JP2005352394A - Lens apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens apparatus which can be miniaturized by providing a position detecting means by utilizing a member to be driven that is provided spreadingly in a driving direction. <P>SOLUTION: The lens apparatus is provided with actuators 30, 30 for driving lens frames 18, 20. The actuator 30 is composed of piezo-electric elements 32A, 32B and driving members 34A, 34B and friction engagement of the driving members 34A, 34B to a plate 26 to be driven that is provided spreadingly in the driving direction is carried out to move the plate 26 to be driven in an optical axis direction. A photo-interrupter 42 and a photo-reflector 40 which are the position detecting means are attached to the plate 26 to be driven. The plate 26 to be driven is also used as a light shielding body of the photo-interrupter 42 or a reflection plate of the photo-reflector 40. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens device, and more particularly to a lens device mounted on a small precision device such as a digital camera or a mobile phone.

  There is an actuator using a piezoelectric element as a driving device for a lens unit of a digital camera or the like. For example, in the actuator of Patent Document 1, a driving rod is fixed to the end face of a piezoelectric element, and a lens barrel is slidably supported by the driving rod. A leaf spring is attached to the lens barrel, and a frictional force acts between the plate spring and the drive rod by the elastic force of the leaf spring. A drive pulse having a substantially sawtooth waveform is applied to the piezoelectric element, and the piezoelectric element is displaced at different speeds in the extending direction and the contracting direction. For example, when the piezoelectric element is gently displaced, the lens barrel moves together with the drive rod. Conversely, when the piezoelectric element is displaced rapidly, the lens barrel stops at the same position due to the inertia of its mass. Therefore, the lens barrel can be moved intermittently at a fine pitch by repeatedly applying a drive pulse having a substantially sawtooth waveform to the piezoelectric element.

  However, since the actuator described in Patent Document 1 transmits the driving force through the long drive rod, the vibration of the piezoelectric element is absorbed and attenuated by the drive rod, and the lens barrel is moved accurately. There was a problem that I could not. In particular, high-frequency vibration has a large attenuation factor due to the drive rod, and therefore the response of the lens barrel is deteriorated. Therefore, the actuator of Patent Document 1 can be controlled only with a low-frequency drive pulse, and there is a problem that the number of movements of the lens barrel per unit time is reduced. For this reason, in order to increase the moving speed of the lens barrel in the actuator of Patent Document 1, it is necessary to increase the applied voltage to increase the amount of displacement of the piezoelectric element and to increase the amount of movement of the lens barrel once. .

  In Patent Document 2, by increasing the power supply voltage of 5 V to 30 V, the amount of movement at one time is increased, and the moving speed of the lens barrel is increased. For this reason, in patent document 2, there existed a problem that a pressure | voltage rise apparatus was needed, the apparatus enlarged, and complicated control was needed.

  In the actuator described in Patent Document 3, an engagement member is attached to the end face of the displacement direction of the piezoelectric element, the engagement member is frictionally engaged with the moving plate, and the lens barrel is attached to the moving plate. . Then, by applying a driving pulse to the piezoelectric element, vibration is transmitted through the engaging member, and the moving plate and the lens barrel are moved.

Since the actuators described in Patent Documents 1 to 3 described above use a piezoelectric element as a drive source, they can be reduced in size compared to an actuator using a motor as a drive source.
Japanese Patent No. 2633066 Japanese Patent Laid-Open No. 2000-50660 Japanese Patent Laid-Open No. 10-232337

  By the way, when the actuators described in Patent Documents 1 to 3 are applied to a lens device, a position detection unit for detecting the position of the lens barrel is required. As the position detecting means, for example, a transmissive photo interrupter or a reflective photo reflector is used, and the actuator is driven and controlled based on the detection values of these position detecting means.

  Photointerrupters and photoreflectors themselves are very small, but there is a problem that the lens device is enlarged because of the large shades and reflectors.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a lens apparatus that can be miniaturized in a lens apparatus that includes an actuator using a piezoelectric element and a position detection means.

