JP5072787B2 - Optical equipment - Google Patents

Description

  The present invention relates to an optical device that moves a movable lens in an optical axis direction by an actuator such as a voice coil motor.

  Optical devices such as an imaging device and an interchangeable lens are provided with a movable lens that can move in the optical axis direction of the optical system and an actuator that moves the optical lens in order to perform zooming and focus adjustment.

  As the actuator, a stepping motor, a DC motor, and a vibration motor are used, and as disclosed in Patent Document 1, a voice coil motor (linear motor) including a coil, a magnet, and a yoke is also used. .

Further, in the optical device (lens barrel) disclosed in Patent Document 1, an elastic member is disposed between a yoke constituting the voice coil motor and a base member (fixing member) of the lens barrel. Thereby, the vibration generated in the magnet when the coil of the voice coil motor is energized is not directly propagated to the base member or the lens barrel member held by the base member, thereby reducing the noise caused by the vibration.
Japanese Patent Laid-Open No. 07-039129

  However, in the optical device disclosed in Patent Document 1, it is possible to suppress the vibration generated in the magnet of the voice coil motor from propagating to the lens barrel member or the like, but the vibration generated as follows. Propagation cannot be suppressed.

  In a general optical apparatus, a lens is held by a lens holding member, and the lens holding member is provided with a sleeve portion and a rotation stop portion (U-groove portion) that engage with a bar member extending in the optical axis direction. Thereby, the lens holding member is guided in the optical axis direction, or the rotation of the lens holding member around the optical axis is prevented. A certain amount of backlash is required between the bar member, the sleeve portion, and the rotation stop portion.

  However, even if the backlash at the time of assembling the optical device is small, the backlash increases due to wear due to long-term use of the optical device. Furthermore, the direction of thrust generated by the voice coil motor may not be parallel to the optical axis direction, or the center of thrust and the center of gravity of the lens holding member including the lens may not coincide.

  In these cases, a twist occurs between the sleeve portion or the rotation stop portion and the bar member. For this reason, when the voice coil motor is operated, vibration in a direction other than the optical axis direction is generated by the twisting, and the vibration is propagated to the barrel member via the bar member, and noise of a specific frequency is generated. . Moreover, the vibration also affects the lens position control, which may reduce the lens position accuracy.

  The present invention provides an optical apparatus capable of preventing the generation of noise caused by the vibration generated by the engagement play between the lens holding member and the bar member and the deterioration of the lens position accuracy.

An optical apparatus according to an aspect of the present invention holds a first movable lens and is movable in the optical axis direction, and drives the first lens holding member in the optical axis direction. An actuator, a bar member that engages with the first lens holding member, guides the first lens holding member in the optical axis direction, or prevents rotation of the first lens holding member; and the actuator A support member having a bar support portion that holds and supports the bar member; a second lens holding member that holds the second movable lens and is movable in the optical axis direction; and the second lens hold A cylindrical member that supports the member so as to be movable in the optical axis direction, and a damping member is disposed between the bar support portion and the cylindrical member.

  According to the present invention, by providing the damping member, it is possible to suppress the generation of noise and the deterioration of the lens position accuracy due to the vibration generated by the engagement play between the first lens holding member and the bar member. Can do.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a configuration of a lens barrel portion of an imaging apparatus (digital still camera or video camera) as an optical apparatus that is an embodiment of the present invention. FIG. 1 is a side cross-sectional view of the lens barrel portion at the retracted position, and FIG. 2 is a top cross-sectional view at the retracted position.

  The lens barrel portion includes, in order from the object side, a first lens unit L1, a second lens unit L2, a third lens unit (correction lens that is an anti-vibration lens) L3, and a fourth lens unit (focus lens) L4. The optical system is accommodated. AXL is the optical axis of the optical system. The focus lens L4 corresponds to the first movable lens, and the first lens unit L1 and the second lens unit L2 correspond to the second movable lens.

  Reference numeral 1 denotes a first lens barrel that holds the first lens unit L1. Cam pins 1a are attached to three locations on the inner peripheral surface of the first barrel 1 in the circumferential direction. The cam pins 1a engage with three cam grooves 8a formed on the outer peripheral surface of the cam barrel 8, respectively. ing. In addition, rectilinear grooves (not shown) extending in the optical axis direction are formed at three locations in the circumferential direction on the inner peripheral surface of the first lens barrel 1, and the rectilinear grooves are formed on the outer peripheral surface of the fixed cylinder 7. The formed linear key (7a in FIG. 5) is engaged.

