JPS62262672A - Oscillatory wave motor - Google Patents

Abstract

PURPOSE:To enhance the generation efficiency of a traveling wave by providing a regulating electrode for regulating a standing wave. CONSTITUTION:Insulated A-phase electrodes A1-A5 and B-phase electrodes B1-B5 are provided, and frequency voltages having phases displaced at 90 deg. are applied to the electrodes to generate a traveling vibration. When the node positions of first and second standing waves generated in the A and B phases are displaced due to irregular rigidity of an electrostrictive element 20 or reso nance frequencies are displaced, regulating electrodes C1-C5 are provided to generate suitable standing waves. The electrodes C1-C5 are selected as required to be opened or shortcircuited.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a photographic wave motor that generates a progressive vibration wave by combining a plurality of standing waves, and particularly relates to the adjustment of each of the standing waves. be.

<Prior art> A vibration wave motor converts the photographing motion that occurs when a frequency voltage is applied to one strain element into a rotational motion or a -dimensional motion, as disclosed in Japanese Patent Laid-Open No. 58-1118682, for example. It is something. Compared to conventional M&N motors, it has attracted attention recently because it does not require windings, has a simpler and more compact structure, can provide high torque even when rotating at low speeds, and has the advantage of having less inertial rotation. The operating principle of the recently invented vibration wave motor driven by progressive vibration waves is as follows.

FIG. 1 shows the configuration of this vibration wave motor broken down into individual elements.

A vibration absorber 4 is attached to the central cylindrical portion 5a of the fixed body 5 that serves as the base.
- A metal annular vibrating body 2 with an electrostrictive element 3 bonded to the absorbing body 4 side and a moving body l are fitted in this order, and the fixed body 5, absorbing body 4, electrostrictive element 3, and vibrating body 2 are mutually connected to each other. It is installed so that it does not rotate. The movable body 1 is pressed against the vibrating body 2 by its own weight or a biasing means (not shown) to maintain the integrity of the motor.

The plurality of electrostrictive elements 3a are arranged at a pitch of 1/2 of the wavelength λ of the vibration wave, and the plurality of electrostrictive elements 3b are also arranged at a pitch of λ/2. J5 electrostrictive element 3a (or 3b
) may be made into a single element without arranging a plurality of them, and the element may be polarized to the above-mentioned pitch.

The mutual pitch between electrostrictive elements 3a and 3b is (n0+t/4)λ
(However, n.=0.1.2.3., .) A shifted phase difference arrangement is made. A lead wire 11 is connected to the absorber 4 side of each electrostrictive element 3a, and a lead wire 11 is connected to each electrostrictive element 3b.
b are connected, and each of them is connected to an AC power source 6a and a 90° phase shifter 6b (see FIG. 2). Also, the metal vibrating body 2
A lead wire 11c is connected to the AC power source 6a.

The friction portion 1a of the vibrating body 1 is made of hard rubber or the like and is pressed against the vibrating body 2 so as to increase the frictional force and reduce wear.

Figure 2 shows the generation of vibration waves in the motor.
The electrostrictive elements 3a and 3b bonded to the metal vibrating body 2 are
For convenience of explanation, they are shown adjacent to each other, but the above λ/4
Since it satisfies the phase shift condition, the arrangement is substantially equivalent to the arrangement of the electrostrictive elements 3a and 3b of the motor shown in FIG. In each of the electrostrictive elements 3a and 3b, ■ indicates that the AC voltage expands when the cycle is on the positive side, and e indicates that the electrostrictive element also contracts when the cycle is on the positive side.

