JP5384320B2 - Lens device position detection device - Google Patents

Description

  The present invention relates to a position detection device for a lens device, and in particular, a lens that detects the absolute position of a movable lens such as a zoom lens group with high accuracy using an absolute type position sensor with low resolution and a relative type position sensor with high resolution. The present invention relates to a position detection apparatus for an apparatus.

  2. Description of the Related Art Conventionally, as a lens device used for a portable ENG (Electronic News Gathering) camera used for TV coverage or the like, an inner focus type lens device and a rear focus type lens device are known (Patent Documents 1 to 3). 3).

  In such a lens apparatus, the absolute position of the movable lens is not detected using an expensive absolute type position sensor with a high resolution, but a relatively inexpensive absolute type position sensor with a low resolution and a high resolution in order to reduce costs. Some of them are performed using a relative position sensor. For example, the absolute position (initial position) of the movable lens is detected by an absolute position sensor at a predetermined time such as when the power is turned on, and then the displacement from the absolute position is detected by a relative position sensor. The current absolute position is obtained with high accuracy from the sum of the displacement. Note that an MR (magnetoresistive) sensor is known as a relative position sensor, and Patent Document 4 discloses a lens device that detects the position of a movable lens using an MR sensor.

Japanese Patent Laid-Open No. 9-211303 JP 2007-148021 A JP 2007-102106 A Japanese Patent Laid-Open No. 11-110045

  When the absolute position of the movable lens is detected using the absolute position sensor and the relative position sensor as described above, the position detection (displacement amount detection) is performed only by the relative position sensor except when the initial position is detected. It has been broken. For this reason, when the relative type position sensor fails, there is a problem that the position cannot be detected and the control using the result of the position detection becomes impossible. For example, when an MR sensor is used as a relative position sensor, a magnetic ring (multi-polar permanent magnet) in which N and S poles are alternately magnetized and moves relative to the MR sensor in conjunction with a movable lens. If the magnetic ring is in a state where it slides on another member, the magnetic ring will be damaged and the MR sensor will not output a signal normally in addition to the circuit failure of the MR sensor itself. There is also a case.

  The present invention has been made in view of such circumstances, and is a case where a relative position sensor fails in a lens apparatus that detects the absolute position of a movable lens using an absolute position sensor and a relative position sensor. However, it is an object of the present invention to provide a position detection device for a lens device in which the absolute position of a movable lens is detected.

In order to achieve the above object, a position detection apparatus for a lens device according to claim 1 includes an optical system including a movable lens, an absolute position sensor that detects an absolute position of the movable lens, and a displacement amount of the movable lens. The relative type position sensor to be detected and the absolute position of the movable lens at a predetermined time are acquired from the absolute type position sensor, and the displacement amount of the movable lens from the absolute position to the current position is acquired from the relative type position sensor. Accordingly, in the position detecting device of the lens apparatus, the calculating means for detecting the current position of the movable lens based on the absolute position and the displacement amount, the calculating means is configured to move the movable lens from a predetermined time to the current time. A value Δx ′ obtained when the displacement amount of the lens is obtained based on the absolute position acquired from the absolute position sensor, and the displacement amount acquired from the relative position sensor. By comparing the values Δx when calculated on the basis, the abnormality detecting means for the relative position sensor detects whether abnormal or not, when it is detected that an abnormality by the abnormality detecting means, the And a detection position repairing means that directly uses the current absolute position acquired from the absolute position sensor as the current position of the movable lens.

  According to the present invention, when an abnormality occurs in the relative position sensor, the current position of the movable lens is detected by the absolute position detected by the absolute position sensor without using the relative position sensor. . Therefore, the problem that the position of the movable lens cannot be detected due to the failure of the relative position sensor is avoided.

  According to a second aspect of the present invention, there is provided a lens device position detecting device according to the first aspect of the invention, further comprising display means for displaying an abnormality when the abnormality detecting means detects the abnormality.

