JPH06178563A - Driving circuit for surface wave motor - Google Patents

Abstract

PURPOSE:To put the waveform of an AC signal applied to the a surface wave motor in the shape of a nearly sine wave by possessing a waveform generating circuit, which generates a nearly sine wave based on an input signal between an oscillating circuit and an electric-mechanical energy converting element, in a drive circuit equipped with a bridge circuit for switching DC single power. CONSTITUTION:In a driving circuit, which is arranged so as to positively reverse a plurality of surface wave motors by a plurality of H bridge circuits, fixed frequency signals generated from an oscillator 72 are inputted into an X wave voltage generating circuit 73, an X wave voltage generating circuit 74, an Y wave voltage generating circuit 75, and a Y wave voltage generating circuit 76. And, they are converted, respectively, into the AC voltage of sine waves, and are inputted into an analog multiplexer 77, and as its control input, any one is applied, out of motor control signals A, B, C, D, E, F, G, and H, so as to get signals a1, b1-h1, a2, and b2-h2 to control the transistor of a bridge circuit at the output terminals, and sine wave signals are applied to the surface wave motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a surface wave motor, and more particularly to a drive circuit for a surface wave motor in which a plurality of H-shaped bridge circuits are used to control forward and reverse rotations of a plurality of surface wave motors. It is a thing.

[0002]

2. Description of the Related Art As a driving circuit for a surface wave motor, that is, an ultrasonic motor, a single DC power source is conventionally used as a push-pull type bridge circuit as disclosed in JP-A-59-96882. A circuit that amplifies and generates an AC signal to be applied to a motor is known. With such a circuit,
Since the bridge circuit is used for the power amplification circuit, the power amplifier circuit has a simple structure, and the circuit can be made small and inexpensive.

[0003]

The signal applied to the surface wave motor is preferably a substantially sine wave in order to improve efficiency and reduce abnormal noise. However, the above-mentioned conventional JP-A-59-968
In the device disclosed in Japanese Patent Publication No. 82, the H-type bridge circuit is switched by a digital element, so that the waveform of the AC signal becomes a square wave. Therefore, there is a problem that the efficiency of the surface wave motor is reduced.

An object of the present invention is to eliminate the above-mentioned problems in the conventional drive circuit for a surface wave motor and to make the AC signal waveform applied to the surface wave motor substantially sinusoidal. To provide.

[0005]

SUMMARY OF THE INVENTION The present invention provides a driven member which is brought into contact with the surface of a vibrating body by applying an AC signal to an electro-mechanical energy conversion element to generate a surface wave on the surface of the vibrating body. In a drive circuit of a surface wave motor to be driven, an oscillating circuit that regulates the frequency of the AC signal, and a non-linear element that is provided between the oscillating circuit and the electric-mechanical energy conversion element and push-pulls a DC single power source. A bridge circuit that amplifies and outputs an input signal by being configured, is provided between the oscillator circuit and the electro-mechanical energy conversion element, and generates a substantially sine wave based on the input signal. And a waveform generating circuit.

[0006]

[Operation] An AC signal having a substantially sinusoidal waveform generated by the waveform generation circuit is applied to the surface wave motor.

[0007]

The present invention will be described below with reference to the illustrated embodiments. First, before describing the present invention, an electric circuit for driving a plurality of motors using a plurality of H-type bridge circuits, which is a premise of the present invention, will be described.

FIG. 1 is an electric circuit diagram of a motor drive circuit when three electromagnetic drive motors are used. In this motor drive circuit 30, three motors M1, M2, M3 are used, and PNP transistors Qa, Qc and NPN transistors Qb, Qd for driving the motor M1 are also used.
PNP transistors Qc and Q for driving the motor M2
Further, e and NPN transistors Qd and Qf are used to drive PNP transistors Qe, Qg and N for driving the motor M3.
The PN transistors Qf and Qh respectively form a bridge circuit. That is, the three motors M1, M2, M
3 is continued, and the transistors Qc and Qd are shared by the two adjacent motors M1 and M2.
Transistors Qe and Qf are shared for 2 and M3. Then, in parallel with the transistors Qb, Qd, Qf, Qh, the diodes Db, Dd, D for transistor protection are provided.
f and Dh are connected.

