JPH01236402A - Information signal reproducing device - Google Patents

Abstract

PURPOSE:To realize the sure electrical reduction of the frequency characteristic waves of the reproduced information signal received from a magnetic head by adding this information signal and the outputs of 1st and 2nd level control circuits together by an adder circuit. CONSTITUTION:The reproduced information signal received from a magnetic head is supplied to an adder circuit 3 as well as to 1st and 2nd band pass filters 4 and 5 respectively. Then the outputs of both band pass filters 4 and 5 are supplied to the circuit 3 via the 1st and 2nd level control circuits 7 and 8 respectively and then added with the reproduced information signal received from the magnetic head. As a result, the information signal containing the reduced frequency characteristic waves is obtained from the circuit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for reproducing information signals such as video signals and audio signals.

[Summary of the invention]

The present invention provides an information signal reproducing device in which an information signal recorded on a magnetic tape is reproduced by a magnetic head. consisting of the first and second
first and second bandpass filters having first and second passband center frequencies respectively substantially equal to the frequency of By supplying the signal to the control circuit and adding the reproduced information signal and each output of the first and second level control circuits in the adder circuit, the fluctuation in the frequency characteristics of the reproduced information signal from the magnetic head is reduced. is designed to reliably reduce electrically.

[Conventional technology]

In an audio tape recorder or VTR, when an audio signal is recorded in the longitudinal direction of a magnetic tape and the recorded signal is reproduced, the reproduced audio signal has a low frequency characteristic due to its frequency characteristics, as shown in FIG. 3A, for example. range (for example, 20Hz to 4
00Hz), undulations (or undulations) occur.

This depends on the recording wavelength on the magnetic tape and the shape of the vicinity of the portion of the magnetic head that contacts the magnetic tape. This is called a contour effect.

In this way, if there is a undulation in the low range of the frequency characteristics of the audio or signal reproduced from the magnetic tape by the magnetic head,
When a mask tape is created by repeatedly editing with a commercial audio tape recorder or VTR, the undulations are emphasized and the sound quality of the audio signal is degraded.

Therefore, as a countermeasure against such waviness, there are conventional measures as follows.

(2) The shape of the magnetic head near the part that contacts the magnetic tape is designed to reduce waviness so that the magnetic tape gradually approaches and gradually separates from the magnetic head. An example of this is the Hibabo Fukuhead.

■ An example of increasing the shape of the part of the magnetic head that comes into contact with the magnetic tape to move the frequency of the waviness out of the audible range is the head made by the Swiss company Steube.

(2) An example of a system in which the shape of the magnetic head is continuously changed in the trunk width direction so that various frequency characteristics can be synthesized is found in Victor's X-cut Herad.

In addition, a magnetic head is provided with a shield case in order to avoid deterioration of S/N due to external magnetic induction. The exposed window is widened along the direction of magnetic tape movement to reduce waviness.

■ If method (■) above is not sufficient, in addition, the level of the low frequency of the reproduced signal from the magnetic head is lowered using an electric circuit, thereby lowering the peak of the lowest frequency range and reducing the swell. Reduce.

[Problem to be solved by the invention]

However, all of the conventional countermeasures against waviness involve devising the shape and structure of the magnetic head, which makes manufacturing the magnetic head troublesome and does not allow adjustment.
There may be cases where the optimum conditions cannot be satisfied.

In view of this point, the present invention proposes an information signal reproducing device that can electrically and reliably reduce the fluctuations in the frequency characteristics of the reproduced information signal from the magnetic head.

[Means to solve the problem]

The present invention provides an information signal reproducing device in which an information signal recorded on a magnetic tape is reproduced by a magnetic head. first and second bandpass filters (4), (5) having first and second passband center frequencies substantially equal to the first and second frequencies, respectively;
and its first and second bandpass filters (4), (5
), and has first and second level control circuits (7) and (8) whose respective levels are controlled, and an adder circuit (3). 1 and 2nd band pass filters (4), (5) and addition circuit (3)
The adder circuit (3) adds the reproduced information signal and each output of the first and second level control circuits (7) and (8).

[Effect]

According to the present invention, the reproduced information signal from the magnetic head is supplied to the adder circuit (3) and the first and second band pass filters (4) and (5). Then, each output of the first and second band pass filters (4) and (5) is connected to the first
is supplied to the adder circuit (3) through the second level control circuits (7) and (8), and is added to the reproduced information signal from the magnetic head. A reduced information signal is output.

