JPH0746408B2 - Recording amplifier circuit of magnetic recording and reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / amplifying circuit of a magnetic recording / reproducing apparatus which uses an operational amplifier in a recording circuit and obtains a recording peaking characteristic suitable for various tapes without using a coil. Is.

Configuration of Conventional Example and Its Problems In recent years, the price reduction of audio products has been remarkable, and the number of coils and capacitors used in electronic circuits has become a bottleneck in price reduction.

Hereinafter, a recording amplifier circuit of a conventional magnetic recording / reproducing apparatus for supplying a recording current to the head will be described.

FIG. 1 is a circuit diagram showing a recording amplifier circuit of a conventional magnetic recording / reproducing apparatus. There is a coupling capacitor C ₁ between the input terminal 1 and the + input terminal 4 of the operational amplifier 3, and
A bias resistor R ₁ is connected between the input terminal 4 and ground. From the output terminal 6 of the operational amplifier 3, the coupling capacitor C ₂ , the constant current resistor R _2, and the head 2 are connected between the ground. Between the negative input terminal 5 of the operational amplifier 3 and the ground, there is a resistor R ₂ and a resistor R ₂ when the switch SW ₂ is closed.
₂ to be a parallel resistance R _4, a resistor R ₅ to the resistor R ₂ becomes parallel when the switch SW3 is closed, further resistor R _3, the coil
Series circuit of L ₁ and capacitor C ₃ , and capacitor C ₄ connected in parallel with capacitor C ₃ when switch SW1 is closed.
Are connected. Further, an NF resistor R ₆ is connected between the inverting input terminal 5 and the output terminal 6.

In the recording amplifier circuit configured as described above, the input signal is applied to the input terminal 1 and is applied to the + input terminal 4 of the operational amplifier 3 through the coupling capacitor C ₁ . R ₁ is a bias resistor used to set the output DC voltage of the operational amplifier 3 near the ground potential. The output from the output terminal 6 of the operational amplifier 3 is passed through the coupling capacitor C ₂ .
A recording current is supplied to the head 2 through the constant current resistor R ₂ . However, the recording current characteristic supplied to the head 2 has many loss factors such as gap loss and space gloss at a high frequency, and the recording current has a sharp peaking characteristic as shown in FIG. 4 to compensate for it. Will be required. Therefore, the operational amplifier 3 shown in FIG. 1 has a non-inverting amplifier circuit configuration, and has a resistor R ₃ , a coil L ₁ , a capacitor C ₃ (when the switch SW 1 is closed, which is connected between the − input terminal 5 and the ground. A series resonance circuit determined by the combined capacitance of the capacitors C ₃ and C ₄ ) is used to obtain a recording current having a sharp peaking characteristic as shown in FIG.

The operation of the basic circuit of the conventional example when the switches SW1, SW2 and SW3 are open will be described below. Considering the gain of this non-inverting amplifier circuit, the gain G is Can be expressed as

Generally, R ₃ << R ₂ , R ₂ << R ₆ is set, so in the low frequency range And again It has a sharp peaking characteristic, and the entire recording current characteristic can be obtained as shown in FIG.

However, actually, it is necessary to change the recording current characteristics and the recording current sensitivity depending on the type of various tapes, for example, normal, chrome, and metal tapes, which is shown in FIG.

In order to obtain the characteristics of FIG. 5, the switch SW1, of the circuit diagram of FIG.
SW2 and SW3 are required. A conventional example for obtaining a recording current characteristic according to various tapes will be described below.

First, to obtain the recording current characteristics that match the normal tape, SW1 is closed and SW2 and SW3 are opened. Therefore, the recording peaking frequency is And the gain at low frequencies is Thus, the normal recording current characteristic shown in FIG. 5 is obtained.

Next, in order to obtain the recording current characteristic matched with the chrome tape, the switch SW1 is opened, the switch SW2 is closed, and the switch SW3 is opened. Therefore, the recording peaking frequency is The frequency becomes higher than the recording peaking frequency ₁ in the normal state. Also, the gain at low frequencies is And gain for normal It becomes higher, and the chrome recording current characteristic shown in FIG. 5 is obtained.

