JPH03183064A - Stop controller for disk - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a disc stop control for stopping a disc rotated by a spindle motor in a disc player capable of playing discs such as compact discs (hereinafter referred to as CDs). It is related to the device.

[Conventional technology]

When reading information recorded on a disc such as a CD by scanning a reading beam along the track, the synchronization signal included in the recorded information and the reference synchronization signal are phase-compared and this phase difference is set to zero. A so-called spindle servo that rotates the disk is essential.

Information recorded on a CD is recorded at a constant linear velocity,
This linear velocity is 1.2 regardless of the inner or outer circumference of the disk.
It is defined in the range of m/s-1.4 m/s.

Furthermore, the recorded information is from 25mm to 58mm radius from the center of the disc.
Because the program area is recorded up to
rpm.

[Problem to be solved by the invention]

As mentioned above, in order to quickly bring a disk rotating at a relatively high rotational speed to a stop state, reverse rotational force (back electromotive force) is applied to the spindle motor that rotates the disk to stop it. Since the number of rotations differs depending on the position on the radius of the beam, if a constant reverse rotational force is applied for a certain period of time, there will be variations in the time it takes to stop.

In particular, if the time period during which this reverse rotational force is applied is short, the motor continues to rotate in a free run state. In the case of a player that clamps the disc in conjunction with the opening/closing operation of the lid, if the lid is forcibly opened manually, the rotating disc will suddenly be released from the clamping force and will fly out. It was a cause of injury.

Therefore, it may be possible to apply a sufficiently large reverse rotational force, but generally speaking, the driving force that drives the spindle motor is Pld
By changing the duty ratio of the M-modulated drive pulse,
Since that DC value is used, the saturation value level becomes the maximum reverse rotational force, and therefore it is not possible to apply a braking force that exceeds this level.

Furthermore, it is conceivable to monitor the rotation speed of the motor and accurately stop the motor. For example, if a motor is equipped with a rotation speed detection means such as a Hall element, the rotation speed per unit time (
In other words, if the rotational speed (rotational speed) decreases to a predetermined rotational speed, it may be possible to free-run the motor. However, in this case, it is necessary to provide a means such as a Hall element,
This results in an increase in the number of parts and an increase in cost.

[Means for solving gA problem]

The disk stop control device of the present invention is a disk stop control device in a playback device that reads information by rotating the disk at a predetermined linear velocity by a spindle motor, and the device is a disk stop control device for reading information by rotating the disk at a predetermined linear velocity by a spindle motor, and the device is a disk stop control device for reading information by rotating the disk at a predetermined linear velocity by a spindle motor, and the device is a disk stop control device for reading information by rotating the disk at a predetermined linear velocity by a spindle motor. The present invention is characterized by comprising a position detection means for determining position information on the disk radius where the reading point is located, and a control means for applying a predetermined reverse rotational force to the spindle motor for a predetermined period of time according to the position information.

[For production]

The disk stop control device configured as described above focuses on the fact that there is a correlation between the radial position of the reading beam during reproduction and the disk rotation speed, and uses the radial position information to determine the time to apply the reverse rotational force in advance. The rotating disk can be stopped quickly with a simple configuration.

〔Example〕

An embodiment of the disk stop control device of the present invention will be described below with reference to the drawings.

In FIG. 1, the pickup 2 is a disk (CD).
11 with a reading beam of laser light, the disc 1
The reproducing RF signal from the photodetector is amplified to a predetermined level by a reproducing amplifier 3 and then supplied to a waveform equalizing circuit 4. The waveform equalization circuit 4 shapes the waveform of the reproduced RF signal,
EFM (Eight to Fourteen Mod
(b) This is supplied to the signal processing circuit 5 and the synchronization signal extraction circuit 6 as a modulated pulse train signal.

The signal processing circuit 5 demodulates the EFM modulated signal, performs necessary processing such as error correction and deinterleaving, performs D/A conversion, and outputs audio signals of both L and R channels, and also outputs information. It demodulates the control data in the signal and outputs it to the control section 10, and is a well-known demodulating means for CD players. The synchronization signal extraction circuit 6 is E
The reproduced frame synchronization signal SY is extracted from the FM modulated pulse train signal, and this reproduced frame synchronization signal becomes the sole power of the CLV servo circuit 8. , CLV servo circuit 8 is supplied with a reference clock CK generated by clock generation circuit 7 as an external input, compared with reproduced frame synchronization signal SY, and this error component is supplied to motor drive circuit 9. The motor drive circuit 9 controls the rotational speed of the spindle motor 1 so that this error component becomes O.

Further, when a regeneration stop command is given by an external operation key, the control section 10 controls the motor drive circuit 9, turns off the servo, and forcibly applies reverse rotational force to the spindle motor 1.

Further, the data signal included in the reproduction information signal is demodulated by the signal processing circuit 5 and then supplied to the control section 10.

The control section 10 provides a command to stop the spindle motor to the motor drive circuit 9 in response to a command from an external operation key, and also has an arithmetic function as, for example, a microcomputer.

Next, the control data demodulated by the signal processing circuit 5 will be briefly explained.

