JP2894759B2 - Lens drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device that can be used for a photographic lens for a video camera and the like.

2. Description of the Related Art In recent years, with the spread of video cameras, the demand for photographing lenses has rapidly increased, and demands for further miniaturization have increased. Attempts have been made to reduce the size of the lens barrel holding the lens and to improve the stable operation. Hereinafter, an example of a conventional lens driving device will be described with reference to the drawings. FIG. 6 is a sectional view of a conventional lens barrel, and FIG. 7 is an enlarged sectional view of a main part thereof. In the drawing, reference numeral 1 denotes a lens barrel main body, and the main body 1 is a lens constituting the objective lens group 5.
2, 3, and 4 are fixed at predetermined positions. Reference numeral 6 denotes a spacer between the lenses 3 and 4, and reference numeral 7 denotes a holding nut for the objective lens group 5.
Reference numeral 8 denotes a third group frame that is coupled to the main body 1, and a lens 9 is fixed to the third group frame 8. Reference numeral 10 denotes a guide pole provided between the main body 13 and the group frame 8, on which the two-group moving frame 11 holding the lenses 12, 13, and 14 constituting the variable power lens group 15 slides. It is provided as follows. Reference numeral 16 denotes a screw shaft provided between the main body 1 and the third group frame 8 in the same manner as the guide pole 10, meshes with the second group moving frame 11, and the second group moves by rotating the screw shaft 16. The frame 11 is configured to be movable in the direction of the optical axis 17. Reference numeral 18 denotes a gear unit integrally fixed to the screw shaft 16, and 19 denotes a motor unit. The motor unit 19 is fixed to the main body 1 so as to mesh with the gear unit 18 of the screw shaft 16, and is controlled by a control signal. Then, the second group moving frame 11 is moved by rotating the screw shaft 16. Although only a part is shown, reference numeral 20 denotes an iris unit that performs an aperture operation by a control signal. Reference numeral 21 denotes a master flange fixed to the third group frame 8;
A plurality of guide poles 22 are provided between 21 and the third group frame 8. Reference numeral 23 denotes a four-group moving frame supported by a guide pole 22, and the fourth-group moving frame 23 fixes lenses 24, 25, and 26 constituting a focus lens group 27. A focus motor 28 is fixed to the master flange 21. A nut 29, which is not rotated (not shown), is slidably attached to a shaft 28 a of the focus motor 28, and a lower end of the nut 29 is engaged with an engaging portion 23 at an upper end of the fourth group moving frame 23.
is engaged with a. With this configuration, when the focus motor 28 is rotated by the control signal, the
The group moving frame 23 operates in the optical axis direction. Further, the main body 1, the third group frame 8, the master flange portion
The reference numeral 21 forms the outer frame of the lens barrel. Although the operation of the lens barrel described above does not show a change in the variable power lens group 15, it is detected by position detection means, and the focus lens group 27 is operated by the detection signal, and a predetermined predetermined It moves to a position to focus.

In the above configuration, when the shaft 28a of the focus motor 28 rotates and the nut 29 moves in the direction of the arrow A as shown in FIG. Can not do. That is, the fourth group movement caused by the engagement between the guide pole 22 and the fourth group moving frame 23 or the separation between the position of the guide pole 22 and the engagement portion between the fourth group moving frame 23 and the nut 29. The rotation of the frame 23 in the direction of arrow B occurs instantaneously when the nut 29 is activated. For this reason, the movement of the focus motor 28 is not correctly reflected on the movement of the fourth-group moving frame 23, and the camera is out of focus at the time of startup.

An object of the present invention is to solve such a problem, and an object of the present invention is to enable the movement of a motor to be correctly transmitted to a moving frame.

Means for Solving the Problems To solve this problem, the present invention provides an outer frame of a lens barrel having a plurality of lenses, wherein the optical axis direction and the axial direction of the plurality of lenses are arranged in parallel. A guide pole supported by an outer frame of the lens barrel and inside the lens barrel;
A moving frame movably fitted to the guide pole and holding the plurality of lenses; a motor fixed to an outer frame of the lens barrel and outside the lens barrel; and an optical axis of the plurality of lenses. A nut slidably engaged with the shaft of the motor, the direction of which is arranged in parallel with the axis direction, and an extension extending from the nut in the load direction of the guide pole,
A substantially arc-shaped projection provided so as to protrude from the extending portion in the axial direction of the guide pole, and provided on the moving frame in a direction substantially orthogonal to the axial direction of the guide pole; An engagement portion, wherein the engagement portion and the projection are engaged on a side of an axis of the guide pole substantially perpendicular to a load direction of the guide pole.

