JP4084866B2 - Degaussing power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a demagnetizing power supply device that supplies direct current to an exciting coil or the like of an electromagnetic chuck by alternately switching energization directions.
[0002]
[Prior art]
As one of this type of demagnetizing power supply device, there is a device that demagnetizes an electromagnetic chuck and a workpiece by supplying a damping alternating current having a predetermined voltage to an exciting coil (see Japanese Patent Publication No. 61-19095).
[0003]
This conventional apparatus rectifies alternating current to direct current, and in the switching circuit, the polarity (that is, the energization direction) is alternately switched in the switching circuit, and the energization time (switching period) to the exciting coil is gradually reduced, thereby Attenuating alternating current is generated.
[0004]
The decaying alternating current is performed using a so-called demagnetization pattern that gradually reduces the energization time to the exciting coil. The demagnetization pattern is composed of an arrangement of times for gradually decreasing the energization time, and is created based on a time that is an integral multiple of the period T of a constant frequency pulse signal generated from a clock pulse generator in the demagnetization power supply apparatus.
[0005]
However, in the conventional apparatus, the period T of the pulse signal that is the basis for creating the demagnetization pattern does not coincide with the period of the alternating current to be rectified and does not coincide with the period t of the alternating current component in the rectified direct current. The energization time to the coil is not an integral multiple of the AC component period t, and the polarity switching (energization direction switching) timing is not synchronized with the AC component period.
[0006]
As a result, in the conventional apparatus, even if the energization time is the same, it is unavoidable that the output voltage of the switching circuit varies, and the current flowing in the exciting coil varies. In particular, since such a variation has a large influence in the case of a short energization time, a large influence is generated at the final stage of the demagnetization pattern, and a large variation occurs in the demagnetization effect.
[0007]
In addition, in the conventional apparatus, the optimum demagnetization pattern can be selected depending on the shape, material, size, etc. of the workpiece that is the demagnetization object. Each time a change is made, a new degaussing pattern must be created and added to the memory, resulting in a very large memory capacity for the degaussing pattern.
[0008]
[Problems to be solved]
From the above, it is desirable to set each energization time to a cycle that is an integral multiple of the cycle of the AC component in the rectified DC, and to synchronize the switching timing with the cycle of such AC component.
[0009]
It is also desirable to reduce the memory capacity by enabling the degaussing operation by one degaussing pattern to be executed from the middle of the degaussing pattern without starting from the beginning of the degaussing pattern.
[0010]
[Solution, action and effect]
The demagnetizing power supply device of the present invention includes a period detection circuit that detects a period of alternating current supplied to a rectifier circuit that converts alternating current into direct current and generates a pulse signal corresponding to the period, and a direction of energization to the excitation coil. A memory circuit storing at least one demagnetization pattern including a plurality of operation designation signals to be designated and a plurality of time designation signals for designating energization periods to the excitation coil, and a control signal synchronized with an AC cycle inputted to the rectifier circuit And a processing circuit for outputting to the switching circuit for switching the exciting current that supplies the exciting coil to the exciting coil.
[0011]
The processing circuit designates a predetermined address in the memory circuit, causes the signal in the address to be output from the memory circuit, counts the pulse signals output from the period detection circuit, and obtains the number of pulse signals from the memory circuit. Each time it matches the value corresponding to the specified signal, the address specified in the memory circuit is changed, and a control signal is output based on the output operation specifying signal and pulse signal.
[0012]
The processing circuit outputs a signal within a predetermined address from the memory circuit and designates it as the memory circuit each time the number of pulse signals output from the period detection circuit matches the value corresponding to the time designation signal obtained from the memory circuit. Each time the address to be changed is changed and the number of output pulse signals of the period detection circuit matches the value corresponding to the time designation signal from the memory circuit, the original state is restored. Thereby, the operation designation signal and the time designation signal are sequentially output from the memory circuit.
[0013]
The processing circuit also outputs a control signal synchronized with the AC cycle before rectification to the switching circuit based on the operation designation signal output from the memory circuit and the pulse signal output from the cycle detection circuit. Such a control signal can be generated by an AND condition between the operation designation signal and the pulse signal. Thus, the switching circuit switches the polarity of the rectified direct current alternately and supplies it to the exciting coil. The degaussing operation ends when the operation of the degaussing pattern starting from a predetermined address is completed.