As described above, the above-described circuit has a configuration in which two transistors (one PNP transistor and one NPN transistor) and one diode are shared between two adjacent motors, and therefore the number of motors is further increased. If the number is increased, only two transistors and one diode are increased per motor. When the motor drive circuit 30 is configured as described above, the number of motors (M), the number of PNP transistors (PNP), N
The number of PN transistors (NPN), the number of diodes (D), and the total number of elements are shown in Table I below.

Table I Next, a case where the motor drive circuit is applied to a motor drive circuit of an electric single-lens reflex camera will be described. For example, the motor M1 is a focus lens drive motor, the motor M2 is a mirror up / down drive motor, and the motor M3. Is a film winding / rewinding drive motor, the respective motors M1, M2, M3 are arranged as shown in FIG. In FIG. 2, reference numeral 4 denotes a camera body, 5
Is a taking lens barrel, and 6 is a release button. In the vicinity of the release button 6, a first stroke (half-pressed state) detection switch SW1 and a second stroke (released state) detection switch SW2 of the button are attached. The distance measurement is started by turning on the first stroke detection switch SW1, and the second stroke detection switch SW2.
Turn on to start mirroring up.

The structure of the focus lens driving motor M1 and its peripheral portion in the camera body 4 is shown in FIG. The subject image that has passed through the focus lens 8 in the photographic lens barrel 5 passes through the central light projecting portion of the main mirror 9 and is reflected by the sub mirror 10 to be measured by the distance measuring element 1.
The focus lens driving motor M1 rotates normally or reversely according to the distance measurement calculation value based on the output of the distance measuring element 11, and meshes with the gear 12 provided on the output shaft of the motor M1. Lens drive gear (not shown)
The focus lens 8 in the lens barrel 5 is driven by rotating the.

The mirror drive motor M2 and its peripheral portion are constructed as shown in FIG. The rotating shaft 9a of the main mirror 9 is integrally fixed to the output shaft of the motor M2, and the main mirror 9 is driven by the rotation of the motor M2. The main mirror 9 moves up when the motor M2 rotates in the forward direction, and moves down when the motor M2 rotates in the reverse direction. Further, the ascending stationary position 9A shown by the broken line in FIG. 4 and the descending stationary position shown by the solid line of the main mirror 9 are detected by the mirror position detecting switches 13 and 14, respectively.

Further, the film winding / rewinding drive motor M3 and its peripheral portion are constructed as shown in FIG. In FIG. 5, the shaft of the sun gear 16 of the planetary gear mechanism 15 is fixed to the output shaft of the motor M3.
When 3 rotates normally, the sun gear 16 rotates in the direction of the arrow indicated by the solid line. Therefore, the planetary gear 18 meshingly connected to the sun gear 16 by the connecting member 17 is
It rotates counterclockwise around and meshes with the gear 19 integrally with the sprocket 20. After that, the normal rotation of the sun gear 16 is sequentially transmitted to the planetary gear 18, the gear 19, the gear 21, and the gear 22, and the spool 23 integrally fixed to the gear 22 is transmitted.
Rotates the film 7 in the direction of the arrow indicated by the solid line. A protrusion 20a is integrally provided on the lower end of the sprocket 20, and a switch 24 for detecting one rotation of the sprocket 20 is provided at a position where the protrusion 20a can be detected.

Further, in FIG. 5, when the motor M3 rotates in the reverse direction, the sun gear 16 rotates in the direction of the arrow indicated by the broken line. Therefore, the planetary gear 18 rotates clockwise around the sun gear 16 and meshes with the gear 25. After that, the reverse rotation of the sun gear 16 is changed to the planetary gear 18 → the gear 25 → the gear 26 →
The film is sequentially transmitted to the gear 27, which is sequentially transmitted to the gear 27 which rotates in the direction of the arrow indicated by the broken line, and the winding shaft 28 which is integrally fixed to the gear 27 which rotates in the direction of the arrow indicated by the dashed line rotates in the same direction. The winding rotation for storing 7 in the cartridge 29 is performed.

