JPS5843696A - Demagnetizing method of cartridge and its device - Google Patents

Abstract

PURPOSE:To erase residual magnetism which remains in a magnetic material core, and to eliminate distortion in case of reproduction, by applying an AC signal of prescribed frequency for a prescribed time, to a power genrating coil of a cartridge, and after that, gradually attenuating its signal to a zero level. CONSTITUTION:To a power generating coil 8 of a cartridge having a magnetic material core, a constant-current output amplifier is connected, and the impedance to the coil 8 is matched. On the input side of this amplifier, an attenuating means 4 using an FET, and an AC signal applying means 3 are provided, bias voltage of the FET of this attenuating means 4 is controlled by charging voltage of a capacitor 5 connected to a switch 6, and the FET is shifted to a cut-off state from a conducting state in accordance with an operation of the switch 6. Subsequently, an AC signal of prescribed frequency from the means 3 is applied to the coil 8 for a prescribed time, and after that, the AC signal is gradually attenuated to a zero level by the attenuating means 4, residual magnetism of the magnetic material core is erased, and distortion of a reproduced sound due to the residual magnetism is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for demagnetizing a cartridge.

In general, a cartridge in which the core of the generating coil is made of a magnetic material such as permalloy, for example, a moving magnet type cartridge in which a generating coil 12, 12 is wound around a core 11 made of a magnetic material as shown in FIG. As shown in Fig. 2, the generator coil 22 is wound around a coil bobbin 21 made of a magnetic material, and then assembled. It is known that residual magnetism remains.

This residual magnetism causes distortion during reproduction and is a factor that significantly reduces the fidelity of reproduction. Therefore, there has been a strong demand for erasing residual magnetism remaining in the magnetic core.

However, to date, no concrete measures have been taken to cancel the residual magnetism of the magnetic core.

The present invention has been made in view of the above circumstances, and after passing an alternating current signal through a power generating coil having a magnetic core for a predetermined period of time, the signal is gradually attenuated to zero level. The present invention provides a method for demagnetizing a cartridge by which residual magnetism remaining in the magnetic core of a generating coil of a cartridge can be erased, and a demagnetizing device for a cartridge for carrying out this method.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, and a degaussing method will also be explained based on a cartridge degaussing device.

FIG. 6 is a schematic configuration diagram showing an embodiment of the device of the present invention. In this figure, reference numeral 6 denotes a means for supplying an alternating current signal of a predetermined frequency to the power generation coil 8, and as this means, for example, an alternating current signal oscillator or an alternating current power source of a predetermined frequency is used.

It should be noted that the predetermined frequency here refers to a frequency sufficient to disturb the arrangement direction of the atomic magnets in the magnetized core, and according to the experimental data of the present inventor, a frequency of about several hundred H2 to several KH2 is desirable. . Further, according to the experimental data of the present invention, it has also been found that it is effective to set the energization time by the energizing means 6 to be approximately 1 second or more. 4 uses a field effect transistor as an attenuation means, and by turning on a switch 6 and controlling the bias voltage of the transistor ladder by the charging voltage of the capacitor 5, the transistor is cut from a conductive state over time. The AC signal supplied to the generator coil 8 is gradually attenuated to zero level as shown in FIG. 4 by shifting to the OFF state. 7 is a constant current output amplifier, which is used as necessary. When using such a constant current output amplifier 7, it is possible to use a moving magnet type force cartridge or -1, -agyoi, which uses a magnetic material for the core material, which is efficient for cartridges with different impedances.

In the type cartridge, residual magnetism in the core material can be effectively removed, and distortion in reproduced sound caused by such residual magnetism can be eliminated very easily.

In addition, this device can also be used built into the player.
Alternatively, it can be sold alone as a cartridge eraser. Further, the AC signal energizing means may be one that utilizes damped vibration of an LC resonant circuit, for example, and in this case, the damping means can also be used in common.

Zara 1 ~ Sea 1, the frequency of the AC signal that should be energized to the generator coil is
Even normal commercial frequencies can be demagnetized.

[Brief explanation of drawings]

1 and 2 are diagrams showing configuration examples of a moving magnet type cartridge and a moving coil type cartridge, respectively, FIG. 3 is a schematic configuration diagram showing an embodiment of the cartridge degaussing device of the present invention, and FIG. 4 is a diagram showing the configuration of a cartridge. It is a waveform diagram of an alternating current signal supplied to a power generation coil. 11.21...Magnetic core, 8, 12.22...
Generator coil, 6... AC signal energizing means, 4... Attenuation means. Figure 1 Figure 2 7.7., 21', No.

Claims (1)

[Claims] 1 (1) An alternating current signal of a predetermined frequency is energized for a predetermined period of time to a generator coil of a cartridge having a magnetic core, and then the alternating current signal is gradually attenuated to a zero level,
A method for demagnetizing a cartridge, characterized by erasing residual magnetism remaining in a magnetic core of the cartridge. (2) AC signal energizing means for energizing an AC signal of a predetermined frequency to a generator coil of a cartridge having a magnetic core;
A cartridge degaussing device comprising attenuating means for gradually attenuating the alternating current signal energized by the alternating current signal energizing means.