JPH02108275A - Disk player - Google Patents

Abstract

PURPOSE:To realize the stable control in order to make a linear velocity of the rotation constant independently of a disk shape by making variable an allowable frequency band and/or a gain of a motor control means according to the disk shape. CONSTITUTION:When the disk is 12cm, prescribed reflected light is detected by a pickup 1 with laser light in its convergence, and an H-level signal is outputted from a level detector 11. In the case of an 8cm disk, because of no prescribed reflected light, an L-level signal is outputted from the detector 11. Whether it is the 8cm disk or 12cm disk is decided by a control circuit 19 in accordance with an output of this level detector 11. Then, when it is the 12cm disk, an FET 15F is turned off and an FET 66F is turned on by the control circuit 19, and when it is the 8cm disk, the FET 15F is on and the FET 66F is off. In the case of the 8cm disk, the cutoff frequency of a low pass filter 66 of a demodulation clock generating circuit 6 is raised, while the gain of a motor driving circuit 15 is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a disc player that can play discs of different shapes.

(0) Conventional Technology In order to read data signals accurately in a so-called digital audio disk, it is necessary to control the disk motor so that the linear velocity of the disk is kept accurately constant.

For this reason, a disc player generally includes a clock signal generation circuit that generates a clock signal based on a data signal detected from a disc, and a clock signal generation circuit, as disclosed in, for example, Japanese Patent Laid-Open No. 159682/1982. A comparison circuit that compares the phases of the output of the circuit and the output of the reference oscillator, and a motor drive circuit that drives and controls the motor using the output of the comparison circuit are provided.

(...) Problems to be Solved by the Invention Incidentally, in addition to the 12 cm disk, a so-called gem disk has recently been released, and the outer circumferential diameters of these disks are 12 cm and 8 cm, respectively, depending on the amount of information.

The above-mentioned disc player generally adjusts the permissible frequency band of the PLL section of the clock signal generation circuit and/or the gain of the motor drive circuit so that the rotation speed becomes stable quickly for a 12 cm disc. Therefore, when playing an 8cm disc with this disc player, the 3cm
Due to the difference in weight between the disc and the 12 cm disc, the load on the motor is reduced, and the motor attempts to rotate at a higher speed than when playing a 12 cm disc. At this time, the frequency band of the input signal to the clock signal generation circuit exceeds the allowable frequency band of this clock signal generation circuit, so
There was a risk that the PLL section would no longer be able to lock the disk, causing the disk to rotate out of control.

(d) Means for Solving the Problems The disc player of the present invention has a disc shape determining means for determining the shape of a disc, a data detecting means for detecting a data signal from the disc, and a standard 5! a motor control means for controlling a disk motor so that the rotation of the disk is at a constant linear velocity based on the outputs of the vibrator, the data detection means, and the reference oscillator; control means for varying the allowable frequency band and/or gain of the

(0 effect) The present invention is constructed as described above, and the permissible frequency band and/or gain of the motor control means is varied depending on the shape of the disk.

(F) Embodiment An embodiment of the present invention will be described based on the drawings. In Figure 1, (+) is a pick amplifier that emits a laser beam to the disk (2) and reproduces the information recorded on the disk (2), and the data signal (SO) detected by this pickup (1) are the amplifier circuit (3) and the waveform shaping circuit (4)
The signal is supplied to a demodulation circuit (5) and a demodulated black/red signal generation circuit (6) via the demodulation circuit (5). Demodulated black signal generation circuit (
6), the demodulation clock frequency (
4,3218MH2) signal (Sl), and the generated pulse output is supplied to the demodulation circuit (5), so that the demodulation circuit (5) generates the data signal (Sl) based on the demodulation clock signal (51). Detect the length of SO),
Outputs binary data according to the length of the data signal. The data signal (So) detected by the pickup (1) has a reference frequency (4,3218MHz) depending on the signal level.
The length of the data signal (SO) is defined as 3 to 11 bits, and the length of the data signal (SO) is determined from the demodulation circuit (5).
That is, binary data corresponding to the signal level is output.