The metal vibrating body 2 is used as one electrode of the electrostrictive elements '3a'EL and 3b, and the electrostrictive element 3a is supplied with V=V from the AC power source 6a.
, sinωt are applied to the electrostrictive element 3b, and an AC voltage of V=V0 (ωt±π/2) with a phase shift of λ/4 is applied from the AC power source 6a through the 90° phase shifter 6b. 10 or - in the formula is moving object 1 (omitted in this figure)
The phase shifter 6b is used to switch the phase shifter 6b depending on the direction in which it is moved.When switched to the + side, the phase shifts by +90 degrees and moves in the positive direction, and when switched to the - side, the phase shifts by 190 degrees and moves in the opposite direction. It is now switched to the - side, and V=V in the electrostrictive element 3b.
, sin (ωt-W/2) are applied. Only the electrostrictive element 3a has voltage ■=■. sinω
When the electrostrictive element 3b vibrates due to t, vibration occurs due to the first standing wave as shown in FIG. 4
', vibrations due to the second standing wave as shown in (b) occur. When the above-mentioned two phase-shifted alternating currents are simultaneously applied to each electrostrictive element 3a and 3b, the vibration wave becomes progressive. (
A) is time t=2nπ/ω, (b) is t=π/2ω+2
nπ/ω, (c) is when t=π/ω+2nπ/ω, and (d) is when t=2π/2ω+2nπ/ω, and the wavefront of such a vibration wave advances in the X direction.

The moving body is frictionally driven by the traveling wave. In the above-mentioned vibration wave motor, single electrostrictive elements are connected to each vibrating body.
The same effect can be obtained even if a ring-shaped electrostrictive element having an endless structure is polarized. In other words, in a polarization type electrostrictive element,
For example, as shown in FIG. 3, the (+) part and (-) part indicate the direction of polarization, respectively, and the length of the circumference of one electrostrictive element 20 is the (+) part and (-) part. It is a natural multiple of the length determined by the sum of , and in the figure it has a circumference six times as large.

In the same figure (b), the TL of the soil surface (vibrating body side) of the electrostrictive element 20 is
The poles 20c extend around the entire circumference so as to have a common potential and are connected to the vibrating body, and in FIG.
f, 20g is shown. 20d is the polarization processing section 20a in the same figure (a), and 20e is the polarization processing section 20b in the same figure (a).
provided at a position corresponding to Reference numeral 20f denotes a detection electrode for detecting vibrations of the electrostrictive element, and although not shown, the electrostrictive element 20 is similarly subjected to the 8i treatment. 20g is 2
0e and is connected to a lead wire (not shown) below the electrostrictive element, and is connected to the corresponding polarization processing section 20a.
, 20b are also applied with an AC voltage having a phase difference of 90' to generate traveling waves.

Generally, the resonant frequency of this type of motor changes depending on the environmental temperature, etc., so a part of the electrostrictive element is used as a detection part to detect the back electromotive force generated by vibration, so that the imaging wave motor can be driven efficiently at all times. This is controlled by a11.

This back electromotive force is very small, and a very large output impedance is used to accurately load and unload it. For this reason, the electrostrictive element of the detection section 20f is virtually in an electrically open state. On the other hand, the driving polarization processing section 2
The electrostrictive elements 0a and 20b are driven by relatively small human impedance, and under such conditions, that is, if the electrostrictive elements of the detection part are left open, the electrodes will be damaged due to the back electromotive force generated by vibration. A force that is equivalent to being charged with electric charge acts on the electrostrictive element 20 to prevent its own vibration, and the mechanical rigidity of the detection part 20f is isometrically increased compared to other parts.

Alternatively, due to the manufacturing process or various conditions of the electrostrictive element, it is difficult to make the entire electrostrictive element uniform in rigidity, and a difference in rigidity occurs between the polarized parts 20a and 20b, resulting in the following problem.

In other words, there is a phenomenon in which nodes of standing waves tend to form at locations with high rigidity.In other words, if there is a difference in stiffness in the electrostrictive element, the node position of standing waves tends to shift to locations with high rigidity. 1
There was a problem in that the resonant frequencies of the first standing wave and the second standing wave did not match. Therefore, FIG. 4 shows a driving polarization processing section 20a.

20b shows impedance characteristics with respect to each frequency, where A is an impedance characteristic due to a frequency change of the polarization processing section 20a, and B is an impedance characteristic due to a frequency change of the polarization processing section 20b. The lowest impedance points are the resonance points of the respective polarization processing sections 20a and 20b, and the resonance frequency of the polarization processing section 20a is fA, and the resonance frequency of the polarization processing section 20b is f. In other words, due to the non-uniformity of the stiffness of the electrostrictive element, the resonant frequencies of the first standing wave and the second standing wave deviate, and the efficiency of generating the traveling wave by combining the first and second standing waves decreases. There were drawbacks.

