JP3021612B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing head, a reproducing circuit, and a switching circuit for a recording circuit used in a magnetic recording / reproducing apparatus.

2. Description of the Related Art As a magnetic recording / reproducing apparatus for digital signals, for example, R
Devices such as a rotary head type called a DAT system or a fixed head type digital audio tape recorder called an S-DAT system, a rotary head type digital VTR, and a rotary head type digital data streamer have been developed.

Hereinafter, the conventional R-DAT described above with reference to the drawings.
An example of a recording / reproducing switching circuit of a digital audio tape recorder based on the system will be described.

FIG. 3 shows a cylinder section and a recording / reproducing section of a digital audio tape recorder based on the R-DAT system.

In FIG. 3, a cylinder section is constituted by the heads 1 and 2 and a rotary transformer. Transistors Q1, Q2 and resistors R1, R2
This constitutes a second switching element for recording and reproduction. The transistors Q3 and Q4 and the resistors R3 and R4 constitute a first switching element for recording and reproduction.

A regenerative amplifier is constituted by the amplifiers 1 and 2. The recording amplifier is constituted by the amplifiers 3 and 4. As the recording signal 1, a recording signal corresponding to the time during which the head 1 is in contact with the magnetic tape during recording is supplied from a signal processing circuit. As the recording signal 2, a recording signal corresponding to the time during which the head 2 is in contact with the magnetic tape during recording is supplied from a signal processing circuit. Recording / playback switching signal 1
Is supplied from the signal processing circuit at a high level during recording. The recording / playback switching signal 2 is low when recording.
Is supplied from the signal processing circuit.

The operation of the recording / reproducing switching circuit of the digital audio tape recorder based on the R-DAT system configured as described above will be described below.

At the time of recording operation, the recording / reproduction switching signal 1 is high at the time of recording and turns on the transistors Q1 and Q2 via the resistors R1 and R2 to ground one end of the rotary transformer. Also, a recording / playback switching signal 2
Is low at the time of recording, the transistors Q3, Q4 through the resistors R3, R4
And turn off one end of the rotary transformer from the ground. Therefore, the recording signal 1 is the amplifier 3 and the recording signal 2 is the amplifier 4
, And are amplified by the rotary transformer and recorded by the head 1 and the head 2, respectively.

At the time of the reproducing operation, while the head 1 or the head 2 is in contact with the magnetic tape, it is electromagnetically exchanged corresponding to each head and becomes a reproduced signal. The reproduced signal is reproduced by the amplifier 1 or 2 of the reproducing amplifier via the rotary transformer.

The recording / playback switching signal 1 is low at the time of playback, and the resistors R1 and R2
To turn off the transistors Q1 and Q2 to release one end of the rotary transformer from the ground. The recording / playback switching signal 2 is
At the time of reproduction, the transistors Q3 and Q4 are turned on via the resistors R3 and R4 and one end of the rotary transformer is grounded. Therefore, the reproduced signal becomes a reproduced signal amplified by the amplifiers 1 and 2, and is reproduced as an audio signal by the signal processing circuit of the next stage.

However, in the above-described configuration, the recording current of the head is determined by the driving capability (power supply voltage) of the recording amplifier. In order to reduce the size and portability of the digital audio tape recorder, a low voltage is required. Therefore, a recording amplifier that can be driven by the above is required.

Further, in the specification using a plurality of heads, the number of wirings between the cylinder portion and the recording / reproducing circuit increases, the circuit becomes complicated, and the price increases.

When a switching operation is performed by flowing a recording current through a transistor, the operating impedance of the transistor changes due to a change in the current, and waveform distortion of the recording current occurs. Further, when the input of the reproducing amplifier is directly connected to the output of the recording amplifier, a current flows through the reproducing amplifier during recording, resulting in waveform distortion of the recording current and destruction of elements at the input stage of the reproducing amplifier.

At the time of reproduction, the reproduction frequency characteristics deteriorate due to the output capacity of the recording amplifier, and the reproduction S / N deteriorates due to current noise due to leakage current flowing into the output of the recording amplifier.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a switching circuit for a reproducing circuit and a recording circuit of a magnetic recording / reproducing apparatus that realizes a high-performance reproducing amplifier with a low-voltage recording circuit connection and a small waveform distortion. Aim.