(7) is a D/A conversion circuit that converts the binary digital data from the demodulation circuit (5) into an analog signal, and the analog signal is amplified by an amplifier (not shown) and then reproduced by a speaker. (8) is a 7-occasion servo circuit, which keeps the χ of the pitch 1 block circuit (1) always on the information recording jib surface of the disk by controlling the distance between the object lens and the disk (2). Accurately converge laser light. (9) is a feed servo circuit that connects the pickup (1) to the disk (
2) controls the feed motor (10) that moves in the radial direction; (11) is a level detector that detects whether the output level of the amplifier (3) is equal to or higher than a predetermined value. (1
2) is the output of a reference oscillator (13) composed of a crystal oscillator that oscillates a reference oscillation frequency of 1.3218 MHz;
A phase comparator circuit that manually inputs the output of the demodulated clock signal generation circuit (6) outputs an error signal P according to the phase difference between the two inputs.
WM Output. (14) (14) is a low-pass filter that generates all the DC voltage according to the error signal from the phase comparison circuit (12), (15) 41M3e low-pass filter (14), the output of (14) is used to control the disc (2). A motor drive circuit that drives a rotating spindle motor (16), which includes an operational amplifier (15A) and resistors (15B) and (15C) connected to the non-inverting and inverting inputs of the operational amplifier.
! :,;IIT column-connected FL feedback resistor (15D)
, (15E) and FET (15F) connected in series to one feedback resistor (15E), FET
The gain changes due to ON-OFF of (15F). (17) is an inside switch that detects whether or not the pickup (1) is located at the bk inner circumference of the disk (2). (18) is a PLAY key, and (19) is a control circuit consisting of a microcomputer, which controls the focus servo circuit (
8), FET of the feed servo circuit (9), demodulation clock signal generation circuit (6) and motor drive circuit (15)
(15F).

Figure 2 shows the demodulated clock signal generator circuit (
6), in which (61) is the pickup (1)
(62) is a one-shot multivibrator that operates at the rising edge of the data signal (SO) detected by t, (63)
are each one-shot multivibrator (6I), (
(62) is an OR gate which inputs the output of the OR gate, (64) is a phase comparison circuit which inputs the output of the OR gate and the output of a voltage controlled oscillator (65) which is oscillating a frequency close to the reference frequency. It is a low pass filter.

The phase comparison circuit (64) includes a 5AND gate (64A
), AND gate (64B), and inverter (64C
), P channel FET (64D), N channel FET (64E), resistor (64F),
It consists of a capacitor (64G). The low-pass filter (66) also includes an operational amplifier (66A), feedback resistors (66Fl), (66C), capacitors (66D), (66E), and one capacitor (66E).
) is connected in parallel with the F E T (66F) and controlled by the control circuit (19), and this F E
By turning off T (66F), the cutoff frequency increases.

In the configuration described above, when the data signal (SO) is detected by the pickup (1), the demodulated clock signal generation circuit (6) outputs a signal that is activated at the rising edge of the data signal (SO). The output (S2) of the shot multivibrator (61) and the free-running oscillating voltage controlled oscillator (65)
The outputs (Sl) of are compared in phase by a phase comparison circuit (64). At this time, as shown in FIG.
In , the output (S2) of the one-shot multivibrator (61) and the output (St) of the voltage controlled oscillator (65)
A match is detected by the NAND gate (64A), during which the capacitor (64G) is charged by conduction of the p-channel FET (64D). However, when the AND gate (64B) subsequently detects a match between the output (S2) of the one-shot multi-by-break (61) and the inverter output (64C) of the voltage controlled oscillator (65), the λ channel F E T (64E ) conduction causes capacitor (6
4G) is discharged. Therefore, if the phases match, the discharging and charging periods will be the same, and as a result, the potential of the capacitor (64G) will not change.

However, when the phase shifts by one, a difference occurs between the charging and discharging periods, which causes a change in the potential of the capacitor (64G), and a voltage corresponding to the difference potential passes through the low-pass filter (66) to the voltage controlled oscillator ( 65), the voltage side 91! is supplied to the voltage side 91! so that the phase difference becomes zero! The frequency of the oscillator (65) is controlled. Also, one-shot multi-bye break (6
2) output (S3) and the output of voltage controlled oscillation B (65) (
The voltage controlled oscillation frequency and the data signal (So) are phase-matched.

