Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-04-30
2001-05-01
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S832000, C029S843000, C174S016300
Reexamination Certificate
active
06223430
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to automatic breadmakers, and more particularly to devices, assemblies, and methods for mounting electronics within automatic breadmakers.
BACKGROUND OF THE INVENTION
As a result of the continuing commercial demand for automatic breadmakers and the resulting market competitiveness between breadmaker manufacturers, increasing emphasis has been placed upon improvements in virtually every aspect of breadmaker design, assembly, and operation. This is particularly evident with respect to breadmaker controls and circuitry. A controls or circuitry improvement which saves seconds in breadmaker assembly or which provides a more reliable or safer breadmaker design can significantly affect a breadmaker's success in the marketplace.
Conventional control and power circuit assembly represents a large percentage of time required to produce a breadmaker. Typically, such circuitry comprises a circuit board which controls high-voltage power supply and distribution (e.g., to such elements as a heater, fan, or kneading member motor) as well as the lower-voltage elements and electronics commonly used in various breadmaking processes (e.g., a microprocessor, control panel, or temperature sensor). The process of installing conventional circuit boards and related circuitry is usually fairly time consuming, and requires the assembler to secure the board within the breadmaker, run leads to and from the elements in the breadmaker, and connect the leads to their respective locations on the board. Because these labor intensive and time consuming tasks are commonly performed by hand, they add substantial cost to the breadmaker.
Conventional breadmakers typically do not optimally locate electronic components, thereby also significantly increasing the cost and decreasing the reliability of the breadmaker. Often, the location of the breadmaker circuit board is distant from the electrical components to which it is connected. For example, where the circuit board is located proximate to a control panel or other user interface, leads must be run from the control panel to connect to breadmaker parts such as the heater, fan, motor, and temperature sensor. Where multiple circuit boards are used, such as in breadmakers having a power supply board and an electronic controls circuit board, even more leads must be run. The parts and material costs resulting from these connections have a significant impact upon the breadmaker cost.
Apart from the cost of wiring circuit boards which are distant from their connected elements, other problems can arise as a result of such designs. Specifically, voltage drops between the circuit boards and their connected electronic elements are possible. Also, longer leads are more susceptible to electronic noise from the breadmaker motor or from a source external to the breadmaker. Especially in the case of temperature control devices, voltage drops and electronic noise can compromise breadmaking operations and result in poor breadmaker performance.
Yet another problem with conventional breadmakers arises where the same circuit board is used both for high-voltage power supply and distribution and for lower-voltage elements and electronics (see above). Lower-voltage elements and electronics in breadmakers are usually located near or are connected to a user interface such as a control panel. Most conventional breadmakers also mount high voltage circuitry near the user interface, typically mounting all major electronic components on the same board. Short circuits or other electrical malfunctions can endanger the users of a breadmaker employing such a design.
In light of the shortcomings of the prior art and in light of the design requirements and limitations described above, a need exists for a breadmaker apparatus and method which minimizes the time necessary to assemble the electronics in breadmakers, lowers the parts and labor costs associated with breadmaker electronics and installation, lessens system susceptibility to voltage drops and electronic noise, and which provides a safer breadmaker design. Each preferred embodiment of the present invention achieves one or more of these results.
SUMMARY OF THE INVENTION
The breadmaker of the present invention has a baking oven casing at least partly defining a baking chamber within which bread is baked, an interior wall separating the baking chamber from a component compartment and a circuit board located within the component compartment and coupled to the interior wall. At least one thermal control device, such as a temperature sensor, a thermistor, a thermal fuse, or the like, is connected to the circuit board and is preferably held upon the surface of the interior wall. In a preferred embodiment of the present invention, the circuit board is coupled to the interior wall by a component mounting bracket which maintains the thermal control device in heat transfer relationship with the interior wall. Also in a preferred embodiment, the circuit board is a high voltage power board, and is electrically coupled to a lower voltage power board. The high voltage power board preferably supplies power to various breadmaker components such as the motor, heating element and fan. The low voltage power board preferably controls the operations of the breadmaker and includes a timer, microprocessor and related circuitry. The low voltage power board is preferably electrically coupled to a control panel accessible by a user to operate the breadmaker. Low power electrical signals are generated and conducted between the low voltage power board and the high voltage power board, thereby increasing device safety.
The present invention further provides a method for mounting a circuit board assembly in a breadmaker having an oven casing and an interior wall as described above. At least one thermal control device is preferably mounted upon a circuit board. The circuit board is coupled to an interior surface of the breadmaker to mount the thermal control device in heat transfer relationship with the interior surface. Preferably, the circuit board is coupled to the interior wall via a component mounting bracket. More preferably, the thermal control device is a thermostat, thermistor or a thermal fuse held against the interior wall by the component mounting bracket. The circuit board is preferably a high voltage circuit board and a preferred method of the present invention includes the step of connecting the high voltage circuit board to a low voltage circuit board which controls breadmaker operations.
The present invention simplifies assembly of the breadmaker electronics by reducing the number of connections which must be made by the assembler when installing the circuit boards. For example, because the thermal control devices are preferably held by the component mounting bracket against the interior wall of the breadmaker, wires need not be run from the circuit board to the necessary locations in the breadmaker. Indeed, the circuit board of the present invention can be manufactured with the thermal control devices already connected to the circuit board. This facilitates easy installation and hookup of the circuit board within the breadmaker, and saves a significant amount of parts and labor cost. Because less wiring is used, the system is less susceptible to poor performance due to electronic noise and/or voltage drops, particularly with thermal control devices directly connected to the circuit board rather than connected thereto via conventional leads. Where two circuit boards (i.e., a high voltage circuit board connected via low voltage lines to a low voltage circuit board) are used in the most preferred embodiment of the present invention, safer operation of the breadmaker is provided by keeping high voltage elements away from the user interface.
More information and a better understanding of the present invention can be achieved by reference to the following drawings and detailed description.
REFERENCES:
patent: 4395133 (1983-07-01), Clevenholm et al.
patent: 4762057 (1988-08-01), Hirota et al.
patent: 48672
Myszka Robert V.
Utzerath James H.
Vancha John
Arbes Carl J.
Michael & Best & Friedrich LLP
Premark WB Holdings, Inc.
Trinh Minh
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