JP2012154740A - Center deviation measuring device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a center deviation measuring device and a method therefor capable of reducing time needed for measuring center deviation of the inner periphery and the outer periphery of a disk-shaped substrate having a circular hole in the central part.SOLUTION: A center deviation measuring device for measuring center deviation of the inner periphery and the outer periphery of a disk-shaped substrate W having a circular hole in the central part is provided with: a measuring part which measures the radial width B of the main plane S between the inner peripheral end surface C1 and the outer peripheral end surface C2 in a measuring region DA formed in between a light projection part and a light receiving part, over the whole periphery of the disk-shaped substrate in a non-contact state; and a calculation part for calculating the center deviation by calculating the difference A between the maximum value Bmax and the minimum value Bmin of the radial width B measured by the measuring part and using the difference A.

Description

  The present invention relates to a technique for measuring a deviation between an inner circumference center and an outer circumference center of a disk-shaped substrate having a circular hole in a central portion.

  For example, in the manufacturing process of a glass or aluminum magnetic disk substrate, the concentricity of the inner periphery and the outer periphery is measured and managed. In general, the concentricity is obtained by measuring the inner and outer peripheral end surfaces of a disk substrate with a contact or non-contact sensor, obtaining the centers of the inner and outer circles, and calculating the distance between the centers. Is measured.

  For example, Patent Documents 1 and 2 are cited as prior art documents for obtaining the centers of two circumferences and measuring the concentricity based on the distance between the centers. Patent Documents 1 and 2 disclose measurement techniques using non-contact sensors.

JP 2002-54917 A JP 2008-171532 A

  Certainly, in the case of the above-described prior art, it is possible to accurately measure the misalignment between the two circumferences. However, since the centers of the two circumferences must be obtained, there is a disadvantage that it takes time to measure the deviation between the centers. Therefore, for example, when the measurement is frequently performed for process management, the conventional measurement method is not suitable.

  Therefore, an object of the present invention is to provide a center deviation measuring apparatus and method for reducing the time required to measure the center deviation between the inner circumference and the outer circumference of a disc-shaped substrate having a circular hole in the center.

In order to achieve the above object, a center deviation measuring apparatus according to the present invention is:
A center deviation measuring device for measuring the center deviation between the inner circumference and the outer circumference of a disc-shaped substrate having a circular hole in the center,
A measurement unit that measures the radial width of the main plane sandwiched between the inner periphery and the outer periphery over the entire circumference of the disk-shaped substrate;
A calculation unit that calculates a difference between the maximum value and the minimum value of the radial width measured by the measurement unit and calculates a center shift using the difference;
It is characterized by providing.

In order to achieve the above object, the center deviation measuring method according to the present invention is:
A center deviation measuring method for measuring the center deviation of the inner circumference and outer circumference of a disc-shaped substrate having a circular hole in the center,
A measuring step of measuring the radial width of the main plane sandwiched between the inner periphery and the outer periphery over the entire circumference of the disc-shaped substrate;
A calculation step of calculating a difference between the maximum value and the minimum value of the measured radial width;
It is characterized by having.

In order to achieve the above object, the center deviation measuring method according to the present invention is:
A center deviation measuring method for measuring the center deviation of the inner circumference and outer circumference of a disc-shaped substrate having a circular hole in the center,
From the storage container that stores a plurality of disk-shaped substrates having a circular hole in the center in a standing state, the stored disk-shaped substrates are lifted and detached in a standing state by an elevating mechanism,
Rotate the detached disk-shaped substrate in the circumferential direction of the disk-shaped substrate,
A measurement process for measuring the radial width of the main plane of the rotated disk-shaped substrate over the entire circumference;
The disk-shaped substrate whose radial width is measured is lowered by the lifting mechanism and returned to the storage container,
Pitch movement for moving the horizontal relative position of the storage container and the lifting mechanism so that another disk-shaped substrate stored in the storage container is lifted and removed from the storage container by the lifting mechanism Process,
And a calculation step of calculating a difference between the maximum value and the minimum value of the radial width measured in the measurement step and calculating a center deviation using the difference.

  ADVANTAGE OF THE INVENTION According to this invention, the time which measures the center shift | offset | difference of the inner periphery center and outer periphery center of a disk shaped board | substrate which has a circular hole in the center part can be shortened.

