JPH01204229A - Servo control method in optical disk player - Google Patents

Abstract

PURPOSE:To shorten starting time by revolving a spindle motor at speed lower than in the normal condition in advance of the starting time, accelerating the spindle motor when a focus servo goes to the normal condition, and transferring the spindle motor to the normal condition. CONSTITUTION:A servo circuit 20 is provided and a servo controller 21, etc., is equipped to supply a control signal to the servo circuit 20 and to control the each operation of a spindle motor 2, an optical pack-up 3 and a sending mechanism 4. At the activating time, before the focus servo of the optical pick-up 3 is started, the spindle motor 2 is revolved at the speed lower than the normal condition in advance. Then, when the focus servo goes to the normal condition, the spindle motor 2 is accelerated and transferred to the normal condition. Thus, even when a compact motor, whose activating torque is comparatively small, is used, the activating time until all servos go to the normal condition can be shortened.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an optical disc player such as a CD (compact disc) player, and in particular, the invention relates to an optical disc player such as a CD (compact disc) player, and in particular, the operation of the spindle motor and optical pickup until the operation reaches a steady state. The present invention relates to a servo control method for an optical disc player that aims to shorten startup time.

"Prior Art" FIG. 3 is a block diagram showing the configuration of a conventional CD player. In this figure, 1 is a CD, 2 is a spindle motor that rotationally drives the CDI, 3 is an optical pickup that reads digital information recorded by pits on the CDl, and 4 is a feeder that moves the pickup 3 in the direction of half of the CDI. It is a mechanism. The pickup 3 is composed of a semiconductor laser, an objective lens, an optical sensor, a focus adjustment mechanism, etc. The read signal output from the pickup 3 is amplified by an nF amplifier 5, and then processed by a signal processing circuit 6. Processing such as demodulation, code error correction, and b17 correction is performed, and the signal is converted into an analog audio signal by a D/A (digital/analog) converter 7. Further, this audio signal is subjected to processing such as amplification in an audio circuit 8, and then outputted to an external speaker or the like via an output terminal 9.

Further, 10 is a servo circuit, which performs constant linear velocity control (CLV servo) of the spindle motor 2 and focus adjustment control (focus servo) of the pickup 3 based on a control signal supplied from a servo controller II to be described later.
, controls the feeding operation of the feeding mechanism 4 (thread servo). In this case, the servo circuit 10 is a spindle driver composed of an OP amplifier (operational amplifier) 14 and resistors R, ,R,! 5, a drive current is supplied to the spindle motor 2, thereby controlling the rotation of the spindle motor 2. 11 is a servo controller that controls each operation of the spindle motor 2, optical pickup 3, and feed mechanism 4 via the servo circuit 10;
U (Central Processing Unit), ROM (Read Only Memory) that stores the programs used by this CPU, RAM (Random Access Memory) that temporarily stores various data, and exchanges data with the outside ■10 ( It consists of an input/output) boat. This servo controller
! The RF amplifier 5 supplies information regarding the number of tracks moved by the pickup 3, and the signal processing circuit 6 supplies absolute time information (regarding the elapsed time from the start point where the first song begins) read from each part of the CDI. information) is now provided. ! 2 is the servo controller! An operating section 13 is a display device that provides various displays based on display commands supplied from the servo controller 11.

When the play button of the operation section 12 is pressed, the servo controller 11 starts each section according to the operating procedure shown in FIG. 4.

■Time t when the play button is pressed. At this point, the power of the servo circuit IO is turned on.

■The time T required for the operation of the peripheral circuits to stabilize has elapsed 1. , drive the focus adjuster (1) in the pickup 3, and adjust the objective lens to C.
Start a focus search (-) to move away from the DI pit surface.

(2) Thereafter, at time t when time T2 has elapsed, a focus search (+) is started to bring the objective lens closer to the CDI pit surface.

■Then, at time t, when time T3 has elapsed and the objective lens has passed the focused point, the focus servo is turned on, and at the same time, the spindle motor 2 is started, and the CD
Start rotating drive I.

■After starting the spindle motor 2, time T4 has elapsed and C
Time t4 when the LV servo is turned on and shifts to steady state
Turn on tracking servo and thread servo.

As a result of the above, all the servos are in a steady state, but the elapsed time after the play button is pressed, that is, the startup time is the time T,+T+T3+T4.

"Problems to be Solved by the Invention" By the way, in the conventional CD player described above, the spindle motor 2 is not activated at time t0 when the play button is pressed, and at time t when the focus servo is turned on, The spindle motor 2 was started for the first time. Therefore, as the startup time until all servos reach steady state, time T I + 'l' t
+ T s + T 4 is required, and as a result, there is a problem in that it takes a long time until music or the like is actually played back.

In this case, the time T4 from when the spindle motor 2 is started until it reaches the specified rotation speed and the CLV servo is turned on depends largely on the starting torque of the spindle motor 2. The start-up time can be shortened by using a (DC) motor or a DC brushless motor using rare earth magnets. However, when a small and inexpensive ordinary brushed DC motor is used, a large starting torque cannot be obtained, and it has been difficult to shorten the starting time.

This invention was made in view of the above-mentioned circumstances, and provides a servo circuit for an optical disc player that can shorten the time required for starting even when a small and inexpensive motor with a relatively low starting torque is used. is intended to provide.

