JPS59101608A - drive device - Google Patents

Abstract

PURPOSE:To lighten a lens driving of a manual operation time and to improve the manual operability without making a structure complicated by setting a friction contact of a fixed body and a moving body of the manual operation time to a dynamical friction state, reducing a coefficient of friction, and also reducing a contact area. CONSTITUTION:When an electrical operation/manual operation changeover switch 31 is turned on, and a manual driving is selected, an electrical operation/manual operation switching circuit 36 outputs a switching signal of a low level, therefore, an output of an OR gate 47 becomes a high level, and a switching transistor 54 is turned on. On the other hand, an output of an AND gate 48 becomes a low level, and a switching transistor 53 is turned off. Accordingly, high frequency power is supplied to only an electrostrictive element 3a. Therefore, a standing oscillatory wave is generated in a fixed body 2, and a friction torque of the fixed body 2 and a distance adjusting ring 21 becomes small. When the electrical operation/manual operation changeover switch 31 is turned off, and the electrical driving is selected, the electrical operation/manual operation switching circuit 36 outputs a switching signal of a high level, therefore, the AND gate 48 is closed. This switching signal is inverted by an invertor 37, becomes a low level, and it is inputted to an input terminal C of a distance measuring circuit 35.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a vibration wave motor that utilizes mechanical vibration waves produced by electro-mechanical energy conversion means such as electrostrictive elements and magnetostrictive elements to improve the performance of cameras, video cameras, 8 mm cameras, etc. The present invention relates to a device for driving a lens.

As already known from Japanese Patent Laid-Open No. 52-29192, the vibration wave motor brings a fixed body and a moving body into frictional contact, and connects at least one of them to the electrical-mechanical energy conversion element itself or It is composed of an elastic vibrating body that includes an electro-mechanical energy conversion element, and by applying high-frequency electrical energy above the audible frequency to the electro-mechanical energy conversion element, mechanical vibration energy is generated and the moving body is frictionally moved in one direction. It is what drives it.

Among such vibration wave motors, the present invention particularly uses a type of vibration wave motor that generates bending vibration on the frictional contact surface between a fixed body and a movable body, and uses the traveling vibration wave to frictionally drive the movable body. .

Conventionally, attempts have been made to apply vibration wave motors to lens drives, but these have had the following problems. That is, in terms of lens drive, in addition to electric drive in which the lens is driven by the force of a vibration wave motor, manual drive in which the photographer drives the lens by his or her own power is strongly desired. However, in a vibration wave motor, there is strong frictional contact between the fixed body and the moving body,
The driving force is transmitted through contact between the seats. Therefore, in order to move the moving body when it is not driven, a large force exceeding the frictional force is required. That is, when driving the lens manually, a torque greater than the friction torque is required, and in order to reduce the torque and improve operability, a clutch mechanism or the like is required. This complicates the structure and is disadvantageous in terms of cost.

An object of the present invention is to solve the above-mentioned problems, and to make the lens drive during manual operation lighter and to improve manual operability without complicating the structure. The goal is to provide the following.

To achieve this object, the present invention provides an electric-to-mechanical energy conversion means that generates a traveling vibration wave in the electric-to-manual switching means and the electric-to-mechanical energy conversion means in the case of electric switching; A control means for generating a standing oscillating wave is provided in the motor, so that the frictional contact between the fixed body and the moving body during manual operation is made into a state of dynamic friction, thereby reducing the coefficient of friction and the contact area. shall be.

Before explaining the present invention in detail, the driving principle of a vibration wave motor (also called a piezoelectric motor or an ultrasonic motor) will be explained with reference to FIG.

In FIG. 1, 1 is a moving body pressurized with force F, 2
is a fixed body that performs elastic vibration by an electrostrictive element, and the X axis is the direction on the surface of the fixed body 2, and the Z axis is the normal direction thereof. When bending vibration is applied to the surface of the fixed body 2 by the electrostrictive element, a traveling vibration wave is generated and propagates on the surface of the fixed body 2. This traveling vibration wave 0. ′ is a surface wave accompanied by longitudinal waves and transverse waves, and the motion of the mass point follows an elliptical orbit. Focusing on mass point A, the vertical amplitude U and the horizontal excavation l
It is performing an elliptical motion of ll51W, and if the traveling direction of the surface wave is the X-axis direction, the elliptical motion is counterclockwise. This surface wave has vertices A, A'... for each wavelength, and its apex velocity is only the X component, v=2πfu(
f is the frequency).