It is the figure which showed the case where the center shift | offset | difference of the inner periphery and outer periphery of the glass substrate W is measured by this invention. It is the figure which showed another aspect of measurement area | region DA. It is the figure which showed another aspect of measurement area | region DA. It is the figure which showed another aspect of measurement area | region DA. It is a figure for demonstrating the center deviation measuring method of this invention. It is a side view of center shift measuring device 1 which is one embodiment of the present invention. FIG. 3 is a perspective view showing a first specific example of a rotation mechanism 10. It is sectional drawing of the rotation mechanism 10 in EE shown in FIG. 5 is a perspective view illustrating a second specific example of the rotation mechanism 10. FIG. FIG. 6 is a schematic diagram illustrating a third specific example of the rotation mechanism 10. It is a figure for demonstrating the apparatus which measures the center shift | offset | difference of the several glass substrate W accommodated in the cassette 40 using the rotation mechanism 10 shown in FIG. FIG. 5 is a diagram for explaining a method for measuring the center deviation of a plurality of glass substrates W housed in a cassette 40.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1A is a diagram showing a case where the center deviation between the inner periphery and the outer periphery of the glass substrate W for magnetic recording medium is measured by the present invention. The glass substrate W is a donut-shaped disk-shaped substrate having a circular hole formed in the center. The main plane S is a planar annular surface sandwiched between the outer peripheral end surface C2 of the glass substrate W and the inner peripheral end surface C1 of the central circular hole. The radial width B of the main plane S corresponds to the radial dimension of the glass substrate W of the main plane S.

  FIG. 2 is a view for explaining the center deviation between the inner periphery and the outer periphery of the glass substrate W. FIG. When the glass substrate W is rotated once in the circumferential direction around the center circular hole as the rotation center, the maximum value in the radial width B over the entire circumference of the main plane S corresponds to Bmax, The smallest value in the radial width B over the circumference corresponds to Bmin. In this case, since the difference A between the maximum value Bmax and the minimum value Bmin is a value corresponding to the concentricity between the inner periphery and the outer periphery of the glass substrate W, the difference A is determined as the center deviation between the outer periphery and the inner periphery of the glass substrate W. It can be used as a value representing the degree of. That is, the larger the absolute value of the difference A, the larger the center deviation between the outer periphery and the inner circumference of the glass substrate W. The smaller the absolute value of the difference A, the smaller the center deviation, and the difference A is zero. Indicates that there is no misalignment.

  That is, the radial width B of the main plane S sandwiched between the inner peripheral end surface C1 and the outer peripheral end surface C2 of the glass substrate W is measured over the entire circumference, and the maximum value Bmax of the measured radial width B for the entire circumference is measured. By calculating the difference A of the minimum value Bmin and calculating the center deviation using the difference A, the center deviation between the inner periphery and the outer periphery of the glass substrate W can be measured. According to this method, since it is not necessary to obtain the centers of the inner periphery and the outer periphery in order to measure the center deviation between the inner periphery and the outer periphery of the glass substrate W, it is possible to shorten the time for measuring the center deviation.

  In order to measure the radial width B of the main plane S over the entire circumference, for example, as shown in FIG. 1A, the main plane S is passed over the entire circumference in a predetermined measurement area DA for measuring the radial width B. You can do it. Specifically, the glass substrate W may be rotated once or more in the circumferential direction of the glass substrate W around the central hole as a rotation center. In order to stabilize the measurement of the radial width B, it is preferable that the speed (specifically, the angular speed of rotation) at which the main plane S passes through the measurement area DA is constant.

  The measurement area DA does not have to be sized so as to include the entire main plane S of the glass substrate W. In order to prevent erroneous measurement of the radial width B, the measurement area DA has a part of the inner peripheral end face C1 and a part of the outer peripheral end face C2 that define the radial width B of the main plane S in one radial direction of the glass substrate W. It is sufficient if the size includes. If it is desired to further shorten the measurement time, the measurement area DA should be expanded. For example, the measurement area DA may be expanded as shown in FIG. 1B, or two or more measurement areas DA may be provided as shown in FIG. 1C and FIG. 1D, and the rotation of the glass substrate W may be half or less.

