JPS5845274B2 - Electromagnetic brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic brake device that can rapidly and smoothly stop the rotation of a turntable or the like of a record player.

There are various rotary drive systems for record players, such as a single idler system, a belt drive system, and a direct drive system, but the direct drive system is superior in terms of wow and flutter, S/N1 drift, and the like.

However, in the case of the direct drive system, since the braking force of the motor itself is weak, it has the disadvantage that the time from the stop of power supply to the motor to the stop of rotation of the turntable is long.

Therefore, in a direct drive type record player, it is necessary to forcibly stop the rotation of the turntable, and various methods have been proposed for this purpose.

For example, as a conventional forced braking device, one using a timer has been proposed.

This is to forcibly stop the turntable by energizing the stator coil in reverse phase for a predetermined time using a timer, but due to the load, the brake is turned off before the turntable stops rotating. However, even when the turntable has stopped, the brake continues to work, causing the turntable to rotate in the opposite direction.

In order to improve the above-mentioned drawbacks, it has been proposed in the past to apply a forced brake using the timer for a predetermined period of time, and then use a mechanical brake such as a plunger to stop the rotation of the turntable.

However, such a brake device requires two types of brakes: an electric type and a mechanical type.
It had the disadvantage of generating noise when using a mechanical brake.

The present invention has been made in view of the various points mentioned above, and will be described below based on embodiments and with reference to the drawings.

FIG. 1 is a plan view of a record player using the present invention, in which 1 is a turntable, 2 is an annular rotor arranged on the outer circumferential surface of the turntable 1 and has north and south poles arranged alternately, and 3 is a turntable. A stator 4 is used to drive the rotor 2, and a pickup coil 4 is used to detect the rotational speed of the rotor 2.

The rotor 2 is driven by a stator 3 and controlled by a signal from a pickup coil 4, so that the turntable 1 rotates at a predetermined number of rotations.The details will be explained based on the circuit shown in FIG.

In FIG. 2, 5, 6, and 7 are stator coils arranged in a three-phase relationship with each other; 8, 9, and 10 are drive circuits for driving the stators 5, 6, and 1, respectively;
Reference numeral 1 denotes an oscillation circuit serving as a drive signal source for the stator coils 5.6 and 7; 12.13 and 14 modulation circuits for creating modulation signals having a three-phase relationship with each other from the output signals of the oscillation circuit 11; 15. 16 and 17 are the modulation circuits 12 and 13;
and a detection diode for detecting the 14 output signals,
18 is a pickup coil for generating a signal according to the rotational speed of the rotor 2; 19 is the pickup coil 18;
This is an amplifier circuit that amplifies the output signal of and generates a control signal for controlling the oscillation circuit 11.

Thus, the turntable 1 is driven as follows.

That is, the oscillation output signal of the oscillation circuit 11 is transmitted to the modulation circuit 1.
AM modulated by 2, 13 and 14, detected by detection diodes 15, 16 and 1γ, and sent to drive circuit 8.
, 9 and 10.

The modulation circuits 12, 13 and 14 include sensors (shown as 20 in FIG. 1) located at 120 degrees from each other.
Therefore, the output signals of the modulation circuits 12, 13, and 14 have a three-phase relationship with each other.

Therefore, the output signals of the drive circuits 8, 9 and 10 are also 3
The stator coils 5, 6 and 7 are driven by three-phase signals.

The rotational speed of the rotor 2, ie, the rotational speed of the first turntable, is detected by the pickup coil 18.

The speed signal detected by the pickup coil 18 is applied to the oscillation circuit 11 via the amplifier circuit 19, and in order to control the output signal level of the oscillation circuit 11, the turntable 1 rotates at a constant rotation speed. do.

The speed control is performed such that when the turntable 1 rotates faster, the output signal level of the oscillation circuit 11 is decreased, and when the rotation of the turntable 1 becomes slower, the output signal level is increased.

In the above driving state, the detection diode 1
5.16 and 17 are forward biased.

Next, the electromagnetic brake device will be explained.

A speed signal from the pickup coil 18 is used as a signal for operating the electromagnetic brake.

The electromagnetic brake device includes the pickup coil 18, first and second amplification circuits 21 and 22, first and second
and third switching diodes 23, 24 and 25,
It consists of first, second, and third drive circuits 8, 9, and 10, first, second, and third stator coils 5, 6, and 7, a brake switch 26, and a bias circuit 27.

The pickup coil 18 is divided into two parts, each of which is arranged so that the phases are different from each other.

