JPS5857830B2 - Turntable drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turntable drive circuit for a record player.

In a high-end record player, the motor that drives the turntable starts rotating, quickly reaches a predetermined number of revolutions, quickly reaches the changed number of revolutions after changing the number of revolutions, and quickly reaches the set number of revolutions when it stops. Something like stopping is required.

The rise time after the motor starts rotating or when the rotation speed switching wave reaches a predetermined rotation speed is determined by the torque of the motor and the inertia weight σ of the turntable attached to the motor.

Further, in conventional record players, the fall time for the motor to reach a stopped state or a switched rotation speed from a predetermined rotation speed is determined by a negative torque determined by mechanical friction loss, and is a long time.

Therefore, in conventional record players that use an AC motor as the motor for driving the turntable, when the rotation is stopped or when the rotation speed is changed, a DC current is applied to the main winding or the sub winding of the AC motor. The conventional method was to cause a fixed loss or a fluid loss in the motor by causing a current to flow, thereby reducing the fall time.

In addition, in the case of a DC motor, the direction of rotation varies depending on the polarity of the supplied voltage, so when you want to stop or reduce the rotation of the motor, apply a voltage in the opposite direction to the motor. By generating directional torque, the fall time of the DC motor's rotation is made faster.

In the case of this DC motor, if a reverse voltage is applied even after the motor has completely stopped or the rotational speed has decreased to a predetermined rotational speed, the motor, that is, the turntable, will rotate in the reverse direction or become lower than the predetermined rotational speed, which is undesirable.

Therefore, in order to quickly stop such a DC motor or reduce the rotation speed to a predetermined speed, and to prevent the motor from rotating in the opposite direction or lowering the rotation speed below a predetermined speed, it is necessary to detect the rotation direction of the motor, that is, the turntable, It is necessary to control the rotation of the motor based on the detected output.

In view of the above points, the present invention uses a simple enclosure structure to quickly and reliably change the rotation speed of the turntable to another predetermined rotation speed when the turntable is switched from a certain predetermined rotation speed to another predetermined rotation speed lower than this. The purpose of this paper is to propose a turntable drive circuit that can reach a rotational speed of .

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a turntable drive circuit according to the present invention.

Reference numerals 1 and 1B are frequency signal generating means that generate frequency signals having a phase difference in polarity depending on the direction of rotation of the turntable R, respectively.

Here, the turntable R is directly connected to the motor 24.

A pair of frequency signal generating means 1 and 1B are formed on the circumferential surface of the turntable R in this example, and are alternately N and S.

A magnetized part m magnetized as N, S......, and a pair of magnetized parts arranged along the circumferential direction of the magnetized part m at a predetermined interval on this magnetized part m. It consists of magnetic heads Ha and Hb.

Reference numeral 2 denotes a phase difference polarity discrimination circuit, which is composed of a pair of limiters 3.4, a differentiation circuit 5, and a sample and hold circuit 6.

Frequency signals output from the magnetic heads Ha and Hb are supplied to limiters 3 and 4, respectively.

Further, the output of the limiter 3 is directly supplied to the sample and hold circuit 6, and the output of the limiter 4 is supplied to the differentiating circuit 5.
The output of the differentiating circuit 5 is supplied to a sample and hold circuit 6.

Then, the rotation direction detection output of the turntable R can be obtained on the output side of the phase difference polarity discrimination circuit 2, that is, on the output side of the sample and hold circuit 6.

FIG. 2 shows the arrangement relationship between the magnetized surface m and the magnetic heads Ha and Hb.

N t S t in the circumferential direction at equal intervals on the magnetized surface m
It is magnetized so that magnetic poles are formed alternately as N t S . . . .

The pitch from one magnetic pole to the next magnetic pole of the same polarity on this magnetized surface m is λ.

And on the magnetized surface m, this pitch λ.

(7) In other words, magnetic poles are formed alternately in the order of N, S, N, S, etc. every 2.2 cm.

The magnetic heads Ha and Hb are of the velocity responsive type in this example.

The magnetic heads Ha, Hb may be magnetic flux responsive magnetic heads.

Further, these magnetic heads Ha and Hb are arranged at a predetermined pitch λ in the direction of rotation of the magnetized surface m, and are opposed to each other.

