JP2008286751A - Actuator with position detection function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator with a position detection function, capable of connecting a position detection sensor and a controller, without getting anxious about attenuation of an output signal from the position detection sensor, and capable of contributing to miniaturization of the controller. <P>SOLUTION: The actuator uses a freely bendable flexible printed board as a signal cable for connecting the position detection sensor and the controller, the signal cable is constituted of a fixation-arranging part connected to an X-directional sensor part and fixed to the second member, and a movable marginal part consecutive adjacently to the fixation-arranging part, and extracted from the second member to be connected to the controller, and the fixation-arranging part of the signal cable is mounted with an A/D converter for converting an analog signal output by the X-directional sensor part into a digital signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an actuator that is used in, for example, various inspection devices, measuring devices, and conveying devices, and moves and positions an object freely in a predetermined direction, and more specifically, a movable member on which the object is mounted. The present invention relates to an actuator with a position detection function capable of detecting the amount of movement of the movable member and performing feedback control of the movable member with the amount of movement.

  Conventionally, as this kind of actuator with a position detection function, what is disclosed in WO2007 / 026673 is known. The actuator disclosed in this document is housed in a hollow spline shaft as a fixed member formed in a hollow shape, a spline nut as a movable member movable along the spline shaft, and the spline shaft. The spline nut comprises a magnet rod and a forcer coupled with the magnet rod and a forcer coupled with the spline nut. The spline nut is driven by inputting a drive current to the forcer and driving the linear motor. Can be freely advanced and retracted along the spline shaft.

  A linear scale is fixed along the longitudinal direction of the spline shaft, and a position detection sensor for reading the linear scale is mounted on the spline nut, and an output signal of the position detection sensor is referred to. However, the spline nut can be positioned at a predetermined position on the spline shaft by feedback controlling the drive current of the forcer.

  In the actuator configured as described above, the driving current of the forcer is generated by a controller provided separately from the actuator. The forcer and the position detection sensor are connected to a controller via a cable, and the controller compares the output signal of the position detection sensor input via the cable with the control content stored in advance and generates a drive current for the forcer. To do. This drive current is applied to the forcer via the signal cable.

Japanese Patent Application Laid-Open No. 2003-241838 shows the configuration of such a controller. The controller calculates the control amount of the actuator, the CPU that stores the control content of the actuator, the ROM that stores the control content of the actuator in advance, and reads the control content from this ROM and refers to the output signal of the position detection sensor. And a driver circuit that outputs a driving current corresponding to the control amount calculated by the CPU to a driving means such as a linear motor. Since the output signal of the position detection sensor is an analog signal, the driver circuit converts the digital signal into an A / D converter for passing it to the CPU, and converts the control signal output from the CPU into an analog signal. Also included in the controller is a D / A converter for passing to the controller.
WO2007 / 026673 JP 2003-241838 A

  In such an actuator with a position detection function, the position detection sensor is mounted on the actuator itself composed of a movable member and a fixed member, and is connected to the controller not mounted on the actuator by a signal cable. However, since the output signal of the position detection sensor is an analog signal, it is attenuated according to the length of the signal cable when transmitted to the controller via the signal cable, and noise is transmitted during transmission of the signal cable. The S / N ratio of the output signal of the position detection sensor input to the controller is likely to be lowered.

  For this reason, in a conventional actuator with a position detection function, the output signal of the position detection sensor taken out from the actuator is immediately amplified by an amplifier, and the amplified output signal is input to the A / D converter of the controller via a signal cable. Was taken. However, it is necessary to provide an amplifier separately from the controller, which leads to an increase in production cost, and it is necessary to provide an actuator and an amplifier as a set, resulting in restrictions on the installation location of the actuator. there were.

  The present invention has been made in view of such problems, and an object of the present invention is to connect the position detection sensor and the controller without worrying about attenuation of the output signal of the position detection sensor. An object of the present invention is to provide an actuator with a position detection function that can contribute to miniaturization of a controller.

