JP3645975B2 - Measuring device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a measurement apparatus, and more particularly to a measurement apparatus that improves the measurement accuracy of three-dimensional measurement.
[0002]
[Prior art]
An example of a conventional measuring apparatus is shown in FIG. This measuring apparatus is disposed on an XY table 1 on which an object 2 having stepped portions 2a, 2b, 2c is placed and moves in the X and Y directions on the base. 2 is configured by a reading device 3 such as a CCD camera or a laser displacement meter that reads an arbitrary point of 2 with a measuring medium such as visible light.
[0003]
In the measuring apparatus having the above configuration, the XY table 1 on which the object to be measured 2 is placed is moved in the X and Y directions with respect to the reading apparatus 3, and the reading apparatus 3 makes an arbitrary point on the object to be measured 2 visible. Read with a measurement medium such as light. At this time, the step portions 2a, 2b, 2c of the measurement object 2 can be measured by measuring the distances between the step portions 2a, 2b, 2c of the reading device 3 and the measurement object 2.
[0004]
[Problems to be solved by the invention]
However, according to the conventional measuring apparatus, when the XY table is moved in the XY plane in order to read an arbitrary point of the object 2 to be measured, some displacement occurs in the Z direction due to the mechanical accuracy of the XY table 1. . The displacement in the Z direction generated here causes an error in each measured value of the stepped portions 2a, 2b, and 2c of the object 2 to be measured, and there is a disadvantage that the measurement accuracy is lowered.
[0005]
Accordingly, an object of the present invention is to provide a measuring apparatus that can improve the measurement accuracy of three-dimensional measurement.
[0006]
[Means for Solving the Problems]
In view of the above problems, the present invention improves the three-dimensional measurement accuracy.
A table on which the object to be measured is placed to perform one-dimensional or two-dimensional movement;
A marker plate having a high degree of flatness, having a light-transmitting and measuring unit marker that can be optically confirmed on a surface, and fixed to the table so as not to cause relative displacement with the table;
Reading means for performing relative movement with the table and reading the object to be measured and the marker plate;
Provided is a measuring apparatus comprising a calculating means for calculating a measurement value of the object to be measured based on a displacement amount of the reading means displaced to read the object to be measured and the marker plate. is there.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the measuring apparatus of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
1 and 2 show an embodiment of the measuring device of the present invention. This measuring apparatus has an XY table 1 that moves in the X and Y directions by placing an object to be measured (a workpiece such as a lead frame) 2 having stepped portions 2a, 2b, and 2c, and an XY table 1 surface. A reading device 3 such as a CCD camera that reads the respective surfaces by moving in the vertical direction and focusing on an arbitrary point of the measuring object 2 and a marker plate 4A described later, and the reading device 3 is connected to the measuring object 2 and When focusing on each of the markers 4A, the displacement meter 6 that measures the distance moved is disposed between the XY table 1 and the reader 3, and performs the same movement as the XY table 1, and the marker 4A is placed on the surface. And a marker plate 4 having a high flatness made of a material such as glass that transmits light, and an arithmetic unit 5 that calculates a measurement value of the measurement object 2 based on data from the reading device 3 and the displacement meter 6. Is made up of . The depth of focus of the optical system of the reading device 3 is smaller than the distance between the marker plate 4 and the measurement object 2 and is equal to or less than an allowable error. The marker plate 4 is also shown, for example, in JP-A-7-318311. In the present invention, the plane of the marker plate 4 is also used as a reference plane for height measurement.
[0009]
In the measuring apparatus having the above configuration, the stepped portion 2b is read by aligning the focus of the reading device 3 with the stepped portion 2b of the object 2 to be measured, as shown in FIG. The illustrated WD is a constant determined by the characteristics of the optical system of the reading device 3. Next, as shown in FIG. 3B, the reading device 3 is moved vertically upward to focus on the marker plate 4, and the marker 4A (FIG. 2) on the marker plate 4 is read. At this time, the displacement amount h ′ of the reading device 3 is measured by the displacement meter 6. In this manner, the displacement amount h ′ from the displacement meter 6 and the position information of the marker 4A from the reading device 3 are input to the arithmetic device 5. The calculation device 5 calculates the position h in the Z direction of the stepped portion 2b of the measurement object 2 from these pieces of information as h = h ′, and calculates and outputs the position of the XY plane. However, the unevenness of the workpiece is not this h itself, but the plane of the reference surface is obtained by calculation from each h when three or more reference surfaces of the workpiece are measured. Since the unevenness of each point of the workpiece is calculated as a difference from this plane, the workpiece and the marker plate do not necessarily have to be parallel within the allowable error range.
[0010]
In the above embodiment, the XY table 1 has been described as moving along the XY plane together with the marker plate 4. However, the XY table 1 and the marker plate 4 are fixed so as to be stationary, and the reader 3 The displacement meter 6 may be moved on the XY plane.
[0011]
【The invention's effect】
As described above, according to the measurement device of the present invention, the table and the marker plate for placing the measurement object are fixed, and the reading device is focused on the measurement point and the marker plate of the measurement object, respectively. Since the three-dimensional measurement of the measurement point is performed from the displacement amount of the reading device and the position information of the marker plate, an error based on the mechanical accuracy of the table, in particular, the perpendicularity in the Z direction is eliminated and the object to be measured with high accuracy Can be measured.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a measuring device according to an embodiment of the present invention.
FIG. 2 is a top view showing the measuring apparatus of FIG.
FIG. 3 is an explanatory diagram showing a measurement operation of the measurement apparatus of FIG.
FIG. 4 is an explanatory view showing a conventional measuring apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 XY table 2 To-be-measured object 2a, 2b, 2c Step part 3 Reading apparatus 4 Marker board 4A Marker 5 Arithmetic unit 6 Displacement meter

Claims (4)

A table on which the object to be measured is placed to perform one-dimensional or two-dimensional movement;
A marker plate having light transmittance and having a measurement unit marker that can be optically confirmed on the surface, and fixed to the table so as not to cause relative displacement with the table;
Reading means for performing relative movement with the table and reading the object to be measured and the marker plate;
A measuring apparatus comprising: a calculating unit that calculates a measurement value of the measurement object based on a displacement amount that the reading unit is displaced to read the measurement object and the marker plate. The measurement apparatus according to claim 1, wherein the reading unit has a depth of focus that is equal to or less than an allowable error of the measurement value. The measuring apparatus according to claim 1, wherein the calculation means calculates a one-dimensional, two-dimensional, and three-dimensional measurement value of the object to be measured. The measuring apparatus according to claim 1, wherein the marker plate has a predetermined flatness.

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