JP2005168244A - Control device for vibration-type drive unit, device using this control device, optical apparatus using this control device, and control method and control program for the vibration-type drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vibration-type drive unit, having with a simple constitution and high working precision. <P>SOLUTION: This control device for a vibration type drive unit for relatively driving the vibration body, comprising the vibration body which is energized by an electric energy-mechanical energy conversion element applied with a frequency signal, and a contact body contacting with the vibration body, is provided with: a vibration detection device for detecting the vibration states of the vibration body; a time-difference detection device for detecting a time difference as a delay time of an output signal from the vibration detection device relative to the frequency signal; a phase difference detection device for detecting the phase difference between the frequency signal and the output signal; a drive control device for performing a first drive control which controls driving of the vibration type drive unit, based on the time difference and a second drive control which controls driving of the vibration type drive unit, based on the phase difference; and a switching control device for control and switching for the first drive control and the second drive control. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a device using a vibration wave motor (the same applies to an ultrasonic motor) and a phase difference between a signal phase for mainly detecting a vibration state of the vibration wave motor and an application phase for applying an AC electric field to the ultrasonic motor. In addition, the present invention relates to a vibration wave motor control method for controlling the rotational speed, power consumption, and the like of the vibration wave motor by detecting the time difference and switching to one of the detection methods as necessary.

  Conventionally, a vibration wave motor is set so that an alternating electric field applied to a vibrating body rotates in two application phases (hereinafter referred to as A phase and B phase, respectively) having a certain phase difference. The phase difference between the A phase and the B phase is ± 90 degrees, and the rotation direction is determined by this positive / negative. The rotation speed is generally controlled to a desired speed by changing the voltage applied to the motor and the frequency of the A phase and the B phase.

  The vibration wave motor is usually coupled to a mechanical rotating body (or a moving body), and generally performs speed feedback control in order to stabilize the rotational speed of the rotating body. FIG. 3 shows the relationship between the frequency and the rotational speed and phase of the vibration wave motor. From this figure, it can be seen that the rotational speed of the vibration wave motor can be changed by changing the frequency applied to the motor. As shown in the figure, when the frequency applied to the motor is high, the rotational speed is slow, and by decreasing the frequency, the rotational speed gradually increases, and when passing through a certain point, it tends to be slow again. This rotation speed switching point is called the resonance frequency of the vibration wave motor.

  As shown in the figure, the characteristic of the vibration wave motor is that the region where the frequency is higher than the resonance frequency has a longer rotation speed with respect to the frequency, and the frequency falls below the resonance frequency. When performing control, it is common to use a frequency band higher than the resonance frequency.

  In addition, when the resonance frequency is exceeded, the relationship between the control frequency and the rotational speed is reversed, and it is necessary to perform control so as not to exceed the resonance frequency. Further, it can be seen from FIG. 3 that the control near the resonance has a large change in the rotational speed with respect to the applied frequency and it is difficult to perform the speed control.

  Therefore, a sensor phase (hereinafter referred to as S phase) for detecting the vibration state of the vibration body is provided in a part of the vibration body, and the phase difference between the S phase and the A phase or the S phase and the B phase is detected to detect the resonance state of the vibration body. Currently, a method for performing control by detecting the above has been put into practical use (see, for example, Patent Document 1). From FIG. 3, the phase (or time difference) relationship between the A phase or the B phase and the S phase tends to decrease as the resonance frequency is approached.

  Therefore, PLE2 and PLE1 set boundaries for determining that the phase has become smaller, and it is necessary to change the frequency control method when the boundaries are exceeded.

As a method for detecting this phase, there is a method in which a sine wave is converted into a square wave using a comparator, which is an electrical element, and the time from the rise of the B phase to the rise of the S phase is measured as shown in FIG. The phase difference (or time value) measured here is compared with the preset PLE1 or PLE2 value, and if it is less than that value or out of range, the A phase and B phase frequencies are set to a lower side. In addition, there is a control that prevents the vibrating body from exceeding the resonance frequency by taking measures such as resetting the motor to a higher frequency side than the present time and reducing the rotational speed of the motor.
JP 05-137360 A

  In the description of FIGS. 2 and 3 of the prior art, it is described that “the phase difference between the applied phase (A or B phase) and the S phase of the vibration wave motor is detected”, but in reality, a time difference may be used instead of a phase difference. . This is a very narrow frequency range of 29 KHz to 31 KHz due to the relationship between the rotation speed and frequency of the vibration wave motor of FIG. That is, the time difference between the S phase and the B phase can be approximated as a phase difference. To explain this further, from FIG. 2, when the period of the B phase is T, the frequency of the B phase is 1 / T (of course, the frequency of the S phase is also 1 / T).

  Further, if the phase is a signal delayed by T / 4 with respect to the B phase, the phase is + 90 ° because the phase is 360 ° / 4. As an arithmetic expression at this time, the phase φ = t / T / 360. When the numerical values are actually applied, if the frequency f of the A phase or the B phase is 29 KHz to 31 KHz, the cycle T = 34.48 μsec to 32.26 μsec from T = 1 / f. If the phase difference is + 90 °, the time difference is t = 8.62 μsec to 8.07 μsec. Since the difference is as extremely small as 0.55 μsec, there is no problem even if the phase detection is approximated by the time difference.

  The reason why the time difference detection method is adopted is that it can be detected at low cost. In order to electrically perform the original phase detection described above, division is necessary, which complicates the circuit configuration. Therefore, in reality, it is desirable to detect by calculation using a microcomputer. However, if calculation is performed, a divider is required in the microcomputer (hereinafter referred to as microcomputer) as shown in the above formula, and an expensive microcomputer is used. Must be used.

