JP2580147B2 - Off-track control method in disk playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a range of addresses to be allowed depending on the frequency of the off-track, when a so-called jump of the track occurs due to an external vibration or the like in reproducing a disc. The present invention relates to an off-track control method in a disk reproducing apparatus in which is made variable.

[Conventional technology and its problems]

In a reproducing apparatus for an optical disk, for example, a compact disk, the subcode recorded on the disk is always read and the current address is stored, while the next address to be read, that is, the address to be originally reproduced (expected address) Is determined that normal reproduction is being performed. Therefore, if a track deviates due to external vibration or the like, a large difference occurs between the current address and the expected address. When this difference occurs, the pickup is controlled to return to the expected address.

For example, in the above-described disk reproducing apparatus, if the difference between the expected address and the current address is 1 second or more, it is determined that the track is out of track and the returning operation is performed. When the vehicle is traveling on a gravel road or the like, the off-track becomes large and frequently occurs. Therefore, if the difference between the expected address and the current address is about 1 second, the above-mentioned return operation is rather troublesome. In other words, there is a problem that the music is hardly progressed during the occurrence of the vibration, and the sound is muted during the return operation, so that the silent time becomes longer.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has a method of controlling a track off-track in a disk reproducing apparatus in which the allowable range of the return operation is increased as the track off-track becomes more frequent so that a small track off is not detected. The purpose is to provide.

[Summary of the Invention]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention aims to prevent a small off-track from being detected and change an allowable range of a return operation as the frequency of occurrence of off-track due to external vibration or the like increases.

(Example of the invention)

Next, a case in which one embodiment of the present invention is applied to a disk reproducing apparatus that selects one disk from a magazine containing a large number of disks, pulls out the disk, and reproduces the selected disk will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a magazine for sequentially storing N (N is a natural number of 2 or more) disks at a predetermined pitch. The magazine 1 is provided with N trays for holding disks, which protrude from the magazine body and are housed therein. The magazine 1 is detachably mounted on a predetermined mounting portion. One of the N disks D _{1 to} D _N stored on the N trays as a plurality of disk storage positions provided in the magazine 1 is rotated by a disk take-out / transport mechanism 2 by a rotating shaft of a spindle motor 3. It is conveyed onto the disk carrying surface of the turntable 4 fixed to and clamped. The disc take-out / transport mechanism 2 includes a projecting member for projecting the tray of the magazine 1 to move the disc onto the disc carrying surface of the turntable 4, and the projecting member moving the disc onto the disc carrying surface of the turntable 4. It has a clamp mechanism for clamping the disc, a moving plate for changing the relative position of the projecting member with respect to the magazine 1 in the tray arrangement direction, and a sensor for detecting the position of the moving plate, the operation of the clamp mechanism, and the like. ing. The position of the protruding member is changed by moving the moving plate in the disk take-out / transport mechanism 2, so that the disk can be selected. The configurations of the magazine 1 and the disc take-out / transport mechanism 2 are described in detail in Japanese Patent Application No. 60-153651.

The information recorded on the disk Dn that has been taken out of the magazine 1 by the disk take-out / transport mechanism 2 and clamped on the disk carrying surface of the turntable 4 is read by the optical pickup 6. The pickup 6 contains a laser diode, an objective lens, a focus actuator, a tracking actuator, a photodetector, and the like. The output of the pickup 6 is supplied to each of a focus servo circuit 7, a tracking servo circuit 8, and a reproduction clock generation circuit 9 including an RF amplifier.

In the focus servo circuit 7, a focus error signal is generated by, for example, an astigmatism method, and a focus actuator in the pickup 6 is driven according to the error signal. As a result, the laser light emitted from the laser diode and having passed through the objective lens is focused on the recording surface of the disk Dn to form an information detection light spot. In the tracking servo circuit 8, a tracking error signal is generated by, for example, a push-pull method, and the error signal is sent to the tracking actuator in the pickup 6 and the carriage servo circuit 10. The output of the carriage servo circuit 10 is supplied to a motor Ma for driving a carriage (not shown) carrying the pickup 6, and the pickup 6 is sent in the radial direction of the disk Dn.

A reproduction clock signal for demodulation is generated in the reproduction clock generation circuit 9 and supplied to the spindle servo circuit 11. In the spindle servo circuit 11, a drive signal corresponding to the phase difference between the reproduction clock and the reference clock from the clock generation circuit 12 is generated, the spindle motor 3 is driven, and control is performed so that the track linear velocity of the disk Dn becomes constant. Is done. The output of the RF amplifier in the reproduction clock generation circuit 9 is supplied to the EFM demodulation circuit 13 including the frame synchronization circuit together with the reproduction clock. The demodulated output of the EFM demodulation circuit 13 is used for deinterleaving of the demodulated data signal, error detection,
The data is processed by a data processing circuit 14 that performs correction, correction, and the like.
Thereafter, the demodulated output is temporarily stored in the data memory 15, read out by the clock signal from the clock generation circuit 12, and converted into an analog signal by the D / A (digital / analog) converter 16. This analog signal is output as a left and right audio signal via an LPF (low-pass filter) 17 and an amplifier 18. The amplifier 18 is configured such that the frequency characteristic changes according to the control data supplied thereto.

