JPH0687303B2 - Inspection device for disk type recording media - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for inspecting a disk type recording medium, and more particularly to an inspection apparatus 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 the efficiency of the inspection, a magnetic head is provided for each disk surface of a plurality of magnetic disks, and these disk surfaces are arranged in parallel. It is common to conduct an inspection. In such an inspection apparatus, conventionally, each magnetic head is provided with a highly accurate inspection circuit that determines whether or not the disk surface has a defect and detects the size and position of the defect on the disk surface. Corresponding (that is, corresponding to each disk surface of the magnetic disk to be inspected)
I was planning to provide more than one.

[Problems to be solved by the invention]

However, providing a plurality of highly accurate inspection circuits in this way raises the cost and the size of the apparatus. Further, if there is a variation in the judgment speed or detection accuracy of each inspection circuit, there is a problem that the reliability of the inspection is rather lowered.

The present invention has been made to solve the above problems.

[Means for solving problems]

A disc-type recording medium inspection apparatus according to the present invention, based on read signals of a plurality of read / write heads corresponding to a plurality of disc surfaces of a disc-type recording medium to be inspected,
A relatively low-precision first inspecting unit that makes a determination as to whether or not there is a defect in parallel with respect to the plurality of disc surfaces, and a disc surface that is not determined to have no defect by the first inspecting unit. Based on the read signal selected by the selecting means for selecting the read signal of the read / write head corresponding to, the disc surface which is not determined to have no defect is accurately determined whether or not there is a defect. It is characterized in that it is provided with a high-precision second inspection means for making a judgment and an inspection regarding the state of defects.

[Action]

In the present invention, first, a relatively low-precision first inspecting means that only makes a determination as to the presence or absence of a defect is first used to make a determination, and as a result of the determination, it is not determined that the defect is not apparently present. Only for the disk surface, one highly accurate second inspection means is finally used to accurately determine the presence / absence of a defect and to inspect the state of the defect. Since the number of the second inspection means that can be simply configured and has high accuracy is only one, the cost and size of the inspection apparatus can be reduced as a whole. In addition, since the presence / absence of a defect and the inspection of the state of the defect are finally performed by one second inspection means, the inspection speed depends on the determination speed and the inspection accuracy of each inspection means. There is no fear of deterioration of reliability.

Further, when the second inspection means is also used as a part of the first inspection means as described in claim 2, the hardware amount of the first inspection means is reduced accordingly. Therefore, cost reduction and size reduction of the inspection device are further promoted. In the following embodiments, such an inspection device will be described as an example.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a disc type recording medium inspection apparatus according to the present invention. This inspection device 1 is for inspecting the electromagnetic conversion characteristics of a magnetic disk, and reads signals from a plurality of magnetic heads (CH (not shown) corresponding to the disk surfaces of a plurality of magnetic disks to be inspected (not shown) on a one-to-one basis. Channels 1 to n (where n is a signal of a natural number of 2 or more) are supplied to the inspection apparatus 1.

The device 1 is provided with a channel switching circuit 2, and CH
All signals 1 to n are input to this circuit 2. Circuit 2 is
One signal is selected from a plurality of input signals and output based on the signal given to the control input. The output of the circuit 2 is given to the inspection circuit 3 provided in the device 1. The inspection circuit 3 judges the presence or absence of defects (missing pulse error, extra pulse error, modulation error, etc.) on the disk surface based on the read signal of the magnetic head, and detects the size and position of the defect on the disk surface. This is a high-precision inspection circuit that performs and.

The device 1 is also provided with one less number of test circuits 4 than CH1 to n, and the remaining signals except one of the signals of CH1 to n, for example, the signals of CH2 to n, respectively. One signal is input to the inspection circuit 4. The inspection circuit 4 is a relatively low-precision inspection circuit that determines only whether the disk surface clearly has the defect or not, based on the read signal of the magnetic head. Inspection circuit).

