JPH0950668A - Detection circuit for suspended rotation of turntable of disk player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the suspended rotation of the turntable loaded with a disk by detecting a change in pulse signals corresponding to the signals obtained by a magnetic sensor which detects the rotation of the turntable. SOLUTION: When the suspension switch 10 of the control switch is operated in a disk player working in a playback mode, a system control circuit 9 actuates suspension control by a servo signal processing circuit 5 and, at the same time, a brake signal is outputted from a motor control circuit 11 for a specified period to cause reverse rotation of the motor 2. As the result, the motor 2 gradually rotates and finally stops the rotation of the turntable. At this time, the intervals of the pulse signals which are outputted to the output terminal of a signal generating circuit 13A are elongated with the decrease of the rotational speed of the table 1. When the table 1 stops, the output level of the signal at the terminal 13A varies no longer. Through this, the circuit 9 recognizes the suspension of the table 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc player configured to read a signal recorded on a disc by an optical pickup, and more particularly to a rotation stop detection circuit of a turntable.

[0002]

2. Description of the Related Art A disk player which performs a reproducing operation by reading out a signal from a disk on which information data such as music is recorded by a digital signal using an optical pickup has become widespread. One of them is a CD player.

Since the signal reading operation in such a CD player is performed by rotationally driving and controlling the disk at a constant linear velocity, it is possible to read the signal recorded on the inner peripheral side of the disk. The rotation speed of the disc greatly differs from that when the signal recorded on the outer circumference side is read. Further, in such a CD player, the disc does not stop rotating immediately when the switching operation from the reproducing operation state to the stopped state is performed, so that the disc rotates in the opposite direction to the electric motor that rotates the disc during the stopping operation. It is configured to supply a brake signal that causes the brake signal.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The rotation speeds of the inner and outer circumferences of the disc are very different.Therefore, if the supply time of the brake signal supplied to the electric motor during the stop operation is the same, the rotation of the disc may not stop due to insufficient brake or the brake may be excessive. Therefore, there is a problem that the disk is rotated in the opposite direction.

As a method for solving such a problem, the position of the optical pickup is detected by using the time information recorded on the disc, and the supply time of the brake signal is changed according to the position of the optical pickup. There is a way to
When the disc has an abnormality such as a scratch or an eccentricity, there is a problem that the disc cannot be stopped as designed.

A portable type CD player is generally provided with a disc opening / closing lid for covering a storage portion for storing a disc, and the disc is turntable by rotationally displacing the disc opening / closing lid to the open position. It is configured to be taken out from above. In the CD player configured as described above, the operation of displacing the disc opening / closing lid after the stop operation is generally performed. However, in this case, when the disc does not stop rotating, the disc moves to the outside. There is a problem that the disk will be ejected and the disk will be damaged.

The present invention seeks to provide a turntable rotation stop detection circuit used to solve such problems.

[0008]

A turntable rotation stop detection circuit according to the present invention is provided to detect the rotation of a turntable which is rotationally driven by an electric motor and on which a disk is placed, and the rotation of the turntable. It comprises a signal generating circuit for generating a pulse signal corresponding to the signal obtained from the rotation detecting means.

[0009]

According to the present invention, there is provided a signal generating circuit for generating a pulse signal corresponding to the signal obtained from the rotation detecting means provided for detecting the rotation of the turntable on which the disk is mounted, and the signal generating circuit. The stop of the rotation of the turntable is detected by detecting the change in the pulse signal obtained.

[0010]

1 is a block circuit diagram showing an embodiment of a turntable rotation stop detection circuit of the present invention, and FIG. 2 is a plan view showing the state of magnetic poles of magnets provided on the turntable of the present invention. 3 is a signal waveform diagram for explaining the operation of the present invention.

In FIG. 1, reference numeral 1 denotes a turntable on which a disk D is placed and which rotates the disk D.
Reference numeral 2 is an electric motor for rotating the turntable 1.
Reference numeral 3 denotes an optical pickup having a photodetector for projecting a light beam onto a CD type disc D and receiving the light beam reflected by the signal surface of the disc D. Reference numeral 4 denotes an optical pickup of the optical pickup 3. An RF amplifier circuit 5 that amplifies the received RF signal and shapes the waveform of the RF signal, and a focusing control 5 that focuses the light beam of the optical pickup 3 on the signal surface of the disk D based on the signal obtained through the RF amplifier circuit 4. And a servo signal processing circuit 6 for performing tracking control for causing the light beam to follow the signal track on the signal surface and for controlling the feeding operation and track jump of the entire optical pickup 3, 6 is output from the RF amplification circuit 4. Digital signal processing circuit for performing digital signal processing of various output signals and demodulating various signals. D / A converter for converting the signal to an analog signal with a digital signal which is digitally processed by the barrel signal processing circuit 6 is input, 8 the D / A
It is an amplifier circuit that inputs the audio signals of the left and right channels converted into analog signals by the converter 7 and amplifies the signals.

