JPH10320838A - Method and apparatus for measuring disk warpage, method and apparatus for displaying warpage, continuous manufacturing method for disk, and method for measuring disk thickness - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for measuring the amount of disk warpage based on disk warpage angle data. A laser beam is radiated along a spiral scanning line from the inner peripheral side to the outer peripheral side of the surface of a magneto-optical disk or digital video disk, and specular reflection of a reflected laser beam at a plurality of measurement points on the scanning line. The warp angle of each measurement point is determined based on the amount of displacement from the position, and the warp amount for the corresponding measurement point in each round after the round is determined based on the one round of the inner circumferential measurement point on the scanning line. A method for measuring the amount of warpage of a disk, which is obtained based on an angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magneto-optical disk,
The present invention relates to measurement of the amount of warpage of a digital video (or versatile) disk and display of warpage.

[0002]

2. Description of the Related Art Conventionally, as a method of measuring a warp angle and a warp shape of a disk having a light reflecting surface such as a magneto-optical disk and a digital video disk, for example, a laser beam is applied to a surface to be measured, Is known which measures the amount of displacement of an object by a position detecting means.

Conventionally, the amount of displacement from a regular reflection position when a laser beam from a light source hits a surface to be inspected perpendicularly and is reflected has been measured by a position detecting means, and the amount of displacement and the geometrical distance between a reflection point and a light receiving point have been measured. A method of calculating and calculating the warp angle from the relationship with the target distance has been adopted.

Hereinafter, a method for measuring a warp angle according to the prior art will be described with reference to the drawings. FIG. 7 shows a state in which the disk to be measured has no mechanical deformation such as warpage or distortion, that is, a state in which the laser beam 5 is irradiated perpendicularly to the irradiation surface of the disk and is specularly reflected. Things. In FIG. 7, reference numeral 1 denotes a laser beam irradiating unit, 2 denotes a beam splitter, 3 denotes a disk as an object to be measured, and 4 denotes a position detecting unit. The distance between the reflection surface of the beam splitter 2 and the position detecting means 4 is LA, and the distance between the reflection surface of the beam splitter 2 and the irradiation surface of the disk 3 is LB.

FIG. 8 shows a case where the irradiation surface of the laser beam 5 of the disk 3 is inclined by θ with respect to a reference surface (a surface assumed to be irradiated vertically by the laser beam 5 and indicated by a dotted line). ing. Is based on mechanical deformation such as warpage or distortion of the disk 3. From simple geometric considerations, when the tilt of the disk is θ relative to the reference plane, the laser beam 5 reflects off the reference plane by an angle equal to twice θ.

The reflected laser beam 5 has its course changed by about 90 degrees by the beam splitter 2 and is irradiated on the light receiving surface of the position detecting means 4. When the position irradiated with the reflected beam is displaced from the regular reflection position, the position detecting means 4 outputs a voltage having a value proportional to the amount of displacement.

When the displacement X of the reflected laser beam based on the output voltage of the position detecting means 4 is obtained, the inclination (warp) angle of the irradiation surface is generally defined as 2θ, and is obtained by the following equation.

[0008]

[Equation 1] 2θ = arctan {X / (L A + L B)} --- (1) formula

Generally, this 2θ is measured over the entire surface of the disk, and the maximum value is defined as the warpage angle. θ represents the angle at which the disk is actually warped with respect to the reference plane. In the equation (1), when 2θ is expressed in rad units and (L _A + L _B ) ≫X can be assumed, simply 2θ
_{= X / (L A + L} B) no practical problem even.

In order to measure the warp angle 2θ over the entire area of the disk 3, the relative positional relationship between the laser beam irradiation means 1 and the position detection means 4 shown in FIG. The beam 5 may be relatively moved so that the irradiation position coincides with the radial direction of the disk 3, and the output from the position detection means 4 appearing at this time may be sequentially read or recorded.

In the method of relative movement, for example, the entire surface of the disk can be scanned by fixing the laser beam irradiation means and the position detection means and providing a mechanism for moving the disk in the horizontal direction while rotating the disk. Alternatively, on the contrary, it is also possible to scan while moving the laser beam irradiating means and the position detecting means in the radial direction of the disk while simply rotating the disk while fixing it at one point. On the other hand, as another method, there is a method of measuring the warpage of the disk based on the capacitance, but in this method, the measurement is performed so as to accurately trace the groove included in the light reflective recording layer. Therefore, there is a disadvantage that it takes a very long time. This disadvantage is particularly remarkable when performing continuous production and performing in-line inspection, particularly when performing 100% inspection.

In order to display the results obtained in this way, for example, the horizontal axis is used as a time axis, and the output voltage from the position detecting means 4 is simply displayed in a time-varying manner. A warp angle is calculated from a dimensional constant determined by a geometrical arrangement with the position detecting means 4, and an amount representing the position of the disk on the horizontal axis, for example, an amount representing an angle or a position in the circumferential direction, and a warp angle on the vertical axis. Is used to represent the data.