FIG. 6 shows the motor drive circuit 3 shown in FIG.
FIG. 7 is an electric circuit diagram of a decoder for controlling 0 transistors Qa to Qh. This decoder 31 is an inverter I
N1 and IN2, OR gates OR1 to OR4 and NOR gates NOR1 and NOR2, each output of the decoder 31 when any one of the nine positive motor control signals A to I is applied as a decoder input. The signals NOTa to h of the terminals are output in response to the above inputs as shown in the truth table of Table II below. The signals NOTa to h obtained at the output terminals of the decoder 31 are the transistors Qa to Qh of the motor drive circuit 30 shown in FIG.
Applied to the base of each.

Table II As is apparent from Table II above, when the signal A is applied to the decoder 31, for example, the output signal of the decoder 31 is the output NOTa of the inverter IN1 and the OR gate O.
The outputs b, f, and h of R1, OR3, and OR4 are the ground potential G.
It becomes "L" level equal to ND, and NOR gate NOR1
, NOR2 outputs NOTc, NOTe, OR gate OR2
Output d and the output NOTg of the inverter IN2 become "H" level equal to the power supply voltage VDD. As a result, only the transistors Qa and Qd of the motor drive circuit 30 are turned on and the other transistors are turned off.
1 rotates forward. Further, when the signal B is applied, the output signal of the decoder 31 is inverted from the outputs NOTa and b to the “H” level, and the output NOTc of the decoder 31 is higher than that when the signal A is applied. , D are inverted to the "L" level, and in this case, only the transistors Qb and Qc of the motor drive circuit 30 are turned on, the other transistors are turned off, and the motor M1 is reversed. When the signal C is further applied, the output signal of the decoder 31 is the output NOTa,
Since b, NOTc, and d are all at "H" level, in this case, only the transistors Qb and Qd are turned on, the other transistors are turned off, the both ends of the motor M1 are at the ground potential, and the brake is applied to the motor M1. The motor stops rotating. At this time, the diodes Db and Dd prevent an excessive reverse current from flowing through the transistors Qb and Qd.

Similarly, when the signal D is applied, the transistors Qc and Qf are turned on, the motor M2 is normally rotated, and the signal E
When the signal F is applied, the transistors Qd and Qe turn on and the motor M2 reverses. When the signal F is applied, the transistors Qd and Qf turn on and the motor M2 is braked to stop the rotation of the motor.

Similarly, when the signal G is applied, the transistors Qe and Qh are turned on and the motor M3 is normally rotated. When the signal H is applied, the transistors Qf and Qg are turned on and the motor M3 is reversed, and the signal I is changed. When applied, the transistors Qf and Qh are turned on and the motor M3 is braked and the motor stops rotating.

The motor control signal A is sent to the decoder 31.
~ I is not applied and all decoder inputs are "L"
In the case of the level, the state is the (J) state shown in Table II above. Therefore, all the transistors Qa to Qh of the motor drive circuit 30 are turned off and the motors M1 to M3 are stopped.

FIG. 7 shows an electric circuit for performing sequence control so that at least two motors among the motors M1, M2 and M3 of the motor drive circuit 30 do not operate. The distance measuring block 41 is a circuit that detects whether the subject image is in focus or out of focus (front focus or rear focus) and sends the code signals FA and FB to the sequence control block 43. As shown in Table III below, the code signals FA and FB have "H" and "L" levels determined according to the focus detection state.
When the code signals FA and FB are “L” and “L”, focus is achieved,
If it is "L" or "H", the front pin is determined, if it is "H" or "L", the rear pin is determined, and if it is "H" or "H", the undetectable state is determined.

Table III Further, the exposure control block 42 controls the exposure of the diaphragm and the shutter by the exposure start signal ES from the sequence control block 43, and transmits the exposure end signal ED to the sequence control block 43 at the end of the exposure. The motor drive block 44 is composed of the motor drive circuit 30 shown in FIG. 1 and the transistor drive decoder 31 shown in FIG. 6, and is supplied with the motor control signals A to I from the sequence control block 43. The motors M1, M2 and M3 are drive-controlled as described above. Further, the sequence control block 43 outputs signals R1 and R indicating the ON / OFF states of the first stroke detection switch SW1 and the second stroke detection switch SW2 of the release button 3.
2 to read the mirror position detection switches 13 and 14
It is possible to read the on / off state of the sprocket 20 with the signals MU and MD, and to read the on / off state of the one-rotation detection switch 24 of the sprocket 20 with the signal SP.

