JPH0883429A - Optical disk reproducing device and its pickup moving control method - Google Patents

Abstract

PURPOSE: To correctly make a pickup move to a target position or to the vicinity of the position without being influenced by track pitches of an optical disk in a control method for moving the pickup to the target position at the time of high speed special reproducings such as searching or the like. CONSTITUTION: Distance-time information indicating the relation between the moving distance of a pickup 2 and its required moving time are prepaired and, when the target position of the pickup 2 is shown, the distance Y between the current position of the pickup 2 and the target position is found and is controlled so that the pickup 2 is moved for a time X by deciding the time X required for moving the pickup 2 in the distance Y based on the distance-time information. Moreover, the distance-time information is updated from the error between the position of the pickup 2 posterior to the movement and the target position and then optimum distance-time information in which a secular change, etc., are considered is secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus for reproducing an optical disk such as a CD (compact disk) and a CD-ROM, and a pickup movement control method thereof.

[0002]

2. Description of the Related Art Conventionally, in an optical disk reproducing apparatus, when the pickup is moved to a desired position on the optical disk, an electric ripple waveform in an RF signal generated when the pickup crosses a track is detected. The number of tracks traversed is counted, the movement arrival position (movement distance) of the pickup is determined based on this count value, and the pickup is guided to the target position.

In this method, how accurately the ripple waveform can be detected from the RF signal is the key to accuracy. However, in recent years, the track pitch of optical discs is becoming narrower due to higher density, and it is becoming difficult to accurately detect the ripple waveform. This is because the ripple waveform in the RF signal generated when the pickup traverses the track has a lower level (waveform amplitude) as the track pitch becomes narrower if the moving speed of the pickup when reading information from the optical disk is the same. Therefore, when the pickup is moved at high speed during special reproduction such as high-speed search, the ripple waveform does not occur at a sufficient level for detection. As a result, the number of tracks crossed by the pickup is incorrect, and the pickup cannot be correctly moved to the target position.

In order to solve this problem, a method of slowing down the moving speed of the pickup can be considered, but this is not a good idea because the special playback speed for searching or the like becomes slower.

As another method, a moving distance detector such as a tack is attached to a carriage carrying a pickup, and the moving distance detector is used to measure the moving distance of the pickup during high speed special reproduction such as search. Therefore, a method of controlling the movement of the pickup without relying on the ripple waveform information has been proposed.

However, this method requires high accuracy in mounting the moving distance detector, and increases the cost due to the addition of parts for the moving distance detector.

[0007]

As described above, the conventional optical disk reproducing apparatus detects the ripple waveform in the RF signal when the pickup crosses the track in the movement control of the pickup during high-speed special reproduction such as search. It was counting to determine the movement arrival position (movement distance) of the pickup. However, according to this method, unless the moving speed of the pickup is decreased, the detection accuracy of the ripple waveform deteriorates as the track pitch of the optical disc becomes narrower, and the pickup cannot be correctly moved to the target position.

The present invention is intended to solve such a problem, and an optical disk reproducing apparatus and its pickup capable of accurately moving the pickup to a target position or its vicinity without being influenced by the track pitch of the optical disk. The purpose is to provide a movement control method.

[0009]

In order to achieve the above-mentioned object, the present invention stores a memory in which distance-time information indicating a relationship between a moving distance and a required moving time when a pickup is moved by a feed mechanism is stored. Means and a target position to which the pickup is moved, the distance between the current position of the pickup and the target position is calculated, and the time required to move the calculated distance is stored in the storage means. Based on the obtained distance-time information, there is provided control means for controlling the feed mechanism so as to move the pickup by the obtained time.

In addition, the present invention comprises a correction means for detecting an error between the position after the movement of the pickup and the target position and correcting the distance-time information stored in the storage means based on this error. I will do it.

Further, according to the present invention, after the main power is turned on, the pickup is moved from the initial setting position for a predetermined time, the error between the position after the movement and the target position corresponding to the movement time is obtained, and this error is calculated. Based on the distance-time information stored in the storage means, another correction means is provided.

[0012]

According to the present invention, the control means calculates the distance between the current position of the pickup and the target position when the target position, which is the destination of the pickup, is designated, and moves the calculated distance. The time is obtained based on the distance-time information stored in the storage means, and the feed mechanism is controlled so that the pickup is moved by the obtained time. Distance −
The time information indicates the relationship between the moving distance and the required moving time when the pickup is moved by the feed mechanism.If the content of this distance-time information is correct, the current position and target position of the pickup are shown. Based on the distance-time information, it is possible to know the correct moving time required to move the distance between and, and it is possible to reliably move the pickup to or near the target position.

