JPS62250525A - High speed random access method - Google Patents

Abstract

PURPOSE:To prevent the vibration of an optical system or an actuator by designing the device that the tracking servo control is released while the optical system is traversed at a high speed and the optical system is kept biased to one end of the tracking control or to the neutral state of the tracking control. CONSTITUTION:In turning off the tracking control and turning on either of tracking coils before or after at the random access, a holder 3 is driven and the movement is regulated while a slide plate 53 is depressed by a call 52. Let the displacement of the optical system 2 from the midpoint of the optical axis be () in this state, then the random access is executed and when it is detected that the head reaches a track in excess of an object track by (d), the access coil is turned off. The tracking coil is turned off simultaneously or about that time to release the regulation, then the tracking control is turned on, and an object track is detected by the conventional tracking control to complete the random access.

Description

[Detailed description of the invention] "Industrial application field" All day long, Rinbinkodo Hibutsuki day is a light beam pickup that optically reads the signal of a recording medium such as a disk or guard with a P bell tube. More specifically, the present invention relates to a high-speed random access method that prevents the optical system from vibrating in the tracking direction when the entire optical pickup moves at high speed in the tracking direction such as random access, that is, performs traverse movement.

``Prior art'' In order to prevent vibrations from occurring in the optical system and actuator when the optical system of the optical pickup amplifier traverses at high speed, it is necessary to make the acceleration and deceleration characteristics of the optical pickup amplifier gentler. A method is proposed.

``Problems to be Solved by the Inventionj'' However, in order to perform traverse movement even faster, it is necessary to have even more rapid acceleration and deceleration characteristics.

``Means for Solving the Problems'' The present invention is designed to minimize vibrations (at least magneto-optical recording or optical recording In random access of an optical pickup, which includes an optical system that optically reads signals from a recording medium such as a disk or card, and an actuator that performs focus control and tracking control of this optical system, this optical Tracking control is canceled while system focus control is allowed, and the optical system in the parentheses is regulated so that it is perpendicular to its optical axis and does not move in the random access direction, and in this regulated state, random access, i.e. We propose a high-speed random access method that performs traverse movement, releases the restricted state at or near the end point, and restores tracking control at the same time or in succession.

"Function" According to the random access method for optical pickup of the present invention, tracking servo control is canceled while the optical system is moving in traverse at high speed, and the tracking servo control is canceled when the optical system is in the midpoint state of the tracking control or biased toward one end of the tracking control. By holding the optical system in this state, vibration of the optical system is prevented, and when the traverse movement is completed, this holding state is released and tracking servo control is activated.

"Example" The present invention will be described in detail below using the drawings.

FIG. 1 is a schematic diagram of an optical pickup showing an embodiment of the present invention, FIG. 1A is a top view thereof, and FIG.
'It is a sectional view. Fig. 2 is a block diagram showing the control system of the embodiment shown in Fig. 1, Fig. 3 is a j70-chart showing its control operation, and Fig. 4 is its access time chart, showing a comparison with the conventional one. ing. Figure 5 shows another embodiment of the present invention, Figure (a) is a schematic perspective view thereof, Figure (b) Fi
Its top view, Figure (b)', is the operating state diagram of Figure (b), Figure (
c) is a partially enlarged view, and FIG. 6 is a flowchart showing the control operation.

Fig. 7 shows a conventional .
) is its perspective view, figure (b) is its top view, and figure (c
) is a cross-sectional view of the person A.

First, conventional optical backup and its random access will be explained using FIG. In Figure 7, l
is an optical pickup, which is moved in the tracking direction of the disk or card by a traverse drive mechanism 21 shown in FIG. 2 or the like. Reference numeral 2 denotes an optical system for optically reading signals, which is fixed to the holder 3, and is connected to a support post of the substrate 5 by a ring spring 4 having a buffering effect. 6 is a focus magnet fixed to the substrate 5, and 6' is a focus coil fixed to the holder 3, which allows the holder 3 to connect to the shaft 8 fixed to the substrate 5 and the bearing fixed to the holder 3. 9 and drives the optical system 2 in the optical axis direction to perform focus control. 7 is a travking magnet fixed to the substrate 5, and 7' is a travking coil provided to the holder 3. These rotate the holder 3 around the axis 8, and move the optical system 2 in the optical axis direction. Tracking control is performed by driving in the vertical tracking direction.

