JPH0472471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device using a vibration wave motor that utilizes mechanical vibration waves produced by electro-mechanical energy converting means such as an electrostrictive element or a magnetostrictive element.

As already known from Japanese Unexamined Patent Publication No. 52-29192, a vibration wave motor brings a fixed body and a moving body into frictional contact, and converts the electro-mechanical energy conversion element itself of at least one of them, or is composed of an elastic vibrating body containing an electro-mechanical energy conversion element,
By applying high-frequency electrical energy above the audible frequency to an electro-mechanical energy conversion element, mechanical vibration energy is generated to frictionally drive a moving body in one direction.

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

Conventionally, the method for starting a vibration wave motor has been to generate a traveling vibration wave using a drive start signal, similar to DC motors and AC motors. However, with this startup method, the startup characteristics were not good. Here, in order to make it easier to understand, 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 by a force F, 2 is a fixed body that vibrates elastically by an electrostrictive element, the x-axis is directed in the direction on the surface of the fixed body 2, and the z-axis is Line direction. When bending vibration is applied to the surface of the fixed body 2 by the electrostrictive element, a traveling vibration wave is generated,
It propagates on the surface of the fixed body 2. This traveling vibrational wave is a surface wave accompanied by longitudinal waves and transverse waves, and the motion of its mass point follows an elliptical orbit. Focusing on the mass point A, it is performing an elliptical motion with a longitudinal amplitude u and a lateral amplitude w, 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, and is v=2πfu (f is the frequency). Therefore, when the surface of the movable body 1 is brought into frictional contact with the surface of the fixed body 2, the surface of the movable body 1 contacts only the vertices A, A'..., so the movable body 1 is driven in the direction of the arrow N by the frictional force. be done.

The speed of the moving body 1 is proportional to the frequency f. Also,
Due to the frictional drive due to pressure contact, it depends not only on the longitudinal amplitude u but also on the transverse 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.

In the conventional startup method, a traveling vibration wave is generated by a drive start signal, and when the state is changed from a stationary state to an operating state, the elliptical motion gradually increases due to the vibration energy of the electrostrictive element during the transition period when the stationary state is reached. After a period of time, a steady state is reached. It takes a certain amount of time for the vibration energy of the electrostrictive element to be converted from a zero state into longitudinal vibration energy and transverse vibration energy of stable traveling vibration waves.

An object of the present invention is to provide a vibration wave motor drive device that can solve the above-mentioned problems and improve startup characteristics at startup.

In order to achieve this object, the present invention is a vibration wave motor drive device having a control circuit, wherein the vibration wave motor has a vibrating body and a driven body, and the vibrating body generates electrical-mechanical energy. Vibration waves are generated on the surface of the vibrating body by excitation by the conversion element, and the driven body is pressed against the surface of the vibrating body and driven, and the control circuit drives the electro-mechanical energy conversion element with an alternating voltage. This method generates a standing vibration wave in the vibrating body, and then generates a traveling vibration wave.Thus, before the traveling vibration wave drives the driven body, the generation of the standing vibration wave causes the vibration body to vibrate. It is characterized by storing energy.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIGS. 2 and 3 are structural exploded views showing an example of a vibration wave motor embodying the present invention, and diagrams showing electrical connections and states of generation of traveling vibration waves and standing vibration waves. Components similar to those in FIG. 1 are designated by the same reference numerals.

In FIG. 2, a hard rubber 1 is used to facilitate frictional contact with an annular moving body 1 as a driven body.
a is glued. Electrostrictive elements 3a and 3b as electro-mechanical energy conversion elements forming two groups are adhered to the annular fixed body 2, and a vibrating body 96 is constituted by the fixed body 2 and the electrostrictive elements 3a and 3b. be done. Electrostrictive elements 3a and 3b as electro-mechanical energy conversion elements forming two groups are bonded to the annular fixed body 2 for vibration. When the electrostrictive elements 3a and 3b operate independently, they are arranged in a state where the fixed body 2 resonates, that is, in a position where a standing vibration wave exists, and the electrostrictive elements 3a and 3b are arranged in a position where the standing vibration wavelength is The standing vibration wavelength caused by the electrostrictive element 3b becomes equal, and the phase shifts by 90° (1 wavelength/
4).
The felt 4 absorbs vibrations on the surface of the fixed body 2 opposite to the frictional contact surface. The support body 5 supports the fixed body 2, the electrostrictive elements 3a and 3b, and the felt 4.

