JP2005317134A - Disk reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively adjust data read out from a disk in accordance with the situation of a memory in which the data is stored temporarily. <P>SOLUTION: Adjustment items are determined in accordance with data quantity in the memory, a compression form, or combination of them, and adjustment is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a disc playback device such as an MD (mini disc) playback device, a CD (compact disc) playback device, or a DVD (Digital Versatile Disc) playback device, and refers to readjustment of control parameters of a servo circuit performed during playback. To do.

  In a disc playback device such as an MD playback device, a CD playback device, or a DVD playback device, data read from the disc at a speed faster than the playback speed is stored in the memory, and at the same time, data is read from the memory at the playback speed. The sound and video are reproduced after being read out. For this reason, even if reading of data from the disk is stopped for a certain period, reproduction can be continued using the data stored in the memory. Therefore, this period can be used to automatically adjust control parameters such as offset and gain of the servo circuit even during playback in order to correct variations in disk characteristics, aging of equipment, and changes due to temperature. it can.

  However, in the past, adjustment items were fixedly fixed, so if there are many adjustment items, if there is little data in the memory, re-adjustment will use up the data in the memory and cause sound interruptions. Cannot be readjusted. Conversely, if there are few adjustment items, effective adjustment cannot be performed.

Japanese Patent No. 3142497 (Japanese Patent Laid-Open No. 10-275344) JP-A-8-63863 JP-A-10-112124 JP 2001-34947 A JP-A-8-87753 JP-A-6-302104 JP-A-8-77577 JP-A-9-212882 JP 2000-57596 A

  Accordingly, an object of the present invention is to provide a disc reproducing apparatus capable of performing effective adjustment according to the memory condition.

  According to the present invention, when the adjustment of the servo control circuit is started at the time of reproducing the disk, the memory for temporarily storing the data read from the disk at the time of reproducing the disk is changed according to the state of the memory. There is provided a disk reproducing apparatus comprising adjustment item determining means for determining an adjustment item, and means for adjusting a servo control circuit for the determined adjustment item.

  FIG. 1 shows the configuration of an MD playback apparatus as an example of a disk playback apparatus to which the present invention is applied.

  As shown in FIG. 1, the MD reproducing apparatus is equipped with a spindle motor 3 for rotating a disk 2 stored in a cartridge 1, an objective lens 4 for reading data by irradiating the disk 2 with laser light, and an objective lens 4. An optical pickup 5 that focuses the beam on the signal surface of the disk 2 and tracks the track, and a thread feed motor 6 on which the entire optical pickup 5 including the objective lens 4 is placed are provided.

  The RF amplifier 7 generates and processes servo signals and audio signals necessary for determining the position of the laser spot from the signal from the optical pickup 5. The servo control circuit 8 receives a laser spot position signal from the RF amplifier 7 and performs focus servo control for controlling the optical pickup 5 so that the laser spot is correctly focused on the surface of the disk 2 or causes the track to be accurately tracked. Therefore, tracking servo control for controlling the optical pickup 5 is performed.

  The address decoder 9 demodulates the signal from the RF amplifier 7 to the address signal recorded in the pregroup of the disk 2, reads the absolute address, and controls the rotational speed of the disk 2 to keep the linear velocity of the reading unit constant. It works to take out the servo signal. An EFM (Eight Fourteen Modulation) and CIRC (Cross Interleaved Reed Solomon Code) decoder 10 receives signals from the address decoder 9 and the RF amplifier 7 and converts an 8-bit digital signal into a 14-bit recording format of the disc 2. Circuit (EFM) for performing error correction and circuit (CIRC) for performing signal processing for error correction. The anti-vibration memory controller 11 performs control to store data from the EFM and the CIRC decoder 10 in a semiconductor memory 12 constituted by a several Mbit DRAM (Dynamic Random Access Memory) and to output the stored data. Even if the optical pickup 5 flies due to vibration, sound skipping due to vibration is avoided by returning the optical pickup 5 to its original position while data is being reproduced on the semiconductor memory. The audio compression decoder 13 decodes the signal compressed on the disk 2 based on the auditory characteristics. The signal from the audio compression decoder 13 is converted from digital to analog by a D / A converter 14 (Digital to Analog Converter) and taken out as an audio output signal. The system controller 15 controls the servo control circuit 8, the EFM and CIRC decoder 10, and the anti-vibration memory controller 11, displays the control state on the display 16, and controls information such as on, off, and channel selection with the key 17. input. The thermistor 20 is provided to detect the temperature of the pickup 4 and its surroundings and readjust the servo circuit when a change in temperature is detected.

  FIG. 2 is a diagram for explaining the state of stored data stored in the semiconductor memory 12. As shown in the figure, in a stable state without shock (vibration), when data is fully stored in the memory 12 (for example, for 1 second), reading from the disk 2 is temporarily stopped, and the memory 12 When the accumulated data is reduced to a certain amount (for example, 5 seconds), reading of data from the disk 2 is started, and by repeating this operation, the data is always kept almost full in the memory 12. When the optical pickup 5 is removed from the track due to a shock, reading of data from the disk 2 is interrupted until the original position is found, so the amount of data in the memory 12 temporarily decreases.

