JP2013003351A - Optical element position detector, lens barrel and image pickup apparatus - Google Patents

Abstract

An optical element position detection device is provided that detects the position of an optical element with high accuracy with a simple configuration.
An optical element position detecting device generates a sinusoidal magnetic flux, moves in the optical axis direction of the optical element integrally with the optical element, and the sinusoidal magnetic flux generated by the multipolar magnet. The first detection unit for detecting two kinds of sinusoidal signals having a predetermined phase difference and the movement range of the multipolar magnet are divided into n (n is an integer of 2 or more), and the multipolar magnet exists. Calculating a periodic position signal that fluctuates at a constant period according to the movement of the optical element from the two types of sinusoidal signals detected by the first detection unit, A conversion unit that converts a periodic position signal into a continuous position signal that continuously varies according to the movement of the optical element based on the divided areas detected by the second detection unit.
[Selection] Figure 2

Description

  The present invention relates to an optical element position detection device, a lens barrel, and an imaging device.

  Conventionally, in an imaging apparatus, a zooming movable lens and a focusing movable lens are arranged inside a lens barrel for a zoom function and an autofocus function. Further, a position detection device for detecting the positions of these movable lenses is provided in the lens barrel (see, for example, Patent Document 1).

JP 2009-169202 A

  However, in the above-mentioned patent document 1, it is necessary to detect a periodic detection signal whose peak value changes according to the movement amount of the lens by the sensor unit. For this reason, when using, for example, the strength of the magnetic field generated by the position detection magnet as the detection signal, various measures are required so that the peak value of the magnetic field strength changes according to the amount of movement of the lens. There is a risk of complications and deterioration of space efficiency.

  Therefore, the present invention has been made in view of the above problems, and provides an optical element position detection device, a lens barrel, and an imaging device that can detect the position of an optical element with high accuracy with a simple configuration. For the purpose.

  The optical element position detection device of the present invention generates a sinusoidal magnetic flux, moves in the optical axis direction of the optical element integrally with the optical element (L2), and the multipolar magnet. A first detection unit (112) for detecting two kinds of sinusoidal signals having a predetermined phase difference from the generated sinusoidal magnetic flux, and a movement range of the multipolar magnet is divided into n (n is an integer of 2 or more); A second detection unit (114) for detecting a divided region where the multipolar magnet exists, and two types of sinusoidal signals detected by the first detection unit at a constant period according to the movement of the optical element. A continuous position signal that calculates a periodic position signal that fluctuates, and that continuously changes in accordance with the movement of the optical element, based on the divided area detected by the second detector. An optical element position detection comprising a conversion unit (110) for converting to It is the location.

  In this case, the multipolar magnet used by the first detection unit for detecting the sinusoidal signal and the multipolar magnet detected by the second detection unit may be the same. The two types of sinusoidal signals detected by the first detection unit may have a phase difference of approximately 90 °.

  In the optical element position detection device of the present invention, a substitute tool (314) provided in place of the optical element, and a position detection device (310) for detecting the position of the substitute tool while moving the substitute tool A generation unit (110) for generating a correction table representing a difference between the position of the substitute tool detected by the position detection device and the position detected by the first detection unit and the second detection unit; A position detection unit (110) that detects the position of the optical element based on the continuous position signal and the correction table may be further provided.

  In this case, the substitute tool is a reflector, and the position detection device can detect the position of the reflector optically and in a non-contact manner.

  The lens barrel of the present invention is a lens barrel provided with the optical element position detection device of the present invention.

  In this case, a correction table for correcting the continuous position signal converted by the conversion unit to a value corresponding to the position of the optical element can be provided. In this case, the correction table may include at least one of a value for correcting the origin of the continuous position signal and a value for correcting the periodic position signal or the linearity of the continuous position signal.

  In the lens barrel of the present invention, the multipolar magnet may constitute a part of a drive unit (LM) that drives the optical element. The lens barrel includes a zoom optical system (L1 to L5), the optical element is a focus lens (L2) constituting at least a part of the zoom optical system, and the conversion unit is The continuous position signal can be converted at the timing of performing the initialization operation of the detection value of the zoom optical system detection unit that detects the position of the zoom optical system.

  The imaging apparatus of the present invention includes the lens barrel (100) of the present invention and an imaging element (238) that converts light received through the lens barrel into an electrical signal.

  In addition, in order to explain the present invention in an easy-to-understand manner, the above description has been made in association with the reference numerals of the drawings representing one embodiment. However, the present invention is not limited to this, and the configuration of an embodiment described later is provided. May be modified as appropriate, or at least a part thereof may be replaced with another component. Further, the configuration requirements that are not particularly limited with respect to the arrangement are not limited to the arrangement disclosed in the embodiment, and can be arranged at a position where the function can be achieved.