[0013]

However, even in these methods, from the measurement results, it is possible to intuitively determine what shape the disk actually has and what portion is distorted in what direction. There was a problem that it was difficult to grasp. This is presumed to be due to the fact that the physical quantity obtained by the measurement is an abstract quantity called “angle” and that it is merely a list of point data on the disk surface.

In view of such circumstances, the present invention provides a method and an apparatus for measuring the amount of warpage of a disk based on the warp angle data of the disk, and a method and apparatus for approximately determining a three-dimensional shape by numerical calculation and displaying the same. To provide Another object of the present invention is to provide a method for manufacturing a disk by such a method and a method for measuring the thickness of a disk to which a method for measuring warpage is applied.

[0015]

DISCLOSURE OF THE INVENTION In the currently manufactured disk, the distortion and deformation are almost always increased toward the outer periphery of the disk and relatively small at the inner periphery. In particular, the disk manufacturing technology itself has been improved year by year. This tendency is remarkable because the absolute value of the deformation itself has become smaller. The inventor pays attention to this point, and calculates the amount of warpage of a position located on the outer peripheral side from the reference position based on the inner peripheral side of the disc based on the warp angle of the position, and performs such processing. It has been found that the amount of warpage and the shape of the disk can be obtained by performing the method at many points on the disk surface.

That is, according to the present invention, a laser beam is irradiated along a spiral scanning line from the inner peripheral side to the outer peripheral side of the surface of a magneto-optical disk or digital video disk, and reflected laser beams at a plurality of measurement points on the scanning line. The warp angle of each measurement point is determined based on the amount of displacement of the beam (reflection from the information recording layer of the disk) from the regular reflection position, and the measurement is performed on the scanning line with reference to one measurement point on the inner circumference side. The amount of warpage at a corresponding measurement point in each revolution of the disk is determined based on the warpage angle.

It is most preferable that the first round on the inner peripheral side serving as a reference of the amount of warp be the first round of the scanning line, but it may be the second round or later depending on the state of the warp amount. it can. When the first round is used as a reference, the plane including the starting point of the scanning line and a plane orthogonal to the irradiated laser beam are used as a reference plane, and the measurement point of the first round of the scanning line is on the reference plane. Assuming that n
= 1, 2, 3,... N) The amount of warpage of each measurement point on the spiral scanning line in the (n + 1) th round is sequentially obtained based on the warp angle with reference to the round, and the amount of warpage is determined by the same method for the disk. The sum from the inner peripheral side on the line is used as the amount of warpage from the reference plane.

In the method of measuring the amount of warpage of a disk according to the present invention, the more the number of measurement points, the more precisely the amount of warpage can be measured, but the time required for the measurement increases.
Therefore, it is desirable to set the number of revolutions of the scanning line of the laser beam and the number of a plurality of measurement points in the scanning line as small as possible within a range in which the degree of the warpage of the disk can be visualized three-dimensionally on the two-dimensional coordinate axis plane.

More specifically, it is desirable that the laser beam has a moving pitch of 0.5 to 3 mm per revolution of the scanning line and that the number of measurement points in each revolution of the scanning line is 50 to 300. If the movement pitch is less than 0.5 mm, the number of laps becomes too large and the measurement time becomes longer, while 3 m
If it exceeds m, the number of turns is too small, and it is difficult to display a warped shape similar to an actual disk. If the number of measurement points in each round is less than 50, it is difficult to display a warped shape similar to an actual disk because the number of measurement points is small. On the other hand, if the number of measurement points exceeds 300, the number of measurement points becomes too large and the measurement time becomes longer. become longer.

In order to spirally scan the surface of the disk with the laser beam, the irradiation position of the laser beam is relatively moved in the radial direction from the inner peripheral side to the outer peripheral side of the disk surface while rotating the disk. do it. More specifically, (1) moving the laser beam irradiation position in the radial direction from the inner peripheral side to the outer peripheral side of the disk while fixing the rotational position of the disk, or (2) applying the laser beam The disk may be moved so that the irradiation position of the laser beam moves in the radial direction from the inner peripheral side to the outer peripheral side of the disk while fixing the position of the source.

At this time, the rotation speed of the disk is 550 to 1600 r, which is the same as the rotation speed at which the disk is actually used.
pm. The storage area of the digital video disc has a radius of r = 23 to 58 mm, and the peripheral speed during reproduction is 3.5 m / s and 3.8 m / sec.
Is adopted, so that the maximum rotation speed Nmax and the minimum rotation speed Nmin
Are Nmax = 3.8 / (2 × 23 × 10 ⁻³ ) × 60 = 1578 rpm and Nmin = 3.5 / (2 × 58 × 10 ⁻³ ) × 60 = 576 rpm, respectively. The time for moving the irradiation position of the laser beam in the radial direction from the inner peripheral side to the outer peripheral side of the disk is 0.
It is desirable to set it to 5 to 3 seconds. If the time is less than 0.5 seconds, the moving time is too fast, and it is difficult to perform an appropriate measurement. On the other hand, if the time exceeds 3 seconds, there is a possibility that a delay in manufacturing tact may be caused when this measuring method is incorporated in a disk manufacturing process.

