Apparatus for precisely regulating the paraffin temperature in an electrically heated tissue processor

Claim 2

Apparatus for precisely regulating the temperature of paraffin heated in a electrically heated tissue processor comprising: a sensor responsive to the temperature of paraffin heated in the electrically heated tissue processor, said sensor changing from a first conduction state to a second conduction state when the temperature of paraffin heated in the electrically heated tissue processor rises above a predetermined temperature; clamp means for detachably fastening said sensor to the electrically heated tissue processor so that at least a portion of said sensor is immersed in the paraffin heated in the tissue processor; controller means electrically coupled to said sensor and being responsive to the conduction state of said sensor for providing a low impedance circuit path thereacross for alternating current during intervals while said sensor remains in its first conduction state and for providing a high impedance circuit path thereacross for alternating current during intervals while said sensor remains in its second conduction state following a rise in the temperature of paraffin heated in the electrically heated tissue processor above the predetermined temperature; and means coupled to said controller means for detachably coupling said controller means in series with the electrically heated tissue processor across a source of alternating current.

Claim 3

The invention according to claim 1 wherein said sensor comprises a mercury thermostat whose conduction state changes from a normally open circuit to a closed circuit when the temperature of paraffin heated in the electrically heated tissue processor rises above the predetermined temperature.

Claim 4

The invention according to claim 1 wherein said clamp means comprises: a spring circumscribing the outer periphery of said sensor for retaining said sensor; and a "U" shaped clip fastened to said spring for detachable engagement with the electrically heated tissue processor so that at least a portion of said sensor is immersed in the paraffin heated in the electrically heated tissue processor.

Claim 5

The invention according to claim 1 wherein said controller means comprises: a first pair of diodes coupled in series-opposing fashion with the electrically heated tissue processor across a source of alternating current; a second pair of diodes coupled in series opposing fashion, said second pair of diodes being coupled in parallel with said first pair of diodes; a triac having a gate terminal, a first load terminal coupled to the junction between the diodes of said first pair of diodes and a second load terminal coupled to the junction between the diodes of said second pair of diodes; a capacitor coupled between said first load terminal of said triac and said triac gate terminal; a resistor coupled between said triac gate terminal and said second triac load terminal; means for connecting said sensor across said capacitor; a printed circuit board for securing said first and second pair of diodes, said triac, said capacitor and said resistor; and a phenolic block encapsulating said printed circuit board.

Claim 6

The invention according to claim 1 wherein said means for coupling said controller in series with the electrically heated tissue processor across a source of alternating current comprises a plug tap.

Claim 7

In combination with an electrically heated tissue processor configured of a paraffin-containing cavity, a heating element affixed to the underside of the cavity for heating the paraffin contained therein when the heating element is energized with alternating current, a bimetallic thermostatic switch and a line cord having a plug at the end thereof for coupling the heating element and bimetallic switch across a source of alternating current, apparatus for precisely regulating the temperature of paraffin heated in the paraffin-containing cavity by the heating element, said apparatus comprising: a sensor responsive to the temperature of paraffin heated in the paraffin-containing cavity by the heating element, said sensor changing conduction states from a first to a second state when the temperature of paraffin in the paraffin-containing cavity rises above a predetermined temperature; clamp means for detachably securing said sensor to paraffin containing cavity so that at least a portion of said sensor is immersed in the paraffin in said paraffin-containing cavity; controller means electrically coupled to said sensor and being responsive to the conduction state of said sensor for providing a low impedance circuit path thereacross for alternating current during intervals while said sensor remains in its first conduction state and for providing a high impedance circuit path thereacross for alternating current during intervals while said sensor remains in its second conduction state following a rise in paraffin temperature above said predetermined temperature; and means coupled to said controller means for detachably coupling said controller means in series with the tissue processor heating element and bimetallic thermostatic switch across a source of alternating current.

Claim 8

In combination with an electrically heated tissue processor configured of a paraffin-containing cavity, a heating element affixed to the underside of the cavity for heating the paraffin contained therein when the heating element is energized with alternating current, a bimetallic thermostatic switch and a line cord having a plug at the end thereof for coupling the heating element and bimetallic switch across a source of alternating current, apparatus for precisely regulating the temperature of paraffin heated in the paraffin-containing cavity by the heating element, said apparatus comprising: a sensor responsive to the temperature of paraffin heated in the paraffin-containing cavity by the heating element, said sensor changing conduction states from a first to a second state when the temperature of paraffin in the paraffin-containing cavity rises above a predetermined temperature; clamp means for detachably securing said sensor to paraffin containing cavity so that at least a portion of said sensor is immersed in the paraffin in said paraffin-containing cavity; controller means electrically coupled to said sensor and being responsive to the conduction state of said sensor for providing a low impedance circuit path thereacross for alternating current during intervals while said sensor remains in its first conduction state and for providing a high impedance circuit path thereacross for alternating current during intervals while said sensor remains in its second conduction state following a rise in paraffin temperature above said predetermined temperature; and means coupled to said controller means for detachably coupling said controller means in series with the tissue processor heating element and bimetallic thermostatic switch across a source of alternating current.

Claim 9

The invention according to claim 6 wherein said sensor comprises a mercury thermostat whose conduction state changes from a normally open circuit to a closed circuit when the temperature of the paraffin in which said mercury thermostat is partially immersed rises above said predetermined temperature.

Claim 10

The invention according to claim 6 wherein said clamp means comprises: a spring circumscribing the outer periphery of said sensor for firmly retaining said sensor; and a "U" shaped clip fastened to said spring for detachable engagement with the paraffin-containing cavity of the tissue processor to position said spring so that a portion of said spring and a portion of said sensor are immersed in the paraffin contained in the paraffin-containing cavity.

Claim 11

The invention according to claim 6 wherein said controller means comprises: a first pair of diodes coupled in series opposing fashion with the series combination of the tissue processor heating element and bimetallic switch across a source of alternating current; a second pair of diodes coupled in series opposing fashion, said second pair of diodes being coupled in parallel opposition with said first pair of diodes; a triac having a gate terminal, a first load terminal coupled to the junction between diodes of said first pair of diodes, and a second load terminal coupled to the junction between diodes of said second pair of diodes; a capacitor coupled between said first triac load terminal and said triac gate terminal; a resistor coupled between said triac gate terminal and said second triac load terminal; means for coupling said sensor across said capacitor; a printed circuit board to which said first and second pair of diodes, said triac, said capacitor and said resistor are secured; and a phenolic block encapsulating said printed circuit board.

Claim 12

The invention according to claim 6 wherein said means for detachably coupling said controller means in series with the tissue processor heating element and thermostatic switch across a source of alternating current comprises a plug tap.