In this example, this pitch λ is selected to be 4, for example.

The clockwise rotation of the turntable R is defined as a forward direction n, and the opposite direction is defined as a reverse direction r.

In this way, the output signals ea and eb of the magnetic heads Ha and Hb become outputs as shown in the formula below, respectively.

ea=K Bm p cos p t = K Bm p 5in(pt +7) ”” (
1) λ eb = K Bm p cos (pt ± 2r; r ) λ = K Bm p sin (pt-In ± 2π, )
-(2) However, here, K is a constant, Bm is the peak λ value of the magnetic flux density, and p is the angular frequency.

Also, let `` be α. Thus, when the turntable R is rotating in the positive direction n, the frequency signals obtained from the magnetic heads Ha and Hb, ea and eb are the magnetized surfaces m in FIG. 3A. On the other hand, it becomes a sine wave as shown in FIGS. 3B and 3C.

Therefore, by supplying the frequency signals shown in FIG. 3B and C to the limiters 3 and 4, rectangular wave signals as shown in FIG. 3 and E are obtained, respectively.

In this case, it can be seen that the frequency signal obtained by the magnetic head Hb is delayed in phase by α from the frequency signal obtained by the magnetic head Ha.

FIG. 3F shows the differential output of the differential circuit 5.

In this way, each output from the limiter 3 and the differentiating circuit 5 is supplied to the sample and hold circuit 6, so that the output of the limiter 3 shown in Fig. 3 is sampled and held with the differential output shown in Fig. 3F. At the output side of the hold circuit 6, a signal of level "1" as shown in FIG. 3G is obtained.

The signal shown in FIG. 3DtE also indicates its level with "O" and "1".

When the turntable R is rotating in the opposite direction r,
The output waveforms of each part are as shown in FIGS. 4A to 4G, corresponding to FIGS. 3A to 3G.

In this case, the frequency signal of magnetic head Hb is
This means that the phase is advanced by α compared to the frequency signal from a.

In this case, in the sample and hold circuit 6, the output of the limiter 3 is sampled and held by the differential output of the differentiator 5, so that the sample and hold output is at the level "O" as shown in FIG. 4G. It becomes a signal.

That is, when the level of the output signal of the sample and hold circuit 6 is "1", it indicates that the turntable R is rotating in the positive direction n, and when it is rOJ, it is rotating in the reverse direction r.

Similarly, in this embodiment, a pair of magnetic heads Ha and I
(The interval λ between b is between 0 and λ), so when the turntable R is rotating in the positive direction n as shown in FIG. 5A, the output of the sample and hold circuit 6 is "1", When rotating by λ in the opposite direction r, it becomes "O".

Directly, this λ is 7 and λ.

5, the output of the sample and hold circuit 6 is inverted as shown in FIG. 5B.

Next, other parts of the record player will be explained with reference to FIG.

A servo is applied to the motor 24 so that it rotates at 45rlln or 33Hrp''.

18 is a frequency-voltage conversion circuit, which includes a rotating body, that is,
A frequency signal corresponding to the rotation of the motor 24 or the turntable R is supplied, and in this example, a rectangular wave signal from the limiter 3 is supplied.

The angular frequency ω and voltage V of this frequency-voltage conversion circuit 18
As shown in FIG. 6, when α=0, the relationship with V=Vm(
45rpln and 33Trpffi.
and show different characteristic curves.

This frequency-voltage conversion circuit 18 is configured by, for example, a differential circuit, a charging/discharging circuit, and an integrating circuit that are connected in series.

This charging/discharging circuit has a rotation speed of 4 for the turn tape/I and 'R.
5 rpm, 33. A series circuit of a resistor and a capacitor with different resistance values that are switched according to rpHl is connected to a power supply, and a switching transistor is connected in parallel to the capacitor. When the transistor is turned on by a pulse, the charge in the capacitor is discharged, and the capacitor is charged with a time constant determined by the constants of the resistor and capacitor that were switched when the transistor was turned off. The voltage across the capacitor gradually increases until the transistor turns on.

The output V of this frequency-voltage conversion circuit 1B is the comparator circuit 19
, and is compared with the reference voltage VO from the reference voltage source 22 . After the comparison output V-Vo is amplified by the servo amplifier 20 , it is sent to the motor 24 through the drive signal switch 21 to drive the motor 24 in normal rotation. It is designed to be supplied as a signal.

