JPH04211210A - Lens barrel by use of vibrating motor - Google Patents

Abstract

PURPOSE:To reduce torque loss caused by a load of energizing force by a spring member. CONSTITUTION:A cylindrical fixed barrel 24, a bearing 25 arranged in an inner diameter position of the fixed barrel 24 and a stator 2 are provided, and a vibrating motor to rotate a rotary body 21, which is energized springily in the optical axial direction against the stator 2 by means of a spring member 22, around the optical axis by means of vibration of the stator 2 and a movable lens 20 are also provided. Furthermore, the rotary body 21 and a rotary bearing object 27 for a bearing 25 are brought into contact with each other in the optical axial direction, and the movable lens 20 is moved in the optical axial direction by rotating the rotary body 21 by means of a lens delivery mechanism, and a receiver of energizing force by the spring member 22 in the vibrating motor in the optical axial direction is carried out by means of a fixing member 23 through the rotary bearing object 27.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel using a vibration wave motor that utilizes mechanical vibration.

0002

[Prior Art] Vibration motors have already been developed in Japanese Patent Application Laid-open No. 52-291.
As is known from Japanese Patent No. 92, etc., a fixed body and a movable body are brought into frictional contact, and at least one of them is constituted by an electro-mechanical energy conversion element itself or an elastic vibrating body including an electro-mechanical energy conversion element. By applying alternating current electrical energy to the electro-mechanical energy conversion element, mechanical vibration energy is generated, and the movable body is frictionally driven in one direction.

0003

[Problems to be Solved by the Invention] Conventionally, attempts have been made to apply a vibration motor to driving a lens, but the following problems have been encountered. In other words, the vibration motor is provided with a spring member so that the stator and the rotating body come into strong frictional contact, but the biasing force of this spring member becomes a large load, making it difficult to drive the lens smoothly. .

An object of the present invention is to provide a lens barrel using a vibration motor that can reduce torque loss due to the load of the biasing force of a spring member.

[0005]

[Means for Solving the Problems] The present invention has a cylindrical fixed cylinder, a bearing disposed at an inner diameter position of the fixed cylinder, and a stator, and a spring member is applied to the stator in the optical axis direction. A vibration motor that rotates a rotating body, which is spring-biased by a spring, around the optical axis by the vibration of the stator, and a movable lens, the rotating body and the rotating body for the bearing of the bearing are brought into contact in the optical axis direction, and the lens The movable lens is moved in the optical axis direction by the rotation of the rotating body by the feeding mechanism, and the fixed member receives the biasing force of the spring member in the vibration motor in the optical axis direction via a rotating bearing such as a ball or roller. As a result, the load of the urging force of the spring member is applied to the bearing rotating object, and the torque loss due to the load is reduced to a level where it is not affected.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining a lens barrel as an embodiment of the present invention, an example of a vibration motor will be explained with reference to FIG.

In FIG. 1, 1 is a moving body (rotating body) pressurized by a force F, 2 is a fixed body (stator) that vibrates elastically using an electrostrictive element, and the x-axis is set on the surface of the fixed body 2. , and the z-axis is its normal direction. Fixed body 2 by electrostrictive element
When bending vibration is applied to the surface of the fixed body 2, a traveling vibration wave is generated and propagates on the surface of the fixed body 2. This traveling vibrational wave is a surface wave accompanied by longitudinal waves and transverse waves, and the motion of its mass point follows an elliptical orbit. Focusing on the mass point A, it is performing an elliptical motion with a longitudinal amplitude u and a lateral amplitude w, and if the traveling direction of the surface wave is the x-axis direction, the elliptical motion is counterclockwise. This surface wave has apex A, A'... for each wavelength, and the apex velocity is x
component only, and v=2πfu (f is the frequency). Therefore, when the surface of the movable body 1 is brought into frictional contact with the surface of the fixed body 2, the surface of the movable body 1 contacts only the vertices A, A', etc., so the movable body 1 is driven in the direction of the arrow N by the frictional force. be done.