  FIG. 3 is a diagram showing an outline of the tracking servo circuit and the focus servo circuit in the servo control circuit 8. As shown in FIG. 3, two amplifiers 81 for amplifying two signals from the photodetector of the optical pickup 5 and an amplifier 82 for taking the difference between the signals from the two amplifiers 81 as an error signal and amplifying the error signal. A switch 83 for permitting or prohibiting the output of the amplifier 82, and an actuator coil 84 for driving the optical pickup by an error signal. At the time of adjustment, the control unit 85 opens the switch 83, takes in the output signal of the amplifier 82, adjusts based on this output signal, and closes the switch 83 after adjustment.

  In order to adjust the gain, the output signal of the amplifier 82 is compared with the target value, and the amplification degree of the amplifier 82 is adjusted so that it becomes the target value.

  In order to adjust the offset, the emission of a laser (not shown) is stopped, and the gain of the amplifier 81 is adjusted so that the output of the amplifier 82 at this time becomes zero, or although not shown, the amplifier 82 is not shown. In the case of digital processing, the offset is adjusted by treating the output at this time as zero.

  Thus, the offset adjustment procedure includes a laser emission stop procedure and the like, and requires a relatively long time, but the frequency of the offset adjustment is low. On the other hand, gain adjustment is completed in a relatively short time, but the frequency at which adjustment is required is high.

  FIG. 4 is a flowchart showing a first example of automatic adjustment processing in the system controller 15. A data error or system error (such as servo failure) occurs during reproduction, or the temperature changes to a temperature detected by the thermistor 20. When there is, this automatic adjustment process is activated. First, the amount of data in the memory 12 is checked (step 1000). If it is 50% or more, adjustment is performed for all adjustment items (step 1002), and if it is 50% or less, some adjustment items are adjusted. Is performed (step 1004).

  All the adjustment items are, for example, adjustment of the focus system and tracking system offset, adjustment of the focus system gain, and adjustment of the tracking system gain. Some adjustment items are, for example, adjustment items excluding offset adjustment, which takes a relatively long time but requires a low frequency of adjustment.

  FIG. 5 is a flowchart of a second example of the automatic adjustment process. In MD, there are SP, LP2, and LP4 compression modes. With the same amount of data, LP2 can play back twice as long as SP, and LP4 can play back four times as long. Therefore, the compression mode of the disk is checked (step 1100). If LP4, all adjustment items are executed (step 1102), and if LP2, some adjustment items are executed (step 1104).

  FIG. 6 shows a third example of automatic adjustment. In this example, when the amount of data in the memory is 60% or more (step 1200), all adjustment items are executed (step 1202). When the amount of data is 50 to 60% (step 1204), the focus system and tracking are performed. System gain adjustment is performed (step 1206), and when 30 to 50% (step 1208), only tracking system gain adjustment is performed (step 1210), and when it is 30% or less, no adjustment is performed.

  FIG. 7 shows an example in which adjustment items are changed depending on the combination of the data amount and the compression format. When the compression format is LP4, all items are adjusted when the data amount is 50% or more, the gain adjustment of the focus system and tracking system is performed at 40 to 60%, and only the gain adjustment of the tracking system is performed at 40% or less. . On the other hand, when the compression format is LP2, all items are adjusted with a data amount of 80% or more.

  With the processing described above, it is possible to make effective adjustments according to the state of the memory without causing sound interruption. If there is no data in the memory at the start of readjustment, it is considered that sound interruption has already occurred. Therefore, the system can be restored to a good state as soon as possible by executing all the adjustment items. In addition, since the system may be out of control, all the adjustment items may be performed after the system is reset and initialized once.

It is a figure which shows the structure of MD reproducing | regenerating apparatus as an example of the disc reproducing | regenerating apparatus by which this invention is employ | adopted. It is a figure explaining the role of a memory. It is a figure which shows the structure of a servo control circuit. It is a flowchart which shows the 1st example of the automatic adjustment process of this invention. It is a flowchart which shows the 2nd example of the automatic adjustment process of this invention. It is a flowchart which shows the 3rd example of the automatic adjustment process of this invention. It is a flowchart which shows the 4th example of the automatic adjustment process of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cartridge 2 ... Disk 3 ... Spindle motor 4 ... Objective lens

Claims (6)

A memory for temporarily storing data read from the disc during playback of the disc;
An adjustment item determining means for determining an adjustment item according to the state of the memory when adjustment of the servo control circuit is started at the time of reproducing the disk;
And a means for adjusting the servo control circuit for the determined adjustment item.   2. The disk reproducing apparatus according to claim 1, wherein the adjustment item determining means determines the adjustment item according to the amount of data stored in the memory.   2. The disk reproducing apparatus according to claim 1, wherein the adjustment item determining means determines the adjustment item according to a compression format of data stored in the memory.   2. The disk reproducing apparatus according to claim 1, wherein the adjustment item determining means determines the adjustment item according to a combination of the amount of data stored in the memory and a compression format.   5. The disk reproducing apparatus according to claim 1, further comprising means for adjusting a servo control circuit for all adjustment items when the amount of data in the memory becomes zero during disk reproduction. .   6. The disk reproduction according to claim 5, further comprising means for initializing the system before adjusting the servo control circuit for all adjustment items when the amount of data in the memory becomes zero during disk reproduction. apparatus.

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