  The optical element position detection device, the lens barrel, and the imaging device of the present invention have an effect that the position of the optical element can be detected with high accuracy with a simple configuration.

It is a figure which shows the structure of the camera which concerns on one Embodiment. It is sectional drawing which shows the state which has a lens-barrel in a wide angle end. It is sectional drawing which shows the state in which the lens barrel was zoomed to the telephoto end. It is a figure for explaining guide bar 30A. It is a figure which shows arrangement | positioning of a linear motor, a Hall sensor, and an origin sensor. It is a figure which shows the structure of a measuring device. It is a figure which shows the relationship between the output of a Hall sensor and an origin sensor, and an absolute position. It is a figure which shows the state which converted FIG. 7 into the continuous position signal. It is a figure for demonstrating linearity correction | amendment. Fig.10 (a)-FIG.10 (c) are the figures (the 1) which show the Lissajous curve of A phase output and B phase output. FIG. 11A to FIG. 11D are diagrams (No. 2) illustrating Lissajous curves of the A-phase output and the B-phase output. FIGS. 12A and 12B are diagrams (No. 3) illustrating Lissajous curves of the A-phase output and the B-phase output. It is a figure for demonstrating the indefinite area | region of the output value of an origin sensor. It is a figure for demonstrating the case where there are two or more discontinuous points in the output of a hall sensor.

  Hereinafter, a camera according to an embodiment and a lens barrel included in the camera will be described in detail with reference to FIGS.

  FIG. 1 schematically shows a camera 500 according to the present embodiment. As shown in FIG. 1, the camera 500 includes an imaging unit 200 and a lens barrel 100.

  The imaging unit 200 includes a housing 210, an optical system including a primary mirror 212, a pentaprism 214, and an eyepiece optical system 216 housed in the housing 210, a focus detection device 230, a shutter 234, and an image sensor 238. And a main LCD 240 and a main control unit 250.

  In the state of FIG. 1, the main mirror 212 guides most of the incident light incident from the lens barrel 100 to a focusing screen 222 disposed above. The focusing screen 222 is disposed at a focus position of the optical system in the lens barrel 100 and forms an image formed by the optical system in the lens barrel 100.

  The pentaprism 214 reflects the image formed on the focusing screen 222 and then guides it to the eyepiece optical system 216 via the half mirror 224. Thereby, the eyepiece optical system 216 can observe the image on the focusing screen 222 as a normal image. In this case, the half mirror 224 superimposes a display image formed on the finder LCD 226 indicating the shooting conditions, setting conditions, and the like on the image of the focusing screen 222. Accordingly, at the exit end of the eyepiece optical system 216, it is possible to observe a state in which the image on the focusing screen 222 and the image on the viewfinder LCD 226 are superimposed. A part of the light emitted from the pentaprism 214 is guided to the photometry unit 228, and the photometry unit 228 measures the intensity of the incident light, its distribution, and the like.

  The focus detection device 230 uses the light transmitted through the primary mirror 212 and reflected by the secondary mirror 232 provided on the back side of the primary mirror 212 to adjust the focus of the optical system in the lens barrel 100 ( Detect focus state. Note that the primary mirror 212 and the secondary mirror 232 are raised to a position indicated by a broken line in FIG. 1 so as to be retracted from the optical path of incident light incident from the lens barrel 100 at the time of photographing.

  The shutter 234 is disposed behind the primary mirror 212 (behind the optical path of incident light incident from the lens barrel 100), and performs an opening operation in conjunction with the ascending operation of the primary mirror 212 and the secondary mirror 232 at the time of shooting. Do. In a state where the shutter 234 is opened, incident light from the lens barrel 100 enters the image sensor 238 via the optical filter 236. The image sensor 238 converts an image formed by incident light into an electrical signal.

  The main LCD 240 has a display screen portion exposed to the outside of the housing 210. On the display screen of the main LCD 240, various setting information and the like in the imaging unit 200 are displayed in addition to the video (captured video) formed on the imaging device 238.

  The main control unit 250 comprehensively controls various operations of the respective units. Further, the main control unit 250 refers to the operation amount of the optical system in the lens barrel 100 to display that the in-focus state is on the finder LCD 226 (focus aid).

  Next, the configuration of the lens barrel 100 will be described in detail with reference to FIGS.

