JPS63125912A - Lighting device for measurement - Google Patents

Abstract

PURPOSE:To handle variation in optical path length and to realize lighting with high reproducibility by installing two polarizing plates in front of a light source at right angles to the optical axis and coupling one polarizing plate with a rotary driving means which controls the relative angle to the other polarizing plate. CONSTITUTION:A lighting device 1 for measurement is equipped with a lamp 2 as the light source, the two polarizing plates 3 and 4, a condenser lens 5, a half-mirror 6, the rotary driving means which controls the relative angle thetaof one polarizing plate to the other polarizing plate, a photosensor 11, a power source 12 for the lamp, and a light quantity controller 13. Then, the lighting device 1 for measurement is so constituted that the part including the lamp 2, two polarizing plates 3 and 4, condenser lens 5, and photosensor 11 is a closed type. The two polarizing plates 3 and 4 are installed in front of the lamp 2 at right angles to the optical axis 0-0. The polarizing plate 3 is fixed and the polarizing plate 4 is coupled with the rotary driving means. Consequently, the quantity of light is accurately adjusted according to a mathematical expression, so the lighting with high reproducibility is obtained with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a measurement device used in conjunction with an optical measurement device that optically measures the position or shape of a component.
The present invention relates to a measurement illumination device suitable for measurements that require control of the amount of illumination light.

[Conventional technology]

In precision assembly equipment, precision processing machines, etc., illumination conditions greatly affect measurement of the position or shape of optical components.

For example, a measuring device that measures reflected light must adjust the illumination method and source depending on the material of the object to be measured. Therefore, when assembling multiple parts made of different materials, it is common practice to adjust the voltage of the light source or switch the ND filter for precision measurement illumination, but adjusting the voltage of the light source has poor reproducibility and the illuminance When used at a low setting, there is a drawback that the peripheral area becomes dark in a point-symmetric illuminance distribution. Furthermore, the ND filter switching method is not suitable for adjusting fine elements.

In addition, as a conventional technology for lighting for equipment,
The technology described in Publication No. 42457 and 1, Special Publication No. 5
There is a technique described in Japanese Patent No. 8-52572.

However, the former concerns the structure of a copying machine that is equipped with a polarizing plate and uniformly illuminates the object to be irradiated, whereas the latter concerns changes in the dimensions of the object to be irradiated, such as paper size A4, A5, etc.
Exposure methods that correspond to changes in plates, etc. (This is related to two methods and is different from the gist of the present invention.

[Problem that the invention seeks to solve]

Assembling precision parts: As an example of a related parts measurement method,
When measuring multiple parts made of different materials, the amount of reflected light on the observation surface varies depending on the material, so it is necessary to adjust the illumination to match the sensitivity of the visual sensor. The higher the measurement accuracy, the more difficult the adjustment becomes.

Conventional techniques deal with this problem by adjusting the voltage of the light source or switching the ND filter, but these problems have problems such as poor reproducibility and limited adjustment range.

An object of the present invention is to solve the above-mentioned problems and apply it to an optical measurement device, which is not limited to the material of the object to be measured, and can also cope with changes in optical path length due to focusing in three-dimensional measurement. It is an object of the present invention to provide a measurement illumination device that can provide illumination with high accuracy and high reproducibility.

[Means for solving problems]

The above purpose is to install two polarizing plates perpendicular to the original axis in front of the light source, and to control the relative angle of one polarizing plate with respect to the other polarizing plate. Above all, it is achieved.

[Effect]

When the illuminance of the light source is constant, the amount of light y that passes through the two polarizing plates installed on the original axis has the following relationship with respect to the relative angle θ between the two polarizing plates.

'f = k cos2...
・+11 Here, k: Constant Therefore, by determining the amount of light suitable for the material of the object to be measured in advance, converting the data into a table, and inputting it into a microcomputer or presetter to drive the rotational drive means, One polarizing plate can be rotated depending on the required amount of light.