In FIG. 3, electrostrictive elements 3a and 3b are used for explanation purposes.
Although they are not arranged as in FIG. 2 but are arranged alternately, they satisfy the same conditions as above and are an equivalent arrangement. The driving power supply 6 supplies a voltage of V=V ₀ sinωt. A voltage V 0 sinωt is directly applied to the electrostrictive element 3a from the driving power source 6 via a line 8 via a start switch 7, and a voltage V ₀ sinωt is applied via a line 11 to the electrostrictive element 3b via a power switch 9 and a 90° phase shifter 10. A voltage V ₀ sinωt (ωt±π/2) is applied. The ± of the voltage V ₀ sinωt (ωt±π/2) is switched depending on the direction in which the moving body 1 is moved. 3A to 3F show the state of vibration waves when a voltage V ₀ sinωt (ωt−π/2) is applied. A is a state in which the standing vibration wave 12 is generated only by the electrostrictive element 3a, B is a state in which a standing vibration wave 13 with a 90° phase delay is generated only by the electrostrictive element 3b,
are shown respectively. H~N are two electrostrictive elements 3a,
3b are operated simultaneously to generate a traveling vibration wave 14. Ha is time t=0+2nπ/
ω, D is time t=π/ω+2nπ/ω, E is time t
=π/ω+2nπ/ω, and F indicates the phase of the traveling vibration wave 14 of 3π/2ω+2nπ/ω, respectively. The traveling vibration wave 14 travels to the right in FIG. 3, but the mass point on the frictional contact surface of the fixed body 2 performs an elliptical motion in a counterclockwise direction.
Therefore, the moving body 1 moves to the left.

First, when the power switch 9 is turned on, only the electrostrictive element 3b operates, and only the standing vibration wave 13 (b) is generated. In this state, the mass points other than the nodes on the frictional contact surface of the fixed body 2 experience only lateral vibration, that is, vertical movement in FIG. 3. As a result, vibration energy is stored in the fixed body 2, and preparations for activation are made. Next, when the start switch 7 is turned on, the electrostrictive element 3a also generates a standing vibration wave 12, which is combined with the standing vibration wave 13 to generate a traveling vibration wave 14. Since vibration energy is stored in the fixed body 2 before starting, the generation of the traveling vibration wave 14 rises quickly.

4 and 5 are an exploded structural view and a circuit diagram showing an example of an aperture unit to which the present invention is applied to the aperture drive of a camera. This diaphragm unit starts photometric calculations with the first stroke of the camera's release button, generates a standing oscillation wave 13, prepares to drive the diaphragm, and starts the photographing sequence with the second stroke, and generates a progressive vibration. wave 1
4 to drive the aperture. Second
Parts similar to those in the figure are designated by the same reference numerals.

In FIG. 4, a substrate 15 is fixed to a casing (not shown) at the base of the camera, and a plurality of pins 15b are implanted on the cylindrical portion 15a of the substrate 15, which serve as rotational fulcrums for aperture blades 16 (described later). . A code plate 17 having comb-shaped electrodes is attached to the substrate 15,
As the slider 19 attached to the rotating body 18 slides on the comb-like electrodes, an aperture monitor signal consisting of a number of pulses corresponding to the amount of rotation is generated. On the substrate 15 are a felt 4 and an electrostrictive element 3.
a, 3b, and the fixed body 2 are fixed. Rotating body 1
Reference numeral 8 corresponds to the movable body 1 in FIG. 2, and a plurality of pins 18a that come into frictional contact with the fixed body 2 and control the rotation of the aperture blades 16 are implanted thereon. The protrusion 18b turns on the open reset switch 20 attached to the substrate 15 when the aperture is opened.

