JPH0337861A - Disk discriminating method - Google Patents

Abstract

PURPOSE:To discriminate plural kinds of disks with different diameters by reading index information recorded on the disk, detecting all the reproducing time of the disk, and comparing them with a prescribed threshold value. CONSTITUTION:When the disk 3 is loaded with a desired loading mechanism, the focusing search of a beam is performed on a loaded disk 3, and furthermore, it is discriminated whether or not the focusing search is completed. Next, a spindle motor 1 is started up, and the reading of the index information with the disk 3 is performed. At this time, the gain of a motor driver circuit 9 is set at the gain of the disk with the diameter of 8cm. Read index information is stored in a RAM in a microcomputer 8. Next, it is discriminated whether or not all reproducing time stored in the RAM is less than a threshold value. And the disk to be reproduced is discriminated as the one with diameter of 8cm if a result shows YES, and it is discriminated as the one with diameter of 12cm if the result shows NO.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a disk discrimination method for discriminating several types of disks based on their diameters.

(Existing technology) Some existing compact disc players are capable of playing both 12 cm diameter discs and g cm diameter discs. In these disc players, the rotation of the disc is controlled at a constant linear velocity to play the disc. When reading recorded information, it is necessary to change the gain of the servo circuit that drives the disc rotation motor or the application time of the braking pulse that brakes the disc depending on the type of disc being played. This is because the weights of the 8 cm diameter disc and the 12 cm diameter disc are different, and therefore the rotational moment of each disc is different.

As a method for detecting the size of a disk, for example, Japanese Utility Model Application Publication No. 59-149261 (GIIBl 9/l 2
), there is one in which a detection element is arranged on a tray for transporting a disk. However, in this case, since the detection element is provided separately, the number of parts increases and the cost increases, and the detection element and the main body circuit must be electrically connected, making the structure complicated.

(c) Problems to be Solved by the Invention Therefore, the present invention aims to provide a disc discrimination method that can accurately discriminate the disc size even if a separate detection element or the like is provided.

(d) Means for Solving the Problems In view of the above problems, the disc discrimination method of the present invention includes the steps of reading table of contents information recorded on the disc to detect the total playback time of the disc, and determining the total playback time by a predetermined time. The first feature is that the method includes a step of comparing with a threshold value.

It also includes a step of detecting the time required from the start of the disc until it reaches a predetermined rotational state, a step of comparing this time with a predetermined threshold, and a step of detecting the total playback time of the disc from the table of contents information of the disc. , the second feature is that the method includes the step of comparing the total playback time with a predetermined threshold value, and the step of determining the size of the disc based on the two detection outputs (() obtained from the two comparison steps). do.

(e) Effect Generally, the total reproduction time of information recorded on a small diameter disk is shorter than the total reproduction time of a large diameter disk. The first feature of the present invention focuses on this point, and by detecting the total playback time from the table of contents information of the disc and comparing this total playback time with a predetermined threshold, the size of the disc to be played is determined. Determine the

Furthermore, the second feature improves the disc discrimination accuracy by adding a further step to the first feature. Since the moment of inertia of the disk differs depending on its size, the time required from startup until the linear velocity becomes constant varies. A further step of the second feature focuses on this point, and compares the time from the start of the disk until the linear velocity becomes constant with a predetermined threshold, and adjusts the size of the disk according to the result of this comparison. Determine the The second feature determines the size of the disk based on the result of this determination and the result of the first feature.

(F) EXAMPLE An example of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a player that can play two types of compact discs, one with a diameter of 8 cm and one with a diameter of 12 cm.

FIG. 1 is a circuit block diagram of an embodiment. In the figure,
(1) is a spindle motor, (2) is a turntable that is pivotally attached to the rotating shaft of spindle motor (1), (3) is a disk supported by turntable (2), (・1)
is the pickup, (5) is the RF amplifier that amplifies the signal from the big knob (・1), and (6) is the pickup (4).
), (7) is a focus tracking servo circuit that performs focus and tracking control, (7) is a digital signal processing circuit, (8) is a microcomputer, (9)
) is a motor driver circuit that controls the rotation of the spindle motor (1), and (10) is a gain switching circuit that switches the gain of the motor driver circuit (9).

