Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
1999-04-19
2001-01-23
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S303200, C219S407000, C236S002000, C237S003000, C600S022000
Reexamination Certificate
active
06177271
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to laboratory incubators, and more particularly to a laboratory incubator having an improved temperature control assembly that more effectively maintains the temperature within the incubator in a desired range and that more accurately controls the rate of heat loss from the incubator as ambient temperatures rise.
2. Description of the Prior Art
The temperature within a laboratory incubator must be maintained within a certain operating temperature range that is typically above ambient temperatures. Therefore, it is common to provide laboratory incubators with heating devices that are periodically cycled to maintain the temperature within the interior of the incubators in this range. Heaters can effectively maintain the temperature within a desired range as long as the ambient temperature around the incubator is substantially lower then the desired operating range. However, when the ambient temperature increases so that it approaches the desired operating temperature of the incubator, the rate of heat loss through the walls of the incubator decreases so that excess heat from the chamber does not dissipate therefrom. Typically, if ambient temperatures rise to within 5° C. of the incubator's desired operating temperature, the internal temperature within the incubation chamber begins to rise at the same rate of change as the ambient temperature, causing the temperature within the incubator to rise above its desired operating range.
Prior art attempts to solve this problem include the placement of a jacket of cooling liquid or refrigerant around an incubator. When the ambient temperature rises to a certain high level, the liquid in the jacket is cooled by cooling coils to increase the incubator's heat loss so that the temperature within the incubator can be more easily maintained in a desired range. These prior art cooling devices are impractical and sometimes ineffective, however, because they are expensive, bulky, and difficult to control.
Therefore, there is a need for a laboratory incubator having an improved temperature control assembly for more accurately maintaining the operating temperature within the incubator in a desired operating range and for maintaining a minimum heat loss rate from the incubator as the ambient temperature around the incubator rises.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention solves the above-described problems and provides a distinct advance in the art of laboratory incubators. More particularly, the present invention provides a laboratory incubator having an improved temperature control assembly that more effectively maintains the temperature within the incubator in a desired range and that more accurately controls the rate of heat loss from the incubator as ambient temperatures rise.
The incubator of the present invention broadly includes a housing having an enclosed incubation chamber therein; a heater positioned within the housing for heating the chamber; a cooling device positioned within the housing for cooling the chamber; and a controller for controlling the operation of the heater and the cooling device to maintain the temperature in the chamber within a desired temperature range. In accordance with one aspect of the invention, the cooling device is an electrically operated peltier device operable to both cool the chamber and to assist the heater in heating the chamber.
In operation, the controller cycles the heater whenever the ambient temperature is significantly lower than the desired operating temperature of the incubator to maintain the operating temperature of the incubator within a desired range. Then, if the ambient temperature approaches the operating temperature of the incubator, the controller cycles the peltier device to cool the walls of the incubator for increasing the rate of heat loss from the interior of the incubator to the walls. This allows excess heat within the incubator to dissipate through the walls of the incubator to prevent the incubator's temperature from rising above the desired operating range.
The peltier device is less expensive, easier to install, and easier to control than prior art cooling devices used in incubators. Moreover, the peltier device is also operable for heating the walls of the incubator for decreasing the heat loss from the chamber to assist the heater in maintaining the temperature within the incubator when the ambient temperature outside the incubator is significantly below the desired operating temperature within the incubator. Thus, unlike prior art cooling jackets, the peltier device can be controlled to either increase or decrease the heat loss through the walls of the incubator.
REFERENCES:
patent: 5281516 (1994-01-01), Stapleton et al.
patent: 5783439 (1998-07-01), Reichler et al.
Butts Charles G.
Runion Timothy R.
Hovey Williams Timmons & Collins
Redding David A.
SPX Corporation
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