JP2615928B2 - Data reader - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a recording medium on which a plurality of data are magnetically recorded with a recording width corresponding to the reading direction, in the reading direction and relative to the recording medium. The present invention relates to a data reading device including a reading magnetic head that outputs a reading signal having a peak interval corresponding to each data by scanning and moving.

FIG. 3 is a circuit diagram of a conventional data reading apparatus. In FIG. 3, reference numeral 2 denotes the whole of a conventional data reading apparatus. Reference numeral 4 denotes a recording medium on which a plurality of data are magnetically recorded with a recording width corresponding to the reading direction. Reference numeral 6 denotes a scanning medium which moves on the recording medium 4 in the reading direction and relatively to the recording medium 4. A read magnetic head for outputting a read signal S1 having a peak interval corresponding to each data, 8 is an amplifier for amplifying and outputting the read signal S1, and 10 is a read signal S1 from the amplifier 8.
A differentiation circuit consisting of a capacitor C and a resistor R for differentiating
A data output circuit 12 comprises an amplifier 14 and a buffer 16 and forms a digital waveform of the differentiated output of the differentiating circuit 10 and outputs this as a data signal S2. 18 is connected to the amplifier 8 and controls the level of the read signal S1. An error detection circuit that detects and outputs a level error detection signal S3 when the level of the read signal S1 is equal to or lower than a specified value L2.

In the conventional data reading device 2 having the above configuration, as described with reference to the timing chart of FIG. 4, the data from the magnetic head 6 amplified by the amplifier 8 at each of the times t0 and t1. When the read signal S1 (see FIG. 4 (a)) reaches the peak points P0 and P1, respectively, the data output circuit 12 outputs a data signal S2 [FIG. b) is output. Similarly, when the read signal S1 from the magnetic head 6 reaches the peak points P1 and P2 at the times t1 and t2, the data output circuit 12 outputs the signals from the times t1 to t2.
The data signal S2 which becomes low level during t2 is output. In this way, when the read signal S1 reaches the peak points P2 to P7 at times t2 to t7, respectively, the data output circuit
From 12, each of the high-level and low-level data signals S2 is shaped and output.

In this manner, the data output circuit 12 outputs the read signal S1 formed by digital waveform shaping.
In this case, the read signal S1 read by the magnetic head 6
Is a fixed time interval T for data of "0".
However, at least one peak point exists during the fixed time interval T for the data of "1". That is, in the case of data of “0”, the time t0
There are no peak points between t1, t1 to t2, t2 to t3, t3 to t4, and t6 to t7. On the other hand, in the case of the data of "1", there is one peak point between times t4 and t6.

Therefore, it is possible to read data based on the data signal S2 by determining whether or not the waveform of the data signal S2 output from the data output circuit 12 changes within the predetermined time interval T by a later-described determination circuit (not shown). it can.

In this case, if the peak point level of the read signal S1 from the magnetic head 6 fluctuates, the data cannot be read accurately, so that the read signal S1
Is detected by the error detection circuit 18. That is, when the peak point level is, for example, the peak point P3 is lower than the peak point level L1 of the other peak points.
When it becomes L2 (see time t3 in FIG. 4A), the error detection circuit 18 outputs a high-level error detection signal S3 (see FIG. 4D) when the level of the peak point P3 is detected. Thereby, a processing corresponding to the error can be performed by a processing circuit (not shown) at a subsequent stage.

By the way, in such a data reading device 2, since the differentiating circuit 10 is used for peak point detection, the S / N ratio does not increase. Therefore, for example, the pseudo peak point P2 'is affected by noise.
When [time t2 'in FIG. 4 (a)] occurs, an abnormal read signal S2' due to the pseudo peak point P2 '[time in FIG. 4 (c)] is generated instead of the normal read signal S1. t
2 ′] is output from the data output circuit 12.

If such an abnormal read signal S2 'is output, data cannot be read correctly. That is, as shown in FIG.
In the case of S2, data that should be "0" at time t2 to t3 is read as "1" data at the same time as shown in FIG. 4 (c). In addition, since the error detection circuit 18 has a circuit configuration independent of the data output circuit 12 and is in a state where synchronization is not established with each other, a level error as shown at time t3 in FIG. However, since it is unknown at what timing the level error has occurred, it is impossible to perform data correction corresponding to the level error.

(Object of the Invention) The present invention has been made in view of such circumstances, and data is normally read even if a pseudo peak point due to noise occurs in a read signal in addition to an original peak point. This means that even if the read signal has a different level from the specified level or there is a level error, it is possible to accurately determine when the level error occurred. The purpose is to enable data correction corresponding to the level error by making it possible to determine.

(Structure and Effect of the Invention) In order to achieve such an object, in the data reading device of the present invention, the data reading device reads the data on a recording medium on which a plurality of data are magnetically recorded with a recording width corresponding to the reading direction. A read magnetic head that outputs a read signal having a peak interval corresponding to each data by scanning and moving in the direction and relative to the recording medium, an amplifier that amplifies the read signal, and an amplifier that is amplified by the amplifier. An A / D converter that converts the read signal into an A / D signal each time a sampling clock having a period shorter than the peak interval of the read signal is input, and outputs the A / D conversion output as quantized data. Means for detecting the peak data of the quantized data from the quantized data output from the A / D converter; and A counter for counting and outputting the time interval of each of the peak data, and data determining means for determining the data output from the peak data detecting means based on the count output of the counter.

