JPH04181907A - Autofocusing device for camera - Google Patents

Abstract

PURPOSE:To drive a lens and to perform focusing by respectively bonding piezo-electric bodies to the opposite surfaces of a plate-like elastic body, alternately switching both piezo-electric bodies according to a focusing signal so that AC voltage may be impressed and vibrating the elastic body. CONSTITUTION:When the focusing signal is outputted from the focusing signal means of a camera and it shows what is called front focus, for instance, a switching means 16 is switched to a side where a power source part 18 is connected to a 1st piezo-electric body 12a side, and the lens is extended to be normally positioned at a focusing position. In the case that the signal shows what is called rear focus, the means 16 allows the power source part 18 to connect to a 2nd piezo-electric body 12b, on the contrary, and the lens of the camera is receded to be normally positioned at the focusing position. Since longitudinal vibration and bending vibration are made to be generated in the elastic body 10, both of vibration generated in the elastic body is utilized to drive the lens, and the focusing is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic focusing device for a camera that performs a focusing operation using an ultrasonic motor. This relates to a system in which each of the standing waves is generated, and the lens is moved and focused by the driving force generated by the re-vibration.

[Prior Art] Camera autofocus devices that utilize ultrasonic motors are already known.

As this type of ultrasonic motor, one with a traveling waveform is in practical use.On the other hand, with a traveling wave vibrating body, in order to maintain a stable traveling wave, it is necessary to prevent reflected waves from occurring at the end of the vibrating body. It is necessary to In this regard, if the vibrating body is formed into a ring shape, there is no need to consider the termination condition P.A ring-shaped ultrasonic motor is practically used in the automatic focusing device of the camera.

[IR to be Solved by the Invention] However, when such a conventional traveling waveform ultrasonic motor is used in an automatic focusing device of a camera, the appearance of the lens barrel is restricted by the shape of the ultrasonic motor, and ,
Due to the nature of traveling waves, there is a problem with the way the moving body is supported, and it is difficult to increase the efficiency of the motor, resulting in a point B of 7J.

[Object of the Invention] The present invention has been made in view of the problems in the conventional technology, and involves bonding a piezoelectric material to each opposing surface of a flat elastic material, and connecting these four piezoelectric materials using a focusing signal. By alternating switching and applying AC voltage to vibrate, the d9! Cause #M vibration and bending vibration in the sexual body
It is an object of the present invention to provide an automatic focusing device using a string sonic motor that can drive a lens and adjust the focus by utilizing vibrations generated in the elastic body.

No move 8 to decide Jl N! The gist of the present invention to achieve the above object is to detect the distance to a subject and to transmit a high-frequency signal in an autofocus device of a camera equipped with a focus signal means for transmitting a focus signal. The generated power source is connected to the flat elastic body and the cauterizing surface of the elastic body, respectively, and is selectively connected to the self-electrode #J section, thereby generating each of the k1 vibration and bending vibration. A vibrating body section consisting of a first piezoelectric body and a second piezoelectric body that generates a standing wave in the elastic body, and the instantaneous force generated on the surface of the elastic body due to the coupling of the vibrations is extracted by contacting the elastic body. The ultrasonic motor tX is provided with a motion extraction hand and a switching means for selectively connecting the thin part and each of the piezoelectric bodies and switching the direction of motion of the penal station power. As for the vibrating body part of the l1ii wave motor, either one of the motion extracting means F1 is coupled to the immovable part of the camera and the other is connected to the lens drive side, so that it can be switched between forward and reverse directions by the sugosu inch 2 f number Iji. An automatic focusing device for a camera is characterized by:

[Function] With regard to the ultrasonic motor with the above configuration, when a power book is inserted into the first piezoelectric body, the elastic body has wires parallel to the plane.
When longitudinal vibration is excited, bending vibration with a vibration component perpendicular to one plane is also excited. In this case, the mechanical hardness of the first piezoelectric body having an electrically closed layer 1 and the second piezoelectric body having an open layer is different, so that the bending vibration is asymmetrical with respect to the neutral plane. , 11 vibration and the bending vibration, and thus an elliptical vibration is generated which can be converted into a driving force.

Next, if the third piezoelectric body is made into an open layer and electricity is applied to the second piezoelectric body, a reverse elliptical motion will occur.
At this time, the movable body portion pressed against the surface of the first elastic body rotates in the opposite direction.

On the other hand, either the vibrating body of the ultrasonic motor or the motion extracting means 1 is connected to the stationary part of the 4 cameras, and the other of the vibrating body or the motion extracting means is connected to the driving side of the lens. combined.