In the CD recording format, control data of 14 channel bits (ie, 8 data bits) is recorded following a synchronization signal, and this control data has subcoding channels of P, Q, . . . , W. The format of channel Q, for example, among the sub-coding channels is shown in FIG.

In FIG. 2, data on channel Q consists of nine segments of 8 bits each.

The roles played by each segment are as follows.

TNR...Track number ~74) ZERO...All O AMIN...Absolute time (minutes) from the program area start position ASEC...Absolute time (seconds) from the program area start position AFRAME...Same as FRAME Not shown during playback In addition to displaying the song number, playback time, etc. from the information on the channel Q on the display section that does not display, these are also used as address information when searching for a desired program.

The present invention focuses on the fact that the absolute time from the program area start position, the position on the disk radius where the reading beam is located at that time, and the rotational angular velocity at that time have a correlation with each other.

Next, the operation of the present invention will be explained.

The control unit 10 reads from the output of the signal processing circuit 5 the absolute time and frame number from the program area start position at the time when a reproduction stop command is given by an external operation key. Assume that this information is M minutes, S seconds, and F frames. This number of frames takes a value from 0 to 74, so when counting the first frame as 1 frame, the absolute number of frames X is x = (MX60X75) + (SX75) + F + 1
+ + 6 (1). The relationship between this and absolute time t (see) is t = x / 75
...(2) becomes.

Also, when the inner diameter of the program area start position is a, the track pitch is b, and the number of tracks counted from the inner circumference is y, the total track length D is D = 27Ca + 2 π (
a+b)+27C(a+2b)+-+27C(a+(y
-1)b)=2π[(2/y)(2a+(y-1)b)
]...(3), and this is the total distance vt of the track played for t (seconds) at the linear velocity V, so t = (2π/v) (ay + b ((y-1) y/2))
...(4) Therefore πby2+π(2a-b)y-vt=0 ・
...(5). Solving equation (5) for y gives y = [π(b-2a)±(x 2(4a2-4ab+
b2)+4 πbvt) ' ]/2πb = (b-2a±(4a"-4ab+b" +4bv
t/π)')/2b・(6).

Since a, b, and v on the right side of equation (6) are each constant, it is understood that the number of tracks y from the innermost circumference can be determined by the time t obtained from the data of channel Q. However, among the signs in equation (6), a negative sign has no meaning, so this sign is assumed to be positive.

Next, the maximum value of y (that is, the number of tracks at the outermost circumference of the program area) is 25 mm at the innermost circumference and 5 mm at the outermost circumference.
8n+m and the track pitch is about 1.6μm, so (((58-25) X 1O-3)/(1,6X t
o-' )) + 1 = 20626.

Therefore, when the information reading point exists at the program area start position, if the time required to apply reverse rotation force to the motor until it stops is Z, and the stopping time at the program area end position is Zo, then at the current position track y, The time f(y) required to stop after applying reverse rotation force is f('t)'' (Z-Za) x (y/206
26)+Z, ...(7). 2 and 2° can be determined as constants through experiments, etc., and the control unit 10
controls the motor drive circuit 9 to apply reverse rotational force to the spindle motor for the f(y) time. In this way, the spindle motor is stopped accurately and quickly without being free-run or rotating in reverse.

Note that the example of the calculation process for f (y) described above is not limited to this. For example, as a method for calculating the number of tracks y, a correspondence table between absolute time and the number of tracks is prepared in the ROM and this is used. You may also refer to it.

If the above operation is represented in a flowchart, it will be as shown in FIG.

That is, first, the absolute time t of the subcode is read (
In step Sl), this absolute time is converted into an absolute number of frames X (S2). Furthermore, the number y of tracks from the innermost track is determined, and a function for the total number of tracks is calculated (S3, S4).

Then, the difference between the stopping times when the CD is at the highest rotational speed and the lowest rotational speed is multiplied by this function to calculate the reverse rotation time at the predetermined position (S5 and S6).

〔Effect of the invention〕

As described above, according to the disk stop control device of the present invention, at the time when a reproduction stop command is given, the time for applying a predetermined reverse rotation force is determined in advance according to the data read from the disk. Therefore, the spindle motor can be stopped reliably, and since a rotation speed detection device such as a Hall element is not required, costs can be reduced.

[Brief explanation of drawings]

Figure 1 shows a C to which the disk stop control device of the present invention is applied.
FIG. 2 is a block diagram showing the configuration of an embodiment of the D player, FIG. 2 is a diagram showing the data format of channel Q, and FIG. 3 is a flowchart explaining the operation of FIG. 1. l...Spindle motor 2...Pickup 3... 4...5...6...7...8...9...10...11...Reproduction amplifier, waveform equalization circuit, signal processing circuit, synchronization Signal extraction circuit, clock generation circuit, CLV servo circuit, motor drive circuit, control section, disk

Claims (1)

[Claims] A disk stop control device in a playback device that reads information by rotating the disk at a predetermined linear velocity with a spindle motor, wherein an information reading point scanned on the disk at the time of generation of a stop command is provided. A disk stop control device comprising: a position detecting means for obtaining position information on a radius of the disk; and a control means for applying a predetermined reverse rotational force to the spindle motor for a predetermined time according to the position information. .