[0014]
As described above, a pulse signal synchronized with the AC cycle before rectification is generated from the cycle detection circuit, and specified to the memory circuit each time the number of generated pulse signals matches the time specification signal obtained from the memory circuit. If the address is changed, each energization time to the excitation coil by the switching circuit is a cycle that is an integral multiple of the cycle of the AC component in the rectified DC, and the timing of switching the energization direction is the cycle of such an AC component. Synchronize with
[0015]
The processing circuit outputs an address signal for designating an address storing a signal to be output to the memory circuit, and receives the time designation signal and the pulse signal, counts the received pulse signal, Counting means for outputting an address change signal for changing the address signal output from the addressing means to the next address signal according to the demagnetization pattern each time the count value reaches a value corresponding to the received time designation signal, and operation designation Output synchronization means for outputting the control signal based on the signal and the pulse signal can be included. The counting means is returned to the original state every time the number of output pulse signals of the cycle detection circuit matches the value corresponding to the time designation signal from the memory circuit.
[0016]
The power supply device further includes an initial address setter that selectively sets an initial address of a demagnetization pattern to be used, and the processing circuit designates the initial address set in the initial address setting means in the memory circuit, and then a pulse signal The address designated for the memory circuit can be changed each time the number matches the value corresponding to the time designation signal obtained from the memory circuit.
[0017]
When the initial address setter is used, the processing circuit uses the initial address set in the initial address setter as the start address out of the demagnetization pattern including the initial address set in the initial address setter in the middle, and the start address The degaussing operation can be executed from the beginning. In this way, an arbitrary term (e.g., item i) in the middle depending on the material and size of the demagnetization object without executing the degaussing operation from the beginning (the first item) of one demagnetization pattern. Since one degaussing pattern stored in the memory can be used in common for a plurality of types of degaussing, the number of degaussing patterns stored in the memory circuit can be reduced. It is possible to demagnetize various types of demagnetization objects having different sizes and the like.
[0018]
However, the processing circuit may execute a degaussing operation from the beginning of the degaussing pattern for the degaussing pattern using the address set as the initial address as the start address. In this case, it is preferable that a plurality of demagnetization patterns corresponding to the material and size of the workpiece to be demagnetized are stored in the memory circuit, and the initial address setter is used for selecting a desired demagnetization pattern.
[0019]
The power supply device further includes a switching number setting device for setting the number of times of switching in the energization direction, and the processing circuit further counts the number of energizations to the exciting coil based on the control signal or the operation designation signal, and the count value is A second counting means for generating an operation stop signal for stopping the operation of the processing circuit when the value set in the switching number setting device is reached may be included. In this way, the number of times of switching the energization direction can be set according to the material and size of the object to be demagnetized, and since it can be executed in the middle of one demagnetization pattern, it is stored in the memory. One degaussing pattern can be used in common for multiple types of degaussing. As a result, even if the number of degaussing patterns stored in the memory circuit is small, many types of degaussing objects with different materials and sizes can be used. Can be demagnetized.
[0020]
The counting means receives the time designation signal and the pulse signal, counts the received pulse signal, and outputs a carry signal every time the count value reaches a value corresponding to the received time designation signal; and the counting means The address change signal generating means for changing the address designation signal output from the address designation means to the next address designation signal according to the demagnetization pattern and outputting the address change signal for clearing the count value of the count means, based on the carry signal of Can be included.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, the degaussing power supply device 10 rectifies an alternating current from an alternating current power supply 12 into a direct current in a rectifier circuit 14 and supplies the rectified direct current to an excitation coil 18 via a switching circuit 16. The present invention is applied to an apparatus that executes a so-called loop damping demagnetization method in an electromagnetic chuck.
[0022]
The AC power supply 12 is a commercial AC power supply, and the rectifier circuit 14 is a full-wave rectifier circuit or a half-wave rectifier circuit. The switching circuit 16 is a polarity switching circuit including a pair of relays that switch the energization direction (that is, DC polarity) to the exciting coil, and an energization circuit that drives these relays synchronously. Alternatively, the switching circuit 16 may include a bridge circuit using a plurality of transistors, as described in, for example, Japanese Patent Laid-Open No. 5-198436. The exciting coil 18 is an exciting coil for selectively setting the magnetic attraction surface, that is, the work surface of the electromagnetic chuck in an excited state and a non-excited state.