In addition, each piezoelectric body of the vibrating body! The connection with part # is connected to either one by switching means, and both are simultaneously connected to t! It will not continue.

Now, if the power source is connected to the first piezoelectric body, standing waves of longitudinal vibration and bending vibration induced by this longitudinal vibration are generated in the elastic body of the vibrating body. Then, an elliptical motion occurs in the elastic body that rotates in opposing directions sandwiching the support point that supports it, and this elliptical motion occurs on the surface of the elastic body in a direction that resists each other across the support point. It appears as a driving force that acts on the

Therefore, an instantaneous force in one direction on one side of the support point of the elastic body is transmitted to the motion extraction means that is in contact with the vicinity of one end of the elastic body, and this driving force is ultimately applied to the lens of the camera. An example of movement in the direction 7- is driven to the feeding side.

When the power source is connected to the second piezoelectric body, a driving force in the opposite direction to the above is generated in the elastic body of the vibrating body, and therefore the motion extraction means moves the camera lens in the opposite direction to the above. For example, it acts in the direction of lens contraction.

Therefore, a focusing point signal is now issued from the focusing point signal means of the camera, and in the case of a so-called front bin, for example, the switching means switches to connect the power supply section to the first piezoelectric body side, and the lens is connected to the edge of the lens. and localized to the focal point position.

When the above-mentioned signal is, for example, a so-called rear bin, contrary to the above, the switching means connects the power supply section to the above-mentioned second piezoelectric body side, and the camera lens is retracted and positioned at the focal point position.

[Basic principle of the invention] The operating principle of this invention will be described below.

In this invention, polarized charges are generated on the surface of a piezoelectric body (piezoelectric ceramics) due to mechanical deformation, but at this time, the piezoelectric body is either in an electrically open state 9 (open state) or in a short-circuited state (short-circuited state). There are some methods that take advantage of the fact that the mechanical hardness of piezoelectric materials differs depending on their initial state.

The difference in mechanical hardness between the two manifests as a difference in the speed of sound (the distance of the edge wave). Therefore, when the difference in mechanical hardness between the two is expressed by the speed of sound, the speed of sound is expressed by the first equation since the polarized charge disappears in the electrical state.

On the other hand, in the case of an electrically open state, the polarized charges are not discharged, so the sound speed is expressed by the second equation.

here. C91 is the elastic modulus of the piezoelectric material, e and □ are the piezoelectric constants, and C3 is the dielectric constant of the piezoelectric material.

FIG. 1 is a diagram showing the basic configuration P of an ultrasonic vibrating device of the present invention, which uses the above-mentioned electromechanical properties of a piezoelectric material to electrically obtain asymmetry. In this figure, reference numeral 4 indicates a plate-shaped elastic body made of metal. 5a and 5b are plate-shaped piezoelectric bodies (piezoelectric ceramics) polarized in the thickness direction, one (5a) is bonded to the upper surface of the elastic body 4, and the other (5b) is bonded to the lower surface, facing each other. There is. 6a is a t-pole formed on the upper surface of the piezoelectric body 5a. Reference numeral 7 denotes an excitation power source that outputs a high frequency voltage at the longitudinal vibration resonance frequency of the elastic body 4. One terminal of this power source 7 is electrically connected to the elastic body 4, and the other terminal is electrically connected to the electrode 6a. There is.

The elastic body 4 has a symmetrical cross-sectional shape with respect to the neutral plane N of bending vibration, and is formed so that the longitudinal vibration resonance frequency and the bending vibration resonance frequency match or approach each other.

Here, C31 is the elastic modulus of the piezoelectric material, eel is the piezoelectric constant, and C3 is the dielectric constant of the piezoelectric material.

FIG. 1 is a diagram showing the basic configuration of an ultrasonic vibration device of the present invention, which uses the electromechanical properties of a piezoelectric material to electrically obtain asymmetry. In this figure, reference numeral 4 indicates a plate-shaped elastic body made of metal. 5m and 5b are plate-shaped piezoelectric materials (piezoelectric ceramics) polarized in the thickness direction, and one (5a) is attached to the upper surface of the elastic body 4, and the other (5b) is attached to the lower surface, facing each other. has been done. 6m is a t-pole formed on the upper surface of the piezoelectric body 5a. 7 is an excitation power source that outputs a high frequency voltage at the longitudinal vibration resonance frequency of the elastic body 4; one terminal of this power source 7 is connected to the elastic body 4, and the other terminal is connected to the elastic body 4! [! 6a, respectively.

