]

However, in the case of the above-mentioned conventional structure, a screw shaft for drivingly moving the driven member by the motor and a guide shaft for guiding the movement of the driven member are separately provided. Because they were 2
This requires a large installation space for the three shafts, which hinders downsizing of a device having this type of straight path.

In particular, when there are a large number of driven members such as an optical device, for example, a lens having a zoom function and a focus adjusting function, the screw shaft for each driven member can be obtained by the conventional structure as described above. Since it is necessary to provide the guide shaft and the guide shaft, the lens becomes bulky and the assembly becomes complicated with an increase in the number of parts, resulting in an increase in the cost of the product.

Further, since the screw shaft and the guide shaft are provided at different positions in the direction orthogonal to the straight line path along which the driven member moves, the screw shaft and the guide shaft are brought into contact with the sliding contact surface on the driven member side as the driven member moves. Inclination easily occurs between the sliding contact surface on the fixed portion side or between the screw shaft and the nut body, and it is difficult to smoothly move the driven member.

In view of the above situation, an object of the present invention is to provide a rectilinear mechanism capable of smoothly moving a driven member without causing an inclination and reducing the installation space.

[0015]

A linear movement mechanism according to the present invention includes a screw shaft having a male screw portion and a sliding contact surface formed by axially different positions of the male screw portion, and the screw. A nut body having a female screw portion that is screwed into the male screw portion of the shaft and a sliding contact surface that is formed at a position different from the female screw portion and that is in sliding contact with the sliding contact surface of the screw shaft; The screw shaft and the nut body are relatively rotated in a state where the parts are screwed together and the sliding contact surfaces are in contact with each other, so that the sliding contact surfaces are slidably contacted with each other in the screw axis direction. It is characterized in that the shaft or the nut body is moved along a straight path.

[0016]

In the nut body and the screw shaft which form the straight-moving mechanism, the male screw portion of the screw shaft and the female screw portion of the nut body are screwed together, and the nut body and the screw shaft are provided at positions different from the screw portions. The sliding contact surfaces are engaged with each other. Then, when the screw shaft and the nut body rotate relative to each other, the screw shaft or the nut body moves along a straight line path while the respective sliding contact surfaces are in sliding contact with each other in the screw axis direction.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a schematic cross section of a video camera having a zoom lens provided with a rectilinear mechanism according to the present invention.

The front lens group (1) of this zoom lens is fixed to the front end of the lens barrel (2). Behind this front lens group (1), a variator lens group (3) that moves back and forth along the optical axis (L) to continuously change the focal length of the zoom lens,
A compensator lens group (4) is also provided which moves back and forth along the optical axis (L) to adjust the focus of the zoom lens.

The variator lens group (3) has an optical axis (L).
The variator drive shaft (5) is rotatably supported by the lens barrel (2) in a posture along the axis, and as will be described later, by rotating the variator drive shaft (5), the optical axis (L) Is configured to move along. The variator drive shaft (5) is connected to the drive gear train (6).
The motor (7) for the variator is interlocked and connected via.

A brush (8) for position detection is attached to the variator lens group (3). The brush (8) slides on a zoom encoder (9) provided in a posture along the optical axis (L) as the variator lens group (3) moves along the optical axis (L). Is configured.

The compensator lens group (4) is
The compensator drive shaft (10) is rotatably supported by the lens barrel (2) in a posture along the optical axis (L), and as described later, by rotating the compensator drive shaft (10), It is configured to move along the optical axis (L). And, this compensator drive shaft (1
0) is interlocked with a compensator motor (11) via a drive gear train (not shown).

In order to prevent the rotation of the variator lens group (3) and the compensator lens group (4) due to the movement, a U-shape formed at one end of each of these two lens groups (3), (4). A rotation stop shaft (12) loosely fitted in the grooves (3a) and (4a) is fixed to the lens barrel (2).

A half prism (13) is provided behind the compensator lens group (4). Most of the light flux from the subject is the half prism (1
3) goes straight ahead, passes through a master lens group (14) and a low-pass filter (15) provided behind it, and then is guided to a CDD (16) for imaging. .

The rest of the bundle of rays from the subject is bent in its optical path by the half prism (13), passes through the total reflection mirror (17) and the distance measuring lens (18), and then in the distance measuring module (19). It is configured to be guided to the CCD line sensor (19a) for automatic focus adjustment.

In order to move the above-mentioned variator lens group (3) and compensator lens group (4) along the optical axis (L) by driving the motor (7) and motor (11), respectively, A straight-ahead mechanism according to the invention is used. Since they have the same configuration, only the rectilinear mechanism for moving the variator lens group (3) will be described below.

