JP4881828B2 - POSITIONING DEVICE, POSITIONING METHOD, AND OPTICAL DEVICE - Google Patents

Description

  The present invention relates to a positioning device that controls the position of a positioning object using a stepping motor, and an optical apparatus such as an imaging device or an interchangeable lens device that uses the positioning device for positioning a lens.

  In an optical apparatus, an actuator such as a stepping motor is used as a drive source in order to control driving of a lens such as a variable power lens or a focus lens with high positional accuracy. For this, a mechanism for driving the lens in the optical axis direction by a moving mechanism constituted by a rotating feed screw connected to a motor and a rack meshing with the screw is often used.

  Conventionally, this type of moving mechanism is configured as shown in FIG. In FIG. 6, 1 is an actuator such as a stepping motor, and 2 is a feed screw that is rotationally driven by the actuator 1. Reference numeral 3 denotes a rack which meshes with the feed screw 2 and linearly moves in the directions A and B by the rotation of the feed screw, and 5 is a support base. In the rack 5, the feed screw 2 is rotatably supported via a bearing member 6 between the vertical support walls 5 a and 5 b at both ends. The actuator 1 is attached to one vertical support wall 5b with a screw 7.

  The rack 3 includes a feed dog 3a that contacts the feed screw 2 and a pressing portion 3b that presses the feed screw 3a by spring pressure by a spring member (not shown), as shown in FIG. ing. Further, it is not always in contact with the feed screw, and is provided with an opposing tooth 3c provided so that the feed dog 3 does not get over the screw thread when an impact in the rack moving direction is applied.

  However, in such a rack structure, when a strong impact that greatly exceeds the elastic deformation strength of the rack is applied, a force that causes the feed dog 3 to get over the thread is applied, so that the feed dog 3a of the rack 3 and the counter tooth There is a possibility that the space 3c is elastically deformed and spreads. In this case, as shown in FIG. 8, the distance between the feed teeth 3 a and the opposing teeth 3 c of the rack 3 is widened to the point where the screw thread apex of the feed screw 2 and the apex of the opposing teeth 3 a are in contact with each other. In this state, if the opposing tooth 3c of the rack 3 is caught by the thread of the feed screw 2, the rack is less likely to move relative to the feed screw 2 even if the actuator 1 is driven. There was a problem that the phenomenon occurred.

  If such biting occurs, it becomes impossible to drive a variable power lens, a focus lens, or the like of the optical device. Then, the zooming and focusing operations necessary for the optical device cannot be performed, and the optical device becomes inoperable.

  The following is a conventional technique for such a problem of rack biting. A screw-free region is provided at least at one end of the feed screw. At the same time, the opposing tooth is provided at a position offset in the moving direction with respect to the feed dog. As a result, there has been proposed a structure in which the opposing teeth come to the region without the screw at the end of the movable range of the rack (see, for example, Patent Document 1 (page 4 FIGS. 1 to 3)).

In this conventional example, in the case where biting occurs when the rack 3 hits the end of the movable range, an area without the screw 2 is provided at the end of the feed screw so as not to hit the counter teeth. The structure is difficult to generate.
Japanese Patent Laid-Open No. 9-258087

  However, in the above-described conventional example, the effect that biting is difficult to occur is obtained only at the end portion of the feed screw, which is a region without a screw. On the other hand, when performing the zooming operation and focusing operation necessary for the optical equipment as described above, the rack is usually in an intermediate region within the moving range, and the rack is subjected to an impact from the outside. There was a drawback that the effect was not obtained for the occurrence of biting.

  As described above, in the prior art, when the rack is in a limited position (the end of the feed screw), it is possible to obtain an effect that the rack biting hardly occurs, but in other cases There was a problem that it was insufficient to prevent the optical device from becoming inoperable.

  An object of the present invention is to appropriately detect a reference position even when a rack bite due to an external impact or the like occurs regardless of the position of the rack with respect to the feed screw.