<Object of the Invention> The present invention aims to eliminate the above-mentioned drawbacks, and has the purpose of eliminating the above-mentioned drawbacks. An adjustment electrode for adjusting the frequency is provided to adjust the first and second standing waves.

<Example> Fig. 5 shows the electrode configuration of the electro-mechanical energy conversion element applied to the vibration wave motor of the present invention. use.

A progressive vibration wave is generated by applying frequency voltages with a phase difference of 90" to the electrostrictive element group A phase that generates the first standing wave and the electrostrictive element group B phase that generates the second standing wave. is generated.Here, A, -A, and B, -B indicate the insulated A-phase electrode and B-phase electrode, respectively.NA is the first standing wave generated by the A-phase. NB indicates the node position of the second standing wave generated by the B phase.

When the node positions of the first and second standing waves deviate due to non-uniform rigidity of the electrostrictive element 20 or the resonance frequency deviates, the adjustment 7rj, whose pole is C1, is used to create an appropriate standing wave. ~C5
The electrostrictive elements at each electrode location are polarized and insulated, and are left open before adjustment and when adjustment is not required, so that the node positions or resonance frequencies of the A-phase and B-phase standing waves If they are different, the adjustment electrodes C and -C5 are selected as necessary and opened or shorted.

In other words, as described above, the detection unit 2
It is possible to appropriately correct the non-uniformity of the stiffness of the electrostrictive element by charging the electric charge of f or during the manufacturing process. Alternatively, progressive vibration waves can be efficiently generated by aligning the antinode positions or by matching the respective resonance frequencies.

To explain in more detail, the resonance frequency afA of the A-phase standing wave
and the resonant frequency fo of the 8-phase standing wave, that is, fA-
When the difference in f is small, the electrode to be adjusted is the antinode part N of the vibration wave when A-phase vibration is performed. That is, by grounding the electrode C5 or, if necessary, an electrode close to the electrode C3, fA can be lowered and adjusted to substantially match f. Also, fA-
When the 8th difference is small, the electrode to be adjusted is the part of the node of the 1st wave due to A-phase vibration, that is, the electrode C1, or if necessary, if the electrode close to the electric field Ji C+ is grounded, the 6th difference decreases, and f
, it became possible to almost match. Although an electrostrictive element was used in this embodiment, other 61 strain elements or the like may be used in the same manner. Further, the number and shape of the adjustment electrodes are not limited here.

<Effect> As explained above, when the adjustment electrodes are provided on the electrostrictive elements, when there is a large difference in the frequency of the frequency voltage that gives the resonant frequency in each electrostrictive element group (phase A and phase B in the example), the difference in frequency is high. By grounding the adjustment electrode on the side corresponding to the antinode part of the standing wave whose frequency is vibrated, and conversely, when the difference is small, by grounding the adjustment electrode 748i on the side corresponding to the node part, the higher The drive efficiency of the vibration wave motor can be easily improved by lowering the frequency and making it approximately equal to the lower frequency.

Moreover, since the adjustment electrode is grounded, adjustment can be made reliably, and it is possible to provide vibration waves that are resistant to vibration and durability, have a long life, and are highly reliable.

[Brief explanation of drawings]

Figure 1 is an exploded view of the structure of a vibration wave motor. Figure 2 is a diagram of the operating principle of a vibration wave motor. FIG. 3 is a diagram showing the polarization or electrode structure of the electro-mechanical energy conversion element. FIG. 4 is a diagram showing impedance characteristics with respect to frequency of an electro-mechanical energy conversion element. FIG. 5 is a diagram showing the electrode structure of an electro-mechanical energy conversion element provided with the adjustment electrode of the present invention. Patent applicant Canon Co., Ltd. No. 40 Ofe fAFaA* f

Claims (1)

[Claims] A frequency voltage is applied to a plurality of polarized electro-mechanical energy conversion elements to generate a plurality of standing waves, a progressive vibration wave is generated by combining the standing waves, and a moving object is generated by the progressive vibration wave. 1. A vibration wave motor for frictionally driving a vibration wave motor, characterized in that an adjustment electrode is provided to adjust the standing wave.