JP2006243668A - Zoom lens device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens device capable of correctly detecting a zoom position. <P>SOLUTION: In the zoom lens device 10, a comb-teeth-like member 50 is disposed in a lens frame 36. The comb-teeth-like member 50 is disposed such that many teeth are arranged along a photographic optical axis P. In addition, a photo-interrupter 52 is mounted in the lens frame 46 such that a light emitting element and a light receiving element are disposed opposite to each other, with the teeth of the comb-teeth-like member 50 between them. Accordingly, when the lens frame 36 is moved relative to the lens frame 46 toward the photographic optical axis P, the light receiving element of the photo-interrupter 52 alternately outputs ON and OFF signals. The ON signals are counted by a pulse counter 54. The result of counting the ON signals, namely the number of pulses, is outputted to a CPU 56. The CPU 56 calculates the present focal distance based upon the number of pulses, etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a zoom lens device, and more particularly to a zoom lens device capable of detecting a current zoom position (focal length) due to movement of a zoom lens.

  Japanese Patent Application Laid-Open No. 2004-133867 discloses a retractable extension type zoom lens device that is retracted into a camera body and is extended forward when in use.

  In this zoom lens apparatus, the focal length of the zoom lens is adjusted by moving the first moving lens frame and the second moving lens frame back and forth with respect to the optical axis by a moving mechanism such as a cam cylinder. It is detected by a code plate fixed to the outer periphery of the rear end of the cam ring and a brush that is always in sliding contact with the code plate. That is, conductive lands and non-conductive lands are formed on the code plate, and the brush has one common terminal and three terminals. A “0” signal is extracted when a predetermined terminal of these terminals is in contact with the conductive land of the code board, and a “1” signal is extracted when there is no contact, and these signals are combined. Thus, the rotation position of the cam ring is detected, and the current focal length (zoom position) of the zoom lens is detected.

As another zoom position detection device, a rotary blade having a plurality of blades is attached to a part of a reduction gear of a zoom motor that drives a zoom lens, and a light projecting element and a light receiving element are opposed to each other with the rotary blade interposed therebetween. There is known an apparatus provided with a photo interrupter arranged. This zoom position detection device counts pulse signals output from the photo interrupter, and detects the current focal length (zoom position) of the zoom lens based on the counted number of pulses.
Japanese Utility Model Publication No. 6-18327

  However, in the conventional zoom lens device using a detection device comprising a rotating blade and a photo interrupter as a focal length detection means, the detection device and the actual lens are connected via a plurality of members such as a gear and a rotation cam. Therefore, it is necessary to cancel mechanical backlash such as gear backlash and backlash of the rotating cam, and even if cancelled, there is a problem that an accurate zoom position cannot be detected due to the load. It was.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a zoom lens device capable of accurately detecting a zoom position.

  According to a first aspect of the present invention, there is provided a zoom lens device that changes a focal length by relatively moving the first moving lens frame and the second moving lens frame in the optical axis direction in order to achieve the object. A scale provided on the first moving lens frame; a sensor provided on the second moving lens frame and moved relative to the scale to read position information of the scale; and the position output from the sensor And a calculation means for calculating the current focal length based on the information.

  According to the first aspect of the present invention, the scale is directly attached to the first moving lens frame for adjusting the focal length without using an indirect detection method of detecting the moving position of the zoom lens via the gear or the cam barrel. At the same time, the sensor is directly attached to the second moving lens frame, and the calculation means calculates the current focal length based on the scale position information output from the sensor. That is, according to the present invention, since the moving position of the zoom lens is detected by a direct detection method using a scale and a sensor directly attached to the lens frame, the zoom position can be accurately detected.

  According to a second aspect of the present invention, in the first aspect of the present invention, the scale is a comb-like member, and the sensor is a light emitting / receiving element provided on both sides of the comb-like member. It is characterized by being.

  According to the second aspect of the present invention, when the first moving lens frame and the second moving lens frame move relatively, a pulse signal is output from the light receiving element of the light projecting light receiving element. Therefore, the pulse signal is counted, and the calculation means calculates the current focal length based on the counted number of pulses.

  According to a third aspect of the present invention, in the first aspect of the present invention, the scale is a magnet, and the sensor is a Hall element.

  According to the third aspect of the present invention, when the first moving lens frame and the second moving lens frame move relative to each other, the output voltage from the Hall element changes according to the moving position. Therefore, the calculation means calculates the current focal length based on the output voltage from the Hall element.

  According to the zoom lens device of the present invention, the scale is directly attached to the first moving lens frame for adjusting the focal length, the sensor is directly attached to the second moving lens frame, and the position information of the scale output from the sensor is obtained. Based on this, the calculation means calculates the current focal length, so that the zoom position can be accurately detected.

