Automatic flusher with bi-modal sensitivity pattern

Details Automatic flusher with bi-modal sensitivity pattern Automatic flusher with bi-modal sensitivity pattern

1999-09-07

2001-04-10

Huson, Gregory L. (Department: 3751)

Baths, closets, sinks, and spittoons

Flush closet

Urinals only

C004S304000, C004S305000, C004S406000, C250S221000, C250S216000

Reexamination Certificate

active

06212697

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention concerns automatic flush systems and is directed particularly to sensor apparatus that they employ.
Technological advances in recent years have made the use of automatic flushers quite popular in public facilities. Although they have been employed for both toilets and urinals, their use for urinals has been much more widely accepted than for toilets, because automatic urinal flush systems have tended to be more reliable than automatic toilet flush systems.
One reason why toilet flushers tend to be less reliable is that toilets tend to be placed in stalls. This requires the object detectors on whose operation automatic flushers are based to distinguish between actual users and stall surfaces. Although ways of making this distinction exist, they tend to be relatively complicated, costly, and inconvenient.
SUMMARY OF THE INVENTION
We have found that the difficulty presented by such enclosures can be greatly reduced by employing a sensor system that in plan view has a bimodal sensitivity pattern. Specifically, the sensor is significantly less sensitive in a central region, where the sensor radiation's angle of incidence on a stall door is more nearly normal, than immediately to that region's left and right, where it is less so. This tends to reduce responsiveness to enclosure surfaces in comparison with user surfaces. The reason for this result appears to be that surfaces such as those of stall doors tend to reflect more specularly than those of the desired target, namely, the user. This means that the stall door reflects less light back to the source than a user does when the incident light forms a large angle with the surface normal. This feature is particularly beneficial if the sensor's sensitivity-pattern maxima that flank the central region are spaced apart in front of the toilet bowl by an amount that matches the spacing of a typical user's legs, which are the sensor's typical targets.
Another aspect of the present invention takes further advantage of the tendency of enclosure surfaces to be more specular than user surfaces. According to this aspect of the invention, the sensor system's sensitivity pattern is directed at a downward angle rather than horizontally. This, too, tends to result in angles of incidence that differ significantly from perpendicular and therefore produce relatively little retroreflection from surfaces that reflect somewhat specularly.
A further reason for this aspect's advantage seems to be that it reduces the sensor's sensitivity to motions of a user seated on the toilet. Since the sensor pattern is directed at a downward angle, the sensor tends to respond less to the user's upper back, which tends to move most, and more to the user's lower back, which tends not to move as much.
We have found that employing such directional sensitivity patterns greatly reduces the difficulties of implementing automatic flush systems in enclosed environments.


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