JPH0410603Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) The present invention relates to a drive device that moves a lens group forward and backward in order to change the magnification of a zoom lens for a copying machine. The present invention relates to a driving device for a zoom lens for a copying machine, in which a zoom lens for a copying machine is directly driven by engagement between a motor disposed on the lens holder and a guide member of the main body of the device.

(Prior art) Generally, the driving methods for moving a zoom lens for a copying machine forward and backward in the optical axis direction include a method in which a cam cylinder is used to drive part or all of the optical system, and a method in which a pulley and wire are used to drive the lens system. , a method in which a motor is placed on a lens system carrier and the entire optical system is driven using a motor pinion and a dedicated rack is known.

Among these, JP-A No. 59-94708 is known as a drive system for motor pinion and rack.
In this method, the lens holder is provided with a shaft that guides forward and backward movement in the direction of the optical axis, a driving motor is placed on the lens holder, and a rack as a movement transmission means is placed in relation to this motor. This is a zoom lens drive mechanism in which a shaft as a guide in the optical axis direction with respect to a lens holder and a rack engaged with a motor for forward and backward movement are constructed as separate members.

(Problems to be solved by the invention) With these conventional methods, the cam cylinder has problems such as manufacturing cost and large drive system, while the pulley and wire method has assembly and manufacturing costs due to wire attachment, etc. The conventional method of driving the motor pinion and rack has drawbacks such as using a dedicated shaft as a guide rod to guide the lens holder, and the transmission mechanism from the motor to the rack is complicated. It was hot.

The present invention is an improvement on the conventional method in which a motor is placed on the lens system carrier and the entire optical system is driven using a motor pinion and a dedicated rack, simplifying the mechanism and reducing the number of transmission members as much as possible. According to
The purpose is to prevent backlash and improve accuracy.

(Structure of the present invention) The driving device of the zoom lens for a copying machine of the present invention is as follows:
By configuring the guide surface as an optical reference surface of the lens carrier and the rack, which is a drive system for moving the lens carrier forward and backward, into a single guide member, mechanical errors such as backlash can be reduced.
This is a zoom lens that can easily achieve standard positional accuracy.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

4 and 2 are plan views and main parts of the drive device for a zoom lens for a copying machine according to the present invention, in which a guide member 4 for corner registration is arranged in the main body 1, A lens carrier 3 carrying a zoom lens group 2 is attached so as to be able to move forward and backward along the guide member 4 in the optical axis direction.

The lens carrier 3 supports a zoom lens group 2, and the zoom lens group 2 engages with the cam barrel 2a of the zoom lens group 2 as the lens carrier 3 moves back and forth along the guide member 4. The cam guide rod 5 displaces a part of the lens interval of the lens system to change the magnification, and the configuration for changing the magnification in this manner is well known.

The lens carrier 3 is provided with a drive motor 6 for moving forward and backward with respect to the guide member 4.
As shown in FIG. 2, the gear 6a of the drive motor 6
is engaged with the rack 4b of the guide member 4, and the reference surface 3b of the lens carrier 3 is engaged with the guide surface 4b of the guide member 4.
Further, a pressing member 7 is attached to the lens carrier 3, and this pressing member 7 prevents the engagement between the gear 6a and the rack 4b and the contact between the reference surface 3b and the guide surface 4a. This is to ensure that
The guide member 4 is sandwiched between the pressing member 7 and the reference surface 3b. In particular, by forming the pressing surface of the pressing member 7 with a roller or a material with low friction, the lens carrier 3 can be moved forward and backward. Can be done accurately and smoothly.

The drive motor 6 is configured so that its mounting position can be slightly changed in order to adjust the distance between the gear 6a and the rack 4b, and allows the lens holder 3 to move smoothly.

The drive motor 6 is rotated by a predetermined amount by setting the magnification, and the lens carrier 3 is moved from a starting position (not shown) along the guide member 4 to a position where the predetermined magnification is achieved. Furthermore, the distance between some lenses of the optical system of the zoom lens group 2 is changed by a guide rod 5 arranged at an angle with respect to the moving direction of the lens carrier 3, so that a predetermined magnification is achieved.

Corner registration is a mechanism often used in zoom lenses for copying machines, and is a mechanism that allows the copying machine to set the document placement position based on one end of the document or a corner of the document even if the copy size changes. This is solved by moving the lens group in a direction that has a predetermined angle with respect to the optical axis depending on the size of the original or the magnification of reduction/enlargement. A corner resist guide member guides at an angle to the optical axis.

(Effects of the present invention) The direction in which the guide surface of the guide member faces the reference plane of the lens carrier is the same as the direction in which the rack of the guide member faces the motor for driving the lens carrier. is possible, and there is less mechanical interference between the guide surface and the drive motor, making it easier to achieve positional accuracy.

Furthermore, a common pressing member can be used for the structure that transmits the driving force between the drive motor and the rack of the guide member and the structure of the reference surface that supports the lens carrier at a reference position. Since the members can be pressed in the same direction, the mechanism can be simplified and mechanical accuracy can be improved compared to conventional methods.

Furthermore, by sharing the guide member for corner registration used in the zoom lens for copying machines as the guide member that supports the lens carrier, the mechanism is further simplified and the reference surface is achieved by eliminating the intermediate transmission part. It is possible to improve the accuracy for

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of a driving device for a zoom lens for a copying machine according to the present invention, and FIG. 2 is a perspective view showing essential parts of the embodiment shown in FIG. 2...zoom lens group, 3...lens carrier,
4... Corner resist guide member, 4a...
Guide surface, 4b... Rack, 5... Cam guide rod, 6... Drive motor, 6a... Gear, 7... Pressing member.

Claims (1)

[Scope of utility model registration request] In a drive device for a zoom lens for a copying machine, which changes magnification by changing the interval between lenses in a part of an optical system by moving back and forth a lens carrier carrying a lens group, a reference plane is formed on the lens carrier. At the same time, a drive motor for forward and backward movement and a pressing member are provided at a position opposite to the reference surface, and a rack portion and a guide surface are formed on the reference surface side, and a guide member for guiding the lens carrier is provided. The rack portion is disposed between a reference surface and the pressing member, and the gear provided on the drive motor is engaged with the rack portion, and the reference surface and the guide surface are brought into contact with each other, so that the guide member is moved. A zoom lens driving device for a copying machine, characterized in that it is pressed by the pressing member.