JPH02268258A - Hard-disk surface inspecting method - Google Patents

Abstract

PURPOSE:To perform accurate detection by comparing profile data based on the level change of reflected light with the data of non-defective part. CONSTITUTION:Strip shaped colored parts 2 and a defective part 3 are provided in a hard disk 1. An arranged data file has 64 arranged data in the radial direction R and 360 arranged data in the circumferential direction S. The data in the direction S are made to increment from 0 to 359, and the data in the direction R are made to increment from 0 to 63. The profile data Y in the direction R are obtained. The length, wherein the data other than 0 continue, and the number of the data are obtained. When both zeroth and 359th data in the direction S are not zero, it is regarded that one discolored part 2 is used, and the number is decreased by one. Thus the profile data for comparison are arranged. When the number of the continuing parts of the data which are not zero is not equal to the number of the discolored parts 2, it is judged that there is a defect. Thus, the quality can detected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a hard disk surface inspection method for inspecting the surface of a hard disk, particularly the presence or absence of defects on its outer periphery, by optical means.

(Prior Art) As a conventional hard disk surface inspection method, there is one that uses an inspection device as shown in FIG. 43 is a detection head, 44 is a signal processing device, 45 is a microcomputer, and 46 is a power supply device.

Then, a laser light source 48 is driven by a high voltage unit 47 in the detection head 43, and laser light 49 is emitted. The laser beam 49 is scanned in a fan shape by a polygon mirror 51, converted into parallel scanning beam by a lens 52, and irradiated onto the hard disk 41 from a light projector/receiver 53. Next, the reflected light is received by a light emitter/receiver 53 and condensed onto a light amount converter 56 via a lens 54 and a mirror 55.

The electrical signal converted by the photoelectric converter 56 is transmitted to the signal processing device 44, where it is compared with a predetermined threshold, that is, a slice level signal, and converted into a binary signal.

The binary signal is further transmitted to the microcomputer 45, and as described later, an array data file for one side of the hard disk 41 is created from this binary signal, and the surface of the hard disk 41 is processed by software processing the file data. The presence or absence of defects is inspected and the acceptability of the negative side is determined.

(Problem to be Solved by the Invention) By the way, as shown in FIGS. 4(a) and 4(b), the hard disk 41 has band-shaped discolored parts 58a and 58b, which are chuck marks, on the outer periphery thereof. There are many. Although the shape and number of the strip-shaped discolored portions 58a and 58b defined by the length and width in the circumferential direction are fixed, the electrical signal detected from these portions exceeds the slice level. However, since the strip-shaped discolored portions 58a and 58b themselves are not defects, they must be excluded from inspection for quality determination.

In other words, from point E, which is a normal area shown in FIG. 4(b), point F, which is a non-defect band-shaped discolored area, and point G, where defect 59 exists, points (a) and (b) in FIG. , (C) are obtained, these are compared with the slice level signal SL, and a binarized signal in which the portion above the slice level becomes "1" is output. Then, the "1" signal part becomes a black image, and an array data file 6o as shown in FIG. 4(C) is created. The circumferential direction is the column direction.

However, the inspection start position in the circumferential direction of the hard disk 41 cannot be determined, and it is not possible to distinguish between the band-shaped discolored parts 58a and 58b on the outer periphery and the defect 59 from the data file 60. For this reason, the outer peripheral portion 61 of the hard disk 41 is excluded from the inspection target area of the automatic inspection by the inspection device.
The quality of the hard disk is determined only by counting the number of defects in the area excluding the outer circumferential portion 61, and the outer circumferential portion 61 relies on visual inspection. Therefore, even if there is a defect in the outer periphery 61 that would be judged as defective, there is a risk that it will be erroneously judged as good.In order to avoid this erroneous judgment, it is practical to be able to automatically inspect the outer periphery 61 as well. A testing method with high quality was desired.

Accordingly, an object of the present invention is to provide a hard disk surface inspection method that can accurately detect defects in the outer circumference and improve practicality.

[Structure of the Invention] (Means for solving the problem) In order to solve the above problem, the present invention scans a light beam on a hard disk to be inspected, and detects changes in the level of reflected light exceeding a predetermined threshold. A hard disk surface inspection method in which a defect is detected and a non-defective portion of a fixed shape in which the level of reflected light changes above the threshold value is present on the outer periphery of the hard disk, the method comprising: detecting a defect; The gist is that the profile data of the defective part is obtained in advance as comparison profile data, and when the profile data obtained based on the level change of the reflected light does not correspond to the comparison profile data during inspection, it is determined that there is a defect. do.

(Operation) During the inspection, the profile data obtained based on the level change of the reflected light is compared with the comparative profile data obtained in advance, and when the two do not correspond, it is determined that there is a defect. Therefore, defects can be accurately detected by automatic inspection even on the outer periphery of the hard disk, thereby improving practicality.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 1(a) shows a hard disk 1 to be inspected, and the hard disk 1 in the example shown in the figure has a band-like discoloration on its outer periphery with the same length and width, that is, a non-defective portion with a fixed shape. A case is shown in which there are four portions 2 and a defect 3 occurs between the band-shaped discolored portions 2. In the figure, R is the radial direction and S is the circumferential direction.

