1. A method for controlling resonant power converters using power transistors, particularly for induction heating systems, comprising the step of:
assessing the occurrence of non-zero voltage switching or non-zero current switching and a step of adjusting the control accordingly.
2. The method according to claim 1, wherein assessing step further includes the step of monitoring at least one electrical parameter correlated to the resonant circuit.
3. The method according to claim 1, wherein the occurrence of non-zero voltage switching or non-zero current switching is predicted from the dynamics of the induction heating system.
4. The method according to claim 2, wherein the electrical parameter is the output voltage of the resonant circuit.
5. The method according to claim 2, wherein the electrical parameter is the leg current of the power transistor of the resonant circuit.
6. The method according to claim 2, wherein the electrical parameter is the magnetic field generated by the induction heating system.
7. The method according to claim 6, wherein the magnetic field is assessed by measuring the current through a coil associated to a ferrite element of the induction heating system.
8. The method according to claim 5, wherein the waveform of at least one power transistor leg current is analyzed.
9. The method according to claim 4, wherein the coil voltage waveform is analyzed.
10. The method according to claim 2, wherein a high-pass filter circuit is applied to the output voltage Vd.
11. The method according to claim 1, wherein the step of adjusting the control comprises a real-time readapting of the dead-time delays of the power transistors.
12. The method according to claim 1, wherein the step of adjusting the control comprises a change of drive frequency in order to move away from the resonance conditions.
13. An induction heating system, particularly for cooking appliances, comprising:
a control unit with power transistors for driving induction coils,
wherein the control unit is adapted to assess the occurrence of non-zero voltage
switching or non-zero current switching and to adjust the control unit accordingly.
14. The induction heating system according to claim 13, provided with a coil magnetic shield with magnetic field concentrators, characterized in that at least one of the magnetic field concentrators is provided with a coil wire in which a current is induced by the magnetic field generated by the induction coil, the current being used as a parameter for detecting a non-zero voltage switching or non-zero current switching of the control unit.
15. The induction heating system according to claim 13, wherein the magnetic field concentrators are ferrite bars.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A personal ornament having a white coating layer comprising:
a base article of the personal ornament made of a metal, and
a white-colored stainless steel coating layer formed by a dry plating process on at least a part of the surface of the base article.
2. A personal ornament having a white coating layer comprising:
a base article of the personal ornament made of a nonferrous metal,
an underlying plating layer formed on the surface of the base article, and
a white-colored stainless steel coating layer formed by a dry plating process on at least a part of the surface of the underlying plating layer.
3. The personal ornament having a white coating layer according to claim 1 or 2, wherein a white-colored noble metal coating layer is formed in a thickness ranging from 0.04 to 0.3 m by a dry plating process on the surface of the stainless steel coating layer.
4. The personal ornament having a white coating layer according to claim 1, wherein the base article of the personal ornament is made of tungsten carbide or tantalum carbide.
5. The personal ornament having a white coating layer according to claim 2, wherein the base article of the personal ornament is made of a nonferrous metal selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, zinc, zinc alloys, magnesium, and magnesium alloys.
6. The personal ornament having a white coating layer according to claim 2, wherein the underlying plating layer has a multilayer structure constituted of at least one plating layer formed by a wet plating process and at least one plating layer formed by a dry plating process.
7. The personal ornament having a white coating layer according to claim 2 or 6, wherein the underlying plating layer comprises a coating layer which is formed by a wet plating process and is composed of at least one metal selected from the group consisting of gold, copper, nickel, chromium, tin, palladium, nickel-phosphorus alloys, nickel alloys excluding nickel-phosphorus alloys, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
8. The personal ornament having a white coating layer according to claim 7, wherein the nickel-phosphorus alloy plating layer as the underlying plating layer is a hard coating layer having been treated for age hardening.
9. The personal ornament having a white coating layer according to claim 2 or 6, wherein the underlying plating layer is a coating layer formed by a wet plating process and composed of at least one nickel-free metal selected from the group consisting of gold, copper, chromium, tin, palladium, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
10. The personal ornament having a white coating layer according to claim 2 or 6, wherein the underlying plating layer is a coating layer formed by a dry plating process and is composed of titanium carbide, zirconium carbide, or tantalum carbide.
11. The personal ornament having a white coating layer according to any of claims 2, and 6 to 10, wherein the underlying plating layer has an entire thickness ranging from 0.2 to 30 m.
12. The personal ornament having a white surface coating layer according to any of claims 1 to 3, wherein the white-colored stainless steel coating layer is composed of an austenitic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 8-22 vol % of nickel, and 15-26 vol % of chromium.
13. The personal ornament having a white coating layer according to any of claims 1 to 3, wherein the white-colored stainless steel coating layer is composed of a nickel-free ferritic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 14-20 vol % of chromium, and 0.4-2.5 vol % of molybdenum.
14. The personal ornament having a white coating layer according to any of claims 1 to 3, and 12 and 13, wherein the white-colored stainless steel coating layer is formed by a dry plating process selected from a sputtering method, an arc evaporation method, or an ion-plating method.
15. The personal ornament having a white coating layer according to any of claims 1 to 14, wherein the stainless steel coating layer has a thickness ranging from 0.1 to 2.0 m.
16. The personal ornament having a white coating layer according to any of claims 1 to 15, wherein, on the surface of the base article or of the underlying plating layer, at least one plating layer different in color tone from the white-colored stainless steel coating layer is formed by a dry plating process in addition to the stainless steel coating layer formed by a dry plating process.
