JPH1089936A - Method for displaying warped shape of disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display the warped shape of a disk on a two-dimensional coordinate plane by three-dimensionally visualizing the shape. SOLUTION: An integral head D incorporated with a laser beam emitting means B which continuously emits a laser beam upon the surface of a disk A from a vertical direction and a position detecting means C which detects the deflection of the reflected beam of the laser beam from the regular reflecting position of the disk A caused by the radial warp of the disk A in a fixed relative positional relation is formed. The warped shape of the disk A is visibly displayed by means of a means E which moves the head D in parallel with the disk A in the radial direction of the disk A or moves the disk A in the radial direction by maintaining the relative position between the disk A and head D, a means F which rotates the disk A, a recording means H which records signals extracted from the signals from the means C and G at regular time intervals, and an arithmetic means I which performs arithmetic operation on the recorded signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to CD, MO, DV
The present invention relates to a method for inspecting a warp angle and a warp shape of a circular desk having a light reflective surface such as D.

[0002]

2. Description of the Related Art A conventional method for inspecting a warp angle and a warp shape of a circular desk having a light-reflective surface such as a CD, MO, and DVD includes, for example, irradiating a laser beam to a surface to be measured and reflecting the laser beam. The deflection of the beam is measured by a position detection sensor.

Conventionally, a deflection width from a specular reflection position when a beam from a light source hits a surface to be inspected perpendicularly and is reflected is measured by a position detection sensor, and the deflection width and a geometrical distance between a reflection point and a light receiving point are measured. From the relationship with the distance, a method of calculating and calculating the warp angle is adopted.

Hereinafter, a method for measuring a warp angle according to the prior art will be described with reference to the drawings. Fig. 1 shows a desk,
FIG. 7 illustrates a state where no mechanical deformation such as warpage or distortion exists. 1 is a laser irradiation device, 2
Denotes a beam splitter, 3 denotes a desk, and 4 denotes a position detection sensor.

Next, FIG. 2 shows a case where the desk is distorted and the warp angle at the laser irradiation position is inclined by θ with respect to the reference plane. From simple geometric considerations, when the desk tilt is .theta. With respect to the reference plane, the reflected light rays are reflected back at an angle equal to twice .theta. With respect to the reference plane.

[0006] The light beam reflected and returned in this way is changed its path by about 90 degrees by the beam splitter 2 and hits the light receiving surface of the position detecting sensor, whereby the center position of the beam is detected.

The position detection sensor outputs a voltage of zero level when the position where the beam hits is the center of the light receiving surface, that is, the regular reflection position. Hereinafter, according to the deviation of the light receiving surface from the regular reflection position, Outputs a voltage with a value proportional to it.

When the deviation amount δ of the reflected beam is obtained from the output of the position detection sensor, the warpage angle is generally defined as 2θ, and is obtained by the following equation.

[0009]

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

Generally, such 2θ is measured over the entire surface of the desk, and the maximum value at that time is defined as the warpage angle. θ represents the angle at which the desk is actually warped with respect to the reference plane. In Equation (1), 2θ is rad.
In the case where (L _A + L _B ) ≫δ can be assumed,
Simply _{2θ = δ / (L A +} L B) no practical problem even.

In order to measure the warp angle 2θ over the entire area of the desk, the relative positional relationship between the laser light source and the position detection sensor shown in FIG. The relative movement is made so as to coincide with the radial direction, and the output from the position detection sensor appearing at this time is sequentially read or recorded, so that the desk warp angle can be measured.

In the method of relative movement, for example, the entire surface of the desk can be scanned by fixing the laser and sensor pair and providing a mechanism for moving the desk in the horizontal direction while rotating the desk. Or, conversely, the desk is fixed at one point and simply rotated, while the laser and the sensor pair [detection head] are above the desk,
It is also possible to scan while moving in the radial direction.

When the results obtained in this manner are displayed, for example, a method in which the horizontal axis is a time axis and the output from the light receiving device is simply displayed in a time-varying manner, or a desk and a position detecting sensor are used. The warp angle is calculated from the dimensional constant determined by the geometrical arrangement of
For example, a method of taking an amount representing an angle or a position in the circumferential direction on the horizontal axis and taking a warp angle on the vertical axis is used.