In the above configuration, the magnetic head is moved by scanning over a recording medium on which a plurality of data are magnetically recorded with a recording width corresponding to each of the reading directions. Along with this scanning movement, the magnetic head magnetically reads a plurality of data recorded in the reading direction, and uses the reading as a reading signal via an amplifier.
Output to A / D converter.

The A / D converter A / D converts the read signal amplified by the amplifier for each input of a sampling clock having a cycle shorter than the peak interval of the read signal, and uses the A / D converted output as quantized data. Output. The peak data detecting means detects peak data of the quantized data from the quantized data output from the A / D converter. The counter counts and outputs the time interval of each peak data based on the output of the peak data detecting means. The data determination means determines data output from the peak data detection means from the count output of the counter.

Therefore, according to the present invention, even if a pseudo peak point exists in the waveform of the read signal due to noise in addition to the original peak point, the pseudo peak point is smaller than the original peak point, so that A / D Since the pseudo peak point does not appear in the quantized data from the converter, the peak data representing the peak point interval output from the peak data detection means corresponds exactly to the peak point of the read signal. As a result, the determining means for determining data based on the output of the counter and from the peak data from the peak data detecting means can accurately determine the data included in the read signal. Similarly, when the level of the read signal fluctuates in a direction smaller than the prescribed level, the generation timing of the peak data in the quantized data of the A / D converter can be determined by the determination means, so that the data corresponding to the level error can be determined. Corrections can be made.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of a data reading device according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those shown in FIG. 3 according to the conventional example indicate the same components and parts as those indicated by the reference numerals also in this embodiment. Unless otherwise specified, the present embodiment and the conventional example also have the same configuration regarding the connection relationship and the like.

In this embodiment, the configuration different from the conventional example is as follows.

That is, the data reading device of the present embodiment A / D-converts the read signal S1 amplified by the amplifier 8 every time a sampling clock S4 having a cycle shorter than the peak interval of the read signal S1 is input. An A / D converter 22 that outputs a D-converted output as quantized data S5, and an A / D converter 22
From the quantized data S5 output from the
Peak data detecting means 24 for detecting the peak data S6 of
A counter that resets and starts counting each time the output of the peak data detecting means 24 is input, and counts and outputs the time interval T of each peak data S6 from the start to the input of the next output. 26 and this counter 26
And data judging means 28 for judging the data S6 output from the peak data detecting means 24 from the count output S7.

In this case, the peak data detecting means 24 and the counter 26
And the data determination means 28 can be configured in hardware, but these are configured with a CPU and the CPU is
It is also possible to adopt a software configuration in which the operation is controlled according to the program described above, and the quantized data of the A / D converter 22 is stored in the RAM and used for data reexamination later.

The other configuration is the same as that of the conventional example, and the description is omitted.

Next, the operation of the data reading apparatus of this embodiment will be described with reference to the timing chart of FIG.

That is, the read signal S1 having the waveform shown in FIG. 2A is input to the input unit IN of the A / D converter 22. A / D
The sampling clock S4 shown in FIG. 2B is input to the clock input section CLK of the converter 22. The A / D converter 22 outputs the read signal S1 for each input of the sampling clock S4.
A / D conversion and the A / D conversion output are shown in Fig. 2 (c).
Is output as quantized data S5 as shown in FIG. The operation of A / D converting the read signal S1 in FIG. 2A with the sampling clock S4 in FIG. 2B and outputting it as the quantized data S5 in FIG. 2C is well known. Although the detailed explanation is omitted here, the point is that each peak point of the read signal S1 is
P1 to P7 are the respective peak points Q1 to Q7 of the quantized data S5.
(▽ in the figure). In this case, since the pseudo peak point P2 'does not appear as a peak point in the quantized data S5 from the A / D converter 22, no data reading error occurs due to the pseudo peak point P2'. Further, among the peak points of the read signal S1, the peak point of the quantized data S5 corresponding to the level P3 smaller than the specified level is Q3, and the generation timing of the Q3 is searched from the peak data of the quantized data S5. Therefore, even if a level error has occurred, the level error can be accurately detected and a level correction corresponding to the level error can be performed.

In this manner, the data reading apparatus of the present embodiment can normally read data even if a pseudo peak point due to noise occurs in the read signal in addition to the original peak point. Even if there is any level error that is high in noise and there is a level different from the specified level in the read signal, it is possible to accurately determine at which timing the level error occurred It is possible to perform data correction corresponding to the level error.

[Brief description of the drawings]

1 and 2 relate to an embodiment of the present invention, FIG. 1 is a circuit diagram of a data reading apparatus according to the embodiment, and FIG. 2 is a timing chart for explaining the operation. 3 and 4 relate to a conventional example, FIG. 3 is a circuit diagram of a data reading device according to the conventional example, and FIG. 4 is a timing chart for explaining the operation. 4 recording medium, 4 magnetic head, 8 amplifier, 22
…… A / D converter, 24 …… Peak data detection means, 26 ……
Counter, 28... Determination means.

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein a plurality of data are magnetically recorded in a recording width corresponding to the reading direction, and the data is scanned and moved in the reading direction relative to the recording medium. A read magnetic head that outputs a read signal having a peak interval; an amplifier that amplifies the read signal; and a sampling clock having a period shorter than the peak interval of the read signal. A / D converter and an A / D converter that outputs the A / D conversion output as quantized data, and peak data of the quantized data from the quantized data output from the A / D converter. Means for detecting; a counter for counting and outputting a time interval of each of the peak data based on an output of the peak data detecting means; Data reading apparatus characterized by comprising a data determination means from the count output of the printer performs the determination of the data output from the peak data detecting means.