JPS5898810A - Sound recording circuit for multichannel tape recorder - Google Patents

Abstract

PURPOSE:To eliminate the crosstalk between channels, by making the secondary impedance of a multichannel secondary coil, which is wound around the core of an oscillation coil, lower than the resultant impedance of a sound recording head and a sound recording current equalizer. CONSTITUTION:A frequency for sound recording bias is oscillated by one oscillating circuit consisting of a transistor TR16, a resistance 15, and a primary coil 10a of a transformer 10, and recording current bias currents induced in secondary coils 10b and 7b wound around the same core are supplied to magnetic heads 6a and 6b of two channels. If the secondary impedance of the transformer 10 in the frequency band of a sound recording signal is made lower sufficiently than the resultant impedance of magnetic heads 6a and 6b and sound recording current equalizers 9a and 9b, the crosstalk of the sound recording current between channels is ignored even if multichannel secondary coils are wound around the same core.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording circuit for a multichannel tape recorder.

FIG. 1 shows an example of a recording circuit of a conventional multi-channel tape recorder. When recording, press the recording/playback switch 81-S.
7 are in contact with the contact point R, respectively, as indicated by the center line in the figure. Recording input is input from the left-opening microphone 1α and the right-side microphone α phon 1b, and is passed through the selector switches S, , S, and J expanders 2α, 26, respectively.
His mouth widens. Amplified #l! The sound signals pass through changeover switches S3 and S, respectively, and enter recording equalizers 9a and 91r consisting of parallel circuits of resistors and capacitors. I traced the record #Tunryu Ikoshiiza 9α, 91) and thought about it,
The circuit consisting of the secondary coil 10b of the transformer 10 and the capacitor 12 (Z), the circuit consisting of the secondary coil 76 and the capacitor 125 of the transformer 7, and the respective magnetic Head 6a.

Recorded on tape with 6z.

Also, a transistor 16, a resistor 15 and a transformer 10
primary coil 10α, transistor 8, resistor 1
1 and the primary coil 7α of the transformer 7 each constitute an oscillator. Recording bias currents induced in the secondary sides of transformers 1o and 7 by these oscillator outputs are supplied to heads 6α and 66 from coils 105.7A on the front secondary side, respectively. Further, the output of the oscillator is applied to a degaussing head 14, and the 4JR tape is erased by this head 14.

During playback, the recording/playback selector switches S1 to S are connected to contact p.
Switched to H10. Therefore, the magnetic head 6α
, 66 reproduces signal 1g to amplifier 2α.

26, and passes through resistors 3a and 54 and output amplifiers 4a and 4b, and the left reproduction signal is output to the speaker 5.
The reproduced signal from the right 11fO is converted into audio by the speaker 56.

In addition, in the circuit of FIG. 1, 13 is a turtle W switch, 1
7 is 4 ken.

However, from point 7, in the conventional recording circuit described above,
The magnetic head 6 for recording and playback (1.6bK recording bias DC?!A oscillator for providing the same number of channels as the number of channels is required, which has the drawback of requiring a large number of parts and increasing manufacturing costs.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide a recording circuit for a multi-channel tape recorder capable of producing moving images with a small number of parts.

The present invention provides a multichannel tape recorder in which at least one excavation circuit for supplying recording bias current to at least two or more recording heads is wound around the core of an oscillation coil of the one oscillation circuit. Secondary coils for at least 2+m channels and capacitors connected in parallel with each secondary coil? The main feature of the Knee-X is that the secondary impedance of the oscillating coil is selected to be sufficiently smaller than the combined impedance of the recording head and recording current equalizer in the recording signal frequency band.

The present invention will be explained in detail below. Figure 2 shows an example of the present invention. The secondary coil of the transformer connected to each magnetic head is wound around the same core.In other words, transistor 1
6. Resistor 15 and primary coil 10α of transformer 10
The recording bias frequency is oscillated by one oscillation circuit consisting of a 71mm secondary coil wound around the same core.
The high bias id flow induced by iy and yb was supplied to the two-channel a air heads t5a and 6iS. It is a book. In addition, Fig. 2 1c 16, 1st
The same reference numerals as in the figure indicate the same parts as in Fig. 41. In addition, the circuit operations for recording and playback are the same as those of the VT/US subcircuit, so a description thereof will be omitted.

Generally, the signal oscillated by the oscillator 12 needs to be higher than the highest recording frequency.

This implementation U is designed to obtain an oscillation frequency of 30 to 100 K11z, and the secondary impedance of the transformer 10 is high near this oscillation frequency, as shown by the curve α in Figure 3, and the oscillation frequency It gets smaller as you move away from it. On the other hand, the magnetic head 6α.

The impedance for the frequency of 6 is the straight line 6 in Figure 3.
The frequency increases linearly from around 7 to 80 QHz. In addition, the recording power source Ikoshiiza 9α.

The impedance for the frequency 9b decreases almost linearly beyond IK11z, as in song M'. The combined impedance of the magnetic head and the recording spiral equalizer is as shown by the curve d indicated by the dotted line.

Here, if the secondary impedance of the transformer 10 in the recording signal frequency band is selected to be sufficiently small compared to the combined impedance d of the magnetic head and the Kama-on-ra flow equalizer, as shown by the curve α in FIG. Even if the secondary coil of the channel is wound, the record of -10,000 channels is tt'IK.
This makes it possible to ignore stratification effects induced in the secondary coils of other channels. For this reason, the crosstalk that occurs when multiple channels of secondary coils are wound around the same core is extremely small, making it practical for recording to flow to the recording heads 6α and 6b of each channel. There is no deterioration of No. 1.

As described above, according to the present invention, multiple channels of secondary coils are wound around the core of the same oscillation coil, and the secondary impedance of the secondary coil is adjusted between the recording head and the recording magnetic current equalizer in the signal frequency band. Since it is chosen to be sufficiently small compared to the composite impedance, there is almost no crosstalk in the recording current between channels, and it has the effect of being able to be used in inexpensive multi-channel tape recorders with a small number of parts. .

[Brief explanation of drawings]

FIG. 41 is a circuit diagram showing an example of a recording circuit of a conventional multi-channel tape recorder, and FIG. 2 is a circuit diagram showing an example of a recording circuit of a multi-channel tape recorder according to the present invention.
FIG. 3 is a characteristic diagram showing the characteristics of the oscillation coil secondary impedance, magnetic head impedance, and recording 4A equalizer impedance. 10...Transformer 1oα...-Next coil 7
A, 10A...Secondary carp/l/ 12a, 12A...
・Capacitor 15...Resistor 16...Transistor Fig. 1-a Fig. 2

Claims (1)

[Claims] (1) In a multichannel tape recorder in which each channel of two or more channels has its own recording input, amplifier, recording current equalizer, and recording head, a recording bias current is supplied to at least two or more recording heads. At least 11 oscillations I! 121 path, comprising secondary coils for at least two channels wound around the core of the oscillation coil of the one oscillation circuit, and a capacitor connected in parallel with each secondary coil, and The next coil and the oscillator capacitor are connected in series between the output of the amplifier of each channel and each recording head, and the oscillation coil 2 A recording circuit for a multi-channel tape recorder characterized in that the next impedance is selected to be sufficiently smaller than the impedance of the recording head and the equalizer.