SU1444836A1 - Method of detecting the boundary of flat object - Google Patents

Abstract

The invention relates to automation and computer technology, in particular, to methods of introducing an image border, and can be used in selecting the border of a flat object when scanning it with a directional light flux. The purpose of the invention is to detect sensitivity. The method consists in scanning an object directed at an angle to the plane of an object by a light flux, recording the reflected light flux at a distance R from the object, simultaneously detecting a diffuse light flux at distances R and then subtracting the signal value registered at the distance R, from the value of the signal registered at the distance K, while the sign of the result is preserved and R /: R. 2 Il

Description

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The invention relates to automation and computer technology, in particular, to methods such as the border of an image, and can be used to select the border of an image of a flat object when it is scanned with a directional light flux. The purpose of the invention is to increase the sensitivity when parting the face of an image of a flat object when the latter is scanned with a directional light beam.

The method consists in scanning an object with a directional light at an angle to the object's plane, registering a reflected directional light flux at a distance R from an object, simultaneously registering a reflected diffuse light flux at a distance R, and K and subtracting the value of the signal recorded at a distance K, from the value of the signal recorded at the distance R, the sign of the result is preserved, and R, is R2, Fig. 1 shows a device for implementing the proposed method; in fig. 2 is an example of an implementation of an arithmetic subtraction unit,

The device consists of a light source 1, the luminous flux from which is directed at an angle to the plane of the object (for example, a printed circuit board 2), the first 3 and second 4 photodetectors (photodetectors contain signal amplifiers), an arithmetic subtraction unit 5, inputs 6 and 7, exit 8.

A device that implements the proposed method works as follows

The light flux from the light source 1 is angled at an object (for example, a printed circuit board 2). The reflected light flux is simultaneously recorded by the first 3 and second 4 photodetectors. The first 3 photodetectors are located on the axis of the directional reflection from the conductor of the printed circuit board.

at a distance R, from the latter, the second photodetector 4 registers only a diffusely reflected flux at a distance R,

The signals from the first 3 and second 4 photodetectors simultaneously arrive at the arithmetic subtraction unit 5, where the signal of the second photodetector 4 is subtracted from the signal 10

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448362

la of the first photodetector 3, and the result is fed to the output of the arithmetic subtraction unit 5 with preservation of the result sign. In the case of reflection of the light flux from the conductor of the printed circuit board to the second photodetector 4, the directional reflected light flux does not enter and the output of the arithmetic imitation unit 5 is a signal corresponding to the illumination of the first photodetector 3, reflecting from the dielectric surface the spots on the printed circuit board are several orders of magnitude shorter than the distances R and R; before the illuminated surface of the first 3 and second 4 photodetectors, the illumination created on the surface of the photodetectors is determined by the formula C "C

 3

where C

i 1

y ri

  FI

(

R-, lightning of a light spot on a printed circuit board; distance from the source to the first 3 photodetector; the distance from the source to the second 4 photodetector.

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Since R RO is EJ E, and

five

At the output of arithmetic subtraction unit 5, an inverse signal from the dielectric with respect to the signal from the conductor appears, and the contrast is determined by the difference between the larger signal and the smaller inverse signal. The increase in contrast depends on the lighting characteristics of the reflective materials and the distances R ,,

So, for example, the signal from the conductive surface on the first photodetector (3) Ef is 10 conventional units, the signal from the dielectric surface on the first photodetector (3) is

2 uel oed., With K - - to, and registration

2. f | And

the signal from the conductive surface at the output of the arithmetic subtraction unit will be Ens-EPZ EP, since E О O due to the absence of illumination of the second photodetector 4. When a light spot hits a dielectric, the reflected light flux register both photodetectors, due to diffuse reflection on: the output of block 5 arithmetic subtraction p | 1ven

, 4- Е - 9- 13 HJ R 4. ,,

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DS

 Eee- 334-4 9 -5.

Therefore, the contrast is

KI 15 ed

CPG-ELU 10 - (-5)

Contrast Enhance Limits

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KI

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The lower boundary of K, is determined when R2 tends to R,. The upper boundary of K is determined by the possible reduction of Rj in real cases. The distance R depends on the geometrical dimensions of the selected photodetectors, i.e. the photodetector 4 should not vignet a reflected light beam that falls on the first photodetector 3; moreover, Kj depends on the lighting characteristics of reflective materials,

The arithmetic subtraction unit 5 contains two inputs 6 and 7, output 8 and contains operational usi0

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Claims (1)

element 9 and resistors 10–13 Arithmetic subtraction unit 5 can be both analog and digital executions The method of separating the boundary of a flat object, which consists in scanning the object with a light beam and detecting the reflected directional light flux, characterized in that, in order to increase the sensitivity when clicking the boundary of the image of a flat object, the reflected diffuse light flux recorded directional light flux is produced at a distance R from the object, and the reflected diffuse light flux at a distance Rj from the volume kta, while f l and by exceeding the threshold level, the result of the subtraction of the signal registered at the distance of the signal registered at the distance R, determines the presence of the boundary of the object 0e. i Phys .2