However, even in these methods,
From the measurement results, there is a problem that it is difficult to intuitively grasp what shape the desk actually has and what part is distorted in what direction.

It is presumed that this is 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 desk surface.

[0016]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention approximates a three-dimensional shape by numerical operation based on numerical data of the warp angle of a circular desk obtained by the prior art, and The purpose is to provide a way to display it.

[0017]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems. As a result, when measuring the warp angle over the entire surface while rotating a circular desk, which is easily obtained by the prior art, It has been found that by introducing appropriate approximation conditions to the numerical data, a three-dimensional expression can be realized, and the present invention has been completed.

That is, the apparatus configuration according to the prior art which is premised in the present invention is composed of an irradiation means (B) for continuously irradiating a laser beam from a direction perpendicular to the surface of the desk (A), and the desk (A). A) a position detecting means (C) for detecting a deflection of the reflected beam from a regular reflection position based on the radial warpage of A), and the irradiating means (B);
And the relative position of the reflected beam position detecting means (C) is fixed and is of an integrated structure (hereinafter referred to as a detecting head (D)), wherein the detecting head (D) and the desk (A) Is relatively moved in the radial direction of the desk (A), or the desk (A) is moved in the radial direction while maintaining the relative position of the detection head (D). (E), means (F) for rotating the desk (A), means (G) for reading the rotational position of the desk (A), and position detecting means (C) for the reflected beam.
And a means (H) for extracting a signal from the rotational position reading means (G) at regular time intervals and recording the extracted signal, and a means (I) for performing arithmetic processing on the recorded signal. Things.

In the present invention, desk and disk are synonymous. The desk (A) which is an object to be measured
Must have a light-reflective surface and a circular shape.

In order to reduce the measurement error, it is desirable that the beam diameter used for laser irradiation is as small as possible, preferably 1.5 mm or less. Alternatively, it is desirable to have a mechanism that can adjust the beam diameter at the position where the reflected beam is received.

As means for detecting the position (deflection) of the reflected beam, a publicly-known position detecting element PSD (Positi
on Sensitive Device). PSD
There are both a one-dimensional type and a two-dimensional type, but a one-dimensional type is desirable in order to use the present invention effectively and at low cost.

As a means for moving the head, in which the laser irradiation means and the means for detecting the deflection of the reflected beam are integrated, relatively parallel to the radial direction of the desk, a publicly-known and publicly-known uniaxial electric slider can be used.

It is desirable that the rotation mechanism used for rotating the desk is such as to reduce variations in the rotation speed of the desk, and an AC servomotor or the like can be directly used as a power source.

As means for reading the rotational position of the desk, for example, a piece sufficient to shield light is attached to an axis for rotating the desk, and this is attached to the shaft by a publicly known photointerrupter element. There is a method of detecting that a piece has passed and generating a rotation pulse.

An A / D converter and an electronic memory are integrated as means for extracting output signals from the beam position detecting means and the rotational position detecting means at fixed time intervals and recording them as needed. A mechanism can be used. Known and publicly-known devices having such a mechanism include:
For example, there are a product name digitizer (Model S121) of Autonics Co., Ltd., and a wave name 5822 of product name of NF Circuit Block Co., Ltd.

As the means for calculating the information recorded and held in the recording means, personal computers of almost any manufacturer and model known and used can be used.

In order to make the above-mentioned components operate organically, for example, the following is performed. That is, while the desk (A) is being rotated by the rotating means (F), the spot irradiated from the detection head (D) onto the surface of the desk (A) is positioned within the light reflecting surface of the desk (A). The signal recording means (H) is relatively moved in the radial direction, and a change in the position of the reflected beam caused by the radial warpage of the desk (A) at that time is associated with the rotation angle of the desk (A). ) Are sequentially stored, and after the scanning of the entire surface of the desk is completed, the stored information is taken out and calculated by the arithmetic processing means (I).

In the above operation, when the rotation speed of the desk and the time interval of information recording are constant, the number of signal information extracted from the position detecting means (C) per rotation of the desk is constant. . Further, if a rotation pulse generated by the above-mentioned publicly known photointerrupter element is used as a timing signal for starting the extraction of the information from the position detecting means (C), the change in the position of the reflected beam can be detected. It is easy to record and store the data in association with the rotation angle.