In the present invention, a laminated disk having a recording layer on both sides is used as a magneto-optical disk or a digital video disk. It is also possible to measure the amount of warpage on both sides. According to this method, only one laser beam is used to measure only one surface of the disk, and then the disk is turned upside down to measure the other surface, thereby sequentially measuring the warpage of the front and back surfaces. Although there is a method, it is preferable to provide one laser beam on each side of the disk and measure both the front and back surfaces simultaneously. Note that this is the same not only for the measurement of the amount of warpage but also for the other methods described later.

If the measurement points are continuously connected along the scanning line based on the displacement amount from the reference plane at each measurement point, the state of the warp can be displayed three-dimensionally on a two-dimensional coordinate axis plane. it can. The display of the warpage is not only on one side of the disk, but also as a magneto-optical disk or digital video disk, using a bonded type disk having a recording layer on both front and back sides, and irradiating a laser beam on both the front and back surfaces. If the amount of warpage on both sides is obtained, the warpage on both sides can be displayed.

The method for measuring the amount of warpage of the present invention can be carried out independently, but can also be incorporated in the manufacturing process of a magneto-optical disk or a digital video disk. Specifically, (1) a step of continuously manufacturing a magneto-optical disk or a digital video disk, and (2) a spiral scanning line extending from the inner peripheral side to the outer peripheral side of the surface of the magneto-optical disk or digital video disk. And irradiating a laser beam at each of the plurality of measurement points on the scan line to determine the warp angle of each measurement point based on the amount of displacement of the reflected laser beam from the specular reflection position. A step of measuring the amount of warpage for a corresponding measurement point in each of the laps after the lap based on the point, based on the warp angle; and (3) excluding the disk when the warp angle exceeds a specified angle. (4) If necessary, continuously connect measurement points along the scanning line based on the amount of displacement of each measurement point from the reference plane. Step of displaying three-dimensionally displayed on the original coordinate plane, continuous process of the magneto-optical disc or digital video disc, characterized in that it consists of capital is provided. A process for continuously manufacturing a magneto-optical disk or a digital video disk may be in accordance with a known method.

If the maximum value of the warpage angles of all the measurement points on the light reflecting surface of the disk to be inspected is greater than or equal to a specified angle, it can be determined that the disk is rejected. In the case of a digital video disk, a disk having a warp angle in the radial direction of the disk of 0.8 ° or more is generally rejected according to the standard. When higher quality is required, the case where the warp angle in the disk radial direction ≧ 0.3 ° can be further excluded as a rejected product. Of course, in rejecting the rejected product, not only the warpage angle but also the warpage amount may be used. Also in the above manufacturing method, as a magneto-optical disk or digital video disk, a bonded magneto-optical disk or digital video disk having a recording layer on both front and back surfaces is used, and both surfaces of the front and rear surfaces are irradiated with a laser beam. Then, the amount of warpage of the front and back surfaces of the disk can be measured, and if necessary, the warpage of the front and back surfaces of the disk can be displayed.

The method for measuring the amount of warpage of a disk according to the present invention is as follows.
A displacement meter having laser beam irradiation means for irradiating a laser beam onto the surface of a magneto-optical disc or digital video disc and position detection means for detecting the displacement of the reflected light of the laser beam from the regular reflection position; Means, and a moving means for relatively moving the displacement meter and the disc rotating means in the radial direction of the disc, and irradiating a laser beam in a spiral form from the inner peripheral side of the surface of the disc, The measurement can be performed by a disk warpage amount measuring device that measures the displacement amount for a corresponding measurement point in each of the subsequent rounds based on a plurality of measurement points in one round on the inner circumference side of the scan line.

In the present invention, a magneto-optical disk or a digital video disk can be obtained by bonding two disks by curing and bonding by ultraviolet irradiation using an ultraviolet-curable compound, further,
The ultraviolet irradiation may be performed by flashing from at least one surface of the disk. According to the flash irradiation,
This is because the UV curing of the adhesive can be performed with the power consumption suppressed as compared with the continuous irradiation, in other words, the total irradiation light amount required for curing the ultraviolet curable compound by the continuous irradiation is also small. . Therefore, according to the ultraviolet irradiation, the adhesive curing treatment per unit time is greatly improved.
Further, the degree of warpage can be further reduced as compared with the case of continuous irradiation with increased power consumption.

