JP2009077104A - Coil drive circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coil drive circuit which accelerstes the on/off-switching speed of a switching element and is reduced in size for reducing the cost. <P>SOLUTION: A JK flip flop UI outputs a pulse signal, synchronized with a clock CLK on the basis of ON/OFF signal, and the pulse signal is inputted to the primary-side coil of a pulse transformer L1. A diode bridge 11 rectifies the output from the secondary-side coil of the pulse transformer L1 and outputs a drive current resulting from rectifying the pulse signal, to the gates of MOS-FETs Q1 and Q2. The MOS-FETs Q1 and Q2 perform switching operations, according to the output voltages for turning on/off the current flowing to a coil of a linear motor. The present invention is applicable to motor excitation switching circuits, used in drive devices of motors for use in the stage of a semiconductor exposure devices. or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coil drive circuit, and more particularly to a coil drive circuit that can switch on / off of a switching element at high speed.

  A three-phase linear motor is used for driving a mask stage and a wafer stage in a semiconductor exposure apparatus. In a three-phase linear motor with a long moving stroke, in a MM (moving magnet) type linear motor in which the stator is a coil and the mover is a magnet, the coil of the part where the magnet of the mover does not exist is not energized and moved. A so-called excitation switching type linear motor that sequentially switches the coil to be energized according to the position where the child moves is used for power saving.

The present applicant has previously proposed Patent Document 1 and Patent Document 2 using a photocoupler as a motor excitation switching circuit for sequentially switching the energized coils.
JP 2002-124862 A JP 2002-142490 A

  However, as in the past, MOS-FETs (insulated gate bipolar transistors) and IGBTs (insulated gate bipolar transistors) are used to drive the output side of the photocoupler with a photovolt output that uses the electromotive force of the photodiode as an output. In this case, there is a problem that it is difficult to switch on / off at a relatively high speed under the influence of the input capacitance due to the MOS-FET or IGBT.

  For this reason, gate drive couplers that drive the gates of MOS-FETs and IGBTs have been used. In this case, a separate primary side is provided for each MOS-FET or IGBT corresponding to each coil to be switched. It was necessary to supply power with a DC-DC converter that was isolated from the power supply, which hindered miniaturization of the circuit for switching excitation and also prevented cost reduction.

  The present invention has been made in view of such problems, and is intended to increase the switching speed of switching elements at high speed and reduce the size to reduce the cost.

  A coil drive circuit according to the present invention includes a pulse signal generation unit that generates a predetermined pulse signal in a coil drive circuit that drives a coil by causing a current to flow through a predetermined coil among a plurality of coils constituting a linear motor. A signal transmission means for transmitting the generated pulse signal, a rectifying element for rectifying the transmitted pulse signal, and a switching operation according to the level of the driving voltage obtained by rectifying the pulse signal to flow through the coil A first switching element for turning on / off the current, and the signal transmission means connects the pulse signal generating means and the rectifying element in an electrically insulated state, and the pulse signal is transferred from the pulse signal generating means to the rectifying element. It is characterized by transmitting.

  According to the present invention, on / off switching of a switching element can be performed at high speed, and the size can be reduced to reduce cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram showing a configuration example of a coil drive circuit to which the present invention is applied.

  The coil drive circuit is a motor excitation switching circuit disposed between a motor drive circuit that drives a linear motor and a coil of the linear motor, and is used, for example, as a motor drive device used for a stage of a semiconductor exposure apparatus. Used.

  The coil drive circuit is JK flip-flop U1, pulse transformer L1, diode bridge 11, LPF (low pass filter) 12, discharge resistor R1, gate resistor 13, MOS-FETQ1, MOS-FETQ2, surge absorber D5, photocoupler PC1 , And a resistor R4.

  The JK flip-flop U1 has two inputs J and K, a clock CLK, and two outputs Q and / Q (Q inversion). In the JK flip-flop U1, the drive power supply VCC is connected to the two inputs J and K, and both ends of the primary coil of the pulse transformer L1 are connected to the two outputs Q and / Q. ON / OFF signal in JK flip-flop U1 (/ PRE in the figure indicates that it is forcibly turned on regardless of clock CLK, and / CLR indicates that it is forcibly turned off regardless of clock CLK) When is low, no pulse signal synchronized with the clock CLK is output. On the other hand, when the ON / OFF signal is high, the pulse signal synchronized with the clock CLK is primary coil of the pulse transformer L1. Is output.