Means for Solving the Problems In order to solve the above-mentioned problems, the means of the present invention provides wiring of a plurality of heads and a recording / reproducing circuit, using one terminal of each of the plurality of heads as a common wiring, and connecting each other terminal to each other. Signals are transmitted by independent wiring. On the common wiring side, the recording amplifier and the first switching element are connected, and during reproduction, the first switching element is connected to the ground. On the other hand, the plurality of independent wirings are connected to the bases of the plurality of reproduction amplification transistors and the plurality of second switching elements corresponding to the wirings,
At the time of recording by the second switching element, a plurality of recording amplifiers are connected to recording amplifiers of opposite phases corresponding to the wirings. The emitters of the plurality of reproduction amplification transistors are connected to a third switching element as a common wiring, and are connected to the ground at the time of reproduction by the third switching element. Recording and reproduction are performed by switching the switching elements in the above configuration.

Also, at the time of recording, a direct current flows through the switching element connected between the independent wiring and the recording amplifier having the opposite phase.
A bias resistor is connected to each recording amplifier.

The above-mentioned means at the time of recording is changed from one independent wiring connected by switching a plurality of second switching elements connected to each other by replacing a plurality of recording amplifiers having opposite phases with one recording amplifier having opposite phases. Is selected and recorded.

According to the present invention, the recording current can be improved by the recording amplifiers of the positive and negative phases during recording, the number of wirings can be reduced by the wiring method between the head and the amplifier, and the waveform distortion at the time of recording can be improved by adding a bias resistor. With the switching element, it is possible to improve the S / N deterioration of the reproduction amplifier and realize the switching operation of recording and reproduction under appropriate conditions.

Embodiment A recording / playback switching circuit of a digital audio tape recorder based on the R-DAT system according to an embodiment of the present invention will be described below.

FIG. 1 shows a configuration of a recording / playback switching circuit of a digital audio tape recorder based on the R-DAT system in the first embodiment.

In FIG. 1, a head 1 and a head 2 and a rotary transformer constitute a cylinder unit, and transistors Q1 and Q2 and resistors R1 and R2 constitute a second switching element for recording and reproduction. The transistor Q3 and the resistor R3 constitute a first switching element for recording and reproduction, and the transistor Q4 and the resistor R4 constitute a third switching element for recording and reproduction. The transistors Q5 and Q6 and the resistors R5 and R6 form the first stage of the reproducing amplifier. The amplifiers 1 and 2 are inverting amplifiers of the recording signal. The amplifiers 1 and 2 and the amplifier 3 constitute a recording amplifier. The resistors R7, R8, and R9 form a bias circuit. The recording signal 1 supplies a recording signal corresponding to the time during which the head 1 is in contact with the magnetic tape during recording from the signal processing circuit, and the recording signal 2 corresponds to the time during which the head 2 is in contact with the magnetic tape during recording. A recording signal is supplied from a signal processing circuit. The recording signal 1-2 is a composition of the recording signal 1 and the recording signal 2, and the recording signal is supplied from the signal processing circuit. The recording / reproduction switching signal 1 is supplied from the signal processing circuit when recording is high. Recording / playback switching signal 2
Is supplied from the signal processing circuit at a low level during recording.

The operation of the recording / playback switching circuit of the digital audio tape recorder based on the R-DAT system configured as described above will be described below.

The switching operation to recording is performed by a recording / reproducing switching signal 1 and a recording / reproducing switching signal 2. The recording / reproducing switching signal 1 is high at the time of recording and is connected to the transistors Q1 and R2 via the resistors R1 and R2.
Turn on Q2 and turn on one end of the rotary transformer and amplifiers 1 and 2 of the recording amplifier.
Connect. On the other hand, the recording / reproduction switching signal 2 turns off the transistors Q3 and Q4 via the resistors R3 and R4 when recording is low.
The transistor Q3 releases the other end of the rotary transformer from the ground. Transistor Q4 releases the common emitter of transistors Q5 and Q6 from ground.

The bias circuit flows from the power supply to the ground through the rotating transformer, the transistors Q1, Q2 and the resistors R7, R8 from the resistor R9. Therefore, the recording signal 1-2 is amplified by the amplifier 3 of the recording amplifier, and the recording signal 1 is amplified by the amplifier 1 of the recording amplifier having the opposite phase, drives the rotary transformer, causes a current to flow through the head 1, and contacts the magnetic tape. Record only the time you have. The recording signal 2 is amplified by the amplifier 2 of the recording amplifier having the opposite phase, and the rotary transformer is driven by the output of the amplifier 3 to supply current to the head 2 and record only during the time when the head is in contact with the magnetic tape.