  An actuator with a position detection function of the present invention that achieves the above object includes a first member on which a linear scale is disposed, a second member that is movable in the X direction with respect to the first member, and the second member. An X-direction motor unit that moves forward and backward with respect to the first member, and an analog that is mounted on the second member and faces a linear scale disposed on the first member, according to the amount of movement of the second member An X direction sensor unit for outputting a signal, a controller for sending a control current of the X direction motor unit based on an output signal of the X direction sensor unit, and a signal for inputting the output signal of the sensor unit to the controller A flexible printed circuit board (hereinafter referred to as “FPC”) is used as the signal cable. The signal cable is connected to the X direction sensor unit and fixed to the second member, and is connected to the controller by being drawn from the second member and continuing from the fixed member. An A / D converter that converts an analog signal output from the X direction sensor unit into a digital signal is mounted on the fixed arrangement portion of the signal cable.

  According to the actuator with a position detection function of the present invention configured as described above, the X-direction sensor unit mounted on the second member is connected to the controller by a signal cable formed from FPC. Since this FPC can be formed to be extremely thin and bendable, when this FPC is used for a signal cable, the second member and the controller can be connected without hindering the movement of the second member of the actuator.

  The signal cable made of FPC is composed of a fixed arrangement portion fixed to the second member and a movable margin portion drawn from the second member. Originally, the FPC is a resistor, a capacitor, or the like. It is used as a substrate for mounting electronic components, and it is possible to easily mount electronic components on the signal cable made of FPC. For this reason, if an A / D converter is mounted on the fixed arrangement portion of the signal cable, the analog signal output from the X direction sensor portion can be immediately converted into a digital signal. Can handle the output signal of the X direction sensor unit as a digital signal. Therefore, there is no need to worry about the attenuation of the output signal of the X direction sensor unit in the signal cable and the mixing of noise, and the position detection function can be highly accurate.

  Further, since the A / D converter is mounted on the signal cable made of FPC, the A / D converter can be omitted from the controller, and the controller can be miniaturized.

  The present invention can be applied to an actuator composed of a relatively movable first member and a second member. For example, a relatively movable first member, a second member, and a second member such as an XY table actuator can be used. The present invention can also be applied to an actuator composed of three members. In this case, in addition to providing an X direction sensor unit that outputs an analog signal corresponding to the amount of movement of the second member relative to the first member, Y outputs an analog signal corresponding to the amount of movement of the third member relative to the second member in the Y direction. A direction sensor unit can be provided, and the output signals of these two sensor units can be input to the controller. Further, the signal cable for inputting the output signal controller of the X direction sensor unit and the signal cable for inputting the output signal of the Y direction sensor unit to the controller can share one FPC. Thereby, the number of signal cables drawn out from the XY table actuator can be reduced, and the handling of the actuator can be facilitated.

  Hereinafter, an actuator with a position detection function of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing an embodiment of an XY table actuator to which the present invention is applied. The XY table actuator 1 includes a fixed plate 2 fixed to a fixed part such as a housing or a bed of a mechanical device, an intermediate plate 4 assembled to the fixed plate 2 via a linear guide, and a linear guide. And a movable plate 5 assembled to the intermediate plate 4.

  The intermediate plate 4 is provided so as to be movable in the X direction with respect to the fixed plate 2, and the movable plate 5 is movable in the Y direction with respect to the intermediate plate 3. Therefore, by fixing a movable body such as an inspection stage and a transfer table to the movable plate 5, the movable body can be freely moved in the X direction and the Y direction with respect to the fixed plate 2. ing. That is, in this XY table actuator, the fixed plate 2 corresponds to the first member of the present invention, the intermediate plate 4 corresponds to the second member, and the movable plate 5 corresponds to the third member.