  2 and 3 are cross-sectional views of the lens barrel 100. FIG. Among these, FIG. 2 shows a state in which the lens barrel 100 is at the wide-angle end, and FIG. 3 shows a state in which the lens barrel 100 is zoomed to the telephoto end. As shown in these drawings, the lens barrel 100 includes a first group lens L1, a second group lens L2, a third group lens L3, a fourth group lens L4, and a fifth group lens L5 arranged on a common optical axis AX. . In the following description, the first group lens L1 side in the optical axis AX direction will be described as the front side, and the fifth group lens L5 side as the rear side.

  As shown in FIGS. 2 and 3, the lens barrel 100 includes a fixed barrel 10, a first group lens sliding cylinder 11 that holds the first group lens L1, and a second group lens sliding cylinder that holds the second group lens L2. 12, a third group lens sliding cylinder 13 holding the third group lens L3, a fourth group lens sliding cylinder 14 holding the fourth group lens L4, and a fifth group lens sliding cylinder 15 holding the fifth group lens L4. .

  The fixed cylinder 10 is fixed to the imaging unit 200 at the base 10a. In this fixed state, the fixed cylinder 10, that is, the lens barrel 100, is in contact with the imaging unit 200 because the end surface 10 b of the fixed cylinder 10 on the imaging unit 200 side is in close contact with the imaging unit 200 (the casing 210 in FIG. Positioned.

  The first group lens sliding cylinder 11 is connected to a zoom drive cylinder 16 provided inside the first group lens sliding cylinder 11 so as to be interlocked. Specifically, the cam pin 95 implanted in the first group lens sliding cylinder 11 is engaged with a cam groove 16 a formed in the zoom driving cylinder 16.

  On the other hand, the zoom drive cylinder 16 is connected to a zoom operation ring 18 that can freely rotate around the optical axis AX at the outermost periphery of the lens barrel 100. Specifically, a driving force transmission pin 19 projecting outward from the zoom driving cylinder 16 is engaged with an operation groove 18 a parallel to the optical axis AX formed on the inner surface of the zoom operation ring 18. Thereby, the zoom drive cylinder 16 rotates in conjunction with the rotation of the zoom operation ring 18. The zoom operation ring 18 cannot be moved in the front-rear direction, and an anti-slip rubber layer is provided on the outer peripheral surface thereof. The zoom operation ring 18 is rotated by the user during zooming. The rotation amount of the zoom operation ring 18 is detected by a first rotation amount detection sensor 102 provided in the vicinity of the zoom operation ring 18 and transmitted to the lens barrel control unit 110.

  According to the above structure, when the zoom operation ring 18 is rotated, the zoom driving cylinder 16 is rotated by the action of the driving force transmission pin 19, and the first group lens sliding cylinder 11 is moved in the front-rear direction by the action of the rotation and the cam pin 95. It moves in the direction along the optical axis AX. Further, the zoom guide tube 22 moves in the front-rear direction without rotating.

  A cover cylinder 17 is provided between the zoom operation ring 18 and the first group lens sliding cylinder 11. As shown in FIGS. 2 and 3, the cover cylinder 17 moves in the front-rear direction in accordance with the first group lens sliding cylinder 11, and seals between the zoom operation ring 18 and the first group lens sliding cylinder 11. It stops and prevents intrusion of dust into the lens barrel 100.

  As shown in FIG. 2, the second group lens sliding cylinder 12 is provided so as to surround a holding cylinder 24 that holds the second group lens L <b> 2, a holding ring 26 fixed to the holding cylinder 24, and an outer periphery of the holding cylinder 24. Engaging cylinder 28. The holding cylinder 24 and the pressing ring 26 are fixed by screwing or the like, and sandwich the outer edge portion of the second group lens L2. The outer peripheral part of the holding cylinder 24 is a male screw part, and the inner peripheral part of the holding ring 26 is a female screw part that can be screwed into the male screw part of the holding cylinder 24. Positioning of the holding cylinder 24 with respect to the engaging cylinder 28 (positioning in the optical axis AX direction) is performed by bringing the holding cylinder 24 into close contact with the surface 28c of the engaging cylinder 28.

  The engagement cylinder 28 cantileverly supports the two guide bars 30A and 30B. The guide bars 30A and 30B are arranged at symmetrical positions with respect to the optical axis AX. As shown in FIGS. 2 and 3, the guide bar 30A is inserted into the through holes 10g and 10h formed in the protrusions 10c and 10d of the fixed cylinder 10, and is slidable with respect to the through holes 10g and 10h. It has become. Further, the guide bar 30B is engaged with U-shaped grooves 10i and 10j formed in the protrusions 10e and 10f of the fixed cylinder 10, and the guide bar 30B is slidable along the U-shaped grooves 10i and 10j. It is in a state.