  FIG. 3 is a side view of the center deviation measuring apparatus 1 according to an embodiment of the present invention. The center deviation measuring apparatus 1 includes a light projecting unit 12 and a light receiving unit 11 as a measuring unit having a radial width B. A measurement area DA is formed in a space sandwiched between the light projecting surface 14 of the light projecting unit 12 and the light receiving surface 13 of the light receiving unit 11. The light projecting unit 12 is disposed below the mounting position of the glass substrate W so that the light projecting surface 14 faces upward. The light receiving unit 11 is installed on the upper side of the support column 15 and is arranged on the upper side with respect to the attachment position of the glass substrate W so that the light receiving surface 13 faces downward. By facing the light receiving surface 13 downward, other disturbance light such as a fluorescent lamp on the ceiling is prevented from entering the light receiving surface 13 as compared with the case where the light receiving surface 13 faces upward, thereby preventing erroneous measurement of the radial width B. be able to.

  The light projecting unit 12 irradiates light toward the glass substrate W from the normal direction of the main plane S (Z-axis direction in the case of FIG. 3). The light projecting unit 12 includes, for example, a light source 21 and a lens 22. In terms of improving the measurement accuracy of the radial width B, a suitable example of the light source 21 is a light emitting diode, and a more preferred example is a gallium nitride light emitting diode. On the other hand, the lens 22 is an optical component that forms the measurement area DA. The lens 22 is preferably a collimator lens that converts light emitted from the light source 21 into parallel light in order to stably form the measurement area DA. The light from the light source 21 is condensed by the lens 22 onto a part in the radial direction between the inner peripheral end face C1 and the outer peripheral end face C2 in the entire area of the main plane S.

  The light receiving unit 11 receives light arriving from the direction of the main plane S of the glass substrate W. The radial width B is measured based on the bright and dark edge positions of the light received by the light receiving unit 11. For example, the light receiving unit 11 forms an image of the glass substrate W irradiated with light from the light projecting unit 12 on a CCD image sensor (imaging device) 25 via the telecentric lens 23. The light receiving unit 11 may include a beam splitter 24 and divide the image on the glass substrate W into the CCD image sensor 25 and the CMOS image sensor 26.

  The calculation unit 16 of the center deviation measuring device 1 measures the edges (inner peripheral end surface C1 and outer peripheral end surface C2) of the main plane S based on the light reception signal transmitted from the CCD image sensor 25 of the light receiving unit 11, and the radial direction. The maximum value Bmax and the minimum value Bmin of the width B are derived. Then, the calculation unit 16 calculates a difference A between the maximum value Bmax and the minimum value min and outputs the calculation result of the difference A to the output unit 17. The arithmetic unit 16 may be configured by an AD converter, a CPU, or the like. The output unit 17 may be, for example, a display, a printer, a speaker, or any combination thereof. The output unit 17 may display an image obtained by the CMOS image sensor 26 of the light receiving unit 11.

  Further, the center deviation measuring apparatus 1 includes a rotation mechanism 10 as a movable mechanism that allows the main plane S of the glass substrate W to pass through the measurement area DA over the entire circumference. The rotation mechanism 10 is means for rotating the glass substrate W in the XY plane by a motor in the circumferential direction around the center circular hole. The rotation mechanism 10 is fixed by a pedestal 18.

  FIG. 4 is a perspective view showing a first specific example of the rotation mechanism 10. The rotation mechanism 10 includes a turntable 32 that rotates the glass substrate W, a central shaft 33 that positions the glass substrate W, and a housing 31 that houses a motor and the like that rotates the turntable 32. A glass substrate W is placed on the upper surface 32 a of the turntable 32. The central axis 33 having a cylindrical outer shape is a member for positioning the glass substrate W by fitting a circular hole at the center of the glass substrate W from above. The turntable 32 rotates within the XY plane in the circumferential direction of the glass substrate W, but the central axis 33 is a fixed member that does not rotate. A groove 34 is formed in the central axis 33 so that light emitted from the light projecting unit 12 passes through the inner peripheral end face C1 of the glass substrate W and reaches the light receiving unit 11.

  FIG. 5 is a cross-sectional view of the rotation mechanism 10 taken along the line EE shown in FIG. A glass substrate W as an object to be measured is placed on the upper surface of the turntable 32. The turntable 32 of the rotation mechanism 10 rotates the glass substrate W while sliding the inner peripheral end surface C1 of the glass substrate W in contact with the side surface 33a of the central shaft 33. The groove 34 is formed on the central axis 33 so as to extend in the normal direction of the main plane S of the glass substrate W as a path of light reaching the light receiving unit 11 from the light projecting unit 12 through the inner peripheral end face C1. It is a notch. By providing the groove 34, the light that has passed through the gap between the side surface of the central shaft 33 and the inner cylindrical surface of the turntable 32 is reflected by the inner peripheral end surface C <b> 1 and the inner peripheral end surface of the circular hole in the center of the glass substrate W. Since it can pass through the inside of C1 in the radial direction, the light and darkness of the light at the inner peripheral end face C1 measured by the light receiving unit 11 is clear, and the inner peripheral end face C1 can be accurately measured.