  According to the present invention, when an abnormality occurs in the relative position sensor, the user can recognize this, and can recognize the necessity for repair or the like.

  According to a third aspect of the present invention, there is provided the position detecting device for a lens device according to the first or second aspect, wherein the absolute position sensor is interlocked with a resistor to which a voltage is applied at both ends and the movable lens. A potentiometer that outputs a voltage according to the position of the movable lens from the sliding body. The relative type position sensor moves relative to the multipolar permanent magnet body in conjunction with the movable lens at a position facing the multipolar permanent magnet body in which N poles and S poles are alternately magnetized. The MR sensor outputs a pulse signal having the number of pulses corresponding to the displacement amount of the movable lens. The present invention shows specific modes of an absolute position sensor and a relative position sensor.

According to a fourth aspect of the present invention, in the lens device position detection device according to the first, second, or third aspect of the invention, the abnormality detection means has a predetermined absolute value of a difference between the value Δx and the value Δx ′. When the value is less than α, the relative position sensor is determined to be normal. When the absolute value of the difference between the value Δx and the value Δx ′ is greater than or equal to the predetermined value α, the relative position sensor is abnormal. The mode to judge is shown.

  According to the present invention, in a lens device that detects an absolute position of a movable lens using an absolute position sensor and a relative position sensor, the absolute position of the movable lens can be detected even if the relative position sensor fails. Detection is performed.

The sectional view which looked at the lens device to which the present invention was applied from the side. The block diagram which showed the structure of the structure part which performs the position detection of a zoom lens. 6 is a flowchart showing a processing procedure for detecting the position of a zoom lens in the main MPU.

  Hereinafter, embodiments of a lens apparatus according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view of a rear focus type variable focal length lens device applied to the present invention applied to, for example, a consumer video camera, a television broadcast ENG camera, a surveillance camera, etc., as viewed from the side. Yes, with respect to the upper half from the optical axis O.

  1, the lens barrel body of the lens apparatus 1 mainly includes a front frame 10, a front fixed ring 12, a first main body ring 14, a second main body ring 16, a rear fixed ring 18, a mount mounting frame 20, and a mount ring 22. It is comprised by the substantially cylindrical shape.

  The first main body ring 14 is an innermost component of the lens barrel main body. The front fixed ring 12 is fixed to the front side of the outer periphery of the first main body ring 14 with a screw, and the front of the front fixed ring 12 is in front. The frame 10 is fixed with screws. Further, the second main body ring 16 is fixed to the rear side of the outer periphery of the first main body ring 14 with a screw, the rear fixed ring 18 is located behind the second main body ring 16, the mount mounting frame 20 is located behind the rear fixed ring 18, Mount rings 22 are fixed to the rear of the mount mounting frame 20 with screws.

  A lens hood 24 can be attached to the front frame 10. The lens device 1 is mounted on a camera body with interchangeable lenses via a mount ring 22.

  The optical system in the lens apparatus 1 includes, in order from the object side, a fixed lens (first group lens) 30, a zoom (variation) lens (second group lens) 32, a front master lens (third group lens) 34, a focus. It consists of five groups, a lens (fourth group lens) 36 and a rear master lens (fifth group lens) 38. In addition, an iris diaphragm 40 is provided immediately before the front master lens 34.

  The lens frame 42 to which the zoom lens 32 is attached is fixed to the moving frame 46 by a presser ring 44. A cam cylinder 48 is rotatably held on the inner peripheral portion of the first main body ring 14, and the moving frame 46 is held on the inner peripheral portion of the cam cylinder 48 via a cam pin 46A.