For convenience, in the following description, the number of data extracted per one rotation of the desk is I, and the distance that the spot irradiated by the irradiating means (B) per one rotation of the desk moves in the radial direction of the desk (hereinafter referred to as “movement”). Pitch) is p.
In the above operation, the trajectory of the irradiation spot on the surface of the desk has a spiral shape as shown in FIG.

From the spiral locus, 1, 2, 2,
.., And the locus corresponding to the outermost circumference is N. The starting point of the spiral locus 1 is the position detecting means (C)
The end point of the spiral trajectory 1 is the start point of the spiral trajectory 2 corresponding to the position at which the extraction of the information from. Data extraction is performed for each trajectory so that the number of the trajectories is equal to one and at equal intervals on the same trajectory (substantially the same circle). The interval between adjacent spiral trajectories corresponds to the movement pitch p.

The method of calculating the desk shape based on the information recorded and stored in the signal recording means (H) is as follows. That is, the value of the warp at the position of the spiral locus 1 is ignored for convenience, and the area inside the locus 1 is assumed to be a plane. This assumption hardly matters in practical use. The reason is that the distortion and deformation of the actual desk are almost always large on the outer periphery of the desk and relatively small on the inner periphery, or that the desk manufacturing technology itself is improving year by year. Thus, the absolute value of the deformation of the desk itself is becoming smaller.

The data extraction by the position detecting means (C) uses the value obtained at the i-th position on the spiral locus n as X
_ni (where n = 1, 2,..., N and i = 1,
2,..., And expressed as _{I), X 1i, X 2i} , ·· X ni, ·
, X _Ni can be regarded as data extracted on substantially the same radius. Then, the value of the warp on the spiral trajectory 1 is neglected for convenience, and if the area inside the trajectory 1 is regarded as a plane, the value of the warp at the position of i on the spiral trajectory 2 (for convenience) S _2i ) is linearly approximated using X _1i as follows.

[0033]

[Formula 2] S _2i = p × sin θ _2i --- (2) formula

[0034]

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

More generally, what is obtained by changing the suffix 2 in the above equation to n is based on the value of X _Ni extracted at an arbitrary i-th position on an arbitrary spiral locus n with reference to that position. It represents the displacement S _ni at the i-th position on the next adjacent spiral locus n + 1.

A predetermined position on the inner peripheral side of the desk (A) at which recording is started by the signal recording means (H), that is, data X
A plane including the extracted position ₁₁ and perpendicularly intersecting the incident beam is defined as a reference plane, and a displacement T _ni from the reference plane at an arbitrary point is obtained by the following equation.

[0037]

(Equation 4)

Next, in order to display the warped shape of the desk (A) roughly three-dimensionally, the spiral locus drawn by the laser beam on the reference plane is displayed in a substantially elliptical shape. The distance T _ni from the reference plane at each scanning position is added to the y component of the substantially elliptical equation. That is, it can be expressed by the following equation.

[0039]

[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 sequentially connecting them with straight lines, the warped shape of the desk (A) can be visualized and displayed three-dimensionally on a two-dimensional coordinate plane. The way of connecting the coordinates (x _ni , y _ni ) is to change the i from 1 to I for n = 1 and connect them sequentially. Next, with n = 2, i is similarly connected from 1 to I. Such an operation is performed up to n = N, and the processing ends.

In the equation (5), a and b are the major and minor axes for representing the spiral locus 1 (the innermost circumference) in a substantially elliptical shape, T _ni is a value obtained by the equation (4), and p is Moving pitch,
I represents the number of data extracted per rotation of the desk (A) by the position detection means (C). I
Is determined by the required measurement accuracy, but if the value of I is small, the approximate ellipse when the coordinates (x _ni , y _ni ) are connected does not become smooth, but becomes uneven. Therefore, it is desirable that at least I ≧ 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.

As described above, according to the present invention, the warp angle obtained from the equation (1) obtained in the prior art is used as a starting point, and this is measured on the spiral locus on the desk surface by the equation (2). After the equation (3), the displacement from the reference plane is calculated by the equation (4), and the displacement is added to the y component of the substantially elliptical equation as shown in the equation (5). ) Is visualized and displayed three-dimensionally on a two-dimensional coordinate plane.