  FIG. 6 is a perspective view showing a second specific example of the rotation mechanism 10. The notch portion formed in the central shaft 33 is not limited to the groove shape as shown in FIG. 4, and the inner periphery of the glass substrate W in a state where the glass substrate W is stationary as shown in FIG. 6. The shape may be such that a part of the end surface C1 does not contact the side surface 33a of the central shaft 33.

  Further, the turntable 32 and the central axis 33 are dark (typically black) so that the light irradiated from the light projecting unit 12 is not irregularly reflected and further, the light received by the light receiving unit 11 is not irregularly reflected. It is preferable that

  FIG. 7 is a schematic view showing a third specific example of the rotation mechanism 10. The rotating mechanism 10 may rotate the glass substrate W in the circumferential direction by a rotating roller that can circumscribe the outer peripheral end surface C2 of the glass substrate W. FIG. 7 shows rotating rollers 41 to 43. All of the rotating rollers may be provided with a driving source that applies a rotational force to the glass substrate W, or only a part thereof is provided with such a driving source, and the rest is provided with such a driving source without being provided with such a driving source. It may function as.

  FIG. 8 is a view for explaining an apparatus for measuring the center deviation of the plurality of glass substrates W accommodated in the cassette 40 by using the rotation mechanism 10 shown in FIG. In FIG. 3 described above, the configuration in which the light irradiation direction from the light projecting unit 12 to the light receiving unit 11 is the vertical direction is illustrated. FIG. 8 illustrates a configuration in which the light irradiation direction from the light projecting unit 12 to the light receiving unit 11 is the horizontal direction. In FIG. 8, the light projecting unit 12, the light receiving unit 11, the calculation unit 16, the output unit 17, and the like illustrated in FIG.

  FIG. 8 is a view of the cassette 40 as viewed from above. The cassette 40 is a storage container that can accommodate a plurality of glass substrates W arranged side by side in a lateral direction (that is, a normal direction of the main plane S) in a state where their main planes S are vertical. (As a specific example, a rack). The cassette 40 supports a plurality of glass substrates W with their upper and lower portions opened and exposed. The rotating rollers 41 and 42 are provided as an elevating mechanism that can push up one glass substrate W from below to a specified position and lower the glass substrate W pushed up to the specified position again. The rotating rollers 41 and 42 are disposed below the cassette 40 in the initial state before being pushed up. At the specified position, the rotating roller 43 shown in FIG. 7 provided with a driving source for applying a rotational force in the circumferential direction to the glass substrate W is installed (not shown in FIG. 8). The cassette 40 is placed on a carrier 44 that allows the cassette 40 to move in the lateral direction.

  FIG. 9 is a view for explaining a method of measuring the center deviation of the plurality of glass substrates W accommodated in the cassette 40. FIG. 9 is a view of the cassette 40 as viewed from the side. (A) As shown in (b), when a measurement start switch (not shown) is pressed, the rotating rollers 41 and 42 are raised. The rotating rollers 41 and 42 lift the glass substrate W1 while standing and detach it from the storage container 40 while supporting the outer peripheral end surface of the lower portion of the glass substrate W1. As shown in (c), the rotating rollers 41 and 42 raise the glass substrate W <b> 1 until the outer peripheral end surface of the upper portion of the glass substrate W <b> 1 contacts the rotating roller 43. When the outer peripheral end surface of the upper portion of the glass substrate W1 comes into contact with the rotating roller 43, the rotating roller 43 rotates the glass substrate W1 in the circumferential direction by the driving force of the motor M. The light receiving unit 11 (not shown) measures the radial width B of the main plane S of the glass substrate W1 over the entire circumference, as described above. As shown in (d), after measuring the radial width B for the entire circumference, the rotating rollers 41 and 42 are lowered while the glass substrate W1 is standing and returned to the original storage position of the storage container 40. As shown in (e), the cassette 40 is separated by one pitch (so that the glass substrate W2 accommodated next to the accommodation position of the glass substrate W1 can be lifted and removed from the storage container 40 by the rotating rollers 41, 42. Move by the length of the storage interval). A carrier 44 and a controller 45 that controls the movement of the carrier 44 in the lateral direction are provided as a pitch movement mechanism that moves the relative position of the cassette 40 and the rotating rollers 41 and 42 in the lateral direction. As shown in (f), the rotating rollers 41 and 42 raise the glass substrate W2 while standing and support it from the storage container 40 while supporting the outer peripheral end surface of the lower portion of the glass substrate W2. Thereafter, the same is repeated.