  That is, a rectilinear groove 14A in the direction of the optical axis O is formed on the inner peripheral surface of the first main body ring 14, and a cam groove (cam-shaped hole) 48A is formed in the cam cylinder 48. The cam pin 46 </ b> A fixed to is inserted into the cam groove 48 </ b> A of the cam cylinder 48 and engaged with the rectilinear groove 14 </ b> A of the first main body ring 14. As a result, the moving frame 46 is held so as to be able to advance straight in the direction of the optical axis O in a state where the rotation is restricted, and at the position where the cam pin 46A is engaged with the cam groove 48A.

  Therefore, when the cam cylinder 48 rotates, the intersection position of the cam groove 48A of the cam cylinder 48 and the rectilinear groove 14A of the first main body ring 14 changes to a position corresponding to the cam shape, and the cam pin 46A to the intersection position changes. Due to the movement, the moving frame 46 moves back and forth in the direction of the optical axis O.

  On the other hand, a zoom ring 50 is rotatably disposed on the outer peripheral portion of the second main body ring 16, and a rod-like connecting shaft 52 is attached radially inward of the inner peripheral surface of the zoom ring 50. . The connecting shaft 52 is connected to the cam cylinder 48 through a long hole (not shown) in the circumferential direction formed in the first main body ring 14. As a result, when the zoom ring 50 is rotated, the cam cylinder 48 is rotated in conjunction therewith. When the cam cylinder 48 rotates, the moving frame 46 moves forward and backward as described above, and the zoom lens 32 moves in the direction of the optical axis O in conjunction with the moving frame 46. Accordingly, the zoom magnification is changed by rotating the zoom ring 50.

  The iris diaphragm 40 is mainly configured by a plastic base plate (aperture frame) 54, a chrysanthemum seat (cam plate) 56, and a plurality of diaphragm blades 58 disposed between the diaphragm frame 54 and the cam plate 56. ing. An iris ring 60 is rotatably disposed between the rear fixed ring 18 and the mount mounting frame 20, and a connecting shaft 56 </ b> A extending from the cam plate 56 is connected to the iris ring 60. Thus, the cam plate 56 is rotated by the rotation of the iris ring 60, and the aperture blade 58 is opened and closed.

  The focus lens 36 changes the focal position of the optical system, and includes a holding frame 62 that holds the front master lens 34 and the like, and a lens frame 64 of the rear master lens 38 that is disposed at the rear end of the holding frame 62. Are supported so as to be movable in the direction of the optical axis O by a guide shaft and a detent (not shown) held between them. The holding frame 62 is provided with a pair of voice coil motors (VCM) 66 with a guide shaft interposed therebetween, and the focus lens 36 is electrically driven by the power of the VCM 66.

  A first focus ring 70 and a second focus ring 72 are rotatably arranged on the outer peripheral portion of the front fixed ring 12. The rotation range of the first focus ring 70 is not restricted, and the first focus ring 70 can be rotated endlessly and is slidable in the optical axis direction. Further, the second focus ring 72 is restricted by a stopper shaft 74 so as to be rotatable within a range of about 120 degrees.

  Sawtooth-shaped clutch portions 70A and 72A are formed on the end faces where the first focus ring 70 and the second focus ring 72 face each other. In the state shown in FIG. 1, the clutch portions 70A and 72A are connected (engaged). Then, the first focus ring 70 and the second focus ring 72 rotate integrally. Therefore, in this state, when the first focus ring 70 is manually rotated, it can be rotated only within a range of about 120 degrees.

  On the other hand, when the first focus ring 70 is slid forward so as to get over the click elastic member 76, the clutch portions 70A and 72A are disconnected. Thereby, the first focus ring 70 can be rotated endlessly.

  A drive unit (not shown) that also serves as a grip unit is attached to the side surface of the lens device 1 having the above configuration via screw holes 80 and 82.

  The drive unit includes a drive unit for driving the zoom ring 50 and the iris ring 60, and a control board is disposed inside, and the zoom lens 32 and the like are driven and controlled electrically by a seesaw type zoom switch, and the focus is adjusted. The lens 36 and the iris diaphragm 40 are controlled.

