JP2016018104A - Drive device and lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it is difficult to design miniaturization of a drive device if an existing position detection device is assembled to the drive device.SOLUTION: A drive device is composed of: detected means that has a prescribed pattern periodically formed; detection means that detects a pattern formed by the detected means by intensity in accordance with a distance to the detected means; operation means that allows the detected means and the detection means to relatively operate; distance defining means that defines a distance between the detected means and the detection means in accordance with a position of the detection means relative to the detected means; and computation means that computes the amount of movement of the detection means relative to the detected means on the basis of the number of patterns to be detected by the detection means, and computes the position of the detection means relative to the detected means in accordance with intensity of the pattern to be detected.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a driving device having a position detection function and a lens device including the driving device.

  In a drive device mounted on an electric device such as a digital still camera, a magnetic field change of a magnetic code plate having a magnetic pattern is detected by a magnetic sensor, and the magnetic code plate and the magnetic sensor are relative to each other based on the detected magnetic change. A device that detects a large amount of movement is known. In this type of driving device, in general, only the relative movement amount of a member (for example, a movable member) provided with a magnetic code plate and a member (for example, a fixed member) provided with a magnetic sensor is detected. In order to detect the position of the movable member within the movable range, a position detecting device is separately required. A specific configuration of this type of position detection device is described in Patent Document 1, for example.

  The position detection device described in Patent Document 1 includes a zoom ring. Zooming is performed by moving the lens group in the zoom ring in the direction of the optical axis as the zoom ring rotates. A code plate on which a plurality of conductive patterns are formed is attached to the outer peripheral surface of the zoom ring. A position detection brush is slidably in contact with the code plate. The conductive pattern in contact with the position detection brush changes according to the rotation of the zoom ring. The arithmetic device detects a conductive pattern that contacts the position detection brush, and calculates the position of the lens group in the zoom ring within the movable range based on the detection result.

JP-A-9-61695

  As described above, in order to detect the position of the movable member within the movable range, a position detection device exemplified in Patent Document 1 is required separately from the configuration for detecting the movement amount of the movable member. However, when the position detection device described in Patent Document 1 is incorporated in a driving device, it is necessary to form a large number of conductive patterns for position detection on the code plate, and the area of the code plate increases. The problem of being disadvantaged is pointed out.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a driving device that has a position detection function and is advantageous for downsizing design, and a lens device including the driving device. .

  The driving device according to the present embodiment includes a detection unit in which a predetermined pattern is periodically formed, a detection unit that detects a pattern formed in the detection unit with strength according to the distance from the detection unit, An operating means capable of operating the detected means and the detecting means relatively; a distance defining means for defining a distance between the detected means and the detecting means according to the position of the detecting means relative to the detected means; And calculating means for calculating the amount of movement of the detecting means relative to the detected means based on the number of patterns detected by the means and calculating the position of the detecting means relative to the detected means according to the strength of the detected pattern.

  According to this embodiment, it is possible to calculate the position of the detection means using the detection means and the detected means for detecting the movement amount. That is, since the means for detecting the amount of movement also serves as the means for detecting the position, a driving device that is advantageous for downsizing design is provided.

  In addition, the drive device according to the present embodiment may include a first holding unit that holds the detected unit and a second holding unit that holds the detecting unit. In this case, the operating means moves the detecting means relative to the detected means held on the first holding means by relatively operating the first holding means and the second holding means. The distance defining means includes an urging means for urging the detecting means toward the detected means held on the first holding means, and a first holding means along the moving direction of the detecting means relative to the detected means. A protrusion including at least one step formed on the upper surface, and receiving the detection means urged toward the detection means by the urging means, thereby increasing the distance between the detection means and the detection means. Including those defined at intervals according to the size.

  The protrusion is formed on the first holding unit along the moving direction of the detecting unit in a part of the moving range of the detecting unit with respect to the detected unit, for example. In this case, the detecting means is urged on the detected means by the urging means without passing through the protruding portion in an area where the protruding portion is not formed in the movement range.

  The first holding means is, for example, a cylindrical member that houses and holds a predetermined moving object. In this case, the detected means may be a magnetic code plate that is affixed along the circumferential direction on the outer peripheral surface of the cylindrical member and is magnetized at a predetermined pitch. Further, the detection means may be a magnetic sensor that detects a magnetic field change of the magnetic code plate. In addition, the protrusion is a rib shape standing along the magnetic code plate on the outer peripheral surface of the cylindrical member, and receives the magnetic sensor urged by the urging means, whereby the magnetic code plate and the magnetic sensor The distance may be defined as an interval according to the height.

  Further, the detected means may be a reflection sheet that is affixed along the circumferential direction on the outer peripheral surface of the cylindrical member, and in which a pattern in which the reflection portion and the non-reflection portion are periodically arranged is formed. The detection means may be a photo reflector that detects a pattern formed on the reflection sheet. Further, the protrusion is a rib shape standing on the outer peripheral surface of the cylindrical member along the reflection sheet. By receiving the photo reflector urged by the urging means, the protrusion is formed between the reflection sheet and the photo reflector. It is good also as a structure which prescribes | regulates a distance to the space | interval according to the height.

  The calculation means includes a waveform output means for outputting a different waveform according to the pattern strength of the detected means detected by the detecting means, and a position of the detecting means relative to the detected means based on the waveform output by the waveform output means. It is good also as a structure containing the position calculating means to calculate.