〔Example〕

An embodiment in which the present invention is applied to an audio tape recorder will be described in detail below with reference to FIG. (1) is an input terminal, and an audio signal reproduced from a magnetic tape by a magnetic head is supplied to this input terminal (1). The frequency characteristic of the reproduced audio signal supplied to this input terminal (1) is, for example, as shown by the solid curve in FIG. 3A (horizontal axis is frequency (logarithm), vertical axis is response (dB)). Suppose it was. In this frequency characteristic curve of Fig. 3A, 7
, F2, and F3 are the maximum, minimum, and maximum of levels that have a large level difference from the flat level, respectively, and their respective frequencies are F1, F2, and Fs (Ft < F2 < F3
) and belongs to the low frequency range.

Therefore, in FIG. 1, band-pass filters (4) whose passband center frequencies are F1, F2, and F3, respectively
, (5), and (6) are provided. FIG. 3B1C and D show examples of bandpass characteristics of these bandpass filters (4), (5), and (6). The horizontal and vertical axes of FIGS. 3B, C, and D are the same as those of FIG. 3A.

In addition, at the next stage of each bandpass filter (4), (5), (6), there are attenuators (fixed attenuator or variable attenuator) (7), (8), (9) as a level control circuit. will be established.

Furthermore, an adder circuit (3) is provided. Then input terminal (1
) is added to the adder circuit (3).

is supplied in positive phase to the bandpass filter (4), (
5) and (6). And a bandpass filter (
4), (5), and (6) are supplied to attenuators (7), (8), and (9), respectively, in order to prevent clipping, and the frequencies of the reproduced audio signals in FIG. 3A are respectively adjusted. Maximum P1 of characteristics
, an appropriate amount of attenuation is set according to the level difference between the minimum P11% and the maximum P3 with respect to the average level. And the attenuator (
7) is supplied to the adder circuit (3) in reverse phase, and the attenuator (
8) is supplied in positive phase to the adder circuit (3), and the attenuator (
9) is supplied to the adder circuit (3) in reverse phase.

(Then, the audio signal output to output terminal (2) is
As shown by the broken line curve in FIG. 3A (it can be seen that the waviness of the solid line curve is reduced).

Next, specific examples of the bandpass filters (4), (5), and (6) in FIG. 1 will be described with reference to FIG. 2. This bandpass filter is a bridged T-type circuit with a small number of components. (10) is an operational amplifier, an input terminal (11) is derived from its non-inverting input terminal, and an output terminal (12) is derived from its output terminal. Operational amplifier (10)
The output terminal of is connected to its inverting input terminal through a resistor (13). Further, a series circuit of capacitors (14) and (15) having the same capacitance is connected to both ends of the resistor (13), and the midpoint of the connection of the capacitors (14) and (15) is connected to the resistor (16). grounded through.

In the above embodiments, the present invention was applied to an audio tape recorder. However, in a VTR, when audio signals are recorded on the side edges of a magnetic tape, or when audio signals are recorded on an inclined track instead of a video signal, The present invention can also be applied to cases such as recording signals.

Further, the number of bandpass filters and corresponding attenuators is arbitrary.

(Effects of the Invention) According to the present invention described above, it is possible to obtain an information signal reproducing device that can electrically and reliably reduce the waviness in the frequency characteristics of the reproduced information signal from the magnetic head.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a bandpass filter thereof, and FIG. 3 is a characteristic curve diagram showing frequency characteristics. (4), (5), and (6) are the bandpass filters, (7
), (8), and (9) are attenuators, respectively, and (3) is an adder circuit.

Claims (1)

[Claims] In an information signal reproducing device in which an information signal recorded on a magnetic tape is reproduced by a magnetic head, the level of the frequency characteristic of the reproduced information signal from the magnetic head is a maximum and a minimum, respectively. first and second bandpass filters having first and second passband center frequencies substantially equal to the first and second frequencies, respectively; and each output of the first and second bandpass filters is It has first and second level control circuits to which respective levels are controlled, and an adder circuit, and the reproduction information signal is sent to the first and second bandpass filters and the adder circuit. and by the adder circuit,
An information signal reproducing device characterized in that the reproduced information signal and each output of the first and second level control circuits are added.