JPS6252732A - Track access system - Google Patents

Abstract

PURPOSE:To attain accurate track access in a short time by providing a means moving an optical head in a direction at a nearly right angle to the light beam and applying an inverse drive signal to the optical head moving direction to the moving means at the end of movement the head so as to overpath of the head to the object position of the light beam at the head damping. CONSTITUTION:The optical head 4 is moved radially to the optical disc 1 and arranged to the upper side of a carriage 5 acting like an optical beam moving means and moved attended with the movement of the carriage 5. At random access, a speed curve is formed depending on the accessed distance and the carriage 5 is moved along with the speed curve. When the carriage 5 reaches an object position or a point by a little, a control signal is applied to exert a reverse torque to the moving direction of the carriage 5 to the tracking actuator. Thus, even when the light head is moved, the light beam is stopped instantly and the access is finished by applying tracking servo. Thus, high speed access is applied.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a track access method, in particular, to a track access method, in which a light beam is irradiated onto an information carrier having a plurality of optically distinguishable tracks, thereby recording or reproducing information. The present invention relates to a track access method in an optical information recording/reproducing apparatus that performs one or both of the above methods.

[Prior Art] In an information carrier such as an optical disk, a plurality of information tracks are usually formed in a row by unevenness or the like.

The information tracks are arranged, for example, concentrically or spirally on the surface of the optical disk.

When recording information on such an information carrier, an information track is traced by a light beam that is modulated according to the information. When reproducing information recorded on an information carrier, an unmodulated light beam is irradiated onto the information track, and the information is read by detecting the amount of the light beam irradiated onto the information track.

Further, in such an optical information recording/reproducing device, tracking control for accurately following an information track with a light beam and a track access method for irradiating a desired track with a light beam are essential.

By the way, in the conventional track access method, first the approximate position of the optical head is determined using an external scale, such as a near encoder, and then detailed positioning is performed by driving an actuator that is a means for moving the optical beam. A method is known in which a beam spot is directed to a target track position by using the following method.

To explain this method in more detail, the target traffic
To access the 7th position, first find the track position illuminated by the beam spot, and drive the linear motor approximately the distance calculated from this track position to the target track using the linear encoder as an index. Decide on the target and aim the beam spot at the nearby Torara/Ri.

After determining the approximate position in this way.

Check again the track position where the beam spot is irradiated.

And to move it accurately to the desired track position,
This is done by driving the tracking actuator of the optical head.

The light beam moves as the tracking actuator is driven, and when it reaches the desired track position, access is completed.

[Problems to be Solved by the Invention] However, according to the above method, the light beam may exceed the target position due to inertial force when the optical head is braked.

Therefore, it is necessary to wait until the optical head is selected before starting the next operation, and there is a problem that access takes a considerable amount of time.

The present invention has been made in view of the above circumstances, and includes a light beam moving means for moving the optical head in a direction substantially perpendicular to the light beam, and when the head movement is completed, the light beam moving means is moved in the opposite direction to the optical head moving direction. By applying a driving signal in the direction, the purpose is to prevent the optical beam from exceeding the target position when braking the optical head, and to perform accurate track access in a short time.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and it irradiates a recording medium consisting of a plurality of information tracks with a light beam, and moves an optical head to read the information. In a track access method in which the optical head is moved relative to the track in a direction substantially perpendicular to the track and irradiates the desired information track with the light beam, the optical head is provided with a light beam moving means for moving the optical head in a direction substantially perpendicular to the light beam; The present invention provides a track access method characterized in that a drive signal in a direction opposite to the optical head moving direction is applied to the optical beam moving means at the end of the movement.

[Function] By using the above means, the present invention can provide an accurate track access method that allows adjustment in a short time by simple operations.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a schematic diagram of an optical disk device.

In FIG. 1, reference numeral 1 denotes an optical disk, and this optical disk is equipped with a seven-head motor 2 that is driven and rotated at, for example, 1800 r, p, m, and this motor 2 is attached to the optical disk 1 via a motor shaft 3.