  As a material of the guide bar 30B, a high-strength and lightweight material such as stainless steel can be used. On the other hand, the guide bar 30A has a cylindrical multipolar magnet. As shown in FIG. 4, the multipolar magnet is obtained by connecting (for example, bonding) a plurality of columnar permanent magnets 31 with the same poles attached to each other, and generates a sinusoidal magnetic flux. The guide bar 30A may constitute a multipolar magnet by filling permanent magnets in a cylindrical pipe. However, the pipe must be made of a material that does not block the magnetic field generated by the permanent magnet. Note that the engagement cylinder 28 and the guide bars 30A and 30B are fixed through a process such as bonding or press-fitting.

  Near the front end of the guide bar 30A (end on the second group lens L2 side), a stator 40 having a three-phase coil wound inside is provided. The three-phase coil is set so that the pitch between the phase coils (in the optical axis AX direction) is λ / 6, where λ is the pitch between the same poles of the two permanent magnets 31 constituting the guide bar 30A. A coil unit in which coils are arranged is three-phase connected.

  The stator 40 is fixed to a part of the fixed cylinder 10 (in FIG. 2 and FIG. 3, a protruding portion 10c). A current is supplied to the stator 40 under the instruction of the lens barrel control unit 110. Due to the electromagnetic interaction between the current flowing through the stator 40 and the magnetic field generated by the guide bar 30A, the guide bar 30A has A force in the direction (front-rear direction) along the optical axis AX acts. Therefore, in the present embodiment, the linear motor LM that drives the second group lens L2 in the optical axis AX direction is realized by the stator 40 and the guide bar 30A (see FIG. 5). Here, the second group lens L2 and the members (24, 26, 28) for holding the second group lens L2 are arranged along the optical axis AX direction by the guide bar 30A being guided by the through holes 10g, 10h of the protrusions 10c, 10d. Move. Further, the movement of the guide bar 30B is restricted by the U-shaped grooves 10i and 10j of the protrusions 10e and 10f, so that the guide bar 30A of the second group lens L2 and the members (24, 26, 28) for holding the second group lens L2 Rotation around the center is suppressed (stabilized).

  Hall sensors 112A and 112B and an origin sensor 114 are provided in the vicinity of the guide bar 30A, as shown in FIGS. The specific configurations and functions of the hall sensors 112A and 112B and the origin sensor 114 will be described later.

  The third lens group sliding cylinder 13, the fourth lens group sliding cylinder 14, and the fifth lens group sliding cylinder 15 are moved in the front-rear direction (optical axis AX direction) by a drive mechanism (not shown) under the instruction of the lens barrel control unit 110. Driven by.

  As shown in FIGS. 2 and 3, a focus ring 37 is provided on the outer peripheral portion of the fixed cylinder 10. Near the focus ring 37, a second rotation amount detection sensor 104 for detecting the rotation amount of the focus ring 37 is provided. The detection result of the second rotation amount detection sensor 104 is transmitted to the lens barrel control unit 110.

  The lens barrel control unit 110 acquires detection results (rotation amount signals and movement amount signals) transmitted by the first and second rotation amount detection sensors 102 and 104, the hall sensors 112A and 112B, and the origin sensor 114, and the detection results. Based on this, the operation of the linear motor LM is controlled.

  Next, in the lens barrel 100 of the present embodiment, the first group lens L1 to L5 when the zoom operation is performed (zooming) and the first group lens when the focusing is performed (focusing). The movement operation of the L1 to 5th group lens L5 will be described.

  First, the movement operation of each lens during zooming will be described. Here, the operation from the state in which the lens barrel 100 is at the wide-angle end (FIG. 2) to the zooming to the telephoto end (FIG. 3) will be described.

  When the zoom operation ring 18 is rotated by the user from the state of FIG. 2, as described above, the first group lens L1 moves in the forward direction. The rotation amount of the zoom operation ring 18 is detected by the first rotation amount detection sensor 102 and transmitted to the lens barrel control unit 110. The lens barrel control unit 110 operates the linear motor LM based on the detection result (rotation amount signal) of the first rotation amount detection sensor 102 to move the second lens group L2 forward by an amount corresponding to the rotation amount signal. Let In addition, the lens barrel control unit 110 controls a driving unit (not shown) to move the third to fifth group lenses L3 to L5 forward by an amount corresponding to the rotation amount signal.

