JP2626611B2 - Object shape measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to the measurement method of the shape of an object, in particular, measurement object shape can be measured the surface shape and contours optically from stationary objects to fast moving objects
Related to the setting method .

[0002]

2. Description of the Related Art Conventionally, as a technique for measuring the shape of an object of this type, a two-dimensional imaging camera such as a television camera is used to fix a target object and image the object with the imaging camera to obtain a two-dimensional image pattern. In most cases, the surface of an object is measured by obtaining a signal and performing image processing, and is not particularly suitable for measuring an object moving at high speed. A method of measuring the shape of a moving object using a two-dimensional image sensor is also known, but requires a laser light source, a special image sensor, or an imaging camera to eliminate the influence of the flow of the image of the object. And had

For example, as a method for optically measuring the shape of an object moving at high speed, a light-cut image of the object is formed by using a plate-like light source or a laser scanning light source of a semiconductor laser that emits light in a pulsed manner. On the side, by using a special imaging camera using a two-dimensional semiconductor imaging device as a delay integration type linear array, by superimposing the light-section image while shifting it little by little and processing the imaging signal, the moving object The measurement of the surface is described in JP-A-4-348221.

[0004]

The above-mentioned conventional technology for measuring the shape of an object to be measured essentially uses a two-dimensional image sensor to perform spatial signal processing, and is suitable for measuring a moving object. In addition, a device that measures a moving object requires a laser light source, a special imaging camera, and the like in order to eliminate the influence of the image flow. The present invention makes it possible to measure the shape of an object with high accuracy by using a rotating mirror and a one-dimensional image sensor. That is, an object of the present invention is to provide an object shape measuring method which can measure the shape of an object moving at a high speed with a high resolution with little influence of the image flow.

Another object of the present invention is to provide an object shape measuring method capable of measuring a shape of a predetermined point or a line portion of an object to be measured or a continuous shape in a predetermined width range with high accuracy. For other purposes.

[0006]

In order to achieve the above object, the present invention provides a rotating mirror facing a measurement portion of an object to be measured according to each of stationary, low-speed movement and high-speed movement of the object. Low-speed rotation, rotation stop and substantially synchronous rotation state, the reflected light from the rotating mirror is focused on a one-dimensional image sensor by an imaging lens, and a line image is detected by the one-dimensional image sensor. The configuration is adopted. In addition, as an object shape measurement device, an illumination device that irradiates light to the surface of the object to be measured, a rotating mirror that reflects a measurement portion of the object to be measured, a control device that controls rotation and stop of the rotating mirror, and a rotating mirror An imaging lens for condensing reflected light from the imaging lens, a one-dimensional image sensor positioned on a focal plane of the imaging lens to detect a line image of the device under test, and a processing device for processing a signal from the one-dimensional image sensor. The configuration is characterized by the following.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an entire configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an object to be measured, 2 denotes a point or planar backlight source for providing background light, 3 denotes a polygonal rotating mirror, 4 denotes a driving motor for the rotating mirror, 5 denotes a one-dimensional imaging lens system, and 6 denotes a one-dimensional lens system. Denotes an image sensor (hereinafter, referred to as a CCD) such as a one-dimensional charge-coupled device, 7 denotes an image processing device, 8 denotes a display device, 9 denotes a control device for controlling rotation and stop of a rotating mirror, and 10 denotes a control device. This is a stage for fixing or transporting the measurement object.

In the arrangement of the device under test and the measuring device shown in FIG. 1, a description will first be given of a case where the movement of the device under test 1 and the rotation of the rotating mirror 3 are stopped to perform the measurement. In such an arrangement of the light source, the DUT, and the rotating mirror,
Since the DUT 1 partially blocks the backlight emitted from behind, the image of the DUT can be viewed from the rotating mirror 3 as an image in which the brightness and darkness are vertically separated from the outer shape or the edge of the DUT 1. A bright and dark image is incident on the rotating mirror 3. The bright / dark image is reflected by the rotating mirror 3 and enters the imaging one-dimensional lens 5. The imaging one-dimensional lens 5 refracts and condenses the light from the rotating mirror 3 to form an image on a surface including the one-dimensional CCD 6 as an image whose edge portion can be distinguished by a vertical boundary between light and dark. This image is an image in a visible range of the DUT 1 according to the area of the rotating mirror 3 and is wider than the width of the one-dimensional CCD 6 determined by the characteristics of the imaging one-dimensional lens 5 and the like. However, as shown in FIG. 2, the image itself on the one-dimensional CCD 6 is a single line image in the vertical direction of the image from the DUT 1 that has received the backlight, and one point of the outer shape of the DUT 1 Can be read from the output of the one-dimensional CCD 6. This output waveform is shown in FIG. The electric charge in the one-dimensional CCD 6 is sufficiently accumulated in the element in the bright part where the backlight light is incident, and is hardly accumulated in the element in the dark part interrupted by the DUT 1, so that the electric charge is read out from the one-dimensional CCD 6. The output waveform becomes a pulse-like waveform in which the output level suddenly changes at a position corresponding to the edge. The position of the edge can be measured by detecting the change point of the waveform.

