JPH03183385A - Spin motor brake circuit for disc player - Google Patents

Abstract

PURPOSE:To stop a spin motor reliably with no influence of external noise by detecting the rotational direction of a disc and applying brake voltage onto the spin motor in the reverse direction from the detected rotational direction. CONSTITUTION:Rotational direction and speed of a disc 8 being driven by a spin motor 1 are detected at a detecting section 4. A control section 7 being operated by a control command signal applies a voltage onto the spin motor 1 based on the rotational direction detection signal provided from the detecting section 4 thus braking the spin motor 1 in reverse direction from the disc 8. When the rotational speed detection signal from the detecting section 4 drops below a set value, voltage to be applied onto the spin motor 1 is brought to zero. Consequently, even when judgment of speed drop to a predetermined value is prevented by external noise, the spin motor 1 does not rotate in reverse direction but stop positively. By such arrangement, the disc 8 can be protected against damage.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a spin motor braking circuit for a disc player.

<Prior Art> Conventionally, as this type of spin motor braking circuit, the one shown in FIG. 5, for example, is known.

In this braking circuit, the spin motor braking section 37 that receives a braking command signal from the stop button 3 applies a voltage for reverse rotation to the spin motor l, while the eye pattern detecting section 34
detects the period of the eye pattern of the disk 8 that is rotationally driven by the spin motor 1, and when the detected eye pattern period becomes longer than a preset value, it is determined that the spin motor 1 has almost stopped. , the control unit 37 stops applying voltage to the spin motor l, and brakes the spin motor l.

<Problems to be Solved by the Invention> However, although the eye pattern detection unit 34 of the conventional spin motor braking circuit described above can determine whether the speed of the spin motor 1 has fallen below a certain low speed, it cannot determine the rotation direction of the spin motor I. cannot be detected. Therefore, when the spin motor slows down to below the certain low speed due to braking due to the application of a reverse voltage, if sustained noise happens to come in from the outside and it becomes impossible to determine whether the spin motor has stopped, the reverse voltage will continue to be applied and the spin motor will slow down. After stopping, it begins to rotate in reverse, and its rotational speed quickly exceeds the above-mentioned constant low speed. At this time, even if the continuous noise stops and the eye pattern detection unit 34 returns to normal operation, the eye pattern detection unit 34 cannot detect the reversal of the rotation direction, so it determines that the braking is still insufficient and starts the spin motor. If a reverse voltage is continued to be applied to the spin motor 1, the spin motor 1 cannot be stopped and continues to rotate at high speed in the reverse direction, resulting in defects such as damage to the disk 8.

Therefore, an object of the present invention is to detect not only the rotational speed but also the rotational direction of the disk and apply a braking voltage to the spin motor in the opposite direction to the detected rotational direction, thereby ensuring reliability without being affected by external noise. An object of the present invention is to provide a spin motor braking circuit for a disc player that can stop one spin motor and prevent damage to a disc.

<Means for Solving the Problems> In order to achieve the above object, a spin motor braking circuit for a disc player of the present invention includes a detection unit that detects the rotation direction and rotation speed of a disc rotationally driven by a spin motor of a disc player. When a brake command signal is received,
When a voltage is applied to the spin motor to rotate the spin motor in a direction opposite to the rotation direction of the disk based on the rotation direction detection signal from the detection section, the rotation speed detection signal from the detection section is The spin motor includes a control section that makes the voltage applied to the spin motor zero when the voltage becomes equal to or less than a predetermined set value.