  The waveform output means may include a binarization circuit that converts an analog waveform of the pattern of the detected means detected by the detection means into a binary waveform.

  The binarization circuit may have a configuration in which a threshold for the intensity of the analog waveform is set so that a different binarized waveform is output for each distance between the detected unit and the detecting unit defined by the distance defining unit. Good. In this case, the position calculating means calculates the position of the detecting means relative to the detected means based on the binarized waveform output from the binarizing circuit.

  The binarization circuit is different from the first comparator that always converts the analog waveform into the same binarized waveform regardless of the distance between the detected means and the detection means defined by the distance defining means, and the analog waveform differs for each distance. It is good also as a structure containing the 2nd comparator converted into a binarization waveform. In this case, the calculation means includes a movement amount calculation means for calculating the movement amount of the detection means relative to the detected means based on the first binarized waveform output by the first comparator. Further, the position calculating means calculates the position of the detecting means relative to the detected means based on the second binarized waveform output from the second comparator.

  The binarization circuit may include a third comparator that always converts the analog waveform into the same binarized waveform regardless of the distance between the detected unit and the detection unit defined by the distance defining unit. In this case, the detection means includes a pair of detection sensors that detect the A phase and the B phase whose phases are orthogonal to each other. The second comparator converts the A-phase analog waveform into a second binarized waveform. The third comparator converts the B-phase analog waveform into a third binarized waveform. The position calculating means specifies the position of the detecting means relative to the detected means based on the High / Low of the second binarized waveform at the rise and fall of the third binarized waveform.

  The position calculating means may be configured to determine whether or not the position of the detecting means relative to the detected means is near the end point of the moving range of the detecting means. In this case, when the position of the detection unit relative to the detection unit is determined to be near the end point of the movement range, the operation unit limits the relative operation between the detection unit and the detection unit.

  Further, the driving device of the present embodiment includes a detection brush held by the first holding member and a code plate held by the second holding member and having a predetermined contact pattern formed thereon. Also good. In this case, when the position calculating means determines that the position of the detecting means with respect to the detected means is in the vicinity of the end point of the moving range, the detecting means is based on the contact pattern of the code plate detected by the detecting brush. Specify whether it is located near the other end point. The operating means limits the movement of the detecting means to one end point when the position of the detecting means relative to the detected means is determined to be near one end point, and the position of the detecting means relative to the detected means is set near the other end point. If determined, the movement of the detecting means to the other end point is restricted.

  In addition, the lens apparatus of the present embodiment moves in the optical axis direction in accordance with the relative movement of the detected unit and the detecting unit by the driving unit, the fixed lens group that does not move in the optical axis direction, and the operating unit. And a lens group including a movable lens group.

  According to the present embodiment, a driving device having a position detection function and advantageous for miniaturization design and a lens device including the driving device are provided.

It is sectional drawing which shows the structure of the interchangeable lens of embodiment of this invention. It is sectional drawing which extracts and shows a part of structure of the interchangeable lens containing the focus drive part which performs focusing of the zoom lens of embodiment of this invention. It is a perspective view which extracts and shows the structure of the detection mechanism for detecting the moving amount | distance and position of a focus lens group of embodiment of this invention. It is a block diagram which shows the circuit structure of the interchangeable lens of embodiment of this invention. It is a figure explaining the relationship between the rotation range (movable range of a focus lens group) of a focus gear cylinder of an embodiment of the present invention, and a detection mechanism. It is a graph which shows the relationship between the amplitude of the analog output waveform of the GMR sensor of embodiment of this invention, and the gap amount of a GMR sensor and a magnetic code | cord board. It is a figure which shows the analog output waveform of the GMR sensor of embodiment of this invention. It is a figure which shows the digital output waveform processed with the comparator of embodiment of this invention. It is a figure which shows the digital output waveform processed with the comparator of embodiment of this invention. It is a figure which shows the position calculation flow which control IC performs in embodiment of this invention. It is a figure which shows typically the relationship between a magnetic code board, the sensor part, and a rib in embodiment of this invention.

  Hereinafter, a driving device according to an embodiment of the present invention will be described with reference to the drawings. In the following, an interchangeable lens for a digital single-lens reflex camera will be described as an embodiment of the drive device.

  FIG. 1 is a cross-sectional view showing a configuration of an interchangeable lens 1 of the present embodiment. As shown in FIG. 1, the interchangeable lens 1 includes a zoom lens including first to sixth group lenses L1 to L6, and is configured to be detachable from a camera body (not shown). The focal length of the zoom lens is changed by changing the relative positional relationship between the first to sixth lens units L1 to L6 in the optical axis AX direction (thrust direction). The second group lens L2 is a focus lens group. As the second lens group L2 moves in the direction of the optical axis AX, the in-focus position of the zoom lens changes.

  The first group lens L1 is held by the first group holding frame 102. The first group holding frame 102 is held by the moving cylinder 104. The moving cylinder 104 is fixed to the rectilinear cylinder 106. A rectilinear cam follower is formed in the rectilinear cylinder 106. The rectilinear cam follower is engaged with a rectilinear groove formed in the guide tube 108 in the direction of the optical axis AX and a cam groove formed in the cam ring 110. When the cam ring 110 rotates in conjunction with the rotation operation of the zoom ring 112, the rectilinear cylinder 106 is guided (moved) in the optical axis AX direction by the rectilinear groove of the guide cylinder 108. When the rectilinear cylinder 106 is moved in the direction of the optical axis AX, the first group lens L1 held by the first group holding frame 102 becomes WIDE in accordance with the amount of movement of the rectilinear cylinder 106 (rotation operation amount of the zoom ring 112). It moves in the optical axis AX direction between the end and the TELE end. As a result, the focal length of the zoom lens composed of the first to sixth group lenses L1 to L6 changes.