Although only one aperture blade 16 is shown in FIG. 4 and the others are omitted, a plurality of aperture blades 16 are arranged between the rotary body 18 and the fixed cover 21 to form an aperture aperture on the rotary body 18. be done. Pins 18a and 18 are provided in the arc holes 16a and 16b of the aperture blade 16, respectively.
b is inserted. A steel ball 22 and a spacer 23 are interposed between the rotating body 18 and the fixed cover 21, and function as a thrust bearing. Fixed cover 21
is connected to the board 1 via a spring 25 by a plurality of screws 24.
It is fixed at 5. The rotating body 18 is rotatably pressed against the fixed body 2 via the steel ball 22 by the force of the spring 25 .

In FIG. 5, the photometric calculation circuit 26 includes a light receiver 27 that detects the amount of light incident from the subject through the open lens, an operational amplifier 28, a diode 29,
A resistor 30 that generates subject brightness information V _V0 through an open lens based on the output of the operational amplifier 28, a variable resistor 31 that generates film sensitivity information S _V , and a variable resistor that generates setting exposure information (for example, shutter time information Tv). 32, an operational amplifier 33 and an A/D converter 34 for calculating the aperture value _ΔAV .
The monitor signal generation circuit 35 includes a code plate 17, a slider 19, and a resistor 36 connected to a constant voltage power source. The chattering absorption circuit 37 absorbs the chattering component of the aperture monitor signal output from the monitor signal generation circuit 35, and its output side is connected to the input terminal I of the presettable down counter 38. The control signal generation circuit 39 consists of RS flip-flops 40 and 41, and receives a power signal P ₁ linked to the first stroke of the release button, an aperture activation signal P ₂ linked to the second stroke, and an exposure completion signal P ₃ . . Single pulse generation circuit 42
The output side is connected to the load terminal L of the presettable down counter 38. Pulse generation circuit 43
is an oscillator 44, and frequency dividers 45 and 46 with a frequency division ratio of 1/2.
and an inverter 47, and outputs pulses with a 90° phase difference from frequency dividers 45 and 46. 48～
50 is an AND gate, 51 is an OR gate, 52 is an exclusive OR gate, and 53 is a resistor connected to a power supply. The exclusive OR gate 52 controls the frequency divider 46 for the pulses of the frequency divider 45 when the input from the output terminal Q of the RS flip-flop 40 is at a high level.
Assume that the phase of the pulse is advanced by 90°, and when it is at low level, it is delayed by 90°.

The drive control circuit 54 is a circuit that controls the drive of the electrostrictive elements 3a and 3b, and includes two push-pull circuits 55 and 5 made up of transistors, resistors, and inverters.
6. Consisting of switching transistors 57, 58, etc. switching transistor 5
7 and 58 are connected to a power supply via a resistor 59.

Next, the operation of the aperture unit shown in FIGS. 4 and 5 will be explained.

When the first stroke of the release button is pressed for camera shooting operation, the power signal _P1 is activated.
It is input to the set input terminal S of the RS flip-flop 41 to put it in the set state. At the same time, the photometry calculation circuit 26, the pulse generation circuit 43, and the like start operating, and power is supplied to the drive control circuit 54 and the like. If the subject brightness is B _V and the open aperture value is A _V0 , the amount of light enters the receiver 27 through the open lens, so the output of the operational amplifier 28 causes the resistor 3 to
The object brightness information B _V0 generated at 0 is as follows.

B _V0 = B _V − A _V0 On the other hand, if the aperture value to be controlled is A _V , the aperture value ΔA _V can be obtained from the equation ΔA _V = A _V −A _V0 . When the apex calculation formula B _V +S _V =A _V +T _V is transformed using the above two formulas, the following formula is obtained.