Further, the correction means detects an error between the position after the movement of the pickup and the target position and corrects the distance-time information stored in the storage means based on this error, so that the pickup changes due to secular change or the like. Even if there is a change in the operating state of the feeding mechanism, the correct distance-time information can always be held.

Further, another correcting means moves the pickup from the initial setting position for a predetermined time after the main power is turned on, that is, before the high speed special reproduction such as the search operation is performed, and the position after the movement is moved. The distance-time information stored in the storage means is corrected on the basis of the error with respect to the target position corresponding to time, so that even if there is a change in the operating state of the pickup feed mechanism due to aging or the like. , It is possible to always keep correct distance-time information.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall structure of an optical disk reproducing apparatus according to an embodiment of the present invention.

In the figure, on the optical disc 1 shown in FIG. 1, information is recorded in units of sectors, and tracks, which are a group of one sector of the sector, are arranged at a constant pitch along the disc radial direction. There is. An optical pickup 2 irradiates the optical disc 1 with a laser beam and reads the intensity of the reflected light as a reproduction signal. The optical pickup 2 can be moved in a direction indicated by an arrow by a pickup feeding mechanism (not shown), that is, in a direction traversing the track T on the optical disc 1 as shown in FIG.
A data slicer 3 obtains a binary signal by subjecting the output RF signal of the optical pickup 2 to waveform equalization, data slicing and the like. A PLL circuit 4 generates a clock for data reproduction from the binary signal output from the data slicer 3. Reference numeral 5 is a demodulation / error correction circuit for performing demodulation and error correction on the reproduction data taken in from the binary signal sequence using the clock. Reference numeral 6 is a drive circuit for driving the pickup feed mechanism. Reference numeral 7 denotes a microprocessor unit (hereinafter, referred to as MPU) that controls the entire apparatus, including a CPU.
The program executed by the CPU and a ROM in which various data are fixedly stored are further included, and a nonvolatile memory such as an EEPROM for storing a distance-time table described later is included. Although not shown in the figure, the present apparatus is also configured to have a disk drive system, various servo systems, and the like.

The MPU 7 performs the following pickup movement control according to a predetermined program in the ROM. The details will be described below.

In FIG. 3, when the pickup 2 is moved from the position shown in the figure (initial setting position) in the direction of the arrow at the speed of high speed special reproduction, the relationship between the moving distance and the required moving time is shown in FIG. 4, for example. It will be as shown.

Therefore, if the information indicating the relationship between the moving distance and the required moving time is prepared in advance, when the target position, which is the moving destination of the pickup 2, is designated, the current position of the pickup 2 and the target. From the distance to the position and the above information, the time required for the pickup 2 to move to the target position can be obtained, and the movement distance of the pickup 2 can be controlled almost accurately with time.

In order to specifically realize the pickup movement control by such time, accurate information indicating the relationship between the above-mentioned movement distance and the required movement time is required. However, the relationship between the distance and the time varies slightly depending on the product even for the same type of device, and the relationship changes from time to time due to aging.

In consideration of such circumstances, in the present embodiment, a distance-time table showing the relationship between the moving distance and the required moving time for each product is prepared by the manufacturer before shipment of the device, and this is stored in the MPU 7. It is supposed to be recorded in the non-volatile memory.

A specific example method for creating this distance-time table will be described below. For example, as shown in FIG. 3, there are a plurality of points (for example, A, B, C, and D 4) between the innermost track and the outermost track on the optical disc 1.
Points), and for each point, the pickup 2 is moved from the position shown in the figure (initial setting position) to the target in the arrow direction at the speed during high-speed special reproduction. The movement at this time is performed by moving the pickup 2 for a preset time for each point.
That is, first, the pickup 2 is moved from the initial setting position for the set time with the point A as the target. After the movement, the track / sector information recorded on the optical disc 1 is detected to check to which position on the optical disc 1 the pickup 2 has actually moved. Then, the error between the actual movement position and the target position (point A) is detected, and the set time is corrected based on this error. Next, the pickup 2 is moved from its initial position to the point B for the set time, the error between the actual movement position and the target position (point B) is detected in the same manner, and the point B with respect to the point B is detected based on this error value. Correct the set time. Hereinafter, similarly, the same processing is performed for each of the points C and D.

The above-described correction of the set time for each point is repeatedly performed for one point a plurality of times, and the average value is set for each point as the final set time before product shipment. Then, the distance-time table is created from the set time for each point.

As described above, the distance-time table in consideration of the variation of each product is prepared. In addition to this, in the present embodiment, the secular change of the operation state of the pickup feeding mechanism is mainly taken into consideration. The contents of the distance-time table can be corrected by the user. This operation will be described below.

