JP4614865B2 - Camera aperture device - Google Patents

Description

  The present invention relates to a motor used in a digital camera or the like.

  In recent years, digital cameras have become widespread and their functions have become multifunctional. A moving picture shooting function is added to a digital still camera dedicated to still images. In general, when taking a still image with a still camera, a sector (aperture blade) moves first to form an aperture opening of a predetermined size. Then, shooting is performed with the sector stopped at that position. However, when performing moving image shooting, the ambient brightness changes every moment, so it is necessary to adjust the size of the aperture opening accordingly. Therefore, in the moving image mode, shooting is performed while moving the sector.

  In the above video mode, audio can be recorded simultaneously. However, when a moving image is taken with a digital camera, a driving sound for controlling the diaphragm is generated. There is a problem that this driving sound is picked up by a microphone attached to the camera and reproduced as noise when the recording is reproduced. As a loud driving sound, there is vibration of the rotor in the motor that drives the diaphragm mechanism.

Therefore, for example, Patent Document 1 proposes a digital camera that reduces the influence of the driving sound of the aperture mechanism. This digital camera is provided with control means for controlling the motor so that the driving sound of the diaphragm mechanism is input during the sampling period of the analog audio signal to be recorded. In such a digital still camera, the motor drive is controlled so that the driving sound of the diaphragm mechanism is generated between a certain sampling time and the next sampling time. Therefore, it is possible to prevent the drive sound of the diaphragm mechanism from being recorded simultaneously.
JP 2004-23502 A

  However, the technique disclosed in Patent Document 1 performs complicated control of driving the motor so that the driving sound of the diaphragm mechanism is input during the sampling period of the audio signal. This control does not drive the motor during the sampling period, but controls the driving sound generated when the motor is driven during the sampling period, so that the control logic becomes complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor that can suppress the generation of drive sound of a diaphragm mechanism with a simple structure.

  An object of the present invention is to provide a motor including a holding member that rotatably holds a rotor formed of a permanent magnet having a plurality of poles magnetized in a radial direction, wherein the holding member is in a direction of a rotation axis of the rotor with respect to the rotor. This can be achieved by a motor formed of a magnetic resin that gives a magnetic attractive force to the motor.

  With this configuration, since a magnetic attractive force acts on the rotor in the direction of the rotation axis, the rotor is always urged toward the magnetic resin, and rattling between the rotor and the holding member in the direction of the rotation axis can be prevented. Therefore, the driving sound of the motor can be suppressed with a simple structure.

  The holding member includes a first holding member that holds the rotating shaft of the rotor, and a second holding that holds the rotating shaft of the rotor on a side facing the first holding member via the rotor. And a motor in which the first holding member or the second holding member is formed of the magnetic resin.

  With this configuration, the magnetic attraction force acts on the rotor in one of the first holding member and the second holding member, so that the rotor and the holding member can be prevented from rattling in the rotation axis direction. Driving noise can be suppressed.

  Further, according to the camera diaphragm device provided with the motor described above, it is possible to provide a camera diaphragm device in which the operation sound is suppressed.

  A motor that can suppress the generation of driving noise with a simple structure can be provided.

  Hereinafter, a camera diaphragm device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of main parts of the diaphragm device 1 in a state where the diaphragm opening is fully opened. FIG. 2 is a diagram showing the diaphragm device 1 when the diaphragm aperture is the smallest diaphragm MN. The aperture device 1 includes a substrate 2, a train wheel 15, a step motor 20, a control unit 30, and the like.

  In FIG. 1, the diaphragm device 1 includes a substrate 2 on which a circular diaphragm opening 2HL is formed. A diaphragm ring 5 that can rotate in the direction of the arrow RM is disposed so as to be parallel to the surface of the substrate 2. However, in the state shown in FIG. 1, the position of the aperture ring 5 is located at the end rotated clockwise, so that when the aperture opening has a small diameter, it is rotated counterclockwise from the state of FIG. . The aperture ring 5 has a ring opening 5HL at the center. The ring opening 5HL and the aperture opening 2HL of the substrate 2 have substantially the same shape, and the aperture ring 5 is disposed on the substrate 2 so that the apertures overlap each other.

  The diaphragm device 1 includes five sectors 10-1 to 10-5, and swings with the rotation of the diaphragm ring 5 to change the aperture diameter of the diaphragm opening 2HL. Each of the five sectors 10-1 to 10-5 has a point-symmetric posture with respect to the center point CP of the aperture opening 2HL, and is swung in the same manner by the aperture ring 5 to cooperate with each other. A diaphragm aperture is formed.

  On the substrate 2, five fixed shafts 3-1 to 3-5 are provided upright at equal intervals in the circumferential direction. Each of the five sectors 10 swings with the fixed shafts 3-1 to 3-5 as the support shafts. On the other hand, engagement pins 6-1 to 6-5 are erected on the diaphragm ring 5 at equal intervals in the circumferential direction. These engagement pins 6-1 to 6-5 are engaged with cam grooves 11-1 to 11-5 having predetermined shapes formed in the sectors 10-1 to 10-5. Therefore, each engagement pin 6 is moved by the rotation of the aperture ring 5 and slides in each cam groove 11, so that each sector 10 swings along a predetermined locus.

  FIG. 2 is a diagram showing a case where the aperture ring 5 is rotated counterclockwise from the aperture in the fully opened state shown in FIG. In FIG. 2, the position of the small aperture 2MN is shown by hatching so that the aperture that has been narrowed down can be easily confirmed.