  FIG. 2 is a cross-sectional view showing a partial configuration of the interchangeable lens 1 including a focus drive unit that performs focusing of the zoom lens. As shown in FIG. 2, the interchangeable lens 1 is provided with an inner cylinder 114. The interchangeable lens 1 is supported by the camera body by attaching the inner cylinder 114 to the mount cylinder 2 provided in the camera body. A rectilinear cylinder 106, an outer cylinder 116, and a focus receiving cylinder 118 are attached to the inner cylinder 114.

  A focus sheet metal 120 is attached to the outer cylinder 116. A geared motor 122 is attached to the focus sheet metal 120. The output gear 122 a of the geared motor 122 is meshed with the gear portion of the focus gear cylinder 124.

  The focus gear cylinder 124 is rotatably held by a focus receiving cylinder 118 via a sliding member 126. A focus joint cylinder 128 and a first focus lever 130 are attached to the focus gear cylinder 124. When the focus gear cylinder 124 rotates with respect to the focus receiving cylinder 118, the focus joint cylinder 128 and the first focus lever 130 also rotate together.

  A guide hole is formed at the tip of the first focus lever 130. The tip of the second focus lever 132 is inserted into the guide hole of the first focus lever 130 so as to be movable in the thrust direction with respect to the first focus lever 130. The base end of the second focus lever 132 is attached to the focus cam cylinder 134.

  The second group lens L2 is held by the second group holding frame 136. Three roller members are installed on the outer peripheral surface of the second group holding frame 136 at equal pitches in the circumferential direction and screwed. The roller member is engaged with a straight advance groove formed in the focus straight advance cylinder 138 in the optical axis AX direction and a cam groove formed in the focus cam cylinder 134. The focus cam cylinder 134 is held so as to be rotatable with respect to the focus rectilinear cylinder 138.

  When the circuit unit 140 receives AF (Auto Focus) control information from a CPU (Central Processing Unit) on the camera body side, the circuit unit 140 drives the geared motor 122 based on the received AF control information to rotate the output gear 122a. The rotation operation of the output gear 122a is transmitted to the focus gear cylinder 124, and the focus joint cylinder 128 and the first focus lever 130 attached to the focus gear cylinder 124 are rotated integrally with the focus gear cylinder 124. The rotation operation of the first focus lever 130 is transmitted to the second focus lever 132, and the focus cam cylinder 134 attached to the base end of the second focus lever 132 is rotated integrally with the second focus lever 132. In the second group holding frame 136, the roller member formed on the outer peripheral surface moves in the cam groove of the focus cam cylinder 134 as the focus cam cylinder 134 rotates. However, the movement of the roller member (second group holding frame 136) is restricted in the optical axis AX direction by the rectilinear groove of the focus rectilinear cylinder 138. Therefore, the second group lens L2 held by the second group holding frame 136 moves in the optical axis AX direction according to the rotation of the focus cam cylinder 134 (drive of the geared motor 122). As the second group lens L2 moves in the optical axis AX direction with respect to the other lenses, the focus position of the zoom lens changes.

  A detection mechanism for detecting the amount and position of movement of the second group lens L2 in the optical axis AX direction is provided around the focus gear cylinder 124 and its periphery. FIG. 3A and FIG. 3B are perspective views showing an extracted configuration of the detection mechanism. As shown in FIG. 3A, a band-like pasting area 124 a is formed on the outer peripheral surface of the focus gear cylinder 124 along the circumferential direction of the focus gear cylinder 124. A magnetic code plate 142 magnetized at a predetermined pitch is affixed to the affixing region 124a. The base end of the sheet metal part 144 is attached to the outer cylinder 116 (not shown in FIG. 3A).

  A pair of GMR (Giant Magneto Resistance) sensors 146 </ b> A and 146 </ b> B are provided at the front end of the sheet metal part 144. The GMR sensors 146A and 146B change in resistance when the relative position to the magnetic code plate 142 changes, and output the changed resistance as a minute potential difference by the bridge circuit. It should be noted that the magnetization pitch of the magnetic code plate 142 is preferably less than the resolution of focus drive in order to achieve the allowable circle of confusion required in the specifications. Hereinafter, for the convenience of explanation, the front end of the sheet metal part 144 provided with the GMR sensors 146A and 146B is referred to as a “sensor part 144s”. The sensor portion 144s is disposed at a position facing the magnetic code plate 142, and is abutted against the magnetic code plate 142 by a sheet metal portion 144 formed in a plate spring shape.

  A rib 124r is erected on the outer peripheral surface of the focus gear cylinder 124. The rib 124r is formed at a position adjacent to each long side of the pasting region 124a at each end of the pasting region 124a, and has a shape that is long in the circumferential direction along the long side of the pasting region 124a. The rib 124r has a rib main body portion 124ra and a rib inclined portion 124rb. The rib main body portion 124ra has a certain height from the outer peripheral surface (the pasting region 124a) of the focus gear cylinder 124, and the upper surface is an arc surface concentric with the pasting region 124a. The rib inclined portion 124rb has a slope shape that connects the arc surface of the rib main body portion 124ra and the pasting region 124a.