  In addition, when a microcomputer without a divider is used, the processing takes time, and as a result, the performance of the microcomputer is lowered, and there is a problem that stable speed control cannot be obtained in the vibration wave motor.

  In addition, as the cost reduction and speed increase in all devices in the future, it is naturally necessary to increase the rotation speed of the vibration wave motor. At that time, there is a possibility that the vibration wave motor needs to be controlled near the resonance frequency. For this purpose, accurate and fine phase control is necessary, and it is considered that the detection with a time difference is insufficient in accuracy. Naturally, an easy cost increase must be avoided.

  In order to solve the above problems, a first configuration of the control device of the vibration type driving device according to the present invention includes a vibrating body in which vibration is excited by an electro-mechanical energy conversion element to which a frequency signal is applied, and the vibrating body. A vibration-type drive device control device for relatively driving the vibration body and the contact body, the vibration detection means for detecting the vibration state of the vibration body, and the vibration detection means for the frequency signal A time difference detecting means for detecting a time difference which is a delay time of the output signal from the output signal, a phase difference detecting means for detecting a phase difference between the frequency signal and the output signal, and a first control for controlling the driving of the vibration type driving device based on the time difference. Drive control means for performing drive control of 1 and second drive control for controlling the drive of the vibration type drive device based on the phase difference; and switching control means for performing switching control of the first and second drive controls. Features having To.

  The switching control means may be configured to perform switching control according to the time difference. The switching control means may be configured to cause the drive control means to perform the first drive control when the time difference is smaller than the predetermined time, and to cause the drive control means to perform the second drive control when the time difference is greater than the predetermined time. .

  It is preferable to provide speed detecting means for detecting the driving speed of the vibration type driving apparatus or a driven member driven by the vibration type driving apparatus, and to make the switching control means perform switching control according to the driving speed.

  The switching control means causes the drive control means to perform the first drive control when the drive speed is lower than the predetermined speed, and causes the drive control means to perform the second drive control when the drive speed is higher than the predetermined speed. It is good to let them.

  The switching control means may be configured to cause the drive control means to perform the first drive control when starting the vibration type driving device.

  An apparatus having a control device, a vibration type driving device, and a driven member driven by the vibration type driving device.

  An optical apparatus having a control device, a vibration type driving device, and an optical member driven by the vibration type driving device.

  The first configuration of the control method of the vibration type driving device of the present invention includes a vibrating body in which vibration is excited by an electro-mechanical energy conversion element to which a frequency signal is applied, and a contact body in contact with the vibrating body. A method for controlling a vibration type driving device that relatively drives a vibrating body and a contact body, the step of detecting a vibration state of the vibrating body, and a time difference that is a delay time of an output signal from a vibration detecting means with respect to a frequency signal Detecting the phase difference between the frequency signal and the output signal, performing the first drive control for controlling the driving of the vibration type driving device based on the time difference, and vibrating based on the phase difference A step of performing a second drive control for controlling the drive of the mold drive device, and a switching step for performing a switching control of the first and second drive controls.

  Here, in the switching step, switching control may be performed according to the time difference.

  In the switching step, the first drive control may be performed when the time difference is smaller than the predetermined time, and the second drive control may be performed when the time difference is larger than the predetermined time. It is preferable to include a step of detecting a driving speed of the vibration type driving device or a driven member driven by the vibration type driving device, and in the switching step, switching control may be performed according to the driving speed.

  In the switching step, the first drive control may be performed when the drive speed is lower than the predetermined speed, and the second drive control may be performed when the drive speed is higher than the predetermined speed.

  In the switching step, the first drive control may be performed when the vibration type driving device is activated.

  A computer program for causing a computer to execute the control method.

According to the control device of the vibration type driving device of the present invention, since the switching control of the first and second drive control can be performed according to the driving state of the vibration type driving device, an accurate phase can be obtained with a simple configuration. You can control.
Specifically, for example, since the second drive control is performed when the time difference is larger than a predetermined time, it is possible to concentrate on the second drive control. This eliminates the need for a microcomputer or the like), and enables accurate phase control.

  In addition, for example, by performing the second drive control when the drive speed is higher than a predetermined speed, it is possible to concentrate on the second drive control, so that accurate phase control is performed with a simple configuration. be able to.

  According to the first control method of the vibration type drive device of the present invention, the switching control between the first and second drive controls can be performed according to the drive state of the vibration type drive device, so that the configuration is simple. Accurate phase control can be performed.

  Specifically, for example, since the second drive control is performed when the time difference is larger than a predetermined time, it is possible to concentrate on the second drive control. This eliminates the need for a microcomputer or the like), and enables accurate phase control.

  In addition, for example, by performing the second drive control when the drive speed is higher than a predetermined speed, it is possible to concentrate on the second drive control, so that accurate phase control is performed with a simple configuration. be able to.

Embodiments of the present invention will be described below with reference to the drawings.

  In the present embodiment, the operation of each part will be described by taking as an example the case where the present invention is applied to an interchangeable lens autofocus single-lens reflex camera.

FIG. 1 is a block diagram of an interchangeable lens and an autofocus single-lens reflex camera.
As shown in FIG. 1, reference numeral 1 denotes an interchangeable lens, 2 denotes a focus lens unit capable of moving back and forth in the optical axis direction, and the focus lens unit 2 holds a focus lens 4.

  Reference numeral 3 denotes a vibration wave motor as an actuator of the focus lens unit 2.

  Reference numeral 5 denotes a booster circuit (reference power supply for the oscillatory wave motor) that generates a reference voltage to be applied to the oscillatory wave motor 3, and has a circuit configuration that boosts the battery voltage up to about five times (generally, DC / DC). DC converter).

