JPS60247861A - Cassette tape recorder for data - Google Patents

Abstract

PURPOSE:To improve the waveform reproducibility of a signal recorded on a tape for data and to improve the reliability of the tape as a tape cassette for data, by providing a phase shifting circuit in a reproducing system. CONSTITUTION:Signals on a tape having the phase characteristic shown by the curve (a) by dubbing are converted into voltage in the form which is advanced in phase by 90 deg. by the differential characteristic of a reproducing head 11. The signals amplified by a preamplifier 12 thereafter are flattened in frequency characteristic by a reproducing equivalent circuit 13 and become to have the phase shown by the curve (b). The signals are phase-shifted to have the characteristic shown by the curve (c) by the next phase shifting circuit 14 with no change in amplitude. Therefore, signals returned to the phase of almost flat original waveform as shown by the curve (d) are inputted in a power amplifier 15 and outputted from the amplifier 15 after amplification. Moreover, since the phase shifting quantity can be set smaller in the case of an undubbed tape, a phase shifting characteristic as shown by the curve (e) can be used by means of a phase shifting quantity changing switch 16 so as to bring the phase closer to that of the original waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data cassette tape recorder used as an auxiliary storage device for a personal computer.

Conventional configuration and its problems In recent years, cassette tape recorders have become popular as inexpensive auxiliary storage devices for personal computers.
On the other hand, as the standardization of programming languages progresses, the number of commercially available tape cassette software is rapidly increasing. For this reason,
Data cassette tape recorders are now required to be fully compatible with commercially available soft tapes.

A conventional data cassette tape recorder will be described below with reference to the drawings. FIG. 1 shows a circuit of a conventional data cassette tape recorder. In FIG. 1, 1 is a reproduction head, 2 is a preamplifier, and 3 is a reproduction equivalent circuit, which is used to make the frequency characteristics of the reproduction signal peaceful. 4 is a power amplifier.

In the data cassette tape recorder configured as described above, first, the magnetic pattern on the tape taken out by the playback head 1 is amplified by the preamplifier 2, and then the frequency characteristics are flattened by the playback equivalent circuit 3. was made,
The signal is further amplified by the power amplifier 4 and output. However, in the above configuration, the phase of the signal advanced by 90 degrees due to the differential characteristics of the reproducing head 1 is not completely restored by the reproducing equivalent circuit 3. In other words, in the case of a normal tape, the low frequency time constant is 3180μ East and the high frequency time constant is 120μ East, so the amount of phase shift is φ = ta in the case of playback equivalent circuit 3.
n” (XC1/R2)-tan~1(xC1/<
a 1 +R2) ), and the original waveform cannot be completely reproduced. Its characteristics are shown in curve a of FIG. If this is the case, it will not have a big effect on data demodulation, but if this is recorded on a commercially available soft tape and reproduced, the above phase shift amount will be doubled, and the curve in Figure 2 will be the same. As a result, the reliability of data demodulation deteriorates.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a data cursor tape that can obtain high reliability even in data demodulation of commercially available soft tapes by re-correcting the distorted phase characteristics through reproduction and restoration and bringing it closer to the original waveform. The purpose is to provide a recorder.

Structure of the Invention In order to achieve this object, the data cassette tape recorder of the present invention is provided with a phase shift circuit for re-correcting the phase characteristics in the reproducing amplifier system, so that the reproducing equivalent including the reproducing device can be improved. It is characterized by a structure that corrects the lack of phase shift in the circuit and extracts a signal close to the original waveform.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the 1g plane. FIG. 3 shows a circuit of a data cassette tape recorder according to an embodiment of the present invention. In FIG. 3, 11 is a reproducing head, 12 is a preamplifier, and 13 is a reproducing head.
14 is a variable phase shift circuit, and 15 is a power amplifier.

In the data cassette tape recorder configured as described above, first, the signal of the tape which has been reproduced and has a phase characteristic as shown by the curve d in FIG.
Due to the differential characteristics of , it is converted into a voltage with a phase advance of 90 degrees. The signal amplified by the preamplifier 612 is then flattened in frequency characteristics by the reproduction equivalent circuit 13,
The phase has characteristics like the curve in FIG. This signal is phase-shifted in the next phase shift circuit 14 with a characteristic as shown by curve C in FIG. 2 without any change in amplitude. Therefore, the power amplifier 15
As shown by curve d in FIG. 2, a signal whose phase has been returned to the original waveform which is almost flat is inputted to the input circuit 2, and is amplified and outputted.

In addition, in the case of a tape that has not been reproduced, since the amount of phase shift may be small, the variable phase shift switch 16 can be used to obtain a phase shift characteristic as shown by curve e in FIG. 2, thereby making it possible to approximate the phase of the original waveform.

As described above, according to this embodiment, by providing the variable phase shift circuit 14 in the regenerative amplifier system, the phase can be adjusted to match the phase of the original waveform, not only on a tape that has been recorded only once, but also on a copied soft tape. It is possible to return to an approximate state.

In the above embodiments, the phase shift circuit 14 is of a variable type, but the phase shift circuits 14 and 14 may be fixed near the middle of both characteristics. Although the phase shift amount variable switch 16 has two stages, it goes without saying that the number of stages may be increased or a variable resistor may be used instead.

To explain the phase shift circuit 14 in more detail, R3,
R4 is the bias resistance of transistor Q1, R51R6
is the load resistance and has a similar value.

C2 and C4 are DC blocking capacitors, and the resistor RR determines the phase shift frequency together with the capacitor C3. In this phase shift circuit 14, when a voltage υ is applied to the base of the transistor Q1, a voltage υ appears at the emitter and a voltage 1υ appears at the collector, and the resistor R7°R and capacitor C3 have a voltage t an ' with respect to this voltage. (1/ωC2(
R7+Ra) Current i flows in the direction that advances by l.

υ(R7+R8) and -υ(R
7 + R8) occurs, and voltage drops of υC3 and -υC3 occur in the direction 90 degrees behind this undercurrent, capacitor C3 is the load for υ, and resistor R is for -〇.
7, R8 acts as a load, so the voltage at the output point is −υ(
R7+R8) and υC3, the amplitude is independent of frequency, and 2 tan ” (ωc3(R
7+Ft8)) It is possible to obtain a voltage whose phase is delayed.

Effects of the Invention As described above, the data cassette tape recorder of the present invention improves the waveform reproducibility of the signal recorded on the data tape by providing a phase shift circuit in the playback system. This has the advantage that reliability as a cassette can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional data cassette tape recorder, FIG. 2 is a phase characteristic diagram, and FIG. 3 is a block diagram showing an embodiment of a data cassette tape recorder according to the present invention. 11... Reproduction head, 12-... Preamplifier,
13...Reproduction equivalent circuit, 14...Variable phase shift circuit, 15. Luca amplifier. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3

Claims (1)

[Claims] A data cassette tape recorder characterized in that a regenerative amplifier system is equipped with a phase shift circuit for phase correction.