The above is the case where the measurement of the shape of the object is performed with both the DUT 1 and the rotating mirror 3 stopped, and then the measurement is performed by moving or rotating one of the DUT 1 and the rotating mirror 3. Will be described. When viewed from the one-dimensional CCD 6 side, an image of a certain range of the DUT 1 is projected on the rotating mirror 3 as shown in FIG. 3A, and the relative movement of the DUT 1 and the rotating mirror 3 causes One-dimensional CC via optical system
The line image formed on D6 moves with time. That is, the one-dimensional CCD 6 scans the edge line of the DUT 1 horizontally. As the reading speed of the one-dimensional CCD 6 is increased, as shown in FIG.
At a resolution determined by a minute length ΔR of the DUT 1 at an interval determined by the time required for the feed or rotation of the rotating mirror 3 and the charging of the one-dimensional CCD 6 (about Δt) (edge line).
Can be measured.

In this case, in the image processing device 7, FIG.
As shown in FIG. 4 (A), the edge position information of each signal read on the time axis is rearranged into distance information for each Δt, and interpolation processing or the like is performed as necessary, as shown in FIG. 4 (B). Then, it is converted into a two-dimensional image output converted into edge position information on the time axis, and can be displayed on the display device 8 or the like. As described above, when the object to be measured is moved slowly, or when the object to be measured does not move, the rotating mirror is rotated to measure the outer shape and the like.

Next, considering the case where the DUT 1 moves at a high speed and the rotating mirror 3 is stationary, in this case, since the reading speed of the one-dimensional CCD 6 is limited, the line image has a flowing shape. Accurate measurements are not possible. In the present invention, in this case, the driving of the rotating mirror 3 is controlled by the control device 9, and the rotating mirror is rotated substantially synchronously in accordance with the moving direction of the DUT 1 to stop the image flow for measurement. That is,
By controlling the rotating mirror, the image can be apparently stopped or slowed down, so that the desired edge of the measured object can be measured with high resolution.

When the rotation speed of the rotating mirror 3 is completely synchronized with the movement of the DUT 1, the line image of the reflection image on each surface of the polygonal mirror will appear to stop on the one-dimensional CCD 6. Since only one point of the edge of the DUT 1 is measured, discrete points of the DUT 1 can be accurately measured. Furthermore, when measuring the edge line of the DUT 1 in units of a fixed width, the synchronization of the rotation of the rotating mirror is slightly shifted and the one-dimensional C
An image flow is generated in the range of the allowable speed for reading the line image on the CD 6, and the edge line of the DUT 1 is measured for each mirror surface. FIG. 5 shows a point or a measurement portion having a constant width, and FIG. 4C shows an edge position output obtained by converting the measurement output into the two-dimensional image signal.

In the measurement of the object shape of the above-described embodiment, since the backlight light source 2 is used, the measurement is limited to the measurement of the edge of the DUT 1. Light from a single light source is irradiated from the rotating mirror 3 side, and further light sources are added above the DUT 1 and on the side opposite to the backlight light source 2 in addition to the backlight light source 2. Is adjusted to make the shape of the DUT 1 rise, and the same measurement as described above is performed, the shape of each part other than the edge of the DUT 1 can be measured. In this case, the output waveform read out from the one-dimensional CCD 6 is a signal having many irregularities, and the waveform processing for discriminating the level of each irregularity is performed by image processing using hardware or software such as a multistage comparator group or a computer. To generate a two-dimensional or three-dimensional image signal. By such a measurement, it becomes possible to display the shape of the edge, burr, irregularities, holes, defects, etc. of the DUT 1 on the display device 8.

[0015]

As described above, the present invention makes it possible to measure the shape of an object with high accuracy by using a rotating mirror and a one-dimensional image sensor. The most suitable measurement method can be selected according to the conditions. For example, the shape of an object moving at a low speed can be measured by stopping the rotation of the rotating mirror, and the shape of a stopped object can be measured by rotating the rotating mirror at a low speed. it can. In particular, in measuring the shape of an object moving at high speed, by rotating the moving speed of the DUT 1 and the rotation angle of the rotating mirror 3 substantially in synchronization, the shape that cannot be measured due to the flow of the image is measured. Measurement can be performed, and the measurement accuracy of the object shape can be significantly improved. Further, it is also possible to completely synchronize the rotation of the rotating mirror with respect to the object to be measured and measure the measurement point of the object to be measured with high resolution.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating a state of an optical system for forming a line image of an object to be measured.

FIG. 3 is a diagram illustrating a relationship between movement of a line image and a reading operation of a one-dimensional image sensor.

FIG. 4 is a diagram showing a read output of the one-dimensional image sensor and an image processing output thereof.

FIG. 5 is a diagram showing a measurement portion of an object to be measured.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be measured 2 backlight light source 3 rotating mirror 4 motor 5 imaging lens system 6 one-dimensional image sensor (CCD) 7 image processing device 8 display device 9 control device 10 stage

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 7/18 G06F 15/62 400

Claims (1)

(57) [Claims] 1. A rotating mirror facing a measurement portion of an object to be measured is set in a stationary, low-speed movement, or high-speed movement state of the object to be measured.
Low-speed rotation, rotation stop and approximately synchronous rotation respectively
A state, and condensed on the one-dimensional image sensor by the reflected light imaging lens from the rotating mirror, the object shape measuring method and detecting a more linear image the one-dimensional image sensor.