One aspect of the present technical idea is that the positioning device rotates the feed screw by a positioning object, a moving means that moves the positioning object by a moving mechanism having a rotating feed screw and a rack that meshes with the positioning object, and a stepping motor. A driving means; a reference position detecting means for detecting a reference position of the positioning object; a control means for controlling the driving means; and the feed screw and the rack bite when the reference position is detected by the reference position detecting means. And a biting discrimination means for discriminating that the movement cannot be performed. When the biting judgment means determines that the feed screw and the rack are biting, the control means calculates the driving torque of the driving means. it reaches to the clip state does not change when the voltage level is increased than when it is not determined that with eating Controls, the detection of the cause again standards position reducing the drive torque when the reference position after having increased to reach the driving torque to the clip state is detected performed.

In another aspect, the positioning object, moving means for moving the positioning object by a moving mechanism having a rotating feed screw and a rack meshing therewith, driving means for rotating the feed screw by a stepping motor, and the positioning A reference position detecting means for detecting a reference position of an object, a control means for controlling the driving means, and a state in which the feed screw and the rack are bitten and cannot move when the reference position is detected by the reference position detecting means A positioning method using a positioning device provided with a biting discrimination means for discriminating whether the feed screw and the rack are biting by the biting judgment means, the control means is the drive clip does not change the voltage level is increased than when it is not determined that with eating the driving torque means It controls to so that to reach a state, the detection of the cause again standards position reducing the drive torque when the reference position after having increased to reach the driving torque to the clip state is detected.

  According to the present technical idea, it is possible to appropriately detect the reference position even when the rack bites due to an external impact or the like, regardless of the position of the rack with respect to the feed screw.

  Examples for carrying out the technical idea of the present application are shown as those described in Examples 1 and 2 below.

  FIG. 1 is a diagram showing a configuration of a first embodiment in a case where the technical idea of the present application is applied to an optical apparatus, particularly an imaging apparatus such as a video camera.

  This imaging apparatus includes a field lens 101, a variator lens 102 as a variable power lens, an aperture unit 114 for adjusting the amount of light, an afocal lens 103, and a focus lens 104 from the subject side (left side in the figure). It has a photographing optical system. Reference numeral 116 denotes an image sensor such as a CCD sensor or a CMOS sensor that photoelectrically converts a subject image formed by the photographing optical system.

  The variator lens 102 and the focus lens 104 are held by lens holding frames 105 and 106, respectively. These lens holding frames 105 and 106 are guided in the optical axis direction by a guide shaft (not shown).

  In addition, racks 105a and 106a are attached to the lens holding frames 105 and 106, respectively. The racks 105a and 106a mesh with screw portions (screw portions) of screw shafts (screw shafts) 107a and 108a that are output shafts of the stepping motors 107 and 108. When each stepping motor is driven and the screw shaft rotates, the lens holding frame is driven in the optical axis direction (the arrow direction in the figure) by the meshing action of the screw shaft and the rack.

  When the variator lens 102 and the focus lens 104 are driven to their respective target positions by the stepping motors 107 and 108 as described above, the lens is first set to a position (reference position) that serves as a reference for position control when the imaging apparatus is activated. A drive signal having the number of pulses necessary to move from the reference position to the target position is input to the stepping motor. For this reason, the imaging apparatus is provided with a reference position sensor for detecting whether or not the variator lens 102 and the focus lens 104 are respectively positioned at the reference position. In this embodiment, the reference position sensor is constituted by photo interrupters 109 and 110 in which a light emitting element and a light receiving element are integrated. The reference position detection process at this time will be described in detail later.

  Whether or not the variator lens 102 and the focus lens 104 are positioned at the reference position is detected as follows. Light shielding portions 105b and 106b provided in the lens holding frames 105 and 106 enter between the light emitting elements and the light receiving elements of the photo interrupters 109 and 110, respectively. If it does so, the output from a reference position sensor will change from High to Low by blocking the light which goes to a light receiving element from a light emitting element. Thereby, it is detected that the variator lens 102 and the focus lens 104 are positioned at the reference position.

  The light shielding member 105b has a shape that enables zone detection on the telephoto side or the wide angle side of the variator lens 102. For example, a light shielding member 105b is provided in the telephoto zone. The light shielding member 106b has a shape that enables zone detection to determine whether the focus lens 104 is focused on a long-distance object or whether it is focused on a close object. For example, a light shielding member 106b is provided in a zone that focuses on a long-distance object.

