JPH06223305A - Recording equalizing circuit and voice magnetic recorder - Google Patents

Abstract

PURPOSE:To provide a recording equalizer circuit easy to adjust with a circuit scale and the size thereof smaller and a voice magnetic recorder having the circuit. CONSTITUTION:A resistance circuit which contains resistances R1', R1'' and R1''' as feedback resistance of a recording amplifier 1 and an amplification characteristic setting circuit 2 which has capacitors C1 and C2 to determine amplification characteristics of the recording amplifier 1 are provided as peripheral circuit of the recording amplifier 1. A resistance value of the feedback resistance of the recording amplifier 1 is changed over with switches SW1 and SW2 according to difference of recording characteristic pertaining to a magnetic tape 5 thereby allowing the changing of the amplification characteristics of the recording amplifier 1. This eliminates the use of a conventional coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording equalizer circuit and a voice magnetic recording apparatus, and more particularly, when a signal is recorded on a recording medium, the recording signal is partially emphasized / suppressed in accordance with the recording characteristics of the recording medium. And a voice magnetic recording device such as a VTR or a tape recorder having this circuit.

[0002]

2. Description of the Related Art Generally, a VTR has a recording equalizer circuit (hereinafter referred to as an equalizer) in a recording circuit. This circuit is for coping with the fluctuation of the recording characteristics due to the magnetic characteristics of the magnetic tape, which is the recording medium, and for realizing a good recording state. Specifically, with respect to an amplification characteristic having a peak corresponding to a frequency range in which it is difficult to record the frequency-gain relationship, the frequency portion is particularly emphasized before recording. The recording characteristics of the recording medium also change depending on the running speed of the magnetic tape and the like. For this reason, in a VTR having three types of speed modes, which are usually called SP, LP, and EP, the amplification characteristic of the equalizer has three characteristics having peaks at different frequencies corresponding to this.

FIG. 8 shows an example of such amplification characteristics. The horizontal axis represents frequency and the vertical axis represents amplification gain, and respective characteristic graphs are shown with the same symbols as the corresponding speed modes. Since the amplification characteristics differ according to the speed mode difference, an equalizer whose amplification characteristics can be switched according to the speed mode switching is used. FIG. 9 shows a conventional circuit of such an equalizer. Here, 1 is a recording amplifier that amplifies the input signal Vi with a predetermined amplification characteristic to generate an output signal Vo, and 2 is a peripheral circuit connected to the recording amplifier 1, which is an amplifier of the recording amplifier 1. It is an amplification characteristic setting circuit that determines the characteristic. This equalizer is a general circuit using an LCR series resonance circuit for its amplification characteristic setting circuit.

FIG. 10 shows a circuit of another structure of the conventional equalizer. This is equivalent to the amplification characteristic setting circuit L
This is a circuit using a CR series resonance circuit, in which the function of the circuit including the inductance element (see the one-dot chain line part) is replaced with an equivalent circuit (simulated inductor) that does not use a coil. It is being adopted because it is advantageous in terms of cost and size. With these equalizers,
By changing the capacitor capacity in the amplification characteristic setting circuit, different amplification characteristics according to the speed mode are obtained.

[0005]

As described above, the conventional equalizer uses the LCR series resonance circuit or the equivalent LCR series resonance circuit as the amplification characteristic setting circuit. But LC
When the R series resonance circuit is used, a coil is used as an inductance element, which causes inconveniences such as high cost, large size, and a tendency to generate inductive noise.

On the other hand, when the equivalent LCR series resonance circuit is used, although the above-mentioned inconvenience is not caused by the non-use of the coil, a simulated inductor is used, so that the circuit scale is increased and a predetermined structure is required. It is difficult to adjust the peak to the frequency of 1), and a large number of pins are required to form an IC. An object of the present invention is to solve the above problems of the prior art, and to realize a recording equalizer circuit which has a small circuit size and size and is easy to adjust, and an audio magnetic recording apparatus having this circuit. Especially.

[0007]

The structure of the recording equalizer circuit of the present invention which achieves the above object is such that an input signal having an amplification characteristic corresponding to a recording characteristic relating to a recording medium having different characteristics depending on magnetic characteristics, tape speed, etc. In a recording equalizer circuit having an amplifier that amplifies an output signal to be recorded on the recording medium, the recording equalizer circuit is provided as a peripheral circuit of the amplifier, and is connected to the resistance circuit including a feedback resistance of the amplifier and the resistance circuit. And an amplification characteristic setting circuit that determines the amplification characteristic of the amplifier by these circuits, and the amplification characteristic setting is performed by switching the resistance value of the feedback resistor according to the difference in the recording characteristic. The amplification characteristic defined by the circuit can be switched.

