JP3849031B2 - Vibration device and device provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration device having vibration type driving means called a vibration type motor, an ultrasonic motor or the like, and more particularly to control of the vibration type driving means.
[0002]
[Prior art]
The vibration type driving means includes a vibrating body to which an electro-mechanical energy conversion element is attached and a vibrating body that is pressed against the vibrating body, and applies a frequency signal to the electro-mechanical energy conversion element to the vibrating body. The vibration is excited and both are moved relative to each other by friction between the vibrating body and the contact body. Such a vibration type driving means is used for driving a photosensitive drum of a copying machine because of its excellent operation stability at a low speed.
[0003]
Japanese Patent Application Laid-Open Nos. 7-143775 and 7-143777 propose a device that detects the vibration state of the vibrating body, controls the frequency of the frequency signal, and controls the operating speed of the vibration type driving means. Has been.
[0004]
[Problems to be solved by the invention]
However, as shown in the graphs of FIGS. 5 and 6, the vibration-type driving means changes the frequency in a region where the frequency of the frequency signal is high, in other words, in a region where the vibration amplitude of the vibrating body is small and the driving speed is low. The amount of change in vibration amplitude and drive speed with respect to the amount is small, but the frequency is low (however, higher than the mechanical resonance point that is the peak of the graph), in other words, the vibration amplitude of the vibrator is large and the drive speed is high. In such a region, there is a characteristic that the amount of change such as vibration amplitude with respect to the amount of change in frequency is large.
[0005]
For this reason, as in the device proposed in the above publication, regardless of the frequency of the frequency signal or the vibration amplitude of the vibrating body, the frequency change amount (control amount associated with one control) is set to be constant. For example, when a high frequency is applied (when small amplitude or low speed driving), the frequency change amount is set so as to obtain a good response, so that when low frequency is applied (when large amplitude or high speed driving), FIG. As shown by the broken line in FIG. 4, the driving speed varies greatly and control stability is lost. There is a problem that it is difficult to achieve both quick response and control stability in a wide operation region, such as slow rise and poor response.
[0006]
Accordingly, an object of the present invention is to provide a control device for a vibration type drive device that can achieve both control speed response and control stability in a wide operating range.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a vibration type driving means for relatively moving a vibrating body excited by vibration by application of a frequency signal to the electromechanical energy conversion element and a contact body in contact with the vibrating body; In a vibration device having a frequency control means for controlling the frequency of a frequency signal by detecting the vibration state of the body or the operation speed of the driving device, the frequency control means increases the detected vibration state or the operation speed and the frequency. The frequency change amount setting is changed according to whether the frequency is decreased .
[0008]
Specifically, in a region where the vibration amplitude of the detected vibrating body is large or a region where the operating speed of the driving device is high, the operating speed does not fluctuate greatly by a single control by setting a small amount of change in frequency. While ensuring control stability, in a region where the vibration amplitude of the vibrating body is small or a region where the operating speed of the driving device is low, by setting a large amount of change in frequency, the operating speed can be greatly changed by one control. Responsiveness is obtained so that both control speed and control stability can be achieved in a wide operating range. Moreover, the amount of change in the frequency is changed between when the frequency is increased (when the operating speed is reduced) and when the frequency is decreased (when the operating speed is accelerated). Thereby, precise speed control can be performed.
[0009]
In the present invention, by providing such a control device, it is possible to realize a device such as a copying machine that can smoothly start up rotation of the photosensitive drum and the like and can quickly obtain stable rotation. Yes.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In FIG. 1, the structure of the vibration apparatus which is 1st Embodiment of this invention is shown. In the present embodiment, a case where the vibration device is used for driving a photosensitive drum of a copying machine will be described.
[0011]
In FIG. 1, reference numeral 1 denotes a vibration type motor (vibration type driving means). The vibration type motor 1 includes a ring-shaped vibrating body to which two-phase electro-mechanical energy conversion elements 2a and 2b are attached, and a moving body (contact body) (not shown) that is in pressure contact with the vibrating body. It is configured. Between the two-phase conversion elements 2a and 2b in the vibrating body, a ground phase 2d and an amplitude detection mechanical-electrical energy conversion element (hereinafter referred to as a detection element) 2c are attached.