In this case, the reference voltage Vo of the reference voltage source 22 is common to the rotation speeds of the turntable R of 45 rpm and 334 rpm, and as shown in FIG. 6, the output voltage V of the frequency-voltage conversion circuit 18 becomes equal to the reference voltage VO. When the turntable R or the motor 24 is 45rl)m and 33-r
It is designed to rotate at a rotational speed of pm.

Reference numeral 7 denotes a drive signal switching control circuit that switches and controls the forward rotation and reverse rotation drive signals supplied to the motor 24, and will be described below.

In this drive signal switching control circuit 7, 8-12 are its input/output terminals.

The input terminal 8 is grounded through a start/stop control switch 13.

This switch 13 is a switch that is turned on temporarily, and is the same for both starting and stopping.

The output side of the frequency-voltage conversion circuit 18 is connected to the input terminal 9.

The output terminal of the sample and hold circuit 6 is connected to the input terminal 104.

Output terminals 11 and 12 are connected to the input terminal of drive signal switch 21.

The drive signal switching control circuit 7 includes a T-type flip-flop circuit 14, a NAND circuit 15, an inverter 6, and an AND circuit 17.

The input terminal 8 is connected to the T input terminal G of the T-type flip-flop circuit 14, and the output terminal obtained from the output Q is connected to one input terminal of the NAND circuit 15.

Input terminal 9 is connected to the other input terminal of NAND circuit 15 .

The output terminal of the NAND circuit 15 is connected to one input terminal of the AND circuit 1γ, and the input terminal 10 is connected to the other input terminal of the AND circuit 17.

The output terminal of the AND circuit 17 is connected to the output terminal 12.

The output terminal of the NAND circuit 15 is connected to the output terminal 11 through the inverter 6.

Further, 23 is a voltage source from which a constant voltage can be obtained, and is connected to the drive signal switch 21.

Next, the driving signal switching control circuit 7 and the rotational state of the motor 24 controlled thereby will be explained.

The output of the flip-flop circuit 14 is 01, the output of the sample hold circuit 6, that is, the input of the input terminal 10, is Q2, the output of the frequency-voltage conversion circuit 18, that is, the input signal Q3 of the input terminal 9, and the output of the output terminal 11 is Q4. and output terminal 12
The output of is set to 05, and the truth table at this time is shown in FIG.

Then, the state is labeled as a to.

Also, these Q. The output of is either "0" or "1".

State a indicates a state in which the power switch is off. b shows a state in which the motor 24 is stopped or the turntable R is forcibly rotated by hand or the like in the opposite direction r within the range of the characteristic curve shown in FIG.

In state C, turntable R is 45 rlm or 33
' The state in which a stop signal is obtained from the flip-flop circuit 14 is shown after the normal rotation in the positive direction m at rpm is forcibly rotated to a higher rotational speed by hand or the like.

In state d, turntable R is 451 pIll or 33
, rpm, and then a stop signal is obtained from the flip-flop circuit 14.

In state e, turntable R is equal to 61 and 45 rpm.
, indicates a state in which it is forcibly rotated in the opposite direction r at a high speed of 33-L rpm or higher.

State f indicates the state at the moment when the start signal is obtained from the flip-flop circuit 14.

In condition g, the turntable R is from 45 rlm to 33-rp.
The state when the rotation speed changes is shown in m.

The state indicates that the turntable R is at the beginning of rotation or is rotating steadily.

When Q1=1, the turntable R starts rotating, when Q1=O, the turntable R stops, and when Q2-1, the turntable R rotates normally in the forward direction n. and when Q2=O, turntable R
is stopped or rotating in the opposite direction r, when Q3-1 is the time when the output of the frequency-voltage conversion circuit 18 is not zero, and when Q3=0, the output of the frequency-voltage conversion circuit 18 is 18 is when it is zero.

Moreover, the logical formula for Q4 is expressed as the following formula.

Q4=QIQ3 The logical expression for the output Q5 is expressed as follows.

Q5=QIQ3Q2 Motor 24 to 45rlm or 33-! -rpm+ When the iron is to be rotated, by temporarily turning on the switch 13, the amplified maximum comparison voltage vm-Vo from the comparator circuit 19 is applied to the motor 24.
Rotation starts rapidly.