  Reference numeral 6 denotes a driver circuit that performs power amplification to drive the vibration wave motor 3, which will be described in detail later. Reference numeral 7 denotes a lens microcomputer that controls the entire interchangeable lens 1. The lens microcomputer 7 is equipped with functions such as a communication controller for performing communication with the camera body 10, a timer function, a DAC function, an input / output port, a ROM, and a RAM.

  A moving amount detector 8 detects the rotation amount and rotation speed of the vibration wave motor 3, and cuts out the circumference of the disk rotating in synchronization with the rotation of the vibration wave motor 3 at the same pitch, and uses a photo interrupter element. Thus, a signal change is detected depending on whether the light projected from the LED reaches the light receiving element or is blocked.

  Since the movement amount of the focus lens unit 2 is mechanically proportional to the rotation amount of the vibration wave motor 3, the movement amount of the focus lens unit 2 can be detected by counting the number of pitches described above. .

  Further, the time interval of the pitch described above is measured, and the speeds of the vibration wave motor 3 and the focus lens unit 2 are detected. Reference numeral 9 denotes a phase difference detector for detecting the phase difference between the AC voltage applied to the vibration wave motor 3 and the S phase described above. The phase difference detector will also be described later.

  Reference numeral 10 denotes a camera body, and 11 denotes a focus detection unit for detecting a focus adjustment state of the photographing optical system. The focus lens unit 4 is driven based on the detection result of the focus detection unit 11 and moves to the in-focus position.

  A camera microcomputer 12 controls the entire camera. Reference numeral 13 denotes a mechanical switch for instructing the camera user to focus and release. In this embodiment, only an operation method for focusing on the present invention will be described. Although the camera body 10 has various other functions, they are omitted because they are not related to this embodiment.

  Reference numeral 14 denotes a contact unit for enabling communication between the camera body 10 and the interchangeable lens 1. The contact unit 14 includes a plurality of metal projections provided on the camera body 10 and a plurality of electrical pieces provided on the interchangeable lens 1, and each metal projection is in contact with each electrical piece. As a result, the camera microcomputer 12 and the lens microcomputer 7 become conductive. Note that the lens 1 can be removed from the camera body 10 because the metal protrusion and the electrical piece are merely in mechanical contact.

  The camera microcomputer 12 detects the AF start switch SW13, waits until an instruction to start autofocus is received from the user, and takes in the focus adjustment data detected by the focus detection unit 11 when there is an instruction thereafter. The focus detection unit 11 detects the amount of defocus (defocus amount) from the distance to the subject and the current position of the focus lens unit 2 through the focus lens 4 incorporated in the focus lens unit 2.

  The camera microcomputer 12 calculates the drive amount of the focus lens unit 2 in accordance with the detected focus shift amount, and communicates with the lens microcomputer 7 through the contact unit 14.

  The lens microcomputer 7 activates the booster circuit 5 and applies a voltage of about 30 V to the driver circuit 6. When a voltage is applied to the driver circuit 6, the lens microcomputer 7 uses the internal timer function to output a drive waveform in which the A phase and the B phase are shifted by 90 degrees at a specific frequency. Driven to start the movement of the focus lens unit 2.

  The timer function can change the frequency, and gradually decreases the frequency to increase the rotation speed of the vibration wave motor 3. The lens microcomputer 7 always monitors the movement amount detector 8 and compares it with the movement amount transmitted from the camera microcomputer 12. If they match as a result of the comparison, it is determined that the focus lens unit 2 has moved by a predetermined movement amount, and the drive of the vibration wave motor 3 is stopped.

  The change in the output of the movement detector 8 is measured by a timer function inside the lens microcomputer 7 and compared with a time value corresponding to a target speed (target rotation speed) set in advance in a memory inside the lens microcomputer. Rotational speed control of the vibration wave motor 3 by frequency change (same as the moving speed control of the focus lens unit 2) is performed.

  In addition, the lens microcomputer 7 always detects the phase state of the vibration wave motor 3 with the phase difference detector 9, and the two phase data held in advance in the lens microcomputer 7 (respectively PLE2 and PLE1, respectively) are set to the resonance frequency of the vibration wave motor. If the near side is set to PLE1 (see FIG. 3), the frequency scanning is stopped even when the target speed is not reached when the frequency is far from the resonance frequency (the phase of PLE2).

  As a result of the comparison, when the resonance frequency is further approached (the phase of PLE1), the frequency is set to a higher side than the present, and the vibration wave motor drive is controlled to be away from the resonance frequency.

Here, how to use PLE2 and PLE1 which are the gist of the present invention will be described.
Until now, the time difference between the A phase or the B phase and the S phase (hereinafter, the relationship between the B phase and the S phase is referred to as a phase difference) is approximated as a phase difference. It is necessary to detect the phase difference. However, in order to detect a true phase difference, it is necessary to divide by the lens microcomputer 7, and in the case of a microcomputer without a divider, the calculation time increases.

  Therefore, when the vibration wave motor 3 is driven in a high frequency region, it is determined that the phase is relatively far from the resonance frequency (see FIG. 3). In this state, an accurate phase difference is not necessary, so approximation by time difference. It is possible to control the value as a phase.

  In other words, when applied in the acceleration region-constant speed region-deceleration region in general motor control, the phase detection based on the time difference can be performed in the acceleration region or the deceleration region even in the case of the vibration wave motor.

  In addition, since this region must frequently change the frequency, it is also a region where the performance in terms of control of the lens microcomputer 7 is necessary. Conversely, in the constant speed region, the vibration wave motor also rotates at a high speed, so that it is close to the resonance frequency, and accurate phase detection is required.