The speed of the moving body 1 is proportional to the frequency f. Furthermore, due to frictional drive due to pressurized contact, it depends not only on the longitudinal amplitude u but also on the transverse amplitude w. That is, the speed of the moving body 1 is proportional to the magnitude of the elliptical motion. Therefore, moving body 1
The speed of is proportional to the voltage applied to the electrostrictive element.

FIG. 2 is an exploded view showing the configuration of an example of a vibration motor. Hard rubber 1a is adhered to the annular moving body 1 to facilitate frictional contact. Electrostrictive elements 3 a and 3 b forming two groups are bonded to the annular fixed body 2 . When the electrostrictive elements 3a and 3b operate independently, they are arranged in a state where the fixed body 2 resonates, that is, in a position where a standing vibration wave exists, and the electrostrictive elements 3a and 3b are arranged in a position where the standing vibration wavelength is They are arranged so that the wavelength of the standing vibration caused by the electrostrictive element 3b is equal to each other, and the phase is shifted by 90 degrees (the physical position is shifted by 1 wavelength/4). The felt 4 absorbs vibrations on the surface of the fixed body 2 opposite to the frictional contact surface. The support body 5 supports the fixed body 2, the electrostrictive elements 3a and 3b, and the felt 4.

FIG. 3 is a diagram illustrating the generation of traveling vibration waves and standing vibration waves. For the sake of explanation, the electrostrictive elements 3a and 3b are not arranged as shown in FIG. 2 but are arranged alternately, but they satisfy the same conditions as above and are equivalent arrangements. The driving power source 6 supplies a voltage of V=Vosin ωt. A voltage Vo sin ωt is directly applied to the electrostrictive element 3a from the drive power source 6 through a line 7, and the electrostrictive element 3b
The voltage Vo s is applied via line 9 through 90° phase shifter 8.
in(ωt ±π/2) is applied. VoltageVos
The ± of in(ωt ±π/2) can be switched depending on the direction in which the moving body 1 is moved. A to F in Fig. 3 are voltages Vo s
The state of the vibration wave when in(ωt −π/2) is applied is shown. A shows a state in which a standing vibration wave 10 is generated only by the electrostrictive element 3a, and B shows a state in which a standing vibration wave 11 with a 90° phase delay is generated only by the electrostrictive element 3b. H~N are two electrostrictive elements 3
It shows a state in which traveling vibration waves 12 are generated by operating a and 3b simultaneously. C is time t=0+2nπ/ω, D is time t=π/2ω+2nπ/ω, and E is time t=π/ω.
+2nπ/ω and F indicate the phase of the traveling vibration wave 12 of 3π/2ω+2nπ/ω, respectively. The traveling vibration wave 12 travels to the right in FIG. 3, but any mass point on the frictional contact surface of the fixed body 2 performs an elliptical motion in a counterclockwise direction. Therefore, the moving body 1 moves to the left.

In the state in which the standing vibration waves 10 and 11 of A and B are generated, the mass points other than the nodes on the frictional contact surface of the fixed body 2 exhibit only transverse vibration, that is, vertical movement in FIG. 3. Therefore, the frictional contact between the movable body 1 and the fixed body 2 is not a static friction state but a dynamic friction state, and the friction coefficient is small and the contact area is also small. Therefore, when moving the movable body 1 manually, it can be moved with a small force.

FIG. 4 shows the structure of a lens barrel according to an embodiment of the present invention. Components similar to those in FIG. 2 are designated by the same reference numerals.

