Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1996-12-18
1998-08-18
Glick, Edward J.
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
2503411, 15DIG15, G01N 2188, G01N 2101
Patent
active
057961069
DESCRIPTION:
BRIEF SUMMARY
This invention concerns a detector for detecting the build up of water, frost or ice on a surface.
BACKGROUND OF THE INVENTION
The invention will be described by way of example with reference to use of the device to detect frost or ice formation within a refrigerator to control a defrost cycle in such a refrigerator. It should be appreciated that this is by way of example only and that the device of the invention may also be used in other applications. For example the device of the invention may be employed in detecting the formation of ice on windows, windscreens, aircraft wings and in controlling de-icing.
In no frost or frost free refrigerators a defrost cycle is periodically initiated to defrost the refrigerator to eliminate or minimise the build up of ice. Manufacturers of refrigerators currently determine defrost cycles for refrigerators by conducting tests in particular hot and humid climates and as a result of those tests preset defrost cycle requirements for refrigerators for all climatic conditions up to and including the conditions experienced at the test locality. This means that for locations where climatic conditions are not as severe, defrosting occurs more often than necessary and energy is wasted.
Timed defrost cycles are employed where a heating element of a capacity of about 500 W is energised for twenty-five minutes at a time about two or three times per day. Thus defrosting occurs regardless of whether there is any frost or ice build up in the refrigerator. It is desirable to complete the defrost cycle as quickly as possible so that the effects that opening of the refrigerator door have on the defrost cycle are minimised. Thus, a particularly large power capacity heating coil is employed to achieve defrosting.
No attempt is presently made to detect the presence of frost or ice and to initiate a defrost cycle only when frost or ice is present. Rather, heating to effect defrosting occurs for set time periods and a set number of times per day.
It is an object of the present invention to provide a detector which may be used to control a defrost cycle in a refrigerator which at least minimises the disadvantages referred to above.
DISCLOSURE OF THE INVENTION
According to one aspect, the invention provides a detector for detecting the presence of ice, water, frost or other solids and discriminating between the presence of solids and liquids, the detector including: a sensing surface provided by a medium substantially transparent to electromagnetic radiation and upon which solids or liquids may be deposited, a radiation transmitter for directing radiation onto the medium from a side of the medium opposed to the sensing surface, a radiation receiver receiving radiation reflected from the surface and a discriminator circuit operable in response to an output from the receiver to discriminate between the presence of liquids or solids on the surface and providing an output indicative of whether a solid or a liquid is present on the surface.
The electromagnetic radiation may be visible light, Infra-Red, Ultra-Violet or any other suitable radiation. Preferably Infra-Red radiation of a wavelength of 930 nm is employed. Where I-R radiation is used, the transmitter may comprise an I-R diode and the receiver an I-R photo transistor. Preferably, a reflective switch such as that manufactured by Honeywell and identified by the device code HOA-1397-2 or equivalent or substitute is used.
The medium which provides the sensing surface, as mentioned, is substantially transparent to the radiation employed. Glass or a plastics material such as acrylic or perspex may be used. Preferably glass is used. The sensing surface may be a partial mirror surface or a clear surface. Alternatively, the surface is frosted, patterned, grooved (dimples or ripples) or sandblasted or may be a combination of clear and frosted, patterned, grooved or sandblasted surface finishes. A normally clear surface allows most of the radiation impinging upon it to pass through and reflects only a small percentage of incident radiation. The
REFERENCES:
patent: 3947131 (1976-03-01), Karl
patent: 4620141 (1986-10-01), McCumber et al.
patent: 5414257 (1995-05-01), Stanton
LandOfFree
Ice and liquid detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ice and liquid detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ice and liquid detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1116632