  A microprocessor 111 serving as a control unit controls the overall operation of the imaging apparatus in accordance with inputs from switches such as a power switch, a recording switch, and a zoom switch (not shown). In the internal memory 112 provided in the microprocessor 111, the telephoto side and wide angle side positions with respect to the reference position of the variator lens 102 are stored as the number of steps corresponding to the rotation amount of the stepping motor 107. Also for the reference position of the focus lens 104, position data determined by the object distance and the position of the variator lens 102 is stored as the number of steps corresponding to the rotation amount of the stepping motor 108.

  The stepping motors 107 and 108 are driven in accordance with forward and reverse signals from the microprocessor 111 input to the stepping motor drive circuits 119 and 120, respectively. In other words, the zooming operation of the imaging optical system and the focusing operation associated therewith are performed by controlling the stepping motors 107 and 108 by an electronic cam system using cam data generally used in video cameras and the like. . Note that the driving method of the stepping motor used in the present embodiment is not particularly limited, and may be a 1-2 phase driving method or a 2-2 phase driving method.

  The diaphragm unit 114 includes a so-called galvano-type actuator 113, diaphragm blades 114a and 114b that are driven to open and close by the actuator 113, and a position detection element (Hall element) 115 that detects the aperture opening / closing state.

  As described above, the variator lens 102 and the focus lens 104 are controlled based on the reference position, and subject light that has passed through other optical elements such as the aperture unit 114 reaches the image sensor 116. An electrical signal from the image sensor 116 that converts subject light such as a CCD or CMOS into an electrical signal is converted from an analog signal to a digital signal by the A / D conversion circuit 117 and input to the signal processing circuit 118. The signal processing circuit 118 sends a video signal to the recording unit 150 from the input electrical signal. The microprocessor 111 feedback-controls the actuator 113 so that the input luminance signal component always has an appropriate value. At this time, the output from the position detection element 115 is amplified to the microprocessor 111, and further converted from an analog signal to a digital signal by the A / D conversion circuit 123 and input as information indicating the opening / closing position of the diaphragm. Based on the aperture position information, the microprocessor 111 sends an open / close signal to the drive circuit 121 to control the actuator 113 so that the luminance signal component always has an appropriate value. From the microprocessor 111, an opening / closing signal for positioning the aperture position at a predetermined opening / closing position can also be sent to the drive circuit 121.

  Hereinafter, a process for determining whether or not the biting has occurred when the reference position is detected by the reference position sensor, and when the biting has occurred, a process for increasing the driving torque of the stepping motor will be described. In the following description, a variator lens will be described as a positioning object, but the same can be applied to a focus lens.

  FIG. 2 shows the sensor output of the photo interrupter 109 as a reference position sensor with respect to the position of the variator lens 102. The movable range of the variator lens 102 is defined by the stopper positions on the wide-angle side and the telephoto side. The photo interrupter 109 and the light shielding portion 105b are provided as follows. That is, when the variator lens 102 is in the section L1 from the reference position shown in FIG. 3 to the wide-angle side stopper position, the sensor output of the photo interrupter 109 is a signal output that is determined to be high level by the microprocessor 111. Further, when the variator lens 102 is in the section L2 from the reference position to the telephoto stopper position, the sensor output is a signal output that is determined to be a low level. Accordingly, the microprocessor 111 detects whether the sensor output of the photo interrupter 109 is at a high level or a low level, so that it can be determined whether the variator lens 102 is on the wide-angle side or the telephoto side from the reference position. It has become.

  Hereinafter, the reference position detection process, the biting determination process, and the process for increasing the drive torque will be described with reference to the flowchart of FIG. These processes are controlled by the microprocessor 111 unless otherwise specified.

