JPH01245406A - Overwrite characteristic improvement circuit - Google Patents

Abstract

PURPOSE:To prevent deterioration of the overwrite characteristics of a recording medium by changing the write current of a read/write head for writing on the recording medium in accordance with the ambient temperature and controlling the temperature characteristics of the magnetic flux density of the read/ write head. CONSTITUTION:The write current 10 of a read/write head 6 for writing on a recording medium 13 is changed in accordance with the ambient temperature and the temperature characteristics of the magnetic flux density of the read/ write head 6. In other words, the temperature characteristics of the voltage of a voltage source 9 is controlled so that the writing (recording) depth 20 in the length direction of the recording medium 13 can become the same as the previous writing depth 21 irrespectively of a change in coercive force of the recording medium 13 due to the temperature characteristics. Therefore, deterioration of the overwrite characteristics can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates particularly to improving the reliability of data storage devices used in computer equipment.

[Prior Art] FIG. 4 is a circuit diagram showing a write circuit of a conventional data storage device disclosed, for example, in "Latest Floppy Disk Devices and Their Application Know-how J" written by Shoji Takahashi and published by CQ Publishing. , 3 is a write current setting resistor, 4 is a write current setting circuit that sets the write current 7 by the current flowing through the write current setting resistor 3, and 5 is a write current 10 set in the write current setting circuit 4. /W
(Read/Write) This is a write driver that flows to the head 6.

FIG. 5 is an explanatory diagram showing the writing depth of the recording medium by the R/W head of FIG. 4. In the figure, 12 is a gap portion of the R/W head 6, and 13 is a recording medium.

Next, the operation of the write circuit of the conventional data storage device will be described. The write current setting circuit 4 sets the value of the write current 10 based on the current flowing through the write current setting resistor 3, and causes the write current 10 to flow through the R/W head 6 via the write driver 5 during writing. This write current 10 generates a magnetic field with a magnetic flux density Bs in the gap portion 12 of the R/W head 6 shown in FIG. At this time, the recording medium 13
Let Hc be the coercive force of the gap portion 12 of the R/W head 6.
If the gap length is g, then the recording depth D of the recording medium 13 is
can be approximated by the following equation.

Considering that the overwrite characteristics are caused by the longitudinal recording depth DL, and in order to obtain the temperature characteristics, the above equation (2) is differentiated with respect to the temperature T, resulting in the following equation.

Here, the temperature coefficient of coercive force He and magnetic flux density BS is △Hc
, ΔBs, Ha and Bs are expressed as shown below.

Hc = HcoX (1+ΔHCX T )Bs”
EISOx (1+ΔBs XT) However, Hco +
B So is Hc at T=O°C.

This is the value of Bs. As a result, the right end of the above equation (3) is approximated as shown in the following equation.

Therefore, the temperature change in the recording depth D is proportional to the temperature coefficient ΔBs of the magnetic flux density BS of the R/W head 6 minus the temperature coefficient ΔHc of the coercive force Hc of the recording medium 130. 13 with C9-γ-Fe20. If ferrite is used for the R/W head 6, the above (ΔB8−ΔH
c) is a negative value, and if the R/W head 6 is used to write on the recording medium 13 at a low temperature and then overwritten at a high temperature, an unerased area will be generated, resulting in poor overwriting characteristics. Become.

[Problems to be Solved by the Invention] Since the write circuit of the conventional data storage device is configured as described above, the write circuit of the R/W head 6 and the recording medium 13 can be combined. Temperature coefficient ΔBs of magnetic flux density Bs and temperature coefficient Δ of coercive force Hc of recording medium 13
It is necessary to reduce the difference between Hc and ΔB, and 8H.
There were problems such as the need to avoid deterioration of overwrite characteristics due to the difference between .

This invention has been made to solve the above-mentioned problems, and provides an overwrite characteristic improvement circuit that controls to reduce the difference between ΔBS and ΔHc and prevents deterioration of overwrite characteristics. With the goal.

[Means for Solving the Problems] The overwrite characteristic improvement circuit according to the present invention changes the write current recorded by the R/W head on the recording medium depending on the ambient temperature, and changes the temperature of the magnetic flux density of the R/W head. The characteristics are controlled.

[Function] The overwrite characteristic improvement circuit according to the present invention has a circuit that changes the write current for recording on the recording medium by the R/W head depending on the ambient temperature and maintains the writing depth of the recording medium constant. To improve overwrite characteristics due to temperature dependence of magnetic flux density of an R/W head.

