JPS5823381A - Magnetic bubble detector - Google Patents

Abstract

PURPOSE:To improve the reliability of bubble detection, by changing a sense threshold value at each bubble detection phase in synchronizing with a rotating magnetic field. CONSTITUTION:The presence/absence of bubbles are converted into the difference of voltage drop of a bubble detection element 1. The result is amplified at an amplifier 2, compared with an output of a threshold value power supply 3' at a comparator 4 and decided. A driving phase signal 7 of a rotating magnetic field is inputted to a counter 5 at the pre-stage of the power supply 3' provided D/A transducer mainly and the threshold value during one period is changed with the phase. Since the sense noise level differs depending on two detection phase of ''0'' and ''1'' in one period, the sense threshold value is changed at the two phases and the error in the conversion from an output waveform of the comparator 4 to digital signals ''1'' and ''0'' can be eliminated.

Description

[Detailed description of the invention] The present invention relates to a magnetic bubble memory detection device.

Magnetic bubble (hereinafter abbreviated as bubble) memory stores information expressed by rlJ and rOJ with or without bubbles, and is compared to other magnetic memories such as magnetic disks, magnetic drums, and magnetic tapes. It has no mechanical moving parts and is expected to be a highly reliable memory.

FIG. 1 is an explanatory diagram of a conventional bubble detection device.

In order to realize a bubble detection device economically, a plurality of bubble detection elements 1 and a dummy detection element 1 for noise cancellation are used.
' often uses a set of amplifier 2, threshold power supply 3, and comparator 4 in common. These plurality of bubble detection elements 1 are detected at different times, regardless of whether a changeover switch for selectively detecting one of them is used or not. By detecting bubbles at multiple phases during one cycle of the rotating magnetic field using this type of detection method, it is possible to increase the amount of information read out per unit time.

The invention thus relates to a detection device which reads two or more bits from two or more detection probes 1 during a rotating magnetic field period. Generally, when reading information with a bubble detection device, the presence or absence of bubbles is converted into a difference in voltage drop across the bubble detection element 1. The result is amplified by amplifier 2, and the threshold value
The output of the kIt source 3 is compared with the comparator 4, and the
It is judged as J.

FIG. 2 is an explanatory diagram of the operation of FIG. 1; FIG. 2 shows a case where two bits are detected in one cycle of the rotating magnetic field 21.

sOe, eOs, alo, °1° detection signal 22
In addition to the voltage drop at the bubble detection element, the rotating magnetic field 21
Induction noise due to the voltage and current of the drive coil is superimposed. Although the noise is reduced by using a differential configuration between the active detection element l and the dummy detection element l', the unbalanced component becomes noise that is repeated with the period of the rotating magnetic field. Shita Ka, Te, @o'``o@@t'
@l'o Detection (No. 1 22 G-[Shows a waveform that is difficult to detect above the string wave noise.

Restorer 6 is capacitor 6! and a switch C, which allows only the detection signal of the phase determined by the drive signal n to pass through. Therefore, DCIJ storer 6
The output waveform of is a sample of the noise-superimposed detection signal. This output waveform U is compared with a threshold value by a comparator 4 and quantized into a digital signal of "1° or 10".

In the bubble detection device shown in FIG. 1, the threshold value 5 set by the threshold power source 3 is fixed, and even if it is set optimally at a certain phase, it will deviate from the optimal value at other phases.

Therefore, the output of the comparator 4 is
“There was a loud noise, and two bits malfunctioned.

The reason for this is that the threshold is fixed even though the noise is not constant when reading 2 or more bits in one cycle.

That is, the conventional bubble detection device has a drawback that when attempting to detect a signal of two or more bits in one cycle of a rotating magnetic field, bubble detection cannot be performed with high reliability.

The object of the present invention is to provide a bubble detection device which eliminates the above-mentioned drawbacks.