  First, the process of detecting the reference position by the reference position sensor will be described below. When the imaging apparatus is activated, the reference position detection process is started. The reference position detection process is also started when the mode is changed from a mode other than the imaging mode such as the reproduction mode to the imaging mode. In STEP 301, the driving speed of the stepping motor 107 for driving the variator lens 102 is set to V1. This speed V1 is faster than the time of imaging in order to detect the reference position in a short time. Next, in STEP 302, the power rate, which is a parameter for setting the drive voltage of the stepping motor 107, is set to P1. Here, the power rate will be described with reference to FIG. A stepping motor used for lens control uses so-called micro-step driving in order to make the resolution of the stop position fine. In this case, as shown in FIG. 5 (a), the voltage (A phase, B phase) applied to the coil of the two-phase driving stepping motor is a two-phase sine wave whose phase is shifted by 90 °. The stepping motor drive circuit 119 performs control based on a control command from the microprocessor 111. Here, the power rate is the ratio of the amplitude of the sine wave voltage of the microstep drive to the maximum positive and negative voltage that can be generated by the stepping motor drive circuit 119. In FIG. 5 (a), since both coincide, the power rate is 100%. Since the coil current of the stepping motor increases as the power rate is increased, a high torque can be generated. However, in microstep driving, driving is performed at a power rate of 100% or less so that the driving waveform is not clipped by the maximum voltage of the driving circuit, so the power rate P1 set in STEP 302 is set to 100% or less. This is for obtaining positioning accuracy.

  Next, in STEP 303, it is determined whether the sensor output of the photo interrupter 109, which is a reference position sensor, is High level or Low level. If it is determined that the level is high, the variator lens 102 is on the wide-angle side from the reference position as shown in FIG. 2, and therefore, the process proceeds to STEP 304 and the variator lens is driven to the telephoto side. Then, in STEP 305, it is determined whether or not the reference position sensor has changed to Low, and if it becomes Low, the process proceeds to STEP 311 because the reference position has been detected. Then, the driving of the variator lens is stopped and the reference position detection process is ended.

  On the other hand, if it is determined in STEP 303 that the sensor output of the photo interrupter 109 is at the low level, the variator lens 102 is on the telephoto side from the reference position, so that the process proceeds to STEP 312 and the variator lens is driven to the wide angle side. Then, in STEP 313, it is determined whether or not the reference position sensor has changed to High. If it becomes High, the process proceeds to STEP 311 because the reference position has been detected. Then, the driving of the variator lens is stopped and the reference position detection process is ended. The above is the normal reference position detection process when no biting occurs.

  Next, a process for determining whether biting has occurred in the reference position detection process will be described. When it is determined in STEP 304 and STEP 305 that the reference position sensor has not changed to Low while the variator lens is being driven to the telephoto side, the following is performed. That is, in STEP 306, it is determined whether or not the movement distance of the variator lens after the start of the reference position detection process is longer than the length L1 of the section from the reference position to the wide-angle stopper position shown in FIG. Here, the moving distance of the variator lens can be obtained by integrating the number of pulses generated by the stepping motor drive circuit 119 after the start of the reference position detection process. That is, it is a movement distance based on the number of pulses generated by the stepping motor drive circuit 119, not the actual movement distance of the variator lens. The movement distance based on the number of pulses generated by the stepping motor drive circuit 119 corresponds to the actual movement distance of the variator lens if no biting occurs.

  As can be seen from FIG. 2, regardless of the initial position of the variator lens from the reference position to the wide-angle stopper position when the reference position detection process is started, the variator lens until the reference position is detected is detected. The moving distance to the telephoto side should be less than L1. However, when the biting occurs and the variator lens cannot move even when the stepping motor driving circuit 119 applies the driving pulse to the stepping motor, the reference position cannot be detected. This corresponds to the fact that the reference position cannot be detected even if the moving distance of the variator lens obtained by integrating the number of pulses is L1 or more. Therefore, it is possible to determine whether or not biting has occurred by determining whether or not the moving distance is equal to or greater than L1 in STEP 306. If the moving distance is less than or equal to L1, the process returns to STEP 304 and continues driving to the telephoto side.

  Next, when it is determined in STEP 306 that the biting has occurred, a process of increasing the driving torque of the stepping motor 107 and removing the hook between the opposing teeth of the rack and the thread of the feed screw will be described. When it is determined in STEP 306 that the bite has occurred, the process proceeds to STEP 307 and the drive speed of the stepping motor 107 is set to V2. Here, the driving speed V2 is set to a speed slower than the driving speed V1 set in STEP301. By changing the driving speed to V2, it is possible to increase the driving torque of the stepping motor 107 and to easily remove the hook between the opposing teeth of the rack and the thread of the feed screw. This is because the stepping motor has a characteristic capable of generating a large torque when the driving speed is low.