[0012]
Reference numeral 11 denotes a control unit, and the control unit 11 includes a microprocessor unit (MPU) 9 and a memory 10 connected thereto.
[0013]
Reference numeral 6 denotes an amplitude calculator. The amplitude calculator 6 calculates the vibration amplitude of the vibrating body based on the detection signal output from the detection element 2c according to the vibration of the vibrating body, and outputs a signal corresponding to the calculation result. Input to the microprocessor unit 9. The control unit 11 and the amplitude calculator 6 correspond to frequency control means in the claims.
[0014]
Reference numeral 8 denotes a D / A converter. The D / A converter 8 outputs an analog voltage signal corresponding to output data of the microprocessor unit 9. Reference numeral 7 denotes a voltage controlled oscillator. The voltage controlled oscillator 7 outputs a rectangular wave signal having a frequency proportional to the analog signal output from the D / A converter 8.
[0015]
Reference numeral 5 denotes a waveform shaper. The waveform shaper 5 generates and outputs two sine wave signals having the same phase from the rectangular wave signal output from the voltage controlled oscillator 7. One of the two sine wave signals generated by the waveform shaper 5 is directly input to the amplifier 3a, the other is input to the 90 ° phase shifter 4, and the one sine is 90 ° to the signal. The phase is shifted and input to the amplifier 3b. Two sine wave signals amplified to a required level by the amplifiers 3a and 3b are applied to the conversion elements 2a and 2b, respectively.
[0016]
Thus, when the sine wave signal is applied to the conversion elements 2a and 2b, the conversion elements 2a and 2b expand and contract to excite vibrations in the vibrating body, and the moving body vibrates due to friction between the vibrating body and the moving body. It is rotationally driven with respect to the body. The rotational force of the moving body is transmitted to the photosensitive drum 15 and rotationally driven.
[0017]
The microprocessor unit 9 changes the output data to the D / A converter 8 according to the vibration amplitude of the vibrating body calculated by the amplitude calculator 6. As a result, the frequency of the sine wave signal applied to each of the conversion elements 2a and 2b is changed and set, and control is performed with good rise response at start-up and good stability at high speed.
[0018]
Here, the change setting control of the frequency of the sine wave signal in the microprocessor unit 9 will be described with reference to the flowchart shown in FIG. First, in step (abbreviated as S in the figure) 1, the frequency of the sine wave signal is set to the initial frequency fo, and the vibration type motor 1 is started. Next, in step 2, the vibration amplitude is monitored, and in step 3, the frequency change amount Δf corresponding to the monitored vibration amplitude is set. As shown in FIG. 3, the frequency change amount Δf is determined in advance to be set to a larger value as the amplitude is smaller.
[0019]
In step 4, it is determined whether or not a speed increase command is input. If the speed increase command is input, the process proceeds to step 6 to decrease the drive frequency by Δf set in step 3. On the other hand, when the speed increase command is not input, the process proceeds to step 5 to determine whether or not the speed reduction command is input. When the deceleration command is input, the process proceeds to step 7 and the drive frequency is increased by Δf set in step 3.
[0020]
In this way, the drive frequency is set according to the magnitude of the vibration amplitude, but the larger the vibration amplitude, the smaller the frequency change amount is set. The change amount (gain) of the vibration amplitude obtained by the control (flow) can be made almost constant. Therefore, in the region where the vibration amplitude is large, the fluctuation of the operation speed of the vibration type motor by one control does not become too large, and the control stability can be ensured. Further, in the region where the vibration amplitude is small, the fluctuation of the operation speed of the vibration type motor by one control does not become too small, and good responsiveness can be obtained. That is, it is possible to achieve both control speed response and control stability in a wide amplitude range.
[0021]
For this reason, for example, as shown by a solid line in FIG. 4, the vibration type motor quickly rises up to a predetermined speed, and after exceeding the predetermined speed, it can be converged to the predetermined speed with a small speed fluctuation. When the photosensitive drum 15 is driven by the vibration type motor, the rotation of the photosensitive drum can be quickly stabilized at a predetermined speed, and the copying machine can be used early after the copying machine is turned on. it can.
