EP0168202A1
Expired / Lapsed
EP
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Method and apparatus for monitoring sheets
Assignee: De la Rue Systems Ltd
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Filing: 1985-06-27
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Granted: —
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Expires: 2005-06-27
Abstract
Abstract A method and apparatus for monitoring the passage of sheets past at least one sensing assembly (48, 49). The sensing assembly (48,49) generates an output signal whose level varies in accordance with a characteristic of the sheets, for example the thickness of the sheets. The method comprises for the or each sensing assembly, presetting a first threshold (62) spaced by a predetermined amount from a datum output signal level (57) when no sheet is sensed, the predetermined amount being such that the first threshold (62) is not passed as a result of random noise variations in the output signal but is passed during the passage past the sensing means of all sheets which it is desired to monitor. The size of the output signal from the sensing means (48,49) relative to the datum level is monitored when the output signal first passes the first threshold (62) corresponding to the passage of a first sheet. Single, double, and triple sheet thresholds (63, 64, 67) are generated from a monitored size and thereafter the output signal is monitored to sense when it passes one or more of the thresholds.
Inventors
- 👤 David Robert Worsley
- 👤 Roy Eric Winchester
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 07:02
CPC Classifications
B; B65; B65H; B65H7/00; B65H7/02; B65H7/14; B65H43/00; B65H43/08; B65H2404/00; B65H2404/10; B65H2404/14; B65H2511/00; B65H2511/10; B65H2511/17; B65H2511/50; B65H2511/51; B65H2553/00; B65H2553/40; B65H2553/41; B65H2553/412; B65H2701/00; B65H2701/10; B65H2701/19; B65H2701/1912
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
217 words
A method of monitoring the passage of sheets (59) past at least one sheet sensing assembly (15,18) of a sheet feeding apparatus, the or each sensing assembly (15,18) generating an output signal whose level varies in accordance with a characteristic of the sheets, the method comprising for the or each sensing assembly (15,18) setting a single sheet output signal threshold (63) at a level which will be passed by the output signal generated by the sensing assembly when a sheet passes the sensing assembly; and monitoring the output signal at least when it passes the threshold (63) characterised by presetting a first threshold (62) spaced by a predetermined amount from a datum output signal level (57) achieved when no sheet is sensed, the predetermined amount being such that the first threshold (62) is not passed as a result of random noise variations in the output signal but is passed during the passage past the sensing assembly of all sheets which it is desired to monitor; monitoring the size of the output signal relative to the datum level (57) when the output signal first passes the first threshold (62) corresponding to the passage of a first sheet; generating the single sheet threshold (63) from the monitored size; and thereafter sensing when the output signal passes the thresholds (62,63).
Claim 2
Independent Claim
217 words
A method of monitoring the passage of sheets (59) past at least one sheet sensing assembly (15,18) of a sheet feeding apparatus, the or each sensing assembly (15,18) generating an output signal whose level varies in accordance with a characteristic of the sheets, the method comprising for the or each sensing assembly (15,18) setting a single sheet output signal threshold (63) at a level which will be passed by the output signal generated by the sensing assembly when a sheet passes the sensing assembly; and monitoring the output signal at least when it passes the threshold (63) characterised by presetting a first threshold (62) spaced by a predetermined amount from a datum output signal level (57) achieved when no sheet is sensed, the predetermined amount being such that the first threshold (62) is not passed as a result of random noise variations in the output signal but is passed during the passage past the sensing assembly of all sheets which it is desired to monitor; monitoring the size of the output signal relative to the datum level (57) when the output signal first passes the first threshold (62) corresponding to the passage of a first sheet; generating the single sheet threshold (63) from the monitored size; and thereafter sensing when the output signal passes the thresholds (62,63).
Claim 3
Dependent Claim
28 words
A method according to claim 1, further comprising generating an error signal if the output signal passes the first threshold (62) but not the single sheet threshold (63).