On the other hand, the control signal in the data from the EFM demodulation circuit 13 is supplied to the system controller 20, and various information such as the middle of a song, the interval between songs, the song number, the playing time, and the model number of the disc are read. This system controller
20 is processor, ROM (read only memory), RAM
(Ramdom access memory), interface circuit,
It is formed of one or more microcomputers including a timer and the like. This system controller 20
, The processor operates in accordance with a program stored in the ROM in advance and based on the flowchart of FIG.
Various detection signals from the disc take-out / transport mechanism 2, the operation unit 21
, And supplies various commands and data to the carriage servo circuit 10, the spindle servo circuit 11, the amplifier 18, the display 22, and the drive circuits 24 and 25 by processing the key input data from the CPU and the output data of the random number generation circuit 23. The random number generating circuit 23 is configured, for example, to latch the output of an m (m is a natural number) base counter whose coefficient value sequentially changes in a very short cycle in response to a data output command, and then output the latched value. The drive circuits 24 and 25 are configured to supply a drive current according to a command to the motors Mb and Mc that drive the moving plate and the protruding member in the disk take-out and transport mechanism 2, respectively.

Reference numeral 26 denotes a RAM for storing information from the system controller 20.

S ₁ to S ₄ is in the various detection switches disposed in the vicinity of the magazine 1 which is attached to a predetermined attachment portion, a magazine detection switch for transmitting the output S ₁ is the magazine 1 is mounted on a predetermined mounting portion, S ₂ moves up and down the disk detection switch, S ₃ is tray detecting switch, S ₄ turntable 4 for detecting whether the tray is housed in the magazine 1 for detecting the disc presence of within the projected tray This is a magazine position detection switch for detecting the position of the magazine 1.

Next, the operation of the processor in the system controller 20 will be described with reference to the flowchart of FIG.

First, when turning on the power, the magazine 1 is whether the processor monitors set at a predetermined mounting portion (step a), a magazine detection switch S ₁ the magazine 1 is mounted on a predetermined mounting portion detects a set of the magazine 1 When the detection signal is sent to the processor, the processor determines that the magazine 1 has been set and proceeds to the next step. In addition, the operation is stopped when not mounted.

In the next step, the magazine 1 is moved up and down to set the magazine 1 at a position where the uppermost or lowermost tray can be pulled out (step b). When the magazine position detecting switch S ₄ sends out a position signal of the magazine 1 to the processor, the processor proceeds to the next step.

In the next step, it is detected whether included in the tray in the disk to be drawn (step c), when the disc detecting switch S ₂ detects the disc proceeds next step. Then, in the next step, the processor monitors whether the reproduction switch has been turned on (step d),
Here, when the ON of the reproduction switch is not detected, the operation of the reproduction switch is awaited. When the reproduction switch is operated and turned on, the processor outputs a signal for loading the disc to the reproduction apparatus. Accordingly, the playback device loads the disc (step e), rotates the disc, and the pickup starts reading the disc to enter the playback state (step f).

In step g, the count value of the counter A for determining the protection range is reset to 0, and the process proceeds to step h to read the current address from the subcode.

In step i, it is determined which one of steps j, r, and s is to be performed based on the count value of the counter A.

That is, if the count value A of the counter A is 0, it is determined that the process proceeds to step j, if A is 1, the process proceeds to step r, and if A is m, the process proceeds to step s.

In steps j, r, and s, the difference between the current address read in step h and the expected address read immediately before there is no off-track is determined. In step j, | expected address−current address | <1 In step r, it is determined whether or not | expected address−current address | <2. In step s, it is determined whether or not | expected address−current address | <m + 1. If the determination is YES, The process proceeds to step k, and in the case of NO, that is, when it is determined that the track is off, the process proceeds to step n.

In Step n, it is determined whether or not the count value A of the counter A is equal to m. If the determination is YES, the process proceeds to Step p.

In step o, the count value of the counter A is incremented by one,
The process proceeds to step p to start the off-track returning operation to return the track.

At step q, the count value B of the time counter B is set to n, and the process proceeds to step m to update the expected address, and then proceeds to step h.

If it is determined in Steps j, r and s that the track is not out of track, the process proceeds to Step k, in which the count of the counter B is decremented by 1 at regular intervals, and the result of the subtraction is 0.
Is determined, that is, whether n seconds have elapsed,
When the determination is YES, the process proceeds to step l, and when the determination is NO, the process proceeds to step m.

In Step l, it is determined whether or not the count value A of the counter A is 0, and if the determination is YES, the process proceeds to Step m.
If NO, the process proceeds to step t, decrements the count value of the counter A by 1, and sets n to the counter B, and proceeds to step m.

That is, when a track deviates for n seconds counted by the counter B, the allowable range represented by | expected address−current address | is increased each time deviation occurs.

If no off-track occurs in n seconds, the allowable range represented by | expected address−current address | is reduced every n seconds.

〔The invention's effect〕

According to the present invention, as described above, according to the frequency of off-track due to external vibration or the like, for example, when it frequently occurs, small off-track is not detected and the allowable range of the return operation is changed, so that external vibration is reduced. This solves the various problems that occur when performing a return operation every time the track goes off the track when it is severe, thereby providing a disk reproducing apparatus that does not cause discomfort to the listener.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a disk reproducing apparatus used in the present invention, and FIG. 2 is a flowchart according to the present invention. 1 ... magazine, 2 ... disc take-out and transfer mechanism, 20 ...
System controller, S ₁ … Magazine detection switch, S ₂ … Disk detection switch, S ₃ … Tray storage detection switch, S ₄ … Magazine position detection switch.

Claims (1)

(57) [Claims] In a disk reproducing apparatus having a function of returning to a predetermined address when an off-track occurs due to an external vibration or the like, reading is performed to judge that an off-track has occurred according to the frequency of occurrence of an off-track. An off-track control method in a disk reproducing apparatus, wherein an allowable range of a difference between a current address and an expected address read immediately before no off-track is varied.