  Thus, during zooming, each of the first to fifth group lenses L1 to L5 moves forward by a different distance (or the same distance) in accordance with the rotation operation of the zoom operation ring 18, and The interval changes.

  On the other hand, during focusing, when the focus ring 37 is rotated by the user, the detection result (rotation amount signal) of the second rotation amount detection sensor 104 is transmitted to the lens barrel control unit 110. Then, the lens barrel control unit 110 operates the linear motor LM by an amount corresponding to the rotation signal, and moves the second group lens L2 in the front-rear direction. When adopting autofocus, the lens barrel control unit 110 acquires the detection result of the focus detection device 230 of the imaging unit 200. And the lens-barrel control part 110 operates the linear motor LM based on the acquired detection result.

  Next, the hall sensors 112A and 112B and the origin sensor 114 provided near the guide bar 30A will be described in detail with reference to FIGS.

  Each of the hall sensors 112A and 112B includes a hall element that detects a sinusoidal magnetic flux emitted from the guide bar 30A and outputs a voltage. The change in voltage output of each Hall element changes sinusoidally according to the position.

Here, the outputs of the hall sensors 112A and 112B are respectively referred to as an A phase output and a B phase output. If the phase difference between the A-phase output and the B-phase output is α, the phase difference α is determined by the relative distance between the Hall sensors 112A and 112B. When the amplitude is K, the average value of the output is Vc, and the current position is X, each output is expressed by the following equations (1) and (2) using the pitch λ between the same poles of two permanent magnets. The
A phase output = Vc + Ksin (2π × X / λ) (1)
B phase output = Vc + Ksin (2π × X / λ + α) (2)
Since the phase difference α is 90 ° when the relative distance between the Hall sensors 112A and 112B is set to λ / 4, in this embodiment, the Hall sensors 112A and 112B are installed at relative positions where this relationship is established. ing. In this case, the above equation (2) can be expressed as the following equation (2-1).
B phase output = Vc + Ksin (2π × X / λ + 90 °)
= Vc + Kcos (2π × X / λ) (2-1)

Summarizing these equations, the current position X can be calculated from the following equation (3).
X = (λ / 2π) × tan ⁻¹ {(A phase output−Vc) / (B phase output−Vc)}
... (3)
From the above equation (3), it can be said that the current position X is a periodic position signal that fluctuates at a constant period (see the upper part of FIG. 7).

  Returning to FIG. 2, the origin sensor 114 is a sensor that includes a photo interrupter, divides the movement range of the guide bar 30 </ b> A into two, and detects a divided region where the guide bar 30 </ b> A exists. That is, the origin sensor 114 detects whether the guide bar 30A is located at a position (divided area) facing the origin sensor 114 or a position (divided area) not facing the origin sensor 114 (divided area). Sensor. While the origin sensor 114 is in a state of facing the guide bar 30A (for example, while being in the state as shown in FIG. 2), the origin sensor 114 gives an H (High) value as shown in the lower part of FIG. Output. On the other hand, while the origin sensor 114 is not opposed to the guide bar 30A (for example, while being in the state as shown in FIG. 3), the L (Low) value as shown in the lower part of FIG. Output for. The logic of H / L shown here may be opposite to the logic of the circuit to be detected. As long as the output is neither the H value nor the L value, it means that the end of the guide bar 30A faces the origin sensor 114 as shown in FIG.

  By the way, it is unclear to which position in the absolute coordinate system of the second group lens this position corresponds only to the current position X calculated from the above equation (3). Therefore, the current position X of the second group lens L2 and the output of the origin sensor 114 need to correspond to the absolute position as shown in FIG. For this reason, in the present embodiment, for example, when the lens barrel 100 is assembled, the current position X of the second group lens L2, the output of the origin sensor 114, and the absolute position are measured using a measuring apparatus 300 as shown in FIG. Need to be associated with each other. Note that the configuration and the like of the measurement apparatus 300 in FIG. 6 will be described later.

  Here, as shown in FIG. 7, the current position X changes periodically every λ and is discontinuous. Thus, when the current position X changes discontinuously, even if the lens barrel control unit 110 calculates the current position X, a plurality of absolute positions are calculated from the current position X. For this reason, the lens barrel control unit 110 uses the output value of the origin sensor 114 to perform conversion so that the current position X takes a continuous value. As a premise for conversion, it is assumed that the relative positions of the hall sensor 112 and the origin sensor 114 are known in advance.