As a quality control item of a digital video disk, there is a thickness of an adhesive layer for bonding two disk substrates in addition to the above-mentioned warpage. If the thickness of the adhesive layer fluctuates, the thickness of the entire disc also fluctuates. If the value exceeds a specified range, the characteristics of the disc are impaired. However, since the adhesive layer is sandwiched between the two disk substrates, it cannot be directly contacted, and the measurement is not easy. For example, it is difficult to measure the thickness of the adhesive layer of a disk having a size of only several tens of microns by an ultrasonic inspection method known as a nondestructive inspection method. Even if possible, the inspection apparatus would be very expensive and the measurement time would be on the order of minutes, which is not practical. Further, a laser focus displacement meter known as another non-destructive inspection device cannot be applied because the object needs to be a transparent body.

The thickness of the adhesive between the disk substrates can be measured by applying the above-described method of measuring the amount of warpage of the disk. That is, a laser beam is applied to the front and back surfaces of a magneto-optical disk or a digital video disk from the inner peripheral side of the disk along a spiral scanning line, and the amount of displacement of the reflected laser beam from the regular reflection position is determined, and the scanning is performed. The plane including the starting point of the line and orthogonal to the laser beam to be irradiated is defined as reference planes Z1 and Z2, and the range of the first round of the scanning line is assumed to be on the reference plane.
(Where n = 1, 2, 3,... N) The amount of warpage on the spiral scanning line in the (n + 1) th round is sequentially determined based on the amount of displacement based on the number of rounds, and the amount of warpage on the same normal line of the disk. _Are added from the inner peripheral side to obtain the disk warpage amounts T _Z1 and T _Z2 with respect to the reference surfaces Z 1 and Z 2 set for the front and back surfaces, and then | T _Z1 −T _Z2 | for the warp amounts T _Z1 and T _Z2. If executed, the thickness between the light reflecting surfaces can be known. If the adhesive layer exists between the light reflecting surfaces, that is, between the recording layers, the thickness of the adhesive layer can be measured.

The above-described method for measuring the thickness of a disc is based on the disc having a light reflecting surface formed on the front and back outermost surfaces, and a layer made of a light-transmitting material formed on the front and back outermost surfaces. Both disks having a laminated structure in which a layer made of a reflective material is formed can be measured. The former disk includes a disk composed of a single light-reflective material, and a laminated structure in which a surface layer composed of a light-reflective material is formed on the front and rear outermost surfaces and an intermediate layer composed of another material is provided between the layers. There are two types of discs.

In the above-described method for measuring the thickness of the disk, the distance between the light reflecting surfaces can be measured as the thickness of the disk. In a disc having a laminated structure formed and having an intermediate layer made of another material between the layers, the thickness of the intermediate layer can also be measured. Measuring the thickness of the adhesive layer of a digital video disc is one such aspect.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on its embodiments. <Method of Measuring Warpage> A laser beam spot is irradiated along a spiral scanning line virtually drawn on a disk as shown in FIG. It is preferable that this scanning line does not trace the recording group included in the light reflection surface as it is, and the spiral scanning line is provided so as to be larger than the width (pitch) of the interval between the actual groups. Is preferred. At this time, the number of data extracted per one rotation of the disk is I, and the distance (hereinafter referred to as a movement pitch) by which the laser beam spot moves in the disk radial direction per one rotation of the disk is p.

From the inner peripheral side of the spiral scanning line,
.., And the scanning line corresponding to the outermost periphery is denoted by N. The starting point of the spiral scanning line 1, that is, n =
1, information extraction is started from the point of i = 1, and the end point of the spiral scanning line 1 is the start point of the spiral scanning line 2. Information extraction is performed at equal intervals for each round. The interval between adjacent spiral scanning lines corresponds to the movement pitch p.

The method for determining the amount of warpage of the disk based on the extracted information is as follows. That is, it is assumed that the amount of warpage at the position of the spiral scanning line 1 is neglected for the sake of convenience, and that the area inside the scanning line 1 is flat, that is, the amount of warpage is zero. Then, a plane including the starting point of the scanning line 1 and orthogonal to the laser beam to be irradiated is set as a reference plane for the amount of warpage.
As described above, the above assumption hardly matters in practical use. Note that the upward warpage amount with respect to the reference plane is a positive value, and the downward warpage amount is a negative value.

At the i-th position on the spiral scanning line n
The displacement of the reflected laser beam _ni(However, n = 1,
2, ..., N and i = 1,2, ..., I)
Then X_1i, X_2i, ..., X_ni,X_NiIs almost the same law
It can be regarded as data extracted on the line. Soshi
As described above, the amount of warpage on the spiral scanning line 1 is convenient.
Ignore the above and plan the area inside the spiral scanning line 1
, The counter at the position of i on the spiral scanning line 2
Amount (for convenience, S_2iX) as shown in FIG.
_1iIs linearly approximated using the following.