  Reference numeral 2 denotes a second lens barrel that holds the second lens unit L2. Cam pins 2 a are attached to three places in the circumferential direction on the outer peripheral surface of the second lens barrel 2. The cam pin 2 a is engaged with three cam grooves 8 b formed on the inner peripheral surface of the cam cylinder 8. The cam pin 2a is engaged with a rectilinear groove (7b in FIG. 5) formed in the fixed cylinder 7 so as to extend in the optical axis direction.

Solid Teitsutsu (cylindrical member) 7, so as not to rotate the first barrel 1 and the second lens barrel 2, and is held so as to be movable in the optical axis direction. Cam pins (not shown) are attached to three places on the outer peripheral surface of the fixed cylinder 7 in the circumferential direction. The cam pins are respectively engaged with three cam grooves 8 e formed on the inner peripheral surface of the cam cylinder 8. Match.

  The first lens barrel 1 and the second lens barrel 2 correspond to a second lens holding member.

  Reference numeral 5 denotes an aperture unit. A cam pin 5 a provided on the outer peripheral surface of the aperture unit 5 is engaged with a cam groove 8 d formed on the inner peripheral surface of the cam cylinder 8. The aperture unit 5 is formed with a sleeve portion 5b and a rotation stop portion (not shown), which are guided by guide bars 21 and 22 supported by a second lens barrel 2 and an image sensor base plate 9 described later in the optical axis direction. Is movably engaged. The aperture unit 5 also functions as a shutter in still image shooting.

  Reference numeral 3 denotes a third holding frame that holds the correction lens L3. The correction lens L3 and the third holding frame 3 are part of the image stabilization unit. The third holding frame 3 is held by a sensor holding frame 32 of the image stabilization unit so as to be shiftable in a direction orthogonal to the optical axis AXL (hereinafter, optical axis orthogonal direction). Reference numeral 31 denotes a coil holding frame that constitutes the base portion of the vibration isolation unit together with the sensor holding frame 32.

  A cam pin 3 a is provided on the outer peripheral surface of the sensor holding frame 32, and the cam pin 3 a is engaged with a cam groove 8 c formed on the inner peripheral surface of the cam cylinder 8. The sensor holding frame 32 is formed with a sleeve portion 3b and a rotation stop portion (not shown). The sleeve portion 3 b and the rotation stop portion are engaged with guide bars 21 and 22 supported by the second lens barrel 2 and the imaging element base plate 9, respectively.

  As described above, the guide bars 21 and 22 supported by the second barrel 2 hold the diaphragm unit 5 and the image stabilizing unit so as to be movable in the optical axis direction so as not to rotate.

Reference numeral 4 denotes a fourth holding frame as a first lens holding member that holds the focus lens L4. As shown in FIG. 4, the fourth holding frame 4 has a sleeve portion 4a and a rotation stop portion 4b. The sleeve portion 4a and the rotation stop portion 4b can be moved in the optical axis direction by guide bars (bar members) 65 and 66 supported by a focus base member 6 as a support member and an image pickup element base plate 9 as a base member, respectively. Is engaged.

  A gear portion (not shown) is formed on the outer peripheral surface of the cam cylinder 8, and a rotational force is transmitted to the gear portion from a zoom motor (stepping motor or the like) (not shown) via a gear train. Thereby, the cam cylinder 8 is rotationally driven. When the cam cylinder 8 rotates, the cam cylinder 8 moves in the optical axis direction while rotating due to the engagement of the cam groove 8e formed in the cam cylinder 8 and the cam pin of the fixed cylinder 7.

  The first lens barrel 1 includes an engagement between a cam pin 1a provided on the first lens barrel 1 and a cam groove 8a formed on the cam barrel 8, and a rectilinear groove and a fixed cylinder formed on the first lens barrel 1. 7 is moved in the optical axis direction without rotating.

  The second lens barrel 2 is rotated by engagement between a cam pin 2 a provided in the second lens barrel 2, a cam groove 8 b formed in the cam tube 8, and a rectilinear groove 7 b formed in the fixed tube 7. Without moving in the direction of the optical axis. The first lens barrel 1 and the second lens barrel 2, that is, the first lens unit L1 and the second lens unit L2 are moved in the optical axis direction, so that zooming is performed.

  In the aperture unit 5, the cam pin 5 a provided in the aperture unit 5 and the cam groove 8 d formed in the cam cylinder 8 are engaged, and the sleeve portion 5 b and the rotation stop portion 5 c are guided by the guide bars 21 and 22. Thus, the optical axis moves without rotating.

  The third holding frame 3 is configured such that the cam pin 3a provided on the third holding frame 3 and the cam groove 8c formed in the cam cylinder 8 are engaged, and the sleeve portion 3b and the rotation stop portion 3c are guided by the guide bars 21 and 22. By being guided, it moves in the optical axis direction without rotating.