(B _V −A _V0 ) + S _V −T _V = A _V −A _V0 = △A _V The operational amplifier 33 calculates this equation and determines the aperture value △A _V , that is, the number of aperture steps that should be narrowed down to move the aperture blades 16 to the open position. Output a signal. This signal is A/D
The converted value is converted into a digital value by the converter 34 and applied to the data terminal D of the presettable down counter 38.

Due to the high level output from the output terminal Q of the RS flip-flop 41, the output of the OR gate 51 is inverted to high level, turning on the switching transistor 58. On the other hand, due to the low level output from the output terminal of RS flip-flop 41, the output of AND gate 50 is held at low level, and switching transistor 57 remains off. Therefore, push-pull circuit 5
5 is not supplied with power, and the push-pull circuit 56
By supplying power only to the frequency dividing circuit 45 and controlling the push-pull circuit 56,
Only the electrostrictive element 3b performs a vibratory motion, and a standing vibration wave 13 is generated in the fixed body 2. As a result, vibration energy is stored in the fixed body 2 without the rotating body 18 moving, and preparations for starting are made.

When the second stroke of the release button is pressed, an aperture activation signal _P2 is input, setting the RS flip-flop 40 and resetting the RS flip-flop 41 at the same time. As a result, the high level signal applied to the reset terminal R of the presettable down counter 38 is inverted to low level, and the reset is released. At the same time, the single pulse generating circuit 42 operates and applies a single pulse to the load terminal L, so that the output of the A/D converter 34 is preset in the presettable down counter 38. The high level signal at the output terminal Q of the RS flip-flop 40 causes the AND gate 49 to
and the output of the OR gate 51 becomes high level,
The high level signal at the output terminal of the RS flip-flop 41 causes the output of the AND gate 50 to go high, so that both switching transistors 57 and 58 are turned on. Therefore, driving voltages having a phase difference of 90° are supplied to the electrostrictive elements 3a and 3b, and a traveling vibration wave 14 is quickly generated in the fixed body 2. As a result, the rotating body 18 rotates, and the aperture blades 16 are narrowed down from the open position toward the small aperture. An aperture monitor signal with a number of pulses corresponding to the rotation angle of the rotating body 18 is input from the monitor signal generation circuit 35 to the input terminal of the presettable down counter 38 via the chattering absorption circuit 37, and the presettable down counter 38 receives the preset value. Subtract from. When the count value is made zero, a high level signal is output from the carry terminal C, and the outputs of the AND gates 49 and 50 and the OR gate 51 are set to low level, so that the switching transistor 5
7 and 58 are turned off, power supply to the electrostrictive elements 3a and 3b is stopped, the rotating body 18 is stopped, and the aperture blade 16 forms an aperture diameter. The aperture value A _V at this time is from the open aperture value A _V0 to the aperture value A _V
The value is narrowed down by (A _V0 +△A _V ).

When the exposure of the film is completed by the shutter operation, the exposure completion signal _P3 is sent to the RS flip-flop 4.
Reset to 0. At this time, since the open reset switch 20 is off, the output of the AND gate 48 is inverted to high level, and the outputs of the OR gate 51 and the AND gate 50 are also inverted to high level. Therefore, the switching transistors 57, 5
8 are both turned on, the electrostrictive elements 3a and 3b perform vibrational motion, and generate a traveling vibration wave in the fixed body 2. At this time, the phase of the pulse from the frequency divider 46 is delayed by 90 degrees with respect to the pulse from the frequency divider 45 by the exclusive OR gate 52, so the traveling direction of the traveling vibration wave is reversed, and the rotating body 18 is apertured. The blade 16 rotates in the opening direction. When the switch rotates to the open position, the open reset switch 20 is turned on by the protrusion 18b of the rotating body 18, so the AND gate 48 is turned on.
The output returns to low level, and the electrostrictive elements 3a, 3b
The power supply to is cut off, and the rotating body 18 stops.

FIG. 6 is a perspective view showing an example of a shutter mechanism in which the present invention is applied to the shutter drive of a camera. 60 is a vibration wave motor for driving the rear blade;
It has substantially the same structure and electrical circuitry as shown in FIGS. A vibration wave motor for driving the leading blade is separately provided, but is omitted in FIG.