As shown in FIG. 1, a variator drive shaft (5) is pivotally supported on the lens barrel (2). The gear (6A) fixed to the variator drive shaft (5) meshes with the drive gear (6B) interlockingly connected to the motor (7). That is, the drive gear train (6) is configured by the gear (6A) and the drive gear (6B).

The variator drive shaft (5) is pressed by the spring (20) into the shaft support hole (2a) of the lens barrel (2) on the left side in the figure, so that there is no play in the axial direction. It is configured.

On the outer peripheral surface of the variator drive shaft (5), a spiral V-shaped groove (5a) is formed over substantially the entire length, and the portion other than the V-shaped groove (5a) is variator. It is formed on a cylindrical surface (5b) whose axis of rotation is the axis (X) of the drive shaft (5).

That is, this variator drive shaft (5) is
It is formed on a screw shaft having the character-shaped groove (5a) as a screw groove and the cylindrical surface (5b) as a top of a screw thread.

Then, on the variator drive shaft (5),
A cylindrical portion (3B) continuously provided at one end of a holder (3A) of the variator lens group (3) is externally fitted. The diameter of the inner peripheral surface (3b) of the tubular shape (3B) is the same as the cylindrical surface (5b).
The cylindrical portion (3B) is formed to have a diameter substantially equal to the outer diameter of, and as shown in the drawing, the cylindrical portion (3B) has a length corresponding to a plurality of threads with the cylindrical surface (5b) as the top. Have

A ball body (21) fitted in the V-shaped groove (5a) is attached to the tubular portion (3B). The ball body (21) is fitted in a hole (22a) formed in a leaf spring (22) fixed to the tubular portion (3B) and having a diameter smaller than that of the ball body (21).
Due to the biasing force of the leaf spring (22), the V-shaped groove (5a)
The variator drive shaft (5) pressed against the side
In a state where movement of the ball body (21) in the radial direction, the circumferential direction, and the axial center (X) direction is restricted, only rotation about the center of the ball body (21) is allowed.

Then, by rotating the zoom motor (7), the variator drive shaft (5) is rotated around its axis (X) through the drive gear train (6), and the ball body (21) is moved. As the variator drive shaft (5) rotates, the variator drive shaft (5) is driven according to the lead of the V-shaped groove (5a), so that the tubular portion (3B) moves along the optical axis (L), and thereby the driven portion is moved. The variator lens group (3), which is a member, moves along a linear path parallel to the optical axis (L).

At this time, the inner peripheral surface (3b) of the cylindrical portion (3B) is in sliding contact with the cylindrical surface (5b) of the variator drive shaft (5), and there is no eccentricity, inclination, or rattling. , The variator drive shaft (5) is guided and moved in the axial center (X) direction.

That is, the inner peripheral surface (3b) of the tubular portion (3B) is a sliding contact surface on the side of the variator lens group (3) which is a driven member, and the cylindrical surface (5b) of the variator drive shaft (5) is. It is a sliding contact surface on the side of the lens barrel (2) which is a fixed portion, and these two sliding contact surfaces (3b), (5b) support the variator lens group (3) movably along a linear path. There is.

Further, the ball body (21) and the leaf spring (22)
A tubular portion (3B) having and is a nut body screwed to a variator drive shaft (5) which is a screw shaft, and includes a motor (7), a drive gear train (6), a variator drive shaft (5),
And, the tubular portion (3B) is a variator drive shaft (5) which is a screw shaft, and a tubular portion (3 which is a nut body screwed to the variator drive shaft (5).
A drive mechanism (D) for moving the variator lens group (3), which is a driven member, along a linear path by relative rotation with respect to (B).
M).

Then, the screw forming portion of the variator drive shaft (5) which is the screw shaft, that is, the portion where the V-shaped groove (5a) is formed, extends over substantially the entire length of the circumference of the sliding contact surface on the fixed portion side. By forming the surface (5b), it is possible to make the working axis of the variator lens group (3) large and also to serve as the driving axis and the guiding axis, so that the variator lens group (3) can move. The inclination of time is reduced and the space is saved.

Further, the ball body (21) has a spring (2
Since it is pressed to the V-shaped groove (5a) side by the urging force of 2), even if there is some manufacturing error in the V-shaped groove (5a), there is no rattling regardless of the error. The variator lens group (3) can be moved with. As a result, it is possible to allow the variator drive shaft (5) to have a sufficient manufacturing accuracy, and it is possible to achieve cost reduction due to an increase in manufacturing efficiency.