  The fixed plate 2, the intermediate plate 4 and the movable plate 5 have the same size in the XY plane. As shown in FIG. 1, when the intermediate plate 4 and the movable plate 5 are set to the home position, Three plates 2, 4 and 5 overlap each other to form a rectangular body. Therefore, the XY table actuator 1 itself is very compact.

  Further, although it cannot be grasped from the appearance shown in FIG. 1, an X-direction motor portion that drives the intermediate plate 4 in the X direction is provided between the fixed plate 2 and the intermediate plate 4, while the intermediate plate 4 A Y-direction motor unit for driving the movable plate 5 in the Y direction is accommodated between the movable plate 5 and the movable plate 5. These X direction motor unit and Y direction motor unit are connected to a controller 9 by a driving power cable 8, and the controller 9 sends drive current to the X direction motor unit and the Y direction motor unit. The specific configuration of the X direction motor unit and the Y direction motor unit will be described in detail later.

  The XY table actuator 1 includes two sets of position detection means for measuring the amount of movement of the intermediate plate 4 in the X direction relative to the fixed plate 2 and the amount of movement of the movable plate 5 in the Y direction relative to the intermediate plate 4. Each position detection means is composed of a linear scale and a position detection sensor for reading the linear scale. The position detection sensor is mounted on the intermediate plate 4, while the linear scale is at a position facing the position detection sensor. It is held by the fixed plate 2 or the movable plate 5. The combination of the linear scale and the position detection sensor may be an optical reading method or a magnetic reading method.

  Then, the output signals of the two position detection sensors are input to the controller 9 via the sensor signal cable 10, and the controller 9 refers to the output signals of the detection sensors and the X direction motor unit and the Y direction motor unit. A drive current is generated.

  FIG. 2 is a perspective view showing the fixed plate 2. The fixing plate 2 has a receiving groove 20 in the center and is formed in a channel shape, and a ball rolling groove 30 is formed on the inner surface facing the receiving groove 20. The movable plate 5 is also formed in the same shape as the fixed plate 2, but the phases when superimposed on the intermediate plate 4 are shifted from each other by 90 degrees. That is, in the fixed plate 2, the accommodation groove 20 is formed along the X direction, but in the movable plate 5, the accommodation groove 20 is formed along the Y direction.

  The intermediate plate 4 is formed in a flat plate shape having the same size as the fixed plate 2 and the movable plate 5, and the intermediate plate 4 indicated by a one-dot chain line is overlapped with the fixed plate 2 as shown in FIG. Thus, a space corresponding to the size of the accommodation groove 20 is formed between the fixed plate 2 and the intermediate plate 4, and this space is used as the accommodation chamber 60 of the X-direction motor unit 6 described above. It has become. Such a space is also formed between the movable plate 5 and the intermediate plate 4, and this space is used as the accommodation chamber 70 of the Y-direction motor unit described above.

  FIG. 3 is a perspective view of the XY table actuator 1 showing a state where the movable plate 5 is removed. A pair of linear guides 21 are fixed to the surface of the intermediate plate 4 facing the movable plate at an interval in the X direction. Each linear guide 21 is provided with a load rolling groove 22 facing the rolling groove 30 of the ball formed on the movable plate 5, and the rolling groove 30 of the movable plate 5 and the load rolling groove 22 of the linear guide 21. The movable plate 5 can be freely moved in the Y direction with respect to the intermediate plate 4 by rolling a plurality of balls while applying a load therebetween. Further, the linear guide 21 is provided with an infinite circulation path of the ball, and the movable plate 5 can move with respect to the intermediate plate 4 within a range in which its rolling groove 30 faces the linear guide 21. ing.

  Further, a Y-direction motor unit 7 is disposed on the intermediate plate 4 so as to be sandwiched between the pair of linear guides described above. The Y-direction motor unit 7 is a synchronous linear motor, and is fixed to the movable plate 5 and a small number of stator magnets 71 arranged on the intermediate plate 4 in a line. It is comprised from the coil member 72 which opposes through a clearance gap.

