JPS6350902A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To constitute a crosstalk reducing which between heads of a monolithic IC, by providing a positive voltage bias at the primary side of a transformer whose secondary side is connected to a magnetic head, and producing low impedance. CONSTITUTION:One end of a primary side of a rotary transformer 14 whose secondary sides are connected to corresponding magnetic head 15 respectively, is earthed, and the other end is connected to a recording amplifier 10 through a resistor 13, and a capacitor C1, and a recording signal voltage closes a switch with a timing corresponding to the head, then is impressed on the head 15. Also, the primary side of the transformer 14 is connected to a bias power source 16 having considerably small AC impedance via the crosstalk reducing switch SW12 among plural heads through a capacitor C2. While the SW12 is turned on, the C2 is charged, and a voltage goes to the one equivalent to the bias voltage 16. While the SW12 is turned off,a signal is superimposed centering a bias keeping the potential. Therefore, the terminal of the monolithic IC100 is always set at a positive potential, and a normal wave can be obtained without being affected by an incidental diode between the collector of the IC and a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic recording device compatible with multi-heads of, for example, a VTR, and has a means for reducing crosstalk between heads in a simple structure on a monolithic IC. related to things.

[Conventional technology]

FIG. 4 shows a conventional magnetic recording device, in which 10
is a recording amplifier; 11 is a switch (recording signal application means);
12 is a switch, 13 is a current limiting resistor, 14 is a low retransistor, 20 is a drum, 15 is a head, 21 is a magnetic tape, and C, CZ are capacitors.

In a multi-head magnetic recording device that uses a small drum wound at 270°, unused heads must have low impedance by shorting both sides of the transformer in order to reduce crosstalk between the heads. It won't happen.

FIG. 4 shows the case where one of the four heads records on the tape. In this case, the switch 11 is turned on and the switch 12 is turned off, and the signal from the recording amplifier 10 is transmitted to the head 15. is applied to. Conversely, when another head is working, switch 11 is set to 0FFL and switch 12 is turned on to make the transformer a low impedance to avoid crosstalk from the transformer.

[Problem that the invention seeks to solve]

Conventionally, the switch 12 was composed of an external discrete transistor 12a, as shown in FIG. 5, which grounded one end of the rotary transformer. However, the conventional circuit is still monolithic IC.
However, when trying to record a signal, the NPN I-transistor of the switch 12 has the disadvantage that the diode 103 between the substrate and the collector is turned on in the negative half cycle, as shown in FIG. 6, so the waveform is clipped during recording. Ta.

This invention was made in view of the problems of the conventional devices as described above, and provides a magnetic recording device that can reduce the impedance of a transformer without producing a parasitic diode even if a switch is built into a monolithic IC. The purpose is to

[Means for solving problems]

The magnetic recording device according to the present invention is provided with a bias source having a positive voltage as a means for reducing the impedance of the transformer, and is connected to the end of the transformer via a switch.

(Function) In this invention, the other end of the transformer is connected to a low impedance and positive bias source via a switch, so that even if the switch is turned on and both ends of the transformer are short-circuited, the switch remains positive. Since the switch is biased, the generation of parasitic diodes is avoided and the switch is
It can be formed within C.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a magnetic recording device according to an embodiment of the present invention,
In the figure, the same reference numerals as in FIG. 4 indicate the same parts. 1
Reference numeral 6 denotes a low impedance and positive bias source inserted between the switches 1 and 2 and the ground, and in this embodiment, it is formed in a monolithic IC together with the switch 12. For example, as shown in FIG. Diode 16a
and a resistor 16b, or as shown in FIG. 3, transistors 16c, 16d, diode 16e,
A power supply circuit consisting of resistors 16g and 16h can be used.

Next, the effects will be explained.

In this embodiment, by connecting the other end of the switch 12 to a bias source 16 with sufficiently low AC impedance, the left end of the capacitor C2 is charged and becomes equal to the bias voltage when the switch 12 is on, and when the switch 12 is off, A signal is superimposed around the bias while maintaining that potential.

That is, since the terminal 2 is always at a positive potential, the parasitic diode between the collector substrates does not work, and a normal waveform is obtained.

〔Effect of the invention〕

As described above, according to the magnetic recording device according to the present invention, the generation of parasitic diodes can be completely avoided in the switch for reducing crosstalk between heads of a multi-head, and this means can be realized on a monolithic IC. There is an effect that can be done.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing a magnetic recording device according to an embodiment of the present invention, FIG. 1(a) is a circuit configuration diagram thereof, and FIG. 1(b)
, (C) is a diagram showing the waveforms of each part. Figures 2 and 3 are diagrams showing configuration examples of the bias source in Figure 1;
The figure shows a conventional circuit, Figure 5 shows the configuration of the switch in Figure 4, and Figure 6 shows the circuit in Figure 4 as a monolithic IC.
FIG. 6(a) is the circuit diagram, FIG. 6(b) is the waveform diagram of each part, and FIG. 6(C
1 is a sectional view showing the configuration of the switch. In the figure, 10 is a recording amplifier, 11 is a switch, and 12
1 is a switch, CI and Cz are capacitors, 13 is a current limiting resistor, 14 is a rotary transformer, 15 is a head, 16 is a bias source, 20 is a drum, and 21 is a magnetic tape.

Claims (2)

[Claims] (1) In a helical-scan magnetic recording device that has multiple magnetic heads that can simultaneously run on a tape, each secondary side is connected to a corresponding magnetic head, and one end of the primary side is grounded AC or DC. a plurality of recording signal applying means connected to the other end of the primary side of the plurality of transformers and applying a recording signal voltage at a timing corresponding to each head; A plurality of switches, one end of which is connected to the other end of the primary side through a capacitor, are open when the head is recording and conductive when the head is not recording, and a low impedance bias source is connected between the other end of the switch and ground. A magnetic recording device, characterized in that the switch is formed within a monolithic IC. (2) The magnetic recording device according to claim 1, wherein the transistor is an NPN transistor, and the bias source is a positive bias source formed within the monolithic IC.