Reference numeral 9 denotes a system control circuit to which the signal demodulated by the digital signal processing circuit 6 is input and which controls various operations according to the switching operation of each switch provided in the operation switch 10. Reference numeral 11 is an electric motor control circuit whose operation is controlled by the system control circuit 9 and has a function of controlling the rotating operation of the electric motor 2.

Reference numeral 12 denotes a magnetic sensor arranged at a position facing the back surface 1A of the turntable 1 of the electric motor 2, and detects a change in magnetic field obtained from a magnet provided on the back surface 1A of the turntable 1. It is configured to detect and output a signal according to the change. Magnetic poles are formed on the back surface 1A of the turntable 1 as shown in FIG. Reference numeral 13 is a signal generation circuit to which a signal obtained from the magnetic sensor 12 is input, and is configured to output a pulse signal as shown in FIG. 3 to the output terminal 13A.

Numeral 14 is a lock release circuit for bringing the lock mechanism for locking and holding the disc opening / closing lid, which covers the storage portion in which the disc D is stored, in the closed position into the unlockable state. The rotation of the turntable 1 is stopped. When it is detected, the lock mechanism operates to bring the lock mechanism into an unlockable state. Reference numeral 15 is a display circuit that is in an operating state when the rotation stop of the turntable 1 is detected, and is configured to drive the light emitting diode 16 to light.

In such a configuration, when the rotation speed of the turntable 1 becomes slower due to the stop operation, the pulse interval of the pulse signal output to the output terminal 13A of the signal generating circuit 13 becomes longer, and the turntable 1 rotates. When is stopped, the pulse signal is not output. Then, the system control circuit 9 outputs the output terminal 1 of the signal generating circuit 13.
When the pulse signal is no longer output from 3A, it is determined that the turntable 1 has stopped rotating, and a signal for putting the lock release circuit 14 and the display circuit 15 into an operating state is output.

The disc player according to the present invention is constructed as described above, and its operation will be described below. When the user operates a reproduction switch (not shown) in the operation switch 10, the system control circuit 9 performs a control operation to start the reproduction operation of the disc player. When such an operation is started, the optical pickup 3
Is in a state where the focusing control and the tracking control operation by the servo signal processing circuit 5 are performed and the reading operation of the signal recorded on the disk D rotationally driven by the electric motor 2 is performed.

The signal read by the optical pickup 3 is amplified by the RF amplifier circuit 4 and waveform-shaped and applied to the digital signal processing circuit 6 as a digital signal. The digital signal processing circuit 6 is
The digital signal output from the RF amplifier circuit 4 is demodulated, and various data signals included in the digital signal are extracted.

When information data (audio data) is extracted by signal processing by the digital signal processing circuit 6, the information data is subjected to error correction processing operation,
It is applied to the D / A converter 7. The digital signal applied to the D / A converter 7 is converted into an analog signal and then separated into stereo left and right channel signals and input to the amplifier circuit 8. Therefore, a signal such as music recorded on the disc D can be reproduced and heard.

The reproduction operation in this embodiment is performed as described above. Next, the operation when the stop operation is performed in the reproduction operation state will be described. When the stop switch (not shown) in the operation switch 10 is operated while the disc player is in the reproduction operation state, the system control circuit 9 performs the control operation for the stop by the servo signal processing circuit 5. With motor control circuit 11
A brake signal that causes the electric motor 2 to rotate in the opposite direction is output for a predetermined time. As a result, the rotation speed of the electric motor 2 gradually decreases and the rotation of the turntable 1 stops. However, as the rotation speed of the turntable 1 decreases, the pulse signal output to the output terminal 13A of the signal generation circuit 13 is reduced. The interval becomes longer as shown in FIG. When the rotation of the turntable 1 is stopped, the level of the signal output to the output terminal 13A does not change. Therefore, the system control circuit 9 can recognize that the electric motor 2, that is, the turntable 1 has stopped rotating.

When the system control circuit 9 detects the rotation stop of the turntable 1, it outputs a control signal to the unlock circuit 14 and the display circuit 15. As a result, the unlocking circuit 14 is put into operation, and the lock mechanism of the disk opening / closing lid is unlocked. Therefore, when the user performs an operation of rotating the disc open / close lid to the open position, the lock of the disc open / close lid is released and the disc open / close lid is displaced to the open position. Therefore, the operation of taking out the disk D from the turntable 1 can be performed. When the display circuit 15 is activated, the light emitting diode 16 connected to the display circuit 15 as a load is driven to light. Therefore, the user can recognize that the turntable 1 has stopped rotating due to the light emission of the light emitting diode 16, and can easily know that there is no problem even if the opening operation of the disc opening / closing lid is performed. .