[0036]

[Equation 2] S _2i = p × tanθ _2i --- (2)

[0037]

[Equation 3] θ _2i = (1/2) × arctan {X _2i / (L _A + L _B )} −−− (3)

More generally, when the suffix 2 in the above equation is changed to n, an arbitrary i on an arbitrary spiral scanning line n is obtained.
The displacement X _ni of the reflected laser beam extracted at the th position
Represents the warpage amount S _ni at the i-th position on the next adjacent spiral scanning line n + 1 based on the position.

The information extracted and the start position of the inner circumference side of the disc, for example, a position where the data X ₁₁ is extracted, the incident beam perpendicular to the plane as a reference plane Z, any spiral scan line The amount of warpage T _ni from the reference plane Z at the position (1) can be obtained by the following equation which is added from the inner circumference side of the disk.

[0040]

(Equation 4)

Although the method for determining the amount of warpage on one surface of the disk has been described above, the amount of warpage on the front and back surfaces can also be determined simultaneously by irradiating the laser beam to both the front and back surfaces of the disk at the same time.

<Warp Display Method> The following processing is performed to display the warp shape of the disk. That is, the spiral scanning line drawn on the reference plane by the laser beam is displayed in a substantially elliptical shape. At this time, the distance T _ni from each reference point at each measurement point is represented by the y component of the substantially elliptical equation. Add together. That is, it can be expressed by the following equation.

[0043]

[Equation 5] _{x ni = (a + np +} 360pi / I) × sin (360i / I) --- (5) formula _{y ni = κT ni + (b} + np + 360pi / I) × cos (360i / I)

The coordinates (x _ni , y _ni ) obtained by the above equation are
By successively connecting the discs sequentially, the warped shape of the disc can be visualized and displayed three-dimensionally on a two-dimensional coordinate plane. The coordinates (x _ni , y _ni )
First, for n = 1, i is changed from 1 to I and successively tied. Then, as n = 2, i is similarly connected from 1 to I. Such an operation is performed until n = N.

In the equation (5), a and b are the major axis and the minor axis for representing the spiral scanning line 1 (the innermost circumference) in a substantially elliptical shape, T _ni is the value obtained by the equation (4), p Is the moving pitch,
I represents the number of data extracted per rotation of the disk. The value of I is determined by the required measurement accuracy, but if the value of I is small, the coordinates (x
_ni , y _ni ) is not smooth, and the ellipse becomes uneven, so that at least I ≧
Desirably, it is 50.

Κ is a coefficient for adjusting the sensitivity or the degree of enhancement when the warped shape is visualized and displayed three-dimensionally (hereinafter κ is simply referred to as an enhancement coefficient). Even the slightest warp is expressed as if there is a large warp in the expression.

<Thickness Measuring Method> Next, one of the thickness measuring methods for obtaining the thickness of the intermediate layer of the disk based on the obtained warpage amount will be described.
An example will be described with reference to FIG. FIG. 3 schematically shows a cross section of a disk in which an intermediate layer 7 made of an adhesive is present between the light reflection layers 6 and 6 made of a recording layer. In comparison, the thickness of the light reflection layer 6 is extremely thin. Either _{one of} the reference surfaces Z ₁ and Z ₂ set for the front and back surfaces of the disk (in this example, the reference surface Z ₁ is used) is set as a common reference surface K, and the disk front surface is used. Is defined as T _K2 (determined by the above-described method of measuring the amount of warpage). Assuming that the amount of warpage of the back surface at the position corresponding to the amount of warpage T _K2 is T _K1 and the thickness of the light reflection layer 6 is constant, the thickness T of the intermediate layer 7 at that position is determined by the following equation.

[0048]

[Equation 6] T = T _K2 −T _K1 −−− (6)

By performing the above-described processing for all pieces of information obtained regarding the amount of warpage, the maximum intermediate layer 7, that is, the thickness Tmax of the adhesive layer in one disc can be obtained. When the Tmax exceeds the prescribed management reference value, the disc may be handled as an NG product.

In the above embodiment, one of the reference surfaces set for the front and back surfaces of the disk is used as the common reference surface. However, the common reference surface is newly provided separately from the reference surfaces set for the front and back surfaces of the disk. Surfaces can also be set. For example, a plane including an intermediate point between the set front and back reference planes can be set as the reference plane.

In the above embodiment, the common reference plane is
The thickness of the intermediate layer 7 is measured by setting
It can also be measured without setting. For example, figure
As shown in Fig. 4, reference planes set for the front and back sides respectively
Warpage amount T based on Z1 and Z2 _Z1, T_Z2, And reference plane Z
1. Distance T between Z2_BUsing the following formula
The thickness of layer 7 can be measured.

[0052]

[Formula 7] T = T _Z2 -T _Z1 + T _B --- (7) Formula

<Embodiment of Measurement Apparatus> FIG. 5 is a view showing an embodiment of the measurement apparatus of the present invention. In this embodiment, a pair of displacement measuring devices D1 and D2 are provided so that the warpage of the front and back surfaces of the disk can be measured. FIG.
In the above, B1 and B2 are laser beam irradiation means. In order to reduce measurement errors, it is desirable that the beam diameter used for laser beam irradiation be as small as possible.
It is desirable to have a mechanism that can adjust the beam diameter at 1.5 mm or less, or at the light receiving position of the reflected beam.