  FIG. 8 shows an example of continuation based on the output value of the origin sensor 114. For example, when the relationship between the current position X and the output value of the origin sensor 114 is as shown in FIG. 7, the lens barrel control unit 110 causes the discontinuous point at the portion where the output value of the origin sensor 114 is H (High). When is found, it is added to the calculated value by the amount shifted at the discontinuous point (shifted upward). On the other hand, when a discontinuous point is found in the portion where the output value of the origin sensor 114 is L (Low), the lens barrel control unit 110 subtracts from the calculated value by the amount shifted at the discontinuous point (shifts downward). ). In this way, a continuous position as shown in the upper part of FIG. 8 can be obtained. Note that the logic of the origin sensor and the shift direction at the discontinuous points may be reversed depending on the configuration of the detection circuit.

  As described above, the lens barrel control unit 110 of the present embodiment has a periodic position (currently fluctuating) with a constant period according to the movement of the second lens group L2 from the two types of sinusoidal signals detected by the Hall sensors 112A and 112B. Position X) and converting the periodic position into a continuous position that continuously varies according to the movement of the second group lens L2 based on the output value (H or L) of the origin sensor 114. Is going.

  The measuring apparatus 300 in FIG. 6 includes a laser displacement meter 310 and a fixed base 312 that fixes the positional relationship of the fixed cylinder 10 with respect to the laser displacement meter 310. When the fixed cylinder 10 is fixed to the fixed base 312, the first group lens L1 and its peripheral members (for example, the first group lens sliding cylinder 11 and the zoom operation ring 18) are not attached to the fixed cylinder 10. Further, it is assumed that a reflecting plate (alternative tool) 314 capable of reflecting the laser light emitted from the laser displacement meter 310 is attached instead of the second group lens L2. Here, it is assumed that the reflection plate 314 is held by a reflection plate holding cylinder having the same function as the holding cylinder 24 holding the second group lens L2 shown in FIGS. That is, the reflection plate holding cylinder has a male threaded portion on the outer periphery thereof, like the retaining cylinder 24, and the male threaded part is screwed into the female threaded part of the engaging cylinder 28. . Positioning of the reflecting plate holding cylinder with respect to the engaging cylinder 28 (positioning in the direction of the optical axis AX) is performed by being in close contact with the surface 28c of the engaging cylinder 28.

  The origin position of the fixed cylinder 10 is determined with reference to the base 10a. However, the origin of the continuous position calculated above does not coincide with the absolute position of the fixed cylinder 10, and the mounting positions of the hall sensors 112A and 112B are fixed by the fixed cylinder 10. And a difference occurs in the relative position between the base 10a.

  Therefore, in the present embodiment, the difference between the calculated origin position of the continuous position and the origin position determined from the base portion 10a of the fixed cylinder 10 is obtained in advance using the measuring device 300. The obtained difference is stored as an offset value of the origin position.

  In the above description, the A-phase output and the B-phase output are expressed as sine wave (cosine wave) voltages having a constant DC offset, but the phase difference α depends on the mounting position of the Hall sensors 112A and 112B. May be shifted from 90 °, may be distorted, and there may be a difference between the A-phase output and the B-phase output with respect to the offset value. In such a case, the Lissajous waveform obtained by plotting the A-phase output and the B-phase output in a rectangular coordinate plane is not a perfect circle, but a distorted circle. In this state, as shown in FIG. 9, there is an error between the absolute position (illustrated by a broken line) calculated on the assumption that the waveform is a perfect Lissajous waveform and the absolute position obtained from the current position X (illustrated by a solid line). May occur.

  Therefore, in the present embodiment, for each fixed cylinder 10, the difference between the output of the measurement device 300 at each position and the absolute position calculated on the assumption that it is a perfect circle Lissajous waveform is measured in advance, and the difference is calculated. These are stored in the lens barrel control unit 110 as a linearity correction table for each calculated absolute position.

  As a specific working method, when the fixed cylinder 10 is fixed to the measuring device 300, the operator instructs the lens barrel control unit 110 from the outside to move the reflecting plate 314 within the lens movable range. . Based on this instruction, the lens barrel control unit 110 drives the linear motor LM to move the reflecting plate 314 within the lens movable range. The lens barrel control unit 110 measures the laser light reflected by the reflecting plate 314 with the laser displacement meter 310 while the reflecting plate 314 is moving, and measures the absolute position of the reflecting plate 314. In other words, the lens barrel control unit 110 uses the laser displacement meter 310 to measure the absolute position of the reflector 314 optically and non-contactingly. In addition, the lens barrel controller 110 acquires the outputs of the hall sensors 112A and 112B and the origin sensor 114 corresponding to the absolute position while measuring the absolute position. FIG. 7 shows the output results (current position X) of the hall sensors 112A and 112B and the origin sensor 114 corresponding to the absolute position.