[0023]
In the following description, it is assumed that the rectifier circuit 14 is a full-wave rectifier circuit that converts a power supply voltage as shown in FIG. 2A to a DC voltage as shown in FIG.
[0024]
The demagnetizing power supply 10 detects the period of alternating current supplied from the alternating current power supply 12 to the rectifier circuit 14 in the period detection circuit 20, and outputs the pulse signal S 1 output from the period detection circuit 20 and the memory circuit 22. A control signal S3 for driving the switching circuit 16 is generated in the output synchronization circuit 24 based on the designation signal S2. The pulse signal S <b> 1 is a synchronous pulse synchronized with the alternating current from the alternating current power supply 12.
[0025]
The cycle detection circuit 20 detects a zero point of the input AC voltage (or current) and outputs a pulse signal S1 corresponding to the zero point. As such a period detection circuit 20, a general zero point detector that generates a pulse signal at the position of the zero point of the input voltage using a photocoupler can be used. As shown in FIG. 2 (C), the pulse signal S1 output from the cycle detection circuit 20 is synchronized with the AC power supply voltage AC shown in FIG. 2 (A) and rectified direct current shown in FIG. 2 (B). It has a waveform synchronized with the AC voltage component in the voltage DC.
[0026]
The memory circuit 22 stores one or more demagnetization patterns. Each demagnetization pattern is information for generating a damped alternating magnetic field for demagnetization from the exciting coil 18. Each demagnetization pattern includes a plurality of instruction signals composed of a combination of an operation designation signal S2 that designates the energization direction of the switching circuit 16 and a time designation signal S4 that designates the energization time to the exciting coil 18.
[0027]
The operation designation signal S2 is a signal that designates the polarity of the direct current supplied to the exciting coil 18, and is used as a signal for alternately switching the energization direction (polarity). On the other hand, the time designation signal S4 is a signal for designating a time for actually supplying DC to the exciting coil 18.
[0028]
An example of the operation designation signal S2 is shown in FIG. 2D, and an example of the control signal S3 is shown in FIG. As shown in FIG. 2D, the operation designation signal S2 has a slightly longer time width than the actual energization time (control signal S3) to the exciting coil 18.
[0029]
The time designation signal S4 is the number of pulse signals S1. For this reason, in Japan, since the frequency of the commercial AC power supply is 50 Hz or 60 Hz, one energization time can be designated by the number of generations of the pulse signal S1.
[0030]
Each demagnetization pattern is also temporarily energized at the start of the demagnetization operation and between temporally adjacent energization periods (between adjacent positive and reverse excitation periods and when the energization direction is switched). Including the excitation suspension period. Each excitation pause period is for temporarily interrupting energization to the excitation coil 18, and is designated by an excitation pause signal. Each excitation pause signal includes a combination of a pause instruction signal for instructing the output synchronization circuit 24 to stop energization of the excitation coil 18 and a time designation signal S4 for specifying the excitation pause period.
[0031]
Each demagnetization pattern also includes an end instruction period for instructing to that effect at the end of the demagnetization operation. This end instruction period is indicated by an end signal S10 output at the end of the degaussing operation (last).
[0032]
The instruction signal, each excitation stop signal, and the end signal are recorded at one address, or are divided and recorded at two or more consecutive addresses. Each excitation pause signal and end signal are for designating or instructing excitation pause, and may be considered as a kind of instruction signal.
[0033]
The memory circuit 22 sequentially stores one or more demagnetization patterns as described above in consecutive addresses for each demagnetization pattern so that the energization direction to the excitation coil 18 is alternated and the energization time is reduced. . An example of the demagnetization pattern stored in the memory circuit 22 is shown in FIGS. The time designation signal S4 in the memory circuit 22 is supplied to the counting circuit 26.
