JPS5947387B2 - Bubble memory drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION J The present invention relates to a bubble memory drive circuit used for applying a rotational driving magnetic field to a magnetic bubble memory to transfer magnetic bubbles.

The device that generates the rotating magnetic field that drives the magnetic bubbles consists of an X drive coil L and a Y drive coil arranged perpendicularly as shown in Figure 1.
Drive coil L.

A rotating magnetic field is generated by passing currents having a phase difference of 900 degrees through these drive coils. A sine wave, a triangular wave, or the like is used as the waveform of this current. In the case of a sine wave, a circular rotating magnetic field is obtained, but in the case of a triangular wave current as shown in FIGS. 2A and 2B, a rectangular rotating magnetic field H as shown in FIG. 3 is obtained. By the way, FIG. 4 shows a conventional example of a drive circuit that supplies such a triangular wave current to one of the drive coils.

In the figure, + and V- are power supply terminals, T1 to T4 are transformers that transmit input pulse signals, Trl to Tr4 are transistors, D1 to D3 are diodes, and L1 is an example of the x drive coil among the drive coils. It is. Diodes D5 to D8 are connected in antiparallel to transistors Trl to Trll, these four pairs of transistors and diodes are connected to a bridge circuit, and drive coil L1 is connected to the AC terminal of this bridge. To explain the operation of this triangular wave drive circuit, first, an input signal P having a waveform as shown in FIG. 5a is used.

passes through transformers Tl and T4 to transistors Trl and Tr.
When simultaneously applied to the bases of transistors Trl and T, the base current 1 flows as shown by the solid line in Figure b, and the transistors Trl and T
r4, is turned on and v+-Trl-D1-L1-D4
A current flows through the path -Tr4-V-. This current is collector current 1 of transistors Trl and Tr4. becomes a triangular wave current as shown in c in the figure. This is due to the integral effect due to the inductance of the drive coil L1 (L ton = E..l
″Dt.゜.i=[FEdO.

Signal P. is no longer applied to the bases of transistors Trl and Tr4, transistors Trl and Tr4 are turned off, and D7-L is turned off due to the back electromotive force of x drive coil L1.
Since the current flows along the path 1-D6, the current waveform flowing through the X drive coil L1 is as shown in FIG. 5d. Then, the point at which this triangular wave current attenuates to O, that is, the signal P
. The pulse width of W is approximately 2 W after the signal is input.
At the point in time, the signal P1 with the same waveform is transferred to the transformers T2 and T.
3 through transistors Tr2, Tr3 . added to,
Similarly, a current as shown in the figure e flows through the x drive coil L1. As a result, a triangular wave current as shown in FIG. 2a is obtained as a whole. The triangular wave current for the Y drive coil L2 shown in FIG. 2b is also generated by a similar circuit. By the way, the conventional saturation type switching circuit shown in FIG. 4 has the following problems.

That is, the collector current is a triangular wave as shown in Figure 5e,
Therefore, the base current required to flow this current may be a triangular wave having a similar shape. Nevertheless, since the base current actually supplied is a rectangular wave shown in FIG. 5b, the shaded portion is excessive. Excess carrier is accumulated in the base and signal P is generated. When the current is turned off, the current flows backward and disappears as indicated by Ib in FIG. 5b. The period T during which this base current flows
During the period 5, the transistor is on and power is supplied from the power supply. Therefore, the collector current is 1. The triangular waveform of is the signal P. Even after it is turned off, it continues to increase as shown in FIG. 5c, and the peak position of the triangular wave moves to a position delayed in time. The rotating magnetic field H″ due to such triangular wave current is
As shown in the figure, the rectangular rotating magnetic field H is shifted by a certain angle, resulting in a phase shift. The amount of movement of the peak position of this triangular wave also changes depending on the power supply voltage. In other words, in bubble memory operation margin tests, tests, etc., the strength of the bias magnetic field and driving magnetic field applied to the bubble memory is varied to check for normal abnormalities in bubble propagation and other operations in each state. To change the collector current, change the voltage of the power supply + and V-. The method is to adjust the size of. In this case, the input signal P. , Pl correspond to the driving frequency of the bubble memory, so they are assumed to be unchanged. On the other hand, for example, when the collector power supply becomes large, a large amount of base current is consumed, so the excess carrier in the base decreases proportionally, and therefore reverse flow and extinction become faster, and the shift in the peak position of the triangular wave becomes smaller. . Figure 7 shows this relationship, where V is the waveform when the power supply voltage is high, and V
, is the waveform when the value is low. If there is a change in the peak position, the shift amount of the driving magnetic field shown in FIG. 6 will also change, and on the other hand, since tests, tests, etc. are performed in synchronization with the driving of the bubble memory, this causes a difficult problem. The drawbacks of the conventional circuits described above can be alleviated by using transistors with short storage times.