Therefore, it is not limited to the material of the object to be measured, and can also be adapted to changes in optical path length due to focusing in three-dimensional measurement.

Further, the light amount can be adjusted accurately according to a mathematical formula, and as a result, illumination with high precision and high reproducibility can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to Figures 1 to 4.

Fig. 1 is a configuration diagram of an embodiment of an optical measurement device to which a measurement illumination device according to the present invention is applied, Fig. 2 is a perspective view showing an embodiment of the measurement illumination device, and Fig. 5 shows two images. FIG. 4 is a block diagram showing an embodiment of a light amount control circuit.

The optical measuring device of this embodiment is used for precision assembly of magnetic disk drives.

In assembling the magnetic disk device, as shown in the first factor, the inner diameter edge of the disk-shaped magnetic disk 26, which is a fitting part, and the outer diameter edge of the cylindrical spindle 25 are measured, and the measurement data is recorded. This involves positioning or correcting the position of parts based on (-) precision assembly on the micron order, which requires control of measurement lighting with high reproducibility.

As shown in FIG. 1, the measurement illumination device 1 in this embodiment includes a lamp 2 as a light source and two polarizing plates 5 and 4.
, a focusing lens 5, a half mirror 6, a rotation drive means for controlling the relative angle θ of one polarizing plate with respect to the other polarizing plate, an optical sensor 11, a lamp power source 12, and a light amount control device. 13. The measurement illumination device 1 has a closed portion that covers the lamp 2, the two polarizing plates 3 and 4, the focusing lens 5, and the optical sensor 11.

The two polarizing plates 5 and 4 are placed in front of the lamp 2 with the optical axis 0.
It is installed perpendicular to -0. Of the two polarizing plates 3 and 4, the polarizing plate 6 is fixed, and the polarizing plate 4
is connected to rotational drive means.

The focusing lens 5 is arranged in front of the polarizing plate 4, and the half mirror 6 is arranged in front of the focusing lens 5.

As shown in FIGS. 1 and 2, the rotational drive means includes a motor 7, a drive gear 8 attached to the motor, and a driven gear formed on the outer periphery of the polarizing plate 4 and meshed with the drive gear 8. 9. In addition, around the driven gear 9, there is a gear 1 for preventing the center of the polarizing plate 4 from being captured.
0 is placed.

The optical sensor 11 is set so that when the voltage applied to the lamp 2 is 0 (zero), the output signal is also 0. This optical sensor 11 is connected from the lamp 2 to the polarizing plate 3.
4, passes through a focusing lens 5 and a half mirror 6, and is irradiated onto a non-measurement object through an optical measuring device 14. A part of the light is captured through the half mirror 6, and the amount of the light is actually measured; The light is output to a light amount control device 13.

The lamp power source 12 outputs a light amount exceeding the amount of light required for measurement so that the lamp 2 can emit light, and maintains the output at a constant value.

As shown in FIG. 4, the light amount control device 15 includes an amplifier 51 that amplifies the output of the optical sensor f11, an A/D converter 62, a data table 35, a presetter 34,
It is configured to include a subtracter 55 and a motor controller 36.

The A/D converter 52 converts an analog signal, which is a detection signal of the amount of light output from the optical sensor 1j, into a digital signal and sends it to the subtracter 35.

The data table 33 stores data 33' obtained experimentally in advance about the amount of light depending on the material of the object to be measured and the amount of light depending on the change in the optical path length.

The data 56' is input to the presetter 34.

The subtracter 35 receives an output signal from the presetter 54 regarding the amount of light corresponding to the material of the non-measurable object and the amount of light corresponding to the optical path length, and outputs the output signal from the presetter 54 to the optical sensor 11, the amplifier 51, and the A/D.
The converter 32 takes in the output signal (■) regarding the actual measured value of the amount of light directed from the lamp 2 to the optical measuring device 14, subtracts the output signal (■) and the output signal (■), and outputs the difference to the motor controller 56. It has become.

