JPH064883A - Random access device for compact disk player - Google Patents

Abstract

PURPOSE:To enable the execution of a proper jump and to shorten the access time by correcting the next number of jumped tracks having an error between a jumped address and a target address based on the relation between a pickup position and a through time at a constant linear velocity. CONSTITUTION:A number of jumping tracks from the present address to the target address of the pickup is made jump by the number of tracks derived by means of a deriving means for the number of jumping tracks 71 based on the relation between the position of the pickup and the address at a constant linear velocity as a reference. Then, an error between the target address and the address after the jump is derived by an address error deriving means 72, when the obtained address error is larger than a prescribed value, the number of jumped tracks is corrected by means of a correcting means for the number of jumped tracks 73 according to the extent of the error. Consequently, a proper jump of a CD with a different constant linear velocity is always enabled at the time of random access and the time required for a random access is shortened.

Description

Detailed Description of the Invention

[0001]

The present invention relates to various constant linear velocities (CL
The present invention relates to a random access device for a compact disc player, which can speed up random access of a compact disc recorded in V).

[0002]

2. Description of the Related Art In a conventional compact disc player, a disc motor for rotating a compact disc (hereinafter referred to as "CD") is subjected to constant linear velocity control in order to increase the recording density of a CD. The linear velocity of this CD is 1.2 to 1.4 m / s. Since this linear velocity must be constant in all radial directions of the CD, the rotation signal of the disk motor is controlled by using the synchronizing signal stored in the CD as the velocity signal.

A random access technique is one of the features of the compact disc player. This is to move a pickup that reads information from a CD to a target position when a target position, for example, a music number of a music is input by a signal input from the outside by a signal input from the outside, for example. The random access will be described below.

FIG. 7 is a diagram for explaining conventional random access of a CD. As shown in the figure, the reflected light from the track 2-1 composed of pits stored in the CD 1 is detected and converted into an electric signal. At this time, if the target position required for random access is input from the outside, this target position is stored, the pickup is then moved to the target position, and the target position and the movement point where the target position is recorded are recorded. Compare and confirm. In this case, if the target position does not coincide with the movement point, the pickup is moved by a required distance to gradually reduce the difference from the target position. In order to track the recording pit, the pickup is servoed in both the track and focus directions.When moving the pickup, first turn off the servo loop in the track direction and then move the pickup. The moving position is stored, the tracking servo is turned on, and the number of rotations of the CD is controlled. In this state, the procedure for determining the difference in distance between the DC and the stored target position is repeated.

In this way, the random access technique for moving the pickup to the target position is a basic technique that is the center of each function of the CD player such as the beginning of a song, repeated playing, and pause.

[0006]

However, in the conventional random access, the linear velocity is set to a constant value in advance and a plurality of moving positions are used to reach the target position. In particular, the linear velocity of a commercially available CD is 1 .2 to 1.4 m / s, and there is a problem that the moving position passing through the CD changes at these various linear velocities and the random access time also increases accordingly. For this reason, it is possible to perform control in which calculation is performed in consideration of different linear velocities for each CD, or different passing times per track at different inner and outer peripheral portions, but the control scale for that purpose becomes too large. Another problem arises.

Therefore, in view of the above problems, it is an object of the present invention to provide an access device for a compact disc player, which can shorten random access while making the scale suitable for CDs having various constant linear velocities.

[0008]

In order to solve the above problems, the present invention provides a random access device of a compact disc player for randomly accessing tracks of a compact disc having a constant linear velocity by a jump track number deriving means, Address error deriving means and jump track number correcting means are provided.

The jump track number deriving means derives the jump track number from the current address of the pickup to the target address of the tracks of the compact disk from the relationship between the pickup position and the address at a reference constant linear velocity. The address error deriving unit jumps by the number of tracks obtained by the jump track number deriving unit, and then derives an address error between the target address and the jumped address.

When the address error obtained by the address difference deriving means is larger than a predetermined value, the jump track number correcting means corrects the jump track number according to the magnitude of the address error.