The ball body (21) is pressed against the V-shaped groove (5a) by the urging force of the spring (22), the spring (22) is omitted, and the ball body (21) is simply rotatable. It may be attached to the tubular portion (3B).

Further, instead of the V-shaped groove (5a) as a screw groove, a groove having a U-shaped or U-shaped or trapezoidal cross section is formed on the outer peripheral surface of the variator drive shaft (5). May be.

FIG. 3 shows another embodiment of the rectilinear mechanism according to the present invention. This embodiment has a configuration for moving a magnetic head (23) for magnetic recording in a magnetic recording apparatus or the like.

In this embodiment, the gear (6A) that meshes with the drive gear (6B) on the motor (24) side is a ball body (21) and a leaf spring (22) having the same construction as in the previous embodiment.
Although not shown, the cylindrical body (2) whose movement in the left-right direction in the figure is restricted by contact with the frame (25) (not shown)
It is formed on the outer peripheral portion of 6). The screw shaft (27) formed in the same manner as in the previous embodiment is non-rotatable, and
A frame (25) is movably supported in the left-right direction in the figure, and a magnetic head (23) is fixed to the screw shaft (27).

Then, by rotating the motor (24), the cylindrical body (26) is rotated via the drive gear train (6), and the ball body (21) is restricted from moving in the horizontal direction in the figure. Screw shaft (27) along with rotation of the tubular body (26)
By rolling along the V-shaped groove (27a), the screw shaft (27) moves in the left-right direction in the figure. As a result, the magnetic head (23), which is a driven member, moves along a linear path parallel to the axis (X) of the screw shaft (27).

At this time, the screw shaft (27) has a cylindrical surface (27b) formed in a portion other than the V-shaped groove (27a).
Is brought into sliding contact with the inner peripheral surface (26a) of the tubular body (26) to be guided and moved.

That is, the cylindrical surface (27b) of the screw shaft (27)
Is a sliding contact surface on the side of the magnetic head (23) which is a driven member, and an inner peripheral surface (26a) of the tubular body (26) is a sliding contact surface on the side of the frame (25) which is the fixed portion. Also, a tubular body (26) having a ball body (21) and a leaf spring (22).
Is a nut body screwed onto the screw shaft (27). Further, the motor (24), the drive gear train (6), the tubular body (2)
6) and the screw shaft (27) form a drive mechanism (DM).

That is, the sliding contact portion formed on the screw forming portion of the screw shaft may be the driven member side or the fixed portion side.

4 to 6 show still another embodiment of the rectilinear mechanism according to the present invention. This embodiment is similar to the embodiment shown in FIG. 3 and has a magnetic head (23).
It is a structure for moving.

In this embodiment, the screw shaft (28)
Has a linear groove (28A) along its axial direction, and a normal screw thread and a thread groove are formed in a portion other than the linear groove (28A). And this screw shaft (2
Similar to the embodiment shown in FIG. 3, 8) shows the frame (25) in a state in which it cannot be rotated and is movable in the left-right direction in the drawing.
The magnetic head (23) is fixed to the screw shaft (28).

As shown in FIGS. 4 and 5, a gear portion (6A) is formed on the outer peripheral surface of the nut body (29) screwed onto the screw shaft (28). 6A)
Is a drive gear (6B) linked to the motor (24)
To form a drive gear train (6).

A guide ring (30) is rotatably attached to the nut body (29) with respect to the nut body (29). The diameter of the inner peripheral surface of the ring (30) is larger than the outer diameter of the male screw of the screw shaft (28). A projection (30A) is formed on the inner peripheral surface of the ring (30) as shown in FIG. 6, and the outer peripheral surface (30a) of the projection (30A) is formed on the screw shaft (28).
The linear groove (28A) and the protrusion (30A) are fitted in a state of slidingly contacting the inner peripheral surface (28a) of the linear groove (28A).

The arm (30B) of the ring (30) is fixed to the frame (25), and the ring (30) is
In FIG. 4, it is configured such that it cannot move in the left-right direction and cannot rotate.

Then, by rotating the motor (24), the nut body (29) is rotated, and accordingly, the screw shaft (28) is moved in the left-right direction in the figure by screwing with the nut body (29). To do. As a result, the magnetic head (23), which is a driven member, moves along a linear path parallel to the axis of the screw shaft (28).

At this time, the inner peripheral surface (28a) of the linear groove (28) of the screw shaft (28) is in sliding contact with the outer peripheral surface (30a) of the protrusion (30A) of the ring (30) in the positionally fixed state. By doing so, you will be guided and moved.