Therefore, when the surface of the moving body 1 is brought into frictional contact with the surface of the fixed body 2, the surface of the moving body l contacts only the vertices A, A'..., so the moving body] is moved in the direction of the arrow N due to the frictional force. driven by

The speed of the moving body 1 is proportional to the frequency f. Furthermore, because of the I-stroke drive due to pressurized contact, it depends not only on the longitudinal amplitude U but also on the lateral amplitude W. That is, the speed of the moving body 1 is proportional to the magnitude of the elliptical motion. Therefore, the speed of the moving body 1 is proportional to the voltage applied to the electrostrictive element.

FIG. 2 is an exploded view showing the basic configuration of the vibration wave motor used in the present invention. Hard rubber 1a is bonded to the annular moving body 1 to facilitate frictional contact. The annular fixed body 2 has electrostrictive elements 3a forming two groups.
, 3b are glued. When the electrostrictive elements 3a and 3b operate independently, they are placed in a position where the fixed body 2 resonates, that is, a standing vibration wave exists, and the electrostrictive elements (-3a) The felt 4 is arranged so that the existing vibration wavelength and the standing vibration wavelength caused by the electrostrictive element 3b are equal to each other and are out of phase by 90° (physical position is shifted by 1 wavelength/4). The support body 5 supports the fixed body 2, the sound elements 3a and 3b, and the felt 4.

FIG. 3 is a diagram illustrating the generation of traveling vibration waves and standing vibration waves. For the sake of explanation, the electrostrictive elements 3a and 3b are not arranged as shown in FIG. 2, but are arranged alternately, but they satisfy the same conditions as above and are equivalent arrangements. The driving power supply 6 is V
=V(, sinωt is supplied. Electrostrictive element 3
A is supplied with voltage V directly from the drive power source 6 via line 7.

sinωt is applied to the electrostrictive element 3b, and a voltage V□ 5in (ωt±π/
2) is applied. Voltage V(,5in(ωt±π/2)
The direction of movement can be changed depending on the direction in which the moving body 1 is moved.

A to A in Figure S3 are voltage V. The state of the vibration wave is shown when 5 inches (ω = 1π/2) is applied. A is a state where the standing vibration wave 10 is generated only by the electrostrictive element 3a,
The opening shows a state in which a standing vibration wave 11 with a 90' phase delay is generated only by the electrostrictive element 3b. Haruji operates two electrostrictive elements 3a and 3b at the same time,
A state in which a traveling vibration wave 12 is generated is shown. C is time t=o+2nπ/ω, 2 is time t=π/2ω+2nπ/
ω, ho is time t=π/ω+2nπ/ω, to is 3π/2ω
The phase of the traveling vibration wave 12 of +2nπ/ω is shown. The traveling vibration wave 12 travels to the right in FIG.
Any mass point on the frictional contact surface performs an elliptic motion in the counterclockwise direction. Therefore, the moving body 1 moves to the left.

b. In the state where the standing vibration wave 10.11 of the mouth is generated, the mass points other than the nodes on the frictional contact surface of the fixed body 2 only exhibit transverse vibration, that is, vertical movement in FIG. 3.

Therefore, the frictional contact between the movable body 1 and the fixed body 2 is not a static friction state but a dynamic friction state, and the friction coefficient is small and the contact area is also small.

Therefore, when moving the movable body 1 manually, it can be moved with a small force.

FIG. 4 shows the structure of a zoom lens driving device according to an embodiment of the present invention. Components similar to those in FIG. 2 are designated by the same reference numerals.

