DIATONE DP-105

Commentary

A CD player with technologies such as 3-beam laser pickups and servo circuit LSIs.

Equipped with Diatone's original 3-beam system laser pickup.
In this method, the laser light emitted from a semiconductor laser is first divided by a grating plate into a light for reading signals and a left and right laser light for tracking servo. The left and right reflected lights have the same output, but if there is even a slight difference between them, there will be a difference in brightness between the two.
This allows us to catch tracking errors and control the signal detection beam so that it always follows each pit line.

It is equipped with a focus servo that optically detects the coupling state on the photodiode by the combination of a converging lens and a cylindrical lens.
In this servo circuit, if the image of the laser beam connected to the photodiode is a true circle, the focus is judged to be normal, and if it is an ellipse, it is judged to be a focus error. Based on this, the up-and-down motion of the rotating disk is detected, and the pickup is controlled so that the signal detection laser beam from the objective lens reaches an accurate end point on the disk.

It adopts a unique tracking mechanism using a rotary mirror.
In addition, the use of special rubber material eliminates vibration noise during high-speed search.

In order to obtain sufficient resolution and aberration, the objective lens is mounted with a machining accuracy of less than 1 / 2 of the laser wavelength. In response to the focus error signal from the servo circuit, the objective lens is moved at high speed by the change of magnetic flux density.
In addition, the suspension has been removed in order to eliminate resonance noise during driving.

We have developed and installed special LSIs for servo circuits such as tracking servo, focus servo and pickup feed servo.
A one chip microcomputer is used for the circuit that processes the sequence control commands.

The D/A converter is equipped with an integrating D/A converter with 16-bit accuracy.
The analog filter after D/A conversion uses a Chebyshev type low-pass filter with a unique circuit configuration.

No lead wires are used in the signal circuit from the D/A converter to the line output terminal. Moreover, the output terminal is directly mounted on the printed circuit board. This reduces signal transmission loss and eliminates degradation of high frequency characteristics and noise generation.
The printed circuit board has been designed with an optimum pattern to improve channel separation.

An independent DC stabilizing power supply circuit is installed in the analog amplifier section to prevent noise generated from the digital system and servo circuit from adversely affecting the analog circuit.

It is equipped with a random program of up to 30 songs, a cue in the index display and a 4-mode repeat function.

Model Rating

Type	CD Player
Number of channels	2-channel stereo
Frequency characteristic	5 Hz to 20000 Hz
Dynamic range	94 dB or more
Channel separation	90 dB or more
Distortion factor	0.003% or Less (1 kHz, 0 dB)
Wow flutter	Quartz accuracy (below measurement limit)
Power consumption	18W
External dimensions	Width 424x Height 79x Depth 300 mm
Weight	5.3kg