JP3768664B2 - Drive device for vibration type actuator, apparatus using vibration type actuator, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a drive device for a vibration type actuator such as a vibration type motor that applies a driving force using vibration energy generated in a vibration body by applying an alternating signal to an electromechanical energy conversion element, and a vibration type actuator. The application of vibration type actuators to equipment and image forming devices, especially electrophotographic image forming devices, such as photosensitive drums as image carriers in copying machines, which require high accuracy with respect to rotational speed It is related to the device.
[0002]
[Prior art]
Conventionally, speed control of a vibration type actuator, particularly a vibration type motor, has been performed by proportional-integral control or integral control similar to other motors.
[0003]
For example, in Japanese Patent Laid-Open No. 7-131987, as shown in FIG. 5, a piezoelectric element 56 constituting a vibrating body having a two-phase drive unit is connected to a power amplifier 39, 41 through 90 degrees from a power amplifier 39, 41 via a matching coil 42, 45. An alternating voltage as an alternating signal whose phase is shifted by 90 degrees is applied through the drive electrode 46 by the phase shifter 40. One drive signal and the other drive signal are also used to detect the vibration state, and the added value of both is supplied to one input side of the operational amplifier 50 via the capacitors 44 and 47, and the other of the piezoelectric element 56 A signal (ground voltage) from the pole side is input to the other input side of the operational amplifier 50, and rotational speed information is output from the operational amplifier 50. The output from the operational amplifier 50 is input to one input side of another operational amplifier 52 through a rectifier 51, and the speed set value from the speed setting means 53 is input to the other input side of the operational amplifier 52. The speed difference is input to the integrator 55.
[0004]
Then, the adder 54 adds the difference value from the operational amplifier 52 and the integration value obtained by the integrator 55, and adjusts the driving frequency of the vibration type motor output from the voltage controlled oscillator 38 by this value to adjust the speed. Is controlling.
[0005]
[Problems to be solved by the invention]
By the way, when a vibration type motor is used to drive a photosensitive drum of a copying machine, the movement distance of the photosensitive drum surface, that is, an error in the rotation angle affects the printing accuracy. In the above-described conventional technique, when a speed fluctuation is given due to a disturbance or the like, as shown in FIG. 4A, the steady-state error (Δv) of the speed may be finally reduced to zero with respect to the speed deviation. However, the stationary error (Δx) of the dimension of the position obtained by integrating the speed shown in FIG. 4B cannot be reduced to zero, that is, the positional deviation caused by the speed fluctuation is restored (between two points). If the speed fluctuates during movement, even if the speed returns to the target speed, the target position cannot be reached for a predetermined time) and it may not be possible to perform good printing. .
[0006]
That is, in the case of one-color copying, when the toner image on the photosensitive drum is transferred to the transfer material at the transfer position, the toner image is not transferred to the normal position with respect to the transfer material.
[0007]
Further, in the case of color copying, in the configuration in which the photosensitive drums carrying the toner images of the respective colors (four colors) are arranged in parallel along the moving direction of the transfer material, the transfer position of the toner image with respect to the transfer material is shifted. Cause color shift.
[0008]
An object of the first invention according to the present application is to provide a driving device for a vibration type actuator that can make both steady position errors zero with a simple configuration by utilizing the high response of the vibration type motor. To do.
[0009]
The object of the second invention according to the present application is to drive a vibration type actuator that can make both the steady state error of the velocity and the steady state error of the position zero with a simple configuration by utilizing the high responsiveness of the vibration type motor. The device is to be provided.
[0010]
An object of the third invention according to the present application is to provide a device including a vibration type actuator capable of driving a driven body with both steady-state error and steady-state position error set to zero.
[0011]
A fourth object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image when driving a photosensitive drum or the like using a vibration type actuator as a drive source.
[0013]
[Means for Solving the Problems]
  According to this application1st andA first configuration that realizes the object of the second invention is a vibration type actuator that obtains a driving force by exciting the electro-mechanical energy conversion element by applying a frequency signal.DrivingIn the apparatus, a detecting means for detecting a driving state of the vibration type actuator, a calculating means for calculating a difference between the driving state obtained from the detecting means and a predetermined state, and integrating a value obtained from the calculating means First integrating means, second integrating means for integrating the values obtained from the first integrating means, values output from the first integrating means, and outputs from the second integrating means. And an addition means for adding a value to be adjusted, and an amount of energy supplied to the electromechanical energy conversion element is adjusted in accordance with an output from the addition means.
[0014]
  The second configuration for realizing the object of the second invention according to the present application is as follows:,Proportional means for adding a proportional element to the value obtained from the calculation meansHave,The adding means includesAdd the value output from the first integrating means, the value output from the second integrating means, and the value output from the proportional meansDoIt is what I did.
[0015]
In the above configuration, the detection means is means for detecting any of speed, acceleration, position, and vibration state of the vibration type actuator.