  The stator magnet 71 is arranged so that the N pole and the S pole are alternately directed to the coil member 72. These stator magnets 71 are arranged on a synthetic resin holding plate 73. By fixing the holding plate 73 to the intermediate plate 4, the stator magnet 71 can be easily arranged on the intermediate plate 4. To get. The stator magnets 71 are arranged on the holding plate 73 by bonding. However, the stator magnet 71 can be integrated with the holding plate 73 by injection molding the holding plate 73.

  The coil member 72 is formed by winding a coil around a core member made of a ferromagnetic material such as iron, and the tip of the core member is interposed between the stator magnet 71 and a slight gap. Opposite. The coil is composed of three phases, u-phase, v-phase, and w-phase. When a three-phase alternating current is passed through these coils, the coil member 71 generates a moving magnetic field along the Y direction. Based on this moving magnetic field, a magnetic attractive force or a magnetic repulsive force acts between the stator magnet 71 and the coil member 72 so that the coil member 72 can be propelled along the arrangement direction of the stator magnet 71. It has become.

  3 shows the structure of the surface side of the intermediate plate 4, that is, the side facing the movable plate 5, but a pair of linear guides are also provided on the back surface side of the intermediate plate 4, that is, the side facing the fixed plate 2. 21 is arranged so that the intermediate plate 4 can move freely in the X direction with respect to the fixed plate 2. Further, the X direction motor unit that drives the intermediate plate 4 in the X direction with respect to the fixed plate 2 is composed of a stator magnet and a coil member as in the case of the Y direction motor unit 7. Coil members are fixed to the fixing plate 2 on the back side.

  Further, in FIG. 3, reference numeral 74 denotes a partition wall that faces the receiving groove 20 of the movable plate 5 with a slight gap, and is provided at both ends in the Y direction on the surface side of the intermediate plate 4. The partition wall 74 prevents dust from entering the storage chamber 70 of the Y-direction motor unit 7 formed between the movable plate 5 and the intermediate plate 4 from the outside, and is a coil fixed to the movable plate 5. The movement range of the member 72 is limited. That is, the movable plate 5 can make a stroke within the moving range of the coil member 72 restricted by the pair of partition walls 74.

  Similarly, a pair of partition walls 75 are respectively provided on the back surface side of the intermediate plate 4 corresponding to both ends in the X direction, and the X direction motor portion accommodating chamber formed between the fixed plate 2 and the intermediate plate 4. In addition to preventing dust from entering 60 from the outside, the moving range of the coil member fixed to the fixed plate 2 is limited.

  On the other hand, as shown in FIG. 1 or FIG. 3, one end of the driving power cable 8 is connected to the coil member 72 fixed to the movable plate 5, and the other end of the driving power cable 8 is the XY table. It is connected to a controller 9 provided separately from the actuator 1. The driving power cable 8 is formed of a flat belt-like FPC having a thickness of about 150 μm, and is mounted on the movable plate 5 while allowing the movement of the movable plate 5 in the X direction and the Y direction by bending flexibly. The coil member 72 of the Y drive motor 7 thus connected is connected to the controller 9.

  FIG. 4 is a perspective view showing the sensor signal cable 10. This sensor signal cable is also formed of a flat belt-like FPC and is fixed to the intermediate plate 4. Then, the X-direction sensor unit 11 and the Y-direction sensor unit 12 as position detection sensors fixed to the intermediate plate 4 are allowed to move in the X direction while allowing the intermediate plate 4 to move in the X direction by bending flexibly. Connected.

  The sensor signal cable 10 is connected to the X-direction sensor unit 11 and the Y-direction sensor unit 12 and is fixed to the intermediate plate 4 and is continuous from the fixed installation unit 13. The movable margin portion 14 is drawn from the intermediate plate 4 and connected to the controller 9. The movable margin portion 14 is freely curved to allow the intermediate plate 4 to move in the X direction. Can be done. The fixed arrangement portion 13 is branched into two systems from the middle. The X direction sensor portion 11 is connected to one end 13a, and the Y direction sensor portion 12 is connected to the other end 13b.