When the turntable 1 is in a steady rotation state, the pickup coil 18 is applied with a bias voltage of 2 through the resistor 28 of the bias circuit 27, and in the navel state, the first to third switching diodes are switched on. 23 to 25
A predetermined bias is applied to points P, Q, and R so as to have a reverse bias.

Therefore, in the steady rotation state, the electromagnetic brake device does not act on the stator coils 5, 6 and T at all, and the stator coils 5, 6 and I are connected to the detection diode 1.
Drive signals from 5, 16 and 17 are applied.

In order to stop the turntable 10 rotations, the brake switch 26 is pressed while the turntable 1 is in steady rotation.
When turned on, the transistor 29 of the bias circuit 27
becomes conductive, and the bias of the pickup coil 18 becomes ■1
to V2 (V t < V t.

Therefore, the first to third switching diodes 23 to 25 are forward biased, and the output signal of the pickup coil 18 is transmitted through the first and second amplifier circuits 21 and 22 and the first to third switching diodes 23 to 25. to points P, Q and R.

At that time, the detection diodes 15, 16 and 17 are reverse biased, so the drive signal is transmitted to the stator coils 5 to 7.
is no longer applied.

Therefore, the first to third stator coils 5 to T act on the rotor 2 as brakes and operate to stop the rotor 2 and turntable 1 quickly and smoothly.

The signal from the pickup coil 18 is sent to the sensor 20.
It is sufficient if the signal is in opposite phase to the signal detected from the drive signal (which becomes the drive signal).

Therefore, the pickup coil 18 is connected to the sensor 20 (3
60'Xn, 1 (n is an integer), and if their two output terminals are connected in the opposite way to the case of the sensor 20, a brake signal having the opposite phase to the drive signal can be obtained.

For example, if there are 3 sensors, you can install 3 pickup coils and make the corresponding ones have opposite phases.
, t, and the like, two pickup coils and three differentially connected drive circuits may be combined to obtain the above-mentioned reverse phase signal.

The first to third drive circuits 8 to 10 are differentially connected.

Therefore, by applying a predetermined bias to point Q, applying the first brake signal from the first amplifier circuit 21 to point P, and applying the second brake signal from the second amplifier circuit 22 to point R,
The output signals of the first to third drive circuits 8 to 10 are applied to the first to third stator coils 5 to 7 in a three-phase relationship to obtain the necessary braking force.

In the present invention, a brake signal is obtained by detecting the rotational speed of the rotor 2.

Therefore, if the rotational speed of the rotor 2 is high, the brake signal will be large, and if it is small, the brake signal will be small. As long as the rotation of the rotor 2 is stopped, the brake force is applied and the brake is released as soon as the rotation of the rotor 2 stops. Therefore, there is no problem such as reverse rotation, and the rotation can be stopped quickly and smoothly.

Note that the brake switch 26 can also be used as a rest switch for the pickup arm, and in such a case, the brake device according to the present invention can be automatically operated.

Further, in the embodiment, the same pickup coil is used to generate the drive signal and the brake signal, but a dedicated pickup coil for generating the brake signal may be provided separately, or other vehicle inventions may be used. Various circuit modifications are possible within the scope of the subject matter.

As described above, the present invention can provide a brake device with a novel configuration not seen in the past, and is particularly effective when used in a direct drive type record player.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG. 2 is a circuit diagram showing its detailed circuit. Explanation of main drawing numbers, 2... Rotor, 5, 6, 7... Stator coil, 8, 9. 10... Drive circuit, 18...
・Pickup coil.

Claims (1)

[Claims] 1. A motor that includes a rotor and a stator for driving the rotor, and that rotates the rotor by applying a drive signal to the stator, in which a signal corresponding to the rotational speed of the rotor is detected. a pickup coil provided opposite to the rotor; a signal switching circuit that is switched to apply either the drive signal or the output signal from the pickup coil to the drive circuit of the stator; and a signal switching circuit that applies a bias to the pickup coil. and a bias circuit for supplying a bias voltage of the first level, and the bias circuit is configured to be able to switch and generate a bias voltage of a first level and a second level bias voltage greater than the second level, and when stopping the rotation of the rotor. An electromagnetic brake characterized in that the output signal from the pickup coil is applied as a brake signal to the drive circuit by generating a second level bias voltage from the bias circuit and switching the signal switching circuit. Device. 2. The electromagnetic brake device according to claim 1, wherein the drive signal and the output signal from the pickup coil have a relationship of opposite phases to each other. 3. The electromagnetic brake device according to claim 1, wherein the pickup coil also serves as a pickup coil that generates a control signal for keeping the rotational speed of the rotor constant.