  When the focus gear cylinder 124 rotates relative to the outer cylinder 116 in accordance with the rotation operation of the output gear 122a, the sensor unit 144s moves on the magnetic code plate 142 along the circumferential direction of the focus gear cylinder 124. At this time, as shown in FIG. 3A, the sensor unit 144s maintains the state of being applied to the magnetic code plate 142, and therefore the distance from the magnetic code plate 142 does not change. Therefore, the strength of the magnetic field detected by the GMR sensors 146A and 146B does not change substantially, and the amplitude of the output waveform does not change.

  However, when the focus gear cylinder 124 is rotated toward the end point of the rotation range (the second group lens L2 is moved toward the movable end), as shown in FIG. Ride on the upper surface (slope) of the rib inclined portion 124rb near the end point, gradually move away from the magnetic code plate 142 in the radial direction (direction orthogonal to the optical axis AX), and then reach the arc surface of the rib main body portion 124ra. Move on the arc surface. Since the sensor portion 144s is applied to the arc surface by the sheet metal portion 144 formed in a plate spring shape, the radial distance from the magnetic code plate 142 is kept constant. The amplitude of the output waveform of the GMR sensors 146A and 146B decreases as the distance from the magnetic code plate 142 increases as the sensor portion 144s rides on the inclined surface of the rib inclined portion 124rb. Further, the amplitude of the output waveform of the GMR sensors 146A and 146B does not substantially change because the distance from the magnetic code plate 142 is constant as long as the sensor portion 144s is positioned on the arc surface.

  FIG. 4 is a block diagram mainly showing a circuit configuration of the interchangeable lens 1. In the block configuration shown in FIG. 4, the interchangeable lens 1 includes a code plate 148 (invisible in FIG. 3) in addition to the GMR sensors 146 </ b> A and 146 </ b> B and the geared motor 122 as a fixed member. The interchangeable lens 1 includes a detection brush 150 (invisible in FIG. 3) in addition to the magnetic code plate 142 as a movable member. The circuit unit 140 includes amplifiers 140Aa and 140Ba, comparators 140Ac1, 140Ac2, and 140Bc1, a motor driver IC (Integrated Circuit) 140d, and a control IC 140IC.

  The analog output waveforms (sine waves) of the GMR sensors 146A and 146B are amplified by the amplifiers 140Aa and 140Ba, respectively. The analog output waveform amplified by the amplifier 140Aa is input to the comparators 140Ac1 and 140Ac2, and the analog output waveform amplified by the amplifier 140Ba is input to the comparator 140Bc1. The analog output waveform input to each comparator is converted into a High / Low digital output waveform (rectangular wave) by each comparator and input to the control IC 140IC. Based on the digital output waveform input from each comparator, the control IC 140IC rotates the focus gear cylinder 124 (the amount of movement of the second group lens L2) and the position within the rotation range of the focus gear cylinder 124 (the second group lens L2). (Position within the movable range).

  Here, the code plate 148 is a flexible printed circuit board from which the contact pattern is exposed, and is attached to the outer peripheral surface of the focus gear cylinder 124. The code plate 148 has three patterns (two contact patterns and one GND) for detecting the rotation range of the focus gear cylinder 124 (the movable range of the second group lens L2) separately in four sections. ) Is formed. The detection brush 150 is attached to the focus receiving cylinder 118. The detection brush 150 is applied to the code plate 148 and slides on the code plate 148 when the focus gear cylinder 124 rotates. In accordance with the rotation of the focus gear cylinder 124, the combination of contact patterns that short-circuit with the detection brush 150 changes. The control IC 140IC calculates a position within the rotation range of the focus gear cylinder 124 (a position within the movable range of the second group lens L2) based on the combination of contact patterns detected by the detection brush 150.

  The control IC 140IC controls the motor driver IC 140d based on the AF control information received from the CPU on the camera body side, the calculation result based on the digital output waveform input from each comparator, and the calculation result based on the detection signal of the detection brush 150. Then, the zoom lens is focused by driving the geared motor 122.

  FIG. 5 is a diagram for explaining the relationship between the rotation range of the focus gear cylinder 124 (the movable range of the second group lens L2) and the detection mechanism. FIG. 5A shows the movable range of the focus gear cylinder 124 (second group lens L2). As shown in FIG. 5A, the focus gear cylinder 124 (second group lens L2) moves to the infinite movable end when the geared motor 122 is driven in the forward rotation direction, and the geared motor 122 rotates in the reverse direction. When driven in the direction, it moves to the movable end on the closest side. FIG. 5B shows the magnetic code plate 142 developed linearly in accordance with the rotation range of the focus gear cylinder 124 (the movable range of the second group lens L2). In FIG. 5B, the “magnetic code center range” indicates a range in which the magnetic code plate 142 and the sensor unit 144s are in contact with each other. The “magnetic cord end point range” in the vicinity of each movable end indicates a range in which the magnetic code plate 142 and the sensor portion 144s are separated from each other by the rib 124r (the sensor portion 144s is located on the arc surface of the rib main body portion 124ra). The range in which the sensor portion 144s is located on the slope of the rib inclined portion 124rb is very small and can be substantially ignored without consideration, and is not shown in FIG. 5B. FIG. 5C shows each section of the code plate 148 linearly developed in accordance with the rotation range of the focus gear cylinder 124 (the movable range of the second group lens L2). As shown in FIG. 5C, the code plate 148 follows the combinations of signal patterns detected by the detection brush 150, “closest end point range”, “first central range”, “second central range”. , “Infinite side end point range”.