A mounting member 14 such as a bayonet or screw mount for mounting on the camera is provided at the rear end of the fixed barrel 13 of the lens barrel. A straight groove 13a is provided in the fixed barrel 13 in the optical axis direction. The lens holding cylinders 15 and 16 are fitted inside the fixed cylinder 13 and hold a lens optical system 17 that performs a magnification change function and an aberration correction function accompanying the magnification change. Pins 15a and 16a are installed in each lens holding barrel 15 and 16, and these pins 15a and 16a pass through the straight groove 13a and connect to the cam groove 1 of the cam barrel 18 fitted on the outer periphery of the fixed barrel 13.
8a and 18b. The lens holding cylinder 19 holds the focusing lens optical system 20, and has a threaded portion 19a on its outer periphery that is screwed into the lens holding cylinder 15. The cylindrical flange 19b is
It is fitted into a straight groove 21a formed on the inner peripheral surface of the distance adjustment ring 21 in parallel to the optical axis direction. A grip portion 21b is provided at the tip of the distance adjustment ring 21. The friction contact portion 21c of the distance adjustment ring 21 corresponds to the movable body 1 in FIG. 2, and is pressed against the fixed body 2 by a ring leaf spring 22. The base cylinder 23 is integrally fixed to the fixed body 13 with screws (not shown), and the fixed body 2,
The electrostrictive elements 3a, 3b and the felt 4 are supported.

An outer cylinder 24 is screwed to the base cylinder 23, and a first ring 25 and a second ring 26 for bearings are attached to the inside of the outer cylinder 24. That is, the first ring 25 is connected to the friction contact portion 21c of the distance adjustment ring 21 by the ring plate spring 22 via the bearing pawl 27.
be forced to. The second ring 26 is attached by being screwed into the inner circumferential surface of the outer cylinder 24, and a V-shaped circumferential groove is formed at the joint between the first ring 25 and the second ring 26. A bearing hole 28 is held between the groove and a substantially U-shaped circumferential groove formed on the outer peripheral surface of the distance adjustment ring 21. Thereby, the distance adjustment ring 21 is rotatably attached to the outer cylinder 24, and the rotatable jf friction contact of the repulsion contact portion jlc with the fixed body 2 is ensured.

The code plate 29 has comb-like electrodes, and the outer cylinder 24
The slider 30 attached to the inner wall surface of the distance adjustment ring 21 and fixed to the distance adjustment ring 21 slides on the comb-like electrodes, thereby changing the amount of rotation of the distance adjustment ring 21, that is, the adjustment;;, +, of the Tagawa lens optics 20. A displacement monitor signal is generated which consists of a number of pulses corresponding to the displacement.

An electric manual changeover switch 31 is provided on the outer cylinder 24, and its contact piece 32 is attached on the base cylinder 23. Operation pin 33
is attached to the cam barrel 18, and the cam barrel 18 is rotated by turning it around the optical axis from the outside of the base barrel 23. When the cam cylinder 18 rotates, the cam grooves 18a and 18b engage the pin 15.
Since the lenses a and 16a are moved along the straight groove 13a, the lens holding cylinders 15 and 16 are moved in the direction of the optical axis, resulting in a variable magnification effect.
and an aberration correction action.

FIG. 5 shows a circuit of one embodiment of the present invention. The autofocus light receiver 34 is connected to the distance measuring circuit 35 using, for example, a charge-coupled device. Output terminal A of the distance measuring circuit 35 outputs a high-level drive signal or a low-level stop signal to the vibration wave motor, and output terminal B outputs a high-level near-side drive direction signal or a low-level infinity-side drive signal. A direction signal is output, a switching signal is inputted to the input terminal C via the inverter 37 from the electric manual switching circuit 36, and a movement amount monitor signal is inputted to the input terminal C from the monitor signal generation circuit 38 via the chattering absorption circuit 39. enters. The first manual switching circuit 36 consists of an electric manual switching switch 31 and a resistor 40.
, a slider 30 and a resistor 41. Pulse generation circuit 4
2i) Tatsuki 43, frequency divider with frequency division ratio 1/2 44.45
and an inno-hater 46, and outputs pulses with a 90° phase difference from a frequency divider 44.45. 47 is an OR gate, 48 is an AND gate, and 49 is an exclusive OR gate. The alternative OR gate 49 is the l of the ranging circuit 35.
IT power ☆ 111 Input from child B is // level l + 1
The phase of the knock pulse of the frequency divider 45 with respect to the pulse of Rg 44 is advanced by 90', and the low level 11
It is assumed that the ¥ number is delayed by 90 degrees.

The drive control circuit 50 is a circuit for controlling the drive of the electrostrictive elements 3a and 3b, and is composed of two push-pull circuits 51 and 52 each consisting of a transistor, a resistor, and an inverter, and a switching transistor 53 and 54. The switching transistors 53 and 54 are connected to a power source via a resistor 55 and a lens drive power switch (not shown).

