Device for checking envelopes for enclosed documents
First Claim
1. In a device for checking a plurality of generally rectangular envelopes for enclosed documents, the combination comprising:
- means for feeding said envelopes one at a time past an inspection station at a substantially constant velocity with each of said envelopes being oriented so that two of its edges are leading and trailing edges, respectively, both perpendicular to its direction of movement and its remaining two edges are parallel to said direction of movement, and a detection means at said inspection station, said detection means comprising first, second and third opacity sensors spaced from one another along a line generally parallel to the plane of said envelopes and perpendicular to said direction of envelope movement and each producing an electrical output signal which varies with the opacity of an associated discrete sensed field, said three opacity sensors being arranged so that as said envelopes are moved past said inspection station the field sensed by said first sensor is located inboard of one of said two remaining edges of each envelope, said field sensed by said second sensor is located inboard of the other of said remaining edges of each envelope, and said field sensed by said third sensor is located between said fields of said first and second sensors, and suspect signal producing means responsive to the existence for a predetermined time of a substantial difference in the values of the output signals of said first and third opacity sensors or of the output signals of said second and third opacity sensors for producing a suspect signal indicating the suspected presence of a document in the envelope producing such suspect signal.
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Accused Products
Abstract
A device for checking supposedly emptied envelopes for documents, as the envelopes are fed in spaced end-to-end relationship past an inspection station, consists of three sensors at the inspection station arranged along a line perpendicular to the envelope path to sense the opacity of each envelope along three zones located respectively near the top, near the bottom and near the center of the envelope. The output of the center sensor serves as a reference for the top and bottom sensors and a signal processing circuit connected with the sensors produces a suspect signal, indicating the suspected presence of a document in an envelope, when the output of either the top or bottom sensor compares unfavorably with that of the center sensor for an amount of time sufficient to make the device insensitive to short duration opacity differences caused by overlapping envelope seams. Since the center sensor provides a reference signal for each individual envelope, the device is insensitive to changes in opacity from envelope to envelope due to differences in the papers from which the envelopes are made. Further, the output of the center sensor is also compared with a predetermined reference signal to detect unusually wide documents which intercept the sensing fields of all three sensors. A gate mechanism operable in response to the production or non-production of a suspect signal as each envelope passes the inspection station segregates envelopes suspected of containing documents from those not so suspected.
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Citations
12 Claims
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1. In a device for checking a plurality of generally rectangular envelopes for enclosed documents, the combination comprising:
- means for feeding said envelopes one at a time past an inspection station at a substantially constant velocity with each of said envelopes being oriented so that two of its edges are leading and trailing edges, respectively, both perpendicular to its direction of movement and its remaining two edges are parallel to said direction of movement, and a detection means at said inspection station, said detection means comprising first, second and third opacity sensors spaced from one another along a line generally parallel to the plane of said envelopes and perpendicular to said direction of envelope movement and each producing an electrical output signal which varies with the opacity of an associated discrete sensed field, said three opacity sensors being arranged so that as said envelopes are moved past said inspection station the field sensed by said first sensor is located inboard of one of said two remaining edges of each envelope, said field sensed by said second sensor is located inboard of the other of said remaining edges of each envelope, and said field sensed by said third sensor is located between said fields of said first and second sensors, and suspect signal producing means responsive to the existence for a predetermined time of a substantial difference in the values of the output signals of said first and third opacity sensors or of the output signals of said second and third opacity sensors for producing a suspect signal indicating the suspected presence of a document in the envelope producing such suspect signal.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
Specification