JPS633278Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pick-up cartridge, and has a configuration in which a Hall element is provided in the magnetic path in the core to output a signal for controlling tone arm rotation. To provide a pick-up cartridge which can securely detect the cantilever and more reliably hold the cantilever at its optimum operating point, eliminate reproduction distortion, and obtain reproduced sound with a good signal-to-noise ratio.

Generally, when playing a record using a pick-up cartridge, if the record is warped or rotates eccentrically, the cantilever will move significantly up and down and left and right, causing distortion when detecting the originally recorded signal. occurs. This phenomenon also occurs due to the side force acting on the tone arm during record playback. Furthermore, if the tone arm causes low-frequency resonance due to warping of the record, stable signal reproduction becomes impossible.

In order to solve this problem, there is a record player that controls the rotation of the tone arm to maintain a constant distance between the pickup cartridge and the record surface, thereby keeping the cantilever at the optimal operating point. The tone arm control device of this record player has a configuration as shown in FIG. In the figure, a signal picked up from a record disc 2 by a pick-up cartridge 1 is amplified by a preamplifier 3, and is supplied to a speaker 5 via a power amplifier 4 for sound generation. At the same time, the output signal of the preamplifier 3 is supplied to a low frequency amplifier 6, and the low frequency signal component passed through this is passed through a control amplifier 7 to an electro-mechanical coupling section 8.
is supplied to The tone arm 9 is driven by the electro-mechanical coupling section 8 to rotate as appropriate about the fulcrum 9a, and the position of the pickup cartridge 1 is corrected and controlled so that the operating point of the cantilever 1a is at the optimum position.

Here, when a speed amplitude proportional type cartridge such as a moving coil type is used as the cartridge 1, the output voltage at low frequencies is extremely small because the speed amplitude is generally small at low frequencies, and as the frequency increases, the output voltage increases. The voltage increases gradually. In this case, the distortion components caused by warping, eccentric rotation, etc. of the record are extremely low frequency components of 20 Hz or less. Therefore, the conventional record player cartridge coil described above is capable of suppressing extremely low frequencies such as warping and eccentric rotation. The problem was that the output voltage obtained for tone arm control was extremely small, making it practically impossible to control the tone arm.

The present invention eliminates the above drawbacks, and the second
An example will be described below with reference to the drawings.

FIG. 2 shows a schematic configuration of an embodiment of the pick-up cartridge according to the present invention. In the same figure,
A movable magnet 11 to which a cantilever 10 is attached is supported by appropriate members at the tips of cores 12a and 12b. Reference numeral 13 denotes a Hall element, which is sandwiched between the butt portions of the cores 12a and 12b, and a control current is passed through the lead wire 14.

The pick-up cartridge 15 of the present invention is constituted by the above-mentioned parts, and is not provided with a conventional coil.

FIG. 3A shows the cantilever 10 or movable magnet 11 in its optimal operating position. Most of the magnetic flux 11a from the magnet 11 flows as shown by the arrow and does not reach the Hall element 13, and the output voltage from this is approximately zero. Figures B and C show the state in which the cantilever 10 is tilted at an angle θ upward and downward from the optimum operating position, respectively, when the needle of the cantilever 10 traces the sound groove during a record performance. When the cantilever 10 is tilted upward and downward, magnetic flux 11 is generated in the cores 12a and 12b.
b and 11c flow in the direction shown by the arrow, the amount of magnetic flux is proportional to the inclination angle θ, and the directions of the magnetic fluxes are opposite to each other depending on the inclination direction.

Here, when the Hall element 13 is supplied with a constant control current and the control magnetic field B is changed, the Hall element 13 generates a Hall voltage proportional to the control magnetic field B, as shown by the graph line I in FIG. It has the property of producing V. Therefore, a voltage proportional to the inclination angle θ, that is, the displacement amount of the needle tip is extracted from the output lead wire 16 of the Hall element 13.

The pick-up cartridge 15 having the above configuration is as follows:
As shown in FIG. 5, it is incorporated into a tone arm control device. The apparatus shown in this figure is constructed in substantially the same manner as the apparatus shown in FIG. 1, and in the figure, the same components as those shown in FIG.
The explanation will be omitted.