  The first main body ring 14 is provided with a linear potentiometer (zoom linear potentiometer) as an absolute position sensor for detecting the position (absolute position) of the zoom lens 32 in the optical axis direction. The zoom linear potentiometer includes a resistor (resistive element) to which a predetermined voltage is applied at both ends and a sliding body (sliding contact) that moves along the resistor and outputs a voltage corresponding to the position. Although not shown, for example, a resistor is attached to the inner peripheral surface of the first main body ring 14 along the optical axis direction, and the slider is attached to the cam pin 46A and the like so as to contact the resistor. According to this zoom linear potentiometer, when the zoom lens 32 moves in the optical axis direction by the rotation of the cam cylinder 48, a position signal (signal indicating an absolute position) corresponding to the moving position is sent to the lead wire connected to the sliding body. Via the drive unit. It should be noted that the resistor and the sliding body only need to be in a relationship in which one moves relative to the other as the zoom lens 32 moves. The resistor moves as the zoom lens 32 moves, and the sliding body moves. You may make it the structure fixed to a predetermined position.

  The first main body ring 14 is provided with a magnetic sensor (MR (magnetoresistive) sensor) as a relative position sensor for detecting the position (relative position) of the zoom lens 32 in the optical axis direction. Yes. The MR sensor moves along a magnetic ring (multi-pole permanent magnet body) in which N poles and S poles are alternately magnetized, and a pulse having a fixed number of pulses every predetermined movement amount (predetermined rotation angle) due to a change in the magnetic field. A sensor circuit (chip) that outputs a signal is included, and the sensor circuit is configured by, for example, a magnetoresistive effect element (MR element) that is bridge-connected. As shown in FIG. 1, a magnetic ring 84 is bonded to the rear end surface of the cam cylinder 48, and an MR sensor 85 is attached to the first main body ring 14 so as to face the magnetic ring 84. According to this, when the zoom lens 32 moves in the optical axis direction by the rotation of the cam barrel 48, a pulse signal (signal indicating a relative position) having a pulse number corresponding to the movement amount (displacement amount) is read from the MR sensor 85. It is output to the drive unit via a line. Although details will be described later, the output of the zoom linear POT is used when the power is turned on, and thereafter, the output of the MR sensor 85 for detecting the zoom lens position is used. The MR sensor 85 and the magnetic ring 84 only need to be in a relationship in which one moves relative to the other as the zoom lens 32 moves, and the MR sensor 85 moves as the zoom lens 32 moves. The magnetic ring 84 may be configured to be fixed at a predetermined position.

  The holding frame 62 facing the guide shaft of the focus lens 36 is provided with an MR sensor for detecting the focus lens position. This MR sensor has a pulse signal (number of pulses corresponding to the amount of movement of the focus lens 36). A signal indicating a relative position) is output to the drive unit via the lead wire. In addition, a home position sensor (photo interrupter) for detecting the reference position of the focus lens 36 is disposed in the holding frame 62, and the drive unit determines the reference position of the focus lens 36 detected by the home position sensor. The absolute position of the focus lens 36 is detected by counting the output signal of the MR sensor with reference.

  Gears 70B and 72B are formed around the first focus ring 70 and the second focus ring 72, respectively, and these gears 70B and 72B are respectively relative position detection type sensors (incremental) provided on the drive unit side. Encoder), and a detection shaft gear of an absolute position detection type sensor (absolute encoder).

  Accordingly, the drive unit can detect the relative rotation amount of the first focus ring 70 and can detect the absolute rotation position of the second focus ring 72.

  In addition, a photo interrupter 86 is provided at the front end of the front fixed ring 12, while a light shielding plate 70 </ b> C is provided at the front end of the first focus ring 70. The photo interrupter 86 outputs a detection signal indicating the presence or absence of the light shielding plate 70C to the drive unit. Accordingly, the driving unit can detect whether or not the first focus ring 70 is connected to the second focus ring 72 based on the detection signal from the photo interrupter 86.