[Embodiment] Fig. 1 is a circuit diagram showing an overwrite characteristic improvement circuit used in a data recording device which is an embodiment of the present invention, and Fig. 2 shows the writing depth of a recording medium by the R/W head of Fig. 1. FIGS. 3(a) and 3(b) are diagrams showing waveforms reproduced by the R/W head in a conventional example and an embodiment of the present invention. In the figure, 1 is a temperature-sensitive resistor, 2 is a current buffer using an emitter follower type transistor, and 3 is a current buffer using an emitter follower type transistor.
4 is a write current setting resistor, 4 is a write current setting circuit that sets the write current 7 by the current flowing through the write current setting resistor 3, and 5 is a write current setting circuit that causes the write current 10 set in the write current setting circuit 4 to flow to the R/W head 6. It is a light driver. Reference numeral 8 denotes a bias resistor for applying a bias current to the temperature-sensitive resistor 1, and the bias resistor 8, the temperature-sensitive resistor 1, and the current buffer 2 constitute a voltage source 9. 11 is an extra pulse in the reproduction waveform by the R/W head 6, 13 is the recording medium, and 20.21 is the writing depth and previous history writing depth of the recording medium 13 by the R/W head 6.

In the overwrite characteristic improvement circuit according to the present invention,
The temperature characteristics of the voltage in the voltage source 9 are shown in FIG. The writing depth 20 of the recording medium 13 and the previous history writing depth 21 shown in FIG. 1 are set to be constant. In other words, in order to keep the value in the parentheses on the right side of the above (2) constant, Δ
Set to give a ΔBS change of π/2 of I(o.

As described above, by keeping the writing depth 20 of the recording medium 13 shown in FIG. 2 the same as the previous history writing depth 21, the unerased portion of the previous history is suppressed to a low level. Therefore, in the waveform reproduced by the R/W radar 6 shown in FIG. 3(a), it is possible to prevent the generation of extra pulses 11 due to noise caused by the unerased portion of the previous history. ) It is possible to obtain a reproduced waveform with clean characteristics and no extra pulse 11 as shown in FIG.

In addition, although the above embodiment describes the case where the longitudinal writing depth of the recording medium 13 is made constant, it can also be applied to the vertical writing depth of a recording medium using B,-ferrite. It has the same effect as.

C Effects of the Invention] As described above, according to the overwrite characteristic improvement circuit of the present invention, the write current for recording on the recording medium by the R and /W heads is changed depending on the ambient temperature, and the magnetic flux density of the R/W head is changed. Since it is configured to control the temperature characteristics of the recording medium, it is possible to maintain a constant writing depth of the recording medium, which has the excellent effect of providing a high-performance data storage device with improved overwrite characteristics at a low cost. It is something that plays.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an overwrite characteristic improvement circuit used in a data storage device which is an embodiment of the present invention, and FIG. 2 is an explanation showing the writing depth of a recording medium by the R/W head of FIG. 1. 3(a) and (b) are diagrams showing reproduction waveforms by the R and /W heads in the case of a conventional example and an embodiment of the present invention, and FIG. 4 is a diagram showing a write circuit of a conventional data storage device. The circuit diagram shown in FIG. 5 is an explanatory diagram showing the writing depth of the recording medium by the R/W head of FIG.・Write current setting resistor, 4...Write current setting circuit, 5.
...Light driver, 6. ,, R/W head, 7...
Write current, 8...bias resistance, 9...voltage source,
11... Extra pulse, 12... Gap part,
13... Recording medium, 20... Writing depth, 21...
・This is the depth of previous history writing. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Embedded by Masuo Oiwa 2nd figure 6: R/w to,,to' 13: Yoshiki recording medium 20: (Payment h5 Mayuzumigo 21: Night history number 311 (G) b) 11: Extra driver 0's Figure 5 6: To R/w, Rad 12: Gear 1.2 bu Guo 13: Yoshido (Takashi IL< enumerated,

Claims (1)

[Claims] In a data storage device that uses a recording medium to rewrite information by overwriting, the write current is changed based on temperature changes corresponding to the temperature characteristics of the coercive force of the recording medium depending on the ambient temperature, and the writing depth of the recording medium is changed. An overwrite characteristic improvement circuit characterized by comprising a circuit that maintains the overwrite characteristic constant.