In the reproducing operation, the time when the head 1 or the head 2 is in contact with the magnetic tape is electromagnetically converted corresponding to the respective heads to become a reproduced signal.

The switching operation to the reproduction is performed by the recording / reproduction switching signal 1 and the recording / reproduction switching signal 2. The recording / reproduction switching signal 1 is low at the time of the reproduction and is connected to the transistors Q1 and R2 via the resistors R1 and R2.
Turn off Q2 and release the other end of the rotary transformer from the ground.
The recording / playback switching signal 2 is high at the time of playback and the resistors R3, R
The transistors Q3 and Q4 are turned on via 4. Transistor Q3
Ground one end of the rotary transformer. Transistor Q4
Grounds the common emitter of transistors Q5 and Q6.

Therefore, the reproduction signal reproduced from the head is amplified by the transistors Q5 and Q6 of the reproduction amplifier via the rotary transformer, the reproduction signal of the head 1 becomes the reproduction output 1 and the reproduction signal of the head 2 becomes the reproduction output 2, and The audio signal is reproduced by the signal processing circuit.

As described above, according to the present embodiment, the number of wirings can be reduced by using one of the rotary transformers as a common wiring and the other as an independent wiring for the wiring of the cylinder unit and the recording and reproducing circuit.

Further, at the time of recording, a driving current can be supplied with a half power supply voltage by driving the rotary transformer with a recording amplifier having a normal phase and a reverse phase.

In addition, by applying a DC current to the transistors Q1 and Q2 of the switching element by the bias circuit, the O
At N, the impedance can be reduced and the waveform distortion of the recording current can be improved. Also, transistors Q5 and Q of the regenerative amplifier
6 common emitters as switching element transistor Q4
, It is possible to prevent a current from flowing from the base to the emitter of the transistors Q5 and Q6 of the reproducing amplifier by the driving voltage of the recording amplifier having the opposite phase. At the time of reproduction, by turning off the transistors Q1 and Q2 of the switching element, unnecessary loads are not connected to the rotating transformer and the transistors Q5 and Q6 of the reproduction amplifier, so that the S / N and the frequency characteristics can be improved.

FIG. 2 shows a configuration of a circuit for switching recording / reproduction of a digital audio tape recorder based on the R-DAT method in the second embodiment.

In FIG. 2, heads 1 and 2 have the same configuration as FIG.
2 and a rotary transformer constitute a cylinder unit, and transistors Q1, Q2 and resistors R1, R2 constitute a second switching element for recording and reproduction. The transistor Q3 and the resistor R3 constitute a first switching element for recording and reproduction, and the transistor Q4 and the resistor R4 constitute a third switching element for recording and reproduction. Transistors Q5, Q6 and resistors R5, R6
Constitutes the first stage of the regenerative amplifier. The recording signal 1-2 is a composite of the recording signal 1 and the recording signal 2, and the recording signal is supplied from the signal processing circuit. The recording / reproduction switching signal 2 is supplied from the signal processing circuit at a low level during recording. The above is the first
This is similar to the configuration shown in the figure.

The difference from the configuration shown in FIG. 1 is that the amplifier 1 is an inverting amplifier of the recording signal, and that the amplifier of the amplifier 2 constitutes a recording amplifier and that the resistors R8 and R9 constitute a bias circuit. The recording / reproducing switching signal 1-1 is a signal that is high only during a period in which the head 1 performs recording on the magnetic tape during recording and is supplied from the signal processing circuit. 1 in that it is supplied from the signal processing circuit with a signal that goes high only during a period in which the head 2 performs recording on the magnetic tape.

The operation of the recording / playback switching circuit of the digital audio tape recorder based on the R-DAT system configured as described above will be described below with reference to the operation of the second embodiment.

The switching operation to recording is performed by a recording / playback switching signal 1-.
Perform steps 1, 1-2 and 2.

The recording / reproduction switching signal 1-1 is synchronized with the recording signal corresponding to the head 1 of the recording signal 1-2, and turns on the transistor Q1 via the resistor R1 at a high level to connect one end of the rotary transformer to the amplifier 1 of the recording amplifier. I do. Recording / playback switching signal 1-
Reference numeral 2 denotes a section where the head 2 is in contact with the magnetic tape during recording, and in synchronization with the recording signal corresponding to the head 2 of the recording signal 1-2, the transistor Q2 is turned on via the resistor R2 at a high level to connect with one end of the rotary transformer. The amplifier 2 of the recording amplifier is connected.

