JPS5998371A - Resonance type coil driving circuit - Google Patents

Abstract

PURPOSE:To supply a sinusoidal current having a prescribed amplitude to a resonance coil at all times with simple constitution by controlling the Q of the resonance circuit via a control transistor (TR) in response to a current flowing to the resonance coil. CONSTITUTION:A series resonance circuit formed by a capacitor 2 and a coil 1 of a resonance type coil driving circuit for rotating magnetic field generation of a magnetic bubble memory element is driven by a DC power supply 5, and P and N type switching TRs 3, 4. The current flowing to the coil 1 is smoothed by a diode 6 and a capacitor 7, a voltage corresponding to the current flowing to the coil 1 via voltage dividing resistors 8, 9 is generated and impressed to a gate of the control TR11. Then, if the coil current is decreased because of voltage fluctuation of the power supply 5 and variation in the characteristics of the TRs 3, 4, a gate-source voltage of the TR11 is reduced and the drain current is decreased, the Q of the resonance circuit is large, and then the coil current is corrected into a prescribed value. This is the same as the case with the increased coil current, the sinusoidal current having a prescribed amplitude is applied always to the resonance coil with simple constitution.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a drive circuit for a rotating magnetic field generating coil of a magnetic bubble memory device, and particularly relates to a resonant coil drive circuit suitable for high stability excitation. be.

[Prior art]

Conventionally, in resonant coil drive circuits, particularly series resonant drive circuits, used to generate rotating magnetic fields in magnetic bubble memory devices, changes in coil resistance due to heat generation in the rotating magnetic field generation coils and changes in ON resistance due to heat generation in switching elements have been observed. Also, fluctuations in the power supply voltage directly cause fluctuations in the coil current, making it difficult to supply a stable rotating magnetic field to the magnetic bubble memory element. In addition, since there are deviations (variations) between components in the coil resistance and ON resistance of switching elements, this method was developed to address the drawbacks such as the need for adjustment work to set the coil current value to a predetermined specified value. The purpose of this is to generate a sine wave current with a constant amplitude even if the rotating magnetic field generating coil or switching element generates heat, the coil resistance or ON resistance of the switching element changes, or the power supply voltage fluctuates. It is an object of the present invention to provide a resonant coil drive circuit for generating a rotating magnetic field, which makes it possible to supply a coil with a rotating magnetic field.

A resonant voltage control circuit for controlling the Q of the resonant circuit is provided in parallel with the magnetized external generation coil.

That is, the present invention provides a resonant coil drive circuit that includes:
The amplitude of the coil current is determined by the Q of the resonant circuit including the resistance of the circuit connected to the coil, and by controlling this Q, the coil current can be held constant and the Q
is the ratio of energy stored to energy consumed during one cycle, and focusing on the fact that Q can be controlled by extracting energy from the resonant circuit, we designed a resonant voltage control circuit as a simple means of extracting energy. .

The figure shows an example of a drive circuit for a resonant coil for generating a rotating magnetic field according to the present invention. In the figure, 1 is a coil wound around a magnetic bubble memory element to generate a rotating magnetic field, and 2 is a capacitor connected in series to this coil 1. Coil 1 and capacitor 2 form a series resonant circuit. are doing. The other end of the capacitor 2 is connected to the drive circuit, and the other end of the coil 1 is grounded. In this case, the resonance frequency of the coil 1 and the capacitor 2 is set to be equal to the frequency of the rotating magnetic field that drives the magnetic bubble. 3 and 4 are a P-channel MO8) transistor and an N-channel MO8) transistor that constitute a drive circuit that drives a series resonant circuit from the coil 1 and capacitor 2, and these transistors 3 and 4 have a period of 1/2 of the rotating magnetic field. It is configured to turn on and off. That is, when transistor 3 is turned on, a sinusoidal current flows in the positive direction (in the direction of the arrow shown by the solid line), and when transistor 4 is turned on, a sinusoidal current flows in the negative direction (in the direction of the arrow shown by the broken line). It is structured so that it flows. By alternately turning on the driving transistors 3.4 in this manner, a sinusoidal current can be caused to flow. Here, the rotating magnetic field stops when the magnetic bubble is not used, and the rotating magnetic field repeats the stop pipe operation. Therefore, the sine wave current also operates and stops. 5 is a transistor 3p4tW-to operate, that is, a sinusoidal current k ji
6 is a diode 1 which is connected in parallel to the coil 1 and causes a resonant voltage km generated across the coil 1 to flow.
．． 7 is a smoothing capacitor that normalizes the rectified voltage.
This diode 6 and the smoothing capacitor constitute a rectifier circuit. 8 and 9 are voltage dividing resistors that detect the rectified voltage and compare it with a preset reference voltage.
constitutes a voltage divider circuit for rectified voltage. 1o is a load resistance, and 11 is an N-channel MO8) transistor that fully controls the rectified voltage in accordance with the divided voltage value. An enhancement type is used in which drain current flows.