C1 and C2 are position detecting means for receiving the laser beam reflected from the disk A. As this position detecting means, a publicly known position detecting element PSD
(Position Sensitive Device) can be used. There are one-dimensional type and two-dimensional type in PSD,
What is necessary is just to select suitably according to the objective. For example, when determining the warp angle of an arbitrary point only in either the disk radial direction or the disk circumferential direction, the PSD may be a one-dimensional type. In addition, it is also possible to obtain the warp angle in the disk radial direction only with a one-dimensional type, and approximate the warp angle in the disk circumferential direction from the obtained value. However, for simultaneous and / or faster measurements in the radial and circumferential directions of the disk, the two-dimensional type is preferably used. In particular, in the continuous manufacturing process of bonded discs,
When measuring in-line, it is best to use the two-dimensional type. Further, the position detecting means C1, C
2 outputs displacement information of the reflected laser beam.

Laser beam irradiation means B1 and position detection means C1, laser beam irradiation means B2 and position detection means C
Numerals 2 are fixed so that their relative positional relationships do not change, and constitute displacement measurement meters D1 and D2. Moving means E is provided for moving the displacement measurement meters D1 and D2 relative to the disk A in the radial direction of the disk A. As this moving means, a publicly known one-axis electric slider or the like can be used.

F is a rotating means for rotating the disk A, and it is desirable to use an AC servomotor having a small variation in rotation speed. In the present invention, since the warp angle is not measured by tracing the groove, it is not necessary to change the rotation speed of the rotating means of the disk between the inner peripheral side and the outer peripheral side of the measurement point. The rotation speed of the disk during the measurement time of the disk may be always constant. In FIG. 5, the disk is rotated but fixed in the radial direction and only the displacement meter is moved. On the contrary, only the displacement meter is fixed and the disc is fixed. It can be moved in the radial direction while rotating.

G is a rotation position detecting means for detecting the rotation position of the disk A. For example, a shielding piece G1 sufficient to shield light is attached to an axis for rotating the disk, and this is mounted on the shaft. It is possible to apply a method of detecting the passage of the shielding piece G1 and generating a rotation pulse by using a publicly known photointerrupter element G2.

The information recording means H which extracts the reflected laser beam displacement amount information from the position detecting means C1 and C2 and the rotational position information from the rotational position detecting means G at regular time intervals and records them at any time. , An A / D converter and an electronic memory can be used. As a publicly known device having such a mechanism, there is, for example, ADM-652T manufactured by Microscience Inc. which can be used on an ISA bus.

I sets the reference planes Z1 and Z2 on the front and back of the disk based on the reflected laser beam displacement information, and based on the rotational position information and the reflected laser beam displacement information, This is an arithmetic processing means for calculating the warpage amounts T _Z1 and T _Z2 with respect to the reference planes Z1 and Z2. If the display of warp and in the case of thickness measurements, in this processing means I, the formula (5), the above-mentioned | T _{Z1 -} T _Z2 | arithmetic processing or the like can be performed. It should be noted that as the arithmetic processing means, personal computers of almost all known manufacturers and models can be used. Although the display of the warpage can be performed by the arithmetic processing means I, there is a case where a personal computer has insufficient processing capacity to simultaneously perform the above arithmetic processing and display. Is desirably connected as the warp display means J.

The operation of the above measuring device is as follows. That is, while the disk A is being rotated by the rotating means F, the laser beam irradiated on the surface of the disk A from the displacement measurement meters D1 and D2 is relatively moved in the radial direction within the light reflecting surface of the disk A. The change in the amount of displacement of the reflected beam due to the radial warpage of the disk A,
The information is sequentially stored in the information recording unit H in association with the rotation angle of the disk A, and after the scanning of the entire surface of the disk is completed, the stored information is taken out and calculated by the arithmetic processing unit I. .

In the above-described operation, when the rotation speed of the disk and the time interval of information recording are constant, the number of pieces of signal information extracted from the position detecting means C1 and C2 per rotation of the disk is constant. Also, the position detecting means C
For example, if a rotation pulse generated by the above-mentioned publicly known photointerrupter element is used as a timing signal for starting the extraction of information from C2, the displacement amount of the reflected beam can be easily changed to the rotation angle of the disk A. Records can be stored in association with them.

<Example of Display of Warpage> An example of the display of the amount of warpage according to the present invention will be described below. The measurement was performed on a magneto-optical disk having a diameter of 120 mm, and measurement was performed on only one side. The range for measuring the warpage was from the position of 47 mm in diameter on the side where the information recording layer was located to 116 mm in diameter. In the apparatus shown in FIG. 5, the rotation speed of the disk A is kept constant at 12 rotations per second, and the data extraction interval of the position detecting means C1 is set to 833 μs.
c, the moving pitch of the displacement meter D1 is p = 1.08 mm
As a result, the number of data extraction per rotation of the disk was I = 100, and the number of revolutions of the scanning line was 32. Therefore, in the present embodiment, the total number of measurement data to be calculated is 3,200.