  A waveform shaping circuit consisting of capacitors and resistors is provided between the JK flip-flop U1 and the end of the primary coil of the pulse transformer L1, and after shaping the waveform of the pulse signal, the primary of the pulse transformer L1 You may make it output to a side coil.

  The pulse transformer L1 is a pulse transformer for signal transmission that transmits a pulse signal. The pulse transformer L1 connects the JK flip-flop U1 and the diode bridge 11 in an electrically insulated state, and converts the pulse signal from the JK flip-flop U1 into a diode bridge. 11 is transmitted. Both ends of the secondary coil of the pulse transformer L1 are connected to the diode bridge 11.

  The diode bridge 11 includes four rectifier elements D1 to D4 connected in a bridge shape, and full-wave rectifies the output from the pulse transformer L1. Note that the method of rectifying the output from the pulse transformer L1 is not limited to full-wave rectification. For example, another rectification method such as half-wave rectification of the output from the pulse transformer L1 by one rectifying element may be used. Good.

  One of the output ends of the diode bridge 11 is connected to the gate of the MOS-FET Q1 via the gate resistor R2 and the gate of the MOS-FET Q2 via the gate resistor R3, and the other is connected to the source of the MOS-FET Q1 and the MOS-FET Q2 Connected to the connection end with the source. In addition, at two output ends of the diode bridge 11, a discharge resistor R1 for discharging the charge stored in the LPF 12 composed of the capacitor C1 and the input capacitances (parasitic capacitances) of the MOS-FET Q1 and the MOS-FET Q2 is provided. Is connected.

  That is, in the coil drive circuit, when a pulse signal is output from the JK flip-flop U1, the pulse signal is transmitted to the diode bridge 11 by the pulse transformer L1. Subsequently, the pulse signal is rectified by the diode bridge 11 and approximately DC voltage (drive voltage) obtained by rectification is applied to the gate resistor R2 and the gate resistor R3 by the LPF 12, respectively.

  The MOS-FET Q1 and the MOS-FET Q2 perform a switching operation according to the drive voltage supplied to the gates. That is, when the level of the drive voltage input to the gate of the MOS-FET Q1 changes from the low level to the high level and exceeds a predetermined threshold voltage, the state of the MOS-FET Q1 is turned on. On the other hand, when the level of the drive voltage input to the gate of the MOS-FET Q1 changes from the High level to the Low level and falls below a predetermined threshold voltage, the state of the MOS-FET Q1 is turned off. MOS-FETQ2 is the same as MOS-FETQ1.

  Therefore, when the drive voltage is applied to the gate resistor R2 and the gate resistor R3, the gates of the MOS-FET Q1 and the MOS-FET Q2 are driven, the MOS-FET Q1 and the MOS-FET Q2 are turned on, and the drive current is supplied to the linear motor. It becomes possible to flow through the coil.

  On the other hand, if no pulse signal is output from the JK flip-flop U1, the MOS-FET Q1 and the MOS-FET Q2 are turned off, and no drive current flows through the coil of the linear motor. Further, when the MOS-FET Q1 and the MOS-FET Q2 are turned off, the charges stored in the parasitic capacitances of the MOS-FET Q1 and the MOS-FET Q2 are discharged through the discharge resistor R1.

  Surge absorber D5 has a terminal voltage of MOS-FETQ1 and MOS-FETQ2 that exceeds a certain level when a counter electromotive voltage is generated by the linear motor coil connected between OUT + and OUT- in the figure. It functions as a bi-directional surge absorber that clamps against rising.

  As disclosed in the above-mentioned Patent Document 1 previously proposed by the present applicant, the photocoupler PC1 is configured such that when the MOS-FET Q1 and the MOS-FET Q2 are turned off, the MOS-FET Q1 and the MOS-FET Q1 It is provided to discharge the charge of the FETQ2 and accelerate the turn-off, and is connected in parallel with the discharging resistor R1. The photocoupler PC1 includes, for example, a diode as a light emitting element and a phototransistor as a light receiving element.

  That is, when the MOS-FET Q1 and the MOS-FET Q2 are turned off without outputting a pulse signal from the JK flip-flop U1, the photocoupler PC1 is turned on, and the MOS-FETQ1 is passed through the phototransistor of the photocoupler PC1. And the charge stored in the parasitic capacitance of MOS-FETQ2 is discharged. Thereby, the switching time for turning off the MOS-FET Q1 and the MOS-FET Q2 can be greatly shortened.

