JP2014016582A - Light amount adjustment device and optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light amount adjustment device that can accurately adjust a switch position in accordance with a step of a driving motor.SOLUTION: The light amount adjustment device comprises: a cum plate 103 in which a cum groove is formed; a bottom plate 105 that covers the cum plate; a diaphragm blade 101 that is arranged between the cum plate and the bottom plate; a rotary ring 102 that is arranged between the cum plate and the bottom plate and drives the diaphragm blade; a motor that drives the rotary ring; and sensors 107 and 108 that are attached to the bottom plate and detect an open position of the diaphragm blade. A mutually engaging gear tooth part 105a is formed on respective mounting faces of the sensor and the bottom plate.

Description

  The present invention relates to a light amount adjusting device and an optical device that are mounted on an optical device such as a camera or an interchangeable lens and are also referred to as a diaphragm device.

  In a conventional light amount adjusting device, for example, as described in Patent Document 1, a rotating ring that drives a diaphragm blade is rotatably disposed between a cam plate and an annular ground plate. And if a rotation ring rotates with respect to a cyclic | annular baseplate according to the change of a focal distance, an aperture blade will be driven and an open aperture will change. In addition, the following diaphragm device has been proposed for an electric diaphragm device configured to change a diaphragm by rotating a rotating ring by a motor. That is, a photo interrupter that constitutes an aperture opening detection switch is attached to the storage case, and the storage case is attached to the annular base plate via screws. The light shielding plate extending from the rotating ring shields the optical path of the photo interrupter so that the position of the storage case can be adjusted in the circumferential direction. To change the position of the switch, remove the screw and adjust.

JP 7-199273 A

  However, the above conventional example has the following drawbacks. Remove the screw to adjust the switch position. However, since the change movement distance is not regulated, fine adjustment cannot be performed. Alternatively, a special jig is necessary for fine adjustment.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a light amount adjusting device and an optical apparatus that can adjust the switch position with high accuracy according to the step of the drive motor.

  A light quantity adjusting device according to the present invention includes a cam plate having a cam groove formed thereon, a ground plate covering the cam plate, a diaphragm blade disposed between the cam plate and the ground plate, and the cam plate and the ground plate. A rotating ring for driving the diaphragm blades, a motor for driving the rotating ring, and a sensor that is attached to the main plate and detects the opening position of the diaphragm blades, Each mounting surface of the base plate is formed with gear tooth portions that mesh with each other.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the light quantity adjustment apparatus and optical apparatus which can adjust a switch position accurately according to the step of a drive motor.

1 is an exploded perspective view of an aperture device for a camera lens according to an embodiment of the present invention. 1 is a partial cross-sectional view of a camera lens aperture device according to an embodiment of the present invention. The figure which shows the precision of F value and a light quantity. The figure which shows the precision of F value and light quantity when the open position of a diaphragm varies. The figure which shows the camera as an optical apparatus by which the aperture_diaphragm | restriction apparatus of one Embodiment is mounted.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A camera lens aperture device, which is an example of an optical apparatus that is an embodiment of a light amount adjusting device of the present invention, will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an exploded perspective view of a camera lens aperture device of the present embodiment. In FIG. 1, a diaphragm blade 101 that is a thin plate includes a cam plate 103 having a cam groove 103b for moving the diaphragm blade 101 to a predetermined opening amount, and a rotating ring 102 that holds a pin 101a at the center of rotation of the diaphragm blade 101. It is placed between. The cam plate 103 and the rotating ring 102 form a diaphragm blade ring. An annular ground plate 105 is fixed to the cam plate 103 with screws or the like so as to sandwich the aperture blade 101 and the rotating ring 102.

  When the driving force transmission unit 104 rotatably supported on the annular base plate 105 is rotated by a stepping motor (not shown), the rotation is transmitted to the rack 102a of the rotating ring 102 via the gear 6 press-fitted into the driving force transmission unit 104. The rotating ring 102 rotates around the optical axis that is the center of the opening 103 a of the cam plate 103. Since the hole 102 a of the rotating ring 102 is engaged with the pin 101 a at the rotation center of the diaphragm blade 101, the cam pin 101 b of the diaphragm blade 101 slides along the cam groove 103 b of the cam plate 103 by the rotation of the rotating ring 102. Then, it is narrowed down to a predetermined throttle diameter.

  Next, a switch configuration unit for detecting the opening position of the diaphragm used in the diaphragm device of this embodiment will be described with reference to FIG.