[0034]
As shown in FIG. 2D, the operation designation signal S2 has a slightly longer time width than the actual energization time to the exciting coil 18, and the number of pulse signals S1 corresponding to the time designation signal S4 is It disappears when it is generated. As shown in FIG. 2E, the output synchronization circuit 24 has a time width from when the first pulse signal S1 is received after receiving the operation specifying signal S2 until the operation specifying signal S2 disappears.
[0035]
The counting circuit 26 receives the time designation signal S4 from the memory circuit 22, presets the received time designation signal S4, starts counting the pulse signal S1 from the period detection circuit 20, and receives the number of received pulse signals (count value). ) Reaches the value corresponding to the time designation signal S4, and the step of outputting the pulse-like carry signal S5 to the address change signal generation circuit 28 and returning to the initial state is executed every time the time designation signal S4 is received.
[0036]
The address change signal generation circuit 28 amplifies the received carry signal S5, and designates the amplified signal as an address change signal S6 for advancing the address designated in the memory circuit 22 to the address successively subsequent to the selected demagnetization pattern. While outputting to the circuit 30, it supplies to the counting circuit 26 as the reset signal S7 which returns the counting circuit 26 to an initial state.
[0037]
The count circuit 26 is reset each time it receives the reset signal S7 from the address change signal generation circuit 28, and returned to the initial state. The counting circuit 26 may be reset by a carry signal S5 output by itself.
[0038]
The address specifying circuit 30 is a so-called address circuit that specifies an address to which a signal is to be output to the memory circuit 22. In addition to the address change signal S6, the address designation circuit 30 includes an initial address S8 set in the initial address setter 32, a demagnetization start signal S9 supplied to the terminal 34, and an end signal S10 output from the memory circuit 22. And receive.
[0039]
The initial address setting unit 32 designates the first address of the degaussing operation with a predetermined demagnetization pattern, and a switch such as a digital switch or a rotary switch is used. The demagnetization start signal S9 is a signal for instructing the start of the demagnetization operation, and is input by a changeover switch (not shown) provided in the apparatus. The end signal S10 is a signal for instructing to end the degaussing operation by the demagnetization pattern when one demagnetization process is completed, and is output from the memory circuit 22.
[0040]
When the demagnetization start signal S9 is input to the terminal 34, the address designating circuit 30 first sets the initial address S8 to output the signal in the address corresponding to the initial address S8 set in the initial address setting unit 32 from the memory circuit 22. The corresponding address signal S11 is supplied to the memory circuit 22. Thereafter, the address designating circuit 30 advances the address signal S11 supplied to the memory circuit 22 to the next address each time the address change signal S6 is input.
[0041]
As the addressing circuit 30 as described above, the initial address signal S8 is preset by the input of the demagnetization start signal S9, and then the step is advanced every time the signal S6 is received, and the operation is stopped by receiving the end signal S10. Thus, a counter that returns to the initial state can be used.
[0042]
In the power supply device 10, when the power is turned on, the direct current DC shown in FIG. 2B is output from the rectifier circuit 14, and the pulse signal S 1 shown in FIG. 2C is output from the period detection circuit 20. Has been.
[0043]
When a changeover switch (not shown) is switched to positive excitation in a state where the power is turned on, the power supply device 10 energizes the excitation coil 18 in the positive direction. Thereby, the magnetic action surface of the electromagnetic chuck is placed in an excited state, and the workpiece is magnetically attracted to the magnetic action surface.
[0044]
When the above-mentioned changeover switch is turned off in a state where the power is turned on, the power supply device 10 stops energizing the exciting coil 18. Thereby, the magnetic action surface of the electromagnetic chuck is placed in a non-excited state, and the workpiece can be removed from the magnetic action surface.
[0045]
However, since the magnetism remaining on the workpiece differs depending on the material of the workpiece, it may not be possible to remove the workpiece from the magnetic action surface simply by turning off the changeover switch. Also, depending on the workpiece, it is desirable to remove residual magnetism. In such a case, the changeover switch is switched to demagnetization, whereby the workpiece and the electromagnetic chuck are demagnetized.
[0046]
If the changeover switch is switched to demagnetization while the power is turned on, the demagnetization start signal S9 is input to the addressing circuit 30, so the addressing circuit 30 first stores the address signal S11 corresponding to the initial address S8 in the memory. Output to the circuit 22. As a result, the excitation pause signal is output from the memory circuit 22 to the output synchronization circuit 24 instead of the operation designation signal S2, so that the excitation coil 18 is not energized. Since the time designation signal S4 is output to the counting circuit 26, the counting circuit 26 presets the time designation signal S4 and starts counting the pulse signal S1.
