JPH0664743B2 - Protective device for information recording disk player - Google Patents

Description

TECHNICAL FIELD The present invention relates to a protection device for an information recording disc player, and more particularly to a protection device for protecting an information recording disc (hereinafter, simply referred to as a disc) and a pickup.

BACKGROUND ART Most players that reproduce information recording discs such as optical video discs and digital audio discs have a pickup located below the disc, but the pickup is located above the disc. There are also players and double-sided playback players in which a pair of pickups 100A and 100B are located on both the upper and lower sides of the disc 101 as shown in FIG. In FIG. 5, 102 is a spindle motor for rotating the disk 101, and 103 is a clamper for clamping the disk 101. 6A and 6B show a plan view and a side sectional view of the pickups 100A and 100B, and the movable portion 106 including the objective lens 104, the actuator coil 105 and the like is the magnet 10
An actuator spring 110 movably supports a fixed portion 109 including the yoke 7 and the yoke 108 in the optical axis direction.

By the way, in a player having a pickup positioned above the disc, a movable portion 106 including an objective lens 104 of the pickup is in a direction perpendicular to a recording surface of the disc by a focus servo circuit (not shown) during reproduction. The position is controlled to maintain a certain distance from the recording surface.However, when the power is turned off due to a power failure or a power switch off, the movable portion 106 of the pickup moves relative to the fixed portion 109. Actuator spring
Since it is only supported by 110, it will fall below the neutral position due to its own weight and approach the recording surface of the disc. Further, the spindle motor that rotationally drives the disk is in a free-run state in which it continues to rotate for a while due to inertia even after the power is turned off. Therefore,
If the disc is warped, the distance between the disc that continues to rotate with the spindle motor even after the power is turned off and the movable part of the pickup that has fallen below the neutral position due to its own weight cannot be kept constant, and depending on the relative position between them, It is possible that they come too close to each other and come into contact with each other, damaging the disc and the pickup.

Further, even in a pickup located below the disc, there is no guarantee that the above-mentioned contact accident never occurs, and it may occur when the disc warp is extremely large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a protection device for an information recording disk player capable of reliably protecting a disk and a pickup from a contact accident in a free running state of a spindle motor. To do.

A protection device according to the present invention includes an information recording disk player having a spindle motor for rotating and driving an information recording disk, and a pickup including a movable part and a drive means for movably supporting the movable part by a beam member and driving the same. The drive means comprises a magnetic circuit for moving the movable part by an electromagnetic force, and when the spindle motor is in a free-run state after power-off, the movable part is moved from the recording surface of the disk. It is characterized in that an electromagnetic force is generated in the magnetic circuit in order to hold the recording surface at a position separated in a direction perpendicular to the recording surface.

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, which is applied to a reproducing player using a brush motor as a spindle motor. In the figure, the motor 1A
Is driven to rotate by the drive current supplied from the motor drive circuit 3 via the changeover switch 2 when the power is turned on. A power supply voltage is supplied to the motor drive circuit 3 from a power supply unit 4 when a power switch (not shown) is turned on.
The power supply voltage from is also supplied to the pickup drive circuit 6 via the switch 5. During reproduction, the pickup drive circuit 6 supplies a drive current corresponding to a focus error signal supplied from a focus error signal generation circuit (not shown) to the pickup actuator 7 to control the position of the objective lens 104 in the optical axis direction. To do. The changeover switch 2 is switched to the a side when the power is turned on and to the b side when the power is turned off, and the switch 5 is turned on (closed) when the power is turned on.
It becomes a state.

When the power is turned off due to the power switch being turned off or a power failure during reproduction, the motor drive circuit 3 and the pickup drive circuit 6 are not supplied with the power supply voltage from the power supply unit 4, so the motor 1A is in a free-run state due to inertia. In addition, in the double-sided player shown in FIG.
The objective lens 104 of the pickup 100A positioned above 101 is lowered due to its own weight due to the neutral position and approaches the recording surface of the disc 101, and conversely, the objective lens 104B of the pickup 100B positioned below the disc 101 is It is separated from the recording surface of the disc 101. As described above, when the spindle motor is in the free-run state, the objective lens 104A of the upper pickup 100A approaches the recording surface of the disc 101, and when the disc is warped, the disc 101 and the pickup 100A come into contact with each other. An accident may occur.