In this embodiment, table of contents information (T
, O, C: Table of Contents), the total playback time (Ta) of the disc included in the threshold (Ts
= 23 minutes), the disc to be played is an 8 cffl diameter disc depending on whether Ta≦23 minutes, but it is 12 minutes.
It is determined whether the disc has a cm diameter.

Here, the threshold value Ts is set to 23 minutes based on the following basis.

FIG. 2 shows the configuration of a 3 cm diameter compact disc defined by the standard. Data is recorded in a program area, and the number of trunks that can exist in this program area is as follows, assuming a track pitch of 1.5 μm. Since the total track length in the program area is the total number of tracks multiplied by the average length of one track, we get: Therefore, the linear velocity of the disk is 1,2 m/s
Then, the total playback time will be.

Next, the disc discrimination and reproduction operation of this embodiment (this operation is controlled by the microcomputer (8)) will be explained based on the flowchart of FIG.

When a disc is loaded by a desired loading mechanism (step 1), a focus search of the beam is performed on the loaded disc in step 2, and a check is made as to whether or not the focus search is completed in step 3. It is determined. When the disk is properly focused in step 3, the spindle motor is started in step 4, and the T, O, and C information of the disk is read in step 5. Incidentally, the gain of the motor driver circuit in the operation of step 4 or step 5 is set to the gain of the 8cffI diameter disk. The T, O, C information read in step 5 is sent to the microcomputer (8) in step 6.
Random ACcess Mem
ory).

Next, in step 7, it is determined whether the total playback time Ta stored in the RAM is less than or equal to the threshold value Ts.

If the determination in step 7 is YES, it is determined that the disc to be played is an 8 cm diameter disc, and therefore the gain of the motor driver circuit (9) is maintained at the gain for an 8 am diameter disc (step 8 ). If the determination in step 7 is No, it is determined that the disc to be played is a 12 cm diameter disc, and therefore the gain of the motor driver circuit (9) is changed to the 12 cm diameter disc via the gain switching circuit (10). The display is switched to a large disk drive (step 9). As described above, a gain corresponding to the disc to be played is set in the motor driver circuit (9), and the player enters a playback standby state.

FIG. 4 is a flowchart of a disc stop operation for stopping a disc in a playback state. When the user performs a stop operation on the player, in step 1,
It is determined whether the total playback time Ta of the TOC information stored in the RAM is less than or equal to a threshold value Ts. If YES is determined in step 1, the disc being played is a gem.
It is determined that the disk has a diameter of 8 in step 2.
The braking time for cm diameter discs is set.

If the determination in step I is No, it is determined that the disc being played is a 12 cm diameter disc, and in step 3 a large disc craking time for a 12 cm diameter disc is set.

Here, each braking time is calculated based on both the number of rotations of the disc and the size of the disc. That is, since the disk is rotated at a constant linear velocity, the rotational speed of the disk is faster when the inner circumference of the disk is being reproduced than when the outer circumference of the disk is being reproduced. Therefore, even if the disc is the same, the braking time (the application time of the reverse rotation driving voltage applied to the motor) differs depending on the playback position of the disc. Further, since the rotation moment of the disk differs depending on its size, even if a reverse rotation drive voltage is applied to the motor for the same braking time, the degree of deceleration will differ.

In consideration of this point, in steps 2 and 3, the braking time is calculated and set according to the playback position of the disc and the size of the disc.

When the braking time is set in this way, the braking time is executed in step 4, and the braking time is executed in step 5.
When the elapse of the set braking time is detected, the braking operation is stopped.

In the above embodiment, it is possible to perform size discrimination with good accuracy for most discs, but there are rare cases where a large disc with a diameter of 12 cm has a total playback time of 23 minutes or less.
Therefore, if such a disk is used in the above embodiment, the disk size will be incorrectly determined. The following embodiment solves this inconvenience by adding another disk discrimination step in addition to the discrimination step of the above embodiment, and discriminates the disk size based on the discrimination results of both steps. . Below is a fifth example of such an example.
This will be explained using the flowchart shown in the figure.

When it is determined in step 2 whether a disk is mounted, the spindle motor is accelerated by a constant driving force in step 2. When 150m5 is measured after starting the spindle motor in step 3, next step 4
At this point, the CLV servo is turned on. Then, in step 5, it is determined whether the linear velocity of the disk has been locked to the specified value, and if NO here, in step 6, the
It is determined whether 420 m5 has elapsed since the LV servo was turned on. If the determination in step 6 is NO, the process returns to step 5 and repeats the same loop.