  The image pickup device ground plane 9 holds an image pickup device 11 constituted by a CCD sensor or a CMOS sensor, and an infrared cut / low pass filter 10. The fixed cylinder 7 and the focus base member 6 are fixed (coupled) to the image sensor base plate 9 by screws (not shown). That is, the imaging element base plate 9 holds the image side end portions in the optical axis direction of the focus base member 6 and the fixed cylinder 7 respectively.

  Next, a focus drive mechanism that drives the fourth holding frame 4 that holds the focus lens L4 will be described with reference to FIGS. FIG. 3 is a perspective view showing a state where the focus drive mechanism is being assembled. FIG. 4 is an exploded perspective view of the focus drive mechanism.

  An air-core coil 41 having a rectangular tube shape is fixed to the fourth holding frame 4. The air core portion of the coil 41 is open toward the optical axis direction. A flexible substrate 42 is connected to the coil 41.

  Further, yokes 61 and 62 and a magnet 63 are fixed to the focus base member 6. The yoke 61 is formed in a U shape and is arranged so that the upper and lower surfaces extend in the optical axis direction. A magnet 63 is held inside the yoke 61. The yoke 61 is inserted inside the air-core coil 41. The coil 41, the yoke 61, and the magnet 63 are arranged at a predetermined interval.

  The magnet 63 extends with the optical axis direction as the longitudinal direction, and is magnetized in the direction perpendicular to the optical axis. A yoke 62 formed in an H shape is assembled to the U-shaped open end of the yoke 61. The coil 41, the yokes 61 and 62, and the magnet 63 constitute a linear actuator (voice coil motor) as a focus actuator.

  When the coil 41 is energized, the fourth holding frame 4 (that is, the focus lens L4) moves in the optical axis direction, that is, along the optical axis, by the action of the magnetic circuit formed by the yokes 61 and 62 and the magnet 63. At this time, the fourth holding frame 4 is guided in the optical axis direction by the guide bar 65 in the sleeve portion 4a, and the rotation around the guide bar 65 is prevented by the guide bar 66 in the rotation stop portion 4b.

  An encoder magnet 43 that extends in the optical axis direction is attached to the fourth holding frame 4. An MR sensor 67 as a magnetic sensor fixed to the focus base member 6 is disposed at a position facing the encoder magnet 43. When the encoder magnet 43 moves with respect to the MR sensor 67 together with the fourth holding frame 4, the magnetism acting on the MR sensor 67 changes, and the output from the MR sensor 67 also changes. Based on this output change, a control circuit (not shown) can detect the position of the fourth holding frame 4. The control circuit controls the current supplied to the coil 41 while referring to the position information of the fourth holding frame 4 detected through the MR sensor 67, and moves the focus lens L4 to the target position (focus position).

  Further, the focus base member 6 is provided with a bar support portion 6a that supports an end portion of the guide bar 65 in the optical axis direction (an end portion on the side opposite to the imaging element base plate 9).

  On the other hand, as shown in FIG. 5, a protruding portion (receiving surface) 7d is formed on the inner periphery of the fixed cylinder 7 so as to protrude so as to face the bar support portion 6a in the optical axis direction. And between the bar support part 6a and the protrusion part 7d, the rubber member 68 as a damping member (elastic member) is arrange | positioned. That is, the rubber member 68 is sandwiched between the bar support portion 6a and the protruding portion 7d in the optical axis direction.

  By providing the rubber member 68, the optical axis direction generated by the engagement play between the sleeve portion 4a of the fourth holding frame 4 and the guide bar 65 or the engagement play between the rotation stop portion 4b and the guide bar 66 is provided. It is possible to suppress the occurrence of vibrations in directions other than (propagation to the fixed cylinder 7). The rubber member 68 can also suppress the propagation of vibration in the optical axis direction generated in the magnet 63 to the fixed cylinder 7 when the voice coil motor is operated. That is, the resonance point where the drive frequency of the voice coil motor and the natural frequency of the fourth holding frame 4 including the guide bars 65 and 66 and the focus lens L4 coincide is moved to the high frequency side by providing the rubber member 68, Thereby, generation | occurrence | production of a vibration can be suppressed.

  As a result, it is possible to prevent the occurrence of noise and the deterioration of the lens position accuracy due to the vibrations.