Next, to obtain the recording current characteristic matched with the metal tape, the switches SW1 and SW2 are opened and the switch SW3 is closed.
The recording peaking frequency is the same as the peaking frequency during chrome, and the gain at low frequencies is Therefore, by setting the resistance value to R ₄ > R ₅ , it can be set higher than the low frequency gain at the time of chrome, and the recording current characteristic of metal shown in FIG. 5 can be obtained.

As explained above, to obtain a recording current characteristics corresponding to various tape, but is performed switching of the capacitor C _3, C ₄ of the switching resistor R _4, R _5, in fact, the resistance R _4, R _A capacitor or a series circuit of a capacitor and a resistor is often connected in parallel with ₅ .

However, when switching the recording peaking frequency for various tapes, coil L ₁ and capacitor C ₃ or
Series resonance is caused by the combined capacitance of C ₃ and C ₄ , and the recording current characteristics with sharp peaking characteristics as shown in Fig. 5 are obtained, so the coil is abolished and the capacity of the capacitor is reduced due to the Q relationship. This is not possible, which is a factor of cost increase.

The object of the present invention is to use the combination of the combined value of the recording peaking characteristic and the recording current sensitivity corresponding to various tapes, which does not use a coil and which reduces the capacity of the capacitor, which is a factor that increases the cost of the above conventional example. An object of the present invention is to provide a recording amplification circuit of a magnetic recording / reproducing apparatus using a settable operational amplifier.

The present invention relates to a recording / amplifying circuit of a magnetic recording / reproducing apparatus capable of switching a sharp recording peaking characteristic and a recording current sensitivity by switching only a capacitor and a resistor without using a coil. Apply a signal to the non-inverting input terminal, connect the first capacitor to the inverting input terminal, connect the second capacitor to the voltage output terminal, connect the other ends of the first and second capacitors, and A first resistor is provided between the ground and a second resistor that can be connected or disconnected between the coupling point of the capacitor and the ground by the first switch means, and further connected in series between the voltage output terminal and the inverting input terminal. And a second switch means for short-circuiting one of the third and fourth resistors and one of the third and fourth resistors, and a fifth resistor and a third resistor between the inverting input terminal and the ground. Switch means By providing a sixth resistor capable of connecting and disconnecting the inverting input terminal and the ground, the first, second and third switch means are switched to change the characteristics of the output voltage of the operational amplifier, and various tapes are used. It is configured to obtain a recording current curve that is optimal for (normal, chrome, metal tape, etc.).

Description of Embodiments FIG. 2 is a circuit diagram of a recording / amplifying circuit of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

In FIG. 2, the input terminal 1 and the coupling capacitor
C ₁ , C ₂ , bias resistance R ₁ , constant current resistance R ₂ , operational amplifier 3
The + input terminal 4, the output terminal 6 and the head 2 of the operational amplifier 3 have the same configuration as the conventional example.

Between the-input terminal 5 and the output terminal 6 of the operational amplifier 3,
NF resistor R ₇ and NF resistor R ₁₁ are connected in series and their NF
And coupling point 7 of the resistors R ₇ and R _11, the output switch SW4 is provided between the terminal 6 is provided, and a resistor R ₁₁ switch SW4 is closed is adapted to be shorted. Also, -input terminal 5
Between the output terminal 6 and the capacitor C ₅ ,
C ₆ are connected in series, and their points of attachment 8 of the capacitor C _5, C _6, between ground resistor R ₈ and the resistor R ₁₀ to the switch SW6 is connected when in parallel with the resistor R ₈ are closed It is provided. -A resistor R ₆ between the input terminal 5 and ground, and a resistor R ₆ connected in parallel with the resistor R ₆ when the switch SW 5 is closed.
₉ is provided.

Considering the basic circuit of the present invention in which the switch SW4 is closed and the switches SW5 and SW6 are open in the above configuration, the circuit configuration is as shown in FIG. 3, and the gain at this time is And in the low frequency region Is represented by It has sharp peaking characteristics and can obtain the characteristics shown in FIG.

Next, as described in the conventional example, switching of the switches SW4, SW5, SW6 for obtaining the optimum recording current characteristics for various tapes will be described.

In order to obtain the recording current characteristics matched with the normal tape, the switch SW4 is closed and the switches SW5 and SW6 are opened, that is, as described in FIG. 3, and the gain in the low frequency region is And the peaking frequency is Thus, the normal recording current characteristic shown in FIG. 5 is obtained.