It should be noted that the detection of the completion of the winding of the final frame of the film 7 and the completion of the rewinding of the film after the shooting of all the frames is completed,
The one-turn detection switch 24 is used. That is, for example, as shown in FIG. 8, the detection circuit 46 for the completion of the winding and the completion of the rewinding of the final frame.
The signal of a constant frequency generated by the oscillator 47 is frequency-divided by the 1/2 frequency divider 48 and the inverter 49
Is inverted to be a first input of the AND gate 50, and the output signal of the oscillator 47 having a constant frequency is directly used as a second input of the AND gate 50. Further, the output of the oscillator 47 and the output of the 1/2 frequency divider 48 are the AND gate 5
1 through the RS flip-flop circuit (hereinafter, RS
-FF) is input to the reset input terminal R of 52,
The detection signal SP of the one-rotation detection switch 24 of the sprocket 20 is input to the set input terminal S of the RS-FF 52. The output signal from the inverting output terminal NOTQ of the RS-FF 52 is the third input of the AND gate 50.

This all-frame winding completion / rewinding completion detection circuit 46
, When the output of the AND gate 51 is input to the reset input terminal R of the RS-FF 52 and the detection signal SP is input to the set input terminal S as the signals shown in FIG.
The output signal from the output terminal NOTQ of the RS-FF52 is shown in FIG.
As shown in. As is apparent from FIG. 9, when the winding of the last frame is completed or the rewinding is completed and the rotation of the sprocket 20 is stopped, the signal SP is not generated either. Therefore, after this time, the level of the output terminal NOTQ, that is, The third input level of the AND gate 50 becomes "H". Then, after this, the first and second of the AND gate 50
When the input levels of 2 and 5 simultaneously become "H", the AND gate 50 generates the sprocket stop signal T of "H" level for a certain time (1/2 cycle of the oscillation frequency signal of the oscillator 47).

The sequence control operation of the sequence control block 43 shown in FIG. 7 will be described with reference to the flow chart shown in FIG. 10. When the power is turned on and the operation starts, first, the state of the signal R1 is detected and the release switch 6 is released. First stroke detection switch SW1 (Fig. 2
(See) is turned on. When the signal R1 is at "L" level due to the switch SW1 being turned on, the distance measurement is started. Focusing, non-focusing (front focus or rear focus), and undetectable states are detected from the states of the code signals FA and FB. In the case of front focus or rear focus, the focus lens is driven. If the motor M1 is controlled to rotate normally or reversely, and it is determined that the motor is in focus or cannot be detected, the motor M1 is braked and the rotation of the motor M1 is stopped.

After that, the state of the signal R2 is detected to detect the second stroke detection switch SW2 of the release switch 6.
It is determined whether (see FIG. 2) is turned on.
When the signal R2 is at the "L" level by turning on the switch SW2, the forward rotation control of the mirror up / down drive motor M2 is performed, and the mirror up is started. When the mirror-up detection switch 13 is turned on to bring the signal MU to the "L" level and the mirror-up is completed, the motor M2 is braked and the rotation of the motor M2 is stopped. after this,
When the exposure is started and the exposure is completed, the motor M2 is rotated in the reverse direction and the mirror down is started.

Then, the mirror down detection switch 14
Is turned on, the signal MD becomes "L" level, and when the mirror down is completed, the motor M2 is braked again and the rotation of the motor M2 is stopped. Thereafter, the film winding / rewinding drive motor M3 rotates in the forward direction to start film winding. When the sprocket 20 makes one rotation and the film is wound up by one frame, the signal SP detects this and the motor M3 is braked to stop the rotation of the motor M3 and return to the start state and the above-mentioned operation is performed. Is repeated. When the last frame of the film 7 is wound up and the rotation of the sprocket 20 is stopped, the detection signal SP is not generated and the sprocket stop signal T is generated. At this time, the winding / rewinding drive motor M3 is driven. After the brake is applied to stop the rotation, the motor M3 is started to rotate in the reverse direction to rewind the film. When the film rewind is complete,
Similarly, when the rotation of the sprocket 20 is stopped, a sprocket stop signal T is issued, the motor M3 is braked again, the rotation of the motor M3 is stopped, and the state returns to the start state.

