JP2006042408A - Linear actuator and optical instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To take an effective lubricating action by suppressing, in view of temperature and humidity, the number of times of lubricating action to be performed to eliminate the unevenness of sliding oil applied on a section where a mobile part and a fixed part contact with each other, in a linear actuator. <P>SOLUTION: This linear actuator, which has a magnet and a drive coil for driving a mobile part and generates thrust for driving the above mobile part by the current application to the drive coil, has an environmental condition detecting means which detects environmental conditions, and a lubricating action control means which decides the number of times of lubricating action for removing unevenness in drive of the mobile part from the detection results of the environmental condition detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lubricating operation of a linear actuator that is applied to driving of a photographing lens and driving of a machine tool.

There is a tendency that the drive control is also highly accurate due to the recent high precision and miniaturization of various devices. For example, some video cameras or the like perform drive control of the taking lens using a linear actuator in order to satisfy the above needs. Since the linear actuator can directly drive a moving object, it is not necessary to transmit a driving force by a gear or a screw. Therefore, it is possible to reduce the size and noise of the device. When drive control is performed using such a linear actuator, a certain amount of friction is required at the contact portion between the moving portion and the fixed portion that supports the moving portion. Due to this friction, a brake acts passively on the moving part, so that highly accurate position control and speed control can be performed. Generally, sliding oil is applied to the contact portion in order to maintain this friction.
JP 2002-350716 A

  However, the viscosity of the sliding oil varies depending on environmental conditions such as temperature and humidity. In particular, since the viscosity of the sliding oil increases in a low temperature state, the permeability to the contact portion between the moving part and the fixed part of the apparatus decreases, and unevenness of the sliding oil in the moving range occurs. In addition, when using a limited part of the moving area frequently and using the remaining part in an extremely low frequency, friction between the moving area with high usage and the moving area with low usage There will be a difference. Such frictional unevenness causes deterioration of control performance and generation of abnormal noise, so that a lubrication operation is required to make the sliding oil familiar. Generally, the lubrication operation is performed during the start-up operation immediately after the power is turned on. However, if the lubrication operation time is too long, the start-up takes time, and if the lubrication operation time is too short, frictional irregularities remain.

  In order to solve the above-described problem, the invention according to claim 1 includes a magnet and a drive coil for driving the moving unit, and generates a thrust for driving the moving unit by energizing the drive coil. The linear actuator includes an environmental condition detection unit that detects an environmental condition, and a lubrication operation control unit that determines the number of lubrication operations for eliminating drive unevenness of the moving unit from the detection result of the environmental condition detection unit. is doing. The environmental conditions here are temperature and humidity. According to a fifth aspect of the present invention, in an optical device having a photographic lens and a linear actuator for moving the photographic lens, it is possible to eliminate driving unevenness of a moving unit including the photographic lens and a holding member for the photographic lens. During the lubrication operation, a movement range larger than the lens movement range that is moved during photographing is moved to perform the lubrication operation.

  In linear actuators, the lubrication operation performed to eliminate unevenness of the sliding oil applied to the mating part of the moving part and the fixed part is performed by taking the lubrication operation as many times as necessary in consideration of temperature and humidity. Smooth lubrication operation can be reduced, and an efficient sliding operation can be realized. As a result, the frictional unevenness of the fitting portion is eliminated, the linear actuator can be driven smoothly, and highly accurate position control or speed control is possible.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking a linear actuator mounted in a video camera system as an example.

  FIG. 1 shows an optical device equipped with a linear actuator. In the case of a linear actuator, there are a moving coil type in which a coil is arranged on the movable side and a moving magnet type in which a magnet is arranged on the movable side. Here, the moving coil type will be described as an example. The reset sensor 100 attached to the fixed lens barrel 109 is, for example, a photo interrupter, and is shielded by a light shielding plate provided integrally with the bearing 102, whereby a change occurs in the reset sensor output, and this change is triggered. The position information is detected. The obtained position information becomes a reference position and is used for obtaining an absolute position. Further, when the position information is, for example, an optical position sensor, the position information is detected using an optical scale fixed to the bearing 102 and a position sensor 105 including a light emitting element and a light receiving element. ° Outputs position signals such as B phase with different phases. The moving part is supported by a guide bar 101, and sliding oil is applied to a fitting portion between the guide bar 101 and the bearing 102. The yoke 106, the magnet 107, and the coil 108 constitute a voice coil motor, and when a current is passed through the coil 108, a thrust for driving the moving unit in the optical axis direction is generated.