At the rear end of the fixed barrel 13 of the lens barrel, a mounting member 14 such as a bayonet or screw mount for mounting on the camera is provided. A straight groove 13a is provided in the fixed barrel 13 in the optical axis direction. lens holding cylinder 15,
Reference numeral 16 holds a lens optical system 17 that is fitted inside the fixed barrel 13 and performs a magnification change function and a correction function for aberrations accompanying the magnification change. Each lens holding cylinder 15, 16 has pins 15a, 16.
a is planted, and these pins 15a and 16a are inserted into the straight groove 1.
The cam cylinder 1 penetrates through 3a and is fitted on the outer periphery of the fixed cylinder 13.
It fits into the cam grooves 18a and 18b of No.8. Lens holding tube 1
Reference numeral 9 holds the focusing lens optical system 20, and has a threaded portion 19a on the outer periphery to be screwed into the lens holding barrel 15. The cylindrical collar portion 19b is fitted into a rectilinear groove 21a formed in the inner peripheral surface of the distance adjustment ring 21 as a rotating body in parallel to the optical axis direction. A grip portion 21b is provided at the tip of the distance adjustment ring 21. The friction contact portion 21c of the distance adjustment ring 21 corresponds to the movable body 1 in FIG. 2, and is pressed against the fixed body 2 (stator) by a ring leaf spring 22. The fixed base cylinder 23 is integrally fixed to the fixed cylinder 13 with screws (not shown), and supports the fixed body 2, the electrostrictive elements 3a and 3b, and the felt 4.

An outer cylinder 24 serving as a fixed cylinder is screwed to the base cylinder 23, and a first ring 25 and a second ring 26 for bearings are attached to the inside of the outer cylinder 24. That is, the first ring 25 is pressed against the friction contact portion 21c of the distance adjustment ring 21 by the ring leaf spring 22 via the bearing ball 27 as a rotating object for the bearing. The second ring 26 is attached by being screwed into the inner peripheral surface of the outer cylinder 24, but the first ring 25 and the second ring
A V-shaped circumferential groove is formed at the joint with the ring 26,
This circumferential groove and the approximately U formed on the outer peripheral surface of the distance adjustment ring 21
A bearing ball 28 is held between the groove and the circumferential groove. Thereby, the distance adjustment ring 21 is rotatably attached to the outer cylinder 24, and rotatable frictional contact of the frictional contact portion 21c with the fixed body 2 is ensured.

The biasing force of the ring plate spring 22 in the optical axis direction is received on one side by the outer cylinder 24 as a fixed cylinder, and on the other side by the base cylinder 23 as a fixed member via a bearing ball 27. I decided to accept it. As a result, the torque loss of the distance adjustment ring 21 due to the biasing force of the ring plate spring 22 is extremely reduced due to the spherical and rotatable bearing ball 27, and is essentially not a problem.

The code plate 29 has comb-like electrodes, is attached to the inner wall surface of the outer cylinder 24, and is connected to the distance adjustment ring 21.
When the slider 30 fixed to the slider 30 slides on the comb-shaped electrode, a movement amount monitor signal is generated which is made up of a number of pulses corresponding to the amount of rotation of the distance adjustment ring 21, that is, the amount of movement of the focusing lens optical system 20. occurs. An electric manual changeover switch 31 is provided on the outer cylinder 24, and its contact piece 32 is attached on the base cylinder 23. The operation pin 33 is attached to the cam barrel 18, and rotates the cam barrel 18 by turning it around the optical axis from the outside of the base barrel 23. When the cam cylinder 18 rotates, the cam grooves 18a and 18b move the pins 15a and 16a along the straight groove 13a, so the lens holding cylinders 15 and 16 move in the optical axis direction, and perform the zooming action and the aberration correction action. I do.

FIG. 5 shows a circuit of one embodiment of the present invention. The autofocus light receiver 34 is connected to the distance measuring circuit 35 using, for example, a charge-coupled device. Output terminal A of the distance measuring circuit 35 outputs a high-level drive signal or a low-level stop signal to the vibration wave motor, and output terminal B outputs a high-level near-side drive direction signal or a low-level infinity-side drive signal. A direction signal is output, and an electric manual switching circuit 36 is connected to the input terminal C.
A switching signal is inputted to the input terminal D via the inverter 37, and a movement amount monitor signal is inputted to the input terminal D from the monitor signal generation circuit 38 via the chattering absorption circuit 39. The electric manual changeover circuit 36 includes an electric manual changeover switch 31 and a resistor 40.
The monitor signal generating circuit 38 consists of a code plate 29, a slider 30, and a resistor 41. The pulse generation circuit 42 includes an oscillator 43, frequency dividers 44, 45 with a frequency division ratio of 1/2, and an inverter 46, and outputs pulses having a phase difference of 90 degrees from the frequency dividers 44, 45. 47 is an OR gate, 48 is an AND gate, and 49 is an exclusive OR gate. The exclusive OR gate 49 assumes that the phase of the pulse of the frequency divider 45 is advanced by 90 degrees with respect to the pulse of the frequency divider 44 when the input from the output terminal B of the distance measuring circuit 35 is at a high level, and by 90 degrees when the input is at a low level. ° It is considered late.

