JPS588048B2 - Digital data storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of recording digital data on a magnetic medium, and is particularly effective for reading data from price tags on which data is recorded.

The price tag shown in Figure 1A is a tape mount 1 coated with a magnetic layer as a magnetic medium 2, or a commercially available magnetic tape pasted on which sales data such as product name and selling price are printed in digital binary format. After being magnetically recorded with a code, it is cut one by one, and the recorded surface is scanned by the tag reader 3 (playback head) shown in Figure 1B to read the data and input it to an electronic cash register, etc. It is used as a.

The recording surface of the magnetic medium 2 is divided into an area where data is magnetically written (this is referred to as a data recording area DS) and an area where nothing is written (this is referred to as a blank area ES). Conventionally, data is recorded in the data recording section according to the magnetization curve shown in A in FIG. 2 or A in FIG. 3, and the blank section is left unmagnetized.
(The data is expressed as "1001101").

When the recording surface of the magnetic medium obtained in this way is scanned by the tag reader 3 shown in 2 in Fig. 1, read signals as shown in B in Fig. 2 and B in Fig. 3 are obtained, but this method has the following drawbacks:

(1) The amplitudes of the first rise a and the last fall b of the waveform in FIG. 2B are so small that it is difficult to distinguish between noise and a reproduced signal.

This means that the first rise and the last fall correspond to the magnetic flux change from the non-magnetized point with zero magnetic flux density to the N pole and from the N pole to the non-magnetized point, respectively, and the magnetic flux change corresponds to the magnetic flux change from the N pole to the S pole. This is because it is half.

(2) In Figure 3B, the blank section (magnetized to the S pole)
When tag reader 3 is placed on
When the tag reader is not in contact with the recording surface) → Due to changes in the magnetic flux of the S pole, a falling pulse C shown in B is generated, and it is not possible to distinguish whether this is noise or a reproduced signal.

As mentioned above, a read signal that cannot be distinguished as noise or a reproduced signal causes a malfunction in the reproduction device (not shown).

The present invention eliminates the above drawbacks and provides a data recording method that allows correct data to be read by a tag reader or the like.

The present invention magnetically records data in a data recording section as usual, and records data in an adjacent blank section by gradually demagnetizing it outward from the end of the data recording section. As a result, as shown in the magnetization curve shown in Figure 4A, the magnetization gradually demagnetizes from the edge of the data recording section to the outside, and
The magnetic medium is magnetized in such a way that it becomes completely non-magnetized at the point and the Y point.

When this recording medium is scanned by the tag reader 3, the readout waveform shown in FIG. An amplitude sufficient to distinguish it from noise can be obtained.

In the blank sections d and e adjacent to this, level changes occur in the falling and rising edges of the waveform, respectively.
As shown in the figure, the magnetic flux change in the blank section is gradual, so
The level change in the readout waveform represented by the differential waveform is extremely small and will not be mistaken as a reproduction signal.

Next, the recording method of the present invention will be explained using a specific example.

5 and 6 are data write circuit diagrams of the first embodiment.

D is a write data signal, ER is a high level potential, ground is a low level potential, Q1 to Q3 are NPN transistors, H is a write head, S is a switch, and N is an inverter.

In both FIGS. 5 and 6, signals D and D are applied to the bases of transistors Q1 and Q2, respectively, via resistors, and a write current is supplied directly to the head H from each collector.

A resistor R and a capacitor C constitute an integrating circuit, and in Figure 5 this circuit is connected to the collectors of transistors Q1 and Q2, and in Figure 6, the emitters of transistors Q1 and Q2 are connected in common and a new circuit is connected to this circuit. A transistor Q3 is connected to the base of the transistor Q3, and the above-mentioned integrating circuit is provided at the base of the transistor Q3.

When recording using the circuit shown in FIG. 5, the process is as follows.

Since the signal D is at a low level in the blank section, the transistor Q
The bases of 1 and Q2 are high level and low level respectively.

When switch S is closed, voltage is gradually applied to the collectors of transistors Q1 and Q2 by the above-mentioned integrating circuit, and Q
1 and Q2 go in the direction of conduction and cutoff, respectively.

The current in the direction of the arrow in the head H gradually increases, and the recording medium is gradually magnetized in the direction of the south pole from point X, as shown in FIG. 4A.

Next, when the collector current of the transistor Q1 is saturated, the data recording section begins, and the signal D repeats high and low levels depending on the data content, changing the current direction of the head H.
A magnetic medium is magnetized to the north and south poles.