  In STEP 308, the power rate is set to P2. Here, the power rate P2 is set to a value larger than the power rate P1 set in STEP302. When the power rate is set to a value larger than 100%, as shown in FIG. 5B, the drive waveform of the stepping motor 107 is clipped by the maximum voltage of the drive circuit and becomes a waveform close to a square wave. In this case, although micro-step driving cannot be performed, the average voltage and current applied to the stepping motor 107 increase, so that the driving torque is increased and the rack facing teeth and the feed screw threads are increased. Can be more easily removed.

  As described above, after setting the driving condition so as to increase the driving torque of the stepping motor 107, the variator lens is further driven to the telephoto side in STEP309. In STEP 310, it is determined whether or not the reference position sensor has changed to Low. If not changed, the process returns to STEP 309 to continue driving the variator lens. On the other hand, if it is determined that the reference position sensor has changed to Low, the drive torque is increased so that the hook between the opposing teeth of the rack and the thread of the feed screw is released, and the rack can be returned to normal operation. Can be considered. However, since the power rate is set to a value larger than 100%, microstep driving is not performed. Therefore, since the position resolution of the reference position detection is low, the process returns to STEP 301 and the reference position detection process is resumed. Note that the accumulated data of the number of pulses generated by the stepping motor drive circuit 119, which is used to obtain the movement distance of the variator lens after the start of the reference position detection process in STEP 306 and STEP 314, is initialized.

  Here, the reason for performing the reference position detection process again after setting the power rate to a value larger than 100% and increasing the drive torque will be described. In microstep driving, driving is performed using a two-phase sine wave as shown in FIG. 5a. If it is 100% or less, the A-phase and the B-phase are continuously changing, and therefore can be continuously stopped at an arbitrary position. Although the horizontal axis in the figure represents time, it can also be understood from the fact that when viewed as zoom positions, the voltage levels of the A phase and B phase are uniquely determined for each zoom position. However, when it becomes 100% or more, the A phase and the B phase are clipped as shown in FIG. In particular, in the section where both the A phase and the B phase are clipped, the voltage levels of the A phase and the B phase do not change with respect to the zoom position, so the zoom position cannot be controlled in this section. As a result, the positioning accuracy deteriorates, so it is necessary to increase the positioning accuracy by reducing the driving torque. For this reason, the power rate is set to 100% or more only in an emergency situation of returning from biting, and is returned to 100% or less after returning from biting. In this way, the control is performed such that the drive torque is reduced and the reference position detection process is restarted again.

  STEP 314 to STEP 318 are biting determination processing and processing for increasing the driving torque when the sensor output of the photo interrupter 109 is determined to be low level in STEP 303. If it is determined in STEP 313 that the reference position sensor has not changed to High while the variator lens is being driven to the wide angle side, STEP 314 is followed. In STEP 314, it is determined whether or not the movement distance of the variator lens after the start of the reference position detection process is longer than the length L2 of the section from the reference position shown in FIG. 2 to the telephoto stopper position. Similarly to the description regarding STEP 306 described above, it is possible to determine whether or not biting has occurred by determining whether or not the movement distance is L2 or more. If it is determined in STEP 314 that biting has occurred, the driving speed of the stepping motor 107 is set to V2 and the power rate is set to P2 in STEP 315 and STEP 316, and the driving torque of the stepping motor 107 is increased. In STEP 317, the variator lens is further driven to the wide angle side, and in STEP 317, it is determined whether or not the reference position sensor has changed to High. If it is not changed to High, the process returns to STEP 317 to continue driving the variator lens. If it has changed to High, similarly to STEP 310, the accumulated data of the number of pulses generated by the stepping motor drive circuit 119 is initialized, and the process returns to STEP 301 to perform the reference position detection process again. This is because if the power rate is set to a value larger than 100% as described above, there is a high possibility that there is an error even if the reference position can be detected.

  The processing described above is executed by the microprocessor 111 that controls the driving of the stepping motor 107, thereby determining whether or not the biting has occurred when the reference position is detected by the stepping motor reference position sensor. And when the biting has occurred, the driving torque of the stepping motor can be increased. As a result, even when the rack bites due to an impact from the outside or the like, the rack can be forcibly moved to remove the hook between the opposing teeth of the rack and the thread of the feed screw. Therefore, the phenomenon that the optical device becomes inoperable due to the biting of the rack can be made difficult to occur.

