JPH0961695A - Lens driving device - Google Patents

Abstract

PURPOSE: To reduce cost by simplifying the zooming mechanism and the AF mechanism of a camera. CONSTITUTION: A 1st lens group and a 2nd lens group are housed in a zoom ring 21 and provided to freely move in the direction of an axial line Y. Cam grooves 30 and 31 engaged with the pins 28 and 29 fixed in the respective lens groups are formed on the zoom ring 21. The cam groove 30 is formed like stairs corresponding to a zooming position, and the cam groove 31 is formed like stairs further for every zooming position. By driving a motor 25, the zoom ring 21 is turned and the 1st and the 2nd lens groups perform zooming operation. By finely rotating the motor 25 at each zooming position, the 1st lens group is moved in its optical axis direction in a state where the 2nd lens group is still stopped. Thus, zooming and AF operation are performed only by driving the normal and reverse rotation of the motor 25.

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 a camera, and more particularly to a lens driving device having a zooming function and an autofocus function.

[0002]

2. Description of the Related Art Conventionally, as a lens driving device provided in a still video camera or the like, there is known a lens driving device provided with an auto zooming mechanism capable of automatically changing an angle of view of a lens by an actuator. FIG. 6 shows a schematic configuration of a zooming mechanism of such a lens driving device. The zooming mechanism shown in this figure includes a rotatable zoom ring 21 and a zoom gear 2 at the rear end thereof.
3 is provided, and this zoom gear is connected to the output shaft of a motor 25 dedicated to the zoom mechanism via a reduction gear train 24. Inside the zoom ring 21, for example, a first lens group L1 and a second lens group L2 as shown in FIG. 7A are housed, and a pin 28 fixed to these lens groups L1 and L2. , 29 are cam grooves 3 formed in the zoom ring.
0 and 31 are engaged. These pins 28 and 29 can be displaced only in the axis Y direction of the zoom ring 21, and when the zoom ring 21 is rotated by the motor 25, the lens groups L1 and L2 are guided to the cam grooves 30 and 31, respectively. 7
The zooming operation is performed by displacing as shown by the arrow in (b).

[0003]

The focus adjustment of the subject is
For example, it is performed by slightly moving the front lens group while fixing the position of the rear lens group. For this reason, for example, inside the zoom ring 21, the second lens unit L2 is independently driven to automatically adjust the focus of the subject.
F) is provided with a mechanism, and a configuration is known in which the AF mechanism is driven by using a motor dedicated to AF (not shown) as a drive source. However, in such a configuration, in addition to the zooming motor 25, a motor dedicated to AF must be provided, which causes a problem that the entire camera mechanism becomes complicated and the cost becomes high.

The present invention is intended to solve such problems, and an object of the present invention is to provide a lens driving device which enables zooming operation and AF operation with a simple and compact structure.

[0005]

A lens driving device according to the present invention includes first and second lens groups, a means for guiding the movement of these lens groups in the optical axis direction, and a guide means for the movement. A single drive means for moving the first and second lens groups, the drive means moves the first and second lens groups during the zooming operation, and the drive means moves the first and second lens groups during the zooming operation. Second with the lens group stopped
It is characterized by moving the lens group of.

[0006]

The present invention will be described below with reference to illustrated embodiments. FIG. 1 is an external view of a still video camera to which an embodiment of the present invention is applied.

A photographing lens 11, a finder window 12 and a sensor window 13 are provided on the front surface of the body 10 of the still video camera, and a photometric and distance measuring device (not shown) is housed behind the sensor window 13. A zooming lever 14 is provided on the upper surface of the main body 10. By operating the zooming lever 14, a zooming operation is performed.
Is adjusted to the tele side or the wide side. A release button 15 is provided on the top surface of the main unit. When this button is pressed halfway, color measurement and distance measurement operations are performed, and when it is fully pressed,
An automatic focus adjustment (AF) operation is performed. That is, the state of the switch that is turned on / off in synchronization with the operation of the zooming lever 14 and the release button 15 is the control circuit (E
It is input to the CU) 27, and the zooming operation and the AF operation are performed under the control of the ECU 27.

FIG. 2 shows the zoom ring 21 housed inside the main body 10 and its drive mechanism. A zoom gear 23 having a diameter larger than that of the zoom ring 21 is provided at the rear end portion of the zoom ring 21.
4 is connected to the output shaft 26 of the zoom motor 25. The zoom motor 25 is driven by an output signal from the ECU 27, and by operating the zooming lever 14 (FIG. 1) connected to the ECU 27, the zoom motor 25 is rotated, and the zoom ring 21 has its axis Y. Rotate around.

