摘要:
@ Apparatus for detecting missing areas or folded corners in sheets, for example banknotes (14), is disclosed. Figure 1 shows a banknote (14) being scanned in a strip along one edge of the banknote. A strip light source (12) and a strip sensor (16) are disposed on opposite faces of the banknote which is caused to move perpendicularly to the light path between the source and sensor, and perpendicularly to the plane of the drawing. A photometer (18) responds to the total amount of light transmitted through the edge strip of the banknote (14) as the banknote is scanned. A filter (20) may be inter posed in the light path to improve the sensitivity of the apparatus. The total amount of transmitted light detected by the photometer (18) is integrated over a period of the scan during which the intensity differs substantially from the mean level for an unflawed portion of the banknote. Integration is thus performed only over missing or folded areas of the banknote. It may also be limited to only the leading and trailing portions of the edge strip of the banknote, corresponding to the corners of the note. In order to compensate for the passage of a skewed banknote passing through the apparatus, integration is inhibited over the said period whenever the intensity waveform from the photometer (18) is steeper than a predetermined gradient.
摘要:
Apparatus is disclosed for scanning a banknote (33). A lengthwise strip of the banknote (33) is illuminated with white light, and the banknote is moved parallel to its width. Light reflected from all regions of the lenghtwise strip is conveyed through an optical fibre fishtail array to a single photodetector, or to a spectroscope and thence to several photodetectors for colour scanning. The waveform produced by the or each photodetector is then characteristic of the surface of the banknote, and is used in an analysing circuit for banknote pattern recognition, or to sense the condition of the banknote with regard to its age or degree of soiling. The analysing circuit includes means for compressing or expanding the lenght of the waveform to give it a standard lenght for subsequent comparison with one or more stored characteristic waveforms in a memory (16). The apparatus also determines the mean level of intensity of the waveform in an integrator (9), and includes a circuit (24 to 28) for obtaining the standard deviation of selected points of the waveform from the mean value, a low standard deviation indicating a badly soiled or worn banknote.
摘要:
@ Apparatus for detecting missing areas or folded corners in sheets, for example banknotes (14), is disclosed. Figure 1 shows a banknote (14) being scanned in a strip along one edge of the banknote. A strip light source (12) and a strip sensor (16) are disposed on opposite faces of the banknote which is caused to move perpendicularly to the light path between the source and sensor, and perpendicularly to the plane of the drawing. A photometer (18) responds to the total amount of light transmitted through the edge strip of the banknote (14) as the banknote is scanned. A filter (20) may be inter posed in the light path to improve the sensitivity of the apparatus. The total amount of transmitted light detected by the photometer (18) is integrated over a period of the scan during which the intensity differs substantially from the mean level for an unflawed portion of the banknote. Integration is thus performed only over missing or folded areas of the banknote. It may also be limited to only the leading and trailing portions of the edge strip of the banknote, corresponding to the corners of the note. In order to compensate for the passage of a skewed banknote passing through the apparatus, integration is inhibited over the said period whenever the intensity waveform from the photometer (18) is steeper than a predetermined gradient.
摘要:
Apparatus is disclosed for scanning a banknote (33). A lengthwise strip of the banknote (33) is illuminated with white light, and the banknote is moved parallel to its width. Light reflected from all regions of the lenghtwise strip is conveyed through an optical fibre fishtail array to a single photodetector, or to a spectroscope and thence to several photodetectors for colour scanning. The waveform produced by the or each photodetector is then characteristic of the surface of the banknote, and is used in an analysing circuit for banknote pattern recognition, or to sense the condition of the banknote with regard to its age or degree of soiling. The analysing circuit includes means for compressing or expanding the lenght of the waveform to give it a standard lenght for subsequent comparison with one or more stored characteristic waveforms in a memory (16). The apparatus also determines the mean level of intensity of the waveform in an integrator (9), and includes a circuit (24 to 28) for obtaining the standard deviation of selected points of the waveform from the mean value, a low standard deviation indicating a badly soiled or worn banknote.