For such a hard disk 1, an array data file 4 for the negative side of the hard disk 1 as shown in FIG. 1(b) is created using an inspection device similar to that shown in FIG. Can be stored. The array data file 4 in the example shown in the figure has 64 array data (0 to 63) in the radial direction R and 360 array data (0 to 359) in the circumferential direction S. There is. Hereinafter, the array data including the radial direction R and the circumferential direction S will be referred to as array data x (64, 360).

Note that the data of 0th and 359th "I" in the circumferential direction are continuous on the hard disk.
The area in the radial direction C to 63 in the array data file 4 indicates the outer peripheral area where the profile data of the strip-shaped discolored portion 2 exists. (C) and (d) of FIG. 1 respectively show circumferential direction profile data and radial direction profile data in this outer peripheral region.

In the surface inspection, the above-described array data file 4 is subjected to software processing to determine the presence or absence of defects, and based on this, the quality of the hard disk 1 is determined. The hard disk surface inspection method of this embodiment will be explained below using flowchart 1 in FIG.

First, the data number J of the circumferential array data is incremented from J-0 to 359 (step 11), and the data number I of the radial array data is incremented from I-C to 63 (step 13). By executing Steps 11 to 15, the value obtained by converting the allowable length range of the band-shaped discolored portion 2 into the number of data pieces, ~L2, is calculated from the array data X (64, 360) in the radial direction C~
63 profile data Y (360) is obtained (FIG. 1(d)) and stored in the memory within the microcomputer.

Here, Ll above indicates the minimum length conversion value of the band-like discolored portion, and L2 indicates the minimum length conversion value of the band-like discolored portion.

Next, after the number of pieces is cleared in step 16, the profile data Y (36
The length W and the number ICN of consecutive non-zero data in 0) are determined.

Next, the data Y(0) and Y(359), that is, the θth and 359th data in the circumferential direction, are continuous as described above, so these two data Y(0) and Y(359) are consecutive.
) are both not 0, (No in step 27.28)
), it is necessary to regard this as one band-shaped discolored area, so add the lengths of both data (step 29), and the number ICN is 1.
(step 30). In this way, the profile data for comparison is prepared.

Then, the number of consecutive non-zero data parts and the number N of band-shaped discolored parts 2 (N-4 in the example of FIG. 1(a)) are equal (
(Yes in step 31), and if the length W of each pig continuous portion is between L1 and L2 (step 32.3
3.34: Yes) There is no defect in the outer periphery of the hard disk, and the judgment is "OK" (step 35); otherwise, the judgment is "NG" (step 36).
.

In addition, in the case of the hard disk 1 shown in FIG. 1(a), the defect 3 has occurred on the outer periphery, so the number of consecutive non-zero data parts and the number N of band-like discolored parts are not equal, indicating a defect. It is judged as “NG”.

As described above, according to the hard disk surface inspection method of this embodiment, defects can be accurately detected by automatic inspection even on the outer periphery, and the quality of the entire hard disk can be accurately determined.

[Effects of the Invention] As explained above, according to the present invention, for the outer periphery of a hard disk, profile data obtained during inspection based on changes in the level of reflected light is used as a comparison profile of a non-defective area obtained in advance. By comparing the data with the data and determining that there is a defect when the two data do not correspond, it is possible to accurately detect defects on the outer periphery of the hard disk through automatic inspection, improving practicality. There are advantages.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a hard disk and array data files in an embodiment of the hard disk surface inspection method according to the present invention, FIG. 2 is a flowchart 1 for explaining the present invention in detail, and FIG. 3 is a conventional FIG. 4 is a diagram showing the hard disk and arrayed pig files in the hard disk surface inspection method using the same device, and FIG. 5 is a diagram showing the reflected light from the outer periphery of the pigeon disk shown in FIG. FIG. 3 is a signal waveform diagram showing an electrical signal obtained by conversion. 1 Nihard disk, 2, 4jl-shaped discolored area (non-defect area), 3: Defect. Agent Ji1no, IL: Miyoshi)Suwa Figure 2 (b) Figure 2 (c) Figure 8b Figure (C) Broom Figure 5

Claims (1)

[Claims] Scanning a light beam on a hard disk to be inspected,
A hard disk surface inspection method, wherein a defect is detected from a change in the level of reflected light exceeding a predetermined threshold, and a non-defective portion of a fixed shape in which the level of reflected light changes above the threshold is present on the outer periphery of the hard disk. For the outer peripheral portion of the hard disk, the profile data of the non-defective portion is obtained in advance as comparison profile data, and the profile data obtained based on the level change of the reflected light during the inspection does not correspond to the comparison profile data. A hard disk surface inspection method characterized in that a hard disk surface is determined to be defective when .