  With reference to FIG. 1 again, the configuration of the drive system of the diaphragm device 1 will be described. As described above, when changing the aperture diameter, the aperture ring 5 is rotated. The aperture ring 5 includes a protruding portion 5PR that protrudes in the radial direction. A tooth row 5GA is formed at the tip of the protruding portion 5PR. This tooth row 5GA meshes with a wheel train 15 driven by a rotor kana 21 of the step motor 20. The drive of the step motor 20 is controlled by a control unit 30 serving as control means. Therefore, when the aperture device 1 is incorporated in a camera and used, the control unit 30 receives a predetermined aperture signal from the camera side, and controls the step motor 20 based on this signal to rotate the aperture ring 5. Each sector 10 is moved to a predetermined position to form a target aperture. As shown in FIG. 1, the control unit 30 drives the step motor 20 by switching the current supplied to the two drive coils CA and CB wound around the stator 23 arranged in the step motor 20. Take control.

  Next, the configuration of the step motor 20 will be described with reference to FIGS. 3, 4 and 5. FIG. 3 is a perspective view showing the appearance of the step motor 20. FIG. 4 is a front view showing the appearance of the step motor 20. 5 is a cross-sectional view taken along the line AA in FIG. Step motor 20 includes rotor kana 21, rotor 22, stator 23, rotor shaft 24, spacer 25, first case (first holding member) 27, second case (second holding member) 28, drive coils CA, CB, and the like. Composed.

  The rotor 22 is made of a permanent magnet formed in a cylindrical shape, and is magnetized with four poles in the radial direction so as to be integrated with the rotor shaft 24 by press-fitting or insert molding, and is rotatable. The first case 27 and the second case 28 hold the rotor 22 rotatably. Specifically, in the first case 27, the upper portion of the rotor shaft 24 is inserted into a hole provided in the first case 27 to hold the rotor shaft 24. The second case 28 is held in a state where the lower portion of the rotor shaft 24 passes through a hole provided in the second case 28 and protrudes below the second case 28. A rotor kana 21 is fixed to a portion of the rotor shaft 24 protruding from the second case 28. In addition, a spacer 25 penetrating the rotor shaft 24 is provided between the rotor 22 and the first case 27. The stator 23 is made of a magnetic member formed in a U shape, and the drive coils CA and CB are wound around it.

  Here, the first case 27 is formed of a magnetic resin that applies a magnetic attractive force to the rotor 22 in the direction of the rotor shaft 24. The magnetic resin refers to a material obtained by mixing a metal magnetic powder such as iron and a resin. As a result, a magnetic attraction force acts on the rotor 22 in the axial direction, so that the rotor 22 is urged in the direction indicated by the arrow B (to the first case 27 side) as shown in FIG. Rotation drive in the state. Thereby, rattling between the rotor 22 and the first case 27 and the second case 28 in the axial direction can be prevented, and the drive sound of the step motor 20 can be suppressed. As described above, the stepping motor 20 can suppress the generation of driving sound with a simple structure. The second case 28 is made of a normal resin.

  Further, the first case 27 can hold the rotor 22 in a rotatable manner and can give a magnetic attraction force to the rotor 22. In other words, the rotor 22 can be held and the magnetic attractive force can be applied with a single member. Therefore, the step motor can be reduced in thickness and size in the axial direction as compared with a case where a member for giving a magnetic attractive force to the rotor 22 is provided individually. Thereby, the step motor according to the present embodiment can be applied to a digital camera or the like that is required to be downsized. In addition, the manufacturing process can be facilitated as compared with the case where a member for giving a magnetic attraction force to the rotor 22 is provided individually.

  Further, the diaphragm device 1 using the step motor 20 according to the present embodiment is suitable for a digital still camera to which a moving image shooting function is added because the operation sound is suppressed.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible. For example, in the step motor according to the present embodiment, the first case 27 is made of magnetic resin and the second case 28 is made of ordinary resin. However, the first case 27 is made of ordinary resin and the second case 28 is made of second resin. The case 28 may be formed of a magnetic resin. In this embodiment, the step motor is used. However, the step motor may be used for other motors such as a swing motor and a DC motor.

It is the figure which showed the principal part structure of the aperture_diaphragm | restriction apparatus in the state which made the aperture opening fully open. It is the figure which showed the aperture_diaphragm | restriction apparatus when an aperture opening is made into the minimum aperture_diaphragm | restriction MN. 2 is a perspective view showing an external appearance of a step motor 20. FIG. FIG. 2 is a front view showing an external appearance of a step motor 20. It is AA sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diaphragm 2 Substrate 2HL Diaphragm opening 5 Diaphragm ring 10 Sector 20 Step motor 21 Rotor kana 22 Rotor 23 Stator 24 Rotor shaft 25 Spacer 27 First case 28 Second case 30 Controller CA, CB Drive coil

Claims (1)

A diaphragm device for a camera including a motor having a holding member that rotatably holds a rotor formed of a permanent magnet having a plurality of poles magnetized in a radial direction ,
The holding member is formed of a magnetic resin that applies a magnetic attraction force to the rotor in the direction of the rotation axis of the rotor, and the first holding member that rotatably holds the rotation shaft of the rotor; And a second holding member that is on the side facing the rotor through the rotor and rotatably holds the rotation shaft of the rotor,
Between the rotor and the first holding member is provided a spacer through which the rotation shaft of the rotor passes,
The rotor is rotatable in a state of contacting the spacer without contacting the first holding member;
An aperture device for a camera according to claim 1, wherein a surface of the spacer facing the rotor is smaller than a surface of the rotor facing the spacer.

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