The elastic body 4 has a symmetrical cross-sectional shape with respect to the neutral plane N of bending vibration, and is formed so that the longitudinal vibration resonance frequency and the bending vibration resonance frequency match or approach each other.

Generally, the resonance frequency 1'L of a plate-shaped elastic body is expressed as in the third equation.

Here, E is the Young's modulus of the elastic body, ρ is its density, and 1 is its length.

On the other hand, the resonance frequency IB of bending vibration on the surface of a plate-shaped elastic body is expressed as in the fourth equation.

Here, glue is the width of the elastic body, and shi is its thickness.

Further, α is the root of Equation 5, and corresponds to the order of the resonance mode of the symmetrical bending vibration from the smallest order.

From the above, when ft = fB, that is, if the length l, width, and thickness t of the elastic body satisfy the relationship of Equation 6, the vibration mode of longitudinal vibration and the vibration mode of bending vibration coexist, and as mentioned above, Elliptical vibration is generated on the surface of the elastic body. In this case, it is possible to freely select any two of the three variables: length 1, width - 1 thickness t.

In the above purification, the piezoelectric body 5a receives a power source 7f! : When it is turned on, longitudinal vibration parallel to the plane is excited in the elastic body 4. When longitudinal vibration is excited, bending vibration, which has a vibration component perpendicular to the surface, is also excited! do. In this case, the piezoelectric body 5a in the electrically open state and the piezoelectric body 5b in the shorted state have different mechanical hardnesses, so the elastic body 4 becomes unsymmetrical with respect to the neutral plane of bending vibration. Therefore, the longitudinal vibration and the bending vibration are combined, thus producing an elliptical vibration that can be converted into a driving force.

Practical Example Hereinafter, a practical example of the present invention will be explained with reference to the drawings.

First, the ultrasonic motor that is the driving source will be explained.

FIG. 2 is a sectional view for explaining the driving principle of the ultrasonic motor according to the present invention, and FIG. 3 is a perspective view thereof. In this drawing, reference numeral 10 denotes a plate-shaped elastic body made of a metal material such as stainless steel or aluminum, and piezoelectric bodies (piezoelectric vibrators N, 2M, and 12b are arranged facing each other on both sides of the elastic body 10). The elastic body 10 and the piezoelectric bodies 12a and 12b substantially constitute the vibrating body part of the ultrasonic drive device.Of both sides of the piezoelectric bodies 12g and 12b, at least the elastic body A conductive layer (not shown) is formed on the surface not in contact with the piezoelectric body 12a,
One end of the electrical line 14m, 14b is connected to the surface of each of the two planes of the electrical line 12b that is not in contact with the elastic body 10, and the other end of the electrical line 14m, 14b is connected to the electrical line 14m, 14b. They are connected to terminals 16m and 16b, respectively. One end of an electric line 14c is connected to the elastic body 10, and the other end is connected to a single-phase power source 1 for excitation.
8 is connected. Moreover, the piezoelectric body 12 of the elastic body 10
A motion extracting body 20 is disposed on the side where a is provided so as to be in direct contact with the elastic body 10.

The elastic body 10 has a convex portion 11 extending from the center in the length direction of the elastic body 10, and a fixing screw 15 can be passed through a hole 13 provided in the convex portion 11 to attach a frame member (not shown). is fixedly supported. The above-mentioned convex all is the order 1 of the node generated from resonance of longitudinal vibration determined by the length of the elastic body 10.
is set to . Furthermore, in this example, the elastic body 10 has a resonance frequency of longitudinal vibration generated in the length direction of the elastic body 10 while being fixed to the frame member,
It is formed to have a shape (length, width, and thickness) that substantially matches the resonance frequency of bending vibration occurring in the width direction. In the piezoelectric bodies 12a, 12b, a node of longitudinal vibration generated at the midpoint in the longitudinal direction of the elastic body 10 is
b is arranged on the elastic body 10 so as to be located approximately at the center in the length direction.

The sheep phase power supply 18 is a power supply for supplying a high frequency voltage having the same frequency as the longitudinal vibration resonance frequency of the elastic body 10 to the piezoelectric bodies 12a and 12b, and the switch mechanism 16 is configured to:
The switch 16c is an electrical switching means for selectively applying the high frequency voltage output from the source 18 to the voltage bodies 12a and 12b by the switching operation of the switch 16c.

