Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1997-05-20
1998-06-16
Le, Que
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
2502221, 194318, G01V 904
Patent
active
057675066
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an optical coin sensing station and has particular but not exclusive application to sensing coins leaving the outlet port of a coin hopper.
BACKGROUND
Optical coin sensors have been used for coin hoppers and coin validators in order to detect the presence of coins travelling along a coin passageway. Conventionally, an optical source such as a light emitting diode (LED) directs a beam of light across the coin passageway to a photosensor such as a photodiode. Interruption of the beam by a coin travelling along the passageway is detected by sensor circuitry connected to the photodiode, so as to indicate the presence of a coin. In many situations, coins of different diameters travel along the same passageway and a single source-detector pair will not necessarily detect all coin diameters reliably. Additionally, problems arise with coins that contain holes, which give rise to spurious results from conventional detectors. In order to overcome these problems, hitherto, it has been proposed to use more than one source-detector pair spaced apart across the width of the passageway. However, this increases the component count for the sensor and adds to its expense.
In EP-A-0 017 428 (Mars Inc) there is described an optical sensor in which a beam from a source is arranged to cross a coin passageway on a first occurrence and is the reflected back to a sensor, on the same side of the passageway as the source. Thus, the beam crosses the passageway at two spaced apart locations, which increases reliability of detection for coins of different diameter. However, with this arrangement, significant problems remain. For example, the beam crossings for the passageway need to be arranged in pairs which does not necessarily conveniently fit the geometrical arrangement of the coin hopper or coin validator. In some situations, the most efficient detecting arrangement includes an odd number of sensing locations across the width of the channel; this cannot be achieved by means of the prior art configuration of EP-A-0 017 428. Furthermore, the optical source needs to be directly facing the major surfaces of the coin whereas, in practice, there may not be sufficient room in the coin hopper or validator to accommodate this configuration.
SUMMARY OF THE INVENTION
The present invention provides a solution to these problems. In accordance with the invention, there is provided an optical coin sensing station comprising means defining a passageway along which coins can pass edgewise, a source for providing a source beam of optical radiation, beam splitting means for providing first and second sensing beams from the source beam, means for directing the sensing beams to traverse the passageway at spaced apart locations, first and second sensor means for respectively detecting the first and second sensing beams after having traversed the passageway, whereby the passage of at least one of the sensing beams to its respective sensor means is interrupted by the major surfaces of a coin passing along the passageway, and means responsive to outputs from the sensor means to detect the presence of a coin.
Thus, in accordance with the invention, by the use of a beam splitting means, it is possible to direct the first and second sensing beams from a single source beam, across the passageway at different, spaced apart locations.
In a preferred embodiment, a second source is provided with a second beam splitting means, and a third sensor is provided spaced from the first and second sensors. The second beam splitting means forms third and fourth sensing beams, the third sensing beam being directed to the third sensor, whereas the fourth sensing beam is directed to the second sensor. All three sensors may receive light of substantially similar intensity levels.
The output means conveniently comprises an OR circuit so that an indication of the presence of a coin in the passageway is provided when any one of the sensing beams is interrupted.
The sensing station conveniently is formed in a housing formed o
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Coin Controls Ltd.
Le Que
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