JPH04309909A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To provide the small-sized, lightweight zoom lens barrel. CONSTITUTION:Zoom constitution mentioned below is employed so as to attain the purpose. Namely, a feed screw and rack constitution are used to move a variator frame 4. A compensator frame 6 is moved by rotating a control member 17 which controls the position of a compensator frame 6 through a gear 11 fitted coaxially with the feed screw. Consequently, a cam ring and a cam follower which are necessary before can be removed and the outward shape of the zoom lens barrel is made small by the quantity of occupation of the above removed elements. Thus, the zoom lens is reducible in size and also reduced in weight by the quantity of reduction in the size of the outward appearance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel used in video cameras and the like.

0002

2. Description of the Related Art A zoom lens consists of a focus section, a zoom section, and a master section.
The zoom section has a zoom mechanism that performs a zoom operation. For this reason, the structure of zoom lens barrels has been complicated and has tended to become larger and heavier. On the other hand, today
As video cameras become smaller and lighter, zoom lenses used in them are also desired to be smaller and lighter. In line with this trend, efforts are being made to simplify the structure of zoom lens barrels to make them smaller, lighter, and lower in cost.

First, the structure of the zoom portion of a conventional zoom lens barrel will be explained.

FIG. 9 is a sectional view showing a main part of the zoom portion structure of a conventional zoom lens barrel. The zoom section includes a variator lens group 101 and a compensator lens 102.
, a variator frame 103 and a compensator frame 104 that hold these, a guide rod 105 that guides these variator frames 103 and compensator frames 104 so as to move in the optical axis direction, and these variator frames 103 and 104, respectively. ta frame 1
03, a cam follower 106 attached to the compensator frame 104, a cam ring 107 having a cam groove that slides into the outer diameter of each of these cam followers 106, a fixed cylinder 108 that rotatably holds this cam ring 107, A zoom ring 110 has an engaging portion 109 that engages with the cam ring 107 and rotates the cam ring 107, and a gear that meshes with a gear provided on the outer periphery of the zoom ring 110 to drive the zoom ring 110. Drive gear 11
1 is attached to a rotating shaft, and a cam ring 107 is made up of a lug cylinder 113 that prevents the cam ring 107 from protruding from the fixed cylinder 108.

In this configuration, when the zoom ring is rotated by the zoom motor, the cam ring also rotates together with the zoom ring. This cam ring has two spiral cam grooves, each of which has a cam follower fitted into it.
As the cam ring rotates, the cam follower is guided by this cam groove and moves. These cam followers are attached to the variator frame holding the variator lens group and the compensator frame holding the compensator lens, so as the cam follower moves, the variator lens group and compensator lens move to the guide rod. It moves in the direction of the optical axis while being guided. By operating as described above, zooming operation becomes possible.

[0006]

SUMMARY OF THE INVENTION The structure of the zoom portion of the zoom lens barrel described above has the following problems from the viewpoint of miniaturization and weight reduction. Since the cam ring is located outside the variator frame and compensator frame, the outer diameter of the zoom lens barrel is increased. Furthermore, since the zoom ring for rotating this cam ring is also located outside the fixed barrel, the outer diameter of the zoom lens barrel is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens barrel that can solve the problems of the prior art described above and can be made smaller and lighter.

[0008]

[Means for Solving the Problems] In order to achieve this object, the present invention includes means for moving a variator frame, and controlling movement of a compensator frame by means for moving the variator frame. We have provided means. That is, the variator frame is moved in the optical axis direction by a feed screw and a rack without using a cam ring or a cam follower. A compensator frame control member was provided for moving the compensator frame in the optical axis direction using a gear attached to the feed screw.

