“A hot air display cabinet with two fans, one for driving hot air over food items via openings in a duct, the other for forming an air curtain across an open front and for drawing air from the top part of the compartment where the food is stored.”
“…one fan for controlling the air curtain circuit and another fan to control the food-warming circuit.”
“The pump [which I interpose is the lower pump] draws air through the front perforated sheet and into the inlet. The air is then blown by the pump through the outlet over heating elements through the perforations in the adjacent part of the perforated skin and into the air duct. The heated air is driven upwards through the duct and the upper end of the duct as the closure of the heated air is forced through the perforations then the front skin of the door and into the chambers indicated by arrows.”
“The operation of the fan [I interpose the upper fan] draws some of the air near the top of the chamber upwards, thereby encouraging airflow at the top of the chamber beneficial for maintaining the temperature of food packs on the top shelf and through perforations in the sheet which are immediately beneath the fan. The fan forces air into the compartment and through the outlet. The air driven through the outlet and past the fins is forced downwards and slightly inwards by virtue of the inclination of the fins. The air entering the compartment through the perforations in the skin has a component of outward movement towards the open front of the chamber.”
“need to create a) a flow of hot air over all the food packages … throughout … and then through the top … and b) an independent air flow system (emphasis added) to produce an air curtain”
“Heated air is driven upwards by a fan and hence into a tapered annular gap defined by a perforated cylinder and an adjustable cone device. Thus some of the air passes under pressure through the perforations, to heat the food items that are displayed on the shelves as shown in the drawing. The rest of the air passes up into a gap between two hemispherical domes and hence downwards to form the air curtain.”
“He might be looking for an apparatus that would merely keep food warm”, which is part of what Guibert taught. He continued: “He might not need to pack his food items at all tightly.”
“…it did not occur to Guibert to use one fan for controlling the air curtain circuit and another fan to control the food-warming circuit.”
“The air curtains are driven by [two] fans. When the back door of the cabinet is closed air passes up the back of the cabinet through a pair of vertical flues … when the back door is opened this air continues to rise acting as an air curtain the flues are in open and direct communication with the spaces between the shelves of the cabinet.”
“I will assume that the person skilled in the art who read Detwiler in 1998 was interested in designing a display cabinet for keeping food hot.”
“The open front of the flue does not have a guarantee that a sufficient amount of cooled air will reach the food stored at the top of the cabinet or that the flow of air would be reasonably even throughout. Moreover any food overhanging the back of the shelves so as to project into the cabinet will interfere with and upset the flow of air along the flue [sic]. Moreover a flow path to the second blower does not encourage air to blow over food at the other end of the cabinet, so no even air flow or air in the top of the chamber, which is what the specification of the patent claimed to reveal over Detwiler.”
“the second flow inducing means being arranged to draw air from the upper end of the chamber and use it in the formation of an air curtain across the open front of the chamber.”