Operation With this configuration, when the nut is operated by the rotation of the motor, there is no stick-slip of the moving frame holding the lens group, and the rotation of the motor can be accurately transmitted to the moving frame via the nut. It is possible to prevent momentary defocusing at the time of startup.

Example Hereinafter, an example of the present invention will be described with reference to the drawings (first to fifth examples).
Explanation will be made based on FIG. In the drawings, the same reference numerals as those in the conventional example denote the same members, and a detailed description thereof will be omitted.

In the figure, reference numeral 30 denotes an engagement portion with a nut 29 provided on the upper part of the fourth group moving frame 23, which is provided near the side of the guide pole 22 supporting the fourth group moving frame 23. . Numeral 31 denotes hemispherical projections for engagement provided on both front ends of the nut 29, which are in contact with the engagement portions 30 of the fourth group moving frame 23 so as to be sandwiched from front and rear. In the present embodiment, the protrusion 31 is provided at one end of the nut 29 so as to be located on one side of the guide pole 22, but is provided at both sides of the guide pole 22 and is associated with the fourth group moving frame 23. You may make it match. Other configurations are the same as those of the conventional example.

In the above configuration, the engaging portion 30 of the fourth group moving frame 23 and the nut
Since the projections 31 of 29 are engaged on the sides of the guide pole 22, the fourth group moving frame which is to be generated by the operation of the nut 29
It is possible to prevent the occurrence of the 23 state slips.

Effects of the Invention As described above, according to the present invention, there is no stick-slip of the moving frame holding the lens group during the operation of the nut due to the rotation of the motor, and the rotation of the motor is accurately transmitted to the moving frame via the nut. , And instantaneous defocusing at the time of starting the motor can be prevented.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the lens barrel, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is a perspective view of a main part of a fourth group moving frame, FIG. FIG. 6 is a cross-sectional view of the main part of FIG. 6, FIG. 6 is a cross-sectional view of a conventional lens barrel, and FIG. 7 is an enlarged view of the main part of FIG. 1 ... Main body of lens barrel, 2,3,4 ... Lens, 5 ... Objective lens group, 8 ... 3 group frame, 9 ... Lens, 10 ... Guide pole, 11 ... 2 group moving frame , 12,13,14 …… Lens, 15
…… magnification lens group, 16 …… screw axis, 17 …… optical axis, 18 ……
Gear part, 19 Motor part, 20 Iris part, 21 Master flange part, 22 Guide pole, 23 Four-group moving frame, 24, 25, 26 Lens, 27 Focus Lens group, 28 Focus motor, 28a Shaft, 29
… Nut, 30… engagement part, 31 …… projection.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-265215 (JP, A) JP-A-62-47609 (JP, A) JP-A 62-118215 (JP, U) JP-A 58- 91709 (JP, U) Shokai 51-3339 (JP, U) Shokai 2-1216 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 7/04 G02B 7 / 08

Claims (1)

(57) [Claims] 1. An outer frame of a lens barrel having a plurality of lenses, and an optical axis direction and an axial direction of the plurality of lenses are arranged in parallel with each other. A guide pole supported on the inside, a moving frame movably fitted to the guide pole and holding the plurality of lenses, and a motor fixed to an outer frame of the lens barrel and outside the lens barrel And a nut slidably engaged with a shaft of the motor in which the optical axis direction and the axis direction of the plurality of lenses are arranged in parallel, and an extension extending from the nut in a load direction of the guide pole. Part, a substantially arc-shaped projection provided so as to protrude from the extending portion in the axial direction of the guide pole, and in a direction substantially orthogonal to the axial direction of the guide pole provided on the moving frame. And an engaging portion provided. In the guide side of the axis of the pole that is substantially orthogonal to the load direction of the pole, the lens driving device, characterized in that it engages with said projection and said engaging portion.