[0009]

[Function] The cam ring for moving the variator lens group in the direction of the optical axis for effecting the variable magnification effect has been removed, and instead it is moved by a feed screw and a rack. Since the compensator lens is moved in the optical axis direction by a gear attached to the feed screw, the outer diameter of the zoom lens barrel can be made smaller, which has the effect of making the zoom lens more compact. Also, since the outer diameter of the zoom lens barrel is smaller, it has the effect of reducing weight.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a view showing an embodiment of a zoom lens barrel according to the present invention, and FIG. 2 is a partial sectional view of a main part showing a zoom portion. First, let's talk about the configuration. 1 is a focus lens group for focusing on the subject, 2 is a front lens holder that holds the focus lens group, 3 is a focus ring that has a helicoid thread and holds the front lens holder, and 4 is a variator. −
6 is a compensator frame that holds the compensator lens group 5; 8 is a guide rod that guides the variator frame to move the compensator frame in the optical axis direction; 9 is a compensator frame that holds the compensator lens group 5; 1 is a pressing spring that presses the compensator frame; 10 is a pressing pin provided on the compensator frame;
1 is a feed screw 16 that moves the variator frame in the optical axis direction.
12 is an intermediate gear that meshes gear 11 and drive gear 13; 14 is a zoom motor with drive gear 13 attached to the output shaft; 15 is a helicoid that meshes with the helicoid thread of the focus ring. Variable with threaded part
17 is a gear 1
1, a control member having a gear portion that meshes with 1 and whose surface that contacts the pressing pin is a cam surface and is rotatably held with respect to the fixed cylinder 15; 19, an overlay cylinder holding a fixed compensator lens 18; is the iris mode that operates the aperture 21.
22 is an inner master cylinder that holds the master lens groups 23a and 23b, 24 is an outer master cylinder that holds the inner master cylinder 22, 25 is a leaf spring for removing play in the optical axis direction of the feed screw 16, 26 is a holding plate that supports the guide rod 8 and the feed screw 16.

Next, the operation will be described. When the rotation shaft of the zoom motor rotates, a drive gear 13 integrally attached thereto rotates. Since the drive gear 13 meshes with the gear 11 via the intermediate gear 12, the rotation of the drive gear is transmitted and the gear 11 also rotates. At this time, the gear 11 is the feed screw 1
Since it is attached integrally with the feed screw 6, it rotates together with the feed screw 16. This feed screw 16 is connected by a screw to a rack portion provided on a variator frame holding a group of variator lenses for performing a magnification change action. Therefore, the variator frame is moved in the optical axis direction by rotation of the feed screw. Furthermore, since the gear 11 meshes with the gear portion of the control member 17, rotation is also transmitted to the control member 17. Therefore, when the control member 17 rotates, the cam surface provided on the control member 17 also rotates. At this time, on the cam surface of the control member 17,
Since the press pin provided on the compensator frame holding the compensator lens is pressed, when the cam surface rotates, the press pin moves as the position of the cam surface changes in the optical axis direction. The shape of this cam surface is such that the compensator lens position corresponds to the movement position of the variator lens group. That is, as described above, the zooming operation is achieved by rotating the gear 11 due to the rotation of the zoom motor.

Next, another embodiment of the control member will be explained with reference to FIG.

Reference numeral 27 denotes a compensator frame with the cam surface of the control member 17 integrally provided on the end surface, 28 a rotating body having an abutment pin 29 that comes into contact with this cam surface, and this rotating body 28
has a gear part that meshes with the gear 11. Moreover, this rotating body 28 is rotatably held relative to the fixed cylinder 15. This cam surface and the contact pin 29 are pressed by the pressing spring 9.

In this configuration, the gear 11 operates as a zoom mode.
When rotated by the motor, the rotating body 28 rotates. At this time, the contact pin 29 also rotates, and the position where it contacts the cam surface provided on the compensator frame changes. Therefore, the compensator frame moves in the optical axis direction in response to changes in the shape of the cam surface. The variator frame is similarly moved in the optical axis direction by rotation of the feed screw 16 to which the gear 11 is attached as described above. Therefore, the variable magnification operation is achieved in the same manner as described above.

An embodiment of a variator frame structure for moving the variator frame in the optical axis direction by the feed screw 16 will be described with reference to FIG.

