JP2824864B2 - Disk defect inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk defect inspection apparatus that performs a process of taking in coordinate data indicating the position of a disk defect.

2. Description of the Related Art An information recording medium such as a magnetic disk, an optical disk, or a magneto-optical disk is inspected by a disk defect inspection apparatus because the quality of data recording performance deteriorates when the surface has a defect. For inspection, an optical method using a laser is used.

2 (a), 2 (b) and 2 (c), an outline of a disk defect, a basic optical system of a disk defect inspection apparatus using a laser, and a method of displaying defect data will be described. In FIG. 1 (a), reference numeral 1 denotes each of the above-mentioned disks, in which isolated defects (a), linearly continuous line defects (b), or planar surface defects (c) are randomly distributed on the surface. doing. In FIG. 2B, a disk 1 is a spindle 2
The light source 3 emits a laser beam to form a spot Sp on the surface of the disk. The spot Sp moves in the direction of the radius R and scans the surface in a spiral manner. If there is a defect, scattered light is generated. The scattered light is condensed by the condenser lens 4 and received by the light receiver 5 composed of a photoelectric converter. Various kinds of defects are detected, and defect signals are taken into the microprocessor. The above optical system is a basic one, and various optical systems are used in combination to efficiently detect various defects, respectively, and the light receiving signal of the light receiver is identified by various thresholds. The size of the defect is used as defect data.

The defect data obtained as described above is appropriately aggregated, and displayed on a display as a map indicating the location of the defect so as to facilitate observation and evaluation. For the map display, the circumferential angle θ and the radius R of the disk are divided into minute Δθ and Δr, respectively, as shown in FIG. Here, Δθ is divided by an angle pulse obtained from a rotary encoder of the disk rotating mechanism, and Δ
The division of r is performed by moving the spot Sp with respect to the rotation of the disk. Therefore, Δ for spot Sp
The coordinates of S are obtained by counting the angle pulse and the number of rotations, and the coordinates of ΔS at the time when the defect signal is input are stored in the memory and used for map display.

[Problem to be Solved] Recently, as the recording density of a disk has increased, the allowable defect size has become smaller and smaller, and the unit cell ΔS needs to be further reduced accordingly. It is. For example, conventionally, ΔS and Δr were approximately 0.25 mm ^{2 when} Δθ and Δr were up to 0.5 mm.
Δr is set to 1/50 or less, and ΔS is set to 1 / 2,500.
It may be minute below. As described above, the defect is stored in the memory for each coordinate of the unit cell ΔS. Therefore, when ΔS is reduced, it is necessary to increase the memory capacity by 2500 times or more with respect to the above example. On the other hand, in the case of an optical disk, an inspection is performed even at the stage when a groove (groove) is formed, and the crushed groove is regarded as a defect. Much more and more memory capacity is required. On the other hand, it is desirable to compress the defect data for each unit cell ΔS as much as possible so as not to disturb the map display and to save the memory capacity.

The present invention has been made in view of the above, and an object of the present invention is to provide a disk defect inspection apparatus that performs a defect coordinate acquisition process that does not hinder the display of a map of defect data and saves memory capacity. It is assumed that.

[Means for Solving the Problems] A feature of the disk defect inspection apparatus of the present invention for achieving the above object is that the disk defect inspection apparatus has a processor and is capable of detecting a defect signal for a defect of a disk to be inspected obtained by an inspection optical system. In a disk defect inspection apparatus that stores the coordinates of a circumferential angle and a radial position with respect to a defect signal in a memory by an angle pulse output from a rotary encoder, and displays a defect on a map corresponding to the coordinates by processing of a processor. A start point / end point detection circuit for generating a start point pulse and an end point pulse for the start point and the end point of the defect in response to the defect signal and the angle pulse, and a signal for writing data and an address update for the start point pulse and the end point pulse, respectively. Receiving as a signal, storing the coordinates of the circumferential angle and radial position of the disk with respect to the start point and the end point. Memory and
The processor includes a processor for reading out the coordinates of the circumferential angle and the radial position from the memory and displaying a continuous defect on a map in a continuous state.