FIG. 6 shows the shutter mechanism when the camera is in a fully charged state. 61 is a winding shaft, 62 is a winding cam that rotates together with the winding shaft 61, and 63
A winding lever 66 is rotated to the right by a winding cam 62 to charge a mirror drive lever 64 against a main spring 65. A winding lever 66 is pivoted on the mirror drive lever 64 and is engaged with a mirror push lever 68 by a spring 67. A clutch 69 is biased to engage the mirror, 70 is a mirror pin that is pushed by the mirror push-up lever 68 and pushes up the mirror 69 against the mirror return spring 71, and 72 is a mirror 69 that is pushed up when the mirror 69 is pushed up. A switch that is turned on by the mirror pin 70 and causes the vibration wave motor 60 to generate a standing vibration wave for a certain period of time by a circuit not shown, and then generates a traveling vibration wave; 73 is a locking lever; 74 is a switch that operates the locking lever 73; energizing spring, 75
76 is a release magnet that normally attracts the armature and releases the armature when a current flows, and 76 is a type that rotates by the force of a spring 77 when the release magnet 75 is activated and locks the locking lever 73. The magnet lever 78 releases the lock of the mirror drive lever 64 by turning to the right, and the set lever 79 releases the clutch 66 and the mirror push lever 6 by hitting the tip of the clutch 66 in the direction of the arrow.
A release lever 80 disengages from the mirror push-up lever 68 and rotates to the right against a spring 81, and an aperture drive lever 82 drives an aperture interlocking member (not shown) of the lens. Shutter base plate, 83 is the rear shutter blade, 84 is the front shutter blade, 8
5 is a trailing blade drive lever that supports the shutter trailing blade 83 together with a trailing blade auxiliary lever 86, and 87 is a trailing blade driving lever that supports the shutter trailing blade 84 together with a leading blade auxiliary lever 88.
This is the leading blade drive lever that supports the.

A rotating shaft 89 of the vibration wave motor 60 is connected to rotate the rear blade drive lever 85 . Similarly, the rotating shaft of the vibration wave motor for driving the leading blade is connected to the leading blade driving lever 87. The switch 90 is for generating a leading blade travel completion signal, and is turned on and off by a pin 91 provided on the leading blade auxiliary lever 88. When the leading blade travel is completed, the switch 90 is turned on and starts the vibration wave motor for starting the leading blade. make it stop. The leading blade reset switch 92 is turned on by a pin 91 when the shutter leading blade 84 is returned to the reset position after photographing is completed, and stops the vibration wave motor for driving the leading blade. A switch 93 for generating a trailing blade travel completion signal and a trailing blade reset switch 94 are similarly turned on and off by pins 95, and the vibration wave motor 6
Controls 0.

The following operation will be explained. When the shutter release is performed using the camera release button,
When the release magnet 75 is energized, the magnet lever 76 is released and rotated to the left by the spring 77. As a result, the locking lever 73 is moved by the spring 74.
The mirror drive lever 64 is then rotated to the right against the rotational force, and the mirror drive lever 64 is unlocked. The mirror drive lever 94 is connected to the main spring 65
At this time, the mirror push-up lever 68 is rotated to the left via the clutch 66, and the mirror 69 is raised. At the same time, the aperture drive lever 80 narrows down the aperture of the lens. Further, as the mirror 69 rises, the switch 72 is turned on, causing the vibration wave motor 60 and the vibration wave motor for driving the leading blade to first generate a standing vibration wave, and then generate a traveling vibration wave after a predetermined time period. Therefore, the leading blade driving lever 87 and the trailing blade driving lever 85 rotate, respectively, and drive the leading shutter blade 84 and the trailing shutter blade 83. When the switch 90 is turned on for the shutter leading blade 84 and the switch 93 is turned on for the shutter trailing blade 83, the respective vibration wave motors are stopped and the exposure is completed.

