JPH07174955A - Lens driving device - Google Patents

Abstract

PURPOSE:To provide a lens driving device capable of easily escaping from a lens-bitten state even in the case of causing the bite of a lens, with respect to a lens driving device using a stepping motor. CONSTITUTION:The device is provided with the stepping motor 7 for driving the lens, a driving means 8 for supplying a driving pulse to the stepping motor, velocity controlling means 9 and 16 for controlling the driving means and reducing the cycle of the driving pulse for a fixed period at the start of driving. And also, the device is provided with the stepping motor 7 for driving the lens, a driving means 8 for supplying the driving pulse to the stepping motor 7 and torque controlling means 9 and 17 for controlling the driving means 8 and increasing the strength of the driving pulse for a fixed period at the start of driving.

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 using a stepping motor as a means for driving a lens.

[0002]

2. Description of the Related Art A focusing lens in an inner focus type lens unit used in a video camera or the like is small and lightweight and requires accurate positioning. Therefore, a stepping motor has been conventionally used for driving. There is.

FIG. 3A shows a main part of a lens driving device using a stepping motor. The focusing lens 31 is supported by a support member 32, and the support member 32 is engaged with a worm gear 34 formed on the rotation shaft of a stepping motor 33. Therefore, when the stepping motor 34 rotates, the focusing lens 31 moves in the optical axis direction. Then, in order to improve responsiveness, the stepping motor 33 is driven at high speed. Also,
The movable range of the lens is mechanically predetermined.

The inner focus type lens unit having a zoom correction lens is composed of a front lens 41, a zoom lens 42, a zoom correction lens 43, and a focus lens 44, as shown in FIG. 4A. The zoom lens 42 moves from the wide (W) side to the tele (T) side and from the T side to the W side. Only when moving from the T side to the W side, the zoom correction lens 43 moves to the W side when the zoom lens 42 reaches a certain W side. Further, the focusing lens 44 moves from the near point side to the infinite side and from the infinite side to the near point side by driving a stepping motor (not shown).

[0005]

However, when the lens is out of the movable range due to the runaway of the stepping motor or the like, as shown in FIG. 3B, the worm gear 34 is used.
And the support member 32 bite (hereinafter referred to as "lens biting").
Will be generated). In this lens engagement state, the engagement portion of the support member 32 with the worm gear 34 is deformed, and the frictional force between the worm gear 34 and the support member 32 increases. Therefore, since the stepping motor driven at a high speed has a small torque, it may not be possible to escape from the state where the lens is caught, which may hinder the driving of the lens.

The inner focus type lens unit shown in FIG. 4 has a complicated structure, and both the near point end 45 and the infinite end 46 of the focusing lens 44 are set inside the movable range of the focusing lens 44. Yes,
I try not to go outside the end points. However, the focusing lens 44 may go outside the end point due to runaway. At this time, when the zoom lens 42 is at the W end and the focus lens 44 is outside the near point end, as shown in FIG. 4B, the zoom correction lens 43
And the focusing lens 44 come into contact with each other, which may cause a lens biting state.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lens driving device using a stepping motor, which can easily get out of the state even if the lens is caught.

[0008]

In order to solve the above problems, the present invention provides, as a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, and the driving means. And a cycle control means for reducing the cycle of the drive pulse for a predetermined period at the start of driving.

As a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, a power supply device for supplying power to the driving means, and a start-up operation of the power supply device. Initial control means for controlling the drive circuit to reduce the cycle of the drive pulse for a predetermined period to drive the stepping motor.

Further, as a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, and the driving means are controlled, and the magnitude of the driving pulse is controlled for a predetermined period at the start of driving. And a torque control means for increasing the torque.

Further, as a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, a power supply device for supplying power to the driving means, and a start-up operation of the power supply device. Initial control means for controlling the drive circuit and increasing the magnitude of the drive pulse for a predetermined period to drive the stepping motor.

[0012]

When the drive is started, the cycle of the drive pulse to the stepping motor is reduced for a predetermined period, and the drive torque is increased during that period. In the stepping motor, if the driving pulses have the same magnitude, the driving torque increases as the cycle of the driving pulses decreases.

Further, when the power is turned on, the stepping motor is driven in a state where the cycle of the drive pulse to the stepping motor is reduced for a predetermined period.

At the start of driving, the magnitude of the driving pulse to the stepping motor increases for a predetermined period, and the driving torque increases during that period.

When the power is turned on, the stepping motor is driven in a state where the magnitude of the driving pulse to the stepping motor is increased for a predetermined period.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of a video camera including a lens driving device according to the first and second embodiments of the present invention. In the figure, reference numeral 1 denotes an inner focus type lens unit, which has a front lens 1a, a zoom lens 1b, a zoom correction lens 1c, and a focusing lens 1d. Then, the light from the subject passes through the lens unit 1 and the diaphragm mechanism 2 that adjusts the amount of light, and reaches the image sensor 3 that converts the light into an electric signal. The output of the image sensor 3 is input to the video signal processing circuit 4 and becomes a video signal.