  FIG. 6 is a graph showing the relationship between the amplitude of the analog output waveforms of the GMR sensors 146A and 146B and the gap amount between the GMR sensors 146A and 146B and the magnetic code plate 142 (no unit for normalization). In FIG. 6, the vertical axis indicates the amplitude, and the horizontal axis indicates the gap amount. From the graph of FIG. 6, it can be seen that the larger the gap amount, the smaller the amplitude.

The interchangeable lens 1 of the present embodiment is designed to satisfy the following conditions in order to prevent erroneous detection of the movement amount and position of the sensor unit 144s (whether it is located in the magnetic code center range or the magnetic code end point range). .
A1 _min > A2 _max + C
A2 _min > C
Here, the symbol A1 _min is a value indicating the minimum amplitude that the analog output waveforms of the GMR sensors 146A and 146B can take when the sensor unit 144s is located in the magnetic code center range of the magnetic code plate 142, and as an error factor, Consideration is given to differences in individual parts of the GMR sensors 146A and 146B and the magnetic code plate 142, environmental changes due to temperature and humidity characteristics, and the like. The symbols A2 _max and A2 _min are values indicating the maximum amplitude and the minimum amplitude that the analog output waveforms of the GMR sensors 146A and 146B can take when the sensor unit 144s is located in the magnetic code end point range of the magnetic code plate 142, respectively. There are error factors such as differences in individual parts of the GMR sensors 146A and 146B and the magnetic code plate 142 (including the thickness of the magnetic code plate 142), environmental changes due to temperature and humidity characteristics, and ribs 124r formed on the focus gear cylinder 124. The error of the height dimension is taken into consideration. Symbol C is a value obtained by converting a parameter of an error amount such as variation in reference voltage (threshold value) and hysteresis of each comparator in accordance with the minimum amplitude A1 _min or the like.

  FIG. 7 is a diagram showing analog output waveforms (sine waves) of the GMR sensors 146A and 146B (no unit for normalization). In FIG. 7, the vertical axis represents the amplitude of the output waveform, and the horizontal axis represents the amount of movement of the sensor 144 s with respect to the magnetic code plate 142. In FIG. 7, the direction from the left to the right is the forward direction, and the direction from the right to the left is the reverse direction. Reference sign V2 indicates a center voltage of a sine wave. The center voltage V2 is also a reference voltage for the comparators 140Ac1 and 140Bc1. Symbols V1 and V3 indicate reference voltages of the comparator 140Ac2, and when the center voltage V2 is set to zero, for example, the values are the same level with the symbols inverted.

  The GMR sensors 146 </ b> A and 146 </ b> B are arranged so as to be shifted by 1/4 pitch with respect to the magnetization pitch of the magnetic code plate 142. Therefore, each of the GMR sensors 146A and 146B outputs two types of sine waves of A phase (solid line in FIG. 7) and B phase (broken line in FIG. 7) whose phases are orthogonal to each other. When the sensor 144s is positioned in the “magnetic code center range”, there is substantially no gap between the GMR sensors 146A and 146B and the magnetic code plate 142, so that the amplitude of the output waveform is large as shown in FIG. . Specifically, the amplitude of the output waveform is larger than the reference voltages V1 and V3 of the comparator 140Ac2. When the position of the sensor 144s is switched from the “magnetic code center range” to the “magnetic code end point range”, the amplitude of the output waveform decreases as the gap amount between the GMR sensors 146A and 146B and the magnetic code plate 142 increases. When the movement to the “magnetic code end point range” is completed, the amplitude of the output waveform becomes smaller than the reference voltages V1 and V3 of the comparator 140Ac2, as shown in FIG.

  FIG. 8 is a diagram showing digital output waveforms processed by the comparators of the comparators 140Ac1 and 140Bc1 (no unit for normalization). In FIG. 8, the vertical axis represents the amplitude of the digital output waveform, and the horizontal axis represents the amount of movement of the sensor 144 s with respect to the magnetic code plate 142. In FIG. 8, the direction from the left to the right is the forward direction, and the direction from the right to the left is the reverse direction. The solid line shows the digital output waveform (A phase) of the comparator 140Ac1, and the broken line shows the digital output waveform (B phase) of the comparator 140Bc1.

  The comparators 140Ac1 and 140Bc1 convert the A-phase and B-phase analog output waveforms shown in FIG. 7 into high / low digital output waveforms using the center voltage V2 as a reference voltage as shown in FIG. To do. Since the center voltage V2 of the sine wave is the reference voltage, the shape of the rectangular wave is always constant regardless of whether the position of the sensor unit 144s is in the magnetic code center range or the magnetic code end point range.

  The control IC 140IC obtains the amount of movement of the sensor unit 144s relative to the magnetic code plate 142 by counting the rise and fall of the digital output waveform of the comparator 140Ac1 and / or the comparator 140Bc1.