Next, FIG. 6 shows a three-dimensionally visualized display of the warped shape of the disk using the method of the present invention. The displacement T _ni from the reference plane is obtained in μm units,
The numerical values were added in equation (5). The scale can be scaled by setting the entire PC screen to 1400 horizontally and 10 vertically.
The image was scaled so as to be 50, and the major axes of the innermost and substantially outermost ellipses were set to 160 and 500, respectively, and similarly, the minor axes were set to 90 and 281 for graphic display.

FIG. 6A shows that when the value of the enhancement coefficient κ is 1,
FIG. 6B shows the case of 3, and FIG. 6C shows the case of 5. The data on which the calculation is based is the same for all of (a) to (c). In the drawing, the position indicated by the arrow represents a point where the amount of warpage from the reference plane is maximum. Numerically, the warpage amount is only about 50 μm even at the maximum point, but it can be seen that the warping state is more clearly expressed as the value of the enhancement coefficient κ increases.

In this display method, the substantially elliptical shape itself changes depending on how the first coordinate scale is determined. Therefore, the value of κ can be said to be relative.

[0066]

As described above, according to the present invention, the amount of warpage can be easily obtained based on the numerical data of the warp angle of the disk, the warp can be displayed, and the thickness of the disk can be reduced. Can be measured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a spiral scanning line of a laser beam.

FIG. 2 is a diagram illustrating a method for obtaining a disk warpage amount in the method of the present invention.

FIG. 3 is a diagram showing an embodiment of a thickness measuring method according to the present invention.

FIG. 4 is a diagram illustrating another example of the thickness detection processing according to the present invention.

FIG. 5 is a block diagram showing one embodiment of the measuring device of the present invention.

FIG. 6 is a diagram showing an example in which a warp of a disk is three-dimensionally visualized and displayed on a two-dimensional coordinate plane according to the method of the present invention.

FIG. 7 is a diagram illustrating an example of a method of measuring a warp angle according to the related art.

FIG. 8 is a diagram showing a state where a reflected laser beam is displaced when a disk to be measured has a warp.

[Explanation of symbols]

 A Disc B1, B2 Laser beam irradiation means C1, C2 Position detecting means D1, D2 Displacement measuring instrument E1, E2 Moving means F Disk rotating means G Rotating position detecting means H Information recording means I Arithmetic processing means J Warp display means

Claims (18)