  Although the speed is high, it is a stable speed range, so it is not necessary to change the frequency so much, and the control performance of the lens microcomputer 7 may be reduced.

  Thereby, true phase difference detection can be performed in the constant speed region. The data of PLE1 and PLE2 at this time must have a time value for time difference detection and an angle for phase difference detection. In addition, if the PLE2 (comparison value far from the resonance frequency) already used is used for switching between the time difference and the phase difference, it is not necessary to add new phase difference comparison data.

  FIG. 4 is a diagram showing in detail the electric circuit of the driver circuit 6, the phase detector 9, the booster circuit 5, and the lens microcomputer 7 for operating the vibration wave motor. This electric circuit is of a type that controls the speed of the vibration wave motor by changing the frequency. The operation of this circuit will be described with reference to FIG.

  Reference numeral 51 denotes a microcomputer (hereinafter referred to as a microcomputer) which is a lens microcomputer 7 that controls the vibration wave motor 3. As functions of the microcomputer 51, a frequency generator function for generating a frequency to be applied to the vibration wave motor and a timer counter function (with a signal capture function) for detecting the phase of the vibration wave motor are provided.

  A step-up DCDC converter unit 52 is a power circuit applied to the vibration wave motor 3. This circuit is configured so that the microcomputer 51 can control the operation / non-operation. 53 is a power source (battery), and 54 is a regulator for stably supplying the power source 53, which is supplied to the microcomputer 51 and also used as a reference power source for phase detection.

  55 is an inverter on the A phase side of the vibration wave motor 3, 56 is an inverter on the B phase side of the vibration wave motor 3, 57 is an NPN transistor for supplying power on the A phase side of the vibration wave motor 3, and 58 is a vibration wave An NPN transistor for supplying power on the B phase side of the motor 3, 59 is an NPN transistor on the A phase side of the vibration wave motor, and 60 is an NPN transistor on the B phase side of the vibration wave motor 3.

  The input of the A-phase side inverter 55 and the base of the A-phase side NPN transistor 59 are respectively connected to the A-phase side frequency generator output terminal of the microcomputer 51, and the output of the inverter 55 is connected to the base of the NPN transistor 57. With this output logic, power is sunk / sourced to the phase A side of the vibration wave motor.

  Similarly, the input of the B-phase side inverter 56 and the base of the B-phase side NPN transistor 60 are respectively connected to the B-phase side frequency generator output terminal of the microcomputer 51, and the output of the inverter 56 is connected to the base of the NPN transistor 58, The power is sinked / sourced to the B phase side of the vibration wave motor by the output logic of the microcomputer 51.

  61 is an A phase side coil, 62 is a B phase side coil, 63 is an A phase side capacitor, and 64 is a B phase side capacitor.

  By connecting the A-phase side coil 61 and the A-phase side capacitor 63 in series with the power source, a boosted voltage corresponding to the applied frequency is applied to the A-phase of the vibration wave motor.

  Similarly, a step-up voltage corresponding to the frequency applied by connecting the B-phase side coil 62 and the B-phase side capacitor 64 in series with the power supply is applied to the B-phase of the vibration wave motor 3.

  65 is an A phase side electrode of the vibration wave motor 3, 66 is a B phase side electrode of the vibration wave motor, 67 is an S phase electrode of the vibration wave motor, 68 is a piezoelectric element, and 69 is a GND electrode. The piezoelectric element 68 is distorted by applying a voltage to the A phase and the B phase, and by changing the phase of the B phase with respect to the A phase by ± 90 °, elliptical motion is generated on the contact surface with the rotating portion, and the rotating portion rotates. This is the principle of the vibration wave motor.

  Reference numeral 70 denotes a voltage dividing circuit for halving the voltage of the regulator 54, and forms a threshold voltage of the comparator. Reference numerals 71 and 72 are resistances for level shift of the B phase voltage. 73 and 75 form a high-pass filter for the S phase of the vibration wave motor 3, and 74 and 76 form a high-pass filter for the B phase of the vibration wave motor 3, respectively.

  Reference numeral 77 denotes a B-phase comparator of the vibration wave motor 3, which performs level shifting to the voltage of the regulator 54 and performs B-phase waveform shaping. Reference numeral 78 denotes an S-phase comparator of the vibration wave motor 3, which performs level shifting to the voltage of the regulator 54 and performs S-phase waveform shaping.

  FIG. 2 illustrates waveforms output from the comparators 77 and 78. When the vibration wave motor 3 is driven near the resonance point, the phase difference between the S phase and the B phase is generally reduced. The control method will be described below with reference to FIGS.

  When the microcomputer 51 drives the vibration wave motor 3, the DC / DC converter unit 52 is operated to increase the voltage of the power supply 53. Normally, the voltage is boosted about 5 times here.

  Next, the microcomputer 51 activates an internal frequency generator circuit to generate an output in which the phase is changed by ± 90 ° between the A phase and the B phase. The transistors 57, 58, 59 and 60 are controlled by this output. For example, when the A-phase logic voltage output from the microcomputer 51 is at a high level, the output logic of the inverter 55 is at a Lo level, and the transistor 57 is turned off.

  The transistor 58 is turned on, and the voltage applied to the A phase of the vibration wave motor 3 is lowered. Conversely, when the A-phase logic voltage output from the microcomputer 51 is 0 V, the output logic of the inverter 55 becomes Hi level, and the transistor 57 is turned on. The transistor 58 is turned off, and the voltage applied to the A phase of the vibration wave motor increases.

  Next, an AC voltage is supplied to the coils 61 and 62 by these operations, and the voltage applied to the vibration wave motor 3 is further boosted by the capacitors 63 and 64. Normally, the voltage is boosted about 3 to 4 times before being applied to the vibration wave motor.