On the other hand, the recording / reproducing switching signal 2 turns off the transistors Q3 and Q4 via the resistors R3 and R4 at the time of recording low similarly to FIG. The transistor Q3 releases one end of the rotary transformer from the ground. Transistor Q4 releases the common emitter of transistors Q5 and Q6 from ground.

The bias circuit consists of a rotating transformer from the power supply, a resistor R9, a transistor with transistors Q1 and Q2 turned on, and a resistor R8.
Through to earth.

Therefore, the recording signal 1-2 is amplified by the amplifier 1 of the recording amplifier and the amplifier 2 of the recording amplifier having the opposite phases, and the transistors Q1 and Q2 select the heads 1 and 2 and flow the current to the head via the rotary transformer, thereby causing the head 1 Alternatively, recording is performed only during the time when 2 is in contact with the magnetic tape.

Therefore, the reproduction signal reproduced from the head is amplified by the transistors Q5 and Q6 of the reproduction amplifier via the rotary transformer, the reproduction signal of the head 1 becomes the reproduction output 1 and the reproduction signal of the head 2 becomes the reproduction output 2, and The signal is reproduced as an audio signal by the signal processing circuit.

As described above, according to this embodiment, at the time of recording, a signal obtained by adding the head to the recording / reproduction switching signal and the rotary transformer is driven by the recording amplifiers having the normal phase and the opposite phase, so that one phase is reversed. Can be driven by the recording amplifier.

As described above, according to the present invention, the signal transmission path of the cylinder unit and the recording / reproducing circuit is configured such that one side of the head is provided with a common wiring and the other is provided with an independent wiring. By providing a configuration that switches the amplifier and applies a DC bias to the switching element with a bias circuit at the time of recording, the recording current is improved by the recording amplifier of the normal phase and the opposite phase at the time of recording, and the number is reduced by the wiring method between the head and the amplifier. In addition, it is possible to improve the waveform distortion at the time of recording by adding a bias resistor, and to improve the S / N deterioration of the reproducing amplifier by using the switching element, thereby realizing the switching operation of recording and reproducing under suitable conditions.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration for switching between recording and reproduction in the magnetic recording and reproducing apparatus according to the first embodiment of the present invention, and FIG. 2 is a diagram illustrating switching between recording and reproducing in the magnetic recording and reproducing apparatus according to the second embodiment of the present invention. FIG. 3 is a circuit diagram showing a configuration, and FIG. 3 is a circuit diagram showing a configuration for switching between recording and reproduction in a conventional magnetic recording and reproducing apparatus. C1, C2 …… DC cut capacitors, R1, R2, R3, R4, R5, R
6, R7, R8, R9 ... bias resistors, Q1, Q2, Q3, Q4 ... switching transistors, Q5, Q6 ... reproduction signal amplification transistors.

Claims (3)

(57) [Claims] 1. A means for transmitting a signal between a plurality of heads and a recording / reproducing circuit, using one terminal of each of the plurality of heads as a common wiring and transmitting the other terminal as an independent wiring, and a recording amplifier and a recording amplifier on the common wiring. Means for connecting a first switching element, grounding the common wiring at the time of reproduction with the first switching element, and connecting a plurality of second switching elements corresponding to the independent wiring, the second switching element Means for connecting each independent wiring to a plurality of write amplifiers having the opposite phases of the write amplifier at the time of recording, and connecting the bases of a plurality of read / amplify transistors to the independent wires and using a common emitter for the read / amplify transistors, And a means for grounding a common emitter at the time of reproduction by the third switching element. Recording and reproducing apparatus. 2. The magnetic recording / reproducing apparatus according to claim 1, further comprising a bias circuit for supplying a direct current to a second switching element connected between the independent wiring and the recording amplifier having the opposite phase during recording. 3. A means for transmitting a signal between a plurality of heads and a recording / reproducing circuit, using one terminal of each of the plurality of heads as a common wiring and transmitting the other terminal as an independent wiring, and a recording amplifier and Means for connecting a first switching element, grounding the common wiring at the time of reproduction with the first switching element, and connecting a plurality of second switching elements corresponding to the independent wiring, the second switching element Means for selecting one of the independent wirings at the time of recording and connecting to the recording amplifier having the opposite phase of the recording amplifier during recording, and connecting the bases of a plurality of reproduction amplification transistors to the independent wiring and setting the emitter of the reproduction amplification transistor Means for connecting a common switching element and grounding the common emitter during reproduction with the switching element. Magnetic recording and reproducing apparatus according to symptoms.