JPS6120201A - Ac erasing circuit - Google Patents

Abstract

PURPOSE:To change the variation of a sound volume to continuous one, by providing a variable impedance circuit which is operable from the outside of the apparatus equipped with the circuit and divides an erasing current supplied from a bias oscillator to an erasing magnetic head. CONSTITUTION:A variable resistor 7 has such a resistance value changing characteristic that, when a recorded tape is loaded and a conducted condition is set by closing a switch 6, the resistance value changes so that the electric current flowing to an erasing head 1 can change within the extention between points A and B and, since the extent between the points A and B is very narrow, the changing quantity of the resistance value against the rotating angle is extremely small. When operations are made to gradually increase the sound volume, the erasing current changes from the point B to the point A, if the erasing operation is made and the variable resistor 7 is changed in the direction, in which the resistance value is damped. In case when the sound value is gradually decreased, the erasing current changes from the point A to the point B, if the erasing operation is made and the variable resistor 7 is changed in the direction, in which the resistance value is increased. Therefore, the recorded condition of magnetic tapes, on which sounds are interrupted in the course of recording or recording is performed from the midway, can be corrected in such a way that the recording is performed by gradually changing the sound value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an AC erasure circuit in tape recorder equipment.

Conventional configurations and their problems In general, when tape recorder equipment records signals onto magnetic tape, the desired recording signal is
This is done by passing a bias current that is superimposed on the bias current that normally flows through the recording magnetic head, and the volume of the sound produced by this recorded signal (hereinafter referred to as "playback sound") during tape playback is determined by the "volume". '') is adjusted depending on the magnitude of the recording signal current applied to the recording magnetic head during recording.

On the other hand, in the erasing circuit for erasing recorded signals, the erasing current applied to the erasing magnetic head is adjusted to the optimum value during device manufacturing and is then fixed; it cannot be controlled from outside the device. The configuration is such that it is impossible to do so.

Therefore, the volume of the reproduced sound mentioned above is determined only by the operation during recording, and it is impossible to control this again after recording.

For this reason, for example, if the signal being recorded suddenly stops, or if the magnetic tape stops running during recording, the signal in the reproduced sound will also suddenly stop. Also, if you start recording a signal in the middle of a continuous signal, that signal will appear as a sudden output in the playback sound.

These things give an unnatural aural sensation to the user of the device.

However, in order to eliminate such unnaturalness and obtain a reproduced sound in which the volume gradually increases or decreases, as mentioned above, when recording in advance, it is necessary to adjust the magnitude of the recording signal current. There is no other way than to continuously vary the signal and record it while controlling it so that the signal gradually increases or decreases, and this has no effect on already recorded magnetic tape.

OBJECT OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional art.It is an object of the present invention to make changes in volume continuous even for recorded magnetic tapes having discontinuous signals in volume by operation from outside the device. The purpose of the present invention is to provide an AC cancellation circuit that can be changed to

Configuration of the Invention In order to achieve the above object, the AC erasing circuit of the present invention is configured to include a variable impedance circuit that can be operated from outside the device and shunts the erasing current supplied from the bias oscillator to the erasing magnetic head. It is something.

According to this configuration, the erasing effect on the signal can be continuously controlled by changing the impedance of the variable impedance circuit from outside the device and controlling the erasing current flowing through the erasing magnetic head. By using this in conjunction with the erasing operation, even on a recorded magnetic tape that has a part where the volume of the reproduced sound changes discontinuously, it can be used after recording to make that part a continuous change in volume. It becomes possible to operate.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an AC erasing circuit according to an embodiment of the present invention, in which (1) is an erasing magnetic head, (2) is a resonance capacitor, (3) is an oscillation coil, (4) is an oscillation circuit, (5
) is a semi-fixed resistor for adjusting the power supply voltage, (6) is a switch, and (7) is a variable resistor. The erasing magnetic head (
1) A variable resistor (
7) and a switch (6) for opening and closing the same are configured so that they can be operated from outside the device, and the switch (6) is open during normal operation.

FIG. 2 is an explanatory diagram of the relationship between erasing current and erasing effect,
As the erasing current increases to the right of the coordinate, the amount of noise to the signal decreases, thus showing how the erasing effect increases towards the bottom of the coordinate.

In this figure 2, in the range where the erase current is to the left of A, no erasing effect is obtained, and in the range to the right of B, a certain erasing effect is obtained, which is the normal operating state, that is, the switch (6) is open. In this state, an erase current flows in a range to the right of this B. In this embodiment, a portion where the erasing effect changes continuously, that is, a range where the erasing current is between A and B is used.

Next, the operation will be explained. First, a recorded tape is attached to the device, and the switch (6) is closed to make it conductive.

At this time, the variable resistor (7) has a resistance value change such that the erase current flowing to the erase head (1) changes between A and B in FIG. Since the range between 2 and 3 is extremely narrow, the resistance value has a change characteristic such that the amount of change in resistance value with respect to the rotation angle is minute. When performing an operation in which the volume is gradually increased, the device is turned on and at the same time the variable resistor (7) is changed in a direction in which its resistance value is attenuated. At this time, the erase current changes from B to A in Figure 2.
It will change to. On the other hand, if you want to gradually decrease the volume, do the same thing, and at the same time turn off the device,
The variable resistor (7) is changed in a direction in which its resistance value increases. At this time, the erase current changes from A to B in FIG.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, it is possible to perform recordings in which the volume gradually changes even on magnetic tapes on which recordings are made such that the sound cuts out or starts midway during recording. It becomes possible to improve the same magnetic tape after recording, making it possible for the user to perform recording, editing, etc. using the equipment more comfortably.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an AC erasing circuit according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the relationship between erasing current and erasing effect of the AC erasing circuit. (1)...magnetic head for erasing, (4)...oscillation circuit,
(6)...Switch, (7)...Variable resistor agent Yoshihiro Morimoto Ward 1? figure

Claims (1)

[Claims] 1. An AC erasing circuit that can be operated from outside the device and includes a variable impedance circuit that shunts the erasing current supplied from the bias oscillator to the erasing magnetic head.