JPH0617215Y2 - CD player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a CD player, and more particularly to a CD player which detects a disk size and switches the servo constant of a disk motor accordingly.

[Prior Art] Conventionally, by discriminating the size of the disk by mechanical means,
A disk motor, that is, a servo constant of a rotary servo system is known.

[Problems to be solved by the device]

However, in the conventional CD player, since the means for detecting the disc size is mechanical, the number of parts is increased and the mechanism is complicated, resulting in a problem of high cost.

Therefore, a main object of the present invention is to provide a CD player which is inexpensive and can discriminate the disc size and switch the servo constants accordingly.

[Means for Solving the Problems]

This invention is a CD player including a discriminating means for discriminating a disc size attached to a CD player and a means for switching a servo constant of a servo system of the disc motor in response to an output of the discriminating means. The CD player is characterized in that the disc size is discriminated based on the time difference between the activation and the reading of the Q code.

[Action]

When the disc is set in the CD player, the system control microcomputer outputs a start pulse to start the disc motor. Then, after the disk motor is activated, the time until the Q code is first read by the system control microcomputer is measured. And
For example, if the disk size is 8 cm, its weight is small, so given a constant activation pulse,
The disk motor starts up at a relatively high speed. On the other hand, 1
If it is 2 cm, its weight is so large that the disk motor starts up at a relatively low speed when a constant starting pulse is given. Therefore, there is a difference according to the disk size in the time until the Q code is input after startup. By utilizing this time difference, the disc size can be determined.

[Effect of device]

According to this invention, since it is not necessary to use a conventional mechanical means for disc size determination, the cost does not increase and an inexpensive CD player can be obtained.

〔Example〕

Referring to FIG. 2, the CD player 10 of this embodiment includes a rotary servo system 12. The rotary servo system 12 includes a disc motor 14, and a compact disc (hereinafter, “CD”) 16 of 8 cm disc or 12 cm disc is attached to a spindle of the disc motor 14.

The pickup 18 is arranged facing the signal surface of the CD 16, the signal is read from the signal surface of the CD 16, and the reproduction signal is output from the pickup 18. Then, the reproduction signal from the pickup 18 is amplified by the preamplifier 20, and then supplied to the synchronization signal detector 22 and the data processor 34.

The sync signal detector 22 extracts the sync signal included in the reproduction signal and supplies it to the phase comparator 24. A reference oscillator 26 including, for example, a crystal oscillator is connected to the phase comparator 24, and a phase difference signal corresponding to the phase difference between the reference signal from the reference oscillator 26 and the synchronization signal is output from the phase comparator 24. The FV converter 28 converts the applied phase difference signal into a corresponding voltage signal. The voltage signal from the FV converter 28 is passed through the amplifier 30 to the driver 3
Given to 2. The driver 32 drives the disk motor 14 by the applied drive voltage. Since such a rotary servo system 12 is already well known, further description is omitted here.

The data processor 34 described above converts the reproduction signal into reproduction data, and the reproduction data is given to the system control microcomputer 36. System control microcomputer 36
Outputs a signal when the sub code included in the reproduction data, for example, the Q code is read, and supplies the signal to the transistor 38.

When the CD 16 is set in the CD player 10, the system control microcomputer 36 turns on the activation pulse in step S1 shown in FIG. Accordingly driver 3
A drive voltage is applied to 2 and the disk motor 14 is started. At this time, the system control microcomputer 36 starts an 8 cm / 12 cm timer formed in an appropriate area of a RAM (not shown) at the same time when the activation pulse is turned on.

Then, in step S3, the system control microcomputer 36 reads the Q code of the reproduction data from the data processor 34. In step S5, it is determined whether the time (T) from the output of the starting pulse to the first reading of the Q code is longer than a reference value, for example, 820 msec. That is, since there is a weight difference between the 8 cm disc and the 12 cm disc, even if the same activation pulse is activated, the rotation speed is different and the Q code reading time (T) is also different. The system control microcomputer 36 uses this characteristic to determine the size of the CD 16. In step S5, if T ≦ 820 msec, it is determined as an 8 cm disc, and if T> 820 msec, it is determined as a 12 cm disc.

When it is determined that the 8 cm disc is attached, the process proceeds to step S7, and the system control microcomputer 36 outputs a signal "H" indicating the 8 cm disc. On the other hand, when it is determined that the disc is a 12 cm disc, the process proceeds to step S9, and "L" indicating a 12 cm disc is displayed.
The signal of is output.

As is clear from FIG. 3, when the output from the system control microcomputer 36 is "H", the two transistors 38a and 38b are turned on and the collector-
Since the emitters are conducting, the voltage signal from the FV converter 28, that is, the input voltage to the amplifier 30, is divided,
The input voltage to the operational amplifier 40 becomes small. On the other hand, when the output from the system control microcomputer 36 is "L", the transistors 38a and 38b are in the off state, so that the collector-emitter does not conduct, and the input voltage to the amplifier 30 is not affected and remains as it is. Operational amplifier 4
Input to 0.

In this way, the disc size is determined, and the optimum servo constants are automatically set for the 8 cm disc and the 12 cm disc, respectively.

When the CD 16 is replaced and the power of the CD player 10 is turned on / off, the output from the system control microcomputer 36 is set to always output "L" as an initial value. Even if it is set in the player 10, it reaches the predetermined number of rotations after the rotation is started.

As the servo constant switching means of the servo system of the disk motor 14, any suitable method other than the method of switching the input voltage of the amplifier 30 as in the embodiment can be used.

[Brief description of drawings]

FIG. 1 is a flow chart showing the operation of one embodiment of the present invention. FIG. 2 is a block diagram showing an embodiment of the present invention. FIG. 3 is a circuit diagram showing an example of the servo constant switching circuit. In the figure, 10 is a CD player, 12 is a rotary servo system, 14 is a disk motor, 16 is a CD, 34 is a data processor, 36 is a system control microcomputer, 3
Reference numerals 8, 38a and 38b denote transistors.

Claims (1)

[Scope of utility model registration request] 1. A CD player comprising a discriminating means mounted on a CD player for discriminating a disc size, and a means for switching a servo constant of a servo system of a disc motor in response to an output of the discriminating means. The CD player is characterized in that the disc size is discriminated based on a time difference between the activation of the disc motor and the reading of the Q code.