Method for detecting films
First Claim
1. A method for detecting a film of a printing liquid on a surface in a printing machine, comprising the steps of:
- irradiating the surface with light over an illumination beam path for producing a reflection of light over a reception beam path at a Brewster angle with respect to the normal of the surface;
at least partially polarizing the light in the incident plane in at least one of the two beam paths;
receiving the light reflected from the surface over the reception beam path;
evaluating the intensity of the received light at the receptor; and
determining the presence of the film when a substantial absence of light is detected by comparing the evaluated intensity of light to a predetermined threshold value.
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Accused Products
Abstract
The invention relates to a method and device for detecting ink or lacquer films on metallic surfaces inside printing machines. In particular, to irradiate the surface with light and sensing of the intensity of the reflected light to detect whether an ink film or lacquer film on a roller has been completely removed by applying a metering element or doctor-blade element. This is achieved according to the invention by the irradiation of the metallic surface or of the film located thereon, and the reception of the light reflected from the surface or the film located thereon is performed at the Brewster angle with respect to the surface normal, the Brewster angle being defined by the refractive index of the material of the film to be determined and that liner polarization of the light is performed at least partially in the plane of incidence, at least in one of the two beam paths.
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Citations
14 Claims
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1. A method for detecting a film of a printing liquid on a surface in a printing machine, comprising the steps of:
- irradiating the surface with light over an illumination beam path for producing a reflection of light over a reception beam path at a Brewster angle with respect to the normal of the surface;
at least partially polarizing the light in the incident plane in at least one of the two beam paths;
receiving the light reflected from the surface over the reception beam path;
evaluating the intensity of the received light at the receptor; and
determining the presence of the film when a substantial absence of light is detected by comparing the evaluated intensity of light to a predetermined threshold value. - View Dependent Claims (2, 3, 4, 5)
- irradiating the surface with light over an illumination beam path for producing a reflection of light over a reception beam path at a Brewster angle with respect to the normal of the surface;
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6. A device for detecting a film of a printing liquid on a surface in a printing machine, comprising:
- an illumination source for irradiating the surface with light over an illumination beam path at the Brewster angle with respect to the surface normal;
a receptor for receiving the light reflected from the surface over a reception beam path at the Brewster angle with respect to the surface normal;
at least one polarization filter situated in at least one of the two beam paths for partial linear polarization of the light in the incident plane; and
a light intensity evaluating circuit for evaluating the intensity of the light received at the receptor indicating the presence of the film of the printing liquid when a substantial absence of light is detected as determined by the intensity of light falling below a predetermined threshold value. - View Dependent Claims (7, 8, 9, 10, 11)
- an illumination source for irradiating the surface with light over an illumination beam path at the Brewster angle with respect to the surface normal;
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12. A method for detecting a film of a printing liquid on a surface in a printing machine, comprising the steps of:
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irradiating the surface with light over an illumination beam path for producing a reflecting of light over a reception beam path at a Brewster angle with respect to the normal of the surface; at least partially polarizing the light in the incident plane in the reception beam path; receiving the light reflected from the surface over the reception beam path; evaluating the intensity of the received light at the receptor; and determining the presence of the film by comparing the evaluated intensity of light to a predetermined threshold value. - View Dependent Claims (13, 14)
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Specification