Control marking detector

• US 4,392,056 A
• Filed: 04/27/1981
• Issued: 07/05/1983
• Est. Priority Date: 04/27/1981
• Status: Expired due to Term

• Current Assignee: Automated Packaging Systems Incorporated (Sealed Air)
• Original Assignee: Automated Packaging Systems Incorporated (Sealed Air)
• Inventors: Weyandt, Ronald R.
• Primary Examiner(s): Willis, Davis L.
• Application Number:
  US06/253,193
• Time in Patent Office: 799 Days
• Field of Search: 250/339, 250/458.1, 250/459.1, 250/461.1, 250/223 R, 250/548, 250/567, 235/468, 235/476
• US Class Current: 250/339.11
• CPC Class Codes: B65H 23/046 Sensing longitudinal register of web B65H23/18 takes precedence

Abstract

A detector 10 used to sense the presence of control markings 20 on a moving web 12. The detector responds to abrupt changes in intensity of electromagnetic radiation rather than merely to absolute intensity values. Gradual changes in or a constant level of detected radiation or detector temperature do not change the magnitude of the abrupt changes in radiation intensity to which the detector responds. This capability allows the detector to distinguish between electromagnetic radiation emitted by wavelength-shifting control marks 20 and changes in web background and/or ambient radiation. A filter 38 is interposed between a photo diode 36 in the detector 10 and the web 12 to further enhance detector performance.

Claims

1. Apparatus for detecting the presence of indicia affixed to an article of manufacture to coordinate an article control function with article movement comprising:

(a) radiation responsive means mounted near a web path of travel to detect radiation from the indicia;

(b) level detection means having a first input coupled to said radiation responsive means and a second input feedback coupled to a detection means output to provide a bias input which causes the detection means output to change appreciably only in response to abrupt changes of radiation intensity from the web; and

(c) means for sensing changes in said detection means output and for providing a control signal to initiate the control function.

2. The detector of claim 1 which further comprises a filter interposed between the web and the radiation responsive means to attenuate radiation of certain wavelengths while letting other wavelengths pass substantially unattenuated to the radiation responsive means.

3. The detector of claim 1 wherein the feedback coupling between the amplifiers second input and the amplifier output comprises voltage storage device for causing the voltage at the second input to follow the voltage at the first input for slowly varying changes in the first input voltage.

4. The detector of claim 1 or 3 wherein the radiation responsive means is sensitive only to radiation wavelengths in the infra red range.

5. The detector of claim 1 or 3 wherein the radiation responsive means is sensitive only to radiation wavelengths in the visible range.

6. A detector for sensing the presence of a mark on an article moving relatively to the detector comprising:

(a) radiation responsive means for sensing radiation intensity;

(b) means to illuminate said article with radiation of a wavelength that causes said mark to emit wavelength shifted radiation;

(c) filter means interposed between said article and said radiation responsive means to attenuate radiation other than radiation of the same wavelength as the wavelength shifted radiation; and

(d) circuitry coupled to said radiation responsive means to generate a control output in response to abrupt changes in wavelength shifted radiation intensity as sensed by said radiation responsive means;

said output being indicative of the presence of a mark on the article.

9. The detector of claim 6, 7 or 8 wherein the wavelength of said illuminating radiation and the shifted wavelength of the emitted radiation are both in the infra red range.

10. The detector of claim 6, 7 or 8 wherein the wavelength of said illuminating radiation is in the ultraviolet range and the shifted wavelength of the emitted radiation is in the visible range.

7. A detector for sensing the presence of a mark on an article moving relatively to the detector comprising:

(a) radiation responsive means for sensing radiation intensity;

(b) means for mounting said radiation responsive means in relation to an article path of travel;

(c) means coupled to said means for mounting to illuminate said article with radiation of a wavelength which causes said mark to emit wavelength shifted radiation;

(d) filter means interposed between said article and said radiation responsive means to attenuate radiation other than radiation of the same wavelength as the wavelength shifted radiation; and

(e) circuitry coupled to said radiation responsive means to generate a control output in response to abrupt changes in wavelength shifted radiation intensity as sensed by said radiation responsive means;

said output being indicative of the presence of a mark on the article.

8. The detector of claim 7 wherein said circuitry comprises difference means having a first input coupled to the radiation responsive means and a second input feedback coupled to an output through an energy storage device to provide a variable bias input to said difference means.

11. A detector for sensing the presence of a mark on an article moving relatively to the detector comprising:

(a) radiation responsive means for sensing radiation intensity;

(b) means to illuminate said article with radiation of a wavelength which causes said mark to emit wavelength shifted radiation;

(c) filter means interposed between said article and said radiation responsive means to attenuate radiation other than radiation of the same wavelength as the wavelength shifted radiation; and

(d) circuitry coupled to said radiation responsive means to generate a control output in response to abrupt changes of predetermined magnitude in radiation intensity and to inhibit gradual changes in or a constant level of detected radiation from significantly contributing to or detracting from the predetermined magnitude;

said output being indicative of the presence of a mark on the article.

12. A detector for sensing the presence of a mark on an article moving relatively to the detector comprising:

(a) radiation responsive means for sensing radiation intensity, said means also being responsive to temperature changes;

(b) means to illuminate said article with radiation of a wavelength which causes said mark to emit wavelength shifted radiation;

(c) filter means interposed between said article and said radiation responsive means to attenuate radiation other than radiation of the same wavelength as the wavelength shifted radiation; and

(d) circuitry coupled to said radiation responsive means to generate a control output in response to abrupt changes of predetermined magnitude in radiation intensity, said circuitry including elements inhibiting gradual changes in or a constant level of temperature of the radiation responsive means from significantly contributing to or detracting from the predetermined magnitude;

said output being indicative of the presence of a mark on the article.

13. In a method of sensing the presence of a mark on an article moving relatively to a detector, said mark having the capability of emitting radiation of a wavelength shifted from that of certain radiation directed upon the work, the steps comprising:

(a) illuminating the article with radiation of a wavelength that causes said mark to emit wavelength shifted radiation;

(b) attenuating radiation from said article and mark that is of different wavelength from the wavelength shifted radiation;

(c) detecting radiation of said shifted wavelength; and

(d) generating a control output only in response to abrupt changes of predetermined mangitude in the detected radiation, said control output being indicative of the presence of a mark on the article.

14. In a method of sensing the presence of a mark on an article moving relatively to a detector, said mark having the capability of emitting radiation of a wavelength shifted from that of certain radiation directed upon the work, the steps comprising:

(a) illuminating the article with radiation of a wavelength that causes said mark to emit wavelength shifted radiation;

(b) attenuating radiation from said article and mark that is of different wavelength from the wavelength shifted radiation;

(c) detecting radiation of said shifted wavelength; and

(d) generating a control output only in response to abrupt changes of predetermined magnitude in the detected radiation while inhibiting gradual changes in or a constant level of detected radiation from significantly contributing to or detracting from the predetermined magnitude, said control output being indicative of the presence of a mark on the article.