[0011]

According to the random access device for the compact disc player of the present invention, the jump track number deriving means determines the number of jump tracks from the present address of the pickup of the compact disc to the target address by a constant reference line. The address error between the target address and the address after the jump is derived from the relationship between the pickup position and the address at high speed, and after the address error deriving unit jumps by the number of tracks obtained by the jump track number deriving unit. When the address error derived and obtained by the address difference deriving unit by the jump track number correcting unit is larger than a predetermined value, the jump track number is corrected according to the magnitude of the address error.
Therefore, when performing random access, even if the CDs have different constant linear velocities, it is possible to always perform an appropriate jump without increasing the size of the device, and shorten the time required for random access.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a random access device of a compact disc player according to an embodiment of the present invention.
The compact disc player shown in the figure includes a CD 1 storing music information and the like, a pickup 3 for extracting information from the CD 1, a disc motor 4 for rotating the CD 1 at a constant linear velocity, and a pickup servo for driving the pickup 3. A circuit 5, a disk motor drive circuit 6 for driving the disk motor 4, and a signal for converting a signal from the pickup 3 into a music signal and creating data for controlling the pickup and outputting the data to the pickup servo circuit 5 and further a CD It includes a pickup data processing device 7 for forming data for making the linear velocity constant and outputting it to the disk motor drive circuit 6. Note that, for example, the focus servo and the like are not directly related to the present invention, and thus the description thereof will be omitted.

FIG. 2 is a diagram showing the structure of data stored in the CD. As shown in the figure, one frame consists of a synchronization signal, a control signal, and a music signal, and 75 frames consist of one.
Equivalent to seconds. This synchronization signal is extracted and output to the disk motor drive circuit 6 to be used for constant linear velocity control of the disk motor 4. The music signal is processed by a signal processing device (not shown) to form a reproduced sound.

The control signal includes a music head signal, a music number, a phrase, a continuous time (performance time), an elapsed time and the like. The continuous time of this control signal is given as a XX minute XX second XX frame, which will be used in the following description as an address of the frame. The relationship between the continuous time address, the radius of the CD, and the linear velocity will be described. FIG. 3 is a diagram showing the relationship between the pickup position and the through time (performance time). The horizontal axis of this figure represents the CD radius (the number of tracks), and the left vertical axis represents the CD passing time (computation time). The relationship between the CD radius and the passing time and the radius is when the linear velocity of the CD is high. If the radius is the same, the threading time becomes short, and conversely, if the CD linear velocity is low, the threading time becomes long. This is because the passing time difference per 100 tracks represented by the right vertical axis becomes smaller when the linear velocity is higher with respect to the radius of the CD.

FIG. 4 is a diagram showing a configuration for correcting a random access track jump in the pickup data processing device, and FIGS. 5 and 6 are views (Nos. 1 and 2) showing a flowchart for correcting a random access track jump. is there. As shown in FIG. 5, in the pickup data processing device 7, in step 1, when starting by turning on the power, initialization for main servo control is performed.

In step 2, it is judged whether or not there is a request for a trunk jump by random access by key input. In step 3, if there is no trunk jump in the above step, main processing such as tracking servo and focus servo is performed. In step 4, the above process is repeated unless the usage request is exhausted due to power failure or the like. Next, a case where there is a track jump request in step 2 will be described.

The random access track jump correction device shown in FIG. 4 includes jump track number deriving means 71 for deriving the number of jump tracks from the current access to the target address. Jump track number deriving means 71
The operation will be described with reference to FIG. In step 11 of FIG. 6, the current adrace TA is stored from the control signal from the pickup 3.

In step 12, the jump destination address TB given by the key input is stored. In step 13, a certain linear velocity, for example, a linear velocity of 1.3 m / s
From the pickup position and address in Fig. 3,
For example, assuming that the track positions corresponding to the addresses TA and TB are NA and NB, the number N of tracks to be jumped is derived as follows.

