JPS60150272A - Information reproducing circuit of magnetic tape - Google Patents

Abstract

PURPOSE:To improve the overall performance by switching the filter band of a data reproducing circuit to each suited one between the write and read modes. CONSTITUTION:In a read-after-write mode a write status signal (3) is supplied to a differentiation circuit (DiF) 6 which detects the peak position of the data signal read by a reading head 3. A gate part 10 sets transistors (TR) Q1 and Q2 under a nonconductive state and contains only resistances R1 and R2. In a read mode no signal (3) is supplied to the part 10 and therefore both TRs Q1 and Q2 conduct. At the same time, resistances R3 and R5 are connected in parallel to R1 and R2. The output of a frequency FO is automatically controlled at a digital gain control amplifier 11 according to an automatic gain control area. Therefore a reading band (2)' has larger width than a writing band (1)' in terms of the overall characteristics for the combination output of an LPF7 with the circuit DiF6.

Description

Detailed Description of the Invention (a) Technical Field of the Invention □ The present invention has a door-after-write function in which, when information is written, information written in parallel by adjacent reading heads is checked. The present invention relates to a magnetic tape device, and particularly relates to an information reproducing i-path of a magnetic tape device that switches the characteristics of a band-limiting filter when writing information and when reading information.

(b) Technical Background Read-after-write function (When information is written by an implantation head, it is read in parallel by an adjacent reading head to check whether it was written correctly.)
In the information reproducing circuit of a magnetic tape device having a read-after write, the band-limiting filter circuit (hereinafter simply referred to as a filter circuit) used during read-after-write is the same as the filter circuit used during reading. However, the characteristics of the filter circuit and the characteristics of the filter circuit required for reading are generally different.

In reality, the actual situation is that the overall performance is degraded because we have to adjust to one characteristic or take a middle point between the two.

As the use of information processing systems becomes more complex and sophisticated, magnetic tape devices are widely used as external auxiliary storage devices for information processing, so there is a demand for the development of magnetic tape devices with higher performance functions.

(C) Problems with conventional technology Next, a conventional information reproducing circuit for a magnetic tape device will be explained with reference to the drawings.

FIG. 1 shows an information reproducing circuit of a conventional magnetic tape device.

- In the figure, 1 is a magnetic tape, 2 is a write head, 3 is a read head, 4 is a write circuit, 5 is an information reproducing circuit, 6
7 represents a differential circuit (hereinafter referred to as 1iF), 7 represents a low-pass filter (hereinafter referred to as LPF), and 8 represents a data determination circuit.

FIG. 1 shows a magnetic tape 1 for magnetically storing data, a write head 2 for magnetically recording data on the magnetic tape 1.
a read head 3 for reading stored data on the magnetic tape 1; A write circuit 4 provides a write data signal to the write head 2. an information reproducing circuit 5 for electrically reproducing the data signal read by the reading head 3; DiF 6. which is located in the information reproducing circuit 5 and detects the peak position of the read reproduction signal. LPF7 to remove noise. It is comprised of a data determination circuit 8 that returns the read signal as reproduction information.

When data is written by the write head 2, simultaneous writing and reproduction is performed in which the read head 3 checks whether there is any abnormality in the written data. At this time.

Noise (feedthrough) from the write head 2 is transmitted to the read head 3, and if this noise is large, it can cause data reproduction errors.
It is necessary to narrow the filter characteristics (combined filter characteristics of F7) to reduce the noise.

On the other hand, when reading data, the writing speed fluctuation during writing and the reading speed fluctuation during reading are superimposed, so the frequency component of the reproduced data includes a higher frequency component than the writing frequency. Therefore, it may be necessary to adjust the filter band to be wider than when writing.

For example, GCR method (one of the modulation methods of magnetic recording,
FO is the writing frequency when writing at 9042PCI (PCI is a unit of recording density representing the number of magnetization reversals per inch), and the fluctuation during writing is , assuming that the fluctuation during reading is 25%, the worst frequency of the reproduced data is FOX 1.25 x 1.25 = 1.6F
It becomes O.

As mentioned above, the filter bands of the information reproducing circuit 5 are contradictory when writing data and when reading data, but conventionally the filter band is set to either one or the other, or the filter band is set at the midpoint between the two. This had the disadvantage of causing an overall drop in performance.

(d) Object of the Invention The present invention has the following objects: 1. to provide a new magnetic tape device that eliminates the above-mentioned drawbacks; In short, the overall performance is improved by switching the filter band settings of the regeneration circuit to the filter bands passed respectively during writing and reading. The object of the present invention is to realize a magnetic tape device that can perform the following functions.

