JPH04223206A - Method for processing sensor signal by ccd element - Google Patents

Abstract

PURPOSE:To obtain a binary-coded signal which is stable for a long time by holding a peak-level voltage of a light source, resetting it, performing A/D conversion and then feeding it to a microcomputer, calculating a value of a specific % of an input value and then setting it as a slice level. CONSTITUTION:A band-shaped object 1 is allowed to run between a light source 3 and a CCD element sensor 2 and an obtained 'bright' or 'dark' video signal A is binary-coded by a slide level signal for judgment. A peak-level voltage VP in the 'bright' level is held by a peak-hold circuit 5, is A/D converted by an A/D converter 6, is reset by a reset circuit 7, and a digital signal D1 with a voltage of VP is led into a microcomputer 8. A slide level voltage VS is calculated in a microcomputer 8 based on the voltage VP and 50-80% of the voltage VP is output as a digital signal D2. Video signal is processed by a comparator 10 in reference to a voltage VS which is obtained by performing D/A conversion of this signal D2 and is taken out as a binary-coded signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing sensor signals using a CCD element (electronic camera) for measuring the position or width of a strip of paper, cloth, nonwoven fabric, steel plate, or the like.

0002

[Prior Art] Various methods are known for detecting the edge position and measuring the width dimension of the various strips mentioned above.
A typical example is a method using a fluorescent lamp light source and a CCD element.

[0003] This method uses a CCD element above both edges of a strip of material that is being transported, such as cloth that is being transported for inspection or printing, and a fluorescent lamp (hereinafter referred to as a light source) below. A CCD element images the "dark" part where part of the light from the light source projected from the bottom to the top is blocked by the fabric, and the "bright" part where it is directly illuminated without being blocked. The video signal is processed and extracted as a binary signal, and the "dark" part and the "
It reads the light intensity change point with the "bright" part, converts the signal into a numerical value using a controller, and displays the edge position and width of the cloth.

0004

[Problems to be Solved by the Invention] By the way, the amount of light from a light source fluctuates depending on factors such as the time of use and ambient temperature, and when the amount of light fluctuates, the video signal level of the "bright" portion captured by the CCD element changes. If the slice level falls below the slice level set for determining "bright" and "dark," or conversely, the video signal in the "dark" area exceeds the slice level, making it impossible to extract the binarized signal. In reality, the slice level voltage is adjusted every time such a situation occurs. Such a situation often occurs in the case of cloth, nonwoven fabric, paper, film, etc., which have different light transmittances depending on the type.

[0005] The present invention improves the inconvenience caused by variations in the light intensity of a light source, and obtains a binary signal that is stable for a long period of time without requiring adjustment of the slice level voltage each time even if the light intensity changes. The purpose is to

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention holds and resets the peak level voltage (maximum light amount in the "bright" portion) of the light source during actual operation, and also A/D level signal
Convert to microcomputer (hereinafter referred to as microcomputer)
50 to 80 of this input value on the microcontroller.
% value and use this discount value as the slice level.

That is, a strip is run between a fluorescent lamp light source and a CCD element, and a "bright" signal level obtained by direct radiation from the light source and a "bright" signal level obtained by being blocked by the strip are determined. When making a binarization judgment based on the slide level of a waveform signal with a "dark" signal level, "bright"
The peak level voltage of the signal is held in the peak hold circuit, and the peak level voltage is A/D converted and reset, and then input to the microcomputer and set in the range of 50 to 80%, which is preset and stored in the microcomputer. The ratio is multiplied by the peak level value, the value is determined as the slice level voltage, this slice level value is D/A converted, and the comparator corrects it based on this D/A converted value, and the binary value is determined. It is designed to be extracted as a conversion signal.

It is desirable that the above-mentioned holding and resetting of the peak level voltage be carried out at regular intervals, and the peak level voltage at that period be A/D converted and input to the microcomputer.