  Next, a description will be given of a second embodiment in which the positioning device according to the present technical idea is applied to an imaging apparatus in the same manner as the first embodiment. Since the configuration of the imaging apparatus according to the second embodiment is the same as that of the first embodiment, the description thereof is omitted.

  Hereinafter, the biting determination process and the process of increasing the driving torque in the second embodiment will be described with reference to the flowchart of FIG. The control processing shown in this flowchart is controlled based on instructions from the microprocessor 111 unless otherwise specified.

  The processing for detecting the reference position by the reference position sensor is the same as in the first embodiment. Description of STEP 401 to STEP 405, STEP 413, and STEP 414 to STEP 415 related to this process is omitted. This is because the processing is the same as STEP 301 to STEP 305, STEP 311 and STEP 312 to STEP 313 in FIG.

  In Example 1, in STEP 306, whether or not the movement distance of the variator lens 102 after the start of the reference position detection process is larger than the length L1 of the section from the reference position to the wide-angle side stopper position shown in FIG. Was determined. Thereby, it was determined whether or not biting occurred. On the other hand, in Example 2, it is determined in STEP 406 whether or not the movement time of the variator lens after the start of the reference position detection process is larger than the threshold value T1. Thereby, it is determined whether or not biting has occurred.

  In this respect, the moving distance of the variator lens is determined by the driving speed V1 set in STEP 401 and the moving time. From this, if T1 ≧ (L1 / V1), it is equivalent to determining whether or not the bite occurs in STEP 306 of Example 1 depending on whether or not the moving distance of the variator lens is larger than L1.

  Here, as for the movement time of the variator lens, the time after the start of the reference position detection process by the timer function of the microprocessor 111 or the like may be measured. Further, since the control process of the imaging device is executed in a cycle synchronized with the vertical synchronization signal of the video signal, it may be obtained by counting the number of loops of the control process after the start of the reference position detection process.

  If the movement time is equal to or shorter than T1 in STEP 406, the process returns to STEP 404 and the driving to the telephoto side is continued. On the other hand, if the moving time is longer than T1, it is determined that biting has occurred, and in STEP 407 and STEP 408, the driving speed of the stepping motor 107 is set to V2 and the power rate is set as in STEP 307 and STEP 308 of the first embodiment. Set to P2. Thereby, the driving torque of the stepping motor 107 is increased. In STEP 409, the variator lens is further driven to the telephoto side, and in STEP 410, it is determined whether or not the reference position sensor has changed to Low. If it has changed to Low, it can be considered that the rack has been recovered so that the rack can operate normally by increasing the driving torque so that the opposing teeth of the rack and the thread of the feed screw are released. Therefore, returning to STEP 401, the reference position detection process is resumed. This is because if the power rate is set to a value larger than 100% as described above, there is a high possibility that there is an error even if the reference position can be detected.

  In step 406 and step 416, the timer value or count value used to start the reference position detection process and obtain the subsequent movement time of the variator lens is initialized.

  On the other hand, if the reference position sensor has not changed to Low in STEP 410, it is determined in STEP 411 whether or not the movement time of the variator lens is greater than the threshold value T3. This is because, depending on the state of the rack biting, even if the driving torque of the stepping motor 107 is increased, the hook between the opposing teeth of the rack and the thread of the feed screw may not be released. When the stepping motor is driven at a high torque for a long time in such a state, the following problems occur. In other words, there is a high possibility that the lens moving mechanism is destroyed by excessive driving, or that a large current continues to flow through the stepping motor to generate heat and damage the imaging device. Further, if the stepping motor 107 is continuously driven in one direction, the pulse counter of the logic circuit for driving the motor may overflow and normal driving may not be performed. Therefore, the driving time in which there is no fear of the occurrence of destruction, heat generation, or pulse counter overflow as described above is measured in advance. A threshold value T3 is set based on the measurement result. If it is determined in STEP 411 that the moving time of the variator lens is larger than the threshold value T3, the driving of the stepping motor 107 is stopped in STEP 412. In this case, since it is not possible to return from biting, it is determined that there is an error in the reference position detection process, and the process is stopped. If it is determined in STEP 411 that the moving time of the variator lens is smaller than the threshold value T3, the process returns to STEP 409 and the driving to the telephoto side is continued.