  FIG. 9 is a diagram showing the digital output waveform of the comparator 140Ac2 superimposed on the output waveform diagram of FIG. In FIG. 9, the alternate long and short dash line indicates the digital output waveform (A phase) of the comparator 140Ac2. In FIG. 9, the scale is changed from that in FIG. 8 for convenience of explanation.

  The comparator 140Ac2 outputs “High” when the input voltage V is higher than the reference voltage V1 or lower than the reference voltage V3, and outputs “Low” otherwise. Specifically, the analog output waveform of the GMR sensor 146A changes across the reference voltages V1 and V3 periodically as shown in FIG. 7 while the sensor unit 144s is located in the central range of the magnetic code. For this reason, the comparator 140Ac2 converts the analog output waveform into a High / Low digital output waveform and outputs it while the sensor unit 144s is located in the magnetic code center range. At this time, the digital output waveform (A phase) of the comparator 140Ac2 is always “High” when the digital output waveform (B phase) of the comparator 140Bc1 rises and falls as shown in FIG. On the other hand, the analog output waveform (A phase) of the GMR sensor 146A falls between the reference voltage V1 and the reference voltage V3 as shown in FIG. 7 while the sensor unit 144s is located in the magnetic cord end point range. Therefore, the comparator 140Ac2 converts the analog output waveform into a digital output waveform of a certain level (Low) and outputs it while the sensor unit 144s is located in the magnetic code end point range.

  Thus, in this embodiment, by adopting a configuration in which the physical distance between the magnetic code plate 142 and the sensor unit 144s is changed according to each range along the outer peripheral surface shape of the focus gear cylinder 124, the magnetic code The position of the sensor unit 144s with respect to the plate 142 can be detected.

  Table 1 shows the relationship between the digital output waveform of each comparator and the calculation result by the control IC 140IC. The control IC 140IC detects High / Low of the digital output waveforms (A phase) of the comparators 140Ac1 and 140Ac2 using the rising and falling edges of the digital output waveform (B phase) of the comparator 140Bc1 as triggers, and a sensor unit for the magnetic code plate 142 The moving direction and position of 144s are calculated.

(Table 1)

  As shown in Table 1, if the digital output waveform (A phase) of the comparator 140Ac1 is “High” when the digital output waveform (B phase) of the comparator 140Bc1 rises, the control IC 140IC causes the sensor unit 144s to detect the magnetic code. If it is determined that the plate 142 is moving in the reverse direction (movable end on the near side) and the digital output waveform (A phase) of the comparator 140Ac1 is “Low”, the sensor unit 144s is connected to the magnetic code plate 142. On the other hand, it determines with moving to the normal rotation direction (infinite side movable end).

  Further, if the digital output waveform (A phase) of the comparator 140Ac1 is “High” when the digital output waveform (B phase) of the comparator 140Bc1 falls, the control IC 140IC causes the sensor unit 144s to move to the magnetic code plate 142. If the digital output waveform (A phase) of the comparator 140Ac1 is “Low” when it is determined that it is moving in the forward rotation direction (infinite movable end), the sensor unit 144s is in the reverse rotation direction with respect to the magnetic code plate 142. It determines with moving to (movable end on the near side).

  The control IC 140IC further detects that the digital output waveform (A phase) of the comparator 140Ac2 is “High” when the digital output waveform (B phase) of the comparator 140Bc1 falls or falls. If the digital output waveform (A phase) of the comparator 140Ac2 is “Low”, it is determined that the sensor 144s is located in the magnetic code end point range.

  Here, instead of the magnetic code plate 142 of the present embodiment, a configuration in which a code plate (flexible printed circuit board) on which a position detection pattern is formed is attached to the focus gear cylinder 124 will be considered. In this configuration, a code plate sticking error to the focus gear cylinder 124, a pattern print misalignment, or the like (for example, about 0.1 mm to 0.5 mm) occurs. This type of error is much larger than the resolution required for position detection (for example, several μm to several tens of μm). Therefore, in order to perform accurate position detection, correction processing is required for the detection signal detected from the code plate.

  On the other hand, in this embodiment, the position of the sensor portion 144s with respect to the magnetic code plate 142 (magnetic code center range or magnetic code end point range) uses the outer peripheral surface shape (including the rib 124r) of the focus gear cylinder 124 itself. Is detected. For this reason, in the present embodiment, it is not necessary to consider a code plate sticking error or a pattern print misalignment in detecting the position on the magnetic code plate 142, and accurate position detection is easily achieved.

  The control IC 140IC detects whether the sensor 144s is located in the magnetic code center range or the magnetic code end point range by constantly monitoring the digital output waveform of the comparator 140Ac2 even when the comparator 140Bc1 is not provided. can do. That is, the control IC 140IC can calculate the moving direction and position of the sensor unit 144s with respect to the magnetic code plate 142 even if the interchangeable lens 1 has only one GMR sensor (GMR sensor 146A).

  Thus, in this embodiment, the position of the sensor unit 144s can be detected by the movement amount detection mechanism using the magnetic code plate 142 and the GMR sensors 146A and 146B. By adding the position detection function to the movement amount detection mechanism, the number of contact patterns of the code plate 148 constituting the position detection mechanism can be reduced, which is advantageous for the miniaturization design of the interchangeable lens 1.

  The control IC 140IC calculates the position of the sensor unit 144s relative to the magnetic code plate 142 in parallel with the calculation of the movement amount of the sensor unit 144s relative to the magnetic code plate 142. FIG. 10 shows a position calculation flow by the control IC 140IC. The position calculation flow shown in FIG. 10 is executed when focusing is performed based on AF control information received from the CPU on the camera body side.