  FIG. 2 shows a block configuration of the video camera. Reference numerals 200, 201, 203, and 204 denote photographing lens groups, 200 denotes a fixed front lens group, 201 denotes a zoom lens group, 203 denotes a fixed lens group, and 203 denotes a focus lens group. The position of the zoom lens group 201 can be detected by the zoom encoder 209. The types of zoom encoders include, for example, a volume resistor configured such that a brush integrally attached to the zoom moving unit slides on a substrate on which a resistance pattern is printed, or an optical attached to the zoom moving unit. For example, there is a position detection sensor that optically detects a pattern carved on an optical scale by a light emitting unit and a light receiving unit arranged on the fixed lens barrel side. When the zoom switch 217 is operated, the CPU 216 captures the operation signal and sends the drive signal to the zoom drive unit 208, whereby the zoom lens group 201 can be moved. Reference numeral 202 denotes an IRIS that adjusts the amount of light, and the aperture value is detected by the aperture encoder 211. The diaphragm encoder 211 detects, for example, the output of a Hall element provided in the IRIS. The CPU 216 drives the IRIS by giving a driving signal to the IRIS driving unit. The focus lens group 204 is driven by a drive signal from the CPU 216 via a focus drive unit, and the position at that time is detected by the focus encoder 213. For example, a focus encoder is a position sensor that optically detects a pattern engraved on an optical scale by a light emitting unit and a light receiving unit disposed on the fixed barrel side with respect to an optical scale attached to a focus moving unit. A sensor that detects the position of the magnetic pattern magnetized at a predetermined pitch by detecting a change in the magnetoresistive element is conceivable. In addition to the linear actuator, a DC motor or a stepping motor may be used for driving the zoom lens group and the focus lens group. The subject light passes through the photographing lens group and is detected by the image sensor 205 such as a CCD. The image sensor 205 is driven by a command from the CCD drive circuit 214. Further, the video signal detected by the image sensor 205 is sent to the signal processing circuit 206. The signal processing circuit 206 performs predetermined amplification and gamma correction on the output of the image sensor 205. The Y signal of the video signal processed by the signal processing circuit is sent to the AF signal processing 215 to be used for autofocus determination. In AF signal processing 215, in-focus or out-of-focus is determined, and the determination result is captured by the CPU 216. During autofocus, the focus lens is driven according to this determination. A zoom tracking memory 218 stores position information of a focus lens group to be set according to the subject distance and the zoom lens position at the time of zooming. Note that the memory in the CPU 216 may be used as the zoom tracking memory. Reference numeral 207 denotes a temperature or humidity sensor whose output potential changes in proportion to the environmental change. The CPU 216 reads the output change of the temperature or humidity sensor 207 to obtain temperature information and humidity information.

  FIG. 3 is a flowchart for explaining the operation according to the present invention. Here, a case where the present invention is applied for driving a focus lens will be described.

  The lubrication operation is started, for example, by an initial startup operation immediately after the user turns on the apparatus.

[Step 101]
First, a position reset is performed in order to determine a reference position serving as a reference for detecting an absolute position. Although detailed description of the position reset is omitted, the output of a reset sensor such as a photo interrupter is monitored, and position information is detected using a reset sensor output change as a trigger. This detected position information is used as a reference position for obtaining an absolute position. When the position reset is completed, proceed to the next step.

[Step 102]
Either one or both of temperature data and humidity data is detected using each sensor. The detected temperature data or humidity data is AD converted and loaded into the CPU.

