JP2000003514A - Pulse signal generation circuit for laser texture processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely perform a texture processing in a short time by using a high power laser beam. SOLUTION: This pulse signal generation circuit is provided with a detector 6 detecting an input laser beam, an integration circuit 7 integrating the output of the detector 6, a comparator 8 outputting a pulse width decision signal based on the output of the integration circuit 7 and a pulse generation circuit 3 outputting a pulse based on the pulse width decision signal, and is constituted so as to intensity-modulate the input laser beam by the output of the pulse generation circuit 3. That is, this circuit is constituted so as to perform the laser texture processing for a hard disk substrate surface after the laser energy is fixed by controlling pulse width for every one pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse signal generating circuit for laser texture processing, and more particularly to a pulse signal generating circuit for modulating a high-output laser whose output is unstable.

[0002]

2. Description of the Related Art Conventionally, the surface of a hard disk is subjected to texture processing in order to prevent attraction with a magnetic head. Laser processing is used to form minute projections with high accuracy by this texture processing. Such a laser processing method is described in, for example, Japanese Patent Application Laid-Open No. 9-19777.
The disclosure is disclosed in “Protrusion Forming Method” in Japanese Unexamined Patent Application Publication No. 2000-163,086.

In this projection forming method, a high-output laser such as a ruby laser is used. In particular,
As shown in FIG.
3 is excited, the rise of the voltage applied to the Q switch 15 is made gentle, and a long-time laser beam pulse suitable for forming minute projections on the surface of the flat plate is obtained. In FIG. 4, the semi-transparent mirror 16 and the Q switch 15 constitute a laser resonator in a pair.

[0004]

However, in the above-mentioned prior art, there is a problem that the shape of the minute projections formed varies because the laser oscillation is not stable because the Q value of the laser oscillation is low.

On the other hand, in the case of a gas laser or the like whose oscillation is stable, there is a problem that the laser energy is low and the texture processing takes a long time.

Accordingly, an object of the present invention is to perform texture processing with high accuracy in a short time by using high-power laser light regardless of pulse oscillation / continuous oscillation.

[0007]

According to the present invention, there is provided a laser texture for generating a modulation signal for laser texture processing for modulating a laser beam to form minute projections on a flat plate surface. A pulse signal generating circuit for processing, an integral comparator for photoelectrically converting a part of the laser light, time integrating the same, and outputting a pulse width determination signal based on a value of the time integration; A pulse generator for outputting a pulse based on a signal, wherein the pulse width is controlled for each pulse of the modulated laser light so that the laser light energy is equal for each pulse.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a pulse signal generating circuit for laser texture processing according to the present invention. As shown in FIG. 1, the pulse signal generating circuit for laser texture processing of the present invention photoelectrically converts a part of the laser light by the detector 6 and integrates the integrated light by the integrating circuit 7. Based on the value of the integration,
The apparatus includes an integration / comparing unit 10 that outputs a pulse width determination signal and a pulse generation unit 20 that outputs a pulse based on the pulse width determination signal.

The input of the pulse signal generating circuit for laser texture processing according to the present invention is a part of the laser beam for texture processing, which is input to the detector 6 to be photoelectrically converted, and this photoelectrically converted output is integrated. Thus, the laser beam intensity is monitored.

The output of the pulse signal generating circuit for laser texture processing according to the present invention is input to a laser modulator 30 where the intensity of the laser light is modulated. The intensity-modulated laser light passes through a focusing optical system 40. Thus, a minute spot is formed on the surface of the flat plate 50. Here, the flat plate 50 is rotated by a motor 60, and the surface of the flat plate 50 is textured by irradiating a minute laser beam spot for a predetermined time. In order to texture the entire surface of the flat plate 50, the focusing optical system 40 and the flat plate 50 may be relatively moved by moving means (not shown).

Hereinafter, each component of the pulse signal generating circuit for laser texture processing according to the present invention will be described.

The above-mentioned integration comparing section 10 includes a detector 6 such as a photodiode for photoelectrically converting a part of the laser beam, an integration circuit 7 for integrating the output of the detector 6, and an output of the integration circuit 7 having a predetermined setting. A comparator 8 for outputting a pulse width determination signal when the value becomes equal to the value.

The pulse generator 20 includes a pulse generator 2 for generating a pulse signal having a predetermined period, and a pulse generator 3 for resetting each pulse of the pulse signal with the pulse width determination signal.

Next, the operation of the pulse signal generating circuit for laser texture processing according to the present invention will be described with reference to FIG.