  The calculator 16 (not shown) calculates the difference A between the maximum value Bmax and the minimum value Bmin of the measured radial width B for each of the plurality of glass substrates W. Thereby, the center shift | offset | difference for every several glass substrate W is measurable. The calculation of the difference A may be performed every time the measurement of the radial width B for the entire circumference of one glass substrate W is completed, or the entire circumference of the plurality of glass substrates W accommodated in the cassette 40. The measurement in the radial direction width B may be performed collectively at the stage when all the measurements are completed.

  Thus, according to the above-described embodiment, in order to measure the center deviation between the inner circumference and the outer circumference of the glass substrate W, it is not necessary to obtain the centers of the inner circumference and the outer circumference, respectively. It can be measured easily in a short time (when the roundness of the inner circumference and the roundness of the outer circumference are sufficiently smaller than the center deviation values to be measured, respectively). Further, the rotation center of the glass substrate W and the rotation center of the rotation mechanism 10 do not have to coincide with each other, and it is not necessary to perform centering in advance, so that the measurement time can be shortened. As a result of shortening the measurement time, the productivity of the glass substrate is also improved.

  In order to confirm the effect of shortening the measurement time, a conventional stylus type concentricity measuring device (manufacturer: KOSAKA, device name: Roncorder EC1550) and the non-contact type measuring device shown in FIG. 3 as an embodiment of the present invention The measurement tact time was compared with the time required for measurement alone. In the case of the conventional stylus type concentricity measuring device, the measurement tact time is about 3 minutes and the time required for only the measurement is about 1 minute 20 seconds, whereas the non-contact type measurement device shown in FIG. In this case, the measurement tact time was about 11 seconds, and the time required for the measurement was about 7 seconds, and a significant time shortening effect was confirmed.

  Moreover, according to the apparatus or method illustrated in FIGS. 8 and 9 as an embodiment of the center deviation measuring apparatus and method of the present invention, the center deviations of a plurality of glass substrates W can be measured in a short time. In particular, in the mass production process, since a plurality of glass substrates W are often handled in a state where they are placed on the cassette 40, the effect obtained by reducing the measurement time is particularly high.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications, improvements, and modifications can be made to the above-described embodiments without departing from the scope of the present invention. Substitutions can be added.

  For example, the radial width B of the main plane S can also be measured by the separation distance along the pixel row on the imaging screen between the inner peripheral end face C1 and the outer peripheral end face C2. A captured image obtained by the image sensor is composed of a plurality of pixels. The position of the subject in the captured image can be represented by the coordinates assigned to each pixel constituting the captured image.

  For example, the measurement area DA shown in FIG. 1A is set as the field of view of the captured image. Assuming that the left-right direction of the captured image is the x-axis direction and the up-down direction is the y-axis direction, the absolute position of the inner peripheral end face C1 is a coordinate representing the positions of pixels to which a plurality of points Pj on the inner peripheral end face C1 belong (xj, yj) (j is a natural number). Similarly, the absolute position of the outer peripheral end face C2 can be determined by coordinates (xi, yi) representing the positions of pixels to which a plurality of points Pi on the outer peripheral end face C2 belong (i is a natural number). Therefore, the arithmetic unit 16 described above can measure the distance (number of pixels) between the point Pj and the point Pi having the same x coordinate as the radial width B. The radial width B over the entire circumference of the main plane S can be measured by moving the inner circumferential end face C1 and the outer circumferential end face C2 over the entire circumference by the rotation mechanism 10 so as to enter the measurement area DA.

  Moreover, in the above-mentioned Example, the rotation mechanism 10 was illustrated as a movable means which passes the main plane S to measurement area | region DA over a perimeter. In this embodiment, the glass substrate W in the measurement area DA is moved by rotating the rotation mechanism 10 while fixing the measurement unit such as the light receiving unit 11. However, the movable means may cause the main plane S to pass through the measurement area DA over the entire circumference by moving a measurement unit such as the light receiving unit 11.