  In order to achieve the above object, the invention according to claim 1 is a piezoelectric element, a driving member integrally attached to the piezoelectric element, frictionally engaged with the driving member, and extended along the driving direction. In a lens apparatus comprising: a driven member provided; and a lens frame that is integrally attached to the driven member and is moved in the optical axis direction by the power of the piezoelectric element, the position of the lens frame is detected The position detecting means is formed using the driven member.

  According to the first aspect of the present invention, since the position detecting means is provided by using the driven member extending in the driving direction, the installation space for the position detecting means is reduced, and the lens apparatus is reduced in size. Can do. According to the first aspect of the present invention, since the position detecting means is provided on the driven member, the displacement amount of the lens frame can be accurately measured.

  According to a second aspect of the present invention, in the first aspect of the present invention, the position detecting means is a transmissive photo interrupter in which the driven member is a light shielding member. Although the photo interrupter can detect with high output and high accuracy, there is a problem that the installation space becomes large. However, according to the invention of claim 2, since the driven member also serves as the light interrupter of the photo interrupter. The lens device can be reduced in size.

  According to a third aspect of the present invention, in the first aspect of the present invention, the position detecting means is a reflective photo reflector in which a reflective surface is formed on the driven member. According to the invention described in claim 3, since the reflecting surface of the photo reflector is formed on the driven member, the installation space for the position detecting means can be reduced, and the lens device can be miniaturized.

  According to the lens device of the present invention, since the position detecting means is provided by using the driven member extending in the driving direction, the displacement amount of the lens device can be accurately measured and the lens device can be miniaturized. be able to.

  Hereinafter, preferred embodiments of a lens device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a main configuration of a lens apparatus according to the present invention. The lens device shown in FIG. 1 has a box-shaped case composed of a case body 12 and a lid 14, and a fixed lens 16 is attached to the side surface of the case body 12.

  Two lens frames 18 and 20 are provided inside the case body 12, and movable lenses such as a zoom lens and a focus lens are held in the two lens frames 18 and 20. The two lens frames 18 and 20 are supported by two guide rods 22 and 24 arranged in parallel with the optical axis of the fixed lens 16 so as to be slidable in the optical axis direction. That is, a guide portion 23 is formed to project from the outer peripheral surface of the lens frame 18, and the guide rod 24 is inserted and guided through the through hole of the guide portion 23, and is projected to the opposite side of the guide portion 23. When the guide rod 22 is engaged with the U-shaped groove of the engaging portion (not shown), the lens frame 18 is supported slidably in the optical axis direction. Similarly, a guide portion 25 is formed on the outer peripheral surface of the lens frame 20 so as to be guided by being inserted through the through hole of the guide portion 25, and protrudes on the opposite side of the guide portion 25. When the guide rod 24 is engaged with the U-shaped groove of the formed engaging portion 27, the lens frame 20 is supported slidably in the optical axis direction.

  Driven plates 26 and 26 are integrally formed on the lens frames 18 and 20, respectively. The driven plate 26 is formed in an elongated rectangular shape, and is arranged so that its longitudinal direction is parallel to the optical axis. The material of the driven plate 26 is not particularly limited, but a light and strong material such as ceramic is selected.

  Actuators 30 and 30 are disposed on the driven plates 26 and 26, respectively. Each actuator 30, 30 is fixed by being fitted into the opening of the lid 14.

  FIG. 2 is a perspective view for explaining the basic structure of the actuator 30. Hereinafter, an example of the actuator 30 that drives the lens frame 18 will be described, but the actuator 30 that drives the lens frame 20 is configured similarly.