[Step 103]
The number of times of lubrication is determined based on the acquired temperature data. The number of lubrication operations is determined using table data, for example. At this time, when the number of lubrication operations is determined using temperature data, the table data may be such that the number of lubrications is increased on the low temperature side and the number of lubrications is decreased on the high temperature side. In addition, when the number of lubrication operations is determined using humidity data, a data table may be used in which the number of lubrication operations is increased on the low humidity side and the number of lubrication operations is decreased on the high humidity side. Further, when the number of lubrication operations is determined from both the temperature data and the humidity data, the data having the larger number of table data is selected and used. FIG. 4 shows an example of the data table at that time.

[Step 104]
The coil is energized to generate thrust in the direction of the optical axis, and drive to either one is started. Here, it will be called a + direction.

[Step 105]
Position detection is performed using a position sensor to determine whether a predetermined position has been reached. If it has not reached, energization is continued and the moving unit is driven until it reaches. If it is determined that the predetermined position has been reached, the process proceeds to the next step.

  If the range for performing the lubrication operation is too narrow, there is a possibility that it may be necessary to drive in an unlubricated region during actual photographing. In the moving range of the taking lens, there is a margin on both sides of the moving range that is not used for actual shooting. That is, the lubrication operation range needs to perform the lubrication operation in a range that covers the moving range used in actual photographing. The above-mentioned predetermined position is the position of the movement area for this margin or the end position that is the movement limit (for example, the focus closest end).

[Step 106]
The coil is reversely energized and driven in the direction opposite to the driving direction of S104. Here, it will be referred to as “− direction”.
[Step 107]
Position detection is performed using a position sensor to determine whether a predetermined position has been reached. If it has not reached, energization is continued and the moving unit is driven until it reaches. If it is determined that the predetermined position has been reached, the process proceeds to the next step. The predetermined position is the other end position (for example, the focus infinite end) that becomes the other margin or the movement limit of the movement range described in S105. The operation from S104 to S107 becomes a lubrication operation, and the sliding oil applied to the contact portion between the bearing and the guide bar becomes evenly familiar.

[Step 108]
Increase the count of the counter that counts the number of lubrication operations (+1). Here, as shown in S104 to S107, the time when the moving unit reciprocates once in a predetermined section is counted as one lubrication operation.

[Step 109]
It is determined whether or not the lubrication operation has been performed only for the number of lubrications determined in S103. When the predetermined number of times has not been reached, the process returns to S104 again, and when the predetermined number of times has been reached, the lubricating operation is terminated.

  Thus, the lubrication operation of the linear actuator is completed, and the photographing operation can be started.

Cross-sectional view of optical equipment using linear actuator The block diagram which shows the video lens system of this invention Example The flowchart which shows operation | movement of the linear actuator of this invention Example. The figure which shows the example of a data table of this invention Example

Claims (6)

  An environmental condition detecting means for detecting an environmental condition in a linear actuator having a magnet and a drive coil for driving the moving part, and generating a thrust for driving the moving part by energizing the drive coil; A linear actuator comprising: a lubrication operation control unit that determines the number of lubrication operations for eliminating drive unevenness of the moving unit based on a detection result of the environmental condition detection unit.   2. The linear actuator according to claim 1, wherein the environmental condition detection means is temperature detection means for detecting temperature.   2. The linear actuator according to claim 1, wherein the environmental condition detection means is humidity detection means for detecting humidity.   2. The linear actuator according to claim 1, wherein the environmental condition detecting means is a temperature detecting means for detecting temperature and a humidity detecting means for detecting humidity.   In an optical apparatus having a photographic lens and a linear actuator for moving the photographic lens, the lens moves during photographing during a lubrication operation for eliminating drive unevenness of the moving unit including the photographing lens and a holding member for the photographing lens. An optical device characterized in that the lubricating operation is performed by moving in a moving range larger than the lens moving range.   6. The optical apparatus according to claim 5, further comprising a mechanical moving end for limiting a moving range of the moving unit, and moving to the moving end during the lubrication operation.

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