  As described above, in the present embodiment, the coil drive circuit is insulated from the primary side circuit, and instead of driving a MOS-FET using a conventional photocoupler, a pulse transformer is used. A pulse signal generated from a constant clock is input to the pulse transformer, and the gate of the MOS-FET is driven by the output voltage of the rectified pulse transformer.

  That is, normally, a pulse transformer cannot be used for transmission of a DC voltage or a low-frequency signal or power due to the influence of waveform distortion or the like, but in this embodiment, a bridge type is used for the output of the pulse transformer. By rectifying with the diode connected to the, it is possible to generate a potential to be turned on at the gate input of the MOS-FET while the pulse waveform is input to the input of the pulse transformer. On the other hand, when the pulse waveform is stopped, the potential of the gate input of the MOS-FET is lowered, and the MOS-FET is turned off.

  Compared to the photovoltaic output of a photocoupler that has been used in the past, the signal transmission by a pulse transformer can supply voltage to the MOS-FET without delay, and a separate DC-DC power supply or the like can be supplied to each MOS-FET. There is no need to provide a MOS-FET with only passive devices. As a result, the switching element can be switched on and off at high speed, and a small and low-cost coil drive circuit can be configured.

  Also, conventionally, a gate drive coupler and a DC-DC converter are used to insulate the primary drive power supply VCC from the motor drive system, and the gate drive coupler diode is based on the ON / OFF signal. The MOS-FET was turned on by passing current, but when this configuration is adopted, the devices used for each MOS-FET are gate drive couplers and DC-DC converters. Although the number can be reduced, there is a limit to downsizing and cost reduction because it is relatively expensive and requires a mounting area on the substrate.

  On the other hand, in this embodiment, the number of elements is larger than in the conventional case, but mainly because there are many passive devices, the area on the mounting surface is small, and the cost is advantageous. Can be expected. In addition, compared to the case of the photovol output disclosed in the above-mentioned Patent Document 1, Patent Document 2, etc., the ability to supply a voltage to the gate of the MOS-FET is high, so that it can be turned on at high speed. .

  In addition, when a photocoupler or gate driver is used as in the past, each channel consumes a current of several mA to 10 mA. On the other hand, in the system using the pulse transformer as in the present embodiment, there is basically no portion that consumes power, so that the power supply and the power holding portion can be downsized. .

  As described above, according to the present invention, since a photovol output photocoupler is not used as in the prior art, it can be turned on at high speed when the MOS-FET is turned on. In addition, since it is not necessary to use a gate driver or a DC-DC converter for each MOS-FET, a coil drive circuit with a small mounting area can be configured at low cost.

  In this embodiment, in order to simplify the description, the description has been given by taking MOS-FET Q1 and MOS-FET Q2 as one set of MOS-FETs, but the number of MOS-FETs and the number of sets are arbitrary. It's okay. Further, instead of the MOS-FET, other switching elements such as IGBT may be used.

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

It is a circuit diagram which shows the structural example of the coil drive circuit to which this invention is applied.

Explanation of symbols

  11 diode bridge, 12 LPF, 13 gate resistance, C1 capacitor, D1 to D4 diode, D5 surge absorber, L1 pulse transformer, PC1 photocoupler, Q1 MOS-FET, Q2 MOS-FET, R1 discharge resistance, R2 gate resistance, R3 gate resistor, R4 resistor, U1 JK flip-flop, VCC drive power supply

Claims (4)

In a coil drive circuit that drives a coil by passing a current through a predetermined coil among a plurality of coils constituting the linear motor,
Pulse signal generating means for generating a predetermined pulse signal;
Signal transmission means for transmitting the generated pulse signal;
A rectifying element for rectifying the transmitted pulse signal;
A first switching element that performs a switching operation according to a level of a driving voltage obtained by rectifying the pulse signal, and turns on / off a current flowing through the coil;
The signal transmission means connects the pulse signal generation means and the rectifier element in an electrically insulated state, and transmits the pulse signal from the pulse signal generation means to the rectifier element. circuit. The signal transmission means is a pulse transformer having a primary side coil to which the pulse signal is input and a secondary side coil for transmitting the pulse signal input to the primary coil.
The coil drive circuit according to claim 1, wherein the rectifier element rectifies an output from the secondary coil. The coil drive circuit according to claim 1, further comprising a discharging resistor for discharging the charge stored in the parasitic capacitance of the first switching element. A second switching element provided in parallel with the discharging resistor;
The coil driving circuit according to claim 3, wherein the second switching element is turned on when the first switching element is turned off to discharge the electric charge.

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