In the series resonant drive circuit constructed in this way,
A resonant voltage across the coil that is proportional to the current flowing through the coil 1 is rectified by a diode 6, divided by voltage dividing resistors 8 and 9, and applied to the gate of a control transistor 11.

Therefore, when the coil current decreases due to heat generation in the coil 1 and switching transistors 3 and 4 and a decrease in the power supply voltage of the DC power supply 5, the gate-source voltage VCS of the control transistor 11 decreases, and the drain current of the transistor 11 decreases. decreases. In this case, since the decrease in drain current increases the Q of the resonant circuit, the coil current increases, and the decrease in coil current due to the increase in coil resistance due to heat generation and the ON resistance of switching transistors 3 and 4 is completely compensated for. Further, when the voltage of the DC power supply 5 increases and the coil current increases, the gate voltage of the control transistor 11 increases and the drain current increases, so that the Q of the resonant circuit decreases. Therefore, the decrease in Q is due to coil 1
In order to reduce the current, the increase in the current flowing through the coil 1 due to the increase in the voltage of the power supply 5 is corrected.

In this case, the control transistor 11 has a conductance gm
If a large one is used, when the gate-source voltage VGS of the transistor 11 becomes larger than the threshold voltage VTR, a large drain current flows through the transistor 3, lowering the Q of the resonant circuit and reducing the total current of the coil 1. . As a result, the gate-source voltage VC of the transistor 11
S is lowered, and the drain current is always controlled so that the gate-to-earth voltage VCS approaches the threshold constant voltage VTR.

Furthermore, when the gate-source voltage VGS becomes smaller than the threshold voltage VTR, the drain current stops flowing, so the current flowing through the coil 1 increases and the gate-source voltage VCS increases. The drain current flows so as to be equal to the threshold voltage vTH. Therefore, the resonant voltage across the coil 10 is always maintained at a value obtained by multiplying the threshold voltage VTR by the reciprocal of the voltage division ratio of the voltage dividing resistors 8 and 9. Even if the resistance of the coil 1 or the ON resistance of the switching transistors 3 and 4 changes, it can always be kept constant. In addition,
The load resistor 10 of the control transistor 11 is used to reduce the loss of the transistor 11, and may be omitted in principle.

According to such a configuration, the voltage fluctuation of the power supply 5.

Resistance of coil 1 and switching transistor 3,
Even when fluctuations occur due to heat generation in the ON resistance 4, a sine wave current of constant amplitude can always be passed through the coil 1, so a stable rotating magnetic field can always be supplied to the magnetic bubble memory element.

In the above embodiment, MOS transistors were used as the switching transistors 3 and 4, but it is clear that similar effects can be obtained even when bipolar transistors are used.

It goes without saying that similar effects can also be obtained by using a combination of a bipolar transistor and a Zener diode for the control transistor 11.

Furthermore, if the divided voltage of the voltage dividing resistors 8 and 9 is amplified using an amplifier and inputted to the control transistor 11, the same effect can be obtained even if a low conductance MOS transistor is used as the control transistor. According to the drive circuit, fluctuations in the power supply voltage.

It is possible to eliminate fluctuations in the coil current due to changes in resistance due to heat generation in the rotating magnetic field generating coil and changes in ON resistance of the switching element, eliminating the need for setting and adjusting the coil current value and improving productivity. This has an extremely excellent effect in that a highly reliable magnetic bubble memory device can be obtained.

[Brief explanation of the drawing]

The figure is a diagram showing an example of a drive circuit for a rotating magnetic field generating coil according to the present invention. 1.@Fist/Rotating magnetic field generation coil, 2...Capacitor, 30@...P channel MO8) transistor, 4.
...N-channel MO8) transistor, 6...Φ diode, 7 fist- smoothing capacitor, 8,9-...
Voltage dividing resistor, 10...Load resistance, 11@...N-channel MOS transistor. T>-T) Octopus

Claims (1)

[Claims] One end of the capacitor of a series resonant circuit consisting of a coil and a capacitor is connected to a driving power source, one end of the coil is grounded, and a sinusoidal current is generated by series resonance between the coil and the capacitor, thereby creating a magnetic bubble. In a resonant coil drive circuit for generating a rotating magnetic field that transfers a voltage, a rectifier circuit that rectifies the resonant voltage is provided at a connection point between the capacitor and the coil of the resonant circuit, and a standard that is set in advance by detecting the rectified voltage. 1. A resonant coil drive circuit comprising: a voltage dividing circuit for comparing a voltage; and a transistor for controlling the rectified voltage in accordance with the divided voltage difference.