30 is a rack section provided in the variator frame 4;
Reference numeral 31 denotes an elastic deformation section in which the rack section is elastically deformed. The rack section 30 is elastically deformed by the elastic deformation section 31 and screwed together with the feed screw 16. For this reason, the feed screw 16
The rack portion 30 and the rack portion 30 are connected without play, and the feed caused by the rotation of the feed screw 16 is correctly transmitted. Therefore, as the feed screw rotates, the variator frame is guided by the aforementioned guide rod and moves in the optical axis direction. In this embodiment, the rack portion is integrated with the variator frame, but the rack portion may be separated and attached to the variator frame via an elastic member.

Next, an example of a method for performing initial settings will be explained using FIG. 5.

The initial setting method is to adjust the position of the compensator lens with reference to the position of the variator lens group. First, let's talk about the configuration. 32 is a stopper provided on the fixed barrel 15 to set the initial position of the variator lens group; 33 is an initial position setting member that rotates with respect to the gear 34; and 35 is a stopper portion that fixes the initial position setting member to the feed screw 16. A set screw 36 is a screw that fits into a V groove provided in the gear 34, and 37 is a set screw 35 and a screw 3.
6 is an operation hole provided in the fixed tube so that it can be operated from outside the fixed tube.

Next, the operation will be explained. First, the variator frame holding the variator lens group is fed by the feed screw 16 until it comes into contact with the stopper part 32. At this time, the stopper position is set so that the variator lens group is at the initial position. Next, loosen the screw 36 and remove the gear 34.
Rotate. Since this gear 34 is not press-fitted into the feed screw 16, only the gear 34 rotates without rotating the feed screw 16. At this time, since the gear 34 meshes with the rotating body 28 shown in the above embodiment, the rotation of the gear 34 is transmitted to the rotating body 28. Therefore, the contact position between the pin 29 provided on the rotating body 28 and the cam surface provided on the compensator frame 27 changes. This allows the compensator frame to move independently in the optical axis direction. After moving to the initial position, the screw 36 may be tightened. The initial position is confirmed by observing a spot image through a zoom lens system. The initial position setting member 33 functions to set the rotational position of the gear 34 and to hold the screw 36.

Next, another embodiment in which the pin 29 is pressed against the cam surface of the compensator frame 27 will be described with reference to FIG.

Reference numeral 38 indicates a spring attachment pin attached to the compensator frame 27, 39 indicates a spring hook portion provided on the fixed tube 15, and 40 indicates a portion between the spring attachment pin 38 and the spring hook portion 39 provided on the fixed tube 15. The tension spring 41 is attached to the fixed tube 1 to attach this tension spring.
This is the slot provided in 5.

Due to the tensile force of the tension spring 40, a tensile force acts between the compensator frame 27 and the fixed cylinder 15. Therefore, the pin 29 is pressed against the cam surface of the compensator frame 27.

Next, an example of detecting the zoom position is shown in FIG.
Explain using.

42 is a brush attached to the variator frame;
Reference numeral 43 denotes a resistor fitted into the fixed tube 15, and 44 a terminal for taking out the resistance value of the resistor.

A brush 42 attached to the variator frame,
It is kept in contact with the resistor 43. When the variator frame 4 is moved in the optical axis direction by the feed screw 16, the contact position of this brush with the resistor 43 changes. Along with this, the resistance value at the terminal from which the resistance value is taken out changes. Therefore, the position of the variator lens group can be detected based on the resistance value. Also, this resistor 4
The stopper can be removed by positioning the variator frame 3 with respect to the fixed cylinder 15 and setting the stopping position of the variator frame in the optical axis direction using the resistance value of the resistor.

Next, another embodiment for setting the stop position of the variator frame in the optical axis direction will be described with reference to FIG.

Reference numeral 45 denotes a light emitting section that emits light, 46 a light receiving section that receives light, and 47 a light shielding plate provided on the variator frame.