In this method, a start pulse and an end pulse are generated, and the start pulse and the end pulse are used as a signal for writing data to the memory and a signal for updating an address, respectively. The coordinates are stored in the coordinate memory of the radius position and the radius position, and the continuous defect is displayed as a map in a continuous state by the processing of the microprocessor.

As a specific example of the circuit for generating the start point pulse and the end point pulse, a defect signal is input to a start point / end point detection circuit including two flip-flops, an exclusive OR circuit, and an AND circuit, and an angle pulse is generated as a trigger. Things.

[Operation] In the above-described disk defect inspection apparatus, the coordinates of the circumferential angle and the radial position with respect to the start point and the end point are written to the memory in correspondence with the start point pulse and the end point pulse by the start point pulse and the end point pulse for the start point and the end point of the defect. The address is updated and the data stored in the memory is processed by the microprocessor to display a continuous defect map in a continuous state. The coordinates of all points of the continuous defect are displayed. Is not required, and the memory capacity can be greatly reduced. The start point pulse and the end point pulse are easily generated by inputting a defect signal to a start point / end point detection circuit and using an angle pulse from a rotary encoder as a trigger.

As described above, the intermediate point data is generated by generating the start point pulse and the end point pulse, and using the start point pulse and the end point pulse as a signal for writing data to the memory and a signal for updating the address, respectively. Since the coordinate data of the defect can be directly stored in the memory in correspondence with the detected defect without performing the operation, the storage capacity of the memory can be saved and the circuit configuration can be simplified.

[Embodiment] FIGS. 1A, 1B, and 1C illustrate a block configuration of a disk defect inspection apparatus in a disk defect inspection apparatus according to an embodiment of the present invention, a start point / end point detection circuit, and an operation thereof. 4 shows a time chart of a signal waveform to be generated. In FIG. 7A, a light receiving signal of scattered light due to a defect is output from the light receiving device 5, appropriately amplified by the amplifier 6, and input to the + terminal of the comparator 7. On the other hand, an appropriate digital threshold value [SL] supplied from the microprocessor (MPU) 9 is given to the-terminal by the D / A converter 9a as an analog amount SL, and a defect is identified. The defect signal Pd is input to the start point / end point detection circuit 8. On the other hand, the rotary encoder (EN
C) An angular pulse [Δθ] output by 10 is input, and using this as a trigger, a start point pulse and an end point pulse for the start point and end point of the defect signal are generated, and these are input to the defect counter 13 and counted. The counted number is given to the RAMs 14a and 14b as an address signal. On the other hand, the angle pulse [Δθ] is input to the θ counter 12a to obtain data [θ] of the disk rotation angle, and the [0 °] signal indicating the reference point of the rotation angle θ output from the ENC 10 is R. counter
The data [R] of the radial position is obtained by counting by 12b. The data [θ] and [R] are stored in the RAMs 14a and 14b at the addresses of the above-mentioned addresses, respectively, using the start pulse and the end pulse as enable (EN) signals. The stored data [θ] and [R] are processed by MPU9 and displayed
9b, and the defect is displayed as a map corresponding to the coordinates. If the defects are continuous, they are displayed in a continuous state.

1 (b) and 1 (c), a start point / end point detection circuit 8
And its operation will be described. In the start point / end point detection circuit 8 shown in FIG. 2B, two flip-flops (FF ₁ ) 8a and (FF ₂ ) 8b are connected as shown in the figure, and the outputs Q ₁ and Q ₂ of both are exclusive OR circuits 8
Input to the AND circuit 8d via c. Also, (FF ₁ ) 8a, (F
F ₂ ) An angle pulse [Δθ] is given to 8b and the AND circuit 8d. On the other hand, in FIG. 3C, the light receiving signal of the light receiver 5 is represented by (a), which is identified by the threshold value [SL] in the comparator 7 to obtain the defect signal Pd. When the defect signal Pd is input to the D terminal of (FF ₁ ) 8a, Q is determined by [Δθ].
₁ becomes "1" and this is given to the D terminal of (FF ₂ ) 8b. Since at this point Q ₂ is "0", although exclusive from OR circuit 8c "1" is output, the output of the exclusive OR circuit 8c Q ₂ by the following [[Delta] [theta]] is "1" to "0 And the output during this time is the start signal ps. Q ₁ a defect signal Pd is completed "0"
However, since Q ₂ is “1” for one [Δθ],
In the meantime, the end point signal pe is output. Here, when the defect signal is short as shown in (b) of FIG. 9B and is equal to or less than [Δθ], the start signal ps and the end signal pe are continuous as shown in FIG. Need to be separated. Then, these are separated by AND synthesis of these and [Δθ] by the AND circuit 8d to generate a start point or end point pulse pC.