On the other hand, 5 is a zoom motor for driving the zoom lens 1b, which is driven by the zoom motor drive circuit 6 to change the focal length of the lens unit 1. Also,
Reference numeral 7 denotes a stepping motor that drives a focusing lens, which is driven by a stepping motor drive circuit 8 and is controlled so that the light passing through the lens unit 1 is focused on the image pickup surface of the image pickup element 3. The zoom motor drive circuit 6 and the stepping motor drive circuit 8 are controlled by the microcomputer 9. Reference numeral 10 is a zoom switch for operating the zoom lens 1b, 11 is a zoom encoder for transmitting the position of the zoom lens 1b to the microcomputer 9, and 12 is position information of the focusing lens 1d. A counter that counts drive pulses supplied to the stepping motor 7, and 13 integrates a high frequency component of the luminance signal from the video signal processing circuit 4 for each field, and uses a microcomputer as a focus evaluation value used for so-called hill-climbing autofocus control. 9, an integrating circuit for inputting to 9, a power supply device for supplying power to each part of the video camera, 15 for a power switch, 16 for a cycle switch for switching the cycle of the current supplied by the stepping motor drive circuit 8 to the stepping motor 7. is there.

Next, the operation of the first embodiment will be described. The focus position changes when the distance between the subject and the video camera changes. Therefore, the microcomputer 9 controls the stepping motor drive circuit 8 so that the focus evaluation value, which is the integrated value of the high frequency components of the video signal supplied by the integration circuit 13, becomes maximum, and drives the stepping motor 7 to focus. Move the lens to climb the mountain and perform auto focus. Since the lens unit 1 is of the inner focus type, the focus position changes when the zoom lens 1b moves. Therefore, the microcomputer 9 detects the position of the zoom lens 1b by the zoom encoder 11, and according to the detection result, the stepping motor drive circuit 8
Is controlled to drive the stepping motor 7 to move the focusing lens 1b.

In any case, the microcomputer 9 controls the cycle changeover switch 15 every time the position change of the focusing lens 1d is started, and the stepping motor drive circuit 8 supplies it to the stepping motor 7. The cycle of the drive current is reduced for a predetermined period. Therefore,
During that time, the driving torque of the stepping motor 7 increases, so that even if a lens biting state occurs, it is possible to easily get out of this state.

Next, the operation of the second embodiment will be described. Although the functional block diagram is the same as that of the first embodiment, the cycle changeover switch 16 is controlled every time the power supply device 14 is activated and power supply is started. That is, since the driving torque of the stepping motor 7 increases each time the power is supplied, even if the lens jamming state occurs, it is possible to easily get out of the state. Further, as compared with the first embodiment, the cycle of the drive current supplied to the stepping motor 7 is reduced, and the rotation speed of the stepping motor 7 is reduced less frequently. Therefore, the influence on the drive of the focusing lens 1d becomes smaller.

Next, the third and fourth embodiments of this embodiment will be described. FIG. 2 is a functional block diagram of a video camera including the lens driving device according to the third and fourth embodiments of the present invention. In the figure, reference numeral 17 is a current selector switch for switching the magnitude of the current supplied by the stepping motor drive circuit 8 to the stepping motor 7. Since the other constituents are the same as those of FIG. 1 showing the first and second embodiments, detailed description will be omitted.

The operation of the third embodiment will be described here. Similar to the first embodiment, the microcomputer is used every time the position change of the focusing lens 1b is started, whether the hill-climbing auto focus is performed or the focus position change accompanying the movement of the zoom lens 1b is corrected. Reference numeral 9 controls the current changeover switch 17 to increase the magnitude of the drive current supplied to the stepping motor 7 by the stepping motor drive circuit 8 for a predetermined period. Therefore, during that time, the driving torque of the stepping motor 7 increases, so that even if the lens biting state occurs, it is possible to easily get out of this state.

Next, the operation of the fourth embodiment will be described. Although the functional block diagram is the same as that of the third embodiment, the current changeover switch 16 is controlled every time the power supply device 14 is activated and the power supply is started. That is, since the driving torque of the stepping motor 7 increases each time the power is supplied, even if the lens jamming state occurs, it is possible to easily get out of the state. Further, as compared with the first embodiment, the magnitude of the drive current supplied to the stepping motor 7 increases, the power consumption increases, and the load on the stepping motor 7 increases less frequently. Therefore, the influence on the drive of the focusing lens 1d becomes smaller.

[0024]

According to the present invention, since the torque of the stepping motor for driving the lens is increased at the start of driving or when the power is turned on, even if the lens is caught, the lens driving can be easily escaped from the state. A device can be provided and its effect is great.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing first and second embodiments of the present invention.