(e) Structure of the Invention The present invention provides a magnetic tape device that has a function of, when information is written by a write head, read in parallel by an adjacent read head and check whether the information has been written correctly. This is achieved by an information reproducing circuit for a magnetic tape device, which is an information circuit and is equipped with a switching means for switching the band-limiting filter characteristics used when writing information and when reading information, thereby improving overall performance. You can.

(f) Implementation of the invention 111j The present invention will be explained below with reference to the drawings.

FIG. 2 shows an embodiment of the information reproducing circuit of the magnetic tape device according to the present invention, in which (A) shows a circuit configuration diagram, and (B) and (C) show filter characteristic diagrams, respectively.

In the figure, 9 is an amplifier section, 10 is a gate section, and 11 is a digital gain control amplifier section (hereinafter referred to as IIGC-A).
(abbreviated as MP section).

The same symbols as in Fig. 1 indicate the same contents, and ■.

■' is the filter characteristic curve when writing, ■, ■' is the filter characteristic curve when reading, ■ is the write status signal, ■
is the gain control signal, CI and C2 are the capacitors, Ql and 02 are the transistors, FO is the write frequency, and R1-R6 are the resistors, respectively.

This embodiment uses a read head 3 for reading data written on a magnetic tape 1. DiF6. detects the peak position of the data signal read by the read head 3. LPF to remove noise from read data signal 7. An amplification section 9 that constitutes the DiF 6 and performs a signal amplification function. A gate section 10 that constitutes the HPF 6 and outputs a signal for switching filter characteristics. DGC-AMP section 11 that can vary the gain, transistors that increase and decrease the component values of the filter function section of DiF6 (differentiating circuit composed of resistors and capacitors), Q2, Di
Resistors R1, R2, which constitute the filter function part of F6
R3, R5, capacitors C1, C2, old transistors,
(It is composed of 12 bias resistors R4 and R6.

This embodiment lowers the cutoff frequency as shown in the filter characteristic curve ■ when writing data, and increases the cutoff frequency as shown in the filter characteristic curve ■ when reading data. This is an example in which data is reproduced using the following methods.

In other words, during read-after-write, the write status signal ■
is input to the gate section 10. Due to this.

The gate section 10 operates to turn the transistor Q2, which had been in a conductive state until then, into a non-conductive state.

By turning off transistors Ql and Q2, resistors R3 and R5 become resistors 1?1, l? 2, only the resistors R1 and R2 are used, and the filter operates as DiF6, which shows the filter characteristic curve ■.

On the other hand, when reading, the write status signal ■ is at the gate section 1.
Since the input voltage is not 0, the transistor L port 2 becomes conductive, and the resistors R3 and R5 are connected in parallel with the resistors R1 and R2, thereby operating as a DiF6 showing the filter characteristic curve .

In the GCR method, the DGC-^RA unit 11
Since the output at the frequency FO is automatically adjusted by the (automatic gain control area), the combined output of DiF6 and LPF7 is as shown in Figure 2 (C), and the characteristic reading band is the writing band. ■'You can get something wider.

In addition, as other embodiments, the constituent elements of LPF7 (resistance,
capacitor) as the write status signal in the same way as in the example above.
to change the filter characteristic curve ■′ when writing data.
It is also possible to implement a method in which the filter operates so as to show the filter characteristic curve ``■'' when reading data.

(g) Effects of the Invention According to the present invention as described above, information of a magnetic tape device is provided in which the filter band of the information reproducing circuit is optimally set for each of data writing and data reading, thereby improving the overall performance. This has the effect of providing a regeneration circuit.

[Brief explanation of drawings]

Figure 1 shows an information reproducing circuit of a conventional magnetic tape device. FIG. 2 shows an embodiment of an information reproducing circuit of a magnetic tape device according to the present invention. In the figure, 1 is a magnetic tape, 2 is a write head, 3 is a read head, 4 is a write circuit, 5 is an information reproducing circuit, and 6
7 is a DiF, 7 is an LPP, 8 is a data determination circuit, 9 is an amplifier section, 10 is a gate section, and 11 is a DGC-AMP section.

Claims (1)

[Claims] An information reproducing circuit for a magnetic tape device having a function of checking whether or not information has been written correctly by simultaneously reading information using an adjacent read head 1' when information is written using a write head 1', When writing information, love! l! An information reproducing circuit for a magnetic tape device, comprising a switching means for switching band-limiting filter characteristics used during reading.