  The lens barrel control unit 110 calculates the absolute position of the current position X calculated using the hall sensors 112A and 112B and the origin sensor 114 by using an offset value for correcting the origin and a linearity correction table. By doing so, it is possible to obtain the absolute position of the second group lens L2 with high accuracy without being affected by the linearity and the origin deviation, and as a result, the position control of the second group lens L2 can be performed with high accuracy.

  In the present embodiment, when the lens barrel 100 is used (mounted on the imaging unit 200 and powered on), the position of the zoom optical system (1 to 5 group lenses) is not shown. The absolute value is obtained by performing the above correction calculation at the timing of initializing the detection value of the sensor, and the shooting distance is calculated using the detected value of the zoom optical system detection unit and the absolute position. Can be. In this way, it is possible to calculate the shooting distance at an appropriate timing. The calculated shooting distance may be displayed on the main LCD or the like of the imaging unit 200, or may be displayed on the display unit provided with a display unit (an index plate or the like) in the lens barrel 100.

  As described above, according to the present embodiment, the guide bar 30A has a multipolar magnet that generates a sinusoidal magnetic flux, moves in the direction of the optical axis AX together with the second group lens L2, and the Hall sensor 112A. 112B detect two types of sinusoidal signals having a phase difference of about 90 ° from the sinusoidal magnetic flux generated by the multipolar magnet. In addition, the origin sensor 114 divides the movement range of the multipolar magnet into two, and detects a divided region where the multipolar magnet exists. Then, the lens barrel control unit 110 calculates a periodic position (current position X) that fluctuates at a constant period according to the movement of the second group lens L2 from the two types of sinusoidal signals detected by the Hall sensors 112A and 112B. Based on the divided area (output value H or L) detected by the origin sensor 114, the current position X is converted into a continuous position (FIG. 8) that continuously varies according to the movement of the second group lens L2. Thereby, in this embodiment, a continuous position can be obtained with a simple configuration, and the position of the second group lens L2 can be detected with high accuracy by using the continuous position.

  In the present embodiment, a multipolar magnet used by the hall sensors 112A and 112B to detect a sine wave signal is provided on the guide bar 30A, and the origin sensor 114 detects the position (divided region) of the guide bar 30A. In this way, the Hall sensors 112A and 112B and the origin sensor 114 perform detection using the same guide bar 30A, thereby enabling highly accurate detection. However, the present invention is not limited to this, and the origin sensor 114 may detect the position (divided region) of the guide bar 30B.

  In the present embodiment, the absolute position of the reflecting plate 314 is measured optically and non-contactively using the laser displacement meter 310 in the measuring apparatus 300, so that the absolute position of the reflecting plate 314 is measured at high speed and with high accuracy. can do.

  In the present embodiment, since the multipolar magnets used for measurement by the Hall sensors 112A and 112B constitute a part of the linear motor LM that drives the second group lens L2, the measurement is performed separately from the linear motor LM. There is no need to provide a multipolar magnet. As a result, it is possible to improve space efficiency and reduce the number of parts.

  In the above embodiment, the case where the phase difference between the two types of sinusoidal signals detected by the Hall sensors 112A and 112B is approximately 90 ° has been described, but the present invention is not limited to this. That is, the phase difference of the sine wave signal may be a phase difference that can be used to write a circular, elliptical, or substantially elliptical Lissajous curve using two types of sine wave signals. 10 to 12 show Lissajous curves when the phase difference of the sinusoidal signal is changed. As shown in these figures, when the phase difference is other than 0 ° or 180 °, the Lissajous curve is circular, elliptical, or substantially elliptical. Therefore, any value other than 0 ° or 180 ° can be adopted as the phase difference of the sinusoidal signal.

  In the above embodiment, the case where the output value of the origin sensor 114 is switched from L to H at a certain position as shown in FIG. 7 or the like has been described. However, actually, as shown in FIG. There is a case where there is a region (indefinite region) where is not determined to be either L or H. Considering such a case, the positional relationship between the hall sensors 112A and 112B and the origin sensor 114 is set so that the indeterminate region does not enter the discontinuous point of the current position X as shown in FIG. It is preferable.