  As shown in FIG. 10, the control IC 140IC determines whether or not the sensor unit 144s is located in the magnetic code end point range based on the digital output waveform input from each comparator (S11). When the control IC 140IC determines that the sensor unit 144s is located in the magnetic cord end point range (S11: YES), the rotational position (second group) of the focus gear cylinder 124 based on the combination of signal patterns detected by the detection brush 150. The position of the lens L2 is determined (S12). When it is determined that the control IC 140IC is located in the closest end point range in processing step S12 (S12: close side), the drive of the geared motor 122 in the reverse direction is limited in order to avoid collision of each movable member with the movable end ( S13). When it is determined that the control IC 140IC is located in the endless side end point range in the processing step S12 (S12: infinite side), the driving of the geared motor 122 in the forward rotation direction is limited in order to avoid collision of each movable member with the movable end. (S14).

  The magnetic code end point range of the magnetic code plate 142 is a region that is difficult to use for focusing control because the movement of each movable member is limited. In order to secure a wide area used for focusing control, the boundary between the magnetic code center range and the magnetic code end point range is preferably closer to the movable end. In the present embodiment, since the boundary and the movable end are defined by the shape of the focus gear cylinder 124, the boundary can be disposed near the movable end with high accuracy.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes an embodiment that is exemplarily specified in the specification or a combination of obvious embodiments and the like as appropriate.

  FIG. 11A is a diagram schematically showing a relationship among the magnetic code plate 142, the sensor portion 144s, and the rib 124r in the present embodiment. FIG. 11B is a diagram schematically showing the relationship among the magnetic code plate 142, the sensor portion 144s, and the rib 124r in another embodiment. In each of FIGS. 11A and 11B, the outer peripheral surface shape of the focus gear cylinder 124 and the magnetic code plate 142 are shown in a straight line for convenience.

  In the present embodiment, as shown in FIG. 11A, the rib 124r is formed only in the vicinity of both movable ends (magnetic cord end point range). On the other hand, in another embodiment, as shown in FIG. 11B, the rib 124r is formed near the movable end on the near side (the magnetic cord end point range on the left side in FIG. 11B). However, it is formed over the entire magnetic cord central range, and has a height higher than the magnetic cord central range in the vicinity of the infinite movable end (the right magnetic cord end point range in FIG. 11B). It is formed with. By adopting such a rib shape, the magnetic cord 142 and the sensor portion 144s have different distances in each of the magnetic cord end point range (closest side), the magnetic code center range, and the magnetic code end point range (infinite side). Placed in. Therefore, even if there is no signal pattern detected by the detection brush 150, the control IC 140IC can determine whether the sensor unit 144s is located in the magnetic cord end point range on the near side or the infinite side. In yet another embodiment, by forming the ribs 124r in more stages, the control IC 140IC can finely position the sensor portion 144s with respect to the magnetic code plate 142 even if there is no signal pattern detected by the detection brush 150. It can be calculated.

  In this embodiment, the rotation amount of the focus gear cylinder 124 (the amount of movement of the second group lens L2) is detected using the magnetic code plate 142 and the GMR sensors 146A and 146B, but in another embodiment, Focusing on the manufacturing cost, the rotation amount of the focus gear cylinder 124 (of the second group lens L2) using a photo reflector and a reflection sheet (a pattern in which a reflection portion and a non-reflection portion are periodically arranged) is used. (Movement amount) may be detected.

  In this case, for example, as the photo reflector and the reflection sheet are separated from each other by the rib 124r, the intensity of the pattern detected by the photo reflector (the intensity of light reflected by the reflecting portion) decreases. Similarly to the example of FIG. 9, the comparator 140Ac2 outputs “High” when the photoreflector is applied to the reflection sheet at the rise and fall of the digital output waveform (B phase) of the comparator 140Bc1. When the reflector is applied to the arc surface of the rib main body 124ra, “Low” is output.

DESCRIPTION OF SYMBOLS 1 Interchangeable lens 2 Mount cylinder 102 1st group holding frame 104 Moving cylinder 106 Straight advance cylinder 108 Guide cylinder 110 Cam ring 112 Zoom ring 114 Inner cylinder 116 Outer cylinder 118 Focus receiving cylinder 120 Focus sheet metal 122 Geared motor 122g Output gear 124 Focus gear cylinder 124a Affixing region 124r Rib 124ra Rib body portion 124rb Rib inclined portion 126 Slide member 128 Focus joint tube 130 First focus lever 132 Second focus lever 134 Focus cam tube 136 Second holding frame 138 Focus rectilinear tube 140 Circuit portions 140Aa, 140Ba Amplifier 140Ac1, 140Ac2, 140Bc1 Comparator 140d Motor driver IC
140IC Control IC
142 Magnetic code plate 144 Sheet metal portion 144s Sensor portion 146A, 146B GMR sensor 148 Code plate 150 Detection brushes L1 to L6 First to sixth lens groups

Claims (13)