[0016]
In the above configuration, an integration time constant or a magnification of integration data is set for one or both of the first integration means and the second integration means, and obtained from the first and second integration means. The operation amount for the vibration type actuator is determined by using the obtained value and the set integration time constant or magnification.
[0017]
Said structure WHEREIN: As a means to adjust the energy supplied to the said electromechanical energy conversion element, it changes by changing the frequency of the frequency signal applied to the said electromechanical energy conversion element.
[0018]
In the above configuration, as means for adjusting energy supplied to the electro-mechanical energy conversion element, a voltage amplitude of a frequency signal applied to the electro-mechanical energy conversion element, or a value capable of changing the voltage amplitude is set. It is done by changing.
[0019]
In the above configuration, as means for adjusting energy supplied to the electro-mechanical energy conversion element, the phase difference of a plurality of frequency signals applied to the electro-mechanical energy conversion element is changed.
[0020]
A first configuration that realizes the object of the third invention according to the present application includes any one of the above-described vibration type actuator driving devices, and the driven body is driven by the vibration type actuator. is there.
[0021]
A second configuration for realizing the object of the third invention related to the present application has a plurality of driving devices for any of the vibration type actuators described above, and drives a plurality of driven bodies by the plurality of vibration type actuators, respectively. It is what you do.
[0022]
A first configuration for realizing the object of the fourth invention according to the present application includes any one of the above-described vibration type actuator driving devices, and uses the vibration type actuator as a drive source of the image carrier. .
[0023]
A second configuration that realizes the object of the fourth invention according to the present application includes any one of the above-described vibration type actuator driving devices, and a plurality of image carriers arranged along the transfer material conveyance direction. The vibration type actuators are used as the drive sources and the drive sources of the transfer material conveying means.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 2 is a diagram showing the overall configuration of the color image forming apparatus used in the first embodiment of the present invention. The configuration of the color image forming apparatus will be described below with reference to FIG.
[0025]
First, the configuration of the reader unit will be described.
[0026]
In FIG. 2, 101 is a CCD, 311 is a substrate on which the CCD 101 is mounted, 312 is a printer processing unit, 301 is a platen glass, 302 is a document feeder, 303 and 304 are light sources for authenticating a document, and 305 and 306 are A reflector for condensing light from the light source (303, 304) on the document, 307 to 309 are mirrors, 310 is a lens for condensing reflected light or projection light from the document on the CCD 101, and 314 is a light source (303, 304). , A carriage accommodating the reflectors (305, 306) and the mirror 307, a carriage 315 accommodating the mirror (308, 309), and an interface unit 313 for interfacing with other IPUs.
[0027]
The carriage 314 is moved at a speed V and the carriage 315 is mechanically moved at a speed V / 2 in the direction perpendicular to the electrical scanning (main scanning) direction of the CCD 101, thereby scanning (sub-scanning) the entire surface of the document.
[0028]
The document on the platen glass reflects light from the light source (303, 304), and the reflected light is guided to the CCD 101 and converted into an electrical signal. The electrical signal (analog image signal) is input to the image processing unit 312 and converted into a digital signal. The converted digital signal is processed and then sent to the printer unit to be used for image formation.
[0029]
Next, the configuration of the printer unit will be described.
[0030]
In FIG. 2, 317 is an M (magenta) image forming unit, 318 is a C (cyan) image forming unit, 319 is a Y (yellow) image forming unit 320, and a K (black) image forming unit. Are the same, the M image forming unit 317 will be described, and the description of the other image forming units will be omitted.
[0031]
In the M image forming unit 317, reference numeral 342 denotes a photosensitive drum as an image carrier, and a latent image is formed on the surface by light from the LED array 210. Reference numeral 321 denotes a primary charger that charges the surface of the photosensitive drum 342 to a predetermined potential to prepare for latent image formation. A developing device 322 develops a latent image on the photosensitive drum 342 to form a toner image. The developing device 322 includes a sleeve 345 for developing by applying a developing bias. A transfer charger 323 discharges from the back surface of the endless belt-shaped transfer material conveyance belt 333 that conveys the transfer material, and transfers the toner image on the photosensitive drum 342 to a recording sheet or the like on the transfer material conveyance belt 333. . In the present embodiment, since the transfer efficiency is good, a conventionally used cleaner is not arranged. Needless to say, there is no problem even if the cleaner is mounted.
[0032]
Next, a procedure for forming an image on recording paper or the like will be described. The recording paper or the like stored in the cassettes (340, 341) is supplied onto the transfer material conveying belt 333 by the sheet feeding rollers (336, 337) one by one by the pickup rollers (339, 338). The fed recording paper is charged by an adsorption charger 346. Reference numeral 348 denotes a transfer bell and a roller, which drives the transfer bell and 333 and charges the recording paper or the like in a pair with the adsorption charger 346 to adsorb the recording paper or the like on the transfer material conveyance belt 333. Reference numeral 347 denotes a paper front end sensor that detects the front end of the recording paper on the transfer material conveyance belt 333. The detection signal of the paper leading edge sensor is sent from the printer unit to the color reader unit, and is used as a sub-scanning synchronization signal when a video signal is sent from the color reader unit to the printer unit.
