JPH0746426B2 - High-speed random access method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-speed random access method for an optical pickup that optically reads a signal from a recording medium such as a disk or a guard on which magneto-optical recording or optical recording is performed. More specifically, it relates to a high-speed random access method for preventing the optical system from vibrating in the tracking direction when the entire optical pickup moves at a high speed in the tracking direction such as random access, that is, traverse movement.

"Prior Art" Conventionally, in order to prevent vibration of the optical system and actuator when the optical system of the optical pickup traverses at a high speed, there is a method such as grading the acceleration and deceleration characteristics of the optical pickup. Proposed.

“Problems to be solved by the invention” However, in order to perform traverse movement at a higher speed, it is necessary to have characteristics of further rapid acceleration and deceleration.

"Means for Solving the Problems" The present invention does not cause vibration in the optical system or the actuator even when the entire optical pickup traverses at a high speed by the traverse mechanism. In a random access of an optical pickup including an optical system for optically reading a signal of a recorded recording medium such as a disc or a card and an actuator for performing focus control and tracking control of the optical system, this optical system is used at the starting point of the random access. Tracking control is released with focus control allowed, and the optical system is restricted from moving in the random access direction perpendicular to its optical axis. Move, and then move at or near the end point. We propose a high-speed random access method that cancels the restriction state and recovers the tracking control at the same time or in tandem with it.

[Operation] According to the random access method of the optical pickup of the present invention, the tracking servo control is canceled during the traverse movement of the optical system at a high speed, and the tracking control is in the middle point state or in the state in which the tracking control is biased to one end. The holding of the optical system prevents the optical system from vibrating, and when the traverse movement ends, the holding state is released and the tracking servo control operates.

[Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an optical pickup showing an embodiment of the present invention, FIG. 1 (a) is a top view thereof, and FIG. 1 (b) is its AA 'sectional view. FIG. 2 is a block diagram showing the control system of the embodiment shown in FIG. 1, FIG. 3 is a flow chart showing its control operation, and FIG.
The figure is the access time chart and shows a comparison with the conventional one. FIG. 5 shows another embodiment of the present invention, FIG. 5A is a schematic perspective view thereof, and FIG. 5B is a top view thereof.
FIG. 6 (c) is an operation state diagram of FIG. 7 (b), FIG. 6 (d) is a partially enlarged view thereof, and FIG. 6 is a flowchart showing its control operation. FIG. 7 shows a conventional optical pickup, FIG. 7 (a) is a perspective view thereof, FIG. 7 (b) is a top view thereof, and FIG. 7 (c) is an AA 'sectional view thereof.

First, a conventional optical pickup and its random access will be described with reference to FIG. In FIG. 7, 1
Is an optical pickup, which is moved in the tracking direction of the disk or card by the traverse drive mechanism 21 shown in FIG. Reference numeral 2 denotes an optical system for optically reading a signal, which is fixed to a holder 3 and is connected to a column 5'of a substrate 5 by a ring spring 4 having a cushioning effect. 6 is a focus magnet fixed to the substrate 5,
6'is a focus coil fixed to the holder 3,
By these, the holder 3 moves in the axial direction of the shaft 8 fixed to the substrate 5 and the bearing 9 fixed to the holder 3 to move the optical system 2
Is driven in the optical axis direction to perform focus control. Reference numeral 7 denotes a tracking magnet fixedly mounted on the substrate 5, 7'denotes a tracking coil provided on the holder 3, whereby the holder 3 rotates about an axis 8 to move the optical system 2 in a tracking direction perpendicular to the optical axis direction. To perform tracking control.

Next, an embodiment of the present invention will be described with reference to FIGS. In each drawing, the same members are designated by the same reference numerals. In FIG. 1, what is different from FIG. 7 will be described. Reference numeral 10 is an electromagnet core fixed to a support of the substrate 5, and 11 is an exciting coil for exciting the electromagnet core. Reference numeral 12 denotes a yoke fixed to the holder 3, the width of which is substantially the same as the width of the electromagnet core 10, and the length of the optical system 2 in the optical axis direction is longer than the length of the electromagnet core 10 in the vertical direction. The difference is more than the focus movement amount of the optical system 5.
These electromagnets are arranged at both ends or either end on a line connecting the shaft 8 of the holder 3 and the optical axis of the optical system 2 and at a position close to a position facing the electromagnet core 10. Therefore, when a current flows through the exciting coil 11, the electromagnet core 10 acts so as to attract the yoke 12, so that the holder 3
Movement is restricted so that it cannot rotate. However, since the yoke is longer than the electromagnet core 10 in the vertical direction, even in this state, the holder 3, that is, the optical system 2 is movable in the optical axis direction, and focus control is possible. FIG. 2 shows the control system of the optical pickup of the embodiment of FIG.
Since the parts other than 28 are well known, the description thereof will be omitted, and only the part directly related to the present invention will be described with the flowchart of FIG. First, when a target track is input from the input circuit 29 and a tracking signal indicating the current position from the optical pickup is input to the arithmetic circuit 23, the movement amount of the track to which the optical pickup should jump is calculated (A step, Hereinafter, it will be referred to only as A), and it is further determined here whether this movement amount is a specified value or more (B). When it is less than the specified value, normal tracking servo or normal traverse movement is performed (C). When the amount of movement is above the specified value, first turn off tracking control.
(D), current is passed through the exciting coil 11 in a state where the optical system 2 is at the center position by the ring spring 4, and the movement of the optical system 2 is regulated so as to be fixed (E). And turn on the access coil control circuit (F),
Provides fast random access. Then, while checking whether or not the target track has been reached, the entire pickup continues to move at high speed (G), and when it reaches the target track, the current to the access coil is turned off (H), and after that or before or after it, it is excited. The coil control circuit is turned off (I), and the tracking control is restored (J). Since the tracking signal needs to be detected even during random access, the focus control system is constantly operating. From this stage, the normal tracking control is restored, and thereafter the tracking jump is continued (J, K, L) and the random access is ended. In the above description, the regulation value of the movement amount is set to the maximum movement amount of the tracking control or more. This is because when it is smaller than that, it can be covered by the tracking servo, and when the movement is too small, the exciting coil is actuated, which hinders the speedup. By performing the random access by the method described above, for example, as schematically shown in FIG. 4, compared to the conventional access shown in FIG. 4A, a high speed access as shown in FIG. can get.