  When a voltage is input, the vibration wave motor starts to start at a specific frequency due to its characteristics. The microcomputer 51 measures the elapsed time with an internal timer counter until the start is started, and detects and outputs the outputs of the comparators 77 and 78 when a preset time elapses. Therefore, the timer counter is set and started for phase detection. .

  From FIG. 5, the timer counter is configured to start counting by the rising signal of the output of the comparator 57 and store the current timer counter value in the internal memory by the rising signal of the comparator 58.

  In addition, the period data for the S phase signal change is also taken in and stored in the internal memory of the microcomputer 51 in case the phase detection is switched from the time difference to the phase difference. Here, since phase difference detection originally requires an operation by a divider, a microcomputer having a high function and a high processing speed must be selected.

However, as described above, the acceleration or deceleration region is considered far from the resonance frequency, and the time difference is approximated as a phase difference in order to concentrate on acceleration and deceleration control.
The microcomputer 51 compares the phase difference data of the B phase and S phase stored in the internal memory with a preset value, and if it is less than that value, the current drive frequency is fixed (the data to be compared is currently Time value is used for time difference detection, and angle is used for phase detection).

  By moving the vibration wave motor away from the resonance point by these phase detection controls, it is possible to prohibit exceeding the resonance point.

  FIG. 5 is a flowchart showing the internal processing of the camera microcomputer 12. Further explanation will be continued based on FIG.

(Step 101, 102)
The camera microcomputer 12 detects the state of the switches and writes the detection result in a memory inside the microcomputer. The camera body 10 has many switches such as a lens mounting switch, a release switch, a mode switching switch, and a dial switch as switches. In this embodiment, an autofocus start switch and a lens mounting switch (not shown) are related. Others are irrelevant and will not be described.

  The autofocus start switch is a push button type two-stage stroke switch, and recognizes that the switch is turned on by the first stroke operation. The lens mounting switch (not shown) is a mechanism that is turned on when the interchangeable lens is mounted on a mount portion (not shown) provided on the front surface of the camera body 10 and pushed by the lens mount.

(Step 103)
The camera microcomputer 12 determines whether the interchangeable lens 1 is mounted from the signal of a lens mounting switch (not shown) detected in step 102. If the interchangeable lens 1 is not attached, the process returns to step 102 and continues to detect switches.

(Step 104)
When the interchangeable lens 1 is mounted, the lens information held by the lens microcomputer 7 is received from the lens microcomputer 7 through the contact unit 14 by communication. The lens information is sensitivity information necessary for calculating the amount of movement of the focus lens unit 2 for focusing on the subject as a result of the focus detection unit 11 detecting the focus adjustment state of the photographing optical system (this embodiment) (The ratio information of the moving amount of the focus on the film surface with respect to the moving amount of the focus lens unit 2). The lens microcomputer 7 is loaded with various other information, but the description thereof is omitted in this embodiment.

(Step 105)
It is determined from the signal of the autofocus start switch 13 detected in step 102 whether the user has instructed the start of autofocus. If not, the process returns to step 102.

(Step 106)
If it is determined in step 105 that the user has instructed the start of autofocus, the focus detection unit 11 obtains data on the amount of deviation of the focus lens position relative to the subject position on the focus surface. In this embodiment, the focus detection unit 11 always repeats focus detection in order to shorten the autofocus time (if the user supports autofocus start and starts focus detection, a slight time lag occurs. ).

(Step 107)
The camera microcomputer 12 determines from the focus detection data obtained in step 106 whether the subject is in focus. If the subject is in focus, a warning device (not shown) notifies the user that the user is in focus, and the process returns to step 102. The warning may be performed by a sound warning using a piezoelectric buzzer or light emitted from an LED.

(Step 108)
If the subject is not in focus, the focus lens unit 2 for focusing on the subject with the focus lens unit 2 based on the focus detection data obtained in step 106 and the sensitivity information of the interchangeable lens 1 obtained in step 104. Calculate the amount of movement.

(Step 109)
When the movement amount is calculated in step 108, a lens driving command is transmitted from the camera microcomputer 12 to the lens microcomputer 7 via the contact unit 8.

(Step 110)
The camera microcomputer 12 transmits the movement direction and movement amount of the focus lens unit 2 to the lens microcomputer 7 via the contact unit 8.

(Step 111)
The movement state of the focus lens unit 2 is received through the contact unit 8 and waits until the movement of the focus lens unit 2 is completed. When the movement of the focus lens unit 2 is completed, the process returns to step 102.

  FIG. 6 is a flowchart of the program of the lens microcomputer 7. The operation of the interchangeable lens 1 will be described with reference to FIG.

(Steps 201 and 202)
The lens microcomputer 7 detects the state of various switches and writes the detection result in a memory inside the microcomputer. Many switches such as an auto focus / manual focus switch (not shown), an absolute distance detection switch, and a zoom position detection switch (not shown) in the case of a zoom lens are mounted on the switch. The description is omitted in the example.

(Step 203)
If the focus lens unit 2 is currently being driven, the process proceeds to step 207, and if not, the process proceeds to step 204.

(Step 204)
It is determined whether or not a drive command for the focus lens unit 2 has been received from the camera microcomputer 12. If received, the process proceeds to step 205. If not received, the process returns to step 202.

(Step 205)
After the drive command is received, the focus lens unit 2 is kept on standby without being driven until the drive amount is received. Then, after receiving the driving amount, the process proceeds to step 206.