A pulse signal having a constant period is output from the pulse oscillator 2 and input to the pulse generation circuit 3.

The pulse generation circuit 3 triggers the integration circuit 7 at the rise of those pulses to start integration.

The output of the integrating circuit 7 is input to a comparator 8 and compared with a predetermined set value. Here, the predetermined set value is an integral level corresponding to a laser exposure amount optimal for texture processing, and is a value determined by a spot diameter of a laser beam, the number of rotations of a flat plate, a shape of a minute projection to be formed, a flat plate material, and the like. It is. Therefore, at time T1 when the integral value becomes equal to the set value, the microprojection having the optimal shape is formed on the flat plate.

Accordingly, the comparator 8 sends a pulse width determination signal to the pulse generation circuit 2 at time T1. Then, the pulse generation circuit 2 uses this pulse width determination signal as a reset signal to generate a pulse having a pulse width (T1-T0), and uses it as an input to the laser modulator 30.

The pulse width generated in this way is:
It fluctuates with the fluctuation of the detector output 6. Figure 2
In the example shown in (1), the pulse width (T1-T0) generated when the detector output is V1 is the pulse width (T3-T2) generated when the detector output is V2 (> V1). Greater than. Thus, even if the laser light intensity fluctuates, the laser light energy per pulse is kept constant.

By inputting such a modulation signal to a laser modulator 30 such as an electro-optic modulator or an acousto-optic modulator, the intensity of the incident laser light is modulated.

The laser texture processing of the hard disk can be performed by modulating the laser of the pulse mode output as described above. However, the laser light of the CW mode (continuous oscillation mode) such as an argon laser or an excimer laser is used for the laser texture processing. The light may be modulated in such a manner as to be pulsed and irradiated to the hard disk.

As described above, one embodiment of the present invention has been described with reference to FIGS. The present invention is not limited to the above embodiment, and a switch 9 may be provided between the detector 6 and the integrating circuit 7 as shown in FIG.

According to FIG. 3, the output (voltage or current) of the integrating circuit 7 is zero when the laser beam is not incident on the detector 6, but noise always occurs in the actual circuit. Since the noise component is also integrated in the integration circuit 7, especially when the width of the laser light pulse is shorter than the repetition period,
May not be ignored. In this case, by setting the switch 9 to the conductive state (ON) only while the pulse generation circuit 3 is outputting a signal, noise is not superimposed and the reliability of the circuit can be improved. This has the same effect even when the integration start time of the integration circuit 7 is set.

[0025]

According to the present invention described above, a stable hard disk can be texture-processed without depending on the stability of the original laser oscillator.

[Brief description of the drawings]

FIG. 1 is a block diagram of a laser pulse stabilizer according to the present invention.

FIG. 2 is a time chart for explaining the operation of the laser pulse stabilizing device of the present invention.

FIG. 3 is a block diagram of a laser pulse stabilizing device for reducing the influence of laser noise.

FIG. 4 shows a conventional projection forming method.

[Explanation of symbols]

 Reference Signs List 2 pulse oscillator 3 pulse width generation circuit 6 detector 7 integration circuit 8 comparator 9 switch 10 integration comparison section 20 pulse generation section 30 laser modulator 40 focusing optical system 50 flat plate 60 motor

Claims (3)

[Claims] 1. A laser texture processing pulse signal generating circuit for generating a laser texture processing modulation signal for modulating a laser light beam to form minute projections on a flat plate surface, wherein a part of the laser light And a pulse generation unit that outputs a pulse based on the pulse width determination signal, and an integration comparison unit that outputs a pulse width determination signal based on the value of the integration. Pulse signal generation circuit for laser texture processing. 2. An integration comparison unit comprising: a detector for photoelectrically converting a part of the laser light; an integration circuit for integrating an output of the detector; and an output of the integration circuit equal to a predetermined set value. A pulse generator for generating a pulse signal having a predetermined period, and a pulse for resetting each pulse of the pulse signal with the pulse width determination signal. The pulse signal generation circuit for laser texture processing according to claim 1, further comprising a generation circuit. 3. An integration comparator, comprising: a detector for photoelectrically converting a part of the laser light; an integration circuit for integrating an output of the detector; and an output of the integration circuit equal to a predetermined set value. 3. A pulse for laser texture processing according to claim 2, further comprising a comparison for outputting a pulse width determination signal when the detection is performed, and disconnecting the detector and the integration circuit until the integration is started. Signal generation circuit.