  A sensor 107 that is a photo interrupter is incorporated in a storage case 108 and fixed to the annular base plate 105 with screws 120. In this state, the legs 107a of the sensor 107 are soldered to a flexible printed board (not shown). The sensor 107 has an opening position (rotation position) of the aperture blade 101 by the light shielding plate 102b provided on the rotating ring 102 entering the slit of the sensor 107 and blocking light between the light emitting part and the light receiving part of the sensor 107. ) Is detected (see FIG. 1). A gear tooth profile portion 108 a is formed in the storage case 108 of the sensor 107, and is configured to engage with the gear tooth profile portion 105 a of the same shape formed on the annular base plate 105. The tooth pitches of these gear tooth portions 108a and 105a (one tooth interval) are set so that the rotation ring 102 is driven when a driving stepping motor (not shown) for driving the driving force transmission unit 104 is operated in one step of 1-2 phase driving. It is the same pitch that moves.

  Next, aperture evaluation will be described with reference to FIGS.

  The characteristics of the camera lens aperture device are evaluated by converting the difference between the design F value of each step of the 1-2 phase drive and the actual light quantity of each step into an eV value. When the aperture device for the camera lens is completed as designed, the light amount difference becomes zero as shown in FIG.

  However, the characteristics of the actual camera lens aperture device vary between B1 and B2 in FIG. This is due to backlash due to part tolerance, assembly error, and clearance for sliding. In addition, since the influence of variation becomes larger on the small aperture side, the range on the small aperture side becomes wider. Also, if the switching position of the sensor 107 varies, the amount of light when the aperture blade 101 is opened changes, so that C and D in FIG.

  In the case of C in FIG. 4, since the switching position of the sensor 107 is switched earlier than the original position, the actual aperture is brighter than the designed F value. Conversely, in the case of D, it indicates that the actual aperture is darker than the design F value because the switching position of the sensor 107 is switched later than the original position.

  Next, the effect of this embodiment will be described.

  When the first stage of the aperture = 1 eV is operated in 8 steps, the light amount change per step is (1/8) eV. In this embodiment, since the tooth pitch of the gear tooth profile 108a of the storage case 108 of the sensor 107 is the same as this one step, the amount of movement of one tooth is (1/8) eV light amount change. That is, by moving the position of the sensor 107 by one tooth, the amount of light when the aperture is opened can be adjusted in units of (1/8) eV.

  That is, if the storage case 108 is moved by one tooth in the direction in which the rotary ring 102 performs the narrowing operation, the switching position of the sensor 107 is delayed, and if the state before the storage case 108 is moved is C in FIG. Similarly, when the storage case 108 is moved by one tooth in the direction in which the rotating ring 102 performs the opening operation, the switching position of the sensor 107 is accelerated, and before the storage case 108 is moved, D changes to A 'in FIG.

  As a result, by accurately adjusting the position of the sensor that detects the open position of the rotating ring 102, it becomes possible to easily reduce the variation in the characteristics of the diaphragm.

  FIG. 5 shows a camera (video camera or still camera) as an optical apparatus on which the diaphragm device 10 of the present embodiment described above is mounted. Reference numeral 50 denotes a camera body, and reference numerals 51 and 53 denote a plurality of lenses. The lenses 51 and 53 and the diaphragm device 10 constitute a photographing optical system. An image sensor 52 includes a CCD sensor, a CMOS sensor, or the like, and photoelectrically converts a subject image formed by the photographing optical system. Reference numeral 54 denotes a controller composed of a CPU or the like, which controls the operation of the diaphragm device 10 (drive unit 1) and the image sensor 52. The aperture device 10 may have a shutter function. In such a camera, the diaphragm device 10 can accurately adjust the switch position in accordance with the step of the drive motor, so that high-precision driving can be realized.

DESCRIPTION OF SYMBOLS 101 Diaphragm blade 102 Rotating ring 103 Cam plate 104 Driving force transmission part 105 Annular ground plate 106 Gear 107 Sensor 108 Storage case

Claims (5)

A cam plate in which a cam groove is formed;
A base plate covering the cam plate;
A diaphragm blade disposed between the cam plate and the base plate;
A rotating ring disposed between the cam plate and the base plate for driving the diaphragm blades;
A motor for driving the rotating ring;
A sensor attached to the base plate and detecting an open position of the diaphragm blades,
A gear tooth profile that meshes with each other is formed on each mounting surface of the sensor and the ground plane.   2. The light amount adjusting device according to claim 1, wherein the gear tooth profile portion has an interval of one tooth that is the same as an amount of movement of the rotating ring in one step of driving the motor.   The light quantity adjusting device according to claim 1, wherein the sensor includes a photo interrupter and a case for housing the photo interrupter, and the gear tooth profile is formed in the case.   A rotary ring for driving the diaphragm blades is rotatably disposed between the cam plate and the base plate, the rotary ring is driven by a motor, and a sensor for detecting a rotational position of the rotary ring is provided on the base plate, and the sensor A gear tooth profile portion is formed on the surface where the base plate and the ground plate meet.   An optical apparatus comprising the light amount adjusting device according to any one of claims 1 to 4.

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