A plurality of lens groups constituting the taking lens 11, for example, first and second lens groups are housed in the zoom ring 21, and pins 28 and 29 fixed to these lens groups are zoom rings. Cam grooves 30, 3 formed in 21
1 is engaged. The cam grooves 30 and 31 are the zoom ring 21.
The pins 28 and 29 are formed so as to cross the upper part in an oblique direction, and the pins 28 and 29 can be displaced only in the direction of the axis Y of the zoom ring 21 by a guide mechanism (not shown). Therefore, when the zoom ring 21 rotates, the pins 28 and 29 of each lens group are guided by the cam grooves 30 and 31 and displaced in the optical axis direction (corresponding to the axis Y), and the zooming operation is performed. The cam groove 30,
Reference numeral 31 is formed in a stepwise shape so that each lens group can take a plurality of zooming positions.

In order to set the lens group at a desired zooming position, the zoom motor 25 is composed of a motor capable of rotating in the forward and reverse directions, and a code plate 32 for detecting the current zooming position is attached to the zoom ring 21. There is. A conductive pattern is formed on the code plate 32 so that a preset number of zooming positions can be respectively recognized. In this embodiment, the camera is configured to occupy eight zooming positions. Therefore, in order to cope with the number of the zooming positions, the conductive pattern has a total of 3 patterns.
Row pattern rows are formed.

A zooming position detection brush 33 provided on the camera body side is in sliding contact with the conductive pattern on the code plate 32. Current zooming position information obtained by contact (or non-contact) between the brush 33 and the conductive pattern on the code plate 32 is input to the ECU 27, and the ECU 27 rotates or stops the zooming motor 25 based on this information. Let

The rotation of the zoom motor 25 is controlled by the zoom gear 23.
The reduction gear train 24 that transmits to is provided with an encoder 34 with a slit that meshes with one of the gears, and a photo interrupter 35 that projects a light beam to the encoder 34 and receives the light through the slit. . Encoder 34 and photo interrupter 35
Is for positioning the lens group L2 at the reference position set within each zooming position when the second lens group after zooming is operated by the autofocus (AF) operation.

A code disk 36 for detecting the current focus position of the lens is meshed with the reduction gear train 24. The number of teeth of the code disk 36 is 1 for each lens group.
It is set so as to be able to make one rotation while it is in one of the zooming positions, and a conductive pattern is attached to the surface of the code disk 36 so that the set number of focus positions can be respectively recognized. The camera of this embodiment is
It is set so as to be able to occupy three focus positions per one zooming position, and as the conductive pattern, in order to cope with the number of focus positions, there are two inner and outer pattern rows composed of combinations with and without patterns. Has been formed.

A focus position detecting brush 37 provided on the camera body side is provided on the conductive pattern on the code disk 36.
Are in sliding contact with each other. The current focus position information obtained by contact (or non-contact) between the brush 37 and the conductive pattern on the code disk 36 is input to the ECU 27, and the ECU 27 drives the zooming motor 25 based on this information, or Stop.

The zooming mechanism and the AF mechanism in this embodiment will be described. FIG. 3 shows a correspondence relationship between the first lens group cam groove 30 and the second lens group cam groove 31 provided in the zoom ring 21, the conductive pattern on the code plate 32, and the light receiving timing of the photo interrupter 35. FIG. 4 is a partially enlarged view showing the correspondence with the conductive pattern on the code disk 36.

The camera of this embodiment has eight stages of zooming positions a to h from the wide side (W) to the tele side (T).
And each cam groove 30 and 3 so that a focus position can be set at three stages, one far, one middle, and one near each zooming position.
1 is formed stepwise. That is, the cam groove 30 that determines the position of the first lens group corresponds to the zooming number as shown in FIG. 3, and has eight flat portions 30a to 30 in total.
Conductive patterns having a total of three rows A, B, and C, which are formed in a staircase shape having h, are arranged in different pattern combinations corresponding to the respective zooming positions. On the other hand, the cam groove 31 that determines the position of the second lens group is generally formed in a staircase shape in accordance with each of the zooming positions a to h, but is further divided into one zooming position. As shown in FIG. 4, each zooming section has a total of three flat portions 31k, 31m and 31n. Corresponding to the flat portions 31k, 31m and 31n, the conductive patterns are composed of two rows C and D, and are arranged in different pattern combinations. The light reception timing of the photo interrupter 35 corresponds to a long-distance focus position k among the three focus positions k, m, and n, as indicated by a symbol P.

The operations of the zooming mechanism and the AF mechanism described above will be described with reference to the timing chart of FIG.