N = NB-NA In step 14, the tracking servo is turned off. In step 15, the sled carrying the entire pickup is moved by the number of jump tracks. Since the movement of the sled is suitable for a large movement, it is used for coarse adjustment, and is used in combination with fine adjustment for moving only the objective lens described later.

Next, the random access track jump correction apparatus shown in FIG. 4 includes an address error deriving means 72 for deriving an error between the target address and the jumped address. The operation of the address error deriving means 72 will be described with reference to FIG. In step 16 of FIG. 6, the tracking servo is turned on. In step 17, the current address Tc after the jump is extracted from the control signal from the pickup and stored. And the target address T
The difference ΔT between B and the address TC after the jump is calculated as follows.

ΔT = TC-TB Next, the random access track jump correction device shown in FIG. 4 includes a jump track number correction means 73 for correcting the jump track number N obtained in the step. The operation of the jump track number correcting means 73 will be described with reference to FIG. In steps 18 and 19 of FIG. 6, it is determined whether ΔT is within the following range.

-To <ΔT <To Here, To may be set to, for example, about 10% of the jump destination address TB stored in step 12. If the above inequalities are not satisfied in steps 20 and 21, the following correction count is formed and the number N of jump tracks in step 13 is corrected as follows.

If To ≤ ΔT, that is, if the same jump distance is set and the value of the linear velocity is small and the target address is jumped, the correction is made as N1 = N × (1-ao). Where ao = (TC-TA) / (TC-
TB) When ΔT≤-To, that is, when the same jump distance is set and the linear velocity value is large and the target address is jumped, the correction is made as N1 = N × (1 + ao). In step 22, it is determined whether the following formula is satisfied.

| ΔT | ≦ To For example, in the case of a linear velocity of 1.3 m / s, this is the transit time for moving several tens of tracks on average. When the above formula is not satisfied, the process returns to step 11 and the above process is repeated. When the above expression is satisfied, the objective lens is moved. As a result, the speed of movement becomes smaller than that of the sled, so that the number of times the pickup crosses the track can be counted by counting pulsed pulses such as tracking errors, so that the target address can be reached.

[0025]

As described above, according to the present invention, the error between the jump address and the target address is calculated based on the relationship between the pickup position and the through time with respect to the constant constant linear velocity as the reference, and the next jump track number. Since the correction is made to the above, even when the CD is a constant linear velocity which is different when random access is performed, it is possible to always perform an appropriate jump without increasing the scale of the device, and shorten the time required for access.

[Brief description of drawings]

FIG. 1 is a diagram showing a random access device of a compact disc player according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of data stored in a CD.

FIG. 3 is a diagram showing a relationship between a pickup position and a through time (performance time).

FIG. 4 is a diagram showing a configuration for correcting a track jump of a random accelerator in a pickup data processing device.

FIG. 5 is a diagram showing a flowchart for correcting a random access track jump (No. 1).

FIG. 6 is a diagram showing a flowchart for correcting a random access track jump (No. 2).

FIG. 7 is a diagram illustrating random access of a conventional CD.

[Explanation of symbols]

 1 ... Compact disc 2 ... Track 3 ... Pickup 4 ... Disc motor 5 ... Pickup servo circuit 6 ... Disc motor drive circuit 7 ... Pickup data processing device 71 ... Jump track number deriving means 72 ... Address difference deriving means 73 ... Jump track number correction means

Claims (1)

[Claims] 1. A random access device of a compact disc player for randomly accessing a track of a compact disc (1) having a constant linear velocity by a pickup (3), wherein the pickup (3) of the track of the compact disc (1). The jump track number deriving means (71) for deriving the jump track number from the current address to the target address from the relationship between the pickup position and the address at the reference constant linear velocity, and the jump track number deriving means (71). An address error deriving means (72) for deriving an address error between the target address and the jumped address after jumping by the obtained number of tracks; and the address error obtained by the address difference deriving means (72). Is larger than a predetermined value, the address A random access device for a compact disc player, comprising: jump track number correcting means (73) for correcting the jump track number according to the magnitude of the track error.