[0033]
Thereafter, the recording paper or the like is conveyed by the transfer material conveying belt 333, and toner images are formed on the surface of the image forming units 317 to 320 in the order of MCYK. In order to facilitate separation from the transfer material conveyance belt 333, the recording paper or the like that has passed through the K image forming unit 320 is discharged from the transfer material conveyance belt 333 after being neutralized by the neutralization charger 349.
[0034]
A peeling charger 350 prevents image disturbance due to peeling discharge when the recording paper or the like is separated from the transfer material conveying belt 333. The separated recording paper or the like is charged by the pre-fixing chargers (351, 352) and then the toner image is thermally fixed by the fixing device 334 in order to compensate for the toner adsorption force and prevent image disturbance. 335 is discharged to a paper discharge tray 335.
[0035]
Here, as a drive motor for rotating the photosensitive drums (342 to 345) and the transfer material conveying belt roller 348, a known vibration type motor which is a kind of vibration type motor is used.
[0036]
A vibration type motor is a circular or elliptical motion on the surface of an elastic body by applying an alternating signal as an alternating signal to a piezoelectric element as an electro-mechanical energy conversion element fixed to the elastic body constituting the vibrating body, for example. , And the vibrating body is moved relative to the contact body in pressure contact therewith. In addition, when the vibrating body is a stator and the contact body is a rotor, there is a type in which an output shaft provided at the rotation center of the rotor is connected to the rotor and output is taken out from the output shaft. In this embodiment, a vibration type actuator having this output shaft is used.
[0037]
FIG. 3 is a diagram showing a connection state between the photosensitive drum and the vibration type motor. In FIG. 3, 9 is a vibration type motor. A rotary encoder 8 outputs the rotation angle of the output shaft of the vibration motor 9 as pulse information. Reference numeral 10 denotes a photosensitive drum.
[0038]
FIG. 1 is a control block diagram of a vibration type motor according to the first embodiment of the present invention, and FIG. 16 shows a drive unit for one vibration type motor shown in FIG. 1 and a plurality of photosensitive drums in the image forming apparatus of FIG. And a configuration when used for driving a transfer material conveying belt. Hereinafter, each block of FIG. 1 will be described.
[0039]
In FIG. 1, reference numeral 1 denotes a speed difference detector, which detects a difference between a driving speed and a speed command value obtained based on pulse information obtained from a rotary encoder 7 connected to the output shaft of the vibration type motor 6. Output. An example of this speed difference detector is shown in FIG. The speed difference detector shown in FIG. 6 is formed by a synchronous logic circuit, and 11 and 12 are D flip-flops. When the D input of the D flip-flop 12 is at a high level and the Q output is at a low level, it is detected as a rising edge of an input pulse from the encoder. At this time, the output from the AND 14 is at a high level for the period of one clock cycle.
[0040]
In the 16-bit down counter 15, the target speed data is loaded when the output of the AND 14 is at a high level, that is, one clock cycle after the rising edge of the encoder, and down count is performed otherwise. The target speed data sets the number of counts when one cycle of the encoder pulse is counted by the clock when operating at the target speed. The target speed data v is obtained by the following formula.
[0041]
v = fc / (N × Ep) −1
Here, fc is the clock frequency [Hz], N is the target rotational speed [1 / s], and Ep is the number of encoder output pulses per revolution [P / R]. For example, in the case of an encoder that outputs a target frequency of 1 [1 / s], a clock frequency of 10 [MHz], and a motor rotation of 2000 pulses, the target speed data is 4999.
[0042]
The 16-bit register 16 is written with the value of the counter 15 one clock cycle after the edge of the encoder is detected. At the moment when data is written in the register 16, the target speed is not yet loaded in the counter 15, and the count value until immediately before the encoder edge is detected is written.
[0043]
The output (bar) Q of the register 16 outputs inverted data of the stored value. By the operation as described above, the time from the rising edge of the encoder to the next rising edge is counted, and a value minus 1 minus the target speed data,
Ie
Te × fc-v-1
Is output from the register 16.
[0044]
Here, v is target speed data, Te is a cycle [sec] of a pulse output from the encoder, and fc is a clock frequency [Hz].
[0045]
Returning to FIG. 1, the speed difference data detected as described above is input to the first integrator 2. FIG. 7 is a circuit diagram showing the internal configuration of the first integrator 2. In the control circuit of the present embodiment, the integration time constants of the integrator 2 and the integrator 3 are set as control parameters that can be adjusted.
[0046]
In FIG. 7, 16 'is an 8-bit down counter, and when the data becomes 0, the carry output C becomes high level. At this time, integration time constant data is loaded, and then down-counting is performed. With the above operation, the down counter 16 'constitutes a ring counter with the integration time constant data as a cycle.