The motion extracting body 20 is a rotatable roller-like member that is positioned on the elastic body 10 by an arbitrary means, and is pressed against the elastic body 10 by an arbitrary pressure means.

Next, referring to FIG. 4, the operation of the ultrasonic driving device having the above-mentioned refinement will be explained.

FIG. 4 shows an elastic body 10 formed in a size and shape in which longitudinal vibration in vibration mode L, (one node) and bending vibration in vibration mode BtO (two nodes) occur in the same way due to resonance. Although not shown, protrusions are provided on both sides corresponding to the node positions of the vibration mode L1o, and these protrusions are fixedly supported by a frame member (not shown). There is.

In the vibrating body section shown in the figure, for example, the piezoelectric body 12a
Turn on the power to the piezoelectric body 12a (predetermined wIS
When excited (at a dynamic resonance frequency), a longitudinal vibration mode LIO is generated in the length direction of the elastic body 10, and a bending vibration mode B2 is generated in the width direction in resonance with the longitudinal vibration.
゜ is induced. And, due to the combination of these re-vibrations,
Elliptical vibration is generated on the surface of the elastic body 10. In this example, since the vibration mode of the bending vibration is B2°, the center part 1
The rotational directions of the elliptical vibration at °C and the elliptical vibration at both ends 10s are opposite to each other. At this time, for example, if the motion extracting body 20 is configured to contact only the central part 10c of the elastic body, the driving force in a certain direction can be extracted. When a t source is applied to the body 12b, the piezoelectric body 12b is excited, and along with this excitation, a vibration mode L1° of longitudinal vibration is generated in the length direction of the elastic body 10, and a vibration mode L1° is generated in the width direction of the elastic body 10. Vibration mode B2 of bending vibration in resonance with the above longitudinal vibration
゜ is induced. In this example, piezoelectric bodies 12m, 1
2b, longitudinal vibrations in the same phase (longitudinal vibrations in the same phase for deformation in the same direction) are generated, but the phases of the bending vibrations differ by 180 degrees from each other depending on which of the piezoelectric bodies 12a and 12b is excited. It will be 16 times different. Therefore, when exciting the piezoelectric body 12m, the elliptical vibration generated on the surface of the elastic body 10 rotates in the direction shown by the solid line arrow in FIGS. 2 and 3, and therefore the motion extracting body 2
The direction of the motion (driving force) taken out by 0 is also the direction shown by the solid line arrow in the same figure. Next, when switching to the excitation of the piezoelectric body 12b, the elliptical vibration generated on the surface of the elastic body 10 is, for example, The direction is reversed in the direction shown by the dashed arrow in the figure, and therefore the motion (driving force) extracted by the motion extractor 20 is also reversed in the direction shown by the broken line arrow in the figure.

Note that if the driving force of the elliptical vibration is broken down into components, a levitation force is applied to the motion extracting body 20 due to the bending vibration, and a driving force is applied to the motion extracting body 20 due to the longitudinal vibration.

According to the above configuration, the card-like member is placed on the motion extracting body 2o,
If the conveyed object such as paper products comes into contact with the switch 16c,
By switching, the object can be transferred in any direction.

Further, since the convex portion 11 fixedly supported by the frame member is provided at the position of the node of longitudinal vibration, it is possible to prevent the longitudinal vibration from being attenuated due to the fixed support of the elastic body 10.

Furthermore, since the vibration mode of the bending vibration is generated in the width direction of the elastic body 10, even when the node position 1 of the longitudinal vibration is fixed by the frame member, the elastic body 10
At both ends in the length direction, the generation of the vibration mode of bending vibration is not suppressed.

Therefore, highly efficient driving force with excellent responsiveness can be obtained.

Fig. 5 (1), (b), and (c) are diagrams showing the configuration of the main parts as an ultrasonic motor. Each is a partial sectional view. In these figures, parts corresponding to those shown in FIGS. 2 and 3 are given the same reference numerals, and their explanations will be omitted. In this example, the elastic body 10 has dimensions of, for example, 27.3 [+sm] x 1 [ms+] x 8
A [m+e] 5US420 (stainless steel) plate is used, and piezoelectric bodies 1.2m and 1.2b are pasted on the opposing planes of the elastic body 10, respectively, as in the first practical armpit example. These piezoelectric bodies 12m, ] 2b have dimensions of, for example, 15[@II]X 0 , 5[-1]X8[
The elastic body 10, which uses a PZT (zirconate titanate) plate, has a convex portion 1 extending from approximately the center thereof.
1.11, it is fixedly supported by the frame member 30. A pair of arms 36m and 36b are provided along both sides of the frame member 3o, and these arms 36
a and 36b are shafts 3 provided at one end of the frame member 30;
4, one end of each is rotatably supported. The other ends of the arms 36a, 36b are connected via a spring support member 38, so that the pair of arms 361, 36b can rotate integrally. Further, a motion extractor support shaft 40 that rotatably supports the roller-shaped motion extractor 20 is passed through the intermediate portion of each of the arms 36m and 36b.