(Step 206)
Since the lens microcomputer 7 drives the vibration wave motor 3, the driving direction is determined based on the driving amount received from the camera microcomputer 12, and a frequency signal whose phase is shifted by ± 90 ° along the driving direction is sent to the driver circuit 6. Supply. The focus lens unit 2 starts to be moved by driving the vibration wave motor 3. In addition, a setting is made to perform approximate phase detection based on a time difference at the same time as the motor is started (because it is known that it is far from the resonance point at the time of startup).

(Step 207)
The lens microcomputer 7 detects an output change time interval from the movement amount detector 8 with an internal timer of the lens microcomputer 7, detects whether the focus lens unit 2 is moving at a preset moving speed, and focuses. The moving speed of the lens unit 2 is controlled.

  Next, the lens microcomputer 7 always detects a signal from the phase difference detector 9 and simultaneously monitors the phase state of the vibration wave motor 3. As described in step 206, since it is known that the motor is far from the resonance point when the motor is started, the time difference is approximated as a phase difference, and the performance of the lens microcomputer 7 is concentrated on other controls.

  The setting phase of PLE2 is compared with the current phase, and if it is determined that the current phase is large (not exceeding PLE2), a setting for performing approximate phase detection based on a time difference is performed, and the process proceeds to step 208.

  Here, the reason for resetting the phase detection method is that the phase detection by calculation is switched from the phase detection by calculation to the phase detection by time difference by the deceleration control when the focus lens unit 2 approaches the predetermined movement amount. Because. In the deceleration control, the frequency applied to the vibration wave motor 3 needs to be scanned to the higher side, and the lens microcomputer 7 is devoted to the deceleration (speed) control rather than the phase control.

(Step 208)
In step 205, whether the focus lens unit 2 has moved by the amount of movement instructed by the camera microcomputer 12 is compared with the count number output from the movement amount detector 8. When the count number from the movement amount detector 8 does not coincide with the movement amount transmitted from the camera microcomputer 12, the routine proceeds to step 202.

(Step 209)
When the count number from the movement amount detector 8 coincides with the movement amount transmitted from the camera microcomputer 12, the application of the frequency to the vibration wave motor 3 is stopped to stop the movement of the focus lens unit 2. Return.

(Step 210)
In step 207, the lens microcomputer 7 always detects the signal from the phase difference detector 9 and monitors the phase state of the vibration wave motor 3. The set phase of PLE2 described above is compared with the current phase, and if it is determined that the current phase is small (exceeds PLE2), it is determined that the vibration wave motor 3 is close to the resonance point, and the phase is more accurately determined. Switch to the phase detection method by calculation (angle) to perform detection. At this time, the motor is rotating at high speed, but has reached the speed stable range, so it is not necessary to change the frequency so much, and the lens microcomputer 7 can be dedicated to phase detection.

  In the first embodiment, the phase detection method based on the time difference and the calculation is compared with the setting data of the PLE 2 and is switched. It is known that fluctuations occur. Similarly, the electric circuit that performs phase detection also switches between phase detection methods when the rotational speed of the vibration wave motor reaches a predetermined value, or when both the speed and phase are used, considering individual variations and fluctuations due to environmental changes. Is considered safer. Therefore, this embodiment employs a method other than switching by phase detection.

FIG. 1 is a block diagram of an interchangeable lens and an autofocus single-lens reflex camera.
Since the description of each function in the figure is the same as that of the first embodiment, the description is omitted.
The camera microcomputer 12 detects the AF start switch SW13, waits until an instruction to start autofocus is received from the user, and takes in data from the focus detection unit 11 when there is an instruction.

  The focus detection unit 11 detects the amount of focus shift from the distance to the subject and the current position of the focus lens unit 2 through the focus lens 4 incorporated in the focus lens unit 2. The camera microcomputer 12 calculates the driving amount of the focus lens unit 2 for focusing from the detected focus shift amount, and communicates with the lens microcomputer 7 through the contact unit 14.

  The lens microcomputer 7 activates the booster circuit 5 and applies a voltage of about 30 V to the driver circuit 6. When a voltage is applied to the driver circuit 6, the lens microcomputer 7 uses the internal timer function to output a drive waveform in which the A phase and the B phase are shifted by 90 degrees at a specific frequency to drive the vibration wave motor 3. Then, the movement of the focus lens unit 2 is started. The timer function can change the frequency, gradually lowering the frequency and increasing the rotation speed of the vibration wave motor.

  The lens microcomputer 7 always monitors the movement amount detector 8 and compares it with the movement amount transmitted from the camera microcomputer 12. If they match as a result of the comparison, it is determined that the focus lens unit 2 has moved by a predetermined movement amount, and the drive of the vibration wave motor 3 is stopped.

  The change in the output of the movement detector 8 is measured by a timer function inside the lens microcomputer 7 and compared with a time value corresponding to a target speed (target rotation speed) set in advance in a memory inside the lens microcomputer. Rotational speed control of the vibration wave motor 3 by frequency change (same as the moving speed control of the focus lens unit 2) is performed.

  In addition, the lens microcomputer 7 always detects the phase state of the vibration wave motor 3 by the phase difference detector 9, and two phase data (previously referred to as PLE2 and PLE1 respectively) stored in the lens microcomputer 7 are used as the resonance frequency of the vibration wave motor 3. When the frequency near the resonance frequency is set to PLE1 (see FIG. 3), the frequency scan is stopped even when the target speed is not reached.

  Further, as a result of comparison, when the resonance frequency is further approached (the phase of PLE1), the frequency is set to a higher side than the present, and the vibration wave motor drive is controlled away from the resonance frequency.

  Here, how to use PLE2 and PLE1 which are the gist of the present invention will be described. Until now, the time difference between the A phase or the B phase and the S phase (hereinafter referred to as the relationship between the B phase and the S phase) is approximated as a phase difference. However, as the speed of the vibration wave motor 3 increases, It is necessary to detect an accurate phase difference. However, in order to detect a true phase difference, it is necessary to divide by the lens microcomputer 7, and in the case of a microcomputer without a divider, the calculation time increases.