[0047]
When the count value of the counting circuit 26 reaches the value specified by the time specifying signal S4, the carry signal S5 is output from the counting circuit 26, and the signals S6 and S7 are output from the address change signal generating circuit 28. As a result, the counting circuit 26 is reset, and the addressing circuit 30 advances the address signal S11 output to the memory circuit 22 by one.
[0048]
When the first excitation pause signal is stored at a plurality of addresses, the power supply apparatus 10 executes the above process a plurality of times.
[0049]
When the first address storing the instruction signal including the operation designation signal S2 and the time designation signal S4 is designated by the address signal S11, the power supply device 10 proceeds to the first excitation process. The first excitation process is performed as follows.
[0050]
First, since the instruction signal in the address corresponding to the address signal S11 is output from the memory circuit 22, the counting circuit 26 presets the time specifying signal S4 in the output instruction signal and starts counting the pulse signal S1. . The output synchronization circuit 24 outputs a control signal S3 to the switching circuit 16 based on the pulse signal S1 and the operation designation signal S2. Thus, during the first excitation process, the excitation coil 18 is energized in a predetermined direction, and the electromagnetic chuck is placed in a normal or (reverse) excitation state.
[0051]
Next, when the count value of the counting circuit 26 reaches the value specified by the time specifying signal S4, the carry signal S5 is output from the counting circuit 26, and the signals S6 and S7 are output from the address change signal generating circuit 28. As a result, the counting circuit 26 is reset, and the addressing circuit 30 advances the address signal S11 output to the memory circuit 22 by one.
[0052]
When the operation designation signal S2 and the time designation signal S4 are stored at a plurality of addresses, the power supply apparatus 10 performs the above operation a plurality of times. When the first address storing the intermediate excitation stop signal is designated by the address signal S11, the power supply apparatus 10 proceeds to the intermediate excitation stop process.
[0053]
As a result, when the operation designation signal S2 ends, as shown in FIG. 2, the operation designation signal S2 is synchronized with the generation of the pulse signal S1, and is synchronized with the AC component from the power source and the AC component in the rectified DC DC.
[0054]
As shown in FIG. 2E, the control signal S3 is output from when the first pulse signal S1 is supplied after the operation specifying signal S2 is supplied until the operation specifying signal S2 disappears. For this reason, at the time of extinction, it synchronizes with the generation of the pulse signal and synchronizes with the AC component from the power source and the AC component in the rectified DC DC. And synchronized with the AC component in the rectified DC.
[0055]
In the intermediate excitation stop step, an excitation stop signal in the address corresponding to the address signal S11 is first output from the memory circuit 22, so that the output synchronization circuit 24 stops the energization of the excitation coil 18 and counts the operation designation signal. The circuit 26 presets the supplied time designation signal S4 and starts counting pulse signals.
[0056]
Next, when the count value of the counting circuit 26 becomes the value specified by the time specifying signal S4, the carry signal S5 is output from the counting circuit 26, the signals S6 and S7 are output from the address change signal generating circuit 28, and the counting circuit 26 Is reset, and the addressing circuit 30 advances the address signal S11 output to the memory circuit 22 by one.
[0057]
When the intermediate excitation pause signal is stored at a plurality of addresses, the power supply apparatus 10 performs the above operation a plurality of times and then proceeds to the second excitation process. The second excitation process is executed in the same manner as the second first excitation process except that the energization direction to the excitation coil 18 is different. Thereafter, an intermediate excitation suspension process is executed again.
[0058]
The first and second excitation steps are executed a plurality of times with an intermediate excitation pause step in between. When such a process is executed a plurality of times, the power supply apparatus 10 proceeds to the final end process.
[0059]
This end process starts when the address storing the end signal S10 is designated by the address signal S11. An end signal S10 in the address corresponding to the address signal S11 is output from the memory circuit 22 to the address specifying circuit 30, whereby the power supply device 10 ends the degaussing operation and returns to the standby state.