In this embodiment, the magnetic sensor 12 is provided outside the electric motor 2 and the back surface 1A of the turntable 1 is provided.
Although the magnet is provided in the electric motor 2, the magnetic sensor may be provided inside the electric motor 2 to detect the change in the magnetic field obtained from the driving magnet provided inside the electric motor 2. Further, although the magnet is provided on the back surface 1A of the turntable 1, by providing the reflecting surface on the back surface 1A and providing the photosensor for irradiating the reflecting surface with light and detecting the change of the reflected light, the turntable 1 It can also be configured to detect a rotation stop.

Further, in the present embodiment, the fact that the turntable 1 has stopped rotating is displayed by the light emitting operation of the light emitting diode 16, but in order to display the number of songs recorded on the disc and the reproduction time. The liquid crystal display device provided may be used for displaying. Further, when the liquid crystal display is used, the rotation stop can be displayed by characters, and in this case, the user can easily recognize that the turntable has stopped rotating.

[0023]

The present invention is provided with a signal generating circuit for generating a pulse signal corresponding to the signal obtained from the rotation detecting means provided for detecting the rotation of the turntable on which the disk is mounted. The rotation stop of the turntable is detected by detecting a change in the pulse signal obtained from the generating circuit. Therefore, according to the present invention, since the rotation stop of the turntable is not affected by scratches on the disc as in the case of detecting the signal obtained from the disc, the rotation stop of the turntable is reliably detected. You can do it.

According to the present invention, a magnetic sensor or a photo sensor is used as the rotation detecting means of the turntable, and the rotation detecting means is provided outside the electric motor for rotationally driving the turntable. Therefore, the assembling work and the adjusting operation are facilitated. You can do it. Further, the present invention has an advantage that a cost increase can be suppressed by providing a magnetic sensor inside the electric motor and using a magnet for rotationally driving the electric motor.

Further, according to the present invention, when the stop of the rotation of the turntable is detected, the unlocking operation of the disk opening / closing lid covering the disk storage portion is made possible, so that the disk opening / closing lid is unlocked during the rotation of the disk. It is possible to reliably prevent the disc opening / closing lid from being opened. Since the present invention is configured to display that the turntable has stopped rotating, the user can easily recognize the timing of the opening operation of the disc opening / closing lid. Further, the present invention is configured to display that the turntable has stopped rotating by the characters displayed on the liquid crystal, so that the user can more reliably recognize the stop of rotation of the turntable.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a turntable rotation stop detection circuit of the present invention.

FIG. 2 is a plan view showing a state of magnetic poles of a magnet provided on the turntable of the present invention.

FIG. 3 is a signal waveform diagram for explaining the operation of the present invention.

[Explanation of symbols]

 1 Turntable 2 Electric Motor 3 Optical Pickup 5 Servo Signal Processing Circuit 6 Digital Signal Processing Circuit 9 System Control Circuit 11 Electric Motor Control Circuit 12 Magnetic Sensor 13 Signal Generation Circuit 14 Lock Release Circuit 15 Display Circuit 16 Light Emitting Diode D Disk

Claims (9)

[Claims] 1. A disc player configured to read a signal recorded on a disc by an optical pickup, wherein a turntable which is rotationally driven by an electric motor and on which the disc is placed, and a rotation of the turntable. The rotation of the turntable comprises a signal generating circuit for generating a pulse signal corresponding to the signal obtained from the rotation detecting means provided for detection, and detecting the change of the pulse signal obtained from the signal generating circuit. A turntable rotation stop detection circuit for a disc player, which is characterized by detecting stoppage. 2. The turntable rotation stop detecting circuit according to claim 1, wherein a magnetic sensor is used as the rotation detecting means. 3. The turntable rotation stop detection circuit according to claim 2, wherein a magnetic sensor is provided inside the electric motor. 4. The turntable rotation stop detection circuit according to claim 1, wherein a photosensor is used as the rotation detection means. 5. The turn according to claim 1, wherein when the stop of rotation of the turntable is detected, the unlocking operation of the disc opening / closing lid covering the disc storage portion is made possible. Table rotation stop detection circuit. 6. The turntable rotation stop detection circuit according to claim 1, wherein the rotation stop is displayed on the display means when the rotation stop of the turntable is detected. 7. A light emitting diode is used as a display means,
7. The turntable rotation stop detection circuit according to claim 6, wherein the rotation stop is displayed by the light emitting operation of the light emitting diode. 8. The turntable rotation stop detection circuit according to claim 6, wherein a liquid crystal is used as the display means, and the rotation stop is displayed by the liquid crystal. 9. The turntable rotation stop detection circuit according to claim 8, wherein rotation stop is displayed by a character displayed on the liquid crystal.