Function> The detection unit detects the rotational direction and rotational speed of the disk rotationally driven by the spin motor, and outputs a rotational direction detection signal and a rotational speed signal. When the control unit receives the braking command signal, the control unit applies a voltage to the spin motor to rotate the spin motor in a direction opposite to the rotation direction of the disk based on the rotation direction detection signal from the detection unit, and also detects the rotation direction. When the rotational speed detection signal from the spin motor becomes equal to or less than a preset value, the applied voltage to the spin motor is made zero. In this way, unless the normal judgment operation is hindered by external noise etc., the control section always causes the spin motor to move in the opposite direction to the driving direction when the rotation speed of the spin motor exceeds the set speed in response to the braking command signal. Since a voltage is applied in the braking direction, even if the normal judgment operation of the control unit is disturbed by external noise etc. near the above set speed, the braking action will always be performed in the normal judgment operation range, and the spin motor will be reliably controlled. can be stopped.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

1 and 3 are a block diagram and a configuration diagram showing an embodiment of a spin motor braking circuit for a disc player according to the present invention. This braking circuit consists of a detection disk 2 fixed perpendicularly and coaxially to a drive shaft 11 of a spin motor 1, and a pair of photo-ink brakes 12 provided opposite to this detection disk 2. . a rotational direction determination section 5 that determines the rotational direction of the disk based on the rotational direction detection signal from the rotational direction detection signal from the rotational direction detection signal from the rotational direction determination section 4;
and a rotational speed determination section 6 that determines whether the rotational speed detection signal from the detection section 4 has become equal to or less than a preset value, and a rotational speed determination section 6 that determines whether or not the rotational speed detection signal from the detection section 4 has become equal to or less than a predetermined setting value. Spin motor control that applies a voltage that rotates the motor 1 in the opposite direction to the rotation direction to the spin motor I, and also reduces the voltage applied to the spin motor 1 to zero when the rotation speed detection signal becomes equal to or less than the above set value. It consists of section 7.

A control section is composed of the rotation direction determining section 5, the rotation speed determining section 6, and the spin motor control section 7, and the same blocks as in the conventional example shown in FIG. 5 are given the same numbers.

As shown in FIG. 2, the detection disk 2 has the same number of fan-shaped white and black patterns alternately provided in the circumferential direction on the center portion and the outer circumferential portion, which are divided into inner and outer portions by a circle 21. The black and white patterns are arranged offset from each other on the outer periphery. On the other hand, the photointerrupter 12. converts this black and white pattern into an electrical signal.
13 is provided on the upper surface of a bracket 16 fixed to the chassis 14 shown in FIG.
Take a position as shown in FIG. 2 with respect to the detection disk 2.

FIG.
2.13 shows the electrical signal output from During disc playback, when the spin motor 1 rotates forward and the detection disc 2 rotates in the direction shown by arrow A in FIG. The output of the interrupter 12 changes from L, which represents black, to H, which represents white, and then the output of the inner photo ink converter 13 similarly changes from L to I-1+. Moreover, when the spin motor 1 reverses in the direction opposite to arrow A, the upper part of FIG.

The lower waveforms will be swapped.

The rotation direction determining section 5 includes a photo interrupter 12.1.
When the output signal of the latter rises from I7 to ■1, if the output signal of the former is H, it is determined that the disk is rotating in the normal direction (as indicated by the broken line in Figure 4). reference)
, H signals are output to the spin motor control unit 7, while if the former output signal is L at the above-mentioned time point, it is determined that the disk is rotating in reverse, and an L signal is output to the spin motor control unit 7.

Then, the spin motor control unit 7 outputs a voltage to the spin motor 1 to cause the spin motor 1 to rotate in reverse and forward rotation, respectively, in accordance with the signal HIL.

On the other hand, the rotation speed determination section 6
Upon receiving the output signal from 2, the number of pulses of this output signal per unit time is counted, and whether or not this count value is less than a preset value corresponding to the rotation speed before the spin motor stopped. is determined, and when the value is below, a stop signal is output to the spin motor control unit 7, the voltage applied to the spin motor I is made zero, and the spin motor I is stopped.

The spin motor braking circuit configured as described above operates as follows.

