JPS6355706A - Diagnosis circuit for magnetic tape device - Google Patents

Abstract

PURPOSE:To improve quality recorded on a magnetic tape by inserting a diode into a signal line between plural magnetic heads and plural drive circuits and connecting them so that any channels bias them in the normal direction. CONSTITUTION:If, with a drive signal given to the input terminal 1a of the channel 1, a transistor Q15 in the drive circuit cannot operate normally, the level of an output terminal 1c becomes a high level, and the diode D1c is reversely biased. Then the input terminal (e) of a level detector 3 comes to a level higher than that of a threshold voltage VT. Accordingly, since the output terminal (g) detects a high level, the faults and deteriorations of the drive circuits 12-n2 and the magnetic heads 11-n1 can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diagnostic circuit for a magnetic tape device, and more particularly to a diagnostic circuit for a pulse magnetic recording type magnetic tape device having a multi-track head.

[Conventional technology]

Conventionally, this type of magnetic tape device has not been equipped with a diagnostic circuit.

[Problem that the invention seeks to solve]

The above-described conventional magnetic tape device has the disadvantage that even if one of the multi-track heads is damaged, it cannot be detected because error correction operates. Furthermore, if the magnetic head or drive circuit deteriorates and an appropriate recording current cannot be applied to the magnetic tape, a magnetic tape with poor recording quality may be produced. If such magnetic tapes are stored for many years, reading errors will occur when they are played back.

[Means for solving problems]

A diagnostic circuit for a magnetic tape device according to the present invention is used in a magnetic tape device that performs pulsed magnetic recording of a multi-track head.
A level detector is provided which is connected to one pole of a diode provided at the output of each drive circuit to apply an appropriate pulse current to each magnetic head of the multi-track head, and detects an appropriate current flowing through each magnetic head. It is composed of

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.
・Channel 1, channel 2, etc., which constitute one track. ~Respective magnetic heads 11, 21 . . . of channel N.
Diodes Dlc and Dld whose cathodes are connected to the signal lines between ~n1 and the drive circuit 12゜22 and ~n2, respectively.
, D2c, D2d to Dne and DIld, a resistor R8 that connects all of the anode sides of these diodes and allows current to flow therethrough, and a level detector 3. Further, in each drive circuit, for example, the drive circuit 12, an input terminal l
a, base of transistor Q15 via lb, Q16
A signal for driving the magnetic head 11 is applied to the base of each of the magnetic heads. The emitters of transistors Q15 and Q16 are grounded, and the collector of transistor Q15 is connected to the output terminal IC.
is connected to one end of the resistor R,13, and the transistor Q16
The collector of is connected to the output terminal 1d and one end of the resistor R14. The other ends of resistors R13, R, and 14 are power supply ■. Connected to 0. Note that the drive circuit 22. ~n2 also have the same configuration as the drive circuit 12, respectively.

Next, the operation of the present invention will be explained with reference to FIG. 2 which shows the level waveforms of each part shown in FIG. 1.

When a signal for driving the magnetic head 11 of channel 1 is applied to the input terminal 1a of the drive circuit 12, the transistor Q1
5 is turned on, and the output terminal IC becomes low level. Therefore, the current shown by the arrow i flows through the magnetic head 11.

Next, when a signal for driving the magnetic head 21 of channel 2 is applied to the input terminal 2a of the drive circuit 22, a current flows in the magnetic head 21 in the direction of arrow 12, similar to the operation shown in channel 1. In this way, drive current is applied up to channel N. Subsequently, when a drive signal is applied to the input terminal 1b of the drive circuit 12 of channel 1, the transistor Q
16 turns on and makes the output terminal 1d a low level. Therefore, a current flows in the magnetic t\rad 1 in the direction opposite to the arrow j1 6Similarly, the channel 2. A drive signal is applied to input terminals 2b and -nb of ~channel N.

When the drive signals are sequentially applied in this manner, the output terminals IC, 2C to nc and ld of each channel.

In the signals 2d to nd, some channel is always at a low level. Therefore, the magnetic head 11 +' of each channel
Diode D connected to the signal line 21, ~n1
IC and Dl, 1. D2e and D24. ~D nc and Dad
is always forward biased somewhere and vice versa. Therefore, each magnetic head 11, 21 .
When a normal current is flowing through n1, the level at the input terminal e of the level detector 3 is at a low level. Since the threshold voltage VT is applied to the input terminal f of the level detector 3, its output terminal g becomes a low level.

Here, even though the drive signal is applied to the input terminal 1a of channel 1, the transistor Q15 of the drive circuit 12
cannot operate normally (that is, it does not reach a low level), the level at the output terminal IC becomes high as shown by the dotted line, and the diode D1c becomes reverse biased, causing the voltage at the input terminal e of the level detector 3 to decrease. becomes higher than the threshold voltage VT. Therefore, a high level is detected at the output terminal g. In this way, it is possible to detect that a normal current flows through the magnetic head of each channel.

〔Effect of the invention〕

As explained above, the present invention inserts a diode into the signal line between each magnetic head and the drive circuit of a magnetic tape device that performs multi-track pulsed magnetic recording, so that the diode is always connected in the forward direction in some channel. By connecting it so that it is biased and detecting the signal with a level detector, it is possible to detect failures or deterioration of the drive circuit and magnetic head. This improves the quality recorded on magnetic tape and increases the reliability of magnetic This has the effect of providing a tape device. Furthermore, since the diagnostic circuit is extremely simple, its reliability is also high. FIG. 2 is a time chart diagram showing level waveforms of each part in FIG. 1;

1.2~N, , Channel, 11.21. ~n1-・-
Magnetic head, 12.22. ~n2...drive circuit, 3.
...Level detector, la, lb, 2a, 2b, ~na,
nb, e, f---input terminal, IC, ld, 2c, 2d
, ~nc, nd, g・-・output terminal, D IC+Dl
d, D2c, D2d, ~D nc + D nd...
Diode, Ro, R13, R14...Resistance, Q15
．． Q16-,.

L.Rangista.

Kaya I

Claims (1)

[Claims] In a magnetic tape device that performs pulsed magnetic recording of a multi-track head, each magnetic head is connected to one pole of a diode provided at the output of each drive circuit that provides an appropriate pulse current to each magnetic head of the multi-track head. A diagnostic circuit for a magnetic tape device, comprising a level detector that detects an appropriate current flowing through a head.