However, in large drive circuits used in magnetic bubble memory devices, when the operating frequency is increased or a large current is passed, the back electromotive force generated in the drive coil increases, and the withstand voltage, allowable current, and collector loss to cope with this increase. A transistor with a large storage time does not exist in a transistor with a small storage time. In other words, there is an antinomic relationship between transistor power and storage time. The present invention attempts to solve the problems of the prior art, and aims to provide a bubble memory drive circuit with a large current and high withstand voltage, which does not cause deviation in the peak position of the triangular wave current.

That is, the bubble memory drive circuit of the present invention, as shown in FIG. 8, is an improved version of the conventional bubble memory drive circuit shown in FIG. 4, and its operating principle will be explained with reference to FIG. 9.

FIG. 9a shows an improved portion of the bubble memory drive circuit of the present invention shown in FIG. 8, centering on the transistor Tr, and FIG. 9b shows an equivalent circuit thereof.

Now, in the present invention, in order to eliminate the disadvantage of the prior art caused by the transistor becoming saturated, it is made to be unsaturated.

For this reason, the circuit of the present invention receives the pulse signal P as shown in FIG. 9a. The secondary winding of the transformer T1 to which is input is further wound so that the base connection end is at the midpoint, and the end of this winding wire portion 11 is connected to a diode D, which prevents reverse flow of current from the power supply Vf. It is connected to the collector of the transistor Trl through a series circuit with a resistor R for determining the degree of saturation of the transistor Trl. ．． The same applies to the other transistors Tr2 to Tr4. These winding portions 1,-1. The number of turns in the remaining part of the secondary winding (
The winding should be the same as the part before winding. The operation of this circuit is as follows.

That is, No. 10. A signal P with a pulse waveform shown in Figure a. When is applied to the transformer T1, the base current Ib immediately flows and the transistor Trl is turned on, but along with this, the collector current flows to the transistor Trl through the diode D9 and the resistor R1, and the current that has flowed as the base current Ib becomes The current becomes almost the current IR passing through the resistor R.
FIG. 10c shows the waveform of this current IR. The base current decreases by this amount of current, that is, by the amount shown by diagonal lines in FIG. The relationship between the base current Ib and the current IR flowing through the resistor R is more clearly shown in the equivalent circuit of FIG. 9b. That is, the secondary winding and winding coil section 11 between the base and emitter of the transistor can be replaced with DC power supplies, and these power supplies will cause the base current Ib and the current IR flowing through the resistor R1 to be as shown in the figure. However, a current (Ib+IR) flows in the power supply section between the base and the emitter, which corresponds to the secondary winding.
Since this current (Ib+IR) roughly corresponds to the base current of the conventional circuit, the current I. only,
It can be said that the base current Ib has decreased. By the way, as is clear from this equivalent circuit, the magnitude of the base current Ib is determined by the main resistance R in the circuit through which the current IR flows.
affected by.

That is, as shown in FIG. 11, when the resistance R1 is relatively small, the base current Ib shows the change shown by the solid line, but as the resistance R1 is set to a large value, the base current Ib changes to a state close to saturation switching, which is shown by the broken line in the same figure. The current changes as follows. Therefore, by choosing the resistance R,
It is possible to control the saturation depth of the transistor. A low resistance of about 10-odd ohms is suitable for the resistance R, but of course it may vary somewhat depending on the type of transistor, the number of windings of the secondary winding of the transformer, and the power supply voltage. The reason why the base current Ib decreases rapidly and then increases with time as shown in FIG. 10b is because the collector current Ic flowing through the drive coil increases with time as described above, so the required base current This is because Ib also increases.

As described above, the base current Ib can be limited to the amount necessary to flow the collector current Ic by setting the resistor R1.
As a result, the amount of carrier accumulation in the base region is small, and the peak position of the triangular wave current flowing through the collector is at the first
As shown in FIGS. 0a and 0d, the pulse waveform can be made to approximately coincide with the point in time when it is turned off, and the shift of the rotational driving magnetic field can be suppressed.

Furthermore, since the number of accumulated carriers can be reduced, even if the power supply voltage is changed, the peak position will hardly shift. Furthermore, since the storage carrier can be reduced, a transistor with a long storage time and a high withstand voltage and large current can be used, which is very advantageous in terms of increasing the capacity. Note that the pulse signal P.

disappears and the transistor Trl turns off, V''-R
, -D9-T, and the secondary windings -D, -L, . Block current. As mentioned above, at this time, a triangular wave current flows through the X drive coil L, from the diode D through the diode D6, and a pulse signal P1 with a phase shift of 180° is generated.
is applied to the transformers T2 and T3, a triangular wave current flows in the opposite direction to the X drive coil L, and as a whole, a triangular wave current as shown in Figure 10e flows through the X drive coil. be. Collector clamp type and base clamp type unsaturated circuits are known to prevent transistor saturation.