The signal S1 indicating the determination result of the presence or absence of the defect of the inspection circuit 3 is given to the sequence control unit 5 provided in the device 1. The signal S2 indicating the determination result of each inspection circuit 4 is also given to the sequence control unit 5, respectively. The sequence control unit 5 sends a signal for controlling the selection operation of the channel switching circuit 2 based on these signals S1 and S2.
Is given to the control input of.

The signal S3 indicating the detection result of the size and position of the defect of the inspection circuit 3 is given to the display means (not shown) and displayed.

Next, an example of the inspection operation of the inspection device 1 will be described with reference to FIG. FIG. 2 is a flow chart schematically showing an example of a computer program executed by the sequence control unit 5. When the reading of each disk surface of the disk to be inspected is started, CH1 is first transferred to the channel switching circuit 2.
Signal is selectively output (step 101). As a result, the signals of CH1 to CHn are given to the inspection circuits 3 and 4, and the inspection circuits 3 and 4 judge in parallel whether or not there is a defect on each disk surface.

When this judgment is completed and the signals S1 and S2 indicating the judgment result are given from the inspection circuits 3 and 4, the inspection circuits 3 and 4 which are not judged to have no defects are given to the inspection circuits 3 and 4. CH1 to n signals that are being transmitted sequentially to the channel switching circuit 2
To be selectively output (step 102). As a result, the inspection circuit 3 sequentially makes an accurate determination of the presence / absence of a defect on the disk surface which is not determined to have no defect. As a result, with respect to the disk surface determined to have a defect, the size and position of the defect on the disk surface are similarly detected by the inspection circuit 3, and the detection result is displayed on the display means (not shown).

As described above, the inspection apparatus 1 is provided with the inspection circuit 4 having a low cost and a simple structure and the highly accurate one inspection circuit 3, and these inspection circuits 3 and 4 first determine the presence or absence of a defect on each disk surface. As a result, the inspection circuit 3 finally performs the accurate determination of the presence / absence of a defect and the detection of the size and position of the defect on the disk surface that is not determined to have no defect as a result. ing. Therefore, unlike a testing apparatus that provides a highly accurate testing circuit such as the testing circuit 4 for each magnetic head corresponding to each disk surface and performs highly accurate testing in parallel, the cost and size of the apparatus are reduced. In addition, it is possible to prevent deterioration of the reliability of the inspection due to the variation of the determination accuracy and the detection accuracy of each inspection circuit.

Although the magnetic disk is inspected in this embodiment, other disk type recording media may be inspected.

〔The invention's effect〕

As described above, according to the disc-type recording medium inspection apparatus of the present invention, it is possible to reduce the cost and size of the apparatus, and to improve the reliability of the inspection due to the determination accuracy of each inspection means and the variation of the inspection accuracy. The decrease can be prevented.

Further, when the second inspection means is also used as a part of the first inspection means as in claim 2, the cost and size of the apparatus can be further reduced.

[Brief description of drawings]

FIG. 1 is an electrical block diagram showing an embodiment of a disc type recording medium inspection device according to the present invention, and FIG. 2 is a schematic diagram showing an example of a computer program executed by a sequence control unit of the inspection device of FIG. It is a flowchart to do. 1 …… Inspection device, 2 …… Channel switching circuit, 3,4 ……
Inspection circuit, 5 ... Sequence control unit.

Claims (2)

[Claims] 1. A method for making a determination as to whether or not there is a defect 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 low-accuracy first inspection means, a selection means for selecting a read signal of the read / write head corresponding to a disk surface which is not determined to have no defect by the first inspection means, and the selection means High-accuracy second inspection means for accurately determining the presence / absence of a defect and inspecting the defect state of the disk surface that is not determined to have no defect based on the selected read signal. An inspection device for a disk-type recording medium, which is provided. 2. The second inspecting means is also used as a part of the first inspecting means when the determination as to the presence or absence of a defect is made in parallel on a plurality of disk surfaces. An inspection device for a disc-type recording medium according to item 1.