  Here, in the flowchart of FIG. 4, T1 and T2 are different in the branching on the telephoto side and the wide-angle side, while T3 is the same on the telephoto side and the wide-angle side. This is because T3 is a set time for preventing the destruction of the moving mechanism, for example, the destruction of the screw thread, the damage of the rack, or the overflow of the pulse counter of the logic circuit for driving the motor. Further, since T3 is not related to the moving direction, it has the same value on the telephoto side and the wide-angle side in common. Therefore, T3 is longer than T1 and T2.

  STEP 416 to STEP 421 are processes for determining the bite and increasing the driving torque when the sensor output of the photo interrupter 109 is determined to be at the low level in STEP 403. If it is determined in STEP 415 that the output from the reference position sensor has not changed to High while the variator lens is being driven to the wide angle side, the process proceeds to STEP 416. In STEP 416, it is determined whether or not the movement time of the variator lens after the start of the reference position detection process is larger than the threshold value T2. Similarly to the description regarding STEP 406 described above, if T2 ≧ (L2 / V1), in STEP 314 of Example 1, it is determined whether or not the bite has occurred depending on whether the moving distance of the variator lens is greater than L2. It becomes equivalent. If it is determined in STEP 416 that biting has occurred, the driving speed of the stepping motor 107 is set to V2 and the power rate is set to P2 in STEP 417 and STEP 418. Thereby, the driving torque of the stepping motor 107 is increased. Then, in STEP 419, the variator lens is further driven to the wide angle side, and in STEP 420, it is determined whether or not the output from the reference position sensor has changed to High. If it has changed to High, the timer value or count value is initialized in the same manner as in STEP 410, the process returns to STEP 401, and the reference position detection process is resumed. This is because if the power rate is set to a value larger than 100% as described above, there is a high possibility that there is an error even if the reference position can be detected.

  On the other hand, if it is not changed to High, it is determined whether the moving time of the variator lens is larger than the threshold value T3 as in STEP411. If it is determined that it is larger, the driving of the stepping motor 107 is stopped in STEP 412, and it is determined that the error is in the reference position detection process, and the process is stopped. On the other hand, when it is determined that the moving time is smaller than the threshold value T3, the process returns to STEP 419 and the driving to the wide angle side is continued.

  The processing in STEPs 411 and 412 in the second embodiment can also be applied to the processing in the first embodiment. That is, the driving may be performed at the power rate P2 by limiting to T3.

  The processing described above is executed by the microprocessor 111 that controls the driving of the stepping motor 107. Thus, as in the first embodiment, it is determined whether or not biting has occurred when the reference position is detected by the stepping motor reference position sensor. And when the biting has occurred, the driving torque of the stepping motor can be increased. As a result, even when the rack is bitten by an external impact or the like, the rack can be forcibly moved to remove the hook between the opposing teeth of the rack and the thread of the feed screw. Further, it is possible to make it difficult for the phenomenon that the optical apparatus becomes inoperable due to the biting of the rack. Furthermore, if the stepping motor cannot be recovered from the bite even if the stepping motor is driven for a time longer than a predetermined threshold, the imaging device can be destroyed by driving the stepping motor with a large torque for a long time by stopping the driving It is possible to prevent overheating.

  As described above, when a rack bite due to an external impact or the like occurs, it is determined whether the bite has occurred when the reference position is detected by the reference position detection means. When biting occurs, the driving torque of the stepping motor is increased. Thus, the rack can be forcibly moved, and the hook between the opposing teeth of the rack and the thread of the feed screw can be removed. Note that the catch may not be released depending on the drive torque limit of the stepping motor and the catching state of the opposing teeth and the thread. In this respect, if it is a slight bite, it can be removed as described above. As a result, the rack can be restored to operate normally. Therefore, regardless of the position of the rack with respect to the feed screw, the phenomenon that the optical device becomes inoperable due to the biting of the rack can be made difficult to occur.

  Further, when the stepping motor is driven for a time equal to or greater than a predetermined threshold value, the driving is stopped when it cannot be recovered from the biting. Accordingly, it is possible to prevent the optical device from being broken or overheated by driving the stepping motor with a large torque for a long time.