  Therefore, when the vibration wave motor is driven in a high frequency region, it is determined that the phase is relatively far from the resonance frequency (see FIG. 3), and an accurate phase difference is not necessary in this state. Can be considered as a phase and controlled.

  In other words, when applied in the acceleration region-constant speed region-deceleration region in general motor control, even in the case of the vibration wave motor 3, the phase can be detected by the time difference in the acceleration region or the deceleration region. Further, since the frequency must be frequently changed in this area, the performance of the lens microcomputer 7 in terms of control is also a necessary area.

  Conversely, in the constant speed region, the vibration wave motor also rotates at a high speed, so that it is close to the resonance frequency, and accurate phase detection is required. Although it is high in speed, it is not necessary to change the frequency so much because it is in a stable speed range, and the control performance of the lens microcomputer 7 may be reduced.

  Therefore, true phase difference detection can be performed in the constant speed region. The data of PLE1 and PLE2 at this time must have a time value for time difference detection and an angle for phase difference detection. In order to switch between the time difference and the phase difference, the output change of the movement detector 8 is measured by the timer function inside the lens microcomputer 7 and the phase detection switching time (= speed) set in the memory inside the lens microcomputer in advance. = Time of rotation). This makes it possible to remove various variables due to environmental changes. In combination with the phase detection method of the first embodiment, the change can be further reduced by performing switching by OR logic.

FIG. 4 shows an example of an electric circuit for explaining in detail the parts of the driver circuit 6, the phase detector 9, the booster circuit 5 and the lens microcomputer 7 for operating the vibration wave motor.
Since the functions and operations in the figure are also the same as those in the first embodiment, description thereof will be omitted.

FIG. 5 is a flowchart showing the internal processing of the camera microcomputer 12.
Since the operation contents of the figure are the same as those of the first embodiment, the description thereof is omitted.

  FIG. 7 is a flowchart of the program of the lens microcomputer 7. The operation of the interchangeable lens 1 will be described with reference to FIG.

(Steps 301 and 302)
The lens microcomputer 7 detects the state of various switches and writes the detection result in a memory inside the microcomputer. Many switches such as an auto focus / manual focus switch (not shown), an absolute distance detection switch, and a zoom position detection switch (not shown) in the case of a zoom lens are mounted on the switch. The explanation is omitted because it is irrelevant.

(Step 303)
If the focus lens unit is currently being driven, the process proceeds to step 307, and if not, the process proceeds to step 304.

(Step 304)
It is determined whether a drive command for the focus lens unit 2 has been received from the camera microcomputer 12. If received, the process proceeds to step 305. If not received, the process returns to step 302.

(Step 305)
After the drive command is received, the focus lens unit 2 is kept on standby without being driven until the drive amount is received. Then, after receiving the driving amount, the process proceeds to step 306.

(Step 306)
Since the lens microcomputer 7 drives the vibration wave motor 3, the driving direction is determined based on the driving amount received from the camera microcomputer 12, and a frequency signal having a phase shift of ± 90 ° along the driving direction is supplied to the driver circuit 6. To do. The focus lens unit 2 starts to be moved by driving the vibration wave motor 3. In addition, a setting is made to detect the approximate phase based on the time difference at the same time as the motor is started (because it is known that it is far from the resonance point at the time of startup).

(Step 307)
The lens microcomputer 7 detects the time interval of the output change from the movement amount detector 8 with the internal timer of the lens microcomputer 7, detects whether the focus lens unit 2 is moving at a preset moving speed, and the focus lens. The moving speed control of the unit 2 is performed.

  Next, the lens microcomputer 7 always detects a signal from the phase difference detector 9 and simultaneously monitors the phase state of the vibration wave motor 3. As described in step 306, since it is known that the motor is far from the resonance point when the motor is started, the time difference is approximated as a phase difference, and the performance of the lens microcomputer 7 is concentrated on other controls.

  If the current speed is slow compared to the previously detected movement speed of the focus lens unit 2 (the rotation speed of the vibration wave motor is the same) and the phase detection switching speed (which may be time) held in the lens microcomputer 7 in advance. If it is determined, the setting for performing the approximate phase detection based on the time difference is performed, and the process proceeds to Step 308.

  Here, the reason for resetting the phase detection method is that the phase detection by calculation is switched from the phase detection by calculation to the phase detection by time difference by the deceleration control when the focus lens unit 2 approaches the predetermined movement amount. Because. In the deceleration control, the frequency applied to the vibration wave motor 3 needs to be scanned to the higher side, and the lens microcomputer 7 is devoted to the deceleration (speed) control rather than the phase control.

  Here, not only the speed but also, for example, the movement amount of the vibration wave motor is detected by the movement amount detection 8, and when the predetermined movement amount is reached, the frequency value that determines the rotation speed of the vibration wave motor reaches a predetermined frequency, There is a method of measuring the time from activation with a timer and shifting to step 308 after a predetermined time has elapsed.

  Since these are irrelevant to phase detection, including speed switching, it is possible to switch, for example, by stopping the phase detection process at startup and restarting the phase detection method with these detection methods. This eliminates the need to perform the phase detection process at the time of starting the motor, so that the performance of the lens microcomputer 7 can be further improved.

(Step 308)
In step 305, it is determined whether the focus lens unit 2 has moved by the movement amount instructed from the camera microcomputer 12 by comparing it with the count number output from the movement amount detector 8. If the count number from the movement amount detector 8 does not match the movement amount transmitted from the camera microcomputer 12, the process returns to step 302, and if it matches, the process proceeds to step 309.

