An electric heater (1, 1) for heating a substance inside a tank (100), the electric heater (1, 1) comprising: at least one resistive wire (4) adapted to be connected to a source of electricity, said at least one resistive wire (4) being provided with a sheath (41) made of electrically insulating material; at least a first thermally conductive sheet (5) made of metal fixed to the at least one resistive wire (4); at least two protective layers (2, 3) made of polymer material, fixed to each other; wherein the at least one resistive wire (4) and the at least a first sheet (5) are arranged between the at least two protective layers (2, 3).

An electric heater (1, 1) for heating a substance inside a tank (100), the electric heater (1, 1) comprising: at least one resistive wire (4) adapted to be connected to a source of electricity, said at least one resistive wire (4) being provided with a sheath (41) made of electrically insulating material; at least a first thermally conductive sheet (5) made of metal fixed to the at least one resistive wire (4); at least two protective layers (2, 3) made of polymer material, fixed to each other; wherein the at least one resistive wire (4) and the at least a first sheet (5) are arranged between the at least two protective layers (2, 3).

An audio appliance includes an oscillatable diaphragm, a first heat-dissipation unit, a second heat-dissipation unit, and a control unit. The first heat-dissipation unit dissipates heat at a first rate and the second heat-dissipation unit dissipates heat at a second rate. The control unit can receive an indication of a temperature of the first heat-dissipation unit and an indication of a temperature of the second heat-dissipation unit. The control unit provides oscillation control of the oscillatable diaphragm to maintain the temperature of the first heat-dissipation unit below a first threshold and/or to maintain the temperature of the second heat-dissipation unit below a second threshold. The control unit can provide the oscillation control responsive to each of the indication of the temperature of the first heat-dissipation unit and the indication of the temperature of the second heat-dissipation unit exceeding a respective threshold.

A description is given of a process for producing a metal plate having at least one embedded heating element and of the metal plate produced by the process. The heating element is arranged between two plate bodies, and the heating element is embedded in the plate bodies by rolling with material displacement. The adjacent sides of the plate bodies have a layer of aluminum or an aluminum alloy. After a heat pre-treatment at the re-crystallization temperature of the aluminum or the aluminum alloy, the plate bodies are pressed against one another to bring about a reduction in thickness, with which the plate bodies form a diffusion bond with one another and are integrally bonded to one another over the entire surface area thereof to form the metal plate to be produced. The process produces a metal plate as a whole with better thermal conductivity and a broader spectrum of use.

A description is given of a process for producing a metal plate having at least one embedded heating element and of the metal plate produced by the process. The heating element is arranged between two plate bodies, and the heating element is embedded in the plate bodies by rolling with material displacement. The adjacent sides of the plate bodies have a layer of aluminum or an aluminum alloy. After a heat pre-treatment at the re-crystallization temperature of the aluminum or the aluminum alloy, the plate bodies are pressed against one another to bring about a reduction in thickness, with which the plate bodies form a diffusion bond with one another and are integrally bonded to one another over the entire surface area thereof to form the metal plate to be produced. The process produces a metal plate as a whole with better thermal conductivity and a broader spectrum of use.

A placement board includes: a main body unit configured to form a flow channel for circulation of a medium for heat exchange and place a workpiece thereon, the main body unit being made of a metallic material; and a heater provided in an outer edge region of the main body unit. A temperature difference between the outer edge region and an inner region of the main body unit at a surface of the main body unit where the workpiece is placed is 20? C. or more in a state where the medium has been caused to circulate through the flow channel.

A placement board includes: a main body unit configured to form a flow channel for circulation of a medium for heat exchange and place a workpiece thereon, the main body unit being made of a metallic material; and a heater provided in an outer edge region of the main body unit. A temperature difference between the outer edge region and an inner region of the main body unit at a surface of the main body unit where the workpiece is placed is 20? C. or more in a state where the medium has been caused to circulate through the flow channel.

A positive temperature coefficient (PTC) heater may include a housing and at least one PTC heating element arranged within the housing. The at least one PTC heating element may include a heating layer of a PTC material arranged between two electrode plates of the at least one PTC heating element and electrically contacted therewith. The two electrode plates may be fixed to the housing such that heat is transferable and and the two electrode plates are electrically insulated from the housing. At least one electrically insulated heat conducting layer may be arranged to divide the heating layer into a divided heating layer and may be fixed to the divided heating layer to transfer heat.

An audio appliance includes an oscillatable diaphragm, a first heat-dissipation unit, a second heat-dissipation unit, and a control unit. The first heat-dissipation unit dissipates heat at a first rate and the second heat-dissipation unit dissipates heat at a second rate. The control unit can receive an indication of a temperature of the first heat-dissipation unit and an indication of a temperature of the second heat-dissipation unit. The control unit provides oscillation control of the oscillatable diaphragm to maintain the temperature of the first heat-dissipation unit below a first threshold and/or to maintain the temperature of the second heat-dissipation unit below a second threshold. The control unit can provide the oscillation control responsive to each of the indication of the temperature of the first heat-dissipation unit and the indication of the temperature of the second heat-dissipation unit exceeding a respective threshold.

Provided is a composite heating film. The composite heating film includes conductive sheets stacked in a layered structure. Metal/metal oxide composite particles intercalated between neighboring conductive sheets among the conductive sheets are positioned. The composite heating film can generate heat with high efficiency even at a low operating voltage and can be used as a portable heating unit due to having a light weight.