When the main power is turned on to the device, the MPU 7
Reads the content of the distance-time table from the non-volatile memory and approximates the relationship between the distance and time. Immediately after the optical disc 1 is loaded in the device, the MPU 7 immediately executes the same operation as the test movement of the pickup 2 performed before the product shipment based on the above-described mathematical relationship between distance and time. And the actual pickup 2 for each point
The relationship between the distance and the time calculated above is corrected based on the error between the moving position and the target position.

After that, when the target position of the pickup 2 is designated for high speed special reproduction such as search operation, the MPU
Reference numeral 7 obtains the distance Y from the current position of the pickup 2 to the target position, and obtains the time X required to move the distance Y from the above formula. Then, the pickup 2 is moved by the obtained time X, the track / sector information is detected at that position, and the error from the target position is determined.

If the error is zero in this determination, the information is read from the optical disc 1 as it is. If there is an error, the pickup 2 is moved at a low speed, the ripple waveform in the RF signal generated when the pickup 2 crosses the track is detected, and the pickup 2 is moved to the target position. Then, the contents of the distance-time table are corrected again from the above error.

As described above, it becomes possible to move the pickup 2 at once to the target position or its vicinity irrespective of the ripple waveform information when the pickup 2 crosses a track, and for the optical disc 1 having a narrow track pitch. However, the pickup can be moved to the target position or its vicinity in a good and accurate manner.

When the pickup 2 is moved to the target position, it is necessary to reversely drive the feed motor and brake the motor before the pickup 2 reaches the target position, as shown in FIG. Therefore, specifically, a time point X1 at which the feed motor is reversely driven is obtained from the required travel time X with respect to the travel distance, and the feed motor is reversely driven at the time point X1 to finally reach the required travel time X. At this point the motor must be stopped.

[0031]

As described above, according to the present invention, when the target position to which the pickup is moved is designated, the distance between the current position of the pickup and the target position is calculated,
Obtaining the time required to move this calculated distance,
The pickup can be moved only during this time, which allows the pickup to be accurately moved to or near the target position without being influenced by the track pitch of the optical disc.

Further, according to the present invention, distance-time information indicating the relationship between the movement distance and the movement required time when the pickup is moved by the feed mechanism is further added based on the error between the movement position of the pickup and the target position. Is corrected based on the error between the pickup movement position and the target position obtained by the test movement of the pickup after the main power is turned on, so even if there is a change in the operation state of the pickup feed mechanism due to aging, etc. The correct distance-time information can be sequentially updated, and the accuracy of the pickup movement can be ensured as much as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an optical disc reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a relationship between an optical disc and a pickup in the optical disc reproducing device of FIG.

FIG. 3 is a diagram for explaining a specific method for creating a distance-time table.

FIG. 4 is a graph showing a relationship between a moving distance of a pickup and a required moving time thereof.

FIG. 5 is a diagram showing how a motor is driven when moving a pickup to a target position.

[Description of Codes] 1 ... Optical disc, 2 ... Optical pickup, 3 ... Data slicer, 4 ... PLL circuit, 5 ... Demodulation / error correction circuit, 6
… Driving circuit, 7… Microprocessor unit (MP
U).

Claims (4)

[Claims] 1. A pickup for reading information recorded on an optical disc, a feed mechanism for moving the pickup on the optical disc in a direction traversing a track of the optical disc, and a feed mechanism for moving the pickup by the feed mechanism. A storage unit storing distance-time information indicating a relationship between a moving distance and a required travel time, and a distance between a current position of the pickup and the target position when a target position to which the pickup is moved is designated. Is calculated, and the time required to move the calculated distance is calculated based on the distance-time information stored in the storage means, and the feed mechanism is controlled to move the pickup by the calculated time. An optical disk reproducing apparatus comprising: a control unit. 2. The optical disc reproducing apparatus according to claim 1, wherein an error between a position after the movement of the pickup and the target position is detected, and distance-time information stored in the storage means is based on the error. An optical disk reproducing apparatus, further comprising a correcting unit for correcting. 3. The optical disk reproducing apparatus according to claim 1, wherein after the main power is turned on, the pickup is moved from an initial setting position for a predetermined time, and an error between a position after the movement and a target position corresponding to the movement time. The optical disc reproducing apparatus further comprising a correction unit that determines the distance-time information stored in the storage unit based on the error. 4. A pickup for reading information recorded on an optical disc, a feed mechanism for moving the pickup on the optical disc in a direction traversing a track of the optical disc, and a pickup mechanism for moving the pickup by the feed mechanism. In an optical disc reproducing apparatus having a storage unit in which distance-time information indicating a relationship between a moving distance and a required moving time is stored, when a target position, which is a moving destination of the pickup, is designated, a current position of the pickup is displayed. The distance to the target position is calculated, the time required to move the calculated distance is calculated based on the distance-time information stored in the storage unit, and the pickup is moved by the calculated time. A pickup movement control method comprising controlling the feed mechanism.