As shown in FIG. 5, the motion extractor 20 is disposed approximately in the center of the elastic body 10 in the radial direction and near the end in the length direction. The pressure spring 42 is tensioned by having one end locked to the end surface of the frame member 30 and the other end locked to the spring support member 38 in order to keep the motion extraction body 20 in pressure contact with the elastic body 10 at all times. ing.

In this second embodiment, a single-phase power supply, a switch mechanism, etc. having the same configuration as in the first embodiment are used as appropriate, but these are omitted in FIG. 5 for brevity.

In the above configuration, when the single-phase power supply is turned on, the frequency of 98
KHz high frequency voltage is the best in Switzerland and Sochi! The voltage is applied to the piezoelectric body 12@ or 12b via the ellipse. As a result, the piezoelectric body 12m or 12b is excited, and a vibration mode L of longitudinal vibration is generated on the elastic body 10. and vibration mode B of bending vibration.

These generated re-vibrations combine with each other, and this combination causes an elliptical motion. movement extractor 2
0 extracts the driving force from the generated elliptical motion, and the extracted driving force is transmitted to the pulley 44.

FIG. 5(d) is a graph showing the measured values of the torque knee rotation speed N characteristics transmitted to the pulley 44 by the ultrasonic drive device of this example.As shown in the figure, when a voltage of IIV is applied , torque [T] and rotation speed [N] are maximum torque 15 [gc-1, no-load rotation speed 600 [rps
]was gotten.

FIG. 6 also shows the main components of an ultrasonic motor A that receives a subject distance signal from a focusing point signal means E, drives the focusing ring C, and automatically performs focusing operation by extending or retracting the lens unit B. The part is disassembled and shown.
FIGS. 7 and 8 are diagrams showing the assembled state seen from the front and back.

The ultrasonic motor A has a frame 30a and a frame 30b, and both frames are connected by connecting rods 41a and 41b.

Both frames 30a and 30b are provided with plates 31a and 31b for attaching the elastic bodies, respectively.
However, at the support point 11, the above-mentioned attachment is fixed to the plates 31a, 31b.

First and second piezoelectric bodies 12a and 12b, each having the same width and short length, are attached to both sides of the elastic body 10, respectively.

As shown in FIGS. 6 and 8, a pickup roller 20, which is a motion extractor, is in rotatable contact with the elastic body 10 via a shaft 40. As shown in FIGS. A first transmission gear 31 is fixed to the shaft 40. The L shaft 40 is pivotally supported by a pressing member 36 for pressing the pickup roller 20 against the elastic body 10, as shown in FIG. This pressing member 36 is pulled by a pressing force adjusting bolt 44 screwed into the bent portion 32 of the frame 31a and a pressing spring 42 stretched between the bent portion 32 of the pressing member 44, Elastic body 1 of the pickup roller 20
The contact force relative to 0 can be adjusted.

A second transmission gear 32 supported by a shaft 37 meshes with the first transmission gear 31 . This shaft 37 is pivotally supported in a shaft hole 36a of the pressure contact member 36, and is also pivotally supported by both frames 30a and 30b through the shaft hole 36a. A pickup roller 20 is pressed against the elastic body 10.

Further, a third transmission gear 34 is press-fitted into a shaft 39 that is pivotally supported by both frames 30a and 30b, and meshes with the second transmission gear 32, and an output gear 33 is fixed to the same shaft. 33 meshes with the internal gear C1 of the focus ring C of the camera, as shown in FIG.

FIG. 9 shows a block diagram of the entire autofocus device of the camera.

FIG. 10 shows a front perspective view of camera G equipped with the automatic focusing device of the present invention.

The camera G has a lens unit B attached to the front part of the camera body so that the focus can be adjusted by a focus ring C, and the focus ring C automatically focuses by the action of the automatic focus device configured as shown in section 9 above. It is adjustable and can also be adjusted manually from the outside.

