Isotherm cooking plate apparatus, system, and method of manufacture

An isothermal cooking plate assembly (50) mechanically attached within a griddle system (10) and comprising:

• (a) a first plate (52) of high thermal conductivity material comprising aluminum whose thickness is substantially uniform, having a thermal conductivity of at least 1.67 watts/cm-C, a surface area of not greater than 54 square inches, a length-to-width aspect ratio that does not exceed about 1.5, a thickness in the range of 0.187 to 0.250 inches, and having a back surface (159) and an oppositely disposed top food-cooking surface (28);
• (b) a thick-film printed and fired heater circuit assembly (130) disposed on and substantially covering the first plate back surface (159) and comprising:
• (i) a first glass thick-film printed and fired electrically insulative layer (141) disposed on the first plate back surface (159) having a thickness that does not exceed a maximum allowed thickness, tdielectric of the glass thick-film printed and fired first electrically insulative layer, the maximum allowed thickness, tdielectric corresponding to the maximum allowable thickness of the first electrically insulative layer that avoids the fracture, cracking and/or breaking of the thick-film printed and fired first electrically insulative layer during rapid heat-up of the aluminum first plate, the maximum allowed thickness, tdielectric calculated using the equation (Equation 1H):
• tdielectric=[{σdielectric*(1−μ)}/{αdielectric*Edielectric}]*[kdielectric/{Qheater/Aheater}],
• wherein the calculated maximum allowed value for the thickness, tdielectric Of the glass thick-film printed and fired first electrically insulative layer is based on maximum level of applied heat flux, {Qheater/Aheater} and known thermal conductivity, kdielectric of the glass thick-film printed and fired first electrically insulative layer as well as the known properties of glass including the breaking strength of glass, σdielectric;
• modulus of elasticity, Edielectric coefficient of thermal expansion, αdielectric and Poisson's ratio, μ;
• (ii) third electrically conductive bus strips (132a and 132b) thick film printed onto the previously thick-film printed and fired first surface of first electrically insulative layer;
• (iii) second electrically resistive heating element legs (144a-144r and 145) thick-film printed and fired on previously thick-film printed and fired first surface of first electrically insulative layer and extending onto the previously thick-film printed and fired third electrically conductive bus strips to effect electrical communication between the second electrically resistive heating element legs and the third electrically conductive bus strips;
• and
• (iv) distal ends of first and second electrical leads (158, 160) removably attachable to first and second contact pads (62, 64), respectively, wherein the first and second electrical contact pads are disposed on the third electrically conductive bus strips;
• and
• (c) a controller (20) in electrical communication with the thick-film printed and fired heater circuit assembly through removably attachable first and second electrical leads (158, 160) at first and second contact pads (62, 64), respectively, on the third electrically conductive bus strips, controlling a temperature of the first plate top food-cooking surface using temperature sensor (39) removably attached to first plate;
• the first plate, thick-film printed and fired heater circuit assembly and a second plate (30) combine to form cooking plate assembly (50) wherein:
• (i) the maximum temperature difference between an operator selected set point temperature and any temperature of the first plate top food-cooking surface in contact with food is less than about 10 C for set point temperatures up to about 230 C, and
• (ii) the rate of heat-up of the first plate from about 25 C to about 150 C is less than about 30 seconds using an applied voltage of 115 volts and maximum current of 20 amps for the single heating circuit assembly substantially covering the first plate back surface.