The former has a collector connected to a power supply and ground via a pair of diodes, and the latter has a base and collector connected to an input end via a pair of diodes, and thus has a different configuration from the present invention. The former collector clamp type uses a diode to clamp the collector to ground. Since the voltage applied to the load is limited, it is not preferable to apply it to a triangular wave drive circuit of a bubble memory because the drive coil voltage and therefore the current are limited. This method also requires a separate power supply for the clamp. The former base clamp type conducts a pair of diodes based on their own potential relationship, one of which is a silicon diode,
The other is a germanium diode, which has a different forward voltage drop, so the difference is used to reverse bias between the base and collector, and a separate power supply is not required, but the forward voltage drop varies depending on the type. It is fixed and the reverse bias voltage cannot be set freely. Also, if a diode is inserted into the base, when the diode is turned off by the signal potential, the base will be in a floating state, and it will take time for the carrier remaining between the emitter and the base to disappear, and it will take time for the transistor to turn off. Ka・ru. In the circuit according to the invention, all such drawbacks are eliminated. As described above, the bubble memory drive circuit of the present invention further winds up the secondary side of the transformer of the conventional circuit, connects this and the collector with a diode and a resistor, and applies feedback to prevent the transistor from becoming deeply saturated. This makes it possible to use transistors with long storage times, especially high-speed switching transistors with large breakdown voltages, currents, and collector losses, and it is now possible to use transistors with the same characteristics in parallel to compensate for the lack of capacity, unlike in the past. This eliminates the inconvenience of using the device, and it is particularly useful for high-voltage, large-current drive circuits.

Furthermore, the drive circuit of the present invention is advantageous when the collector current during the on period is limited, such as for drive coils driven by triangular waves, and is useful for testing magnetic bubble memory devices in which the magnitude of the rotating magnetic field is changed by switching the power supply voltage. When used in a machine, etc., it is extremely suitable because there is no shift in the peak position of the triangular wave and therefore no shift in the rotating magnetic field.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the arrangement of the drive coil for generating a rotating magnetic field, Figure 2 is a waveform diagram showing the triangular wave current flowing through the drive coil, Figure 3 is a diagram showing the normal rotating magnetic field locus, and Figure 4 is Circuit diagram showing a conventional drive circuit supplying a triangular wave current, No. 5
Figures a-e are waveform diagrams of the current in each part of this circuit, Figure 6 is a diagram showing the locus of the rotating magnetic field when the peak position of the triangular wave is shifted, and Figure 7 is a diagram showing the locus of the rotating magnetic field when the peak position of the triangular wave is shifted due to fluctuations in the power supply voltage. Figures 8 to 11 are diagrams explaining the bubble memory drive circuit of the present invention, Figure 8 is a drive circuit diagram, and Figures 9A and b are part of this circuit. 10A to 10E are current waveform diagrams of various parts of this circuit diagram, and FIG. 11 is an explanatory diagram showing the relationship between the base current and the resistor R. P in the figure.

Claims (1)

[Claims] 1. In a triangular wave bubble memory drive circuit in which four pairs of transistors and diodes connected in antiparallel to the transistors are connected in a bridge shape, and a drive coil is connected between the alternating current terminals, the base of each transistor is Further wind the secondary winding of the signal input transformer connected between the emitters,
1. A bubble memory drive circuit characterized in that a wound end of the bubble memory drive circuit is connected to a collector of the transistor through a diode and a resistor to drive the transistor in a non-saturated manner. 2 Transformer T_1 that transmits input pulse signals of the same phase
, T_4, and transformers T_2 and T_3 that transmit input pulse signals whose phase is shifted by 180 degrees from the above-mentioned phase.
Transistors Tr_1, Tr_2, and Tr whose bases and emitters are connected to the secondary windings of each of the transformers, respectively.
One end of _3, Tr_4 is connected to the emitter of transistor Tr_1 and the collector of transistor Tr_3 via diodes D_1 and D_3, respectively, and the emitter of transistor Tr_2 and the collector of transistor Tr_3 are connected to each other through diodes D_1 and D_3, respectively.
a drive coil L_1 whose other end is connected to the collectors of the transistors Tr_4 through diodes D_2 and D_4, respectively; and a diode which is connected in antiparallel to the transistors Tr_1 to Tr_4 and supplies current to the drive coil L_1 when the pulse signal is cut off. D_5 to D_8 and the transistor Tr
_1 and Tr_2 collectors and transistor Tr_3
and a DC power supply connected to the emitter of Tr_4, the secondary windings of each of the transformers T_1 to T_4 are further wound so that the base connection end of each transformer is at the midpoint. , the winding ends thereof are connected to the collectors of each of the transistors via diodes D_9 to D_1_2 that prevent reverse flow of current from the power supply and resistors R_1 to R_4 that set the degree of saturation of the transistors Tr_1 to Tr_4. The bubble memory drive circuit according to claim 1, characterized in that: