JPS62133374A - Inspection device for disk type recording medium - Google Patents

Abstract

PURPOSE:To reduce a device in cost and size by allowing the 2nd inspecting means to perform inspection regarding the state of a defect as to only a disk surface which is not decided on to have no defect. CONSTITUTION:When disk surfaces of the disk to be inspected begin to be read, a signal of a CH 1 is selected and outputted to a channel switching circuit 2. Consequently, signals of CHs 1-(n) are supplied to inspecting circuits 3 and 4 to make decisions 3 and 4 on whether or not the disk surfaces have a defect. When this decision making is finished and signals S1 and S2 indicating the decision results are supplied from the circuits 3 and 4, the signals of the CHs 1-(n) are outputted selectively to the circuit 2. Consequently, a precise decision on whether or not a disk surface which is not decided clearly on to have no defect has a defect is detected 3 successively and the size and position of a defect of a disk surface which is decided on to have the defect are detected 3, so that the detection results is displayed on a display means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inspection device for inspecting a disk-type recording medium, and particularly to an inspection device for inspecting a plurality of disk surfaces.

[Conventional technology]

In an inspection device that inspects the electromagnetic conversion characteristics of a magnetic disk, in order to increase inspection efficiency, a magnetic head is installed corresponding to each disk surface of a plurality of magnetic disks, and a magnetic head is installed on each disk surface of a plurality of magnetic disks in parallel. It is common to perform an inspection. Conventionally, in such inspection equipment, each magnetic head is equipped with a high-precision inspection circuit that determines whether the disk surface has a defect and detects the size and position of the defect on the disk surface. Correspondingly (that is, correspondingly to each disk surface of the magnetic disk to be inspected)
I was trying to set up multiple ones.

[Problem that the invention seeks to solve]

However, providing a plurality of such high-precision test circuits has the problem of increasing costs and increasing the size of the apparatus. Furthermore, if there are variations in the judgment speed or detection accuracy of each test circuit, there is a problem in that the reliability of the test is rather reduced.

This invention has been made to solve the above-mentioned problems.

[Means for solving problems]

A disk-type recording medium inspection apparatus according to the present invention determines whether or not there are defects on a plurality of disk surfaces based on read signals from a plurality of read/write heads corresponding to a plurality of disk surfaces of a disk-type recording medium to be inspected. a first inspection means that performs determination in parallel; and a selection means that selects read/write read signals corresponding to disk surfaces that are not determined to be defect-free by the first inspection means. and a second inspection means for at least inspecting the state of defects on the disk surface that is not determined to be defect-free based on the readout signal selected by the selection means. It is said that

[For production]

The second inspection means inspects the state of the defect (for example, detects the size and position of the defect on the disk surface) only on the disk surface that is not determined to be defect-free by the first inspection means. Therefore, the number of second inspection means may be smaller than the number of disk surfaces of the disk-type recording medium to be inspected. Further, since the first inspection means merely makes a determination as to whether or not there is a defect, it can be constructed easily and inexpensively. Therefore, the overall cost and size of the inspection device can be reduced.

As stated in claim 2, the first inspection means includes a relatively low-precision inspection means for determining whether a product clearly has a defect or not. In the case where the second inspection means is constituted by one high-precision inspection means that performs accurate judgment and inspection to determine the defect state (that is, the first inspection means first makes a judgment, and then the result is When a disk surface that has not been determined to have any obvious defects is finally subjected to accurate determination of the presence or absence of defects and inspection of the state of the defects using one second inspection means. (b) Since the first inspection means can be constructed more cheaply and simply, the cost reduction and miniaturization of the inspection apparatus are further promoted. In addition, since both the determination of the presence or absence of defects and the inspection of the defect status are ultimately performed by one second inspection means, the reliability of the inspection is affected by variations in the determination speed and inspection accuracy of each inspection means. There is no risk of a decrease in

Furthermore, as described in claim 3, when the second inspection means is also used as a part of the first inspection means, the amount of hardware of the first inspection means is reduced accordingly. Therefore, the cost and size of the inspection device can be further reduced. The following embodiments will be described using such an inspection device as an example.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a disk-type recording medium inspection apparatus according to the present invention. This testing device 1 tests the electromagnetic conversion characteristics of magnetic disks, and reads read signals (CH ( Channels) 1 to n (where n is a natural number of 2 or more) are given to this inspection device 1.

The device 1 is provided with a channel switching circuit 2.
All signals H1 to Hn are input to this circuit 2. The circuit 2 selects and outputs one signal from a plurality of input signals based on a signal applied to a control input. The output of the circuit 2 is provided in the device 1 and given to a test circuit B. The inspection circuit 3 determines the presence or absence of a defect (missing pulse error, extra pulse error, modulation error, etc.) on the disk surface and determines the size and position of the defect on the disk surface based on the readout signal from the magnetic helad. This is a highly accurate inspection circuit that performs detection.