The disk defect inspection device that performs the above-described defect coordinate capturing process is for a defect signal identified by a single threshold value SL, but an actual disk defect inspection device combines various optical systems as described above, Further, the size of the defect is detected by using the threshold value SL in a plurality of stages, and a disk defect inspection device that performs the above-described coordinate capturing process for each of the optical systems or the defect signals obtained by the plurality of threshold values is applied. Then, the obtained defect data can be aggregated by the MPU and displayed on one map.

[Effects of the Invention] As is apparent from the above description, in the disk defect inspection apparatus according to the present invention, the coordinates of the circumferential angle and the radial position with respect to the start point and the end point of the defect are stored in the memory in correspondence with the start point pulse and the end point pulse. The addresses written are updated and the data stored in this memory are processed by the microprocessor to display a continuous defect map in a continuous state, and the coordinates of all points of the continuous defect are required. However, the memory capacity can be greatly reduced, and the effect obtained by applying the present invention to a defect inspection apparatus for various types of high-density disks used for information recording media is significant.

[Brief description of the drawings]

FIGS. 1 (a), 1 (b) and 1 (c) are a block diagram of an embodiment of a disk defect inspection apparatus according to the present invention, a start point / end point detection circuit and a time chart of signal waveforms for its operation, and FIG. (A), (b) and (c)
FIG. 2 is an explanatory diagram of a defect of the disk, a basic configuration diagram of an optical system of the disk inspection device, and an explanatory diagram of a map display method of defect data. DESCRIPTION OF SYMBOLS 1 ... Disc, 2 ... Spindle, 3 ... Light source, 4 ... Condensing lens, 5 ... Receiver, 6 ... Amplifier, 7 ... Comparator, 8 ... Start point / end point detection circuit, 8a ... Flip-flop (FF ₁ ), 8b… Flip-flop (FF ₂ ), 8c… Exclusive OR circuit, 8d… AND circuit, 9… Microprocessor (MPU), 9a… D / A converter, 9b… ... Display, 10 ... Rotary encoder (ENC), 11 ... Theta counter, 12 ... R counter, 13 ... Defect number counter, 14a, 14b ... RAM.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/26 G11B 20/18

Claims (2)

(57) [Claims] A defect signal for a defect of a disk to be inspected obtained by an inspection optical system is provided.
By the angle pulse output from the rotary encoder,
In a disk defect inspection apparatus that stores coordinates of a circumferential angle and a radial position with respect to the defect signal in a memory and displays the defect on a map corresponding to the coordinates by the processing of the processor, the defect signal, the angle pulse, A start point / end point detection circuit for generating a start point pulse and an end point pulse for the start point and the end point of the defect, and receiving the start point pulse and the end point pulse as a signal for writing data and a signal for updating an address, The memory for storing the coordinates of the circumferential angle and the radial position of the disk with respect to the start point and the end point, and reading the coordinates of the circumferential angle and the radial position from the memory and displaying a continuous defect in a map in a continuous state; A disk defect inspection apparatus comprising: the processor that performs processing. 2. The start point / end point detection circuit has a two-stage flip-flop and an exclusive OR circuit, and a preceding one of the two stages receives the defect signal, and the two-stage flip-flop is 2. The disk defect inspection apparatus according to claim 1, wherein the start pulse and the end pulse are generated by using the angle pulse as a trigger and taking out the outputs of the two-stage flip-flops through the exclusive OR circuit.