[0047]
The carry output C of the down counter 16 'outputs a signal that becomes high level for one cycle of the clock once in one cycle of the ring counter.
[0048]
17 is a 16-bit adder. The adder 17 adds 16-bit input A and input B data, and outputs the added data from the output S. The output data becomes the data input of the 16-bit register 18.
[0049]
The register 18 loads data at the timing of the integration time constant output from the down counter. As a result, integration data corresponding to the integration time constant is output from the Q output of the register 18.
[0050]
Although the description has been omitted for the sake of brevity in the present embodiment, an upper limit value and a lower limit value are given to a circuit for initializing integration data and an integration result before driving the vibration type motor in the integrator described above. Therefore, a configuration that prevents integration data from overflowing is actually required.
[0051]
Returning to FIG. 1, reference numeral 3 denotes a second integrator, which has an internal structure similar to that of the first integrator 2 described above. The second integrator 3 integrates the data integrated by the first integrator 2 with an integration time constant determined separately from the first integrator 2.
[0052]
Reference numeral 37 denotes an adder. The adder 37 is a 16-bit adder similar to the adder 17 shown in FIG. The adder 37 adds the data obtained by integrating the speed difference data by the first integrator 2 and the data integrated by the second integrator 3. Data output from the adder 37 is an operation amount.
[0053]
In the present embodiment, the frequency of the AC voltage applied to the vibration type motor is used as the operation amount for controlling the speed of the vibration type motor.
[0054]
FIG. 11 shows the relationship between the rotational speed of the vibration type motor and the frequency of the AC voltage applied to the vibration type motor. As shown in FIG. 11, the rotational speed reaches a peak at the resonance frequency fr of the vibration type motor. Further, since the frequency is higher than the resonance frequency fr and the characteristics are gentle and the control is relatively easy, the control is usually performed in a frequency region higher than the resonance frequency fr.
[0055]
Returning to FIG. 1, reference numeral 4 denotes a pulse generator that outputs a four-phase pulse signal having a predetermined pulse width at the frequency output from the adder 37. FIG. 8 is a circuit diagram showing the internal configuration of the pulse generator 4.
[0056]
In FIG. 8, 19 is a 16-bit down counter. When the count value reaches 0, the down counter 19 outputs a high level from the C output. When a high level is output from the C output, the load input LD of the down counter 19 becomes a high level, so that the frequency data is loaded into the counter. Thereafter, the down counter 19 counts down.
[0057]
With the above configuration, the carry output C of the down counter 19 outputs a signal that is at a high level only for one cycle of the clock with the frequency data as one cycle.
[0058]
In the present embodiment, although described as frequency data, a value corresponding to the cycle of the drive frequency is actually input. Further, since one cycle of the driving AC wave of the vibration type motor corresponds to four cycles of the down counter 19, the frequency data sets a value corresponding to a quarter cycle of the driving frequency of the vibration type motor. The carry output C of the down counter 19 is input as the enable signal EN of the 2-bit counter 20.
[0059]
The counter 20 counts up each time the carry signal of the counter 19 is output. The count value repeats 4 states from 0 to 3. The outputs Q0 and Q1 of the counter are input to a decoder 21 having a 2-bit input and 4-bit output.
[0060]
In the decoder 21, when the input G is at a low level, all the outputs Q0 to Q3 are at a low level. When the input G is at a high level, the output of any of Q0 to Q3 is at a high level depending on the combination of the input A and the input B.
[0061]
When both inputs A and B are low, Q0 is high. When input A is high and input B is low, Q1 is high. When input A is low and input B is high. When Q2 is at a high level and both inputs A and B are at a high level, the output Q3 is at a high level.
[0062]
With the above configuration, when the carry output C having one cycle of the frequency data output from the down counter 19 is at a high level, Q0 to Q3 are sequentially output to be at a high level for the duration of one cycle of the clock cycle. The
[0063]
The outputs Q0 to Q3 of the decoder 21 are input to the set inputs S of the RS flip-flops 22 to 25.
[0064]
The RS flip-flops 22 to 25 hold the values until the output Q is at a high level when each set input is at a high level, and thereafter the reset input R is at a high level. The carry output C of the 16-bit down counter 26 is input to the reset inputs R of the RS flip-flops 22 to 25.
[0065]
The down counter 26 is used to determine the length of the pulse width. When the output Q of the RS flip-flops 22 to 25 becomes high level, that is, when the carry output C of the down counter 19 becomes high level, the high level is input to the load input LD of the down counter 26.
[0066]
When a high level is input to the load input LD of the down counter 26, pulse width data input from the outside is loaded into the down counter 26. This pulse width data is given a fixed value or a predetermined value from a controller (not shown).
[0067]
The pulse width data must be smaller than the frequency data described above. With the configuration as described above, the down counter 26 becomes high level after the pulse width data has elapsed since any output Q of the RS flip-flop becomes high level.