An optical disc 4, which supplies a light beam and records, reproduces or erases information, moves in the radial direction of the optical disc l, and is disposed above a carriage 5, which functions as a light beam j# moving means. 3 moves with the movement of 5
6. When recording, playing and erasing information,
Tracking servo can be applied by the tracking actuator of the Hikari Rad 4.

At this time, the position of the carriage 5 is controlled so that the tracking actuator is approximately neutral.

For example, when the tracks of the optical disc 1 are formed in a spiral shape, the carriage 5 is slowly moved in the inner circumference or multiple circumference directions of the track traced by the light beam.

During random access, a speed curve is created according to the access distance, and the carriage 5 is moved according to this speed curve.

The speed curve at this time is shown in FIG. 2(A). This velocity curve is set so that it still has a predetermined velocity at the target position.

The carriage 5 moves along this speed curve, but when it reaches the target position or a little before it reaches the target position, it reaches the target position (Figure 2 CB).
A control signal is applied so that a driving force in the direction opposite to the moving direction of the carriage 5 is applied to the tracking actuator as shown in FIG. In this way, even if the optical head moves,
The light beam immediately stops as shown in FIG. 2(C), and tracking servo is applied to complete the access.

As described above, in this embodiment, high-speed access is possible by applying braking force to the track actuator upon arrival at the destination position.

The target track is detected by a counting means that counts tracking error signals, or by a recognition means that can analyze and determine the track number at a time when the carriage is moving at a low speed.

Note that the M11 signal upon arrival at the destination position may be superimposed on the carriage drive signal, thereby allowing high-speed access.

Furthermore, the detection of the target position t is performed using a tracking cross signal, but when this tracking cross signal is counted by, for example, a flip-flop circuit, the moving speed of the optical head becomes slow and the light beam is distorted due to the influence of deviation. A phenomenon of crossing the track in the opposite direction may occur, causing an error in the above-mentioned counting. Even in such a case, according to the embodiment described above, the moving speed of the optical head can be controlled at the target position, so that the above-mentioned inconvenience can be prevented.

[Effects of the Invention] As described above, the present invention includes a light beam moving means for moving the optical head in a direction substantially perpendicular to the light beam,
By applying a drive signal in the opposite direction to the optical head movement direction to the optical beam moving means at the end of each movement, the optical beam is prevented from exceeding the target position when the optical head is braked, and accurate track access is achieved in a short time. can be done.

Furthermore, when the tracking crossing signal is counted by, for example, a flip-flop circuit, the moving speed of the optical head becomes slow, and a phenomenon occurs in which the optical beam crosses the track in the opposite direction due to the influence of deviation, resulting in an error in the above-mentioned counting. However, since the moving speed of the optical head can be controlled at the target position, such inconveniences can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical disk device, FIG. 2 (A) is a diagram showing the relationship between carriage speed and required time, and FIG. 2 (B) is a timing diagram showing the relationship between actuator drive signal and required time. FIG. 2(C) is a diagram showing the relationship between the speed of the light beam and the main time. Explanation of the symbol 1 indicates the recording medium 4 and the light beam moving means 1. Figure 2. Procedural amendment document January 17, 1985 Michibe Uga, Commissioner of the Patent Office 1. Indication of the case Patent application No. 1984-1984 2. Invention Name Track Access Method 3 Relationship with the person making the amendment Patent applicant name (100) Canon Co., Ltd. 4 Agent address 40 Toranomon, 5-13-1 Toranomon, Minato-ku, Tokyo
Mori Building Name (6538) Patent Attorney Sekihei Yamashita! '7 End' 5 Target of correction
+r:'::r=Drawing 6 Details of correction Figures 2 (A) to (C) will be corrected as shown in the attached sheet. -2 Figure 2

Claims (1)

[Claims] In a track access method, a recording medium consisting of a plurality of information tracks is irradiated with a light beam, an optical head is moved relative to the information track in a direction substantially perpendicular to the information track, and the light beam is irradiated onto a desired information track. It is characterized by comprising a light beam moving means for moving the head in a direction substantially perpendicular to the light beam, and applying a drive signal in the opposite direction to the moving direction of the optical head to the light beam moving means when the head movement is completed. Track access method.