The motor controller 56 is configured to input the subtraction result from the subtraction i 35 , output a control signal to the motor 7 of the polarizing plate 40 rotation drive means based on this, and drive the motor 7.

On the other hand, as shown in FIG. 1, the optical measuring device 14 includes a line sensor 15 as a visual sensor, a cylindrical lens 16 installed in front of the line sensor, an interference filter 17, a half mirror 18, and an objective lens 19. It is configured with.

Also, 1↑1 optical measuring device 14 is shown in Fig. 1? - As shown, a focusing device 20 and an image processing device 21 are provided, and the image processing device 21 further includes an arithmetic processing device 2.
2 are connected.

On the other hand, as shown in FIG. 1, the magnetic disk device assembly apparatus includes an XY table 23 and a vacuum suction ring 27 attached to an arm 28. An assembly of a base 24 and a spindle 25 of a magnetic disk device is mounted on the XY table 23.

The vacuum suction ring 27 is connected to a vacuum supply source (not shown) and is configured to suction and hold the magnetic disk 26. Also, the vacuum suction ring 27 is attached to the arm 28
It is supported so as to be movable toward and away from the XY table 25 and to be slightly movable in the XY directions.

The measurement illumination device 1 of the embodiment described above is used and operates in the following manner during measurement and assembly of a magnetic disk device.

First, the XY table 23 of the magnetic disk device assembly device
As shown in Figure 1, the base 2 of the magnetic disk drive
4 and the spindle 25, and the spindle 25 is fixed by controlling its posture using a posture control mechanism (not shown) so that the spindle 25 is vertical.

Further, the magnetic disk 26 is attracted and held by a vacuum suction ring 27 supported by an arm 28 of a magnetic disk device assembly device.

Then, the spindle 25 is measured by the optical measuring device 14.
The outer diameter edge of the magnetic disk 26 is then measured, and then the inner diameter edge of the magnetic disk 26 is measured.

At the time of measurement 1 described above: Lamp power source 1 of measurement lighting device 1
2, a voltage is applied to the lamp 2 to turn it on.

As can be seen from FIGS. 1 and 2, the light emitted from the lamp 2 passes through two polarizing plates 3 and 4, passes through a focusing lens 5 and a half mirror 6, and then reaches an optical measuring device 1.
4, the half mirror 18 of this optical measuring device 14
The light is then irradiated through the objective lens 19 onto the inner edge of the magnetic disk 26 and the outer edge of the spindle 25 as objects to be measured.

A part of the light irradiated onto the object to be measured is branched by the half mirror 6 of the measurement illumination device 1 to the optical sensor 11, and the amount of the light is actually measured. The actual measured value of the light amount by this optical sensor 11 is output to the light amount control device 13, as shown in FIGS. 1 and 4.

The problems here are: ■ Since the materials of the object to be measured, that is, the materials of the magnetic disk 26 and the spindle 25 in this example, are different, the amount of reflected light from the observation surface is also different; ■ For focusing the two parts. , the optical path length changes;

In contrast, in this embodiment according to the invention, the lamp 2
The light intensity is set to an intensity that exceeds the light intensity required for measurement, and is kept at a constant value.

In addition, two polarizing plates 5 and 4 installed in front of the lamp 2
Of these, the polarizing plate 5 is fixed, the motor 7 is driven, and the polarizing plate 4 is rotated via a driving gear 8 and a driven gear 9. When one of the polarizing plates 4 is rotated with respect to the other polarizing plate 5, the photoelectric power transmitted through the two polarizing plates 6 and 4 will be changed to the fifth polarizing plate from the relative angle θ1: As shown in the figure, the curve is expressed by the above equation (1). In other words, polarizing plate 4 is
By rotating it by 0°, it becomes possible to adjust the amount of light with high reproducibility in accordance with Equation C2.