  In the embodiment shown in FIGS. 8 and 9 described above, the movement of the rotating rollers 41 to 43 in the lateral direction is fixed, the cassette 40 is moved in the lateral direction, and the rotation rollers 41 to 43 and the cassette 40 are moved. The relative position in the horizontal direction was changed. However, the relative position of the rotating rollers 41 to 43 and the cassette 40 in the horizontal direction may be changed by moving the rotating rollers 41 to 43 in the horizontal direction and fixing the movement of the cassette 40 in the horizontal direction. .

  There is no restriction | limiting in particular as a glass substrate used as the measuring object of this invention, What is necessary is just a disk-shaped board | substrate which has a circular hole in the center part.

  In addition, the glass type of the glass substrate is appropriately selected for each application, but may be amorphous glass or crystallized glass, and tempered glass having a tempered layer on the surface layer of the glass substrate (for example, Chemically tempered glass) may also be used.

  Moreover, there is no restriction | limiting in particular as a manufacturing method of the glass substrate before a process (henceforth a glass base substrate), The thing produced by the float process may be used, The thing produced by the fusion method may be used, It may be made.

  Among disk-shaped substrates with a circular hole in the center, the glass substrate for magnetic recording media is required to have a level that is stricter than the shape characteristics required for other glass substrate products. The manufacturing method of the glass substrate for magnetic recording media including the inspection process having the measuring method used and the measuring method using this measuring apparatus is most suitably applied.

  Generally, the manufacturing process of the glass substrate for magnetic recording media and the magnetic disk includes the following processes. (1) A glass base substrate formed by a float method, a fusion method or a press molding method is processed into a disk shape having a circular hole in the center, and then chamfered on the inner peripheral side surface and the outer peripheral side surface. (2) Grinding is performed on the upper and lower main planes of the glass substrate. (3) End face polishing is performed on the side surface portion and the chamfered portion of the glass substrate. (4) Polish the upper and lower main planes of the glass substrate. The polishing step may be only primary polishing, primary polishing and secondary polishing may be performed, or tertiary polishing may be performed after secondary polishing. (5) A glass substrate for a magnetic recording medium is manufactured by precision cleaning of the glass substrate. (6) A thin film such as a magnetic layer is formed on a glass substrate for a magnetic recording medium to manufacture a magnetic disk.

  In the manufacturing process of the glass substrate for magnetic recording medium and the magnetic disk, glass substrate cleaning (inter-process cleaning) or etching of the glass substrate surface (inter-process etching) may be performed between the processes. Furthermore, when high mechanical strength is required for the glass substrate for magnetic recording media, a strengthening step (for example, a chemical strengthening step) for forming a reinforcing layer on the surface layer of the glass substrate is performed before the polishing step, after the polishing step, or the polishing step. You may carry out between.

  In the present invention, the glass substrate for a magnetic recording medium may be amorphous glass, crystallized glass, or tempered glass (for example, chemically tempered glass) having a tempered layer on the surface layer of the glass substrate. Further, the glass base substrate of the glass substrate of the present invention may be made by a float method, may be made by a fusion method, or may be made by a press molding method.

  If the measurement apparatus of the present invention satisfies the measurement standard, the magnetic recording medium during processing in the glass substrate shape imparting step (1) and the end surface polishing step (3) in the manufacturing process of the glass substrate for magnetic recording media and the magnetic disk. It can be used for inspection of the shape of a glass substrate for media. Further, in the manufacturing process of the glass substrate for magnetic recording medium and the magnetic disk, if the measurement standard is satisfied, the shape inspection of the glass substrate for magnetic recording medium (5) manufactured by precisely cleaning the glass substrate (glass for magnetic recording medium) It can be used for final inspection of a substrate) and shape inspection of a magnetic disk (6) manufactured by forming a thin film such as a magnetic layer on a glass substrate for a magnetic recording medium.