  It is also possible to increase the rigidity of the focus base member 6 itself, or to increase the rigidity of the focus base member 6 and the fixed cylinder 7 by fixing them with screws to form an integral part. However, the former method is difficult for a small lens barrel because of the layout. Further, in the latter method, the fixed cylinder 7 is deformed or tilted by fixing the screw, and the positional accuracy of the first and second lens barrels 1 and 2 with which the fixed cylinder 7 is linearly guided decreases or falls. May be caused.

  On the other hand, in the present embodiment in which the rubber member 68 is provided, it can be applied without difficulty to a small lens barrel portion, and the fixed barrel 7 is not deformed or collapsed.

  FIG. 6 shows a Bode diagram in the case of the present embodiment in which the rubber member 68 is provided. FIG. 7 shows a Bode diagram when the rubber member 68 is not provided. In these figures, the horizontal axis represents frequency (Hz), the vertical axis represents phase (degree) in the upper diagram, and gain (db) in the lower diagram.

  When the rubber member 68 is not provided (FIG. 7), another amplitude ratio peak occurs near 200 Hz in addition to the primary resonance point near 70 Hz, and the phase also changes slightly. Since there is only one resonance point of vibration in the optical axis direction, it is considered that vibration is generated in directions other than the optical axis direction. That is, it is considered that vibration is generated due to the backlash between the sleeve portion 4a of the fourth holding frame 4 and the guide bar 65 or between the rotation stopper portion 4b and the guide bar 66.

  On the other hand, in the case of the embodiment provided with the rubber member 68 (FIG. 6), since the vibration due to this engagement backlash is absorbed by the rubber member 68, the peak as shown in FIG. Characteristics obtained.

  The embodiments described above are merely representative examples, and various modifications and changes can be made to the embodiments when the present invention is implemented.

  For example, in the above-described embodiment, the case where the rubber member is used as the damping member has been described. However, another elastic member such as a spring member may be used as the damping member.

  Moreover, although the said Example demonstrated the case where the 4th holding frame 4 was driven with a voice coil motor, even when using actuators other than a voice coil motor, the same effect by a damping member can be acquired.

  In the above embodiment, the case where the magnetic sensor is used to detect the positions of the correction lens L3 and the focus lens L4 has been described. However, instead of this, an optical sensor may be used.

  Furthermore, although the imaging apparatus has been described in the above embodiment, the present invention can also be applied to an interchangeable lens (optical apparatus).

1 is a side cross-sectional view illustrating a configuration of a lens barrel portion (collapse position) of an imaging apparatus that is an embodiment of the present invention. FIG. 3 is a top cross-sectional view illustrating a configuration of a lens barrel portion (collapse position) of the embodiment. The perspective view of the focus drive mechanism in the lens-barrel part of an Example. FIG. 3 is an exploded perspective view of the focus driving device. The perspective view which shows the assembly | attachment state of the focus drive mechanism and fixed cylinder of the lens-barrel part of an Example. The board diagram in the Example which provided the damping member. The board diagram in case the damping member is not provided.

Explanation of symbols

L1 First lens unit L2 Second lens unit L3 Third lens unit (anti-vibration lens, correction lens)
L4 4th lens unit (movable lens, focus lens)
DESCRIPTION OF SYMBOLS 1 1st lens barrel 2 2nd lens barrel 3 3rd holding frame 31 Coil holding frame 32 Sensor holding frame 33a, 33b Magnet 34a, 34b Coil 37a, 37b Hall sensor 4 4th holding frame 41 Air core coil 5 Diaphragm unit 6 Focus Base member 61, 62 Yoke 63 Magnet 65, 66 Guide bar 68 Rubber member 7 Fixed cylinder 9 Imaging element base plate

Claims (5)

A first lens holding member that holds the first movable lens and is movable in the optical axis direction;
An actuator for driving the first lens holding member in the optical axis direction;
A bar member that engages with the first lens holding member, guides the first lens holding member in the optical axis direction, or prevents rotation of the first lens holding member;
A support member having a bar support portion that holds the actuator and supports the bar member;
A second lens holding member that holds the second movable lens and is movable in the optical axis direction;
A cylindrical member that supports the second lens holding member so as to be movable in the optical axis direction;
An optical device, wherein a damping member is disposed between the bar support portion and the cylindrical member. A base member for holding an image side end portion in the optical axis direction of each of the support member and the cylindrical member;
The said damping member is arrange | positioned between the said cylindrical member and the edge part on the opposite side to the said base member in the said optical axis direction among the said bar support parts. Optical equipment. The optical apparatus according to claim 1, wherein a receiving surface that sandwiches the vibration damping member in the optical axis direction is formed between the cylindrical member and the bar support portion.   The optical apparatus according to any one of claims 1 to 3, wherein the actuator is a voice coil motor. An imaging device comprising the optical apparatus according to claim 1.