Detecting stretch or shrink in print media
A printing system includes a print media and one or more non-objectionable test patterns formed or printed on the print media. An integrated imaging system captures images of the one or more non-objectionable test patterns. The integrated imaging system includes a housing, an opening in the housing for receiving light reflected from a moving print media, a folded optical assembly in the housing that receives the reflected light and transmits the light a predetermined distance, and an image sensor within the housing that receives the light and captures one or more images of the one or more non-objectionable test patterns. A processing device can process the one or more images to determine if one or more size variations have occurred in the print media.
1. A printing system comprising:
a print media;
one or more non-objectionable test patterns formed or printed on the print media;
an integrated imaging system, comprising:
a housing;
an opening in the housing for receiving light reflected from the moving print media;
a folded optical assembly in the housing that receives the reflected light and transmits the light a predetermined distance; and
an image sensor within the housing that receives the light and captures one or more images of the one or more non-objectionable test patterns;
a storage device for storing one or more reference test pattern signals; and
a processor for producing a test pattern signal for each of the one or more non-objectionable test patterns formed or printed on the print media, for comparing each test pattern signal to a respective one of the one or more reference test pattern signals to determine whether a size variation has occurred in the print media, for determining compensation values in response to the size variation in the print media, and for using the compensation values to adjust the operational settings for the printing system.
2. The printing system as in claim 1 , further comprising at least two vent openings in the housing, one vent opening for inputting air or gas and one vent opening for outputting exhaust.
3. The printing system as in claim 1 , further comprising a light source for emitting light towards the print media.
4. The printing system as in claim 1 , further comprising a roller for transporting the print media through the printing system.
5. The printing system as in claim 4 , further comprising a motion encoder connected to the roller, wherein the motion encoder is adapted to output a signal proportional to a fixed amount of incremental motion of the print media.
6. The printing system as in claim 4 , wherein the integrated imaging system is disposed over the print media at a location where the print media is transported over the roller.
7. The printing system as in claim 1 , further comprising a vent opening in the housing for receiving air or gas.
8. The printing system as in claim 7 , wherein the opening in the housing is used to output exhaust.