It is a figure which shows the structure of Example 1 at the time of applying to an imaging device. It is a figure which shows the sensor output of the photo interrupter 109 which is a reference | standard position sensor with respect to the position of the variator lens. It is a figure which shows the sensor output of the photo interrupter 109. FIG. It is a figure which shows the process which increases the biting discrimination | determination process and drive torque in Example 2. FIG. It is a figure which shows the power rate of the stepping motor. It is a figure which shows the mechanism which drives a lens to an optical axis direction. It is the figure which looked at the mechanism which drives a lens to an optical axis direction from the Z direction of FIG. It is a figure which shows the mechanism which drives a lens to an optical axis direction.

Explanation of symbols

101 Field lens 101
DESCRIPTION OF SYMBOLS 102 Variator lens 114 Aperture unit 103 Afocal lens 104 Focus lens 116 Image pick-up element 105, 106 Lens holding frame 105a, 106a Rack 106a
107, 108 Stepping motor 107a, 108a Screw shaft (screw shaft)

Claims (11)

A positioning object, a moving means for moving the positioning object by a moving mechanism having a rotating feed screw and a rack meshing therewith, a driving means for rotating the feed screw by a stepping motor, and a reference position of the positioning object are detected. A reference position detecting means for controlling, a control means for controlling the driving means, and a bite for determining that the feed screw and the rack are in a state where they cannot move when the reference position is detected by the reference position detecting means. It is equipped with a date discrimination means,
When it is determined that the feed screw and the rack are biting by the biting determination means, the control means increases the driving torque of the driving means compared to the case where it is not determined that it is biting, and the voltage level does not change and the clip state is maintained. characterized by performing controls on so that to reach the detection of the cause again standards position reducing the drive torque when the reference position after having increased to reach the driving torque to the clip state is detected A positioning device.   The rack includes at least one feed dog in contact with the feed screw and a pressing portion that presses the feed dog against the feed screw, and the biting occurs when the rack and the feed screw are caught. The positioning device according to claim 1.   When the biting determination means cannot detect the reference position even if the stepping motor performs driving corresponding to a movement distance longer than a predetermined distance after the movement of the positioning object is started by the driving means. The positioning device according to claim 1, wherein it is determined that the feed screw and the rack are biting.   The positioning device according to claim 3, wherein the predetermined distance is based on a movable range of a positioning object and the reference position.   The bite judging means bites the feed screw and the rack when the reference position cannot be detected even if the stepping motor is driven in a predetermined time after starting the movement of the positioning object. The positioning device according to claim 1, wherein:   6. The positioning apparatus according to claim 5, wherein the predetermined time is based on a movable range of the positioning object, the position of the reference position, and a speed when the positioning object moves.   7. The control device according to claim 1, wherein, when the biting determination unit determines that the feed screw and the rack are biting, the control unit makes the driving speed of the driving unit slower than before. The positioning device according to any one of claims.   The control means increases the voltage or current applied to the driving means when the biting judgment means judges that the feed screw and the rack are biting. The positioning device according to claim 1.   When it is determined that the feed screw and the rack are biting by the biting determination unit, the control unit further drives the stepping motor for a predetermined time even in the increase of the driving torque, The positioning apparatus according to claim 1, wherein the driving is stopped. A positioning object, a moving means for moving the positioning object by a moving mechanism having a rotating feed screw and a rack meshing therewith, a driving means for rotating the feed screw by a stepping motor, and a reference position of the positioning object are detected. A reference position detecting means for controlling, a control means for controlling the driving means, and a bite for determining that the feed screw and the rack are in a state where they cannot move when the reference position is detected by the reference position detecting means. In the positioning method using the positioning device provided with the sticking judging means, the control means eats the driving torque of the driving means when it is judged by the biting judging means that the feed screw and the rack are biting. so that to reach the clip state does not change when the voltage level is increased than when it is not determined are Controls, positioning method, characterized in that the detection of the cause again standards position reducing the drive torque when the reference position after having increased to reach the driving torque to the clip state is detected.   An optical apparatus that positions an optical element and moves the positioned optical element by the positioning device according to claim 1.

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