[0068]
With the above operation, the outputs A1, A2, B1, and B2 from the pulse generator are output as pulses having a pulse width corresponding to the pulse width data at a period four times the frequency data. FIG. 9 shows a timing chart showing the outputs A1, A2, B1, and B2. As shown in FIG. 9, A1 and A2, and B1 and B2 are pulses having a phase difference of 180 °. A1 and B1, and A2 and B2 each have a pulse width having a phase difference of 90 °. The four-phase pulses output from the pulse generator are input to the booster 5 in FIG.
[0069]
FIG. 10 is a circuit diagram showing the internal configuration of the boosting means. The step-up means 5 is for generating a two-phase AC wave for driving the vibration type motor based on the pulse signal from the pulse generator 4. The two-phase AC wave has the same frequency, a voltage amplitude of about 300 Vp-p, and a signal having a phase difference of 90 ° in time.
[0070]
In FIG. 10, 27a, 27b, 27c, and 27d are FETs. 27a and 27b are FETs for generating an A-phase drive signal, and 27c and 27d are FETs for generating a B-phase drive signal.
[0071]
28a and 28b are transformers with a center tap. In FIG. 10, the center tap electrode on the primary side of the transformer 28a is connected to the power supply voltage. The power supply voltage is a DC voltage generated by a switching regulator or the like in the device.
[0072]
In the image forming apparatus of the present embodiment, 24V is used. The remaining two electrodes on the primary side are connected to the drains of the FETs 27a and 27b, respectively. The FET 27a is driven by the pulse signal A1 output from the pulse generator described above, and the FET 27b is driven by the pulse signal A2. As a result, current flows alternately from the center tap to the other two ends on the primary side of the transformer 28a.
[0073]
An AC signal corresponding to the step-up rate of the transformer 28 is generated on the secondary side of the transformer 28. This is the A-phase AC wave output. Similarly, a B-phase AC wave output is also generated. By using the four-phase pulse signals as described in FIG. 9 as the gate signals of the FETs 27a to 27d, the A-phase AC wave output and the B-phase AC wave output in FIG. 10 have a phase difference of 90 ° in time. Signal. The AC signal of the phase generated by the above configuration is input to the vibration type motor 6 of FIG.
[0074]
The vibration type motor 6 is driven on the principle as described above. As shown in FIG. 3, a rotary encoder 9 is connected to one of the output shafts of the vibration type motor 9. A pulse signal corresponding to the rotational speed output from the encoder 9 is input to the speed difference detector 1 of FIG.
[0075]
With the above configuration, a feedback loop is formed so that the rotational speed of the vibration type motor is constant.
[0076]
In the present embodiment, the two integrators of the first integrator 2 and the second integrator 3 are used for the speed deviation, and the integral value of the first integrator 2 is directly input to the adder 37, whereby FIG. 4 (c), the steady-state deviation of the target speed is set to zero, and the double integral value obtained by integrating the integral value of the first integrator 2 with the second integrator is input to the adder 37. As shown in (d), the stationary error of the position with respect to the target value can also be made zero.
[0077]
Therefore, when driving the photosensitive drums and transfer material conveyance belts of the respective colors of the color copying machine shown in FIG. 2 with a vibration type motor, for example, if the leading edge of the transfer material enters the nip portion with the photosensitive drum at the transfer position, A load is applied, resulting in a decrease in speed. If the state is left as it is, the transfer position of the toner image with respect to the transfer material also shifts. Here, the speed itself detected by the speed difference detector 1 and integrated by the first integrator 2 causes the detected speed to become the speed command value, but the function of recovering the delay due to the speed reduction is as follows. Absent.
[0078]
However, by integrating the integral value of the first integrator 2 with the second integrator 3, the obtained double integral value functions to recover the delay.
[0079]
That is, as shown in FIGS. 4C and 4D, the signal output from the adder 37 to the pulse generator 4 is, for example, a target rotation angle within a predetermined time for the rotation angle of the vibration type motor 6. The position deviation is set to 0, and the speed deviation is set to 0 so that the speed becomes the target speed at that time.
[0080]
Accordingly, not only the speed deviation of all the photosensitive drums is set to 0, but also the steady-state error with respect to the target value of the moving distance of the photosensitive drum when forming an image on the photosensitive drum can be reduced to zero.
[0081]
By the way, when a control system using two integrators as described above is configured as a speed control system of an electromagnetic motor, the phase delay of the open loop transmission characteristic becomes large and the system becomes unstable.
[0082]
However, the vibration type motor does not cause such a problem because the response is quicker than the electromagnetic motor. In other words, compared to an electromagnetic motor that uses a heavy coil for the rotor, a vibration type motor that does not use such a heavy object for the rotor has a small inertial force, and the coil of the electromagnetic motor has an inductance element. Therefore, the generation of the magnetic field is delayed. However, since the vibration type motor uses the vibration generated by applying a voltage to the piezoelectric element for driving, the above-mentioned response is fast.
[0083]
(Second Embodiment)
FIG. 12 is a block diagram showing a second embodiment of the present invention.