After photographing is completed, when winding is performed by the winding mechanism, each vibration wave motor rotates in the opposite direction to that during exposure, returning the shutter leading blade 84 and the shutter trailing blade 83 to the reset position. Also, the magnet lever 7 is set by the set lever 78.
6 is charged to the initial position, the winding lever 63 is rotated to the right by the rotation of the winding cam 62, and the mirror drive lever 64 is returned to the initial position where it is locked by the locking lever 73.

In the illustrated embodiment, the moving body 1 corresponds to the driven body of the present invention, the electrostrictive elements 3a and 3b correspond to electro-mechanical energy conversion elements, and the fixed body 2 and the electrostrictive elements 3a and 3b correspond to vibrating bodies. Equivalent to. Further, in FIG. 3, the drive power source 6, start switch 7, power switch 9, and 90° phase shifter 10 correspond to the control circuit of the present invention, and in FIG. 5, the control signal generation circuit 39, the pulse generation circuit 43 , AND gate 50, exclusive OR gate 53, and drive control circuit 54 correspond to the control circuit of the present invention.

Although a plurality of electrostrictive elements 3a and 3b are used in FIGS. 2 to 6, a single electrostrictive element may be polarized into a plurality of elements. Further, the electrostrictive element may be provided in the moving body 1 or may be provided in both the moving body 1 and the fixed body 2. Furthermore, the movable body 1 itself or the fixed body 2 itself may be constructed of an electrostrictive element. The optimal frequency of the vibration waves produced by the electrostrictive element is in the ultrasonic range.

In the aperture unit shown in Figures 4 and 5, a standing oscillating wave is generated in conjunction with the first stroke of the release button, and a standing guided wave is generated for a predetermined period of time in conjunction with the second stroke. After that, a traveling vibration wave may be generated.

As explained above, according to the present invention, the control circuit applies an alternating voltage to the electro-mechanical energy conversion element to generate a standing vibration wave in the vibrator, and then generates a traveling vibration wave in the vibrator. Since vibration energy is stored in the vibrating body by generating a standing vibration wave before the driven body is driven by the traveling vibration wave, it is possible to improve the start-up characteristics at startup.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the driving principle of a vibration wave motor, Fig. 2 is a structural exploded view showing an example of a vibration wave motor embodying the present invention, and Fig. 3 is a diagram illustrating its electrical connections, traveling vibration waves, and 4 is a structural exploded view showing an example of application of the present invention to the aperture drive of a camera, FIG. 5 is a circuit diagram, and FIG. 6 is a diagram showing the application of the present invention to the shutter drive of a camera. It is a perspective view showing an example of application. 1... Moving body (driven body), 2... Fixed body, 3
a, 3b... Electrostrictive element (electro-mechanical energy conversion element), 6... Driving power supply, 7... Starting switch,
9...Power switch, 10...90° phase shifter, 12,
13... Standing vibration wave, 14... Traveling vibration wave, 16
... Aperture blade, 18 ... Rotating body, 39 ... Control signal generation circuit, 40, 41 ... RS flip-flop, 43 ... Pulse generation circuit, 45, 46 ... Frequency divider, 54 ... Drive control circuit, 55, 56... Push-pull circuit, 57, 58... Switching transistor, 60... Vibration wave motor, 72... Switch, 96... Vibrating body.

Claims (1)

[Claims] 1. Control circuits 6, 7, 9, 10: 39, 43, 5
0, 52, 54, the vibration wave motor has a vibrating body 96 and a driven body 1, and the vibrating body 96 is connected to the electro-mechanical energy conversion elements 3a, 3b. Therefore, it is excited and generates a vibration wave on the surface, and the driven body 1 is pressed against the surface of the vibrating body 96 and driven. Control circuits 6, 7, 9, 10: 39, 43, 5
0, 52, and 54 are for vibration wave motors that drive the electro-mechanical energy conversion elements 3a and 3b with an alternating voltage to generate a standing vibration wave in the vibrating body 96, and then generate a traveling vibration wave. Drive device.