(Step 309)
When the count number from the movement amount detector 8 matches the movement amount transmitted from the camera microcomputer 12, the application of the frequency to the vibration wave motor 3 is stopped to stop the movement of the focus lens unit 2, and step 302 is performed. Return to.

(Step 310)
In step 307, the lens microcomputer 7 constantly detects the signal from the phase difference detector 9 and monitors the phase state of the vibration wave motor 3. Compared to the moving speed of the focus lens unit 2 detected in step 307 (the rotational speed of the vibration wave motor is the same) and the phase detection switching speed (which may be time) previously held in the lens microcomputer 7, the current speed is faster. Is determined, the vibration wave motor 3 is determined to be close to the resonance point, and the phase detection method is switched to the calculation (angle) in order to perform phase detection with higher accuracy.

  At this time, the motor is rotating at high speed, but has reached the speed stable range, so it is not necessary to change the frequency so much, and the lens microcomputer 7 can be dedicated to phase detection.

  As described above, in this embodiment, accurate phase control that does not exceed the resonance frequency is performed with a relatively inexpensive configuration in excitation detection control in which an excitation detection unit (S phase) is provided in a part of the vibration body of the vibration wave motor. Can be provided.

Internal circuit block diagram of a general AF single-lens reflex camera and interchangeable lens when using a vibration wave motor Signal diagram when waveform shaping of B phase and S phase of vibration wave motor Relationship diagram between general frequency and rotational speed of vibration wave motor Example of vibration wave motor drive circuit Flowchart diagram of camera microcomputer Lens microcomputer flowchart Flowchart of the microcomputer of the lens of the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interchangeable lens 2 Focus lens unit 3 Vibration wave motor 4 Focus lens 5 Booster circuit 6 Driver circuit 7 Lens microcomputer 8 Movement amount detector 9 Phase difference detector 10 Camera body 11 Focus detection unit 12 Camera microcomputer 13 Autofocus start switch 14 Contact unit

Claims (15)

A vibration type driving device having a vibrating body whose vibration is excited by an electro-mechanical energy conversion element to which a frequency signal is applied, and a contact body in contact with the vibrating body, and relatively driving the vibrating body and the contact body A control device of
Vibration detecting means for detecting a vibration state of the vibrating body;
A time difference detecting means for detecting a time difference which is a delay time of an output signal from the vibration detecting means with respect to the frequency signal;
Phase difference detection means for detecting a phase difference between the frequency signal and the output signal;
Drive control means for performing a first drive control for controlling the drive of the vibration type drive device based on the time difference and a second drive control for controlling the drive of the vibration type drive device based on the phase difference;
And a switching control means for performing switching control of the first and second driving controls.   The control device for a vibration type driving device according to claim 1, wherein the switching control means performs the switching control according to the time difference.   The switching control means causes the drive control means to perform the first drive control when the time difference is smaller than a predetermined time, and causes the drive control means to perform the second drive when the time difference is larger than the predetermined time. The control device for the vibration type driving device according to claim 2, wherein control is performed. Speed detecting means for detecting a driving speed of the vibration type driving device or a driven member driven by the vibration type driving device;
2. The control device for a vibration type driving device according to claim 1, wherein the switching control means performs the switching control according to the driving speed.   The switching control means causes the drive control means to perform the first drive control when the drive speed is lower than a predetermined speed, and causes the drive control means to perform the second drive when the drive speed is higher than the predetermined speed. The control device for the vibration type drive device according to claim 4, wherein the drive control is performed.   6. The vibration type drive according to claim 1, wherein the switching control unit causes the drive control unit to perform the first drive control when the vibration type drive device is started. 6. Control device for the device. A control device according to any one of claims 1 to 6;
The vibration type driving device;
An apparatus using a vibration type driving device, comprising: a driven member driven by the vibration type driving device. A control device according to any one of claims 1 to 6;
The vibration type driving device;
And an optical member driven by the vibration type driving device. An optical apparatus using the vibration type driving device. A vibration type driving device having a vibrating body whose vibration is excited by an electro-mechanical energy conversion element to which a frequency signal is applied, and a contact body in contact with the vibrating body, and relatively driving the vibrating body and the contact body Control method,
Detecting a vibration state of the vibrating body;
Detecting a time difference which is a delay time of an output signal from the vibration detecting means with respect to the frequency signal;
Detecting a phase difference between the frequency signal and the output signal;
Performing a first drive control for controlling the drive of the vibration type drive device based on the time difference;
Performing a second drive control for controlling the drive of the vibration type drive device based on the phase difference;
And a switching step for performing switching control between the first and second drive controls.   The method for controlling the vibration type driving device according to claim 9, wherein the switching control is performed according to the time difference in the switching step.   2. The switching step, wherein the first drive control is performed when the time difference is smaller than a predetermined time, and the second drive control is performed when the time difference is larger than the predetermined time. A control method of the vibration type driving device according to claim 10. Detecting a driving speed of the vibration type driving device or a driven member driven by the vibration type driving device;
The method for controlling a vibration type driving device according to claim 9, wherein the switching control is performed according to the driving speed in the switching step.   In the switching step, the first drive control is performed when the drive speed is lower than a predetermined speed, and the second drive control is performed when the drive speed is higher than the predetermined speed. The method for controlling the vibration type driving device according to claim 12.   The method of controlling a vibration type driving device according to any one of claims 9 to 13, wherein, in the switching step, the first driving control is performed when the vibration type driving device is activated.   A control program for a vibration type driving apparatus, characterized in that the control program is a computer program for causing a computer to execute the control method according to any one of claims 9 to 14.

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