[0084]
In the first embodiment, the arithmetic part of the control system is configured by a digital circuit, but in the second embodiment, as shown in FIG. 12, the control system is realized by a microcomputer.
[0085]
In the present embodiment, A is a memory inside the microprocessor used for performing the first integration, and B is a memory used for performing the second integration. FIG. 13 is a flowchart showing the internal operation of the microcomputer 29. Hereinafter, the operation of the microprocessor will be described with reference to FIG.
[0086]
The microprocessor performs two operations: an operation at the time of starting the vibration type motor and an operation of performing speed control after the start-up. First, the operation at startup will be described.
[0087]
In response to an external start command for the vibration type motor, the driving of STEP 1 is started.
[0088]
In STEP 2, the value of the memory A inside the microprocessor used as the storage means when performing the first integration operation is set to zero.
[0089]
In STEP 3, the initial value is substituted for the value of the memory B inside the microprocessor used as the storage means when performing the second integration operation.
[0090]
In STEP 4, a value obtained by multiplying the value set in the memory B initialized in STEP 3 by the gain K2 for the second integrating means is determined as the frequency command. This frequency is the frequency of the AC voltage that is first applied to the vibration type motor at the start-up, and this frequency is referred to as the initial frequency. The initial frequency is a frequency near the vibration mode when driving the vibration type motor, and a frequency value higher than the resonance frequency fr in the vibration mode is set. The determined frequency command is output to the pulse generator 4 in FIG.
[0091]
In STEP 5, the drive pulse width is specified. This drive pulse width is the width of a pulse input to the gate terminals of the FETs 27a to 27d described with reference to FIG. The pulse width set here uses the same value until the vibration type motor stops. The determined pulse width is output to the pulse generator 4 in FIG.
[0092]
In STEP 6, a driving voltage is applied to the vibration type motor. Before this step, a gate circuit (not shown) prevents a pulse from being output to the gate terminals of the FETs 27a to 27d, and a pulse is output to the gate terminal after this step. This step may be performed by turning on the voltage of the power source input to the temporary side of the transformers 28a and 28b.
[0093]
After performing the above steps, the start operation of STEP 7 is completed.
[0094]
Next, the operation during control will be described. At the time of control, the timer interrupt is used to change the frequency given to the vibration type motor at regular intervals. In STEP 8, a timer interrupt has occurred.
[0095]
In STEP 9, speed difference data (referred to as ΔV) is taken from the speed difference detector 1 of FIG.
[0096]
In STEP 10, in order to integrate the memory A in which the result of the first integration is stored, A + B is substituted into the value of the second integration memory B after calculation.
[0097]
In STEP 11, A + ΔV is substituted into the memory A after calculation in order to perform the first integration. The reason why the memory B is calculated in STEP 10 before the calculation for the memory A in STEP 11 is that the second integration operation is performed based on the first integration result determined by the previous timer interruption.
[0098]
In STEP 12, the drive frequency is determined by the following equation from the memories A and B in which the integration results are stored.
[0099]
f = K1 × A + K2 × B
Here, f is drive frequency data to be determined, K1 is a control gain for the first integration result, and K2 is a control gain for the second integration result. After the drive frequency is determined, the determined value is output to the pulse generator 4 in FIG.
[0100]
When the above operation is completed, the interrupt operation of STEP 13 is completed, and the process waits until the next timer interrupt occurs. When the next timer interruption occurs, the process proceeds to STEP 8 and the control is performed again. The above-described operation is executed until the motor is stopped.
[0101]
By controlling the vibration motor with the above configuration, it is possible to perform the same control as in the first embodiment of the present invention, and the same effect as in the first embodiment can be obtained.
[0102]
(Third embodiment)
FIG. 14 is a flowchart showing the third embodiment of the present invention. Except for the flowchart, the second embodiment is the same as the second embodiment of the present invention. The flowchart of this embodiment is the same as that of the second embodiment except for the method of determining the drive frequency of STEP 12, and therefore only STEP 12 will be described.
[0103]
In STEP 12, the driving frequency is determined using the following equation.
[0104]
f = K1 × A + K2 × B + K3 × ΔV
Here, the K3 × ΔV portion different from the second embodiment is obtained by adding a proportional element in order to improve the responsiveness in the second embodiment, and K3 is a proportional gain. By performing the control with the above configuration, the same effects as those of the first and second embodiments of the present invention can be obtained, and in addition, responsiveness can be improved.
[0105]
(Fourth embodiment)
FIG. 15 is a flowchart showing the fourth embodiment of the present invention. As in the second and third embodiments, the control block performs control with the configuration shown in FIG.
[0106]
In the first to third embodiments, the speed of the vibration type motor is controlled by manipulating the frequency of the vibration type motor, but in this embodiment, the pulse width data input to the pulse generator is manipulated. The speed is controlled accordingly. Hereinafter, the operation of the fourth embodiment will be described with reference to FIG.
[0107]
The microprocessor performs two operations: an operation at the time of starting the vibration type motor and an operation of performing speed control after the start-up. First, the operation at startup will be described.