[0060]
The energization direction to the excitation coil 18 is switched alternately between the forward direction and the reverse direction for each excitation process. Also, the excitation time is gradually reduced. As a result, as shown in FIG. 3 (A), the alternating alternating voltage whose polarity alternates and gradually attenuates is supplied from the output synchronization circuit 24 to the exciting coil 18.
[0061]
As described above, when the control signal S3 is synchronized with the pulse signal S1, the energization time for the control excitation term is the same since the start and end of energization of the excitation coil 18 are synchronized with the AC component in DC. If so, the same current is always supplied to the exciting coil, so that demagnetization can be reliably performed.
[0062]
In the power supply device 10, the address that is initially specified for the memory circuit may be fixed. In this case, it is not necessary to use the address setting unit 32 that can selectively set the initial address, and the setting value of the address setting unit 32 may be fixed.
[0063]
However, it is preferable that the initial address setting unit 32 can be selectively set. By doing so, the degaussing operation is not performed from the beginning (first item) of one demagnetization pattern, and an arbitrary intermediate point is selected according to the material and size of the demagnetization object as shown in FIG. Since one degaussing pattern stored in the memory can be used in common for a plurality of types of demagnetization, the degaussing stored in the memory circuit can be performed. Even if the number of patterns is small, it is possible to demagnetize many kinds of demagnetization objects having different materials and sizes.
[0064]
A plurality of demagnetization patterns corresponding to the material and size of the workpiece to be demagnetized may be stored in the memory circuit, and the initial address setting unit 32 may be used for selecting a desired demagnetization pattern. In this case, the degaussing operation by the degaussing pattern using the address set in the initial address setting unit 32 as the start address (first address) is executed from the beginning of the degaussing pattern.
[0065]
Referring to FIG. 4, the power supply device 40 further energizes the exciting coil 18 based on the polarity switching number setting unit 42 for setting the number of times of switching in the energization direction and the operation designation signal S2 (or the control signal S3). And a counting circuit 44 for counting the number of times. The count circuit 44 generates an operation stop signal S12 for stopping the operation of the power supply device 10 when the count value reaches the value set in the polarity switching number setting unit 42. The operation stop signal S12 is supplied to the addressing circuit 30.
[0066]
In the power supply device 40, the demagnetization start signal (for example, the i-th term) is set in the initial address setting unit 32 and the number of switching times (for example, n) is set in the polarity switching number setting unit 42. When S9 is input to the addressing circuit, as shown in FIG. 3B, the addressing circuit 30 starts degaussing operation from the i-th term.
[0067]
The degaussing operation is started by outputting the address signal S11 corresponding to the address where the information of the i-th item is stored from the address designating circuit 30 to the memory circuit 22. When the number of times of switching the polarity is n, the operation stop signal S12 is supplied to the addressing circuit 30, so that the addressing circuit 30 ends the degaussing operation in the same manner as when the end signal S10 is supplied thereto. Return to standby.
[0068]
According to the above, the number of times of switching the energization direction can be set according to the material and size of the demagnetization target object, and since it can be executed in the middle of one demagnetization pattern, it is stored in the memory. A single degaussing pattern can be used in common for multiple types of degaussing. As a result, even if the number of degaussing patterns stored in the memory circuit is small, many types of degaussing objects with different materials, sizes, etc. Can be demagnetized.
[0069]
5 and 6 show an embodiment of a demagnetization pattern used in a power supply device using two relays CR1 and CR2 as switching means in a switching circuit. In the demagnetization pattern shown in FIG. 5, the addresses and data are shown in hexadecimal numbers of 4 bits at the upper and lower parts. For example, the address FF corresponds to 1111 and 1111.
[0070]
The upper 4 bits in the data (for example, the “3” bit of the data 3F) are bits that specify the energization state (non-energized and energized direction) of the relay, and the lower 4 bits (for example, “3” of the data 3F). F ″ bit) is a bit for designating the number of generation of the pulse signal S1.
[0071]
For this reason, for example, the addresses FD, FC, FB, FA mean that reverse excitation is performed while 58 pulse signals S1, which is the sum of the lower 4 bits, are generated. In this case, the energization time is 58 t, where t is the period of the pulse signal S1.
