Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
2000-03-07
2001-08-07
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C250S349000, C250S221000, C250S577000, C250S230000, C250S231130
Reexamination Certificate
active
06271523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the present invention relate to a sensor apparatus, system and process for monitoring the passage of a mechanical device or a target object such as, in preferred embodiments, the motion of a rotating sweep hand indicator of a consumables meter. In preferred embodiments, the consumables meter comprises a sweep hand meter of the type including, but not limited to a water meter, a gas meter, an electric meter or the like.
2. Description of Related Art
The usage of certain consumable materials is often measured and displayed by a sweep hand meter, such as a conventional water meter, gas meter or electricity meter. Utility meters are typically monitored periodically by service personnel (a meter reader) of the respective utility company. Such monitoring practices have typically required utility company personnel to physically visit the location of the utility meter and observe the information recorded by one or more sweep hands of the meter. In many cases, these utility meters are installed within the premise of each household, business, or the like, and are often located at a distance from the public street, or within a gated area where access to the utility meters is encumbered. As a result, such conventional meter reading practices can be problematic, time-inefficient and, in some cases, dangerous for the meter reader.
To address such problems as described above, utility meters with a remote meter reading systems have been developed. A remote meter reading system allows a meter reader to read one or more utility meters from a remote location, thus avoiding the need for a meter reader to enter the premises or location of each utility meter. The remote meter reading system thus improves the efficiency in reading the utility meters and provides the utility company personnel with a safer working environment. However, conventional remote meter reading systems typically require the replacement of conventional utility meters with a monitoring/transmitting device designed to monitor the particular consumable and to transmit consumption readings to a remote location. Such replacement devices can be costly and the installation of such devices may require special electrical, plumbing or mechanical skills.
Another difficulty encountered with prior attempts to remotely read utility meters arises from the fact that the types and manufacturers of utility meters can vary from one household to another household, from one city block to another or from one county to another. Furthermore, utility meters are installed in a variety of diversified environments. For example, the utility meters may be constantly exposed to extremely high or low ambient temperature, or they may be installed outdoors under bright sun light or within a dark enclosed area. Therefore, a system designed for one type of meter or environment of use may not be satisfactory for other meter types or environments.
SUMMARY OF THE DISCLOSURE
It is an object of embodiments of the present invention to provide a remote meter reading system that addresses the above-referenced problems.
It is an object of further embodiments of the present invention to provide such a remote meter reading system that includes apparatus that is readily installed on a conventional utility meter having a sweep hand indicator or a meter needle, without requiring internal modifications of the meter.
It is another object of embodiments of the present invention to provide a sensor system and a method for detecting the motion of a rotating sweep hand indicator of a meter without modifying the internal composition of the meter. In one feature of preferred embodiments of the present invention, a sensor system is easily field installed onto and operated with a wide spectrum of utility meters of different styles from different manufactures under diversified environmental conditions and provides a non-intrusive way to monitor the operation of the utility meters.
It is still another object of the present invention to provide a photo sensor apparatus and an optical sensing method that provides an accurate reading of a utility meter under a variety of background illumination conditions that vary, for example, depending on the position of the sun and other sources of light. In accordance with one embodiment of the present invention, a photo sensor apparatus is attached to a utility meter having a sweep hand indicator which moves adjacent a background surface. The photo sensor apparatus includes one photo emitter, such as an infrared emitter, and at least one, and preferably two photo detectors. In a preferred embodiment, the emitter is positioned to illuminate a portion of the background surface passed by the sweep hand during its motion, to provide a shadow of the sweep hand on the background surface as the sweep hand moves through the illuminated portion. Also, the photo detectors are positioned at an angle with respect to the emitter and define at least one, and preferably two viewing fields on the illuminated portion of the background surface to detect the shadow of the sweep hand indicator of the utility meter as the sweep hand indicator passes through the illuminated portion. In further preferred embodiments, the photo detectors detect changes in the intensity of light reflected on the sweep hand indicator and the background surface as well as the shadow of the sweep hand indicator.
In accordance with further preferred embodiments of the present invention, a photo sensor apparatus, such as described above, includes a single infrared emitter and two photo diodes for detecting infrared light irradiated by the infrared emitter and reflected on the surface of the utility meter on two separated viewing fields. In accordance with one embodiment, the photo diodes are electrically coupled in series and are reversed-biased by a direct current signal. As a result, with respect to the node between the two photo diodes, currents through the two photo diodes cancel each other out when the two diodes are exposed to about equal amounts of light, for example, during the portion of the sweep hand motion in which the sweep hand indicator of the utility meter does not intercept either of the two separated fields. However, when currents through the two photo diodes are unbalanced by the presence of the sweep hand indicator in one of the two fields, the difference is amplified and used as a detection signal for comparison to a threshold value. In further preferred embodiments, as the sweep hand passes through both fields, two oppositely directed difference signal amplitude pulses are generated and compared with two respective threshold values.
In a further preferred embodiment, the light source is positioned at an angle with respect to the background surface and the detector(s), to illuminate the sweep hand from an angle. Since the sweep hand normally passes just above the background surface of the meter face, illuminating from an angle allows the optical detector(s) to observe the passing sweep hand indicator immediately followed by or immediately after its shadow region. If the sweep hand indicator is more reflective than the background surface, the presence of the sweep hand followed by (or after) the sweep hand shadow in a viewing field of a photo diode results in the photo diode generating two oppositely directed amplitude pulses which may be used as a detection signal for comparison with one or two threshold values. Alternatively, in embodiments in which the two photo diodes are coupled in opposite directions to provide a difference amplitude signal, the passage of a sweep hand shadow in the viewing field of one of the photo diodes, followed by the passage of the sweep hand in the viewing field of the other photo diode, provides a difference signal having two oppositely directed amplitude pulses, which may be compared with two respective threshold values.
A method of sensing motion of a sweep hand indicator of a meter which moves above a background surface, in accordance with one embodiment of the present inventi
Moman Gary
Weaver John D.
Foley & Lardner
Hannaher Constantine
Israel Andrew
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