[0108]
When an activation command for the vibration type motor is issued from outside, the driving of STEP 1 is started.
[0109]
In STEP2, the value of the memory A inside the microprocessor used as the storage means when performing the first integration operation is set to zero.
[0110]
In STEP 3, the initial value is substituted for the value of the memory B inside the microprocessor used as the storage means when performing the second integration operation.
[0111]
In STEP 4, a value obtained by multiplying the value set in the memory B initialized in STEP 3 by the gain K2 for the second integrating means is determined as the pulse width command. This pulse width becomes the pulse width of the AC voltage first applied to the vibration type motor at the start-up. The determined pulse width command is output to the pulse generator 4 in FIG.
[0112]
In STEP 5, the drive frequency is specified. The driving frequency is selected such that the vibration motor can be sufficiently driven at the target speed. The frequency that can be sufficiently driven here means a frequency that rotates faster than the target speed when a large value is selected for the pulse width, and can be rotated at the target speed by adjusting the pulse width. The determined frequency is output to the pulse generator 4 in FIG.
[0113]
In STEP 6, a voltage is applied to the vibration type motor. Before this step, a gate circuit (not shown) prevents a pulse from being output to the gate terminal of the FET, and a pulse is output to the gate terminal after this step. This step may be performed by turning on the voltage of the power source input to the temporary side of the transformer.
[0114]
After performing the above steps, the start operation of STEP 7 is completed.
[0115]
Next, the operation during control will be described. At the time of control, the timer interrupt is used to change the pulse width given to the vibration type motor at regular intervals. In STEP 8, a timer interrupt has occurred.
[0116]
In STEP 9, speed difference data (referred to as ΔV) is taken from the speed difference detector 1 of FIG.
[0117]
In STEP 10, in order to integrate the memory A in which the result of the first integration is stored, the value of the second integration memory B is substituted after calculating A + B.
[0118]
In STEP 11, A + ΔV is substituted into the memory A after calculation in order to perform the first integration. The reason why the memory B is calculated in STEP 10 before the calculation for the memory A in STEP 11 is that the second integration operation is performed based on the first integration result determined by the previous timer interruption.
[0119]
In STEP 12, the pulse width is determined by the following equation from the memories A and B in which the integration results are stored.
[0120]
p = K1 × A + K2 × B
Here, p is pulse width data to be determined, K1 is a control gain for the first integration result, and K2 is a control gain for the second integration result. After the drive pulse width is determined, the determined value is output to the pulse generator 4 in FIG.
[0121]
When the above operation is completed, the interrupt operation of STEP 13 is completed, and the process waits until the next timer interrupt occurs. When the next timer interruption occurs, the process proceeds to STEP 8 and the control is performed again. The above-described operation is executed until the motor is stopped.
[0122]
Control equivalent to the first and second embodiments described above can be performed by controlling the vibration type motor with the above-described configuration. Further, when the vibration type motor is controlled by manipulating the pulse width as in the present embodiment, the control may be performed in consideration of the proportional term as in the third embodiment.
[0123]
Although the explanation is omitted, the vibration motor can control the speed by manipulating the phase difference between the two-phase AC voltages to be applied, but the frequency or pulse width explained in the embodiment of the present invention is manipulated. Instead of this, the phase difference may be manipulated to control the speed of the vibration type motor.
[0124]
Furthermore, in the embodiment of the present invention described above, the drive circuit is controlled using a logic circuit or a microprocessor. However, the means for realizing the present invention is not limited to these, and a deviation using an integrator is used. This may be performed for all means that can determine the manipulated variable using the value obtained by integrating the value and the value obtained by further integrating the result of the integration.
[0125]
The speed is detected as a detecting means for detecting the driving state of the vibration type actuator. However, the acceleration, position, and vibration state of the vibration type actuator are detected, and a difference from the reference value is obtained. You may make it integrate by an integration means.
[0126]
【The invention's effect】
  As described above, in the first and second inventions according to the present application, the first integrating means and the first integrating means for integrating the deviation data obtained from the driving state detecting means when driving the vibration type actuator. By controlling using the second integration means for integrating the value obtained from(speed)Integration of deviation data as well as steady-state error(position)The steady-state error can be made zero.
[0127]
  Claims4In the invention according to the above, by setting the integration time constant or magnification of the integrator, it is possible to adjust the control accuracy and stability in the apparatus using the vibration type actuator.
[0128]
  Claim5In the invention according to the above, control can be performed by changing the frequency of the frequency signal applied to the vibration type actuator as a means for adjusting the energy input to the vibration type actuator.
[0129]
  Claim6In the invention according to the above, control can be performed by changing the voltage amplitude of the frequency signal applied to the vibration type actuator as a means for adjusting the energy input to the vibration type actuator.
[0130]
  Claim7In the invention according to the above, control can be performed by changing the phase difference between the two-phase frequency signals applied to the vibration type actuator as a means for adjusting the energy input to the vibration type actuator.
