JPS6034098Y2 - Recording frequency characteristic correction device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a recording frequency characteristic correction circuit that can arbitrarily vary the recording frequency characteristic of a tape recorder or the like.

N of tape recorders, etc., which have traditionally been most widely used.
AB! A recording frequency characteristic correction circuit for adjusting the tI characteristics or performing pre-emphasis is shown in FIG.

In FIG. 1, the amplifier for correcting frequency characteristics is a common emitter amplifier circuit having one transistor.

A load resistor 12 is connected to the collector of the transistor 10, and the collector is connected to a power source via the load resistor 12.

Further, a coupling capacitor 14 is connected to the collector, and the output signal of the amplifier is supplied through the coupling capacitor 14 to a recording magnetic head of a recorder (not shown) directly or via a resistor, a trap circuit, etc.

On the other hand, the emitter of the transistor 10 is connected to the emitter resistor 16.
A resonant circuit 18 is connected in parallel to this emitter resistor 16.

The resonant circuit 18 is a series circuit of a variable inductance 20 forming an inductance circuit and a capacitor 22 forming a capacitor circuit.

The amplifier inputs an audio signal etc. from the base of the transistor 10 and amplifies the voltage, but since the emitter resistor is connected in parallel with a resonant circuit 18 consisting of a series circuit of a variable inductance 20 and a capacitor 22, the resonant frequency can be adjusted to a desired value. By setting the emitter current flowing through the emitter resistor 16 to a high frequency, it is possible to increase the voltage amplification gain of the amplifier.

However, according to the conventional example described above, there are many difficulties in digitally controlling the capacitor capacitance of the capacitor circuit using a microcomputer, etc., or remotely controlling it using an external device, especially if the accuracy is low. I have no choice but to.

The present invention has been devised in view of the above-mentioned conventional problems, and its purpose is to provide a recording frequency characteristic correction device capable of stably and accurately controlling the correction of recording frequency characteristics in steps using digital control signals. It is in.

In order to achieve the above object, the present invention provides a recording frequency characteristic correction device that increases and corrects the gain in the high range of the audio frequency band by providing a resonant circuit including an inductance circuit and a capacitor circuit in the feedback circuit of the amplifier. The capacitor circuit of the resonant circuit includes a circuit in which a plurality of series circuits of fixed capacitors and switches are connected in parallel, and the capacitance of the capacitor circuit is controlled in steps by controlling the switch by an external switch control signal. Features.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a preferred embodiment of the invention.

What differs from the conventional example shown in FIG. 1 is the capacitor circuit 22.

The capacitor circuit 22 includes each capacitor 22-1.
There are 4 series circuits in which 22-4 and the corresponding switch transistors 24-1 to 24-4 are connected in series.
2 are connected in parallel, and a variable capacitor 26 is connected in parallel thereto.

The base of the switching transistor 24 is connected to an output terminal of a control device (not shown) that outputs a digital control signal.

Also in the present invention, the resonant frequency of the resonant circuit 18 is determined by the inductance of the variable inductance 20 and the capacitor circuit 2.
It is determined by the capacitor capacity of 2.

However, in the present invention, the capacitor circuit 22
The capacitance of the switching transistor 24 is determined by a digital control signal from an external control device (not shown).
-1 to 24-4 are turned on and off to perform step control.

That is, the capacitor circuit 22 is the sum of the capacitor capacitances of the capacitors 22-1 to 22-4 of the switching transistors 24-1 to 24-4 turned on by an external digital control signal and the capacitor capacitance of the variable capacitor 26.
The capacitor capacity will be .

As a result, the capacitor capacitance of the capacitor circuit 22 is step-controlled by the digital control signal from the external control device, and it becomes possible to obtain a recording frequency characteristic correction device that can correct the recording frequency characteristics to a desired recording frequency characteristic.

As explained above, according to the present invention, correction of recording frequency characteristics can be controlled stably and accurately using a circuit with a simple configuration.

According to the present invention, the capacitor capacity of the capacitor circuit can be digitally controlled by a microcomputer or the like or remotely controlled using an external device.

Furthermore, since the value of the capacitor capacitance of the capacitor circuit can be determined by arbitrary combinations or selections, it is also possible to obtain various frequency characteristics.

In particular, according to the present invention, the capacitance of the capacitor circuit, which is switched and controlled in a stepwise manner, can be further finely adjusted by using a variable capacitor to accurately correct the recording frequency characteristics.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional recording frequency characteristic correction device.
FIG. 2 is a circuit diagram showing a preferred embodiment of the recording frequency characteristic correction device according to the present invention. In each figure, the same members are given the same reference numerals, 22 is a capacitor circuit, 24 is a switching transistor, and 26 is a variable capacitor.

Claims (1)

[Scope of Claim for Utility Model Registration] A recording frequency characteristic correction device that increases and corrects the gain in the high range of the audio frequency band by providing a resonant circuit including an inductance circuit and a capacitor circuit in the feedback circuit of an amplifier, comprising: A capacitor circuit consists of a circuit in which multiple series circuits of fixed capacitors and switches are connected in parallel, and a circuit in which a variable capacitor is connected in parallel to this circuit.
, wherein the switch is controlled by an external switch control signal to step-control the capacitance of the capacitor circuit, and finely adjusts the capacitance of the capacitor circuit by controlling the variable capacitor. Recording frequency characteristic correction device.