Control marking detector

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.

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.

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.

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.

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.

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.