  As shown in FIG. 2, the actuator 30 is mainly composed of piezoelectric elements 32 </ b> A and 32 </ b> B, drive members 34 </ b> A and 34 </ b> B, and a presser spring 36. The piezoelectric elements 32A and 32B are arranged on both sides of the driven plate 26. The piezoelectric elements 32A and 32B are arranged such that the displacement direction thereof is the longitudinal direction of the driven plate 26 (that is, the driving direction). On one end face of each piezoelectric element 32A, 32B in the displacement direction, presser plates 38A, 38B fixed to the case lid 14 (see FIG. 1) are disposed, and on the other end face, driving members 34A, 34B. Are integrally attached. The drive members 34A and 34B are formed in a substantially rectangular block shape, and are made of a light and rigid material such as ceramic, like the driven plate 26 described above. The driving members 34A and 34B are formed with recesses 35A and 35B on the side surface opposite to the side facing the driven plate 26, and the presser spring 36 is engaged with the recesses 35A and 35B. The presser spring 36 is a plate spring that sandwiches the two drive members 34 </ b> A and 34 </ b> B, and the drive members 34 </ b> A and 34 </ b> B are pressed against the driven plate 26 by the biasing force of the presser spring 36. As a result, the drive members 34 </ b> A and 34 </ b> B are frictionally engaged with the driven plate 26. As will be described later, the frictional force between the driving members 34A and 34B and the driven plate 26 is such that the frictional force becomes larger than the driving force when a driving pulse with a gradual voltage change is applied to the piezoelectric elements 32A and 32B. In addition, when a drive pulse having a sudden voltage change is applied to the piezoelectric elements 32A and 32B, the friction force is set to be smaller than the drive force.

  2 shows an example in which the presser spring 36 is used as a biasing means for biasing the driving members 34A and 34B to the driven plate 26, but other biasing means such as a compression spring or rubber is used. The driving members 34A and 34B may be individually urged by an elastic body.

  3A and 3B show examples of driving pulses applied to the piezoelectric elements 32A and 32B. 3A is a driving pulse for moving the lens frame 18 of FIG. 2 in the left direction, and FIG. 3B is a driving pulse for moving the lens frame 18 of FIG. 2 in the right direction. .

  As shown in FIGS. 3A and 3B, the same sawtooth drive pulse is simultaneously applied to the piezoelectric elements 32A and 32B. For example, in FIG. 3A, a drive pulse that rises gently from time β1 to time β2 and suddenly falls at time β3 is applied to the piezoelectric elements 32A and 32B. Therefore, from the time β1 to the time β2, the piezoelectric elements 32A and 32B are gently extended, and the driving members 34A and 34B move gently accordingly, so that the driven plate 26 is moved together with the driving members 34A and 34B. Thereby, the driven plate 26 of FIG. 2 can be moved to the left. At time β3, the piezoelectric elements 32A and 32B contract rapidly, so that the drive members 34A and 34B in FIG. 2 move to the right. At this time, since the driving members 34A and 34B move rapidly, only the driving members 34A and 34B move while the driven plate 26 stops at that position due to inertia. Therefore, by repeatedly applying the sawtooth drive pulse shown in FIG. 3 (A), the driven plate 26 of FIG. 2 repeats moving and stopping in the left direction, so that the lens frame 18 is moved in the left direction. be able to.

  In the case shown in FIG. 3B, a drive pulse that gently falls from time β4 to time β5 and rises sharply at time β6 is applied to the piezoelectric elements 32A and 32B. Therefore, from time β4 to time β5, the piezoelectric elements 32A and 32B are gradually contracted, and the driving members 34A and 34B move gently accordingly, so that the driven plate 26 moves together with the driving members 34A and 34B. Thereby, the driven plate 26 of FIG. 2 can be moved rightward. At time β6, the piezoelectric elements 32A and 32B are rapidly expanded, so that the driving members 34A and 34B move to the right in FIG. At this time, since the driving members 34A and 34B move rapidly, only the driving members 34A and 34B move while the driven plate 26 stops at that position due to inertia. Therefore, by repeatedly applying the sawtooth drive pulse shown in FIG. 3B, the driven plate 26 in FIG. 2 repeats the movement and the stop in the right direction, so that the lens frame 18 is moved in the right direction. be able to.

  By the way, the lens device of the present embodiment is provided with position detecting means for detecting the positions of the lens frames 18 and 20, as shown in FIG. As the position detection means for detecting the position of the lens frame 18, a reflection type photo reflector 40 is used, and as the position detection means for detecting the position of the lens frame 20, a transmission type photo interrupter 42 is used. FIG. 5 is a front view of the lens device of FIG.