The portion including the lamp 2, the ζ polarizing plates 5 and 4, the focusing lens 5, the half mirror 6, and the optical sensor 11 is a closed type, and when the voltage applied to the lamp 2 is set to 0, the optical sensor 11 By setting the output signal to also be 0, the illumination curve becomes ideal as shown in FIG.

Note that since the output side of the half mirror 6 is connected to the measurement lens barrel, backlight can be ignored.

Furthermore, the amount of light is controlled in response to differences in the material of the object to be measured and changes in the optical path length as follows.

That is, the amount of light due to the difference in the material of the object to be measured and the amount of light due to the change in the optical path length are determined experimentally in advance, and the data 33
' is stored in the data table 65 of the light amount control device 15.

Then, when controlling the amount of light, data 36' is input to the presetter 34, and its output signal (2) is sent to the subtracter 35, as shown in FIG. Further, the output signal ① regarding the actual measurement value of the light 1 by the optical sensor 11 is also sent to the subtracter 65 .

The subtracter 35 subtracts the output signal (2) and the output signal (2), and outputs the subtraction result to the motor controller 36.

The motor controller 36 sends a control signal to the motor 7 based on the difference between the output signal (1) and the output signal (2) determined by the subtracter 55, and drives the motor 7.

This allows for differences in the material of the object to be measured and changes in optical path length C.
Highly accurate light intensity adjustment is also possible for both.

The object to be measured is irradiated with an appropriate amount of light adjusted by the measurement illumination device 1, and the outer diameter edge of the spindle 25 of the magnetic head device and the inner diameter edge of the magnetic disk 26 are measured by the optical measurement device 14. Then, calculate the amount of positional deviation.

Next, based on the amount of positional deviation, the fine positioning mechanism (
(not shown), the position of the magnetic disk 26 is corrected, and the magnetic disk 26 is inserted into the spindle 25.

The above-mentioned work (:) enables precision assembly on the micron order.

In the present invention, the specific structures of the light amount control device 13, the optical measurement device 14, and the assembly device are not limited to the embodiments shown in the drawings, and may be any structure as long as it has the intended function.

Further, the present invention is of course applicable not only to illumination for measuring the spindle 25 and magnetic disk 26 of a magnetic disk device, but also to optical measurement in general.

[Effects of the Invention] According to the present invention described above, two polarizing plates are installed perpendicularly to the optical axis in front of the light source, and one polarizing plate is set at a relative angle to the other polarizing plate. It is connected to a rotational drive means for controlling, and can be applied to optical measurement devices to accurately respond to changes in optical path length due to focusing in three-dimensional measurement, regardless of the material of the object to be measured. This has the effect of increasing versatility.

Further, according to the present invention, since photoelectric adjustment can be performed accurately in accordance with mathematical formulas, it is possible to obtain illumination with high precision and high reproducibility, and is particularly effective for precision measurement.

[Brief explanation of the drawing]

The first factor is a configuration diagram of an embodiment of an optical measurement device to which the measurement illumination device according to the present invention is applied, Fig. 2 is a perspective view showing an embodiment of the measurement illumination device, and Fig. 5 shows two images. In the characteristic diagram of the relative angle of the polarizing plate and the amount of transmitted light, the fourth factor is a block diagram showing an embodiment of the light amount control circuit. DESCRIPTION OF SYMBOLS 1... Measurement illumination device, 2... Lamp as a light source, 3, 4... Polarizing plate, 7... Motor of rotation drive device for polarizing plate, 11... Optical sensor, 12... -Lamp power source, 13...Light amount control device, 14...Optical measurement device, 25...Spindle of magnetic disk device as a measured object, 26...Magnetic disk, 0-0... -The optical axis of the light emitted from the lamp. 2. ;-″Pape-,7

Claims (1)

[Claims] 1. Two polarizing plates are installed in front of the light source perpendicular to the optical axis, and one polarizing plate is connected to a rotation drive means that controls the relative angle with respect to the other polarizing plate. Lighting device for measurement.