Next, embodiments of the present invention will be described using FIGS. 1 to 4. In each figure, the same members are given the same reference numerals. To explain the differences between FIG. 1 and FIG. 7, 1'o is an electromagnetic core fixed to the support of the substrate 5, and 11 is an excitation coil that excites this electromagnetic core. 12 is a yoke fixed to the holder 3, the width of which is approximately equal to 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 both the vertical direction; The difference is greater than the amount of focus movement of the optical system 5. These electromagnets are disposed at both ends or at one end of a line connecting the axis 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 current flows through the excitation coil 11, the electromagnetic core 10 acts to attract the yoke 12, but the movement of the holder 3 is restricted so that it cannot rotate. However, since the yoke is longer than the electromagnetic core 10 in the vertical direction, the holder 3, that is, the optical path system 2, is movable in the optical axis direction even in this state, and focus control is possible. FIG. 2 shows the control system of the optical recirculation of the embodiment shown in FIG.
The explanation of the above will be omitted, and only the parts directly related to the present invention will be explained with reference to the flowchart of FIG. First, when the target track is input from the input circuit 29 and the tracking signal indicating the current position from the optical pickup is input to the arithmetic circuit 23, the amount of movement of the track to which the optical pickup should jump is calculated (step A). (hereinafter simply referred to as A), and CB), where it is determined whether this amount of movement is greater than or equal to a specified value. When it is below the specified value, normal tracking servo or normal traverse movement is performed (the C10 movement amount is the specified value; if it is above the specified value, first turn off the tracking control and move the optical system 2 to the center position using the ring spring 4. A current is applied to the excitation coil 11 in the state of
Then, or immediately after that, the access control circuit is turned on and high-speed random access is performed. Then, while checking and checking whether the target track has been reached, the entire pickup and sock continues to move at high speed ◎, and when the target track is reached, the current to the access coil is turned off to 0, then or one after another. σ) to turn off the excitation coil control circuit and restore tracking control. Since tracking signal detection is necessary even during random access, the focus control system continues to operate at all times. From this stage, normal tracking control is resumed, tracking jumps continue (J, N, L), and random access ends.

In the above description, the specified value of the movement amount is set to the maximum movement amount of tracking control or more.

) When it is smaller than that, it can be covered by tracking servo, and when it moves by a small amount, it can be covered by excitation coil?
This is because activating it actually hinders speeding up. By performing random access using the method described above, for example, as schematically shown in FIG.
Compared to the conventional access shown in ), high-speed access as shown in Figure cb) can be obtained.

Next, a second embodiment of the optical pickup used in the present invention will be explained using FIG. 5, FIG. 6, and FIG. I will only explain about.

In FIG. 5, reference numeral 50 denotes a support column fixed to the base plate 5, and as shown in FIG.
It is located inside and is pressed toward the front plate by a leaf spring 54.

54 is a sliding plate fixed to the surface of the holder 2 facing the ball 52. In such a configuration, if an excitation current flows to only one of the trunking magnets during random access and the holder 3 is activated, the holder 3
The sliding plate 53 slides on the ball 52. 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 ball 52 slide up and down with low friction.

Next, the control of this embodiment will be explained using FIG. 5, FIG. 6, and FIG. 2.
The accompanying example is a bit confusing, and only the different parts will be explained. When performing random access, turn off the tracking control (A, B, D) or turn on one of the trunking coils at the same time.
When this is done, the holder 3 rotates and its movement is restricted with the sliding plate 53 pressed against the ball 52 (, IE'). The amount of movement of the optical system 2 from the midpoint of the optical axis in this state is assumed to be d (FIG. 5(b)'). Random access is performed in this state [F], and when it detects that it has reached a track d distance from the target track (G), the access coil is turned OFF'F. Please turn off the coil and release the restriction.I/)
Then, the tracking control is turned on (σ), and thereafter the target track is detected by normal tracking control and the random access is ended. In the above explanation, various configurations are possible for the mechanical part within the range that is obvious from this example, and regarding the operation, the ON and OFF of the control system can be set at appropriate times in relation to the mechanical operation. I can do it.

[Effects of the Invention] According to the present invention, even when the entire optical pickup is traversed at high speed by the traverse mechanism, stable and high-speed random access control can be performed without generating vibrations in the optical system or actuator.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical pickup used in an embodiment of the present invention, and FIG. 1(a) is a top view thereof, and FIG. 1(b) is a sectional view taken along line 8-N. FIG. 2 is a block diagram showing the control system of the embodiment shown in FIG. 1, FIG. 3 is a 70-chart showing its control operation, and FIG. 4 is its access time lead.
A comparison is shown between the conventional figure C (a)) and the present invention figure C (b)). 5 shows an optical pickup according to another embodiment of the present invention, FIG. 5(a) is a perspective view thereof, FIG. 5(b) is a top view thereof, c.
) is a sectional view taken along line A-A' in Figure (b), Figure (d) is a partially enlarged view, and Figure 6 is a flowchart showing its control operation. , Figure (a) is its perspective view, Figure (b) is its top view, and Figure (c) is its AA' sectional view. 1... Optical pickup 2... Optical system 3... Holder 4... Ring spring 5... Board
6... Focus magnet σ... Focus coil

Claims (1)

[Claims] In random access of an optical pickup that includes at least an optical system that optically reads signals from a recording medium and an actuator that performs focus control and tracking control of this optical system, focus control of the optical system is allowed at the starting point of the random access. Tracking control is released, the optical system is restricted from moving in the random access direction perpendicular to its optical axis, random access is performed in this restricted state, and at the end point or near the end point, the previous restricted state is released and the movement of the optical system in the random access direction is restricted. A high-speed random access method characterized by restoring tracking control.