Claim 4
Dependent Claim
48 words
A method according to claim 1 or claim 2, further comprising generating a double sheet threshold (64) from the monitored size, the level of the output signal from the or each sensing assembly passing the double sheet threshold (64) during the passage of two or more overlapped sheets.
Claim 5
Independent Claim
44 words
A method according to any of the preceding claims, further comprising generating a triple sheet threshold (67) from the monitored size, the output signal level from the sensing assembly passing the triple sheet threshold (67) during the passage of three or more overlapped sheets.
Claim 6
Dependent Claim
23 words
A method according to claim 4, further comprising generating an error signal if the output signal level passes the triple sheet threshold (67).
Claim 7
Dependent Claim
41 words
A method according to claim 4, when dependent on claim 3, comprising detecting the passage of two overlapped sheets when the output signal level from the sensing assembly passes the double sheet threshold (64) but not the triple sheet threshold (67).
Claim 8
Independent Claim
26 words
A method according to any of the preceding claims, wherein the output signal of the sensing assembly varies in accordance with the thickness of the sheets.
Claim 9
Independent Claim
22 words
A method according to any of the preceding claims, further comprising monitoring the length of sheets passing the or each sensing assembly.
Claim 10
Dependent Claim
41 words
A method according to claim 8, wherein the sheets are moved at a substantially constant speed past the or each sensing assembly, the step of monitoring the length comprising monitoring the time for which the single sheet threshold (63) is passed.
Claim 11
Dependent Claim
37 words
A method according to claim 8 or claim 9, further comprising generating an error signal if the monitored length of a sheet varies significantly from the monitored length of the first sheet fed past the sensing assembly.
Claim 12
Independent Claim
44 words
A method according to any of the preceding claims, in which two sensing assembies are provided laterally spaced across a feed path of the sheets, the method comprising monitoring the output signals from each sensing assembly to detect the passage of incorrectly fed sheets.
Claim 13
Dependent Claim
214 words
Apparatus for monitoring the passage of sheets (59) past at least one sensing assembly (15,18), the sensing assembly being adapted to generate an output signal whose level varies in accordance with a characteristic of the sheets, the apparatus comprising storage means (54) for storing for the or each sensing assembly a single sheet output signal threshold (63) corresponding to a signal level which will be passed by the output signal generated by the sensing assembly when a sheet passes the sensing assembly; monitoring means (52,53) for monitoring the output signal; means (54) for storing a first, preset threshold (62) spaced by a predetermined amount from a datum output signal level (57) achieved when no sheet is sensed, the predetermined amount being such that the first threshold is not passed as a result of random noise variations in the output signal but is passed during the passage past the sensing assembly of all sheets which it is desired to monitor, the monitoring means (52,53) being adapted to monitor the size of the output signal relative to the datum level (57) when it first passes the first threshold (62); and calculating means (53) for calculating the single sheet threshold (63) from the monitored size and for storing the single sheet threshold in the storage means (54)-.
Claim 14
Dependent Claim
214 words
Apparatus for monitoring the passage of sheets (59) past at least one sensing assembly (15,18), the sensing assembly being adapted to generate an output signal whose level varies in accordance with a characteristic of the sheets, the apparatus comprising storage means (54) for storing for the or each sensing assembly a single sheet output signal threshold (63) corresponding to a signal level which will be passed by the output signal generated by the sensing assembly when a sheet passes the sensing assembly; monitoring means (52,53) for monitoring the output signal; means (54) for storing a first, preset threshold (62) spaced by a predetermined amount from a datum output signal level (57) achieved when no sheet is sensed, the predetermined amount being such that the first threshold is not passed as a result of random noise variations in the output signal but is passed during the passage past the sensing assembly of all sheets which it is desired to monitor, the monitoring means (52,53) being adapted to monitor the size of the output signal relative to the datum level (57) when it first passes the first threshold (62); and calculating means (53) for calculating the single sheet threshold (63) from the monitored size and for storing the single sheet threshold in the storage means (54)-.
References Cited (Backward Citations)
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