Needless to say, the camera can be configured so that the plurality of motors do not operate within the same time regardless of the operation shown in the flow chart of FIG.

Next, a drive circuit of a surface wave motor (ultrasonic motor) showing an embodiment of the present invention will be described. This embodiment is applied to the motor drive circuit of the camera as described above. The surface wave motor is a motor that has been developed in recent years.Since it rotates at a low torque with a large torque compared to conventional motors, a speed reducer is not required and the mechanism is simple, making it suitable as an actuator for a camera autofocus mechanism. There is. Therefore, before describing the present embodiment, first, the driving principle of this surface wave motor will be described with reference to FIGS. 11 to 14 (the following description of the driving principle will be made by Nikkei Mechanical 1983.
Quoted from No. 2.28).

As shown in FIG. 11, the surface acoustic wave motor 60 has a ring-shaped driven member (rotor) 61, a ring-shaped elastic body 62 which is a vibrating body, and two piezoelectric elements which are electric-mechanical energy converting elements. It is composed of elements 63 and 64. The electro-mechanical energy conversion element is configured by stacking a plurality of piezoelectric elements 63a and 64a arranged in a ring shape, and the plurality of piezoelectric elements 63a form a semi-ring piezoelectric element 63, and the rest. The semi-ring-shaped piezoelectric element 64 is formed by the plurality of piezoelectric elements 64a. An equivalent circuit of the surface acoustic wave motor 60 is such that the two piezoelectric elements 63 and 64 are connected to two oscillators P1 and
This can be represented by showing P2.

When a signal voltage is applied to the piezoelectric elements 63 and 64, the piezoelectric elements 63 and 64 oscillate and bending vibration is generated in the elastic body 62. Therefore, the elastic body 62 generated by this bending vibration is generated.
The driven member 61 is adapted to rotate using a surface traveling wave that draws an elliptical locus on the surface of the drive source. This will be further described with reference to FIG. 13 in which the contact portion between the elastic body 62 and the driven member 61 is enlarged.
When a signal voltage Vsin ωt shown in FIG. 4 is applied and a signal voltage Vcos ωt is applied to the piezoelectric element 64 to oscillate the piezoelectric elements 63 and 64, bending vibration occurs in the elastic body 62, and the elastic body 62 Vibration propagates in the direction indicated by arrow n along the surface of. At this time, paying attention to one point A0 on the surface of the elastic body 62, the point A0 draws an elliptical locus with the major axis 2w and the minor axis 2u. Therefore, the point A0 has a velocity of v = 2πfu in the negative direction of the x-axis (where f is the vibration frequency of the piezoelectric elements 63 and 64).

As a result, the driven member 61 is driven by the frictional force with the elastic body 62 at the speed v in the direction indicated by the arrow N, which is opposite to the traveling of the wave of the vibration. The driven member 61 is driven in the direction indicated by the arrow N in the surface wave motor 6.
Assuming that the rotation is 0, the signal voltage of V sin ωt is applied to the piezoelectric element 63 as it is, and
, A signal voltage of −Vcos ωt shown in FIG. 14 is applied to oscillate both piezoelectric elements 63 and 64. Then, this time, the vibration along the surface of the elastic body 62 propagates in the direction opposite to the above case, and as a result, the driven member 61 moves at the speed v in the direction opposite to the arrow N. When driven, this surface wave motor 60 is rotated in the reverse direction. FIG. 15 shows an embodiment of a motor drive circuit configured by using three surface wave motors 60 that operate on the above-described drive principle, as in the case of FIG. In the motor drive circuit 70 shown in FIG.
Motor MI, oscillators P21, P22 by oscillators P11, P12
Motor MII and oscillators P31 and P32 to motor MII
Each I is configured. Motor MI, MII, MII
I, for example, is used for focus lens driving, mirror up / down driving, and film winding / rewinding driving, respectively, as in the camera. For each of the six oscillators P11 to P32 in total, a bridge circuit is formed by two PNP transistors and two NPN transistors. Since the two adjacent oscillators P11 and P21, P21 and P31, P12 and P22, and P22 and P32 are directly connected to each other, the transistors provided between them are adjacent to each other. It is designed to be used to drive two oscillators.

