Importance

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Abstract

A control device for a multi-zone conveyor oven constructed according to the present invention comprises a microprocessor-based controller, appropriate control software, a keyboard and display for interaction with a user, means for sensing the conveyor speed and the heating chamber temperature, and means for controlling the power supplied to the conveyor motor and the heating elements. The controller provides facilities for user programming of sets of oven parameters, each set corresponding to a particular food product to be cooked in the oven. Each set of parameters includes the total cook time for the product and a desired temperature which is independently selectable for each heating zone. Once a set of parameters has been programmed, it is assigned to a particular key on the keyboard, and the user may select that entire set of parameters by simply pushing the assigned key. The parameters are stored in the EEPROM to prevent their loss during electrical power interruptions. High-accuracy, low hysteresis temperature control of the oven is provided by pulse-width-modulating the power supplied to the heating elements. Accurate and repeatable control of cooking time is provided by controlling the speed of the motor driving the product transport conveyor. Such control is provided by pulse-width-modulating the power supplied to the motor according to motor speed information derived by sensing the motor shaft position. The controller also provides extensive fault detection, and degrades oven performance as gracefully as possible.

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First Claim