[0131]
In the third invention according to the present application, the speed of one or a plurality of driven bodies can be controlled to a target speed, and the movement delay of the driven bodies can be recovered.
[0132]
In a fourth invention according to the present application, in an image forming apparatus such as a color copying machine having a photosensitive drum as an image carrier, the rotational speed of the photosensitive drum varies due to an external load or a load variation. However, since the speed of the photosensitive drum can be adjusted and all the printing positions on the transfer material can be adjusted, a high-quality image can be obtained.
[Brief description of the drawings]
FIG. 1 is a control block diagram according to a first embodiment of the present invention.
FIG. 2 is a schematic view of an image forming apparatus used in the first embodiment of the present invention.
3 is a schematic diagram of a driving device for the photosensitive drum in FIG. 2;
FIG. 4 is a graph for explaining a speed deviation and a position deviation.
FIG. 5 is a control block diagram of a conventional vibration type actuator.
6 is a circuit diagram of the speed difference detector of FIG. 1. FIG.
7 is a circuit diagram of the integrator shown in FIG. 1. FIG.
8 is a circuit diagram of the pulse generator of FIG.
9 is a timing chart showing pulses output from the pulse generator of FIG. 8. FIG.
10 is a circuit diagram of the boosting means in FIG. 1. FIG.
FIG. 11 is a graph showing the relationship between the frequency and speed of a vibration type motor.
FIG. 12 is a block diagram of a control device according to second to fourth embodiments of the present invention.
FIG. 13 is a flowchart showing the operation of the microprocessor according to the second embodiment of the present invention.
FIG. 14 is a flowchart showing the operation of the microprocessor according to the third embodiment of the present invention.
FIG. 15 is a flowchart showing the operation of a microprocessor according to the fourth embodiment of the present invention.
16 is a control block diagram in which the control device in FIG. 1 is applied to the image forming apparatus in FIG.
[Explanation of symbols]
1 ... Speed difference detector
2, 3 ... integrator
4 ... Pulse generator
5. Boosting means
6, 9 ... Vibration type motor
7, 8 ... Rotary encoder
10 photosensitive drums
29 ... Microcomputer

Claims (11)

In a drive device for a vibration type actuator that is excited by applying a frequency signal to an electromechanical energy conversion element to obtain a driving force,
Detection means for detecting the drive state of the vibration type actuator, calculation means for calculating a difference between the drive state obtained from the detection means and a predetermined state, and a first value for integrating the value obtained from the calculation means Integrating means, second integrating means for integrating the values obtained from the first integrating means, values output from the first integrating means, and values output from the second integrating means, A vibration type actuator drive device, comprising: an adding means for adding the power to adjust the amount of energy supplied to the electromechanical energy conversion element according to an output from the adding means. A proportional means for adding a proportional element to the value obtained from said calculation means,
Said adding means, according to claim 1, characterized by adding the value output from said first value and said proportional means is output from the value and the second integral means is output from the integrating means vibration type actuator driving device. 3. The vibration actuator driving apparatus according to claim 1, wherein the detection means is means for detecting any one of speed, acceleration, position, and vibration state of the vibration actuator. An integration time constant or an integration data magnification is set for one or both of the first integration means and the second integration means, and the value obtained from the first and second integration means and the setting are set. vibration type actuator driving device according to any one of claims 1 to 3, characterized by determining the manipulated variable with respect to the vibration type actuator by using the integration time constant or factor that is. As means for Chojo the energy supplied to the mechanical energy conversion element, said electro - - the electrical one of claims 1, characterized in that performed by changing the frequency of the frequency signal applied to mechanical energy conversion element 4 A drive device for the vibration type actuator according to any one of the above. As means for adjusting the energy supplied to the electro-mechanical energy conversion element, the voltage amplitude of the frequency signal applied to the electro-mechanical energy conversion element or a value that can change the voltage amplitude is changed. vibration type actuator driving device according to claim 1, any one of 4, characterized in that. The means for adjusting energy supplied to the electro-mechanical energy conversion element is performed by changing a phase difference of a plurality of frequency signals applied to the electro-mechanical energy conversion element. 4. The drive device for the vibration type actuator according to claim 1. Device using the vibration type actuator, characterized in that claim 1 from a drive device for a vibration type actuator according to any one of 7, driving a driven member by the vibration type actuator. A plurality of driving device for a vibration type actuator according to any one of claims 1 to 7, the vibration type which is characterized in that so as to respectively drive the plurality of the driven body by said plurality of vibration type actuator Equipment using actuators. A drive device for a vibration type actuator according to any one of claims 1 to 7, the image forming apparatus, characterized in that the vibration-type actuator and a driving source of the image bearing member. A drive unit for the vibration type actuator according to any one of claims 1 to 7 , each drive source of a plurality of image carriers arranged along a transfer material transfer direction, and transfer material transfer means An image forming apparatus using the vibration type actuator for each of the driving sources.

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