Liquid purification or separation – With alarm – indicator – register – recorder – signal or...
Reexamination Certificate
2000-06-26
2001-10-23
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
C340S607000, C210S094000, C210S138000
Reexamination Certificate
active
06306290
ABSTRACT:
TECHNICAL FIELD
The present invention relates to indicators in general. More specifically to a timed indicator that shows when a water filter is to be replaced in an apparatus that uses a filter for purifying water.
BACKGROUND ART
Previously, many types of indicators have been used in endeavoring to provide an effective means to monitor and indicate that a water filter is near or at the end of its useful life and needs to be replaced.
A cursory search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however Kurth et al. in U.S. Pat No. 5,188,727 teaches a water filter unit that has a pair of change water filter indicators, one for each filter cartridge, consisting of discs mounted on a post which are marked in months and years and may be set manually when the filters are changed. The indicators are mounted behind the cover with only the pre-set month and year visible from the outside.
U.S. Pat. No. 5,190,643 issued to Duncan et al. is for a portable water treatment device which uses a vessel with a replaceable filter cartridge inside. A lid has an aperture that communicates with the filter and a gate member that is reciprocally movable between a position closing the aperture in the housing and a position opening the aperture. In the open position water is poured into the filter cartridge through the aperture. An indicator moves one increment during a cyclic movement of the gate member which is limited to a predetermined number of increments preventing further movement when the filter needs to be changed.
Boldt Jr. et al. in U.S. Pat. No. 5,328,597 disclose an electronic unit for monitoring the number of uses of a filter cartridge. This unit is self contained and may be attached to any device that incorporates a water filter. A programmed integrated circuit uses different audio input signals to detect each use of the device and monitors when the device is operational and when the end of the life of the filter is eminent. The integrated circuit is programmed to operate a transducer to produce output signals during each use of the device informing the user that the device is operational, that the predetermined end of the filters useful life is eminent or that its life has expired. The unit includes a battery for supplying power to the transducer and integrated circuit and signals are visualized by light emitting diodes.
Parise in the recently issued U.S. Pat. No. 6,024,867 teaches a counter top water filter unit that includes a carbon particle filter cartridge for filtration. A replaceable electronic display monitor unit is mounted in an outlet housing fitted to the top of the cylindrical filter housing. The state of the life span of the filter cartridge is shown on the display monitor in terms of colored indicator lights which denote whether the filter cartridge is within, nearing an end or outside its expected life span. A green light indicates that the cartridge is in its usable life, a yellow light indicates it is about to reach its predetermined life span and a red light designates that the life span has been reached. The electronic circuit detects the time it takes for a ball to flow through a flow channel that is an integral part of the water flow circuitry thereby comparing this lapsed time to the equivalent amount of water passing through the filter. The solid state circuitry translates this information to the volume of water filtered which determines the life expectancy of the filter cartridge.
Other prior art, common to water pitchers with filters utilize floats and mechanical gears to slide a radial indicator a given direction each time the vessel is filled to its nominal level indicating that the filter should be changed when a pointer has completed its travel.
DISCLOSURE OF THE INVENTION
The life expectancy of a conventional filter cartridge used for potable water is based on two separate principles first the amount of contaminants that are absorbed by the media in the filter itself which is determined by its physical size along with the actual absorption capacity of the specific material. Activated carbon is the most common substance used as the media and removes organic material, chlorine and suspended solids usually as small as 5 microns. Normally when the media has absorbed its limit and the pressure differential through the filter increases the capacity of the filter has been reached. When the filter is saturated the water flow declines and slows down which is important particularly in a gravity feed system.
The second principle of life expectancy is actually the time that the filter is exposed to water because the water supply, in almost all city's, contain a certain amount of bacteria, viruses and other micro-organisms. Since organic matter collected in the filter may serve as a nutrient for the bacteria, in time the micro-organisms multiply contaminating the water. The filter manufactures warn against leaving the filter in place too long therefore time limits are recommended and warnings imposed.
A primary object of the invention is to circumvent this problem by taking the latter approach and warn the user that the time has elapsed and the filter should be changed since it may be obvious, due to the slowing of the operational sequence, that the filter was full of unwanted organic matter etc. It would therefore be prudent, in this matter, to protect the user as a first priority and use elapsed time as the governing factor. Therefore the invention incorporates visual indication of the time that the filter has been in place by using a solid state timing circuit in conjunction with indicating lights. This indication assures to the user that the unit, to which the filter is a part, is safe to use and exactly when changing is necessary. Since logic and colors well known to the public are the most reasonable type of warning, a green light indicates that the filter is operating within its usable life, a yellow light indicates it is about to reach its predetermined life span and a red light designates that it is time for replacement.
An important object of the invention is that the time duration may be altered when a larger capacity filter is used which may lengthen the time span for the green light. This feature is easily accomplished in the preferred embodiment by simply removing a jumper from a connector which places another resistor of a different value in the circuit.
Another object of the invention is that reliability is increased which affects the device in which the invention is connected to or integrally formed. Further, when the filters are not changed on a timely basis, chemicals such as lime etc. may build up and cause a malfunction of the entire unit or at the least a slow down of its functional operation when water is fed by gravity.
Still another object of the invention is that the water filter replacement indicator may be incorporated into existing equipment or it may be a separate device that is added at a later time to an existing device as a detached element. If the invention is built in it may share the same electronic circuit and even the same mounting surface for the indicator lights. As an example if the apparatus is incorporated into a commercial coffee brewer the solid state circuit may be included on the same printed circuit board also share the same power supply.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4310828 (1982-01-01), Baker
patent: 4851818 (1989-07-01), Brown et al.
patent: 5089144 (1992-02-01), Ozkahyaoglu et al.
patent: 5188727 (1993-02-01), Kurth et al.
patent: 5190643 (1993-03-01), Duncan et al.
patent: 5328597 (1994-07-01), Boldt, Jr. et al.
patent: 5540107 (1996-07-01), Silverman et al.
patent: 5676824 (1997-10-01), Jeon et al.
patent: 5935426 (1999-08-01), Giordano et al.
patent: 6024867 (2000-02-01), Parise
patent: 6093313 (2000-07-01), Bovaird et al.
paten
Anderson Gordon K.
Cecil Terry K.
Drodge Joseph W.
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