When the power of the camera is turned on, the EC
A drive signal is output from U27 to the zooming motor 25, and each lens group in the zoom ring 21 returns to the initial position (for example, the zooming position a corresponding to the wide side). This drive signal is used for the zooming position detection brush 33.
Is output until a signal (for example, 1.1.1) corresponding to the conductive pattern at the zooming position a is detected (see FIG. 3).

After that, when the zooming lever 14 is pushed to the tele side, the zooming motor 25 is driven to rotate the zoom ring 21, and the pins 28 and 29 of each lens group are moved toward the zooming position h (tele position). Moving. On the contrary,
When the zooming lever 14 is pushed to the wide side, the zooming motor 25 rotates in the reverse direction, whereby each lens group moves toward the zooming position a (wide position). The movement of each of these lens groups is stopped when the zooming lever 14 is released. In this stopping operation, the zoom ring 21 keeps the zooming motor 25 until the photo interrupter 35 detects the slit light from the encoder 34.
Micro rotation by.

After the desired zooming position is obtained in this way, when the release button 15 is half pressed, the distance measuring sensor (not shown) measures the distance to the object, and E
The focus position is determined by the CU 27. When the release button 15 is fully pressed, the zoom motor 25
Rotates, and the zoom ring 21 slightly rotates to the focus positions k, m, and n corresponding to the distance measurement result within the same zooming position. The motor drive signal at this time is a signal corresponding to the conductive pattern of the focus position detection brush 37 at the predetermined focus position (for example, in the case of the focus position m,
0 (see FIG. 4)) is output. Then, exposure control is performed at this focus position. In this way, automatic focus adjustment of the subject is performed,
After the exposure control ends, the captured image data is recorded on the recording medium.

After the shooting is completed, in order to prepare for the next shooting, the zooming motor 25 reversely rotates until the photo interrupter 35 detects the slit light from the encoder 34, and the pins 28 and 29 move to the focus position k. This completes one shooting operation.

As described above, according to the present embodiment, the cam grooves 30 and 31 for moving the lens in accordance with the zooming operation are formed in a step shape, and the cam groove 30 of the rear group lens is formed in a step shape corresponding to each zooming position. Since the cam grooves 31 of the front lens group are further formed stepwise at each zooming position, the front lens group can be moved stepwise without moving the rear lens group, and the single zooming motor 25 can be used. , The AF operation of the camera can also be used.

Although the above-described embodiment applies the zoom device of the camera to the zoom mechanism of the still video camera, the present invention can also be applied to a camera using a silver salt film.

[0024]

As described above, according to the present invention, zooming and focusing operations can be performed by one motor, and therefore the camera mechanism can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is an external view of a still video camera according to an embodiment of the present invention.

FIG. 2 is an external perspective view of a zooming mechanism of the still video camera of FIG.

3 is a development view of a cam groove and a conductive pattern of FIG.

FIG. 4 is a partially enlarged view of the cam groove and the code disc of FIG.

FIG. 5 is a shooting timing chart of a still video camera.

FIG. 6 is an external perspective view of a zooming mechanism of a conventional still video camera.

7 is a diagram showing a lens group housed in the zoom ring of FIG. 6 and a positional relationship during zooming.

[Explanation of symbols]

 10 Still Video Camera Main Body 11 Shooting Lens 21 Zoom Ring 25 Zoom Motor 27 Control Circuit (ECU) 28, 29 Pins 30, 31 Cam Groove

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[Procedure amendment]

[Submission date] December 28, 1994

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 3

[Correction method] Change

[Correction contents]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Conventionally, as a lens driving device provided in a still video camera or the like, there is known a lens driving device provided with an auto zooming mechanism capable of automatically changing an angle of view of a lens by an actuator. FIG. 6 shows a schematic configuration of a zooming mechanism of such a lens driving device. The zooming mechanism shown in this figure includes a rotatable zoom ring 21 and a zoom gear 2 at the rear end thereof.
3 is provided, and this zoom gear is connected to the output shaft of a motor 25 dedicated to the zoom mechanism via a reduction gear train 24. Inside the zoom ring 21, for example, a first lens group L1 and a second lens group L2 as shown in FIG. 7A are housed, and a pin 29 fixed to these lens groups L1 and L2. , 28 are cam grooves 3 formed in the zoom ring.
1 and 30 are engaged. These pins 29 and 28 can be displaced only in the direction of the axis Y of the zoom ring 21, and when the zoom ring 21 is rotated by the motor 25, the lens groups L1 and L2 are guided to the cam grooves 31 and 30 , respectively. 7
The zooming operation is performed by displacing as shown by the arrow in (b).