Detected means in which a predetermined pattern is periodically formed;
Detecting means for detecting the pattern with an intensity corresponding to a distance from the detected means;
Operating means capable of relatively operating the detected means and the detecting means;
A distance defining means for defining a distance between the detected means and the detecting means according to a position of the detecting means with respect to the detected means;
Based on the number of patterns detected by the detecting means, the amount of movement of the detecting means relative to the detected means is calculated, and the position of the detecting means relative to the detected means is calculated according to the strength of the detected pattern. Computing means for
Comprising
Drive device. First holding means for holding the detected means;
Second holding means for holding the detecting means;
With
The operating means includes
By moving the first holding means and the second holding means relative to each other, the detection means is moved relative to the detected means held on the first holding means,
The distance defining means is
An urging means for urging the detecting means toward the detected means held on the first holding means;
A protrusion including at least one step formed on the first holding unit along a moving direction of the detection unit with respect to the detection unit, and biased toward the detection unit by the biasing unit; By defining the distance between the detected means and the detecting means at an interval according to the height of the step by receiving the detected means;
including,
The drive device according to claim 1. The protrusion is
Formed on the first holding means along the moving direction in a part of the moving range of the detecting means relative to the detected means;
The detection means includes
In the area where the protrusion is not formed in the movement range, the biasing means biases the detection target without passing through the protrusion.
The drive device according to claim 2. The first holding means is
A cylindrical member that holds and holds a predetermined moving object,
The detected means is
A magnetic code plate that is affixed along the circumferential direction on the outer peripheral surface of the cylindrical member and is magnetized at a predetermined pitch,
The detection means includes
A magnetic sensor for detecting a magnetic field change of the magnetic code plate;
The protrusion is
The magnetic code plate, the magnetic sensor, and the magnetic sensor having a rib shape erected along the magnetic code plate on the outer peripheral surface of the cylindrical member and receiving the magnetic sensor biased by the biasing means, Stipulate the distance according to its height,
The drive device according to claim 2 or claim 3. The first holding means is
A cylindrical member that holds and holds a predetermined moving object,
The detected means is
A reflective sheet that is affixed along the circumferential direction on the outer peripheral surface of the cylindrical member, and in which a pattern in which a reflective portion and a non-reflective portion are periodically arranged is formed,
The detection means includes
A photo reflector for detecting a pattern formed on the reflective sheet;
The protrusion is
A rib shape standing along the reflection sheet on the outer peripheral surface of the cylindrical member, and receiving a photo reflector urged by the urging means, thereby providing a distance between the reflection sheet and the photo reflector. Stipulates the interval according to its height,
The drive device according to claim 2 or claim 3. The computing means is
Waveform output means for outputting different waveforms according to the intensity of the pattern detected by the detection means;
Position calculating means for calculating the position of the detection means relative to the detected means based on the waveform output by the waveform output means;
including,
The driving device according to any one of claims 1 to 5. The waveform output means includes
Including a binarization circuit for converting an analog waveform of a pattern detected by the detection means into a binarized waveform;
The drive device according to claim 6. The binarization circuit is
A threshold for the strength of the analog waveform is set so that a different binarized waveform is output for each distance between the detected unit and the detecting unit defined by the distance defining unit,
The position calculating means includes
Calculating the position of the detection means relative to the detected means based on the binarized waveform output from the binarization circuit;
The drive device according to claim 7. The binarization circuit is
A first comparator that always converts the analog waveform into the same binarized waveform regardless of the distance between the detected means and the detection means defined by the distance defining means;
A second comparator for converting the analog waveform into a binary waveform different for each distance;
Including
The computing means is
A moving amount calculating means for calculating a moving amount of the detecting means relative to the detected means based on a first binarized waveform output by the first comparator;
The position calculating means includes
Calculating the position of the detection means relative to the detected means based on the second binarized waveform output by the second comparator;
The drive device according to claim 7 or 8. The binarization circuit is
A third comparator for always converting the analog waveform into the same binarized waveform regardless of the distance between the detected means and the detecting means defined by the distance defining means;
The detection means includes
A pair of detection sensors for detecting the A phase and the B phase whose phases are orthogonal to each other;
The second comparator is
Converting the analog waveform of the A phase into the second binarized waveform;
The third comparator is
Converting the B-phase analog waveform into a third binarized waveform;
The position calculating means includes
The position of the detection means relative to the detected means is specified by High / Low of the second binarized waveform at the time of rising and falling of the third binarized waveform.
The drive device according to claim 9. The position calculating means includes
Determining whether the position of the detection means relative to the detected means is near the end point of the movement range of the detection means;
The operating means includes
When the position of the detection means relative to the detection means is determined to be near the end point of the moving range, the relative operation between the detection means and the detection means is limited;
The drive device according to any one of claims 6 to 10. A detection brush held by the first holding member;
A cord plate which is held by the second holding member and has a predetermined contact pattern;
With
The position calculating means includes
When the position of the detecting means relative to the detected means is determined to be near the end point of the moving range, the detecting means is near one end point or the other end point based on the contact pattern of the code plate detected by the detection brush. To determine if it ’s nearby,
The operating means includes
If the position of the detection means relative to the detected means is determined to be near the one end point, the movement of the detection means to the one end point is limited,
Limiting the movement of the detection means to the other end point when the position of the detection means relative to the detected means is determined to be near the other end point;
The drive device according to claim 11. A driving device according to any one of claims 1 to 12,
A fixed lens group that does not move in the optical axis direction, and a lens group that includes a movable lens group that moves in the optical axis direction in accordance with the relative movement of the detected means and the detecting means by the operating means;
Comprising
Lens device.

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