The drive control circuit 50 is a circuit for controlling the drive of the electrostrictive elements 3a and 3b, and is composed of two push-pull circuits 51 and 52 made up of transistors, resistors, and inverters, switching transistors 53 and 54, and the like. The switching transistors 53 and 54 are connected to a power source via a resistor 55 and a lens drive power switch (not shown).

Next, the operation of the embodiment shown in FIGS. 4 and 5 will be explained. When the lens drive power switch (not shown) is turned on, power is supplied to the electric manual switching circuit 36, inverter 37, OR gate 47, AND gate 48, exclusive OR gate 49, pulse generation circuit 42, and drive control circuit 50, and the pulse generation circuit 42 and drive control circuit 50 are supplied with power. The generating circuit 42 starts operating.

[0020] When the electric manual changeover switch 31 is turned off,
When electric drive is selected, electric manual switching circuit 36
Since outputs a high level switching signal, AND gate 48 is opened. Also, this switching signal is applied to the inverter 37.
The signal is inverted at , becomes low level, and is input to the input terminal C of the distance measuring circuit 35 .

When the first stroke of the release button, which consists of two strokes, is pressed for photographing operation of the camera, a photometric calculation operation is started. The distance measuring circuit 35 determines that it is electrically driven by inputting a low-level switching signal to the input terminal C, starts automatic focusing operation, and sets the focusing range to a narrow width for automatic focusing. Light receiver 34
receives the reflected light from the subject, and the distance measuring circuit 35 detects the focusing error based on the subject information from the light receiver 34 based on a known contrast detection method, shift detection method, etc., and determines the lens drive amount and drive direction. calculate. The lens drive amount is preset in a counter (not shown) in the distance measuring circuit 35. A high level drive signal is output from output terminal A,
Assuming that the subject is on the near side, output terminal B outputs a high level near side drive direction signal. Therefore, the OR gate 47 and the AND gate 48 both output high level signals, and the switching transistors 53 and 5
Turn on 4. Therefore, the push-pull circuit 51,
Power is supplied to 52. The pulse generation circuit 42 is in operation, and the pulses from the frequency divider 44 are directly transmitted to the push-pull circuit 5.
2, high frequency power is applied to the electrostrictive element 3b. The pulses of frequency divider 45 are inverted by exclusive-OR gate 49 to 90° to the pulses of frequency divider 44.
Since the phase is advanced and the push-pull circuit 51 is controlled, high frequency power with a 90° phase advance is applied to the electrostrictive element 3a. As a result, a traveling vibration wave 1 is generated in the fixed body 2.
2 occurs, and the distance adjustment ring 21 is rotated in the focusing direction. Along with this, the lens holding cylinder 19 rotates while being screwed together with the lens holding cylinder 15, so that it moves in the drawing direction and reaches the in-focus area.

By rotating the distance adjustment ring 21, the slider 3
0 slides on the code plate 29 and generates a movement amount monitor signal of the number of pulses corresponding to the movement amount of the lens. This movement amount monitor signal is input to the input terminal D of the distance measuring circuit 35, and causes the counter to subtract the preset lens drive amount. When the value of the counter reaches zero, a low level stop signal is output from output terminal A, and OR gate 47 and AND gate 4
Since the output of 8 is inverted to low level, the switching transistors 53 and 54 are turned off, and the electrostrictive elements 3a and 3
b is cut off from the power source, and the driving of the distance adjustment ring 21 is stopped. Here again, distance measurement is performed by the light receiver 34 and the distance measuring circuit 35, and if the focusing error is within the in-focus range,
Indicates focus. When the lens is not in the in-focus area, the lens is driven again in the same manner as described above.