DESCRIPTION OF SYMBOLS 1 Center deviation measuring apparatus 10 Rotating mechanism 11 Light receiving part 12 Light projecting part 13 Light receiving surface 14 Light projecting surface 15 Strut 16 Calculation part 17 Output part 18 Base 21 Light source 22 Lens 23 Telecentric lens 24 Beam splitter 25 CCD image sensor 26 CMOS image sensor 31 Housing 32 Turntable 33 Central Axis 40 Cassette 41-43 Rotating Roller 44 Carrier 45 Control Unit A Difference B Radial Width C1 Inner End Face C2 Outer End Face DA Measurement Range S Main Plane W Glass Substrate

Claims (16)

A center deviation measuring device for measuring the center deviation between the inner circumference and the outer circumference of a disc-shaped substrate having a circular hole in the center,
A measurement unit that measures the radial width of the main plane sandwiched between the inner periphery and the outer periphery over the entire circumference of the disk-shaped substrate;
A calculation unit that calculates a difference between the maximum value and the minimum value of the radial width measured by the measurement unit and calculates a center shift using the difference;
A center deviation measuring apparatus comprising: A movable mechanism,
The measurement unit measures an object to be measured in a predetermined measurement area,
The center shift measuring apparatus according to claim 1, wherein the movable mechanism passes the main plane through the measurement region over the entire circumference of the disk-shaped substrate.   The center deviation measuring apparatus according to claim 2, wherein the movable mechanism includes a rotation mechanism that rotates the disk-shaped substrate in a circumferential direction of the disk-shaped substrate. The measurement unit has a light receiving unit that receives light coming from the direction of the main plane of the disk-shaped substrate,
The center deviation measuring device according to claim 2 or 3, wherein the radial width is measured based on light received by the light receiving unit.   The center deviation measuring apparatus according to claim 4, wherein the measuring unit includes a light projecting unit that irradiates light to the disk-shaped substrate.   The center deviation measuring device according to claim 4 or 5, wherein the light receiving unit receives light arriving from the direction of the main plane with an imaging device.   The center deviation measuring device according to any one of claims 4 to 6, wherein a light receiving surface of the light receiving unit faces downward. The movable mechanism is
Disc shape in which a plurality of disc-shaped substrates having a circular hole in the central portion are stowed up and separated from a storage container that is stored side by side in a standing state, and the disc-shaped substrate that is contained is raised in a standing state. An elevating mechanism for lowering the substrate and returning it to the storage container;
Pitch movement for moving the horizontal relative position of the storage container and the lifting mechanism so that another disk-shaped substrate stored in the storage container is lifted and removed from the storage container by the lifting mechanism The center deviation measuring device according to any one of claims 2 to 6, further comprising a mechanism.   The center deviation measuring device according to any one of claims 1 to 8, wherein the disk-shaped substrate is a glass substrate.   The center deviation measuring apparatus according to claim 9, wherein the glass substrate is a glass substrate for a magnetic recording medium. A center deviation measuring method for measuring the center deviation of the inner circumference and outer circumference of a disc-shaped substrate having a circular hole in the center,
A measuring step of measuring the radial width of the main plane sandwiched between the inner periphery and the outer periphery over the entire circumference of the disc-shaped substrate;
A calculation step of calculating a difference between the maximum value and the minimum value of the measured radial width;
A method of measuring a center deviation. A center deviation measuring method for measuring the center deviation of the inner circumference and outer circumference of a disc-shaped substrate having a circular hole in the center,
From the storage container that stores a plurality of disk-shaped substrates having a circular hole in the center in a standing state, the stored disk-shaped substrates are lifted and detached in a standing state by an elevating mechanism,
Rotate the detached disk-shaped substrate in the circumferential direction of the disk-shaped substrate,
A measurement process for measuring the radial width of the main plane of the rotated disk-shaped substrate over the entire circumference;
The disk-shaped substrate whose radial width is measured is lowered by the lifting mechanism and returned to the storage container,
Pitch movement for moving the horizontal relative position of the storage container and the lifting mechanism so that another disk-shaped substrate stored in the storage container is lifted and removed from the storage container by the lifting mechanism Process,
A center deviation measuring method comprising: calculating a difference between a maximum value and a minimum value of the radial width measured in the measurement step and calculating a center deviation using the difference.   The center deviation measuring method according to claim 11 or 12, wherein the disk-shaped substrate is a glass substrate.   The center deviation measuring method according to claim 13, wherein the glass substrate is a glass substrate for a magnetic recording medium.   The manufacturing method of the disk shaped board | substrate which has an test | inspection process using the center shift measuring apparatus as described in any one of Claims 1-10.   The manufacturing method of a disk shaped board | substrate including the test | inspection process in which the center-shift measuring method as described in any one of Claims 11-14 is used.

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