Further, the value of the slice level voltage calculated by the microcomputer is determined in advance as a ratio to the peak level voltage in consideration of the light transmittance of the strip, and the ratio is preferably about 50 to 80%. Around 80% for high transmittance, 50% for low transmittance
% is practical.

0010

[Operation] While constantly monitoring the light intensity level of the video signal, the light source is Always displays stable binary data even when changes in light intensity occur.

[0011]

[Embodiment] Hereinafter, an embodiment of the present invention will be explained based on the attached drawings, which schematically show the following. Fig. 1 shows the basic configuration for measuring the position and width of a strip-like object. CCD element sensors 2, 2 are disposed, and fluorescent lamp light sources 3, 3 are disposed on both sides below the strip-shaped object 1, facing the CCD element sensors 2, 2.
The strip 1 is transferred between the two, and the video signal from the CCD element sensor 2 is processed by a digital controller 4.

FIG. 2 is a block diagram of signal processing in the controller 4, and FIG. 3 shows a timing chart of FIG.

According to the present invention, the strip 1 is run between the light source 3 and the CCD sensor 2, and the video signal A of the CCD sensor 2, that is, the video signal A obtained by direct radiation from the light source 3, is When the waveform signal is binarized and determined using the slice level signal B, the "bright" signal level A1 and the "dark" signal level A2 obtained by being blocked by the strip 1 are determined. The peak level voltage Vp of A1 is held by the peak hold circuit 5, and the peak level voltage Vp of A1 is held by the converter 6.
/D conversion and reset by the reset circuit 7, the digital signal D1 of the peak level voltage Vp is introduced into the microcomputer 8. The microcomputer 8 stores in advance a setting that the slide level voltage Vs is 50% of the input peak level voltage Vp.

Therefore, based on the input peak level voltage Vp value, the microcomputer 8 calculates the slide level Vs value, and calculates the value of the slide level Vs by 50% of the peak level voltage Vp.
A value of /100 is output as a digital signal D2, this digital signal is D/A converted by a converter 9, this value is set as a slice level voltage Vs, and a video signal is processed by a comparator 10 using this slice level voltage Vs as a reference. The signal is then extracted as a binary signal (D).

[0015]

Effects of the Invention According to the method for processing the video signal A from the CCD element sensor of the present invention as described above, as shown in FIG. Even if a voltage Vd appears, or even if the peak level voltage Vp of the light amount of the light source 3 decreases, Vp>Vs>V
The state d is reliably maintained, and a binary signal as shown in FIG. 3(b) can be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a simplified diagram showing the basic configuration of a measuring section for measuring the position and width of a strip.

FIG. 2 is a block diagram of signal processing in a controller.

FIG. 3 is a timing chart of signal processing.

[Explanation of symbols]

1　Striped material 2 CCD element 3 Light source 4 Controller 5 Peak hold circuit 6 A/D converter 7 Reset circuit 8. Microcomputer 9 D/A converter 10 Comparator A Video signal A1 "Bright" signal level A2 "Dark" signal level Vp Peak level voltage Vs slice level voltage B Slice level

Claims (1)

[Claims] [Claim 1] A fluorescent lamp light source and a C that outputs a video signal.
A "bright" signal level A1 obtained by running a strip between the CD element sensor and direct radiation from the light source;
When making a binary value judgment of the waveform signal due to the "dark" signal level A2 obtained by being blocked by the band-shaped object at the slice level B, the peak level voltage Vp of the "bright" signal level is determined by a peak hold circuit. At the same time, the peak level voltage Vp is A/D converted and reset, then input to the microcomputer 8, and the computer multiplies it by a preset ratio within the range of 50 to 80% of the peak level value. The calculated value is output as a slice level signal D2, this slice level signal D2 is D/A converted, and the comparator 10 is converted based on the slice level B of this D/A converted value Vs.
A method of processing a sensor signal using a CCD element, characterized in that the signal is output as a binary signal D.