  A preferred embodiment of a zoom lens apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view illustrating a configuration of a zoom lens device 10 according to the first embodiment. The zoom lens apparatus 10 shown in the figure includes a first lens group 12 that is a front lens, a second lens group 14 that is a variator lens of the zoom lens, a third lens group 16, and a fourth lens group 18 that is a focus lens. The zoom lens apparatus has a four-group lens configuration, and a diaphragm 15 is disposed between the second group lens 14 and the third group lens 16. The zoom lens device 10 also has a fixed lens barrel 20, a movable lens barrel 22, and a cam barrel 24, and a mounting frame for a solid-state image sensor (not shown) at the rear end (right side in FIG. 1) of the fixed lens barrel. 25 is formed.

  The fixed lens barrel 20 is housed and fixed in a camera body (not shown), and a cam cylinder 24 is provided therein so as to be rotatable about the photographing optical axis P. Further, a plurality of rectilinear grooves 26, 26... Formed in parallel with the photographing optical axis P are formed on the inner peripheral surface of the fixed lens barrel 20, and the movable lens barrel 22 is formed in these rectilinear grooves 26, 26. Are formed on the outer peripheral surface of the slidably fitted slidably fitted portions. Therefore, the movable lens barrel 22 is moved in the direction of the photographic optical axis P along the rectilinear grooves 26, 26... To project from the position stored in the fixed lens barrel 20 and the fixed lens barrel 20 as shown in FIG. It is reciprocated within the range of the position. A lens frame 30 holding the first group lens 12 is fixed to the front end portion (left side of FIG. 1: subject side) of the movable barrel 22.

  The cam cylinder 24 is rotated in the normal rotation direction and the reverse rotation direction about the photographing optical axis P by transmitting power from a zoom motor (not shown). On the outer peripheral surface of the cam barrel 24, a cam groove 32 for storing and feeding the movable lens barrel 22 is formed, and a cam follower 34 of the movable lens barrel 22 is fitted into the cam groove 32. Accordingly, when the cam barrel 24 is rotated by the driving force of the zoom motor, the movable lens barrel 22 is in a state in which the rotation is restricted by the rectilinear groove 26 of the fixed lens barrel 20, and the photographing optical axis P of the cam groove 32. It is moved within the range along the movement path of the direction component.

  The second group lens 14 is held by a lens frame (first moving lens frame) 36. A guide hole 38 is formed in the lens frame 36 in parallel with the photographing optical axis P, and a guide bar 40 is inserted into the guide hole 38. The guide bar 40 has a base end fixed to the fixed barrel 20 and extends in parallel with the photographing optical axis P. Accordingly, the lens frame 36 is reciprocated within the range indicated by the solid line and the position indicated by the two-dot chain line by being moved along the guide bar 40 in the photographing optical axis P direction. The focal length is adjusted by this moving operation.

  A cam groove 42 for moving the lens frame 36 is formed on the inner peripheral surface of the cam cylinder 24, and a cam follower 44 of the lens frame 36 is fitted in the cam groove 42. Therefore, when the cam cylinder 24 is rotated by the driving force of the zoom motor, the lens frame 36 moves along the movement locus of the component in the direction of the photographing optical axis P of the cam groove 42 while the rotation of the lens frame 36 is restricted by the guide bar 40. Along the range.

  The third lens group 16 is held by a lens frame (second moving lens frame) 46. The lens frame 46 is fixed to the fixed barrel 20 by a fixing member (not shown), and thus the third group lens 16 functions as a relay lens. When the third lens group 16 is made to function as a compensator lens, it is supported by a guide bar so as to be movable in the direction of the photographing optical axis P as well as the second lens group 14 which is a variator lens, and dedicated to the cam cylinder 24. The cam groove is formed and moved along the movement locus of the photographic optical axis P direction component of the cam groove, and the focus shift due to the movement of the second group lens 14 is corrected. Therefore, the lens frame 36 and the lens frame 46 move relatively.

  The fourth lens group 18 that is a focus lens is held by a lens frame 48. The lens frame 48 is movably supported along the photographic optical axis P by a movement support member (not shown), and is moved along the photographic optical axis P by a driving force from a focus motor (not shown). Focus is achieved by this action.

  Incidentally, in the zoom lens device 10 according to the embodiment, the lens frame 36 is provided with a comb-like member (scale) 50. The comb-like member 50 is arranged such that a large number of teeth are along the photographing optical axis P. The lens frame 46 is provided with a photo interrupter (sensor) 52 in which a light projecting element and a light receiving element are opposed to each other with the teeth of the comb-like member 50 interposed therebetween. Therefore, when the lens frame 36 moves in the direction of the photographing optical axis P with respect to the lens frame 46, ON / OFF signals are alternately output from the light receiving element of the photo interrupter 52, and the ON signal is counted by the pulse counter 54 shown in FIG. Is done.