When the subject is on the infinity side, the output terminal B of the distance measuring circuit 35 outputs a low-level infinity side drive direction signal, so the exclusive OR gate 49 is connected to the frequency divider 45.
It is assumed that the pulse is passed through as is and its phase is delayed by 90 degrees from the pulse of the frequency divider 44. Therefore, the electrostrictive elements 3a and 3b generate traveling vibration waves traveling in opposite directions, and the distance adjustment ring 21
rotates in the opposite direction to move the lens holding cylinder 19 in the retracting direction.

[0024] When the electric manual changeover switch 31 is turned on,
When manual drive is selected, the electric manual switching circuit 36
outputs a low level switching signal, so OR gate 4
The output of 7 becomes high level, turning on the switching transistor 54. On the other hand, the output of the AND gate 48 becomes low level, turning off the switching transistor 53. Therefore, high frequency power is not supplied to the electrostrictive element 3b, but only to the electrostrictive element 3a. Therefore, a standing vibration wave 10 is generated in the fixed body 2, and the friction torque between the fixed body 2 and the distance adjustment ring 21 is reduced. Therefore, by holding the grip portion 21b slightly exposed from the tip of the outer cylinder 24 and turning the distance adjustment ring 21, the lens holding cylinder 19 is moved in the optical axis direction by turning the distance adjusting ring 21 lightly with a small manual torque.

The distance measuring circuit 35 determines that manual drive is being performed by inputting a high-level switching signal to the input terminal C, sets the width of a wide focusing range for manual driving, and sets the width of a wide focusing range for manual driving. When the lens optical system 20 reaches its in-focus area, in-focus display is performed.

In the embodiment described above, only the focusing lens optical system 20 is moved by the vibration motor, but the zooming lens optical system (17, 20) may also be moved.

[0027]

Effects of the Invention The lens barrel using the vibration motor of the present invention was able to reduce torque loss when driving the movable lens using the vibration motor as the drive source. The first feature is that a bearing using a rotating bearing is installed in the rotation transmission system generated by the output of the vibration motor, which significantly reduces torque loss compared to a normal fitting type receiver. be able to. The second feature is that torque loss due to the biasing force of the spring member (used to bring the stator into frictional contact with the driven member at an appropriate pressure) in the vibration motor is suppressed; The force is received through the above-mentioned rotary bearing, which can disperse stress and reduce torque loss by rotating, so that there is virtually no influence, making it possible to put a lens barrel incorporating a vibration motor into practical use. It made it possible to

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the driving principle of a vibration motor as an example.

FIG. 2 is an exploded view showing the basic configuration of a vibration motor as an example.

3 is a diagram illustrating the generation of traveling vibration waves and standing vibration waves in the vibration motor shown in FIG. 2. FIG.

FIG. 4 is a sectional view showing an embodiment of the present invention.

FIG. 5 is a circuit diagram as well.

[Explanation of symbols]

2 Fixed body (stator) 3a, 3b Electrostrictive element 20 Focusing lens optical system (movable lens) 21 Distance adjustment ring (rotating body) 21c Frictional contact portion 22 Ring plate spring (spring member) 23 Base tube (fixed member) 24 Outer cylinder (fixed cylinder) 25 First ring for bearing (bearing)

Claims (1)

[Claims] 1. A rotating body that has a cylindrical fixed cylinder, a bearing disposed at an inner diameter position of the fixed cylinder, and a stator, and is biased toward the optical axis by a spring member against the stator. comprises a vibration motor that rotates around the optical axis by vibration of the stator, and a movable lens, the rotating body and the bearing rotating body of the bearing are brought into contact in the optical axis direction, and the rotating body is rotated by a lens feeding mechanism. The movable lens is moved in the optical axis direction by the rotation of the vibration motor, and the fixed member receives the biasing force of the spring member in the vibration motor in the optical axis direction via the bearing rotating object. , a lens barrel using a vibration motor.