Now, when the disk 8 fitted on the tip of the drive shaft +1 is being driven in normal rotation by the spin motor l and the image signal recorded on the disk 8 is being reproduced, a braking command signal is output from the stop button 3. Suppose that Then, the detection unit 4
In response to the braking command signal, the photointerrupter 12
．． 13 is operated, and the black and white pattern of the detection disk 2 rotating together with the drive shaft 11 is detected as an electric signal as shown in FIG. 4 and output to both determining sections 5.6. The rotation direction determination unit 5 determines whether the spin motor l rotates in the normal direction or
It determines reverse rotation and outputs H and L signals to the spin motor control unit 7 depending on whether it is forward or reverse, and upon receiving this, the spin motor control unit 7 starts the spin motor 1 according to the H or L signals. A voltage is applied to the spin motor I to cause reverse or forward rotation, that is, a voltage to brake the spin motor. by this,
The rotational speed of the spin motor 1 is gradually reduced.

On the other hand, the rotation speed control unit 6 counts the number of pulses of the electric signal per unit time, determines whether this count value has become equal to or less than a set value corresponding to the rotation speed immediately before stop +L, and When the following occurs, the spin motor control unit 7
A stop signal is output to make the voltage applied to the spin motor 1 by the spin motor control section 7 zero. As a result, the power supply to the spin motor l immediately before stopping is cut off,
The spin motor l is completely stopped by the frictional force.

In this way, as long as the determination operations of both determination units 5.6 are not hindered by external noise etc., the spin motor control unit 7 receives the H and L signals and stop signals from both determination units 5 and 6, and
If the rotational speed of the spin motor l exceeds the set speed,
Since a voltage is always applied to the spin motor l in the braking direction opposite to the driving direction, even if the judgment operation is temporarily disturbed by external noise near the above set speed, it will always work in the normal judgment operation range other than that. A braking action can be exerted, and the spin motor 1 can be reliably stopped. In other words, as in the conventional example described in FIG. 5, since the rotation direction of the spin motor I cannot be detected, an abnormal determination operation caused by external noise may cause the spin motor I to rotate at high speed in the opposite direction, causing damage to the disk 8. I never do.

It goes without saying that the present invention is not limited to the illustrated embodiment.

<Effects of the Invention> As is clear from the above description, the spin motor braking circuit for a disc player of the present invention detects the rotational direction and rotational speed of the disc driven by the spin motor using the detection unit, and outputs a braking command signal. The control unit that receives and operates applies a voltage to the spin motor based on the rotation direction detection signal from the detection unit to brake the spin motor in a direction opposite to the rotation direction of the disk, and to control the rotation from the detection unit. Since the voltage applied to the spin motor is set to zero when the speed detection signal falls below a predetermined set value, it is difficult to determine whether the predetermined low rotational speed has been reached temporarily due to external noise, etc. Even if the spin motor is prevented from rotating at high speed in the opposite direction, the spin motor can be reliably stopped, and damage to the disk due to runaway of the spin motor can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a spin motor braking circuit for a disc player according to the present invention, FIG. 2 is a plan view of the detection disc of the above embodiment, and FIG. 3 is a configuration diagram of the above embodiment.
FIG. 4 is a diagram showing the output signal from the detection section of the above embodiment,
FIG. 5 is a block diagram of a conventional spin motor braking circuit. l... spin motor, 2... detection disc, 3...
Stop button, 4...detection unit, 5...rotation direction determination unit,
6... Rotation speed determination unit, 7... Spin motor control unit, 8... Disk, 12.13... Photo ink club. Patent applicant: Sharp Corporation Agent
Patent attorney Aoi Ao and one other person Figure 3 Figure 4 Time Figure 5

Claims (1)

[Claims] (1) A detection unit that detects the rotational direction and rotational speed of a disc rotationally driven by a spin motor of a disc player, and when receiving a braking command signal, the spin motor detects the rotation direction detection signal from the detection unit. Applying a voltage to the spin motor to rotate the disc in a direction opposite to the rotational direction of the disk, and when the rotational speed detection signal from the detection section becomes equal to or less than a predetermined set value,
A spin motor braking circuit for a disc player, comprising a control unit that reduces the voltage applied to the spin motor to zero.