  The photo interrupter 42 is arranged alongside the actuator 30 along the driven plate 26 integral with the lens frame 18. Further, the photo interrupter 42 is formed in a gate shape, the lower part is divided into two parts, a light emitting part is provided on one side, and a light receiving part is provided on the other side. The driven plate 26 is inserted / removed between the light emitting part and the light receiving part. That is, when the actuator 30 is driven, the driven plate 26 is driven in the direction of the optical axis, and the tip thereof is inserted / removed between the light emitting portion and the light receiving portion. Therefore, the position of the driven plate 26 can be detected by projecting light from the light emitting portion of the photo interrupter 42 toward the light receiving portion, receiving the light at the light receiving portion, and detecting the amount of light.

  In the position detecting means configured as described above, since the driven plate 26 also serves as a light shield for the photo interrupter 42, it is not necessary to newly provide a light shield. Further, since the position of the driven plate 26 driven by the actuator 30 is directly detected by the photo interrupter 42, the position can be accurately detected.

  On the other hand, the photo reflector 40 is arranged alongside the actuator 30 along the driven plate 26 integral with the lens frame 20. The photo reflector 40 includes a light projecting unit and a light receiving unit, and is configured to receive the reflected light of the light emitted from the light projecting unit with the light receiving unit and detect the amount of light. The photo reflector 40 is supported by a support member 44 attached to the case lid 14 (see FIG. 1), and is disposed to face the driven plate 26.

  A reflective plate 46 is attached to the surface of the driven plate 26 on the photo reflector 40 side. A plurality of reflectors 48 are arranged on the reflecting plate 46 at regular intervals in the longitudinal direction of the driven plate 26. Therefore, the amount of movement of the driven plate 26 can be detected by detecting the reflector 48 of the reflecting plate 46 with the photo reflector 40.

  In the position detecting means configured as described above, since the reflection plate 46 is provided on the driven plate 26, it is not necessary to newly provide a reflection member for the photo reflector 40. Further, since the position of the driven plate 26 driven by the actuator 30 is directly detected by the photo reflector 40, the position can be accurately detected.

  Next, the operation of the lens apparatus configured as described above will be described.

  FIG. 6 shows a front view of a lens apparatus in which a position detection means is attached by a general method as a lens apparatus of a comparative example. In the lens apparatus shown in the figure, a photo reflector 40 and a photo interrupter 42 as position detecting means are arranged in a free space below. The photo reflector 40 is fixed to the case main body 12 (see FIG. 1) via an L-shaped support member 52, and the photo interrupter 42 is directly fixed to the case main body 12 (see FIG. 1). The light blocking body 50 inserted into and removed from the photo interrupter 42 is formed integrally with the lens frame 20 and extends in the optical axis direction. On the other hand, the reflection plate 46 for the photo reflector 40 is supported by a support member 54 integrally formed with the lens frame 18, and the support member 54 and the reflection plate 46 are extended in the optical axis direction.

  Therefore, in the lens device of FIG. 6, the light shielding body 50 and the support member 54 of the reflection plate 46 are extended in the optical axis direction, and a large space is required. Furthermore, since the light shielding body 50 and the support member 54 are formed integrally with the lens frames 18 and 20 and move together with the lens frames 18 and 20 in the optical axis direction, it is necessary to secure a space for them. Therefore, the lens device of FIG. 6 requires a large space below the lens frames 18 and 20, and there is a problem that the lens device becomes large.

  On the other hand, the lens device of the present embodiment shown in FIGS. 4 and 5 constitutes a position detecting means using a driven plate 26 extending in the optical axis direction. That is, in the position detection means on the lens frame 18 side, the driven plate 26 also serves as a light shield for the photo interrupter 42, and the position detection means on the lens frame 20 side reflects the reflection for the photo reflector 40 on the driven plate 26. A plate 46 is provided. Accordingly, the light shielding body 50 and the support member 54 for the reflection plate 46 shown in FIG.

  As described above, according to the lens device of the present embodiment, since the position detection unit is configured using the driven plate 26, the installation space for the position detection unit can be reduced, and the lens device can be downsized. Can do. Furthermore, in the present embodiment, the photo interrupter 42 and the photo reflector 40 are arranged in a vacant space adjacent to the actuator 30, so that the lens device can be further downsized.

