Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reissue Patent
2000-09-15
2003-03-18
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C315S159000
Reissue Patent
active
RE038036
ABSTRACT:
BACKGROUND
1. Field of Invention
This invention relates to electronic timers and photoelectric controllers used to control electric lighting, activate animal feeders, control irrigation, or other timed control activation apparatus, where daylight sensing is used as a timing cue.
2. Discussion of Prior Art
Electric or electronic timer apparatus often used for controlling devices need to be set with the proper time, both initially and upon replacing a battery or after the time wanders for some reason. In some applications, having to set the time could require that personnel reach inaccessible places.
Another class of device controllers operates on sensing daylight. Where timing is based relative to the amount of ambient daylight, these prior art device controllers do not employ an internal time clock. They rely upon the natural cycle of the day and night. The driving function of these controllers, after all, is the amount of light, not the absolute time.
Photoelectric controls have long been used to sense daylight and activate a switch based upon the amount of light intensity measured by the photoelectric ‘eye’. Streetlights and other outdoor lighting have been controlled by employing low-cost circuits. The photoelectric light controls save energy by only activating the lamps when it is dark. Furthermore, it occurs automatically and does not require human intervention.
In the application of prior art utilized for outdoor lighting, there are some disadvantages to the way these controls function. The controls in such lighting employ a delay function so that the lamp is less likely to be falsely started. This works sufficiently well, much of the time. It still occurs that a lamp will be activated when a stormy cloudcover forms temporarily. This occasional occurrence with old methods has an associated cost, and this is a disadvantage of the prior art.
Because of the cost of energy and cost of wear-and-tear on the lamp every time a lamp is started unnecessarily, the cost can be significant over time. For yard lighting, the photoelectric controls are often used with one controller on each lamp in the yard. Since changing the lightbulb may require the utilization of a ladder, the homeowner would appreciate the advantage of increasing the life of the bulb.
Photoelectric controls have also long been used in animal feeder devices. A simple circuit detects light intensity and triggers a motor to run when the light intensity increases over a given threshold, at sunrise. The motor causes feed to be distributed on the ground for game to eat. Similarly at sunset, detection of the decrease in light intensity below a threshold triggers a feeding by activating the feed motor. The prior art typically uses, at most, only three functions:
a. measurement of ambient light intensity;
b. measurement of the rate of change of ambient light intensity;
c. time delay (on the order of time less than one hour).
One disadvantage of this method is that occasionally the feeder will be triggered in response to light intensity changes due to clouds rolling by. This disrupts the feeding pattern, wastes food, and lessens battery life. Another disadvantage is that it is desirable to feed the game before the sun goes down, while there is still ample hunting light. To trigger the feeder based on light intensity alone or change in light intensity, it is impossible to get the circuit to consistently feed a fixed time before the sun goes down. By introducing time delay in the circuit to attempt to reduce the occurrence of false triggers, this results in the sundown feeding occurring after dark. To the hunter, this is a disadvantage.
Sometimes another time delay function is added. There have been some attempts in prior art to cause an animal feeder device to feed before sundown. The intention is to encourage a foraging pattern among the game animals such that they are out during times of ample hunting daylight. While it is desirable to feed game about an hour before sundown, the prior art could not effectively accomplish this. The simplistic method employed in the prior art was to start an electronic timer upon sunrise, which caused a feeding to occur a given fixed amount of hours after sunrise when the timer timed-out. The inferior performance of this prior method is exemplified here. Assume employment of a fixed time delay of 9 hours after sunrise. At some latitude, this may cause the afternoon feeding to occur about an hour before sundown in December, but the feeding would occur six hours before sundown in June.
A similar additional time delay has sometimes been added to photoelectric lighting controls. The added function of keeping lights on for a set period of time, after sunset, has been employed. Adding a fixed time delay function is not
affective
effective
in providing the service of activating lights one hour before sunrise, for instance. This is another disadvantage of prior art device controllers. The means of anticipation of the event of sunrise or sunset cannot be performed with methods that, previously, only reacted to sunrise or sunset.
Photoelectric light detection has been available for utilization in
apparatus,
apparatus
for sixty years. Microelectronics
has
have
been available for decades, and the microcontroller has been available for twenty-five years. This invention does not result from material or items that have just very recently become available. Many photoelectric controls used today still use Cadmium Sulfide sensors and bimetallic thermal delay switches. Many other photoelectric controls used today use microelectronics. While some of the prior art applications utilize new technology components, they lack in innovation and novelty, even though their material cost is sufficient to support the methods and construction shown in this invention.
OBJECTS AND ADVANTAGES
My invention employs, among other things, an internal ‘clock’, as an important method of deriving improvement and new function over previously utilized methods. Scheduling events of device activation and deactivation from the ‘clock’ instead of directly off the detection of light is key to the advantages which result.
As a result of the internal ‘clock’, one object is that every sunrise or sunset event does not have to be detected. If the performance of the apparatus does not rely on detection of every sunrise or sunset, the measurement criteria for sunrise or sunset can be increased. Preferably, the method here is to start out with loose criteria for detection, and increase the criteria to a higher level after confidence is secured. Contrasting this concept with prior art: if a sunrise or sunset is not detected, the device activation tied to that event will not be delivered. The tradeoff in the prior art is then to have lower criteria so as to not miss detection of sunrise or sunset. The disadvantage of this is that the prior art, with lower criteria, will trigger activation from false detections, such as cloud activity.
Another object is that events can be scheduled to occur before the detection of sunrise or sunset. Because of the establishment of the internal ‘clock’, the nominal time of the next sunrise or sunset is ‘known’ by the apparatus in the present invention. This is an advantage of this invention, to be able to schedule an activation in anticipation of an event of sunrise or sunset instead of in direct reaction to it. Contrarily, in prior art, anticipation of events could not be implemented.
Apparatuses
Apparatus
of
the
prior art exhibit that the creators of these devices attempted to provide a function of this sort by utilizing a fixed time delay triggered by the direct detection of sunrise or sunset. The fixed time delay does not work because of the mechanics of earth rotation and revolution around the sun.
The earth rotates about
its
an
axis that is tilted 22.5 degrees from being at a right angle to the plane of the earth orbit around the sun. If the earth were not tilted, the seasons would not change and the time for sunrise and sunset would be
the
substantially the same, relative to noon time, a
Allen Stephone B.
Colton, Inc. Wayne J.
Outland Sports, Inc.
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