Further, the structure of the audio magnetic recording apparatus of the present invention which achieves the above object is provided with the above-mentioned recording equalizer circuit, wherein an acoustic signal such as a sound is used as an input signal of the amplifier and an output signal of the amplifier is used. Is recorded on a magnetic recording medium as the recording medium.

[0009]

In the recording equalizer circuit and the audio magnetic recording apparatus of the present invention having such a configuration, the amplification characteristic is determined by the resistance circuit and the capacitor. Therefore, the inductance element is not used. As a result, inconveniences such as an increase in size can be avoided. Also, simulated inductors are not used. As a result, inconveniences such as an increase in circuit scale can be avoided. The switching of the amplification characteristic is performed by switching the resistance value which can be easily adjusted. This facilitates adjustment such as matching the peak of the amplification characteristic to a predetermined frequency. Therefore, the circuit scale and size are small, and the adjustment can be easily performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a VTR as an embodiment of the audio magnetic recording apparatus of the present invention. (A) is a block diagram centering on the audio recording circuit, and (b) is a circuit diagram of the equalizer, that is, a recording equalizer circuit. Further, (c) shows a graph of three amplification characteristics having peaks at different frequencies, with the horizontal axis representing frequency and the vertical axis representing amplification gain. Here, 1 is a recording amplifier that amplifies the input signal Vi with a predetermined amplification characteristic to generate an output signal Vo, and 2 is a peripheral circuit connected to the recording amplifier 1, which is an amplifier of the recording amplifier 1. It is an amplification characteristic setting circuit that determines the characteristic. Further, 3 is a bias oscillation circuit for generating a bias oscillation signal superimposed on the output signal Vo, 4 is an audio head for converting the output signal Vo carrying the bias oscillation signal into a magnetic signal, and 5 is a magnetic tape as a recording medium. is there.

The equalizer (see FIG. 1B) is an amplifier circuit which comprises a recording amplifier 1 and an amplification characteristic setting circuit 2 and whose amplification characteristic can be switched. Amplification characteristic setting circuit 2
Has a resistance circuit in which resistors R1 ', R1 ", R1'" are connected in series, and this resistance circuit is connected to the recording amplifier 1 as a feedback resistance of the recording amplifier 1. Switches SW1 and SW2 are respectively connected to connection points in the resistance circuit, and the resistance value of the resistance circuit is determined according to the open / closed state of the switches SW1 and SW2, as described later. Further, the amplification characteristic setting circuit 2 also includes capacitors C1, C2, resistors R2, R2 ', etc. provided in parallel with this resistance circuit, and this circuit allows the amplification characteristic of the equalizer to have a peak characteristic at a predetermined frequency. Has been added.
As a result, the emphasis process is applied to the frequency range.

The amplification characteristic of the equalizer will be specifically described. The control signals for the switches SW1 and SW2 and the control circuit are not shown. When the recording mode of the VTR, that is, the tape speed is the so-called SP mode, the switch S
W1 is turned on, and the value of the feedback resistor takes a small value (R1 ') due to only the resistor R1'. As a result, the peak of the amplification characteristic at this time has a low maximum value on the high frequency side (see the graph SP of FIG. 1C). This is a characteristic suitable for recording in the SP mode.

On the other hand, when the recording mode of the VTR, that is, the tape speed is the so-called EP mode, the switch SW1 is turned off and the value of the feedback resistance is a large value due to the resistance R1 ', the resistance R1 "and the resistance R1'". (R1 '+ R1 "+ R
1 '"), which means that the peak of the amplification characteristic at this time has the highest maximum value at the low frequency side (see graph EP in Fig. 1 (c)). This is suitable for recording in EP mode. Further, in the intermediate LP mode, only the switch SW2 is turned on, and the value of the feedback resistance and the amplification characteristic are intermediate between those in the above two modes (see the graph LP of FIG. 1C). These are the characteristics suitable for recording in the LP mode.These characteristics change the amplification characteristic by switching the value of the resistor whose characteristic is stable compared to the capacitor or coil, so that the peak position etc. Adjustment is easy.

Other examples of the structure of the equalizer are shown in FIGS. In the circuit of FIG. 2, one of the switches SW3 is opened, so that the characteristic of the high frequency region labeled with “FLAT” in FIG. 1C is different from that of FIG. 1B. The circuit of FIG. 3 is the "FLAT" of FIG. 1 (c).
This circuit differs from the circuit of FIG. 1B having the switching function in that it does not have the characteristic switching function in the high frequency region of the section. The circuit of FIG. 4 differs from the circuit of FIG. 1B which is a non-inverting amplification type in that it is an inverting amplification type. In all of these, the amplification characteristic setting circuit includes a resistor, a capacitor, and a switch, and does not include a simulated inductor or a coil, so that the circuit scale and size can be small.