In steps 5 and 6, the disk CLV servo is set to T.
In this step, it is determined whether the disc to be played is a 3 cm diameter disc or not based on whether or not the disc is locked within s = 420 ms. If the disc to be played is a 3c+n diameter disc, the rotational acceleration is greater than that of a 12cm diameter disc, so the CLV servo locks that much faster. Ts = 420ms, 8cm diameter disk is CL
When the servo lock is achieved earlier than Ts at the threshold value of the lock time when V servo is applied, that is, if the determination result in step 5 is YES, the 8 cm diameter disc discrimination flag is set to 1 in step 7. is set to

If the motor servo is not locked within Ts', the 8 cm diameter disk discrimination flag is set to O in step 8. However, in this case, even if the motor servo is not locked within Ts', the reproduced disc cannot be immediately determined to be a 12 cm diameter disc. This is because even if the playback disc is an 8cm diameter disc, due to disturbances in the servo system (for example, if the servo is controlled based on the detection timing of the synchronization signal recorded on the disc, the synchronization signal may be missing). This is because the servo lock time may exceed 420 m5.

When the flag for identifying an 8cm diameter disc is set in the above steps, the total playback time Ta in the T, O, and C information is detected in step 9, and furthermore, the total playback time Ta is set at the threshold g.
A determination is made in step 10 as to whether or not it is greater than or equal to lTs. If the determination in step 10 is YES, step 1
1, the flag for determining the 12c+n diameter disk is set to 1, and if the determination is No, the flag for determining the 12c'm diameter is set to 0.

When the 8 am rough flag and the 12 cm diameter flag are set in this manner, it is then determined whether the reproduced disc has a diameter of 3 cm or 12 cm, according to the flowchart of FIG. If it is determined in step 1 that the disc has a diameter of 8 cm, it is determined in step 3 that the playback disc has a diameter of 8 cm. If No in step 1, the playback disc has a diameter of 8 cm or 12 cm, but then in step 2 it is determined whether the 12 cm diameter flag is 1, and if YES here, In step 1, it is determined that the reproduced disc is a 12 cm diameter disc.

The determination in step 2 is based on the determination in step 1 that the playback disc is probably a 12 cm diameter disc.
This is to determine the elimination method in a state where there is a possibility that it is a 3c+n diameter disc, and if No in step 2, it is determined that the disc is not a 12cm diameter disc and is a 3c+n diameter disc.

As described above, according to this embodiment, the disc size is determined based on the 2ffi determination results of determining the disc size based on the CLV servo lock time of the disc and determining the disc size based on the total playback time of the disc. It is possible to determine the disk size more accurately than in the first embodiment.

In the second embodiment, the order of the step of determining the disk size based on the CLV servo lock time and the step 7 of determining the disk size based on the total playback time of the disk may be reversed. Furthermore, although the above embodiments are both related to disk discrimination for CLV-controlled disks, it goes without saying that the present invention can also be applied to CAV-controlled disks.

(G) Effects of the Invention As described above, according to the present invention, it is possible to accurately determine the disk size without providing a separate detection element, and it is possible to reduce the cost and simplify the H4 formation compared to the conventional example. I can do it.

[Brief explanation of drawings]

The figures all relate to embodiments of the present invention; Fig. 1 is a circuit block diagram thereof, Fig. 2 is a groove diagram of an 8 cm diameter compact disc, and Figs. 3 and 4 are flow charts of the first embodiment. , FIG. 5, and FIG. 6 are flowcharts of the second embodiment. (3)...Disk, (8)...Microcomputer.

Claims (2)

[Claims] (1) A disc discrimination method for discriminating several types of discs with different diameters, which includes the steps of reading table of contents information recorded on the disc to detect the total playback time of the disc, and setting this total playback time to a predetermined threshold. A method for determining a disc, comprising the steps of: (2) A disk discrimination method for discriminating between several types of disks with different diameters, which includes the steps of detecting the time required from disk startup to reaching a predetermined rotational state, and comparing this time with a predetermined threshold value. a step of detecting the total playback time of the disc from the table of contents information of the disc;
A method for discriminating a disc, comprising the steps of: comparing the total playback time with a predetermined threshold; and determining the size of the disc based on two detection outputs obtained from the two comparison steps.