The device 1 is also provided with one less number of test circuits 4 than C I 1-n, and one of the signals of CH1-n is
The remaining signals, for example, the signals of CH2 to CHn, are input to each test circuit 4 one by one. The inspection circuit 4 is a relatively low-accuracy inspection circuit (therefore, it is a relatively low-precision inspection circuit that only determines whether the disk surface clearly has the defect or not based on the read signal of the magnetic head). test circuit).

The signal S1 indicating the determination result of the presence or absence of a defect in the inspection circuit B is as follows:
The signal is applied to a sequence control unit 5 provided in the device 1. A signal S2 indicating the determination result of each test circuit 4 is also provided to the sequence control section 5, respectively. The sequence control section 5 controls these signals S1. Based on S2, a signal for controlling the selection operation of the channel switching circuit 2 is applied to the control input of the circuit 2.

A signal S3 indicating the detection result of the size and position of the defect in the inspection circuit B is given to a display means (not shown) and displayed.

Next, an example of the inspection operation of this inspection apparatus 1 will be explained with reference to FIG. 2. FIG. 2 is a flowchart schematically showing an example of a computer program executed by the sequence control unit 5. As shown in FIG. When the reading of each disk surface of the disk to be inspected is started, first, the channel switching circuit 2 is
1 signal is selectively output (step 101). As a result, the signals of CH1 to CHn are given to the test circuits 6 and 4,
Judgments regarding the presence or absence of defects on each disk surface are made in parallel by inspection circuits 6 and 4.

When this judgment is completed and signals S1 and S2 indicating the judgment result are given from the inspection circuits 6 and 4, signals S1 and S2 indicating the judgment result are given to the inspection circuits 6 and 4 that have not judged that there is no obvious defect. The channel switching circuit 2 selectively outputs the signals of CH1 to CHn sequentially (step 102). As a result, for disk surfaces that have not been determined to be clearly defective, the inspection circuit B sequentially performs accurate determination of the presence or absence of defects. As for the disk surface that is determined to have a defect as a result, the size and position of the defect on the disk surface are similarly detected by the inspection circuit B, and the detection results are displayed on a display means (not shown).

In this way, this inspection device 1 is provided with an inspection circuit 3 having an inexpensive and simple configuration and one inspection circuit 4 with high precision, and these inspection circuits 6 and 4 first make a determination as to whether or not there are defects on each disk surface. As a result, the inspection circuit 4 accurately determines the presence or absence of a defect and detects the size and position of the defect for those disk surfaces that are determined not to have any defects. That's what I do. Therefore, unlike an inspection apparatus in which a high-precision inspection circuit such as the inspection circuit 4 is provided for each magnetic head corresponding to each disk surface and high-precision inspection is performed in parallel, the cost and size of the apparatus can be reduced. In addition, it is possible to prevent a decrease in test reliability due to variations in judgment accuracy and detection accuracy of each test circuit.

In this embodiment, a magnetic disk is inspected, but other disk-type recording media may be inspected.

〔Effect of the invention〕

As described above, according to the disk-type recording medium inspection apparatus according to the present invention, it is possible to reduce the cost and size of the apparatus.

Furthermore, when the first inspection means and the second inspection means are configured as claimed in claim 2, it is possible to further reduce the cost and size of the apparatus, and each inspection means can be further reduced in cost and size. It is possible to prevent a decrease in test reliability due to variations in judgment accuracy and test accuracy.

Furthermore, when the second inspection means is also used as a part of the first inspection means as claimed in claim 3, it is possible to further reduce the cost and size of the apparatus.

[Brief explanation of drawings]

FIG. 1 is an electrical block diagram showing an embodiment of a disk-type recording medium inspection device according to the present invention, and FIG. 2 schematically shows an example of a computer program executed by the sequence control section of the inspection device shown in FIG. This is a flowchart. DESCRIPTION OF SYMBOLS 1... Inspection device, 2... Channel switching circuit, 6° 4... Inspection circuit, 5... Sequence control section.

Claims (1)

[Claims] 1. Based on the read signals of a plurality of read/write heads corresponding to a plurality of disk surfaces of a disk-type recording medium to be inspected, the presence or absence of defects is determined in parallel for the plurality of disk surfaces. a selection means for selecting a read signal of a read/write head corresponding to a disk surface that is not determined to be defect-free by the first inspection means; and second inspection means for at least inspecting the state of defects on the disk surface that is determined to be free of defects based on the readout signal. Inspection equipment. 2. The first inspection means includes a relatively low-precision detection means for determining whether a product clearly does not have a defect or not, and the second inspection means includes a detection means that accurately determines the presence or absence of a defect. 2. The disk-type recording medium inspection apparatus according to claim 1, which comprises one highly accurate inspection means for inspecting the state of defects. 3. The second inspection means is also used as a part of the first inspection means when determinations regarding the presence or absence of defects are made in parallel on a plurality of disk surfaces; or 3. The inspection device for a disk-type recording medium according to item 2.