Therefore, in the present embodiment, the counter electromotive voltage generated in the coil when the motor is in the free running state is used, and the pickup actuator 7 is driven by this counter electromotive voltage to move the movable part including the objective lens to, for example, the neutral position. It has a holding structure. That is, when the power switch is turned off, the changeover switch 2 is switched to the b side, so that the counter electromotive voltage generated at the motor terminal is supplied to the smoothing circuit 8 via the switch 2. Since the brush motor has a commutator, a DC (pulsating current) counter electromotive force is generated at the motor terminal.
It is supplied to the pickup drive circuit 6 after being smoothed by. The pickup drive circuit 6 supplies a drive current to the pickup actuator 7 to such an extent that the movable portion including the objective lens of the pickup can be held at, for example, the neutral position by the counter electromotive voltage supplied via the smoothing circuit 8.
FIG. 2 is a timing chart of the modes of the respective parts in FIG.

As described above, when the spindle motor is in the free-run state, the back electromotive force generated in the motor drives the pickup actuator 7 to move the movable portion of the pickup to a position separated from the recording surface of the disc by a predetermined distance, for example, a neutral position. By holding the disk, the separation distance between the disk and the pickup can be kept constant until the rotation of the disk is almost stopped, so that the disk and the pickup can be reliably protected from a contact accident in the free-run state. Further, by supplying a drive current to the pickup actuator 7 by the counter electromotive voltage generated in the motor and causing the actuator 7 to consume the generated energy (counter electromotive force) of the motor, the braking force of the electromagnetic brake of the motor can be increased. Therefore, the free run period of the motor can be shortened.

In the above embodiment, the case where the brush motor is used as the spindle motor has been described.However, when the brushless motor 1B is used, an AC counter electromotive voltage is generated in the coil in the free running state of the motor, As shown in FIG. 3, a rectifier circuit 9 may be added to rectify an AC back electromotive force and then supplied to the smoothing circuit 8, and the same effect as that of the above embodiment can be obtained.

Further, in the above-described embodiment, the pickup actuator 7 is driven by using the counter electromotive voltage generated in the motor in the free-run state, but the invention is not limited to this. For example, as shown in FIG. The capacitor 10 is connected between the output terminal of 5 and the ground, and is charged by the power supply voltage when the power is turned on, and the pickup actuator 7 is driven by the stored voltage of the capacitor 10 in the free running state of the motor after the power is turned off. It is also possible.

Furthermore, in the above-mentioned embodiment, the movable part of the pickup is held at the neutral position, but the holding position can be arbitrarily set according to the warp of the disc, and the present invention is above the disc. It is not applicable only to pickups located at the position where the spindle motor is free running, and the possibility of contact accidents between the disc and the pickup is extremely low, but for pickups located below the disc. However, it is applicable.

Furthermore, in a player having a backup power source such as a vehicle-mounted player, it is possible to provide a timer and drive the pickup actuator 7 by the backup power source only for a certain period after the main power source is turned off.

As described above, according to the protection device of the present invention,
A position having a magnetic circuit for moving the movable part of the pickup by electromagnetic force, and separating the movable part from the recording surface of the disk in a direction perpendicular to the recording surface when the spindle motor is in a free-run state after power-off. Since the magnetic circuit is configured to generate an electromagnetic force in order to hold the disk, the disk and the pickup can be reliably protected from a contact accident in the free running state of the spindle motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart of modes of respective parts in FIG. 1, FIG. 3 is a block diagram showing another embodiment of the present invention, and FIG. FIG. 5 is a block diagram showing still another embodiment of the present invention, FIG. 5 is a configuration diagram showing a positional relationship of a pair of pickups with respect to a disc in a double-sided player, FIG. 6A is a plan view of the pickups, and FIG. Is a side sectional view thereof. Explanation of symbols for main parts 1A, 1B, 102 …… Spindle motor 3 …… Motor drive circuit 6 …… Pickup drive circuit 7 …… Pickup actuator 104 …… Objective lens 105 …… Actuator coil 110 …… Actuator spring

Claims (1)

[Claims] 1. A protection of an information recording disk player having a spindle motor for rotationally driving an information recording disk, and a pickup including a movable portion and a driving means for movably supporting the movable portion by a beam member and driving the same. In the device, the driving means is composed of a magnetic circuit for moving the movable portion by an electromagnetic force, and when the spindle motor is in a free-run state after power-off, the movable portion is recorded from the recording surface of the disc. An apparatus for protecting a disk player, wherein an electromagnetic force is generated in the magnetic circuit so as to hold the magnetic circuit at positions separated in a direction perpendicular to the surface.