JPS6334400Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the magnetic circuit of a moving coil type pickup cartridge.

As shown in Fig. 1, the structure of an example of a conventional moving coil type pickup cartridge includes a front panel made of pure iron or a magnetic material with a high saturation magnetic flux density, with a field magnet 2 sandwiched between a base 1 and a magnetic material having a high saturation magnetic flux density. In a magnetic circuit including a yoke 3 and a rear yoke 4 and a pole piece 5, an armature 8 having a cantilever 6 fixed thereon and an excitation coil 7 wound thereon is inserted into the magnetic gap between the front yoke 3 and the pole piece 5 via a damper 9. The structure is arranged in such a way that In such a configuration, the vibration of the styler 10 due to record reproduction propagates through the cantilever 6 and causes the armature 8 to vibrate, thereby changing the amount of magnetic flux interlinking the excitation coil 7 wound around the armature 8 in the magnetic gap. Terminal 1 due to the power generation action of excitation coil 7
Output from 1. By the way, the inventor's research revealed that in such a magnetic circuit, a peculiar phenomenon caused by armature vibration occurs, which affects the minute playback output current and causes the deterioration of playback sound quality. I was able to confirm it. That is, the vibration of the armature made of a magnetic material with high magnetic permeability changes the direction and amount of magnetic flux flowing through the armature as shown in FIG. 2, and the amount of magnetic flux flowing through the entire magnetic circuit changes in accordance with the audio signal.
As a result, a minute back electromotive current 12 is generated on the surface of the front yoke or rear yoke, which flows through the surface of the magnetic circuit including the front yoke, excitation magnet, and rear yoke, causing minute distortion of the reproduction output current. be. As a result, the sound quality suffers from a decrease in delicateness in the high range, a deterioration in the clarity of pitch in the mid range, and a deterioration in the response in the low range.

In consideration of this point, it is an object of the present invention to provide a magnetic circuit structure for a pickup cartridge that reduces reproduction distortion by eliminating back electromotive current generated in the magnetic circuit.

Next, the present invention will be explained with reference to the drawings. The present invention provides magnetic and electrical insulation by creating a minute gap between each component in the magnetic circuit formed by the front yoke, field magnet, and rear yoke components of a moving coil type pickup cartridge. It is a structure that prevents the back electromotive current 12 generated on the surface of each component from flowing through the entire magnetic circuit, and furthermore, it is designed to electrically short-circuit a specific position between each component that forms a gap, and furthermore, the magnetic circuit is It is also effective to remove the back electromotive current generated in the magnetic circuit by connecting the upper point to the ground side of the terminal. In the present invention, it is preferable to limit the distance between the magnetic gaps to 100 μm or less, but this is the upper limit that does not reduce the permeance of the magnetic circuit, and it is possible to form the magnetic gaps by sandwiching an insulator such as Mylar film. be done. Third
Figures a and b show examples of this, and in both figures, the magnetic circuit section is more electrically non-conductive than the head shell, pickup, or tone arm, but in a, there is a magnetic gap 1 between the front yoke and the field magnet.
3 is provided to connect the front yoke and rear yoke with a lead wire 14, and is further wired to the ground side of the terminal, and b is a magnetic gap 13 between the front yoke and the field magnet and between the field magnet and the rear yoke, respectively. , 13' are provided, and a lead wire 14' connects the front yoke, rear yoke, and field magnet, and is further wired to the ground side of the terminal. As a result of this structure, the distortion of the reproduced output current due to the back electromotive current was removed, the transient response was improved, and the sound quality in the high, mid and low ranges was improved.

[Brief explanation of the drawing]

Figure 1 is a structural diagram of a conventional pick-up cartridge. Figure 2 is a state diagram of the magnetic circuit. FIG. 3 is a structural diagram showing an embodiment of the present invention. 1: Base, 2: Field magnet, 3: Front yoke, 4: Rear yoke, 5: Pole piece,
6: cantilever, 7: excitation coil, 8: armature, 9: damper, 10: stylus, 1
1: Terminal, 12: Back electromotive current, 13,1
3': Magnetic gap, 14, 14': Lead wire.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In the magnetic circuit of a moving coil type pick-up cartridge formed of a front yoke, field magnet, rear yoke, pole piece, etc., between the front yoke and rear yoke that are in contact with the magnetic pole of the field magnet. A magnetic circuit for a pick-up cartridge, characterized in that a magnetic gap is provided in at least one side of the magnetic circuit. (2) The magnetic circuit of the pick-up cartridge according to claim (1) of the utility model registration, in which the gap is electrically short-circuited.