  The position detection of the zoom lens 32 of the lens apparatus 1 will be described in detail below. When a seesaw-type zoom switch provided in the drive unit is operated, a rotational driving force is transmitted from an electric motor in the drive unit to a gear 50A formed around the zoom ring 50, thereby rotating the zoom ring 50. It can be made to. The zoom ring 50 can also be manually rotated.

  When the zoom ring 50 rotates in this way, the cam cylinder 48 connected via the connecting shaft 52 rotates, and when the cam cylinder 48 rotates, the rectilinear groove formed in the first main body ring 14. The moving frame 46 moves forward and backward in the direction of the optical axis O via the cam pin 46A engaged with the cam groove 48A of the cam barrel 48 and 14A. As a result, the zoom lens 32 moves in the direction of the optical axis O, and the zoom magnification is changed.

  In the configuration of the optical system of the lens apparatus 1 according to the present embodiment, the focal plane (focus position) changes when the position of the zoom lens 32 changes. Therefore, the drive unit changes the position of the zoom lens 32 to prevent this. In this case, the focus lens 36 is also moved by a correction amount corresponding to the positions of the zoom lens 32 and the focus lens 36, and therefore the position (zoom position) of the zoom lens 32 is detected. Further, the position of the zoom lens 32 (zoom position) is also detected when the zoom lens 32 is moved to a designated position by an external signal or when the position information of the zoom lens is output to an external device.

  FIG. 2 is a block diagram illustrating a configuration of a configuration unit that detects the position of the zoom lens 32. In the figure, a main MPU (Micro Processing Unit) 100, a sub MPU 102, and an A / D converter 104 are mounted on a drive unit, and a zoom linear potentiometer 106 and an MR sensor 85 are installed on a lens barrel as described above. ing.

  As shown in the figure, the output of the zoom linear potentiometer 106, which is an absolute value position sensor, is input to the A / D converter 104 of the driving unit via a lead wire, and the 14-bit analog signal is output from the analog signal by the A / D converter 104. It is converted into a digital signal having a value (0 to 16383) and taken into the main MPU 100. As a result, the absolute position of the zoom lens 32 is detected by the main MPU 100.

  On the other hand, the output of the MR sensor 85, which is a relative position sensor, is input to the sub-MPU 102 of the driving unit via a lead wire, and the number of pulses of the signal input by the sub-MPU 102 is counted. Although details are omitted, the displacement direction of the zoom lens 32 can also be detected from the output signal of the MR sensor 85, and the sub MPU 102 moves the zoom lens 32 in a predetermined displacement direction (positive direction). In addition, the number of pulses of the pulse signal input during the movement is added to the count value, and the number of pulses of the pulse signal input during movement in the opposite direction (negative direction) is subtracted from the count. The count value counted by the sub MPU 102 is taken into the main MPU 100. Thereby, the main MPU 100 detects the amount of displacement of the zoom lens 32 from when the count value of the sub MPU 102 is reset to zero.

  The main MPU 100 captures the position (initial position) of the zoom lens 32 from the zoom linear potentiometer 106 via the A / D converter 104 (zoom, for example) when the power is turned on to start detection of the zoom position. (Referred to as the value of the linear potentiometer 106). At this time, the count value in the sub MPU 102 is set to zero. Thereafter, the count value of the sub MPU 102 (also referred to as the value of the MR sensor 85) based on the output signal of the MR sensor 85 is appropriately acquired, and the current position (count value is acquired from the initial position of the zoom lens 32 based on the acquired count value. The amount of displacement until the position) Then, the current position is obtained by adding the displacement amount to the value of the initial position. Here, the resolution of the MR sensor is more than 10 times higher than the resolution of the zoom linear potentiometer 106, and position detection other than the initial position is performed using the MR sensor 85, so that highly accurate position detection can be performed. To be done.