Next, in order to obtain the recording current characteristic matched with the chrome tape, the switches SW4 and SW5 are opened and the switch SW6 is closed. Therefore, the gain in the low frequency region is , The gain is higher than normal, and the recording peaking frequency is Next, (R ₇ + R ₁₁ )》 R ₈ R _10
It becomes higher than ₁ and the chrome recording current characteristic shown in FIG. 5 is obtained.

Next, in order to obtain the recording current characteristic matched with the metal tape, the switch SW4 is opened and the switches SW5 and SW6 are closed. The gain in the low frequency range is Is higher than the gain of chrome. The recording peaking frequency is the same as that of chrome. Thus, the recording current characteristics of the metal shown in FIG. 5 can be obtained.

As described above, according to the present embodiment, it is possible to obtain optimum recording current characteristics for various tapes without using a coil only by combining an operational amplifier, a resistor, and a capacitor, and by selecting a constant, The capacity of the capacitor can be easily reduced, and the recording current switching circuit adapted to various tapes can be realized only by combining the combined values of the resistors, so that a very low cost recording amplifier circuit can be provided.

In order to obtain the recording current characteristics matched with the chrome tape, the switch SW4 is opened, and the NF resistance between the −input terminal 5 and the output terminal 6 of the operational amplifier 3 is the combined resistance of the resistances R ₇ + R ₁₁ . The same effect can be obtained by making the NF resistance only the resistance R ₇ , connecting the resistance R ₁₁ and the switch SW 4 in series between the − input terminal and the ground, and closing the switch SW 4.

Further, since the peaking frequencies of the metal tape and the chrome tape are set to be the same in this embodiment, the operational amplifier 3
-Capacitor connected between the input and output terminals
C _5, SW6 for coupling point 8 and the resistance between the ground R ₁₀ and SW6 are connected in series C _6, the metal, chromium during both, between it closed, the point of attachment 8 earth, metal, chrome By setting an independent resistor SW in series with each tape and switching the recording peaking frequency with each tape, more optimal recording current characteristics can be obtained, especially for high-grade tape recorders, etc.
It will be necessary.

The present invention uses an operational amplifier to construct an NF circuit of a non-inverting amplifier circuit as shown in FIG. 2 with only a resistor and a capacitor without using a coil. Only by switching the resistor, a sharp peaking characteristic can be obtained. The optimum recording current characteristics of various tapes can be obtained, and the capacity of the capacitor can be easily reduced by selecting the resistance value. Very low price and compact magnetic recording / reproduction. It is possible to realize the recording amplification circuit of the device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a recording / amplifying circuit of a conventional magnetic recording / reproducing apparatus, FIG. 2 is a circuit diagram of a recording / amplifying circuit of a magnetic recording / reproducing apparatus according to an embodiment of the present invention, and FIG. FIG. 4 is a basic circuit diagram of one embodiment, FIG. 4 is a recording current characteristic diagram of a magnetic recording / reproducing apparatus, and FIG. 5 is a recording current characteristic diagram necessary for normal, chrome, and metal tape. 1 ... Input terminal, 2 ... Head, 3 ... Operational amplifier, 4
...... operational amplifier positive input terminal, 5 ...... operational amplifier - input terminal, an output terminal of the 6 ...... operational amplifier, C ₁ -C ₆ ...... capacitors, R ₁ to R ₁₁ ...... resistance, L ₁ ...... Coil, SW1 to SW6 ...
…switch.

Claims (1)

[Claims] 1. A signal is applied to the non-inverting input terminal of an operational amplifier, a first capacitor is connected to the inverting input terminal, and a second capacitor is connected to the voltage output terminal, and the other ends of the first and second capacitors are connected. And a first resistor between the connection point and ground,
A second resistor is provided which can connect and disconnect the coupling point of the capacitor and the ground by the first switch means, and further has a third and a fourth resistor connected in series between the voltage output terminal and the inverting input terminal. And a second switch means for shorting one of the third and fourth resistances thereof, further comprising a fifth resistor between the inverting input terminal and ground and a third switch means for inverting the input terminal. A sixth resistor that can connect and disconnect between the earth and the ground is provided, the first, second, and third switch means are switched, and the characteristic of the output voltage of the operational amplifier is changed by combining the combined values of the resistors. A recording amplifier circuit of a magnetic recording / reproducing apparatus characterized by being configured to supply a recording current to the head.