[Claims] 1. A laser beam is radiated along a spiral scanning line from the inner peripheral side to the outer peripheral side of the surface of a magneto-optical disk or digital video disk, and the reflected laser beam at a plurality of measurement points on the scanning line is corrected. The warp angle of each measurement point is obtained based on the displacement amount from the reflection position, and the warp amount for the corresponding measurement point in each round after the round is determined with reference to the one round inner circumferential measurement point on the scanning line. A method for measuring the amount of warpage of a disk, which is obtained based on the warpage angle. 2. A method including a starting point of the scanning line and a plane orthogonal to a laser beam to be irradiated as a reference plane, and assuming that a measurement point in a first round of the scanning line is on the reference plane, Based on the n-th (n = 1, 2, 3,..., N) cycle, the amount of warpage at each measurement point on the spiral scanning line in the (n + 1) -th cycle is sequentially obtained based on the warp angle, and the warpage is calculated. 2. The method for measuring the amount of warpage of a disk according to claim 1, wherein the amount is added from the inner peripheral side on the same normal line as the amount of warpage from the reference plane. 3. The number of revolutions of a scanning line of a laser beam and the number of a plurality of measurement points on the scanning line are set as small as possible within a range in which the degree of warpage of the disk can be visualized three-dimensionally on a two-dimensional coordinate axis plane. 3. The method for measuring the amount of warpage of a disk according to 1 or 2. 4. A moving pitch of the scanning line for each rotation of 0.5.
The method for measuring the amount of warpage of a disk according to any one of claims 1 to 3, wherein the number of measurement points in each round of the scanning line is 50 to 300 mm. 5. The disk according to claim 1, wherein the irradiation position of the laser beam is relatively moved in the radial direction from the inner peripheral side to the outer peripheral side of the surface of the disk while rotating the disk. Method of measuring the amount of warpage. 6. The disk rotation speed is 550-1600r.
6. The disk according to claim 1, wherein the laser beam irradiation position moves in the radial direction from the inner peripheral side to the outer peripheral side of the disk in a radial direction for 0.5 to 3 seconds. How to measure the amount of warpage. 7. A laminated magneto-optical disc or digital video disc having a recording layer on both sides thereof,
A laser beam is radiated from both the front and back surfaces to measure the amount of warpage of the front and back surfaces of the disc.
7. The method for measuring the amount of warpage of a disk according to any one of 6. 8. A laser beam is irradiated along a spiral scanning line from the inner peripheral side to the outer peripheral side of the surface of the magneto-optical disk or digital video disk, and the reflected laser beam at a plurality of measurement points on the scanning line is corrected. The warp angle of each measurement point is obtained based on the displacement amount from the reflection position, and the warp amount for the corresponding measurement point in each round after the round is determined with reference to the one round inner circumferential measurement point on the scanning line. Displaying the warp three-dimensionally on a two-dimensional coordinate axis plane by continuously connecting measurement points along the scanning line based on the amount of displacement of each of the measurement points from the reference plane, which is obtained based on the warp angle. Characteristic display method of disk warpage. 9. A laminated magneto-optical disk or digital video disk having a recording layer on both front and back surfaces,
9. The method for displaying the warpage of a disk according to claim 8, wherein a laser beam is irradiated from both the front surface and the rear surface. 10. A process for continuously manufacturing a magneto-optical disk or a digital video disk, and (2) a spiral scanning line from the inner peripheral side to the outer peripheral side of the surface of the magneto-optical disk or digital video disk. And irradiating a laser beam at each of the plurality of measurement points on the scan line to determine the warp angle of each measurement point based on the amount of displacement of the reflected laser beam from the specular reflection position. A step of obtaining a warpage amount for a corresponding measurement point in each round after the round based on the point based on the warp angle; and (3) a step of excluding a disk whose warp angle exceeds a specified amount. A continuous manufacturing method of a disk, characterized by comprising: 11. A bonded magneto-optical disk or digital video disk having a recording layer on both front and back surfaces, and a laser beam is irradiated from both the front and back surfaces to measure the amount of warpage of the front and back surfaces of the disk. The method for continuously manufacturing disks according to claim 10. 12. The method according to claim 10, further comprising the step of continuously connecting the measurement points along the scanning line based on the amount of warpage of the measurement points on the disk to display the warp three-dimensionally on a two-dimensional coordinate axis plane. Or the continuous production method of a disk according to 11. 13. The continuous disk manufacturing method according to claim 12, wherein the magneto-optical disk or the digital video disk is obtained by bonding two disk substrates together by bonding with an ultraviolet curable compound which is cured by irradiation with ultraviolet light. 14. The continuous manufacturing method of a disk according to claim 13, wherein the ultraviolet irradiation is performed by flashing from at least one surface of the disk. 15. A displacement amount having a laser beam irradiation means for irradiating a surface of a magneto-optical disk or a digital video disk with a laser beam, and a displacement amount detection means for detecting a displacement amount of reflected light of the laser beam from a regular reflection position. A measuring device, a disk rotating device, and a moving device for relatively moving the displacement measuring device and the disk rotating device in a radial direction of the disk, and a spiral moving from an inner peripheral side to an outer peripheral side of the surface of the disk. A laser beam is radiated along a scanning line, and a warp angle of each measurement point is determined based on a displacement amount of a reflected laser beam from a regular reflection position at a plurality of measurement points on the scanning line, and an inner circumference of the scanning line is determined. The amount of warpage for the corresponding measurement point in each of the subsequent rounds is determined based on the warp angle with reference to the measurement point for one round on the side. An apparatus for measuring the amount of warpage of a disk, which is characterized by: 16. The apparatus for measuring the amount of warpage of a disk according to claim 15, wherein a bonded disk having a recording layer on both front and back surfaces is used, and a displacement meter is provided on both the front and back surfaces. 17. A displacement amount from a regular reflection position of a laser beam reflected by irradiating a laser beam on the front and back surfaces of a magneto-optical disk or a digital video disk from the inner peripheral side of the disk along a spiral scanning line, and calculating the amount of displacement. Planes including the starting point of the scanning line and orthogonal to the laser beam to be irradiated are defined as reference planes Z1 and Z2, and the first round of the scanning line is assumed to be on the reference plane; (However, n = 1, 2, 3,... N).
The amount of warpage on the spiral scanning line in the circumference is sequentially obtained based on the amount of displacement, and the amount of warpage on the same normal line of the disk is added from the inner peripheral side to set a reference plane Z1 set for the front and back surfaces.
A method for measuring the thickness of a disk, comprising: calculating the warpage amounts T _Z1 and T Z2 of the disk with respect to _Z2 ; and then _calculating | T _Z1 −T _Z2 | for the warpage amounts T _Z1 and T _Z2 . 18. A common reference plane K is set on both front and back sides,
The warpage amount T_Z1, T _Z2Is warped based on the common reference plane K.
Quantity T_k1, T_k2And the amount of warpage T_k1, T _k2about
| T_k1-T_k2The disk thickness according to claim 17, wherein |
Measuring method.