The light emitted from the light emitting section 45 is made to enter the light receiving section 46. The light shielding plate blocks light when it comes between the light emitting part and the light receiving part. To stop the movement of a variator frame when light is blocked. In this way, it has the same effect as a stopper.

[0029]

Effects of the Invention As described above, by providing a means for moving the variator frame and a means for controlling the movement of the compensator frame by means of moving the variator frame, the cam that was previously required can be removed. Rings and cam followers become unnecessary. Therefore, the space required to hold the cam ring is no longer required, and the outer size of the zoom lens barrel can be made smaller. Therefore, the size of the zoom lens barrel can be reduced. Furthermore, the weight can be reduced due to the smaller external size.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the zoom lens barrel of the present invention.

FIG. 2 is a partial cross-sectional view of the main part showing the zoom part of the present invention;

FIG. 3 is a diagram showing another example of the control member;

FIG. 4 is a diagram showing a variator frame structure according to the present invention;

FIG. 5 is a diagram showing an example of an initial setting method;

FIG. 6 is a diagram showing another embodiment in which a pin is pressed against a cam surface;

FIG. 7 is a diagram showing an embodiment showing means for detecting a zoom position;

FIG. 8 is a diagram showing another embodiment for setting the stopper position of the variator frame,

FIG. 9 is a diagram showing a conventional example showing the configuration of a zoom section.

[Explanation of symbols]

4...variator frame, 5...variator lens group, 6...Compensator frame, 7...Compensator lens, 8...Guide rod, 9...pressing spring, 10...pressing pin, 11, 34...gear, 12... intermediate gear, 13... Drive gear, 14...zoom motor, 16...Feed screw, 17...control member, 19... Jumpsuit tube, 28...Rotating body, 29...Abutment pin, 30...Rack section, 31...Elastic deformation part, 32...stopper part, 33...Initial position setting member, 36...screw, 37...operation hole, 38...Spring mounting pin, 39...Spring hook part, 40... tension spring, 41... Groove, 42...Brush, 43...Resistor, 44...terminal, 45... Light emitting part, 46...light receiving section, 47... Light shielding plate.

Claims (1)

[Scope of Claims] [Claim 1] A variator frame that holds a variator lens group that performs a magnification change function and is movable in the optical axis direction along a guide rod; A compensator frame that holds a compensator lens for correcting aberrations, etc. and is movable in the optical axis direction along a guide rod is moved by a means for moving in the optical axis direction to perform a zoom operation. In a lens barrel having a zoom section,
A zoom lens barrel characterized by comprising: means for moving the variator frame; and means for controlling the movement of the compensator frame by the means for moving the variator frame.
2. Means for controlling movement of the compensator frame,
a position control unit such as a cam surface provided on the compensator frame;
2. The zoom lens according to claim 1, further comprising an engaging member having an abutting portion that engages with the means for moving the variator frame and abuts on a position control portion such as the cam surface. lens barrel. 3. The apparatus according to claim 2, further comprising a changing means for changing the position of the abutting part such as a cam surface that abuts the position control part with respect to the engaging member. Zoom lens barrel. 4. A variator frame that holds a variator lens group that performs a magnification change function and is movable in the optical axis direction along a guide rod, and a compensator that corrects aberrations, etc. that occur due to movement of the variator lens group. - has a zoom section which performs a zoom operation by moving a compensator frame that holds the lens and is movable in the optical axis direction along the guide rod by means of moving the compensator frame in the optical axis direction; In the lens barrel,
A means for moving the variator frame, a means for controlling the movement of the compensator frame by the means for moving the variator frame, and a detection means for detecting the moving position of the variator frame are provided. Features a zoom lens barrel. 5. Detecting means for detecting the moving position of the variator frame comprises a resistor provided on a fixed lens barrel containing a zoom section, and a resistor provided on the variator frame so as to come into contact with the resistor. 5. The zoom lens barrel according to claim 4, further comprising a contactor.