[0072]
In the above embodiment, the output synchronization circuit 24, the counting circuit 26, the address change signal generating circuit 28 and the addressing circuit 30, or in addition to them, the counting circuit 44 may be replaced with a computer or a central processing unit (CPU). . When replacing them with a computer, the internal memory of the computer may be used as the memory circuit 22.
[0073]
The present invention is not limited to the above embodiments. For example, the present invention can be applied not only to a demagnetizing power supply device used for an electromagnetic chuck but also to a power supply device used for a general demagnetization device.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electric circuit showing an embodiment of a power supply device according to the present invention.
FIG. 2 is a diagram showing a waveform of an electric signal in the apparatus of FIG.
FIG. 3 is a diagram showing an example of a waveform of an excitation voltage supplied to an excitation coil in the apparatus of FIG.
FIG. 4 is a block diagram of an electric circuit showing another embodiment of the power supply device according to the present invention.
FIG. 5 is a diagram illustrating an example of a part of a demagnetization pattern stored in a memory circuit.
6 is a diagram showing the remaining part of the demagnetization pattern following the demagnetization pattern shown in FIG. 5. FIG.
[Explanation of symbols]
10, 40 Power supply for degaussing
12 Commercial AC power supply
14 Rectifier circuit
16 switching circuit
18 Excitation coil

Claims (6)

A demagnetizing power supply apparatus for supplying a direct current output from a rectifying circuit for rectifying an alternating current to an excitation coil by alternately switching an energization direction in a switching circuit so as to generate a decaying alternating magnetic field for demagnetization in the excitation coil. A cycle detection circuit that detects a cycle of the alternating current supplied to the rectifier circuit and generates a pulse signal corresponding to the cycle, a plurality of operation designation signals that designate the energization direction of the excitation coil, and the excitation coil A memory circuit in which at least one demagnetization pattern including a plurality of time designation signals for designating the energization period is stored, and a processing circuit for outputting a control signal synchronized with the AC cycle to the switching circuit,
The processing circuit designates a predetermined address in the memory circuit, outputs a signal in the address from the memory circuit, counts a pulse signal output from the period detection circuit, and determines the number of pulse signals as the memory signal. A demagnetizing unit that changes an address designated to the memory circuit each time it matches a value corresponding to a time designation signal obtained from the circuit, and outputs the control signal based on the output operation designation signal and the pulse signal. Power supply. The processing circuit receives an address specifying means for outputting an address signal for specifying an address storing a signal to be output to the memory circuit, the time specifying signal and the pulse signal, and the received pulse signal. Counts each time the count value reaches a value corresponding to the received time designation signal, and outputs an address change signal for changing the address signal output from the address designating means to the next address signal according to the demagnetization pattern. The demagnetizing power supply device according to claim 1, further comprising: means, and output synchronization means for outputting the control signal based on the operation designation signal and the pulse signal. Furthermore, an initial address setter that selectively sets an initial address of a demagnetization pattern to be used is included, and the processing circuit designates the initial address set in the initial address setting means in the memory circuit, and then the number of pulse signals is 3. The demagnetizing power supply device according to claim 1, wherein an address designated for the memory circuit is changed every time a value corresponding to a time designation signal obtained from the memory circuit is matched. 4. The processing circuit according to claim 3, wherein an initial address set in the initial address setter is used as a start address among degaussing patterns including the initial address set in the initial address setter, and is executed from the start address. 5. Power supply for degaussing. Furthermore, a switching number setting device for setting the number of switching of the energization direction is included, and the processing circuit further counts the number of energizations to the exciting coil based on the control signal or the operation designation signal, and the count value is 5. The demagnetizing power supply device according to claim 2, further comprising second counting means for generating an operation stop signal for stopping the operation of the processing circuit when a value set in the switching number setting device is reached. The counting means receives the time designation signal and the pulse signal, counts the received pulse signal, and outputs a carry signal each time the count value reaches a value corresponding to the received time designation signal. And based on the carry signal from the counting means, the address designation signal output from the address designation means is changed to the next address designation signal according to the demagnetization pattern, and the address change signal for clearing the count value of the counting means 6. The demagnetizing power supply device according to claim 2, further comprising an address change signal generating means for outputting.

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