Next, the operation of the embodiment shown in FIG. 4.5 will be explained. When the lens drive power switch (not shown) is turned on, the electric manual switching circuit 36, the impark 37,
OR gate 47, AND gate 48, exclusive OR gate 491. <Power is supplied to the pulse generation circuit 42 and the drive control circuit 50, and the pulse generation circuit 42 starts operating.

When the electric manual switching switch 31 is turned off and electric drive is selected, the electric manual switching circuit 36 outputs a high level switching signal, so the AND gate 48 is opened. Further, this switching signal l is inverted by the inverter 37, becomes low level, and is input to the input terminal C of the distance measuring circuit 35.

When the first stroke of the release button consisting of two strokes is pressed for photographing operation of the camera, a photometry calculation operation is started. The distance measuring circuit 35 determines that it is electrically driven by inputting the low-level 9-node signal to the input terminal C, starts automatic focusing operation, and automatically adjusts the focusing area; 1. Set narrow 'I'i2) for % points.

The light receiver 34 receives reflected light from the subject, and the distance measuring circuit 3
5 is a known controller I based on the wave force body information from the light receiver 34.
- Detects the focusing error based on the last detection method, shift detection method, etc., and calculates the lens drive amount and drive direction. The lens driving amount is preset by a counter (not shown) in the distance measuring circuit 35. Assuming that a high-level drive signal is output from output terminal A and that the subject is close,
Output terminal B outputs a high-level nearby drive direction signal. Therefore, the ORK 47 and ANDK 48 both output high level signals, turning on the switching transistors 53 and 54. Therefore, power is supplied to the push-pull circuits 51 and 52. The pulse generation circuit 42 is in operation, and the pulses from the frequency divider 44 directly control the push-pull circuit 52, so the electrostrictive element 3b
high-frequency power is applied to. The pulse of the frequency divider 45 is inverted by the exclusive orcate circuit 49 and has a phase lead of 90' with respect to the pulse of the frequency divider 44, and controls the push-pull circuit 51, so that the pulse of the frequency divider 45 is inverted by the exclusive OR gate 49, and controls the push-pull circuit 51.
° High frequency power with advanced phase is given. This results in
A traveling vibration wave 12 is generated in the fixed body 2, and the distance adjustment ring 21 is rotated in the focusing direction. As a result, the lens holding tube 19
rotates while being screwed together with the lens holding cylinder 15, so it moves in the drawing direction and reaches the in-focus area.

As the distance adjustment ring 21 rotates, the slider 30 slides on the code plate 29 and generates a movement amount monitor signal with a pulse number corresponding to the movement amount of the lens. This movement amount monitor signal is input to the input terminal of the distance measuring circuit 35, and the lens driving amount registered in the counter is subtracted. When the value of the counter becomes zero, a low level stop signal is output from the output terminal A, and the outputs of the OR gate 47 and the AND gate 48 are inverted to low level, so that the switching transistor 53.5
4 is turned off, the electrostrictive elements 3a and 3b are cut off from the power supply, and the driving of the distance adjustment ring 21 is stopped. Here again, distance measurement is performed by the light receiver 34 and the distance measurement circuit 35,
If the focusing error is within the in-focus range, the in-focus display will be displayed. Go! , when the lens is not in the range, the lens is driven again in the same manner as described above.

When the subject is at infinity, the output terminal B of the distance measuring circuit 35 outputs a low-level infinity drive direction signal, so the exclusive OR gate 49 passes the pulse of the frequency divider 45 as it is and divides it. It is assumed that the phase is delayed by 90 degrees from the pulse of the frequency generator 44. Therefore, the electrostrictive elements 3a and 3b generate traveling vibration waves that travel in opposite directions, the distance adjustment ring 21 rotates in the opposite direction, and the lens holding cylinder 19 is moved in the retracting direction.

When the electric manual changeover switch 31 is turned on and manual drive is selected, the electric manual changeover circuit 36 outputs a low level switching signal, so the output of the OR gate 47 becomes high level, turning on the switching transistor 54. Make it. On the other hand, the output of the AND gate 48 becomes low level, turning off the switching transistor 53. Therefore, high frequency power is not supplied to the electrostrictive element 3b, but only to the electrostrictive element 3a. Therefore, a standing vibration wave 10 is generated in the fixed body 2, and the friction torque between the fixed body 2 and the distance adjustment ring 21 is reduced. Therefore, by holding the grip portion 21b slightly exposed from the tip of the outer cylinder 24 and turning the distance adjustment ring 21, it will turn lightly with a small manual torque, and the lens holding cylinder 19 will be moved in the optical axis direction.