The focused point signal means E includes a first light receiving element E1 and a second light receiving element E2, which are composed of a CCD or the like and are arranged with an interval of the base line length, and the light receiving element E1. A first lens E3 and a second lens E4 for directing reflected light from the subject to E2.
and a signal processing circuit E5 which compares the data captured by each of the light receiving elements E1 and E2 and determines whether it is a front bin or a rear bin.

This in-focus point signal means E is configured such that in an in-focus state, the difference in output data between the first light-receiving element E1 and the second light-receiving element E2 is 0, and in a front-bin state, the difference in output data is sufficient. In addition, the signal processing circuit E5 is adjusted in advance so that the difference in output data changes to - in the rear bin state.

That is, the in-focus point signal means E outputs an inverted output to the ultrasonic motor drive circuit shown in section 11 depending on whether the front focus or the rear bin is in focus.

Figure 11 shows the ultrasonic motor drive circuit.
H according to the output from the previous focused point signal means E to the CCW terminal.
One of the step-up transformer T1 and the step-up transformer T2 is boosted by being inverted controlled to either the level or the L level,
The elastic body 10 is excited by applying a voltage to one of the corresponding piezoelectric bodies 12a or 12b. Then, depending on the excitation state of the elastic body 10, the motion extracting body 20
rotates to drive lens unit B and adjust focus.

[Effects of the Invention] As described above, the present invention involves bonding a piezoelectric body to each opposing surface of a flat elastic body, and then alternately switching the piezoelectric body using a focusing point signal and applying an alternating current voltage to vibrate the piezoelectric body. Since longitudinal vibration and bending vibration are generated in the elastic body, an automatic focusing device driven by an ultrasonic motor is capable of driving the lens and adjusting the focusing point by utilizing the re-vibration generated in the elastic body. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic configuration of an ultrasonic motor according to the present invention, Fig. 2 is a cross-sectional view for explaining the driving principle of the ultrasonic motor, Fig. 3 is a perspective view of the same, and Fig. 4 is A diagram for explaining the operation of the ultrasonic motor according to the invention, FIG. 5(a)
is a diagram showing the main part configuration of the ultrasonic motor in Figure 2, Figures 5(b) and (C) are the same cross-sectional views, and Figure 5(d) is the experimental value of the torque-rotation speed characteristic of the same device. 6 is an overall exploded perspective view of the ultrasonic motor shown in FIGS. 2 to 5, and FIGS. 7 and 8 are assembled perspective views of the ultrasonic motor shown in FIG. FIG. 9 is a block diagram of an automatic focusing device of a camera, FIG. 10 is a perspective view of a camera equipped with the automatic focusing device of the invention, and FIG. 11 is a driving circuit diagram of an ultrasonic motor according to the invention. A. Ultrasonic motor, 10. Vibrating body, 12a 12b. Piezoelectric body, 16...Switching means 20..Motion extraction means, E. Focusing point signal means. (No change in content) Engraving of the drawing on page 5 of Figure 4 (No change in content) Engraving of the drawing in Figure 5 (d) (No change in content) Houkiq diagram procedural support device (method) March 1991 14th 1, Indication of the case Patent application No. 2-312352 2, Title of the invention Camera autofocus device 3, person making corrections Relationship to the case Patent application Human body Location 430-14 Kobayashi, Masuho-cho, Minamikoma-gun, Yamanashi Prefecture , Date of amendment order (shipment date) ゞ -゛February 1, 1991
2nd day 5, drawings subject to correction 6, interior room to be corrected

Claims (1)

[Claims of Claims] An automatic focusing device for a camera equipped with a focus signal means for detecting the distance to a subject and transmitting a focus signal, comprising: a power supply section that generates a high-frequency AC voltage; and a flat elastic body. and a first piezoelectric material which is respectively joined to opposing surfaces of the elastic body and selectively connected to the power supply section to generate standing waves of longitudinal vibration and bending vibration in the elastic body. a vibrating body section made of two piezoelectric bodies, a motion extracting means for contacting the elastic body and extracting a driving force generated on the surface of the elastic body due to the coupling of the vibrations, the power supply section and each of the piezoelectric bodies; an ultrasonic motor provided with a switching means that is selectively connected to switch the direction of movement of the driving force, and either the vibrating body portion of the ultrasonic motor or the motion extracting means is connected to a camera. An automatic focusing device for a camera, characterized in that one of the fixed parts is coupled to a lens driving side, and the switching means is switched between forward and reverse directions according to the focusing signal of the camera.