"Means for Solving the Problems" The present invention provides a servo control method for controlling the operation of a spindle motor and an optical pickup of an optical disc player, which includes: at startup, before starting focus servo of the optical pickup; The spindle motor is rotated in advance at a speed slower than a steady state, and when the focus servo reaches a steady state, the spindle motor is accelerated;
It is characterized by a transition to a steady state.

"Operation" According to the above method, at startup, the spindle motor is rotating at a speed slower than the steady state in advance, and when the focus servo reaches the steady state, the spindle motor is accelerated and shifts to the steady state. Therefore, even when a small and inexpensive motor with a relatively low starting torque is used, the starting time until all servos are in a steady state is shortened.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a CD player according to an embodiment of the present invention. In this diagram, parts corresponding to those in FIG. .

In FIG. 1, 20 is a servo circuit, 21 supplies a control signal to the servo circuit 20, and the spindle motor 2,
A servo controller that controls each operation of the optical pickup 3 and the feed mechanism 4, T" is a servo circuit 2
The transistor rtb, which is turned on/off by 0, is the spindle driver when the transistor Tr is turned on. This is a bias addition resistor that supplies a bias current to the inverting input terminal of the OP amplifier 14 constituting the OP amplifier 5.

Like the servo controller 11 shown in FIG. 3, the servo controller 21 includes a CPU, a ROM, and an IIA
When the play button on the operation section 12 is pressed, each section is activated according to the operating procedure shown in FIG.

■Time t when the play button is pressed. At this point, the power of the servo circuit 20 is turned on. At the same time, the transistor Tr is turned on and the OP is connected via the bias addition resistor Rb.
Amplifier! A bias current is supplied to the inverting input terminal of 4, thereby causing the spindle motor 2 to rotate at a slower speed than in the steady state.

■After that, at time t, when the time T necessary for the operation of the peripheral circuit to stabilize has elapsed, a focus search (-) is started to move the objective lens of the optical pickup 3 away from the pit surface of the CDI. .

(2) At time t, when time T has elapsed after the start of this focus search (-), a focus search (+) is started to bring the objective lens closer to the pit surface of the CDI.

■ After the start of this focus search (+), time T3 has elapsed, and at time t3 when the objective lens passes through the focused point, the focus servo is turned on, and at the same time, the transistor Tr is turned off, and this time , a drive current is supplied to the spindle motor 2 via the spindle driver 1.5, thereby accelerating the spindle motor 2.

■After the spindle motor 2 starts accelerating, the specified rotational speed is reached after time a...T4', and at time t,' when the CLV servo is turned on and the steady state is reached, the tracking servo and thread servo Turn on.

As a result of the above, all servos are in a steady state, and the startup time in this case is T + + 'r t + T s +
It becomes T a'. Here, at time t3 when the focus servo is turned on, the spindle motor 2 has already been activated.
Since the spindle motor 2 is rotating at a slower speed than in the steady state, the time T4' required for the spindle motor 2 to shift to the steady state from this point t4 is shorter than the conventionally required time 'r4 (Fig. 4). It's over. Therefore, the startup time in this embodiment (T I+ 'r !+ T s+ 'r
4') is the conventional startup time (T r + T t+
T3+T4), the time corresponding to the difference between time T4 and T4' is reduced.

Note that the rotation start timing of the spindle motor 2 mentioned above is the time t when the power of the servo circuit 20 is turned on. It does not have to be at the same time as, in short, it can be done at any time before the time t3 when the focus servo is turned on. Further, in addition to the circuit using the bias addition resistor Rb, a drive current from a system other than the servo circuit 20 may be supplied to the spindle motor 2 to perform the same operation.

Furthermore, in the above-mentioned embodiment, the case where it is applied to a normal CD player for playing music has been described.
CD-ROM, CD-1 (compact disc interactive media), CD-V (compact disc
It goes without saying that the present invention may be applied to various optical disc players that handle discs/videos), LDs (laser discs), and the like.

"Effects of the Invention" As explained above, according to the present invention, at startup, the spindle motor is rotated in advance at a speed slower than the steady state, and when the focus servo reaches the steady state, the spindle motor is accelerated. However, since it is made to shift to a steady state, the starting time until all servos reach a steady state can be shortened even when a small and inexpensive C motor with a relatively small starting torque is used as a spindle motor. This has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a CD player to which a servo control method according to an embodiment of the present invention is applied, FIG. 2 is a diagram for explaining the operation timing at startup of the embodiment, and FIG. The figure is a block diagram showing the configuration of a conventional CD player, and FIG. 4 is a diagram for explaining the operation timing when starting up the CD player. ! ...CD, 2...Spindle motor, 3...Optical pickup, 4...
...Feeding mechanism, 14...OP amplifier, 15
...Spindle driver, rtb...
Bias addition resistor, 20... Servo circuit, 21
... Servo controller.

Claims (1)

[Claims] In a servo control method for controlling the operation of a spindle motor and an optical pickup of an optical disc player, the spindle motor is brought into a steady state in advance before starting focus servo of the optical pickup at startup. A servo control method for an optical disc player, characterized in that the spindle motor is rotated at a slower speed than the focus servo, and when the focus servo reaches a steady state, the spindle motor is accelerated to shift to a steady state.