[0044]

The displacement from the reference plane is obtained based on the measured data of the warpage angle. By adding the displacement to the y component of the substantially elliptical formula and connecting the elliptical coordinates in a straight line, the warped shape can be visualized and displayed three-dimensionally on a two-dimensional coordinate plane.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments. (Components) A method for measuring the warp shape of a circular desk (A) having light reflectivity, wherein the laser beam is continuously irradiated from a direction perpendicular to the surface of the desk (A). Means (B), and position detecting means (C) for detecting a deflection of the reflected beam from a regular reflection position based on a warp of the desk (A) in a radial direction, and the irradiating means (B) And the reflected beam position detecting means (C)
Are fixed and have an integrated structure (hereinafter, referred to as a detection head (D)), and the detection head (D) relatively translates in the radial direction of the desk (A). Either means (E) in which the desk (A) translates in the radial direction while maintaining the relative position of the detection head (D), and means (F) for rotating the desk (A) Means for reading the rotational position of the desk (A), and signals from the reflected beam position detecting means (C) and the rotational position reading means (G) at regular time intervals, Means (H) for recording the extracted signal, and means (I) for arithmetically processing the recorded signal
(Method for Operating Components) A spot irradiated from the detection head (D) onto the surface of the desk (A) while rotating the desk (A) by the rotating means (F), When the parallel movement means (E) relatively moves in the radial direction within the light reflecting surface of the desk (A),
A change in the position of the reflected beam caused by a radial warp of the desk (A) is stored in the signal recording means (H) in correspondence with a rotation angle of the desk (A), and the arithmetic processing means (I) A method of displaying a warped shape for visually displaying output information obtained by the method (I), wherein the method comprises: (arithmetic processing method) wherein the signal recording means (H) starts recording. A plane including a predetermined position on the inner peripheral side of (A) and perpendicularly intersecting the incident beam is defined as a reference plane, and a point at which the reference plane intersects with the rotation axis of the desk is defined as a coordinate origin. The value of the warpage at the scanning position in the first round on the inner circumference side is ignored for convenience, and based on the information corresponding to the first round of the output signal recording means (I),
The displacement amount at the second scanning position is calculated, and similarly,
The amount of displacement at the (n + 1) th scanning position is determined based on the information corresponding to the nth rotation, and the amounts of displacement at the respective scanning positions determined one after another in this order are added together on the same radius, whereby the desk is obtained. (A) The distance T from the reference plane at the radial position and the angular position is obtained. (Display method) In order to roughly three-dimensionally display the warped shape of the desk (A), the laser beam is applied to the reference plane. The trajectory drawn above is displayed in a substantially elliptical shape. At this time, the warp shape of the desk (A) is obtained by adding the distance T from the reference plane at each scanning position to the y component of the substantially elliptical formula. The three-dimensionally visualized and displayed three-dimensionally on a two-dimensional coordinate plane.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, an example of displaying the warped shape of a CD (compact desk) having a diameter of 120 mm using the apparatus shown in FIG.

The range for measuring the warpage of the desk is from the position of 47 mm in diameter on the side where the information recording layer is located to the diameter of 116 mm.
mm.

In this apparatus, the rotation speed of the desk is kept constant at 12 rotations per second, the data extraction interval of the position detection sensor is 833 μsec, and the movement pitch of the detection head is p =
When operated to 1.08 mm, desk 1
The number of data extractions per rotation was I = 100, and the number of scans (the number of rotations of the spiral locus) was 32. Therefore, in the present embodiment, the total number of measurement data to be calculated is 3,200.

Next, FIG. 5 shows a three-dimensionally visualized display of the warped shape of the desk using the method of the present invention. The displacement T _ni from the reference plane was determined in μm units, and the numerical values were added in equation (5). The scale can be scaled by setting the entire PC screen to 1400 horizontally and 105 vertically.
The image was scaled so as to be 0, 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. 5A shows that when the value of the enhancement coefficient κ is 1,
FIG. 5B shows the case of 3, and FIG. 5C shows the case of 5. The data on which the calculation is based is the same for all of (a) to (c). The * mark shown in the figure indicates a point where the value of the warpage (displacement) from the reference plane is maximum.
Numerically, the displacement was only about 50 μm even at the maximum point, but it can be seen that as the value of the enhancement coefficient κ increases, the state of the warpage is more clearly expressed.