That is, the transistors Qc1 and Qd1 are the oscillator P.
11 and P21 are used to drive the transistors Qe1 and Qf1. The transistors Qe1 and Qf1 are used to drive the oscillators P21 and P31.
2, Qd2 are used to drive the oscillators P12 and P22, and the transistors Qe2 and Qf2 are used to drive the oscillators P22 and P32. Therefore, the motor drive circuit 70 is configured using a total of 16 transistors for 6 vibrators.

Further, the surface wave motor 60 (MI, MII, M
In III), the torque is extremely large, and the motor stops immediately when the oscillation of the oscillator stops. Therefore, the diode for transistor protection required in the case of the electromagnetic drive motor is not necessary.

An electric circuit for supplying signals NOTa1 to h1 and NOTa2 to h2 to the bases of the motor control transistors Qa1 to Qh1 and Qa2 to Qh2 of the motor drive circuit 70 shown in FIG. 15 is constructed as shown in FIG. It That is,
The circuit shown in FIG. 16 forms a waveform generating circuit according to the present invention, and outputs a constant frequency signal generated from an oscillator 72, which is an oscillating circuit, to an X waveform voltage generating circuit 73, a NOTX waveform voltage generating circuit 74, and a Y waveform voltage. Generator circuit 75 and N
The OTY waveform voltage generation circuit 76 converts the AC voltages X, NOTX, Y, and NOTY shown in FIG. 17, respectively. The AC voltages X, NOTX, Y, and NOTY are respectively X = (VDD / 2) (1 + sin ωt) NOTX =-(VDD / 2) (1 + sin ωt) Y = (VDD / 2) (1 + cos ωt) NOTY =- It is expressed by the equation (VDD / 2) (1 + cos ωt). This AC voltage X, NOTX, Y,
NOTY is input to the analog multiplexer 77. The analog multiplexer 77 has one of the motor control signals A, B, D, E, G, and H as its control input.
When the two are applied, the signals NOTa1 to h1 at the output terminals,
As NOTa2 to h2, the values shown in the truth table of Table IV below are output.

Table IV The electric circuit of the analog multiplexer 77 is shown in FIG.
As shown in FIG. 5, it is composed of OR gates ORa to ORk and analog switches S1 to S44. In FIG. 18, when the motor control signal A is input, the outputs of the OR gates ORa, ORb, ORe, and ORg become "H" level by the signal A, so that the analog switches S3 and S3.
4, S7, S8, S11, S12, S15, S16, S17, S1
The gates of 8, S23, S24, S29, S33, S39, and S40 are set to "H" level to turn on these analog switches, and the output of the analog multiplexer 77 is NOTa.
1 = b1 = X, NOTc1 = d1 = NOTX, NOTe1 = N
OTg1 = VDD ("H"), f1 = h1 = GND
("L"), NOTa2 = b2 = Y, NOTc2 = d2 = N
OTY, NOTe2 = NOTg2 = VDD ("H"), f2 = h2
= GND (“L”). That is, at this time, FIG.
, The transistors Qa1 and Qb1 are controlled by the AC voltage X, the transistors Qc1 and Qd1 are controlled by the AC voltage NOTX, the transistors Qa2 and Qb2 are controlled by the AC voltage Y, and the transistors Qc2 and Qd2 are controlled by the AC voltage NOTY. As a result, the surface wave motor MI composed of the oscillators P11 and P12 rotates in the normal direction.

Similarly, when the motor control signal B is input, the output of the analog multiplexer 77 becomes as shown in Table IV above. Therefore, from the normal rotation state of the motor MI,
Transistors Qa2 and Qb2 are controlled by AC voltage NOTY,
The transistors Qc2 and Qd2 are controlled by the AC voltage Y, and the motor MI is reversed.