Further, in order to clarify the relationship between the circuit configuration and its amplification characteristic, a pair of a circuit having a basic configuration excluding the resistance value switching function and its characteristic graph is shown in FIGS. In each drawing, (a) is a circuit configuration and (b) is a graph of the amplification characteristic of the circuit. FIG. 5 shows FIG. 1 (b).
The case of the circuit of the basic configuration corresponding to is shown. 6 is shown in FIG.
In the case of a circuit in which the gain on the low frequency side is somewhat increased with respect to the basic configuration of. FIG. 7 shows a case of an inverting amplification type circuit, whereas the circuit of FIG. 5 is a non-inverting amplification type circuit.

The audio recording circuit of the VTR having the equalizers (1, 2) uses an acoustic signal composed of audio or the like as the input signal Vi of the equalizer, and SP or any other selected tape running mode. The output signal Vo of the equalizer in which a specific frequency range is emphasized / suppressed is obtained. Then, the oscillation signal from the bias oscillation circuit 3 is superimposed on this, and further converted into a magnetic signal by the audio head 4. Finally, the acoustic signal becomes this magnetic signal,
It is recorded in the best condition on an audio track of a magnetic tape which is a magnetic recording medium (see FIG. 1A).

Although the VTR has been described as a specific example, the present invention is not limited to this. The present invention can be applied to a tape recorder and other audio magnetic recording devices, and a graphic equalizer and other recording equalizer circuits, and the same effects can be exhibited. If a transistor circuit such as an analog switch is used as the switch, most circuits other than the capacitor can be integrated into an IC.

[0018]

As can be understood from the above description, in the present invention, the amplification characteristic setting circuit having the resistance circuit including the feedback resistance of the amplifier and the capacitor to determine the amplification characteristic of the amplifier is It is provided as a peripheral circuit. Then, the amplification value of the amplifier is switched by switching the resistance value of the feedback resistor according to the difference in the recording characteristics. As a result, it is possible to obtain an effect that the circuit scale and size are small and the adjustment is easy.

[Brief description of drawings]

FIG. 1 shows a VTR as an embodiment of an audio magnetic recording apparatus of the present invention. (A) is a block diagram centering on the audio recording circuit. (B) is a circuit diagram of the equalizer. (C) is a graph of three amplification characteristics having peaks at different frequencies with the horizontal axis taken as frequency and the vertical axis taken as amplification gain.

FIG. 2 is a second example of the equalizer, which has different characteristics in a high frequency range.

FIG. 3 is a third example of an equalizer, which is an inverting amplification type.

FIG. 4 is a fourth example of an equalizer, which does not have a switching function of high frequency range characteristics.

5A is a circuit diagram of a basic configuration of an equalizer, and FIG. 5B is a characteristic graph thereof.

FIG. 6 is a circuit diagram of an equalizer in which the gain on the low frequency side is somewhat increased, and FIG. 6B is a characteristic graph thereof.

7A is a circuit diagram of an inverting amplification type equalizer, and FIG. 7B is a characteristic graph thereof.

FIG. 8 is a diagram showing three types of amplification characteristic graphs corresponding to tape speed modes of SP, LP, and EP.

FIG. 9 is an example of a conventional equalizer, in which an LCR series resonance circuit is used for its amplification characteristic setting circuit.

FIG. 10 is another example of a conventional equalizer, in which an equivalent LCR series resonance circuit is used for its amplification characteristic setting circuit.

[Explanation of symbols]

 1 recording amplifier 2 amplification characteristic setting circuit 3 bias oscillation circuit 4 audio head 5 magnetic tape

Claims (2)

[Claims] 1. A recording equalizer circuit having an amplifier that amplifies an input signal with an amplification characteristic according to a recording characteristic of a recording medium to generate an output signal for recording on the recording medium, and is provided as a peripheral circuit of the amplifier. And a resistance circuit including a feedback resistance of the amplifier and a capacitor connected to the resistance circuit, and an amplification characteristic setting circuit that determines the amplification characteristic of the amplifier by these circuits is provided. A recording equalizer circuit is characterized in that the amplification characteristic determined by the amplification characteristic setting circuit is switched by switching the resistance value of the feedback resistor. 2. A recording equalizer circuit according to claim 1, wherein an acoustic signal composed of voice or the like is used as an input signal of the amplifier, and an output signal of the amplifier is recorded on a magnetic recording medium as the recording medium. Characteristic audio magnetic recording device.