When switch S is opened in the blank section after the end of this data section, the current supplied to the collectors of transistors Q1 and Q2 is
It is provided by capacitor C and gradually decreases.

Along with this, the current in the head H also decreases, and the magnetic medium is gradually magnetized in the direction of non-magnetization from the end of the data section, as shown in FIG. 4A, and completely reaches the non-magnetization point at point Y.

When recording using the circuit shown in FIG. 6, the process is as follows.

In the first blank section, the bases of transistors Q1 and Q2 are at high level and low level, respectively, similar to the circuit in Figure 5, and when switch S is closed, the connection point between resistor R and capacitor C gradually becomes high level. Therefore, transistor Q3 is gradually turned on, and a voltage is applied between the collectors and emitters of transistors Q1 and Q2.

The current of the head H in the direction of the arrow gradually increases, and after this current becomes constant, the direction of this current is changed according to the content of the data signal D, and data is written.

After this data period, the switch S is opened and the base current of the transistor Q3 is supplied only from the capacitor C and gradually decreases.

Therefore, the change in the current flowing through the head H is the same as in the case of FIG. 5, and the recording medium is similarly magnetized as shown in FIG. 4A.

The first embodiment shown in FIGS. 5 and 6 shows a method in which data sections and blank sections are continuously written using one write head.

Next, a second embodiment will be described.

In Figure 7, H1 is a write head, H2 is an erase head, and C1
is a write circuit, C2 is an erase circuit, 2 is a magnetic medium on the tape-shaped mount 1, L is a light source, P is a photodetector, D is a data signal, CN is a control signal, AM is a position detection circuit, and PS is a detection signal. It is.

FIG. 8 shows a tape-shaped mount 1, a magnetic medium 2 attached thereto, and each section of data recorded thereon.

In FIG. 7, head H1 is a head that writes a data signal in a data section, and H2- is an erase head that operates in a blank section.

The magnetic medium 2 is tape-shaped as shown in FIG. 8, and is moved continuously in the direction of the arrow in FIG.
Writing or erasing is performed with and H2.

The circuit AM detects the position of the mount 1 between the light source L and the detector P, and generates a signal PS based on changes in the light received by the detector P.

To explain the operation, first, a blank section is magnetized to either the N pole or the S pole using the head H1, and data is written in the data section in the same manner as before.

In other words, it is magnetized as shown in FIG. 3A.

Next, an alternating current magnetic field is gradually applied to the blank section of the magnetic medium using the head H2 to make it magnetized in the shape shown in FIG. 4A.

In addition, when the head H2 is located at a certain distance from the end of the data section, it is also possible to suddenly generate an alternating magnetic field from this head.

In this case, the farther away from the head H2 the less magnetism is erased, resulting in magnetization as shown in FIG. 4A.

As can be seen from the above, FIG. 7 shows a writing method using two heads, one for writing and one for erasing.

As shown in FIG. 8, the magnetic medium thus obtained includes a gradually decreasing/increasingly magnetized region GS and a completely non-magnetized region NS in the blank section ES.

As is clear from the above explanation, in the data writing method according to the present invention, the magnetization level of the section where data is not written (blank section) of the magnetic medium is the section where data is written (blank section).
It is characterized by magnetization that gradually decreases outward from both ends of the data writing section (data writing section), and when the recording surface of a magnetic medium written in this way is scanned with a reading head such as a tag reader, it will not work as before. The read signal does not contain pulses that cannot be distinguished as noise or reproduction signals, and malfunctions of the reproduction device can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the price tag and tag reader operation, Figs. 2 and 3 are diagrams of the magnetization curve of the recording surface and its readout signal waveform by the conventional method, and Fig. 4 is the magnetization curve of the recording surface and its readout according to the present invention. Signal waveform diagrams, Figures 5 and 6 are diagrams for explaining the first embodiment of the present invention, Figure 7 is a diagram for explaining the second embodiment of the present invention, and Figure 8 is a diagram for explaining the tape-shaped price tag recorded according to the present invention. It is an explanatory diagram. H, Hl...Writing head, H2...
Extinguishing head, S... Switch, C, R...
...Integrator circuit.

Claims (1)

[Claims] 1. A step of magnetically recording digital data on a magnetic recording medium with the magnetization level of either N pole or S pole at both ends of the data recording section, and adding magnetization at both ends to blank areas adjacent to both sides of the data recording section. forming a demagnetized section from a level to a non-magnetized level.