[0022]
As shown in FIG. 3, even if the vibration amplitude read in step 2 is the same, the frequency change amount Δf may be set larger when the frequency is decreased than when the frequency is increased. As can be seen from FIG. 5, in the frequency region above the mechanical resonance point, the higher the frequency, the smaller the amount of change in vibration amplitude with respect to the amount of change in frequency, and the case where the predetermined amount amplitude is increased from the same vibration amplitude. This is because the frequency to be changed becomes larger when decreasing. In addition, by changing the frequency change amount Δf depending on whether the frequency is increased or decreased, precise amplitude control, that is, speed control can be performed, and control speed response and control stability are further improved. be able to.
[0023]
In the above embodiment, the frequency change amount is precisely calculated using the microprocessor. For example, a map having data as shown in FIG. The change amount data corresponding to the amplitude may be read out.
[0024]
In the above-described embodiment, the case where the frequency change amount of the sine wave signal is changed according to the vibration amplitude of the vibrating body has been described. However, the rotational speed of the moving body is detected using an encoder or the like, and the rotational speed is The frequency change amount of the sine wave signal may be changed.
[0025]
Furthermore, in the above-described embodiment, the case where the vibration device is used in a copying machine has been described. However, the vibration device of the present invention can also be used in devices other than copying machines.
[0026]
【The invention's effect】
As described above, according to the present invention, in a region where the vibration amplitude of the detected vibrating body is large or a region where the operating speed of the driving device is high, the frequency change amount of the frequency signal is set small so that the operation by one control is performed. Control stability is ensured by preventing speed fluctuations from becoming too large, and the operating speed can be changed sufficiently by a single control by setting a large amount of frequency change in areas where vibration amplitude is low or operating speed is low. Therefore, good response can be obtained, so that both control speed response and control stability can be achieved in a wide operation region of the vibration type driving means.
[0027]
In the present invention, by providing such a control device, it is possible to realize a device such as a copying machine which can smoothly start up the rotation of the photosensitive drum or the like and quickly obtain a stable rotation.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a control apparatus according to a first embodiment of the present invention.
FIG. 2 is a flowchart for setting a frequency change amount in the vibration device;
FIG. 3 is a graph showing the relationship between the frequency change amount and the vibration amplitude.
FIG. 4 is a graph conceptually showing speed control of the vibration type motor by the control device and the conventional control device.
FIG. 5 is a graph showing the operating characteristics of a conventional vibration type motor.
FIG. 6 is a graph showing operating characteristics of a conventional vibration type motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vibration type motor 2a, 2b Electro-mechanical energy conversion element 2c Detection element 2d Ground phase 3a, 3b Amplifier 4 90 degree phase shifter 5 Waveform shaper 6 Amplitude calculator 7 Voltage control oscillator 8 D / A converter 9 Microprocessor Unit 10 memory

Claims (6)

Vibration type driving means for relatively moving a vibrating body whose vibration is excited by application of a frequency signal to the electro-mechanical energy conversion element and a contact body in contact with the vibrating body; and detecting a vibration state of the vibrating body. In the vibration device having a frequency control means for controlling the frequency of the frequency signal,
The frequency control means changes the setting of the change amount of the frequency according to the detected vibration state and whether the frequency is increased or decreased . The vibration state is amplitude;
2. The vibration device according to claim 1, wherein the frequency control unit decreases the setting of the change amount of the frequency as the detected amplitude increases. Vibration-type driving means for relatively moving a vibrating body whose vibration is excited by application of a frequency signal to the electromechanical energy conversion element and a contact body in contact with the vibrating body; and a relative relationship between the vibrating body and the contact body. In a vibration device having a frequency control means for detecting the moving speed and controlling the frequency of the frequency signal,
The frequency control means changes the setting of the amount of change of the frequency according to the detected relative movement speed and whether the frequency is increased or decreased .   4. The vibration device according to claim 3, wherein the frequency control unit decreases the setting of the change amount of the frequency as the detected relative movement speed increases. 5. The vibration device according to claim 1, wherein the frequency control unit sets the change amount of the frequency to be larger when the frequency is decreased than when the frequency is increased. 6. Apparatus characterized by comprising a vibration device according to any one of claims 1 to 5.

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