JPH01245402A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To always control a recording current to the optimum value corresponding to the temperature of a magnetic recording medium by detecting the temperature of the medium or its vicinity and generating a coefficient output corresponding to the kind of the medium, and then, controlling the recording current based on the coefficient output. CONSTITUTION:A temperature detector 4 detects the temperature T of a magnetic recording medium 3 and the detected output of the detector 4 is inputted to a coefficient converter 5 where the detected output is converted into a coefficient KT corresponding to the kind of the medium 3. Based on the coefficient KT, the amplification degree of a recording amplifier 1 is controlled through a recording current control circuit 6. Therefore, a recording current (is) is controlled to the optimum value in corresponding to the temperature dependency of the coercive force of the recording medium 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording device such as a video tape recorder or a digital audio recorder.

(Prior Art) Conventionally, in magnetic recording devices such as video tape recorders (VTRs) and digital audio recorders (DATs), signals to be recorded are amplified by a recording amplifier and magnetic Coercive force H of recording medium at room temperature
Optimal recording current according to e (i opl or i op2
) through the recording head, recording is performed so that the signal level on the recording medium is maximized, and sufficient override characteristics are obtained.

Incidentally, the coercive force He of the magnetic recording medium changes depending on the temperature T, as shown in FIG. Therefore, taking as an example a medium with a coercive force He of BOOOe at a temperature of 20°C, the input/output characteristics and override characteristics when the temperature rises from TI to T2 as shown in Figure 8 are as follows: Translation is performed by 1 op3/i op2 according to the temperature coefficient. As a result, if the recording current remains set to iop2, the signal level on the magnetic recording medium will be low and the override level will be insufficient, causing problems such as increased cross-modulation distortion and unstable head tracking.

In order to solve such problems, a method of controlling the recording current according to the temperature of the magnetic recording medium is proposed, for example, in Japanese Patent Application Laid-open No. 60-1.
This is proposed in Japanese Patent No. 75292.

However, there are various types of magnetic recording media used in magnetic recording devices, and as shown in FIG.
The temperature coefficient ranges from positive to negative. Therefore, if a single coefficient is used to control the recording current, the recording current will be controlled in a direction away from the optimum value, which may have the opposite effect.

(Problem to be Solved by the Invention) In this method of controlling the recording current according to the temperature of the magnetic recording medium, it is difficult to control the recording current optimally when using media with different temperature coefficients of coercive force. The problem was that I couldn't do it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording device that can always maintain a recording current at an optimum value in response to changes in temperature of the medium, regardless of the type of magnetic recording medium.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a temperature sensor that generates a detection output of a temperature detector that detects the temperature of a magnetic recording medium or a temperature in the vicinity thereof, and a coefficient output that corresponds to the type of recording medium. A coefficient converter is provided, and the recording current supplied from the recording amplifier to the magnetic head is controlled by the coefficient output of the temperature coefficient converter.

Further, in the present invention, the temperature detector is preferably installed so as to detect the temperature of the magnetic recording medium at a portion that is in contact with the magnetic head.

(Function) In the present invention, the temperature change of the coercive force He(T) of the medium is measured by detecting the temperature T of the magnetic recording medium (or the temperature in the vicinity thereof) with a temperature detector, and the temperature coefficient converter The coercive force Hc(T) for each type of media is determined by
An output is generated representing a coefficient KT according to the temperature characteristic of . Based on this coefficient KT, the recording current is supplied from the recording amplifier to the magnetic head is always controlled to the optimum value.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram according to an embodiment of the present invention. A signal es to be recorded is amplified by a recording amplifier 1, and a recording current is is supplied from the recording amplifier 1 to a magnetic head 2. As a result, a signal is recorded on the magnetic recording medium 3 that runs at a certain relative speed with respect to the magnetic head 2.

The temperature detector 4 is configured using, for example, a thermistor, and detects the temperature T of the magnetic recording medium 3. The detection output of the temperature detector 4 is input to the coefficient converter 5, and is converted into an output according to the coefficient KT shown in the following equation according to the type of medium 3.

KT-f tape(T)-
(1) "tape" of the function f tape(T) in equation (1)
” indicates that it depends on the various magnetic recording media shown in FIG.

Expressing equation (1) as a function of coercive force He, KT o
c He tape(T)
−(2). Note that the relationship in equation (1) follows the temperature characteristics of coercive force shown in Figure 9, and as the temperature T
This can be easily obtained by A/D converting the detection output of and performing digital processing.

By controlling the amplification degree of the recording amplifier 1 via the recording current control circuit 6 based on the coefficient KT obtained in this way, the recording current is is determined by the temperature of the coercive force HC of the recording medium 3. Controlled to the optimum value according to dependence.

1s-f (es, KT) (X:KT es-
(3) To explain in detail with reference to FIG.
Assume that the medium has a positive temperature coefficient, such as a Ti-substituted Ba ferrite coating medium, and the temperature of this medium rises to T2. In this case, the coercive force increases according to the temperature characteristics of the coercive force of the Co-Ti substituted Ba ferrite shown in FIG. 9, and the input/output characteristics and override characteristics each move in parallel to the T2 position shown by the broken line in FIG. . The coefficient KT obtained by detecting the temperature of the iron, magnetic recording medium 3 changes (increases in this case) according to a function according to the temperature characteristics of the coercive force shown in FIG. According to equation (3), the recording current is increases from i op2 to i op3, and the eighth
As shown in the figure, the optimum recording conditions are always satisfied.