FIG. 2 is a functional block diagram showing third and fourth embodiments of the present invention.

FIG. 3 is an explanatory diagram showing a lens driving device.

FIG. 4 is an explanatory diagram showing an inner focus type lens unit.

[Explanation of symbols]

 1 Lens Unit 1d Focusing Lens 3 Image Sensor 7 Stepping Motor 8 Stepping Motor Drive Circuit 9 Microcomputer 14 Power Supply Device 15 Power Switch 16 Cycle Change Switch 17 Current Change Switch

[Procedure amendment]

[Submission date] February 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

The inner focus type lens unit having a zoom correction lens is composed of a front lens 41, a zoom lens 42, a zoom correction lens 43, and a focus lens 44, as shown in FIG. 4A. The zoom lens 42 moves from the wide (W) side to the tele (T) side and from the T side to the W side. It should be noted that the zoom correction lens 43 moves at a certain part of the zoom lens 42 on the W side. Further, the focusing lens 44 moves from the near point side to the infinite side and from the infinite side to the near point side by driving a stepping motor (not shown).

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

As a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, a power supply device for supplying power to the driving means, and a start-up operation of the power supply device. Initial control means for controlling the drive circuit to reduce the cycle of the drive pulse for a predetermined period to drive the stepping motor.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Further, as a lens driving device, a stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, a power supply device for supplying power to the driving means, and a start-up operation of the power supply device. Initial control means for controlling the drive circuit to increase the magnitude of the drive pulse for a predetermined period to drive the stepping motor.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

Next, the operation of the first embodiment will be described. The focus position changes when the distance between the subject and the video camera changes. Therefore, the microcomputer 9 controls the stepping motor drive circuit 8 so that the focus evaluation value, which is the integrated value of the high frequency components of the video signal supplied by the integration circuit 13, becomes maximum, and drives the stepping motor 7 to focus. Move the lens to climb the mountain and perform auto focus. Since the lens unit 1 is of the inner focus type, the focus position changes when the zoom lens 1b moves. Therefore, the microcomputer 9 detects the position of the zoom lens 1b by the zoom encoder 11, and according to the detection result, the stepping motor drive circuit 8
Is controlled to drive the stepping motor 7 to move the focusing lens 1d.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

In any case, the microcomputer 9 controls the cycle changeover switch 16 every time the position change of the focusing lens 1d is started, and the stepping motor drive circuit 8 supplies it to the stepping motor 7. The cycle of the drive current is reduced for a predetermined period. Therefore,
During that time, the driving torque of the stepping motor 7 increases, so that even if a lens biting state occurs, it is possible to easily get out of this state.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

The operation of the third embodiment will be described here. As in the first embodiment, the microcomputer is used every time the position change of the focusing lens 1d is started, whether the hill-climbing autofocus is performed or the focus position change accompanying the movement of the zoom lens 1b is corrected. Reference numeral 9 controls the current changeover switch 17 to increase the magnitude of the drive current supplied to the stepping motor 7 by the stepping motor drive circuit 8 for a predetermined period. Therefore, during that time, the driving torque of the stepping motor 7 increases, so that even if the lens biting state occurs, it is possible to easily get out of this state.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Next, the operation of the fourth embodiment will be described. Although the functional block diagram is the same as that of the third embodiment, the current changeover switch 17 is controlled every time the power supply device 14 is activated and power supply is started. That is, since the driving torque of the stepping motor 7 increases each time the power is supplied, even if the lens jamming state occurs, it is possible to easily get out of the state. Further, as compared with the first embodiment, the magnitude of the drive current supplied to the stepping motor 7 increases, the power consumption increases, and the load on the stepping motor 7 increases less frequently. Therefore, the influence on the drive of the focusing lens 1d becomes smaller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03B 3/10 13/34 G03B 3/10

Claims (4)

[Claims] 1. A stepping motor for driving a lens, a drive means for supplying a drive pulse to the stepping motor, and a cycle control means for controlling the drive means and reducing the cycle of the drive pulse for a predetermined period at the start of driving. ,
A lens driving device comprising: 2. A stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, and a power supply device for supplying power to the driving means.
An initial control unit that controls the drive circuit to reduce the cycle of the drive pulse for a predetermined period to drive the stepping motor at the start of operation of the power supply device. 3. A stepping motor for driving a lens, a driving means for supplying a driving pulse to the stepping motor, and a torque control means for controlling the driving means and increasing the magnitude of the driving pulse for a predetermined period at the start of driving. A lens driving device comprising: 4. A stepping motor for driving a lens, drive means for supplying a drive pulse to the stepping motor, and a power supply device for supplying power to the drive means.
An initial control unit that controls the drive circuit to increase the magnitude of the drive pulse for a predetermined period to drive the stepping motor at the start of the operation of the power supply device.