  FIG. 5 is a perspective view showing a state in which the sensor signal cable 10 is disposed on the intermediate plate 4, and the Y drive means 7 disposed on the surface of the intermediate plate 4 so that the sensor signal cable can be easily seen. The state where the stator magnet 71 and its holding plate 73, one linear guide 21, and the partition wall 74 are removed is shown. As can be seen from this figure, the intermediate plate 4 is formed with a recess 40 for fixing the X direction sensor unit 11 and the Y direction sensor unit 12, and the X direction sensor unit 11 and the Y direction sensor unit. 12 is fixed in the recess 40 and faces the linear scale. The linear scale 15 facing the X direction sensor unit 11 is disposed on the fixed plate along the X direction. Moreover, the linear scale which the Y direction sensor part 12 opposes is arrange | positioned by the movable plate 5 along the Y direction, and is not drawn in FIG.

  When the intermediate plate 4 or the movable plate 5 moves back and forth, the X direction sensor unit 11 and the Y direction sensor unit 12 output analog signals having a waveform corresponding to the movement amount and movement speed. Conventionally, this analog signal is taken out of the XY table actuator 1 by the sensor signal cable 10, amplified by an amplifier, and converted into a digital signal by an A / D converter of the controller. However, if the analog signal is taken out of the XY table actuator 1 as it is, the attenuation of the signal and the superimposition of noise will be a problem. There was a problem that it was difficult to detect.

  Therefore, in the XY table actuator 1, a flexible FPC is adopted as the sensor signal cable 10 for connecting the X direction sensor unit 11 or the Y direction sensor unit 12 to the controller 9, and the original function of the circuit board of the FPC is used. Then, electronic components such as resistors and capacitors were mounted on the surface, and the functions of an amplifier and an A / D converter were mounted on the sensor signal cable 10 itself. Specifically, as shown in FIG. 4, the electronic component 16 that becomes a circuit of an amplifier and an A / D converter is mounted on the fixed arrangement portions 13a and 13b of the sensor signal cable 10, and the X-direction sensor portion 11 or the Y-direction sensor portion 11 or Y The analog signal output from the direction sensor unit 12 is immediately converted into a digital signal on the sensor signal cable 10, and the digital signal is output to the controller 9 through the movable margin 14 of the sensor signal cable 10.

  FIG. 6 is a block diagram showing a control system for performing feedback control of the X direction motor unit and the Y direction motor unit 7. The X direction sensor unit 11 and the Y direction sensor unit 12 mounted on the XY table actuator 1 are connected to the controller by a sensor signal cable 10 formed of FPC. An amplifier and an A / D converter are mounted on the sensor signal cable. On the other hand, the controller 9 includes a ROM in which control contents such as a drive sequence of the XY table actuator are stored in advance, and the X direction motor based on the stored contents of the ROM and output signals of the X direction sensor unit and the Y direction sensor unit. CPU for calculating the control amount of the motor unit and the Y direction motor unit, a D / A converter for converting a digital signal as a control amount calculated by the CPU into an analog signal, and the X direction from the control amount converted to the analog signal And a driver circuit that generates a drive control current for the motor unit and the Y-direction motor unit. The drive control current generated by the driver circuit is transmitted to the coil member 72 of the X-direction motor unit or the Y-direction motor unit 7 by the driving power cable 8.

  According to such a configuration of the control system, the amplifier that amplifies the analog signal output from the X direction sensor unit 11 or the Y direction sensor unit 12 and the A / D converter that converts the analog signal into a digital signal are used for the sensor. The amplifier and the A / D converter are mounted on the signal cable 10 and are provided in the vicinity of the X direction sensor unit 11 or the Y direction sensor unit 12 inside the XY table actuator 1. Therefore, the output signals of the X direction sensor unit 11 and the Y direction sensor unit 12 can be transmitted to the controller 9 accurately. As a result, it is possible to increase the accuracy of control of the X-direction motor unit and the Y-direction motor unit 7.