  In the present embodiment, the position of the driven plate 26 moved by the actuator 30 is directly detected by the photo interrupter 42 and the photo reflector 40, so that the amount of movement of the driven plate 26 is accurately measured. Can do. Therefore, by controlling the actuator 30 based on the detection values of the photo reflector 40 and the photo interrupter 42, the drive control of the lens frames 18 and 20 can be performed with high accuracy.

  In the above-described embodiment, the photo reflector 40 is used as the position detection unit of the lens frame 18 and the photo interrupter 42 is used as the position detection unit of the lens frame 20. However, the present invention is not limited to this. A reflector 40 or a photo interrupter 42 may be used.

  In the above-described embodiment, a substantially sawtooth drive pulse is applied to the piezoelectric elements 32A and 32B. However, the shape of the drive pulse to be applied is not limited to this. For example, the drive pulses shown in FIGS. 7A and 7B may be applied. In the case of FIG. 7A, a substantially sawtooth drive pulse voltage that rises gently from time α1 to time α2 and falls sharply at time α3 is applied to the piezoelectric element 34A. A voltage of a substantially sawtooth drive pulse that gradually rises from time α1 to time α2 and sharply falls at time α4 is applied. Therefore, the timing at which the piezoelectric element 34A contracts rapidly and the timing at which the piezoelectric element 34B contracts rapidly are shifted by an interval between the time α3 and the time α4. Similarly, in the case of FIG. 7B, a substantially sawtooth drive pulse voltage that gently falls from time α5 to time α6 and rapidly rises at time α7 is applied to the piezoelectric element 34A. A voltage of a substantially sawtooth drive pulse that gently falls from time α5 to time α6 and rapidly rises at time α8 is applied to 34B. Therefore, the timing at which the piezoelectric element 34A rapidly expands and the timing at which the piezoelectric element 34B rapidly expands are shifted by an interval between the time α7 and the time α8.

  When the timing at which the piezoelectric elements 34A and 34B are suddenly deformed is shifted as described above, the drive member 36B is stopped when the drive member 36A is suddenly moved, and the drive member 36B is suddenly moved. The drive member 36A is stopped. For this reason, the driven plate 26 is hardly moved by being driven by the driving members 36A and 36B, and the driven plate 26 can be surely stopped. Therefore, by applying a voltage like the above drive pulse, the movement and stop of the driven plate 26 can be controlled reliably, and the drive control of the driven plate 30 can be performed accurately.

  The lens device described above can be applied to small precision devices such as digital cameras and mobile phones. In particular, the cellular phone needs to be driven at a low voltage of 3 V or less. However, by using the lens device of the present invention, it can be driven even at a high frequency of about 20 kHz. It can be moved at a high speed of s or more. Therefore, even a zoom lens that needs to move about 10 mm can be moved quickly.

1 is an exploded perspective view showing a configuration of a lens device according to the present invention. The perspective view which shows the structure of the actuator of this Embodiment Waveform diagram of drive pulse applied to piezoelectric element of FIG. The perspective view which shows the structure of the lens apparatus which attached the position detection means. Front view of the lens device of FIG. Front view showing a lens device of a comparative example Waveform diagram of drive pulse with different shape from FIG.

Explanation of symbols

  18, 20 ... Lens frame, 32A, 32B ... Piezoelectric element, 34A, 34B ... Drive member, 36 ... Presser spring, 40 ... Photo reflector, 42 ... Photo interrupter

Claims (3)

A piezoelectric element; a driving member integrally attached to the piezoelectric element; a driven member frictionally engaged with the driving member and extending along a driving direction; and the driving member integrally In a lens device comprising a lens frame attached and moved in the optical axis direction by the power of the piezoelectric element,
A lens device, wherein position detecting means for detecting the position of the lens frame is formed using the driven member.   The lens apparatus according to claim 1, wherein the position detection unit is a transmissive photointerrupter that uses the driven member as a light blocking body.   The lens apparatus according to claim 1, wherein the position detection unit is a reflection type photo reflector in which a reflection surface is formed on the driven member.

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