Therefore, the present invention includes a plurality of detection elements that detect magnetic bubbles in different phases with respect to one rotating magnetic field, an intensifier commonly connected to the plurality of detection elements, and an intensifier that detects magnetic bubbles in different phases with respect to one rotating magnetic field. A magnetic bubble detection device comprising a comparator that compares and quantizes a sense m*, wherein the sense threshold is changed for each bubble detection phase in synchronization with the rotating magnetic field. It is a detection device.

The present invention will be described in detail below using the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention. The difference from Fig. 1 is that the threshold power supply 3' is mainly based on a converter.
The driving phase signal 7 of the rotating magnetic field is inputted to the counter 5 at the front stage of the counter 5, and the threshold value changes with the phase within the - period. This can reduce errors in read data.

FIG. 4 is a diagram showing an example of a detected waveform according to the present invention.

Waveforms 42, 43, and 44 correspond one-to-one to waveforms η and 23° in FIG. 2, respectively. The big difference is that Ichisen is not fixed like Tosenbu. As a result, the difference between the waveform and the threshold 45 is m as shown in the waveform 46.
0a m0a m1a The waveform corresponds to 1.1.

In other words, focusing on the fact that the sense noise level is different in the two detection phases A and B in one cycle, the sense threshold is set to 2.
This eliminates errors in converting the output waveform of the comparator 4 into a digital signal of 1°0°.

FIG. 5 shows an embodiment of the threshold value setting circuit 3' for the present invention. FROM 8 connected to a counter 5 that counts it by inputting the drive phase signal 7 for rotating magnetic field drive
sends a threshold level code to the DA converter 9. This allows the DA converter 9 to set a threshold value 10 suitable for each phase.
can be output.

FIG. 6 shows an embodiment of the threshold value setting circuit according to the present invention. This consists of a plurality of transistors 11 driven by the output of a decoder 15 connected to a counter 5, one terminal of which is connected to the collector, and the other terminal connected to a common terminal 10.
To! ! It is composed of a plurality of variable resistors 12 connected together, and a resistor 14 connected between the common terminal 10 and a power source 13, and outputs the potential of the common terminal 10. This means that when any of the outputs of the decoder 16 becomes high level, the transistor 11 connected to it is turned on, and the threshold value of the common terminal ]O is determined by the variable resistor 12 connected to its collector.

In this embodiment, since the output can be adjusted independently for each phase using the variable resistor 12, the FROM 8 shown in FIG. 5 is not required, and the adjustment is simple. Figure 6 KNPN)
Although this is an example using a transistor, a similar configuration can be made using a PNP transistor or a MOS transistor.

As described above, it can be seen that according to the present invention, it is possible to easily realize a bubble detection device that detects bubble signals in a plurality of phases of a rotating magnetic field with high reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional example of a bubble detection device, FIG. The figure is an explanatory diagram of the detection gravity multiplication according to the present invention, Fig. 5 is an explanatory diagram of one embodiment of the threshold value setting circuit according to the present invention, and Fig. 6 is an explanatory diagram of an embodiment of another threshold value setting circuit according to the present invention. It is a diagram. In the figure, 1.1'...bubble detection element, 2...
Amplifier, 3.3'-... Threshold power supply, 4... Comparator,
5...Counter, 6...■Restorer, 7.7'
...Phase signal, death...P (capital) M, 9...D-A
Converter, 10... Threshold output, ]1... Transistor, 12... Variable resistor, 13... Power supply, 14...
-Resistor, 15...Decoder, 21...Rotating magnetic field, 22, 42...Amplifier output, 23.43...Drive signal, 24.44...4°C restorer output, 25.4
5... Threshold m, 26.46... Comparator output, 61.
... Capacitor, 62... Switch. 1st Exit 6 zml '0''/''0'/' Tuguan 4 Old

Claims (1)

[Claims] A plurality of detection elements detecting 66 bubbles at different phases with respect to one rotating magnetic field, an amplifier commonly connected to the plurality of detection elements, and an folding signal that compares the output of the amplifier with a sense threshold. 1. A magnetic bubble detection device comprising a comparator that changes the sense threshold value for each bubble detection phase in synchronization with the rotating magnetic field.