  Each time the current position is obtained (each time a count value is acquired from the sub MPU 102), the current position may be set as an initial position, and the count value of the sub MPU 102 may be reset to zero. Further, the value of the zoom linear potentiometer 106 captured at any time other than when the power is turned on may be set as the initial position value, and the count value may be reset to 0 from the sub MPU 102.

  Further, the main MPU 100 detects the position of the zoom lens 32 erroneously when the MR sensor 85 is damaged. Therefore, in order to detect this, the main MPU 100 detects whether the MR sensor 85 is abnormal, The repair process is performed when it is detected.

That is, the main MPU 100 compares the displacement amount of the zoom lens 32 from the predetermined time to the current time with the value obtained from the value of the MR sensor 85 and the value obtained from the value of the zoom linear potentiometer 106, and there is a large difference. If it has occurred, it is determined that an abnormality has occurred in the MR sensor 85. Specifically, the value of the MR sensor 85 (the count value of the sub MPU 102) and the value of the zoom linear potentiometer 106 are captured, and the newly captured current value of the MR sensor 85 and the previous (or a predetermined number of times before, below) Similarly, the amount of displacement Δx of the zoom lens 32 indicated by the difference from the previous value of the MR sensor 85 taken in, the value of the current zoom linear potentiometer 106 newly taken in, and the value of the previous zoom linear potentiometer 106 taken in the previous time The displacement amount Δx ′ of the zoom lens 32 indicated by the difference is compared. When the condition that the difference between the displacement amount Δx and the displacement amount Δx ′ (absolute value of the difference) is less than the predetermined value α, that is, the displacement amount Δx is expressed by the following equation (1):
(Δx′−α) <Δx <(Δx ′ + α) (1)
When the condition is satisfied, it is determined that the MR sensor 85 is normal, and the current position of the zoom lens 32 is obtained using the value of the MR sensor 85.

  On the other hand, when the conditional expression (1) is not satisfied, it is determined that the MR sensor 85 is abnormal. At this time, the main MPU 100 employs the current value of the zoom linear potentiometer 106 as the value of the current position.

  FIG. 3 is a flowchart showing a processing procedure for detecting the position of the zoom lens 32 in the main MPU 100. When the power is turned on, the main MPU 100 takes in the value of the zoom linear potentiometer 106 via the A / D converter 104, and sets it as the initial position value of the zoom lens 32 based on the value (step S10). Also, the count value of the sub MPU 102 is set to zero. And the loop processing of the following step S12-step S20 is repeatedly performed. The zoom lens 32 is driven by rotating the zoom ring 50 by an electric motor in the drive unit or manually while the following loop processing of Step S12 to Step S20 is executed. When the zoom ring 50 is rotated by the electric motor, the main MPU 100 also performs the motor control, and although not shown in the flowchart of FIG. 3, the process for the motor control is also performed in steps S12 to S20. Repeatedly executed with loop processing.

  In the loop processing from step S12 to step S20, the main MPU 100 takes in the value of the zoom linear potentiometer 106 via the A / D converter 104 (step S12), and also takes the value of the MR sensor 85 (count value of the sub MPU 102). Capture from the sub MPU 102 (step S14).

  Subsequently, the displacement of the zoom lens 32 indicated by the difference between the current value of the MR sensor 85 newly acquired in step S14 of the current loop process and the value of the previous MR sensor 85 acquired in step S14 of the previous loop process. The quantity Δx is determined. Further, the zoom lens 32 indicated by the difference between the current value of the zoom linear potentiometer 106 newly acquired in step S12 of the current loop process and the value of the previous zoom linear potentiometer 106 acquired in step S12 of the previous loop process. A displacement amount Δx ′ is obtained. Then, whether or not the MR sensor 85 is normal is determined based on whether or not the displacement amount Δx and the displacement amount Δx ′ satisfy the conditional expression (1) (step S16).

  If YES is determined in step S16, that is, if it is determined to be normal, the value of the MR sensor 85 captured in step S14 of the current loop processing is used as the displacement amount (displacement amount from the initial position) of the zoom lens 32. Is added to the initial position value to obtain the current position value of the zoom lens 32 (step S18).

  On the other hand, if NO is determined in step S16, that is, if it is determined that there is an abnormality, the value of the current zoom linear potentiometer 106 captured in step 12 of the current loop processing is used without using the value of the MR sensor 85. Is set as the value of the current position of the zoom lens 32 (step S20).

  When the process of step S18 or step 20 is completed, the process returns to step 12.

  Note that, in the case where YES is determined in step S16, that is, the MR sensor 85 is determined to be normal, NO may be determined in step S16 of the previous loop processing, that is, the MR sensor 85 is determined to be abnormal. This aspect occurs, for example, when a part of the magnetic ring 84 is broken and the MR sensor 85 transitions from a state facing the damaged part of the magnetic ring 84 to a state facing a normal part that is not damaged. . In order to cope with this case, if the MR sensor 85 is determined to be abnormal in step S16, the value of the zoom linear potentiometer 106 set as the value of the current position of the zoom lens 32 in step S20 (the value captured in step S12). ) Is set as the value of the initial position of the zoom lens 32, and the count value of the sub MPU 102 (value of the MR sensor 85) is reset to zero. As a result, if the MR sensor 85 is determined to be normal in step S16 of the next loop processing, the displacement amount value of the zoom lens 32 normally detected from the value of the MR sensor 85 in step S18 is set as the initial position value. The value of the current position can be obtained by adding to.

  As described above, in the above embodiment, a display unit such as an LED is installed in the drive unit or the like, and the display mode of the display unit is changed depending on whether the MR sensor 85 is determined to be normal or abnormal in step S16. The user may be able to recognize that an abnormality has occurred in the MR sensor 85 (the sensor used for detecting the zoom position has been switched). For example, the user can be informed that an abnormality has occurred in the MR sensor 85 by turning off the LED when normal, turning on or blinking when abnormal, or turning on or blinking when abnormal. be able to.

  In the above embodiment, when an abnormality occurs in a part of the detection range of the MR sensor 85, only the position of the zoom lens 32 in that range is obtained from the value of the zoom linear potentiometer 106. If the abnormality of the MR sensor 85 is detected even once in step S16 of FIG. 3 even in the detection range only, the position of the zoom lens 32 is obtained from the value of the zoom linear potentiometer 106 thereafter. Good.

  In step S16 of FIG. 3 in the above embodiment, whether the MR sensor 85 is normal (whether it is abnormal) is determined based on whether the conditional expression (1) is satisfied. You may determine by other conditions. For example, when the displacement amount Δx ′ obtained from the value of the zoom linear potentiometer 106 is not 0, if the displacement amount Δx obtained from the value of the MR sensor 85 is 0, the MR sensor 85 is abnormal (otherwise A determination condition for determining that the condition is normal or based on other conditions is also conceivable. Further, the above Δx and Δx ′ are obtained from the difference between the values of the MR sensor 85 and the zoom linear potentiometer 106 acquired in the loop processing before and after the loop processing in steps S12 to S20 in FIG. .DELTA.x and .DELTA.x 'can be calculated from the value of the MR sensor 85 and the value of the zoom linear potentiometer 106 for the amount of displacement of the zoom lens 32 from a predetermined time to the current time. It may not be obtained from the difference between values acquired in successive loop processes.

  Further, whether or not the MR sensor 85 is normal can be determined only by the output voltage of the MR sensor 85 without using the value of the zoom linear potentiometer 106. That is, the output voltage of the MR sensor 85 is detected (for example, the output voltage of the MR sensor 85 can be read by the main MPU 100 by an A / D converter). it can. For example, when the voltage of the MR sensor 85 is normal, the MR sensor 85 has a predetermined voltage width V1 (eg, ± 50 to 100 mV) with respect to a constant voltage (midpoint) V0 (eg, 2.5 V). If the MR sensor 85 (or magnetic ring) has a failure (a part of the magnetic ring is damaged), a sine wave cannot be obtained, and one side is crushed, or the voltage at the midpoint Takes a value that deviates from V0 (for example, 2.5V ± 50 mV when normal, but 1.5V ± 50 mV, etc.). By detecting such a voltage abnormality, the MR sensor 85 alone can be detected by the MR sensor 85 alone without comparison with the zoom linear potentiometer 106.

  In the above embodiment, the position sensor for detecting the position (absolute position) of the zoom lens 32 is used as an absolute position sensor and a relative position sensor, and the zoom linear potentiometer 106 and the relative position sensor are used as the absolute position sensor. Although the aspect using the MR sensor 85 as the position sensor has been shown, the types of the absolute type position sensor and the relative type position sensor are not limited to those shown in the above embodiment, and any type of sensor is used. The present invention can be applied even in an embodiment. In addition, the present invention is not applied to a position sensor that detects the position of the zoom lens 32 but to a position sensor that detects the position of a movable lens such as a focus lens other than the zoom lens when the absolute position sensor and the relative position sensor are used. Applicable.

  DESCRIPTION OF SYMBOLS 1 ... Lens apparatus, 14 ... 1st main body ring, 32 ... Zoom lens, 46A ... Cam pin, 48 ... Cam cylinder, 50 ... Zoom ring, 84 ... Magnetic ring, 85 ... MR sensor), 100 ... Main MPU, 102 ... Sub MPU, 104 ... A / D converter, 106 ... zoom linear potentiometer

Claims (4)

An optical system including a movable lens;
An absolute position sensor that detects the absolute position of the movable lens;
A relative position sensor for detecting a displacement amount of the movable lens;
The absolute position of the movable lens at a predetermined time is obtained from the absolute type position sensor, and the displacement amount of the movable lens from the absolute position to the current position is obtained from the relative type position sensor. Arithmetic means for detecting a current position of the movable lens based on a displacement amount;
In the position detection device of the lens device comprising:
The computing means is
The amount of displacement of the movable lens from a predetermined time to the present is obtained based on the value Δx ′ obtained based on the absolute position obtained from the absolute type position sensor and the amount of displacement obtained from the relative type position sensor. An abnormality detection means for detecting whether or not the relative position sensor is abnormal by comparing with a value Δx in the case of
When it is detected that the abnormality is detected by the abnormality detection unit, a detection position repair unit that uses the current absolute position acquired from the absolute position sensor as it is as the current position of the movable lens;
A position detection device for a lens device, comprising:   2. The position detecting device for a lens device according to claim 1, further comprising display means for displaying when an abnormality is detected by the abnormality detecting means.   The absolute position sensor includes a resistor to which a voltage is applied at both ends, and a sliding body that moves relative to the resistor and moves along a position along the resistor in conjunction with the movable lens. And a relative potentiometer that outputs a voltage corresponding to the position of the movable lens from the sliding body. The relative position sensor is a multipole permanent magnet body having N poles and S poles alternately magnetized. It is an MR sensor that moves relative to the multipolar permanent magnet body in conjunction with the movable lens and outputs a pulse signal having a number of pulses corresponding to the amount of displacement of the movable lens. The position detection device of the lens device according to claim 1 or 2. The abnormality detecting means determines that the relative position sensor is normal when the absolute value of the difference between the value Δx and the value Δx ′ is less than a predetermined value α, and determines that the value Δx and the value Δx ′ 4. The position detection device for a lens device according to claim 1, wherein the relative position sensor determines that the abnormality is present when the absolute value of the difference is equal to or greater than the predetermined value α .

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