Next, another embodiment of the present invention will be described.

The embodiment shown in FIG. 2 is an example applied to a rotating head type magnetic recording device in which recording is performed on a magnetic recording medium 3 by a rotating magnetic head 2 provided on a head cylinder 8.
The temperature sensor 9 attached to the guide post 8 measures the temperature of the medium 3.
It is designed to detect the temperature of This embodiment can be realized by simply adding circuit parts such as the temperature detector 9 and the temperature coefficient converter 5, without making any special modifications to the mechanism of the conventional rotary head type magnetic recording apparatus.

The embodiment shown in FIG. 3 uses a non-contact type temperature detector 10, such as an infrared sensor, as the temperature detector in a rotary head type magnetic recording apparatus similar to that shown in FIG. According to this embodiment, the temperature of the magnetic recording medium 3 can be detected more accurately.

The embodiment shown in FIG. 4 is a rotary head type magnetic recording device similar to that shown in FIG. Using a non-contact temperature detector 10 such as a sensor, the sample/hold circuit 11 samples and holds the temperature of the magnetic recording medium 3 in accordance with the timing to when the magnetic head 2 passes, and this output T (to) is used as the temperature. It is designed to be supplied to the coefficient converter 5. Note that a sampling pulse is supplied to the sample/hold circuit 11 from the timing circuit 12 at the timing to when the magnetic head 2 passes in front of the temperature detector 10 . Therefore, according to this embodiment, recording can be performed with the optimum recording current based on the coercive force of the magnetic recording medium 3 during recording by the magnetic helad 2.

In the embodiment shown in FIG. 5, a temperature sensor 22 is integrated into a thin film magnetic herad 21. According to this embodiment, the temperature at the recording position of the magnetic recording medium 2.

Capable of detecting extremely close temperatures, making the system more compact.

It is also effective for simplification.

The embodiment shown in FIG. 6 is a magnetoresistive element (MR element) having a pattern as shown in FIG. 7 in the thin film magnetic herad 21.
A temperature detector 23 consisting of the following is integrally provided. The temperature detector 23 made of this MR element is supplied with current from a constant current source 24, and its voltage drop is supplied to the temperature coefficient converter 5 as a temperature detection output.

According to this embodiment, a reproducing magnetic head made of an MR element can be used as the temperature detector 23.

In this case, by using an MR element with a center tap as shown in Figure 7 and connecting it as shown in the figure, the effect of resistance change of the MR element due to the magnetic field is canceled out when detecting temperature, and the effect of resistance change due to temperature is canceled. Only resistance changes are detected. If the frequency component of the resistance change of the MR element due to the magnetic field and the frequency component of the resistance change of the MR element due to temperature are significantly different, the temperature detector should be an MR element with a center tap as shown in Figure 7. It does not have to be a simple shape.

In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[Effects of the Invention] According to the present invention, a temperature coefficient converter is provided that generates a detection output of a temperature detector that detects the temperature of a magnetic recording medium or a temperature in the vicinity thereof and a coefficient output according to the type of recording medium, By controlling the recording current based on the coefficient output of this temperature coefficient converter, it is possible to always control the recording current to the optimum value according to the temperature of the medium, even when using media with different coercive force temperature coefficients. can. Therefore, no matter what kind of magnetic recording medium is used, it is possible to increase the signal level on the medium, reduce cross-modulation distortion, and
Head tracking can be stabilized.

Additionally, if the temperature of the magnetic recording medium is detected, especially at the part of the magnetic recording medium that is in contact with the magnetic head, it becomes possible to perform recording with a recording current that corresponds to the coercive force of the medium during recording, which further optimizes the recording current. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording device according to one embodiment of the present invention, and FIGS. 2, 3, 4, 5, and 6 are main part configurations of other embodiments of the present invention. FIG. 7 is a diagram showing the configuration of the temperature detector used in the embodiment of FIG. 6, FIG. 8 is a diagram showing an example of the input/output characteristics and override characteristics of the magnetic recording medium, and FIG. FIG. 3 is a diagram showing the temperature characteristics of coercive force of various magnetic recording media. DESCRIPTION OF SYMBOLS 1... Recording amplifier, 2... Magnetic head, 3... Magnetic recording medium, 4... Temperature detector, 5... Temperature coefficient converter, 6... Recording current control circuit, 7... ··Cylinder,
8... Guide post, 9... Temperature detector, 10...
・Non-contact temperature detector, 11... Sample and hold circuit, 12... Timing circuit, 21... Thin film magnetic head, 22... Temperature detector, 23... Temperature consisting of magnetoresistive element. Detector, 24...constant current source. Applicant's agent Patent attorney Takehiko Suzue No. 1 Figure 2 Figure 3 Figure 4 Story side (Yuuuuu J$8 Figure Onsen T ('C) Figure 9

Claims (2)

[Claims] (1) A magnetic recording medium, a magnetic head for recording signals on the magnetic recording medium, a recording amplifier that supplies a recording current to the magnetic head according to the signal, and a temperature at or near the temperature of the recording medium. a temperature coefficient converter that generates a coefficient output according to the detection output of the temperature detector and the type of the recording medium; A magnetic recording device comprising: means for controlling a recording current supplied from the magnetic head to the magnetic head. (2) The magnetic recording device according to claim 1, wherein the temperature detector detects the temperature of a portion of the magnetic recording medium that is in contact with the magnetic head.