The distance measuring circuit 35 determines that the manual drive is performed by inputting the /\I level switching signal to the input terminal C, sets the width of the wide focusing range for manual driving, and adjusts the focusing lens optics. When the system 20 reaches the in-focus area, an in-focus display is performed.

According to this embodiment, during manual focus adjustment, the distance adjustment ring 21
can be moved easily, improving manual operability. Additionally, the following advantages of vibration wave motors can be utilized in cameras.

(-1) Since it does not have a winding, it is easy to manufacture and does not require much manpower.

(2) The amount of expensive materials used can be reduced.

(3) Dimensions are smaller and can be made into a flat structure or elongated shape.

(4) A low-speed motor can be configured, and a speed reduction mechanism is not required.

(5) It has large starting torque and small moment of inertia.

In the illustrated embodiment, the electrostrictive elements 3a, 3b correspond to the electro-mechanical energy conversion means of the present invention, and the impark 37.
The OR gate 47, the AT gate 48, and the switching transistors 53 and 54 correspond to control means.

In the illustrated embodiment, a plurality of electrostrictive elements 3a and 3b are used, or one electrostrictive element may be polarized into a plurality of elements. Further, the electrostrictive element is connected to the friction contact portion 21 of the distance adjustment ring 21.
c, or both the fixed body 2 and the friction contact portion 21c. Furthermore, the fixed body 2 itself may be composed of an electrostrictive element. The optimal frequency of the vibration wave produced by the electrostrictive element is in the super-j near wave region.

Error detection is limited to an optical method; an ultrasonic method may also be used.

The present invention is suitable for manual operation of a zoom lens drive, that is, a power zoom drive, instead of being used for focusing drive of a lens.

As explained above, according to the present invention, a traveling vibration wave is generated in the electric-to-mechanical energy conversion means in the electric-to-manual switching means and the electric-to-mechanical energy conversion means at the time of electric switching; By providing a control means that generates vibration waves, the frictional contact between the fixed body and the movable body during manual operation is made into a state of dynamic friction, reducing the coefficient of friction and the contact area, which reduces the complexity of the structure. without making it
It is possible to lighten the lens drive during manual operation and improve manual operability.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the driving principle of the vibration wave motor, Figure 2 is an exploded view showing the basic configuration of the vibration wave motor used in the present invention, and Figure 3 is the progression in the vibration wave motor shown in Figure 2. Diagram 4 explaining the generation of vibration waves and standing vibration waves
The figure is a sectional view showing one embodiment of the present invention, and FIG. 5 is a circuit diagram as well. 1...Moving body, 2...Fixed body, 3a,
3b... Electrostrictive element, 10.11... Standing vibration wave, 12... Traveling vibration wave, 13...
・・Fixed barrel, 15.16・・・Lens holding tube, 1
9... Lens holding tube, 20... Focusing lens optical system, 21... Distance adjustment ring, 23...
...Base cylinder, 24...Outer cylinder, 31...
・Electric manual changeover switch, 32... Contact piece, 34
......Receiver, 35...41 distance circuit,
36...Electric manual switching circuit, 37...
Inverter, 42...Pulse generation circuit, 44.
45... Frequency divider, 47... OR gate, 48... AND gate, 49... Exclusive OR gate, 50... Drive control circuit, 51
．． 52...Push-pull circuit, 53.54...
...Switching transistor. Patent applicant “Canon Co., Ltd.

Claims (1)

[Claims] /, using a vibration wave motor consisting of a fixed body, a movable body that makes frictional contact with the fixed body, and an electro-mechanical energy conversion means that is included in at least one of the fixed body and the movable body and generates a traveling vibration wave. In the lens driving device, the electric-to-mechanical energy conversion means generates a traveling vibration wave during electric switching, and the electric-to-mechanical energy conversion means generates a standing vibration during manual switching. 1. A lens driving device using a vibration wave motor, characterized in that it is provided with a control means for generating waves.