  The counted ON signal, that is, the number of pulses (scale position information) is output to a CPU (calculation means) 56 of a camera (not shown). The CPU 56 outputs zoom direction information in the tele direction or the wide direction from a zoom controller such as a zoom seesaw lever provided in the camera. Further, the CPU 56 stores a focal length based on the number of pulses. Therefore, the CPU 56 calculates the current focal length (zoom position) based on the number of pulses from the pulse counter 54 and the zoom direction information, and displays the result on a display device such as an electronic viewfinder of the camera or an LCD.

  Thus, according to the zoom lens device 10 of the embodiment, the lens frame of the variator lens 14 that adjusts the focal length without using an indirect detection method of detecting the movement position of the zoom lens via the gear or the cam cylinder. The comb-like member 50 is directly attached to 36, and the photo interrupter 52 is directly attached to the lens frame 46, and the CPU 56 calculates the current focal length based on the number of pulses output from the photo interrupter 52 and zoom direction information.

  That is, the zoom lens apparatus 10 detects the moving position of the second lens group (zoom lens) 14 by a direct detection method using the comb-like member 50 and the photo interrupter 52 that are directly attached to the lens frames 36 and 46. The zoom position can be accurately detected.

  In the embodiment, the comb-like member 50 is attached to the lens frame 36, and the photo interrupter 52 is attached to the lens frame 46. However, the present invention is not limited to this, and the photo interrupter 52 is attached to the lens frame 36. The comb-like member 50 may be attached to the lens frame 46.

  FIG. 3 is a cross-sectional view of the zoom lens device 60 according to the second embodiment. The same or similar members as those in the zoom lens device 10 shown in FIG. .

  According to the zoom lens device 60, a magnet (scale) 62 is attached to the lens frame 36, and a hall element (sensor) 64 is attached to the lens frame 46. The magnet 62 is disposed along the photographing optical axis P, and the hall element 64 is disposed to face the magnet 62. Accordingly, when the lens frame 36 moves in the direction of the photographing optical axis P with respect to the lens frame 46, the amount of magnetic flux received by the Hall element 64 changes, so that a voltage corresponding to the movement position of the lens frame 46 is generated from the Hall element 64. Is output. This voltage is amplified with a predetermined gain by the amplifier circuit 66 shown in FIG. 4, and the amplified voltage is measured by the digital voltmeter 68.

  The measured voltage (scale position information) is output to a CPU (calculation means) 70 of a camera (not shown). The CPU 70 stores a focal length based on the voltage. Therefore, the CPU 70 calculates the current focal length (zoom position) based on the amplified voltage, and displays the result on a display device such as an electronic viewfinder of the camera or an LCD.

  Thus, according to the zoom lens device 60 of the embodiment, the magnet 62 is directly attached to the lens frame 36 of the variator lens 14 for adjusting the focal length, and the Hall element 64 is directly attached to the lens frame 46. CPU 70 calculates the current focal length based on the output voltage.

  That is, the zoom lens device 60 detects the moving position of the second lens group (zoom lens) 14 by a direct detection method using the magnet 62 and the Hall element 64 that are directly attached to the lens frames 36 and 46. It can be detected accurately.

  In the embodiment, the magnet 62 is attached to the lens frame 36 and the hall element 64 is attached to the lens frame 46. However, the present invention is not limited to this, and the hall element 64 is attached to the lens frame 36. You may attach the magnet 62 to.

  In the embodiment, the comb-like member 50 and the magnet 62 are illustrated as the scale, and the photo interrupter 52 and the Hall element 64 are illustrated as the sensors. However, the present invention is not limited thereto, and the movement of the lens 36 is directly performed. For example, a linear scale that can be detected may be used.

Sectional drawing of the zoom lens apparatus of 1st Embodiment The block diagram which showed the control system of the zoom lens apparatus shown in FIG. Sectional drawing of the zoom lens apparatus of 2nd Embodiment The block diagram which showed the control system of the zoom lens apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Zoom lens apparatus, 12 ... 1st group lens, 14 ... 2nd group lens, 16 ... 3rd group lens, 18 ... 4th lens, 20 ... Fixed lens barrel, 22 ... Moving lens barrel, 24 ... Cam barrel, 36 ... Lens frame, 46 ... Lens frame, 50 ... Comb-like member, 52 ... Photo interrupter, 54 ... Pulse counter, 56 ... CPU, 60 ... Zoom lens device, 62 ... Magnet, 64 ... Hall element, 66 ... Amplifier circuit 68 ... Digital voltmeter, 70 ... CPU

Claims (3)

In the zoom lens device that changes the focal length by relatively moving the first moving lens frame and the second moving lens frame in the optical axis direction,
A scale provided on the first moving lens frame;
A sensor provided on the second moving lens frame and moved relative to the scale to read position information of the scale;
A calculation means for calculating a current focal length based on the position information output from the sensor;
A zoom lens device comprising: The scale is a comb-like member,
2. The zoom lens apparatus according to claim 1, wherein the sensor is a light projecting / receiving element provided on both sides of the comb-like member. The scale is a magnet;
The zoom lens apparatus according to claim 1, wherein the sensor is a Hall element.

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