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

[0052]

According to the present invention, the warp measurement data, which has conventionally been merely a series of numerical values, is visualized and displayed three-dimensionally on a two-dimensional coordinate plane so that the real shape of the desk can be intuitively grasped. became.

[0053]

[Brief description of the drawings]

[0054]

FIG. 1 is a diagram illustrating an example of a method of measuring a warp angle according to a conventional technique.

[0055]

FIG. 2 is a diagram showing a state in which a laser beam swings when a desk to be measured has a warp in FIG.

[0056]

FIG. 3 is a diagram illustrating an example of a hardware configuration when the method of the present invention is applied.

[0057]

FIG. 4 is a diagram showing a trajectory of an irradiation spot tracing on the desk surface, and black dots in the figure represent points where data is extracted.

[0058]

FIG. 5 is a diagram illustrating an example in which a desk shape is three-dimensionally visualized and displayed on a two-dimensional coordinate plane by the method of the present invention.

[0059]

[Explanation of symbols]

Reference Signs List 1 semiconductor laser beam irradiation device 2 beam splitter 3 desk (measurement object) 4 position detection element (position detection sensor) 5 reference plane 6 mark indicating maximum displacement position (A) desk (B) laser beam irradiation means (C) position Detecting means (D) Detecting head (E) Detecting head moving means (F) Desk rotating means (G) Detecting means for rotating desk position (rotating pulse generating means) (H) Information recording means (I) Information processing means

Claims (1)

[Claims] 1. A method for measuring a warped shape of a circular desk (A) having light reflectivity, comprising irradiating a laser beam continuously from a direction perpendicular to the surface of the desk (A). Means (B), and position detecting means (C) for detecting a deflection of the reflected beam from a regular reflection position based on a warp of the desk (A) in a radial direction, and the irradiating means (B) And the relative position of the reflected beam position detecting means (C) is fixed, and has an integrated structure (hereinafter referred to as a detecting head (D)), wherein the detecting head (D)
Either translates relatively in the radial direction of the desk (A), or translates the disk (A) in the radial direction while maintaining the relative position of the detection head (D) ( E), means for rotating the desk (A) (F), means for reading the rotational position of the desk (A) (G), means for detecting the position of the reflected beam (C) and means for reading the rotational position Means for extracting the signal from (G) at regular time intervals and recording the extracted signal; and means for processing the recorded signal (I).
A spot irradiated from the detection head (D) on the surface of the desk (A) while the desk (A) is being rotated by the rotating means (F) by the parallel moving means (E). The change in the position of the reflected beam caused by the radial warpage of the desk (A) when the desk (A) is relatively moved in the radial direction within the light reflecting surface of the desk (A) is determined by the A desk warp shape display method for storing in the signal recording means (H) corresponding to a rotation angle, calculating by the arithmetic processing means (I), and visually displaying output information obtained thereby. A plane which includes a predetermined position on the inner peripheral side of the desk (A), at which recording is started by the signal recording means (H), and which intersects perpendicularly with the incident beam as a reference plane; The point where the axis intersects is taken as the coordinate origin, The value of the warpage at the scanning position in the first round on the inner circumference side of the disk (A) is ignored for the sake of convenience, and the second round based on the information corresponding to the first round of the output signal recording means (I). The displacement amount at the scanning position is obtained, and similarly, the displacement amount at the (n + 1) th scanning position is obtained based on the information corresponding to the nth rotation. , The distance T from the reference plane at the radial position and the angular position of the desk (A) is obtained by adding them on the same radius,
In order to display the warped shape of the desk (A) roughly three-dimensionally, the trajectory drawn by the laser beam on the reference plane is displayed in a substantially elliptical shape.
By adding the distance T from the reference plane at each scanning position, the warped shape of the desk (A) is reduced by 2
The method for displaying the distortion shape of the desk (A), wherein the distortion shape is visualized and displayed three-dimensionally on a three-dimensional coordinate plane.