In this way, a demodulated clock signal synchronized with the data signal is obtained from the demodulated clock signal generation circuit (6). If the rotation speed of the spindle motor (16) is not normal, the length of the data signal (SO) will deviate.
The frequency of the demodulated clock signal will deviate from the frequency of the reference oscillation B (13), and the phase comparator circuit (12), low-pass filter (14) (14), motor drive circuit (14)
5) to match the spindle motor (1).
6), that is, the linear velocity of the disk (2) is controlled to be constant.

FIG. 4 shows a flowchart of the main part of the program written in the control circuit (19), and the operation will be explained below based on this. First, when the P LAY key (]8) is operated, a command signal is output to the feed servo circuit (9) to position the pickup (1) at a position 5 cm away from the center of the disc (2). , based on the travel time of the pickup (1) (determine the 7th position) (steps S-1, 2).

In this state, a focus search command signal is output to the focus servo circuit (8) in step 5-
3) Level detection! Monitor the output from (11).

At this time, if there is a disc, that is, if it is a 12 cm disc, a predetermined reflected light will be detected by the re-pickup (1) due to the convergence of the laser beam, and level detection 5 (11
) outputs an H level signal. If it is a 3cm disc, there is no predetermined reflected light, so level detection 1
5(ll) outputs an L level signal. Therefore,
The control circuit (19) determines whether it is an 8cnn disc or a 12cm disc based on the output of the level detector (11). Then, the m1I91] circuit (19) is
If you have a 12cm disc, turn FET (15F) OFF and FET (66F) ON; if you have an 8cm disc, set FET (15F) to QN, FET
(66F) (steps S-1, 5, 9)
). As a result, in the case of an 8cm disk, the cutoff frequency of the low-pass filter (66) of the demodulation clock generation circuit (6) can be made higher than in the case of a 12cm disk, and the gain of the motor drive 1J circuit (15) can be lowered. be able to. Therefore, each disk can be made to reach a stable rotational speed quickly. Then, in the case of a 12cm disk, the control circuit (19) outputs a command signal to the spindle motor (16) to start rotating, and also outputs a command signal to the feed servo circuit (9) to switch the pink-up (1) from the inside switch. Output a command signal to the position where (■7) is turned ON, and then
7) is turned ON, a transition is made to the PLAY state (steps S-6 to S-14). Also, in the case of a 3cm disc,
A command signal is output to the feed servo circuit (9) so that the pickup (1) is in the position where the insight switch (17) is turned on, and the inside switch (17) is set to the Q position.
When it reaches N, a focus search command signal is outputted to the focus servo circuit (8) again.

7 When the orcus search is completed, the spindle motor (1
6) Output a command signal to start rotation, and PLAY
It will be in a LAY state (steps 5-10 to 14)
.

In addition, in the above configuration, the demodulated clock signal generation circuit (6
), phase comparison circuit (12), low-pass filter (14)
(14) and the motor drive circuit (15) constitute a motor control means.

Further, the present invention provides the cut-off frequency of the low-pass filter (66) of the demodulated clock signal generation circuit (6) and the motor drive circuit (
Although both of the gains in step 15) are made variable, it is also possible to make the demodulation clock signal generation circuit (6) long by making only one of them variable.

(() Effects of the Invention The present invention changes the permissible frequency band and/or gain of the motor control means according to the shape of the disk as shown in L. However, the rotation of the disk can be stably controlled to maintain a constant linear velocity.

[Brief explanation of the drawing]

Figure 1 is a professional diagram of the disc player of this book, Figure 2 is a block diagram of the demodulated clock signal generation circuit,
3 is an output waveform diagram of the main part of FIG. 2, and FIG. 4 is a flowchart showing the program of the main part of the control circuit. (])...Pick amplifier, (6)...Demodulated clock signal generation circuit, (8)...7 One-of-a-kind servo circuit, (9
)...Feed servo circuit, (12)...Phase comparison circuit, (13)...Reference oscillator, (14)(+4)...
・Low pass filter, (]5)...Motor drive circuit,
(16)...Spindle motor. Applicant Sanyo Electric Co., Ltd. and one other agent Patent attorney Nishino! A Tsugu (1 other person) Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A disk shape determining means for determining the shape of the disk, a data detecting means for detecting data signals from the disk, a reference oscillator, and the rotation of the disk is maintained at a constant linear velocity based on the outputs of the data detecting means and the reference oscillator. A disk characterized in that it is comprised of a motor control means for controlling a motor of the disk so that player.