  In the above embodiment, the case where one origin sensor 114 is used has been described. However, the present invention is not limited to this. When there are three or more discontinuous points at the current position X, a plurality of origin sensors 114 may be provided to determine the shift amount by a combination of logical output values. For example, as shown in FIG. 14, when there are four discontinuous points, three origin sensors of sensors 1 to 3 are used. In this case, when the output value of the origin sensor at the discontinuous point is LLL (when the LLL continues in the range of the continuous point), the output value of the origin sensor at the discontinuous point is shifted to the minus side twice. In the case of LLH (when changing from LLL to LLH in the range of continuous points), it is shifted once to the-side. Further, when the output value of the origin sensor at the discontinuous point is LHH (when changing from LLH to LHH within the range of the continuous point), no shift is performed, and the output value of the origin sensor at the discontinuous point is HHH ( In the case of changing from LHH to HHH within the range of continuous points), it is shifted once to the minus side. In this way, even when there are a plurality of discontinuous points, it is possible to perform highly accurate position measurement and position control of the second group lens L2.

  In the above embodiment, the case where the guide bar 30A constitutes a part of the linear motor LM and the detection by the hall sensors 112A and 112B is performed using the guide bar 30A has been described. However, the present invention is not limited to this. is not. For example, the guide bar 30B may have a multipolar magnet, similar to the guide bar 30A, and detection by the Hall sensors 112A and 112B may be performed using the multipolar magnet.

  In the above embodiment, the case where the guide bars 30A and 30B are provided in the internal space of the fixed cylinder 10 has been described. However, the present invention is not limited to this, and the guide bars 30A and 30B are provided outside the fixed cylinder 10. May be.

  In the above-described embodiment, the case where the optical element position detection device is a device that detects the position of the second group lens L2 has been described. Good. Further, the optical element position detection device is not limited to the optical element included in the lens barrel attached to the camera, and may be a device that detects the position of the optical element included in another optical device.

  The configuration of the lens barrel of the above embodiment is an example, and the present invention can be applied to other various lens barrels.

  The above-described embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

30A, 30B Guide bar 112A, 112B Hall sensor 114 Origin sensor 110 Lens barrel control unit 100 Lens barrel 238 Image sensor 312 Detection device 314 Reflector 500 Camera L1-L5 1-5 group lens L2 2 group lens LM Linear motor

Claims (11)

A multipolar magnet that generates a sinusoidal magnetic flux and moves in the direction of the optical axis of the optical element together with the optical element;
A first detector that detects two types of sinusoidal signals having a predetermined phase difference from the sinusoidal magnetic flux emitted by the multipole magnet;
A second detection unit that divides the movement range of the multipolar magnet into n (n is an integer of 2 or more) and detects a divided region in which the multipolar magnet exists;
A periodic position signal that fluctuates at a constant period according to the movement of the optical element is calculated from the two types of sinusoidal signals detected by the first detection unit, and the periodic position signal is calculated by the second detection unit. An optical element position detection device comprising: a conversion unit that converts a continuous position signal that continuously fluctuates according to the movement of the optical element, based on the divided area to be detected.   2. The optical element position detection according to claim 1, wherein the multipolar magnet used by the first detection unit to detect a sinusoidal signal and the multipolar magnet detected by the second detection unit are the same. apparatus.   3. The optical element position detection device according to claim 1, wherein the two types of sinusoidal signals detected by the first detection unit have a phase difference of approximately 90 °. An alternative tool provided in place of the optical element;
A position detecting device for detecting the position of the substitute tool while moving the substitute tool;
A generator that generates a correction table that represents a difference between the position of the substitute tool detected by the position detector and the position detected by the first detector and the second detector;
The optical element position according to claim 1, further comprising: a position detection unit that detects a position of the optical element based on the continuous position signal and the correction table. Detection device.   The optical element position detecting device according to claim 4, wherein the substitute tool is a reflecting plate, and the position detecting device detects the position of the reflecting plate optically and non-contactingly.   A lens barrel comprising the optical element position detection device according to any one of claims 1 to 5.   The lens barrel according to claim 6, further comprising a correction table that corrects the continuous position signal converted by the conversion unit to a value corresponding to the position of the optical element.   The correction table includes at least one of a value for correcting an origin of the continuous position signal and a value for correcting linearity of the periodic position signal or the continuous position signal. The lens barrel according to 7.   The lens barrel according to claim 6, wherein the multipolar magnet constitutes a part of a drive unit that drives the optical element. The lens barrel has a zoom optical system,
The optical element is a focus lens constituting at least a part of the zoom optical system;
10. The conversion unit according to claim 6, wherein the conversion unit converts the continuous position signal at a timing at which an operation of initializing a detection value of a zoom optical system detection unit that detects a position of the zoom optical system is performed. The lens barrel according to claim 1. The lens barrel according to any one of claims 6 to 10,
An imaging device comprising: an imaging device that converts light received through the lens barrel into an electrical signal.

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