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction contents]

[0003]

The focus adjustment of the subject is
For example, it is performed by slightly moving the front lens group while fixing the position of the rear lens group. For this reason, for example, inside the zoom ring 21, the first lens unit L1 is independently driven to automatically adjust the focus of the subject.
F) is provided with a mechanism, and a configuration is known in which the AF mechanism is driven by using a motor dedicated to AF (not shown) as a drive source. However, in such a configuration, in addition to the zooming motor 25, a motor dedicated to AF must be provided, which causes a problem that the entire camera mechanism becomes complicated and the cost becomes high.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

A lens driving device according to the present invention includes first and second lens groups, a means for guiding the movement of these lens groups in the optical axis direction, and a guide means for the movement. and a single drive means for moving the first and second lens groups during zooming operation, the drive means moves the first and second lens groups, during the autofocus operation, the drive means of the second First with the lens group stopped
It is characterized by moving the lens group of.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

The zoom ring 21 accommodates a plurality of lens groups constituting the taking lens 11, for example, first and second lens groups, and pins fixed to these lens groups.
29 and 28 are cam grooves 31 and 3 formed in the zoom ring 21.
0 is engaged. The cam grooves 31 and 30 are provided on the zoom ring 21.
It is formed diagonally across the top,
29 and 28 can be displaced only in the direction of the axis Y of the zoom ring 21 by a guide mechanism (not shown). Therefore, by the rotation of the zoom ring 21, the pins 29 and 28 of each lens group are guided by the cam grooves 31 and 30 and displaced in the optical axis direction (corresponding to the axis Y), and the zooming operation is performed. The cam groove 31,
Reference numeral 30 is formed in a stepped shape so that each lens group can take a plurality of zooming positions.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

The rotation of the zoom motor 25 is controlled by the zoom gear 23.
The reduction gear train 24 that transmits to is provided with an encoder 34 with a slit that meshes with one of the gears, and a photo interrupter 35 that projects a light beam to the encoder 34 and receives the light through the slit. . Encoder 34 and photo interrupter 35
Is for positioning the lens unit L1 at the reference position set within each zooming position when the first lens unit after zooming is operated by the auto focus (AF) operation.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

The zooming mechanism and the AF mechanism in this embodiment will be described. FIG. 3 shows a correspondence relationship between the first lens group cam groove 31 and the second lens group cam groove 30 provided in the zoom ring 21, the conductive pattern on the code plate 32, and the light receiving timing of the photo interrupter 35. FIG. 4 is a partially enlarged view showing the correspondence with the conductive pattern on the code disk 36.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The camera of this embodiment has eight stages of zooming positions a to h from the wide side (W) to the tele side (T).
And each cam groove 31 , 3 so that a focus position can be taken in three stages, one for far / middle / near for each zooming position.
Both 0s are formed stepwise. That is, the cam groove 30 that determines the position of the second lens group corresponds to the zooming number, as shown in FIG. 3, and has eight flat portions 30a to 30 in total.
Conductive patterns having a total of three rows A, B, and C, which are formed in a staircase shape having h, are arranged in different pattern combinations corresponding to the respective zooming positions. On the other hand, the cam groove 31 that determines the position of the first lens group is generally formed in a staircase shape in accordance with each of the zooming positions a to h, but it is further divided into a plurality of zooming positions. As shown in FIG. 4, each zooming section has a total of three flat portions 31k, 31m and 31n. Corresponding to the flat portions 31k, 31m and 31n, the conductive patterns are composed of two rows C and D, and are arranged in different pattern combinations. The light reception timing of the photo interrupter 35 corresponds to a long-distance focus position k among the three focus positions k, m, and n, as indicated by a symbol P.

[Procedure amendment 10]

[Document name to be amended] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction contents]

FIG. 7

Claims (3)

[Claims] 1. A first lens group and a second lens group, a means for guiding the movement of these lens groups in the optical axis direction, and a single unit for moving the first and second lens groups via the guiding means. One driving unit, the driving unit moves the first and second lens groups during a zooming operation, and the driving unit moves the first lens group with the first lens group stopped during the autofocusing operation. A lens driving device characterized by moving the second lens group. 2. The guide means includes a cylindrical zoom cam that houses each lens group so as to be movable in the optical axis direction, and the zoom cam has a plurality of cams with which pins provided in each lens group engage. The lens driving device according to claim 1, wherein a groove is formed. 3. The cam groove is formed stepwise so that the first and second lens groups stop at any of a plurality of zooming positions, and the cam groove corresponding to the second lens group further comprises: The lens driving device according to claim 1, wherein the lens driving device is formed stepwise at each zooming position.