When the motor control signal D is input, the transistors Qc1 and Qd1 are controlled by the AC voltage X, the transistors Qe1 and Qf1 are controlled by the AC voltage NOTX, and the transistors Qc2 and Qd2 are controlled by the AC voltage Y. Controlled,
Since the transistors Qe2 and Qf2 are controlled by the alternating voltage NOTY, the surface wave motor MII composed of the oscillators P21 and P22 rotates in the normal direction. From this state, when the motor control signal E switches the transistors Qc2 and Qd2 to the AC voltage NOTY and the transistors Qe2 and Qf2 to the AC voltage Y, the motor MII rotates in the reverse direction. Further, by the motor control signals G and H, the multiplexer output shown in the above Table IV is obtained in the same manner.
The surface wave motor MIII is rotated normally and reversely.

When any of the motor control signals is not applied (J), all the transistors are turned off, so that all of the oscillators P11 to P32 stop oscillating and the motors MI, MII, MIII are stopped. Everything goes to a standstill. The sequence control of the camera using the motor drive circuit 70 can be carried out in substantially the same manner as the operation of the flow chart shown in FIG. 10 with the same circuit configuration as the circuit shown in FIG. In order to control the motors MI, MII, MIII of 70, individual brake control of these motors is unnecessary, and common brake control can be performed by the off mode (J) of all motor control transistors. Only about.

Further, in the drive circuit using the electromagnetic drive motor shown in FIGS. 1 to 10, in order to use the transistor more efficiently, for example, a motor drive circuit 80 shown in FIG. 19 is used. Can be configured. This Figure 1
The motor drive circuit 80 shown in FIG. 9 has three motors M1 and M2.
, M3, six transistors Qa to Qf and three diodes Db, Dd, Df are used, and the transistors Qg, Qh and the diode Dh used in the motor drive circuit 30 shown in FIG. 1 are used. Is omitted.

That is, in the motor drive circuit 80, the transistors Qg and Qh and the diode Dh in the motor drive circuit 30 are omitted, and the transistor Qg
One end of the motor M3, which was connected to the connection point of g and Qh, is connected to the connection point of the transistors Qa and Qb, and a changeover switch 81 is further provided at the connection point of the transistors Qe and Qf. Contacts 81a and 81b are provided at the other ends of M3, respectively. Therefore, by connecting the changeover switch 81 with the contacts 81a and 81b, the motor M2 or M3 is connected to the transistors Qe and Qf. .

The changeover switch 81 is, for example, as shown in FIG.
As shown in FIG. 7, the contact piece of the changeover switch 81 is connected to the contact 81a in association with the release operation of the release member 82, and the contact piece of the switch 81 is connected to the contact 81b in association with the release opening operation of the release member 82. To connect.

Transistor Q of the motor drive circuit 80
The decoder for controlling a to Qf is configured as shown in FIG. That is, the decoder 83 comprises OR gates OR5 to OR7 and NOR gates NOR3 to NOR5. Therefore, when one of the motor control signals A to I is added at the "H" level as an input to the decoder 83, the decoder 83 sends a signal NOT to the bases of the transistors Qa to Qf of the motor drive circuit 80.
a to f are applied respectively. The signals NOTa to f change according to the motor control signals A to I as shown in the truth table of Table V below.

Table V As is clear from comparison between Table V and Table II, regarding the motor control of the motor drive circuit 80, the motor M1
The motor control of the motor drive circuit 30 is the same as that of the motor drive circuit 30. However, when the motor M2 is controlled, the motor control of the motor drive circuit 30 is performed with the changeover switch 81 connected to the contact 81a. Transistor control is performed by the same decoder output as in the above case. When controlling the motor M3, the changeover switch 81 is connected to the contact 81b, and the transistors Qa and Qb are connected.
, M3 by a bridge circuit composed of Qe, Qf
Control.