That is, the straight groove (28A) of the screw shaft (28)
The inner peripheral surface (28a) of the magnetic head (2
3) side sliding contact surface, and the protrusion (30) of the ring (30).
The outer peripheral surface (30a) of (A) is a frame (2
5) The sliding contact surface on the side. Then, the motor (24), the drive gear (6B), the nut body (29) with the gear portion (6A),
The ring (30) constitutes a drive mechanism (DM).

FIG. 7 shows still another embodiment.
This embodiment is different from the embodiment shown in FIG. 1 above in that the compensator lens group (4) is moved by a smaller amount than the variator lens group (3).
Although the compensator lens group (4) is depicted as a single-lens configuration in this drawing, the configuration of the compensator lens group (4) itself can be changed as appropriate.

In this embodiment, a male screw portion (31a) and a cylindrical portion (31b) are formed on the outer peripheral surface of the screw shaft (31) side by side in the axial direction of the screw shaft (31). On the other hand, a female screw portion (4c) screwed to the male screw portion (31a) and the cylinder are formed on the inner peripheral surface of a cylindrical portion (4B) connected to the holder (4A) of the compensator lens group (4). A fitting portion (4d) is formed so as to be externally fitted in a state of slidingly contacting the portion (31b). In addition, the cylindrical portion (4B) and the lens barrel (2)
A spring (32) is installed between the screw shaft and the screw shaft (3) by the urging force of the spring (32).
1) is pressed against the shaft support hole (2b) of the lens barrel (2) on the right side in the figure.

Then, by rotating the motor (11), the screw shaft (31) is rotated via the drive gear train (6), and accordingly, the tubular portion (4B) is fitted into its fitting portion ( 4d) and the cylindrical part (31b) of the screw shaft (31) are guided and moved by sliding contact. This causes the compensator lens group (4), which is a driven member, to move along a straight line path parallel to the optical axis (L).

In each of the above-described embodiments, the structure for moving the lenses (3) and (4) in the zoom lens and the structure for moving the magnetic head (23) in the magnetic recording apparatus are taken as examples. Although described, the rectilinear mechanism according to the present invention can be implemented for various devices such as a structure for moving a print head in various printers or a structure for moving a pen in a plotter. .

[0059]

As described above, in the straight-moving mechanism of the present invention, the screw shaft for moving the nut body is formed with the sliding contact surface for guiding the movement of the nut body. The required guide shaft can be omitted, and the installation space can be made smaller and the weight can be reduced accordingly. Further, the number of assembling steps can be reduced and the cost can be reduced.

Further, since the nut body is guided by the screw shaft itself, the nut body can be moved smoothly without inclination. Particularly, since the screw portion and the sliding contact surface are provided apart from each other in the moving direction of the nut body, it is possible to effectively prevent the nut body from tilting. For this reason, it is possible to reduce the size and weight of the motor and reduce the cost thereof without giving unnecessary load to the motor that constitutes the drive mechanism.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a rectilinear mechanism.

FIG. 2 is a schematic cross-sectional view of the inside of a zoom lens of a video camera using a rectilinear mechanism.

FIG. 3 is a vertical sectional view corresponding to FIG. 1 showing another embodiment.

FIG. 4 is a longitudinal sectional view corresponding to FIG. 1 showing still another embodiment.

5 is a cross-sectional view taken along line VV in FIG.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a vertical sectional view showing still another embodiment.

FIG. 8 is a longitudinal sectional view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

(3), (23) ... driven member (2), (25) ... fixed part (3b), (5b), (26a), (27a), (28
a), (30a) ... sliding surface (5), (27), (28) ... screw shaft (3B), (26), (29) ... nut body (5b) ... cylindrical surface (5a) ), (27a) …… Screw groove (21) …… Ball body (22) …… Spring (X) …… Screw shaft core (DM) …… Drive mechanism

Claims (3)

[Claims] 1. A screw shaft having a male screw part and a sliding contact surface formed by axially different positions of the male screw part, and a female screw screwed with the male screw part of the screw shaft. And a nut body that is formed at a position different from the female screw portion and has a sliding contact surface that slides in contact with the sliding contact surface of the screw shaft. By relatively rotating the screw shaft and the nut body in a state where the surfaces are in contact with each other, the screw shaft or the nut body along a straight path while slidingly contacting each of the sliding contact surfaces in the screw axis direction. A straight-ahead mechanism characterized by being moved. 2. The rectilinear mechanism according to claim 1, wherein the sliding contact surface of the nut body has a cylindrical shape that fits with the screw shaft. 3. The rectilinear mechanism according to claim 1, further comprising a biasing unit that biases at least one of the nut body and the screw shaft toward the other.