As the rotation speed, that is, the angular frequency ω increases, the output voltage of the frequency-voltage conversion circuit 18 decreases, and the voltage becomes Vo, that is, the comparison output voltage of the comparison circuit 19 becomes zero (
In this case, the motor 24, that is, the turn table R is 45r.
Rotating at lm or 33-Hrpm.

To stop the rotation of the motor 24, that is, the turntable R, turn on the switch 13 temporarily.
The motor 24 is not supplied with electric power from the servo amplifier 20, but a constant voltage that causes the motor 24 to rotate in the opposite direction, that is, a reverse drive signal, is supplied from the voltage source 23 to the drive signal switch 2.
1 to the motor 24 (thereby, the motor 24 is braked).

Then, the rotational direction of the motor 24, that is, the turntable R, is detected by the phase difference polarity discrimination circuit 2, and at the moment when the motor 24 is about to turn from the forward direction n to the reverse direction r, that is, the motor 24 or the turntable R is detected. The moment when the motor 24 stops is detected, the energization to the motor 24 is canceled, and the motor 24
In other words, the turntable R remains in a stopped state.

When the motor 24, that is, the turntable R, is rotating at 45 rpm, and the rotation speed is reduced to 33-HrpIn, the output voltage of the frequency-voltage conversion circuit 18 immediately becomes zero, and the motor 24 has a servo increaser. While the voltage from the width switch 20 is not supplied, a constant voltage with a polarity that causes the motor 24 to rotate in the opposite direction is applied from the voltage source 23 via the drive signal switch 21, a brake is applied to the motor 24, and its rotational speed is changed. decreased to 33-! -rpm is reached and the output voltage VO is obtained from the frequency-voltage conversion circuit 18, the servo voltage from the servo increase amount 20 is applied so as to rotate the motor 24 in the forward direction n at 33Trpl.

Father, the rotation speed of motor 24, that is, turntable R, is 33.
-! -rpm to 45rl)l, the output voltage V of the frequency-voltage conversion circuit 18 rises rapidly, and based on this, the supply voltage to the motor 24 increases dramatically, and the rotational speed immediately increases. 45rpi, and from then on, maintain that number of rotations.

According to the turntable drive circuit described above, the motor 24, that is, the turntable R, can be instantly raised to normal rotation with a simple configuration, and can be instantly brought to a stopped state.
Furthermore, the rotation speed changeover, that is, the reciprocal changeover between predetermined high and low rotational speeds, is carried out reliably and quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a turntable driving circuit according to the present invention, and FIG. 2 shows a magnetized surface m and a magnetic head H.
FIGS. 3 and 4 are waveform diagrams showing the waveforms of the output signals of each part of the phase difference polarity discrimination circuit 2 in FIG. 1, and FIG. A waveform diagram showing the output waveform of the sample and hold circuit 6, FIG. 6 is a curve diagram showing the frequency-voltage conversion characteristics of the frequency-voltage conversion circuit 18 of FIG. 1, and FIG. 7 shows signals of various parts of the drive signal switching control circuit. Show the truth table of R and 24 are turntables and motors as rotating bodies, and 2 is a phase difference polarity discrimination circuit.

Claims (1)

[Claims] 1. A motor that drives a turntable, a pair of frequency signal generating means that generates a pair of frequency signals each having a phase difference in polarity depending on the direction of rotation of the turntable as the turntable rotates; a phase difference polarity determining circuit which supplies a pair of frequency signals from the frequency signal generating means and determines the polarity of the phase difference to detect the rotating direction of the turntable; A detection circuit for detecting a rotational state as to whether the rotational speed of the turntable is equal to or higher than a predetermined rotational speed, a rotational direction detection output from the phase difference polarity discrimination circuit, and a rotational state detection output from the detection circuit are supplied. , a drive signal switching control means for switching and controlling a forward rotation and a reverse rotation drive signal supplied to the motor, and applies the reverse rotation drive signal to the motor when the rotation speed of the turntable is equal to or higher than the predetermined rotation speed. and (4) a turntable drive circuit, characterized in that the supply of the reverse rotation drive signal to the motor is cut off when the rotational speed of the turntable matches the predetermined rotational speed.