That is, the motors M3 are normally rotated by turning on the transistors Qa and Qf by the signals NOTa and f, and the transistor Qb by the signals b and NOTe.
And Qe are turned on to reverse the motor M3, and the signals b and f are used to turn on the transistors Qb and Qf.
By turning on and, the brake is applied to the motor M3 and the motor M3 is stopped. In the state (J) in which none of the signals A to I is input as the decoder input, all the transistors are off and all the motors M1 to M3 are in the stopped state, as in the circuit shown in FIG. is there.

In the above motor drive circuit, the case where three motors are used has been described, but it goes without saying that two or more motors can be driven and controlled by the same circuit configuration. If necessary, at least two adjacent motors among the three or more motors may have the above-described configuration of the present invention, and the other motors may have the transistor connection configuration of the conventional motor drive circuit. It goes without saying that it is okay.

[0046]

As described above, according to the present invention, even though the power amplifier is constituted by the push-pull type bridge circuit, a substantially sinusoidal signal can be applied to the surface wave motor, so that the efficiency is improved. Up and reduction of abnormal noise can be realized, and problems of this type and conventional motor drive circuit can be solved.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of each motor drive circuit which is a premise of the present invention.

FIG. 2 is a schematic front view showing an arrangement example of motors in the camera.

FIG. 3 is a schematic side view showing an application example of a focus lens driving motor.

FIG. 4 is a schematic perspective view showing an application example of a mirror up / down drive motor.

FIG. 5 is a schematic perspective view showing an application example of a film winding / rewinding drive motor.

6 is an electric circuit diagram of a decoder for obtaining a transistor control signal of the motor drive circuit shown in FIG.

7 is a block diagram of an electric circuit for sequence control of a camera having the motor drive circuit shown in FIG.

FIG. 8 is an electric circuit diagram for detecting rotation stop of a sprocket when rewinding is completed.

9 is a time chart for explaining the circuit operation of FIG.

10 is a flowchart illustrating the operation of the sequence control block shown in FIG.

FIG. 11 is an exploded perspective view showing an example of a surface acoustic wave motor.

12 is a diagram showing an equivalent circuit of the surface acoustic wave motor shown in FIG.

13 is an enlarged perspective view illustrating the operating principle of the surface acoustic wave motor shown in FIG.

FIG. 14 is a waveform diagram of an electric signal applied to the oscillator of the surface acoustic wave motor.

FIG. 15 is an electric circuit diagram of a drive circuit for a surface acoustic wave motor showing an embodiment of the present invention.

16 is a block diagram of an electric circuit for supplying a transistor control signal to the motor drive circuit shown in FIG.

FIG. 17 is a waveform diagram of an electric signal obtained in the electric circuit shown in FIG.

18 is an electric circuit diagram of the analog multiplexer in FIG.

FIG. 19 is an electric circuit diagram showing another example of each motor drive circuit which is a premise of the present invention.

20 is a schematic side view showing an arrangement configuration example of the changeover switch in FIG.

21 is an electric circuit diagram of a decoder for obtaining a transistor control signal of the motor drive circuit shown in FIG.

[Explanation of symbols]

61 .............. Driven member 62 .............. Vibrator 63, 64 ..... Electric-mechanical energy conversion element (piezoelectric element) 72 ........ Oscillation circuit (oscillator) ) 73-76 ... Waveform generation circuit (waveform voltage generation circuit) MI, MII, MIII ... Surface wave motor Qa1 to Qh1, Qa2 to Qh2 ... Transistor (bridge circuit)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03B 13/36 17/00 J 19/12 7513-2K 7316-2K G03B 3/00 A

Claims (1)

[Claims] 1. A drive circuit for a surface wave motor for applying an AC signal to an electromechanical energy conversion element to generate a surface wave on the surface of a vibrating body and driving a driven member brought into contact with the surface of the vibrating body. In the above, an input is made by an oscillation circuit that regulates the frequency of the AC signal, and a nonlinear element that is provided between the oscillation circuit and the electro-mechanical energy conversion element and that push-pulls a DC single power source. A bridge circuit that amplifies and outputs a signal; and a waveform generation circuit that is provided between the oscillation circuit and the electro-mechanical energy conversion element and that generates a substantially sine wave based on the input signal. A drive circuit for a surface wave motor characterized by the above.