It is CD player which supplied technology, such as 3 beam system laser pickup and LSI only for a servo circuit.
Three beam system
laser pickup original with a Diatone is carried.
By this system, the laser light first irradiated from the semiconductor
laser is divided into the light and the object for tracking servos which
read a signal with a grating plate by the laser light per right and left.
Although the catoptric light of each of these right and left is the same
output, even when it is small there, when gap arises, a difference appears
in the light and darkness of each catoptric light.
This catches a tracking error, and it is controlling so that a signal
detection beam always follows each pit sequence.
The focal servo which
detects optically the combined state on the photo-diode by the combination of a
収光 lens and a cylinder lens is carried.
A focus is normality if the image of
laser light tied on a photo-diode is a perfect circle form in this servo
circuit,It has distinguished that an ellipse form is a focal error, and the
shake of the upper and lower sides of the disc which rotates by this is
detected, and the pickup is controlled so that the signal detection laser light
from an objective lens connects an exact terminal point on a disc.
original tracking mechanism which uses a rotary mirror is adopted.
Furthermore, the oscillating sound at the time of a high-speed search is
removed by having adopted special rubber material.
In order to acquire
sufficient resolving power and aberration, what was finished with 1/2 or less
working accuracy of a laser light wavelength is carried in the objective lens, and the method of carrying out high-speed movement of the objective lens by
change of magnetic flux density is adopted as it to the focal error signal from
a servo circuit.
Moreover, the suspension is removed in order to eliminate
the vibration sound in the case of a drive.
LSI for exclusive use is
developed and carried in servo circuits, such as a tracking servo, a focal
servo, and a pickup sending servo.
Moreover, the one-chip microcomputer is
adopted as the circuit which processes a command of sequence control.
The found the integral type D/A converter of 16-bit accuracy is carried
in the D/A converter.
Moreover, the Chebychev type low pass filter with
original circuit composition is adopted as the analog filter after D/A
In the signal circuit from a D/A converter to a line-out
terminal, no lead is used, and also direct wearing of the output terminal is
carried out at the printed circuit board, and while reducing the transfer loss
of a signal, degradation of the high region characteristic and noise generating
Moreover, the optimal pattern design is carried out to the
printed circuit board, and the channel separation is improved.
direct-current regulated-power-supply circuit is established independently in
the analog amplifier part, and it has prevented the noise generated from a
digital system or a servo circuit having a bad influence on analog circuitry.
The random program of a maximum of 30 music, search by index display, 4
mode repeat function, etc. are carried.
|The number of channels
||5Hz - 20000Hz
||94dB or more
||90dB or more
||0.003% or less (1kHz, 0dB)
|Wow and flutter
||Quartz accuracy (below a measurement limit)
||Width 424x height 79x depth of 300mm