  Since the FPC used as the sensor signal cable 10 is essentially a board used for mounting electronic components, an amplifier and an A / D converter can be mounted on the sensor signal cable 10 without any problem. Is possible. By mounting the amplifier and the A / D converter on the sensor signal cable 10, the size of the circuit board stored in the controller 9 can be reduced, and the controller 9 can be downsized.

  Further, since the output signal of the X direction sensor unit 11 or the Y direction sensor unit 12 is converted into a digital signal in the XY table actuator 1, a sensor signal cable 10 from the XY table actuator 1 to the controller 9 is provided. Even if it is long, there is no need to worry about attenuation of the output signal of each sensor unit and mixing of noise, and it becomes possible to increase the degree of freedom of the arrangement position of the controller with respect to the XY table actuator.

  In the above description, an amplifier is inserted before the A / D converter, but the output signal of the X direction sensor unit 11 or the Y direction sensor unit 12 is converted from an analog signal to a digital signal immediately after these sensor units 11 and 12. Therefore, when there is a sufficient amplitude in the output signals of the sensor units 11 and 12, it is not necessary to provide the amplifier.

  In the above description, the XY table actuator is applied to the present invention. However, the present invention can also be applied to a uniaxial actuator in which the second member moves only in the X direction with respect to the first member. is there.

It is a perspective view which shows embodiment of the XY table actuator to which this invention is applied. It is a perspective view which shows the fixing plate of the XY table actuator which concerns on embodiment. It is a perspective view which shows the state which removed the movable plate from the XY table actuator which concerns on embodiment. It is a perspective view which shows the signal cable for sensors which connects a controller, an X direction sensor part, and a Y direction sensor part. It is a perspective view which shows the signal cable for sensors arrange | positioned on the intermediate | middle plate. It is a block diagram which shows the feedback control system of a X direction motor part and a Y direction motor part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... XY table actuator, 2 ... Fixed plate, 4 ... Intermediate plate, 5 ... Movable plate, 7 ... Y drive means, 9 ... Controller, 10 ... Signal cable for sensors, 11 ... X direction sensor part, 12 ... Y direction sensor Part, 13a, 13b ... fixed arrangement part, 14 ... movable margin part

Claims (3)

A first member on which a linear scale is disposed, a second member movable in the X direction with respect to the first member, an X-direction motor section for moving the second member forward and backward with respect to the first member, An X direction sensor unit that is mounted on the second member and faces a linear scale disposed on the first member and outputs an analog signal corresponding to the amount of movement of the second member, and an output of the sensor unit In an actuator with a position detection function configured by a controller that sends a control current of the X-direction motor unit based on a signal, and a signal cable for inputting an output signal of the sensor unit to the controller,
The signal cable is made of a flexible printed circuit board that can be bent,
The signal cable is connected to the sensor unit and is fixed to the second member. The signal cable is continuous from the fixed member and is drawn from the second member and connected to the controller. It consists of a movable direction margin part,
An actuator with a position detection function, wherein an A / D converter for converting an analog signal output from the sensor unit into a digital signal is mounted on the fixed arrangement portion of the signal cable. 2. The actuator with a position detection function according to claim 1, wherein an amplifier circuit for amplifying an analog signal output from the sensor unit is mounted on the fixed arrangement portion of the signal cable. A third member which is provided with a linear scale and is movable in the Y direction with respect to the second member, a Y-direction motor unit for moving the third member forward and backward with respect to the second member, and the second member And a Y-direction sensor unit that is opposed to a linear scale disposed on the third member and outputs an analog signal corresponding to the amount of movement of the third member. The Y-direction sensor is an X-direction sensor. 2. The actuator with a position detecting function according to claim 1, wherein the signal cable is shared.

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