Next, a second embodiment of the optical pickup used in the present invention will be described with reference to FIGS. 5, 6, and 2, but the same portions as those of the first embodiment will be omitted and different portions will be described. Will be described only. In FIG. 5, reference numeral 50 designates a pillar fixed to the substrate 5. In this pillar 50, a ball 52 is provided in the hole 51a of the front plate 51 and the pillar 50 as shown in a partially enlarged view of FIG.
In the recess 50a, the leaf spring 54 presses the front plate. Reference numeral 54 is a sliding plate fixed to the surface of the holder 2 facing the ball 52. In such a configuration, when an exciting current flows through only one of the tracking magnets during random access to operate, the holder 3 rotates about the shaft 8 and its sliding plate 53 slides on the ball 52. Contact. The leaf spring 54 also acts as a damper during this sliding contact. When focus control is performed in this state, the holder 3 moves up and down, and the sliding plate 53 and the ball 52 slide up and down with low friction.

Next, the control of this embodiment will be described with reference to FIGS. 5, 6, and 2, but the same portions as those of the first embodiment shown in FIGS. 2 and 3 will be omitted and different. Only the part will be described. When performing random access, when tracking control is turned off (A, B, D) or one of the tracking coils is turned on after that, the holder 3 rotates and the sliding plate 53 presses the ball 52. The movement is restricted in the state where it is kept (E '). The amount of movement of the optical system 2 from the midpoint of the optical axis in this state is defined as d (Fig. 5 (c). In this state, random access is performed (F), and a track that has passed too much d from the target track is reached. When the arrival is detected (G), the access coil is turned off (H). Simultaneously or before or after this, the tracking coil is turned off and the regulation is released (I '), and then the tracking control is turned on.
(J), thereafter, the target track is detected by the normal tracking control and the random access is ended. Note that in the above description, various configurations are possible for the mechanical part within the scope obvious from the present embodiment, and the operation is set to ON or OFF of the control system at an appropriate time in relation to the mechanical operation. I can.

[Advantages of the Invention] According to the present invention, even when the entire optical pickup traverses at high speed by the traverse mechanism, stable and high-speed random access can be controlled without generating vibration in the optical system or the actuator.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an optical pickup used in an embodiment of the present invention. FIG. 1A is a top view thereof, and FIG.
It is a -A 'sectional view. FIG. 2 is a block diagram showing the control system of the embodiment of FIG. 1, FIG. 3 is a flow chart showing its control operation, and FIG. 4 is its access time chart. Of the present application (Fig. (B))
Shows a comparison with. FIG. 5 shows an optical pickup according to another embodiment of the present invention. FIG. 5A is a perspective view thereof, FIG. 5B is a top view thereof, and FIG. 5C is an operation state diagram of FIG. (D) is a partially enlarged view, and FIG. 6 is a flowchart showing the control operation. FIG. 7 shows a conventional pickup, FIG. 7A is a perspective view thereof, FIG. 7B is a top view thereof, and FIG. 7C is a sectional view taken along the line AA '. 1 ... Optical pickup 2 ... Optical system 3 ... Holder, 4 ... Ring spring 5 ... Substrate, 6 ... Focus magnet 6 '... Focus coil 7 ... Tracking magnet 7' ... Tracking coil, 8 …… Axis 9 …… Bearing, 10 …… Electromagnetic core 11 …… Excitation coil, 12 …… Yoke 20 …… Optical disk, 21 …… Traverse drive mechanism 28 …… Excitation coil control circuit, 50 …… Post 51 …… Previous Plate, 52 ... Ball 53 ... Sliding plate, 54 ... Leaf spring

Claims (1)

[Claims] 1. In a random access of an optical pickup including at least an optical system for optically reading a signal of a recording medium and an actuator for performing focus control and tracking control of the optical system, focus control of the optical system at a starting point of random access. And release the tracking control, and regulate the optical system or the holding member of the optical system to a predetermined position by magnetic force so as not to move in a random access direction perpendicular to the optical axis. The high-speed random access method is characterized in that the random access is performed in step S4, and the restricted state is released at or near the end point, and the tracking control is sequentially restored.