During record playback, the signal recorded on the record disc 2 is extracted as a Hall voltage obtained from the Hall element 13 by the displacement of the cantilever 10 as shown in FIG. The frequency characteristics are corrected, and the sound is output from the speaker 5 via the amplifiers 3 and 4.

On the other hand, the output voltage from the Hall element 13 has middle and high frequency components cut off by a low frequency converter 6 with a cut-off frequency of about 20 Hz, and is supplied to an electro-mechanical coupling section 8 via a control amplifier 7. Rotate and displace 9. Here, since the control signal for rotationally displacing the tone arm 9 has a sufficient SN ratio and a voltage corresponding to the displacement of the cantilever 10 at an extremely low frequency of 20 Hz or less, The tone arm 9 is arranged so that the pick-up cart cartridge 15 is at a predetermined height position with respect to the record 2, that is, the cantilever 10 is arranged so that the cantilever 10 appears to be at a position shown in FIG. 3A.
The rotation is controlled stably to reach the optimum operating position shown in .

Here, the reason why the cutoff frequency of the low frequency converter 6 is set to approximately 20 Hz is that when the tone arm 9 is rotationally controlled, the magnet 11 is apparently kept stationary at the position shown in FIG. 3A. Element 1
According to 3, frequency signal components below the above-mentioned cut-off frequency will not be output, but if the unreproducible frequency is below 20Hz, this will not cause any audible problem, and the frequency of the disturbance that causes playback distortion should be below 20Hz. It is based on

As a result, if the record 2 is warped, the cartridge 15 is controlled to maintain a constant height position from the record 2 surface, and the cantilever 10 and magnet 11 are optimally adjusted according to the recording signal of the record 2. It vibrates and displaces around the operating position. As a result, the recorded signal is distortion-free and has good S/N.
The signal is reproduced as a signal having a ratio, and is output from the speaker 5.

Now, consider a case where the cantilever 10 is displaced at an extremely low speed. For example, the third
When the cantilever 10 as shown in Figure C is displaced from the position shown by the broken line to the position shown by the solid line at an extremely low speed, the direction of the magnetic flux 11c passing through the Hall element 13 does not change, but only the strength of the magnetic field changes. , a Hall voltage of a magnitude corresponding to this amount of change is extracted. Therefore, the displacement of the cantilever 10 at an extremely low speed that could not be detected by the coil in the conventional speed-amplitude proportional pickup cartridge can be reliably detected, and the tone arm can be controlled more reliably than in the conventional one.

As mentioned above, the pick-up cartridge according to the present invention has a Hall element in the magnetic path in the core, and the Hall element outputs a signal to control the rotation of the tone arm. It is possible to reliably obtain a voltage that corresponds to the extremely low-speed displacement of the cantilever, and this makes it possible to detect extremely low-frequency displacements of the cantilever that cannot be detected by the coils of conventional velocity-amplitude proportional pick-up cartridges. It can be detected reliably, the cantilever can be reliably held at the optimum operating point even if the record is warped or eccentrically rotated, and there is no distortion.
It has features such as being able to obtain a reproduced signal with a good signal-to-noise ratio.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a tone arm control device that cooperates with a conventional pickup cartridge, FIG. 2 is a schematic diagram of an embodiment of a pickup cartridge according to the present invention, and FIGS. Fig. 2 is a diagram for explaining the displacement detection operation of the cartridge shown in Fig. 4, Fig. 4 is a control magnetic field versus Hall voltage characteristic diagram of the Hall element, and Fig. 5 is a diagram of the tone arm control device that cooperates with the cartridge shown in Fig. 2. It is a schematic diagram. 2...Record, 6...Low frequency device, 8...
Electrical-mechanical coupling section, 9... Tone arm, 10...
...Cantilever, 11...Movable magnet, 12
a, 12b... Core, 13... Hall element.

Claims (1)

[Scope of utility model registration request] A pick-up cartridge comprising a Hall element provided in a magnetic path within the core, and configured such that the Hall element outputs a signal for controlling rotation of a tone arm.