17. The personal ornament having a white coating layer according to claim 16, wherein the plating layer different from the stainless steel coating layer is at least one coating layer composed of gold, gold alloys, titanium nitride, and zirconium nitride.
18. The personal ornament having a white coating layer according to claim 3, wherein the white-colored noble metal coating layer is a coating layer formed by a dry plating process and composed of a noble metal selected from the group consisting of palladium, platinum, rhodium, gold alloys, silver, and silver alloys.
19. A process for producing a personal ornament having a white coating layer comprising the steps of:
forming a base article of the personal ornament by machining a metal;
washing and degreasing the surface of the base article;
setting the base article in a dry plating apparatus selected from sputtering systems, arc evaporation systems, and ion-plating systems, and cleaning the base article by bombard cleaning in an argon gas atmosphere; and
forming a white-colored stainless steel coating layer by a dry plating process on the surface of the base article.
20. A process for producing a personal ornament having a white coating layer comprising the steps of:
forming a base article of the personal ornament from a nonferrous metal by machining;
washing and degreasing the surface of the base article;
forming on the surface of the base article an underlying plating layer by a wet plating process or a dry plating process;
setting the base article having the underlying plating layer in a dry plating apparatus selected from sputtering systems, arc evaporation systems, and ion-plating systems, and cleaning the surface of the underlying plating layer by bombard cleaning in an argon gas atmosphere; and
forming a white-colored stainless steel coating layer by a dry plating process on the surface of the underlying plating layer.
21. The process for producing a personal ornament having a white coating layer according to claim 19 or 20, which further comprises, after the formation of the white-colored stainless steel coating layer, the step of forming a white-colored noble metal coating layer in a thickness ranging from 0.04 to 0.3 m by a dry plating process on the surface of the stainless steel coating layer.
22. The process for producing a personal ornament having a white coating layer according to claim 19, wherein the metal employed for forming the base article of the personal ornament is tungsten carbide or tantalum carbide.
23. The process for producing a personal ornament having a white coating layer according to claim 20, wherein the nonferrous metal employed for forming the base article of the personal ornament is at least one nonferrous metal selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, zinc, zinc alloys, magnesium and magnesium alloys.
24. The process for producing a personal ornament having a white coating layer according to claim 20, wherein the underlying plating layer has a multilayer structure constituted of at least one plating layer formed by a wet plating process on the surface of the base article and at least one different plating layer formed thereon by a dry plating process.
25. The process for producing a personal ornament having a white coating layer according to claim 20 or 24, wherein the underlying plating layer is formed by a wet plating process from at least one metal selected from the group consisting of gold, copper, nickel, chromium, tin, palladium, nickel-phosphorus alloys, nickel alloys excluding nickel-phosphorus alloys, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
26. The process for producing a personal ornament having a white coating layer according to claim 25, wherein the nickel-phosphorus alloy plating layer as the underlying plating layer is treated for age hardening at 200 to 450 C. for 20 to 60 minutes to harden the nickel-phosphorus alloy plating layer.
27. The process for producing a personal ornament having a white coating layer according to claim 20 or 24, wherein the underlying plating layer is formed by a wet plating process from at least one nickel-free metal selected from the group consisting of gold, copper, chromium, tin, palladium, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
28. The process for producing a personal ornament having a white coating layer according to claim 20 or 24, wherein the underlying plating layer is formed from titanium carbide, zirconium carbide or tantalum carbide by a dry plating process.
29. The process for producing a personal ornament having a white coating layer according to any of claims 20, and 24 to 28, wherein the underlying plating layer has an entire thickness of ranging from 0.2 to 30 m.
30. The process for producing a personal ornament having a white coating layer according to any of claims 19 to 21, wherein the white-colored stainless steel coating layer is composed of an austenitic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 8-22 vol % of nickel and 15-26 vol % of chromium; and is formed by a sputtering method, an arc evaporation method or an ion plating method.
31. The process for producing a personal ornament having a white coating layer according to any of claims 19 to 21, wherein the white-colored stainless steel coating layer is composed of a nickel-free ferritic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1 -1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 14-20 vol % of chromium, and 0.4-2.5 vol % of molybdenum; and is formed by a sputtering method, an arc evaporation method, or an ion plating method.
32. The process for producing a personal ornament having a white coating layer according to any of claims 19, 20, and 22 to 31, which further comprises,
after the steps of forming a white-colored stainless steel coating layer on the surface of the ornament base article or of the underlying coating layer,
at least once the steps of:
masking a part of the stainless steel coating layer,
forming a plating layer different in color tone from the stainless steel coating layer on the surface of the stainless steel coating layer and the surface of the mask by a dry plating process, and
removing the mask and the coating layer on the mask,
to thereby provide an outermost plating layer having a white-colored stainless steel coating layer portion and at least one plating layer portion different in color tone from the stainless steel coating layer.
33. The process for producing a personal ornament having a white coating layer according to claim 32, wherein the plating layer different in color tone from the stainless steel coating layer is at least one coating layer formed from a metal selected from the group consisting of gold, gold alloys, titanium nitride, hafnium nitride and zirconium nitride by a dry plating process selected from sputtering methods, arc evaporation methods, and ion plating methods.
34. The process for producing a personal ornament having a white coating layer according to claim 21, wherein the white-colored noble metal coating layer is a coating layer formed by a dry plating process from a noble metal selected from the group consisting of palladium, platinum, rhodium, gold alloys, silver and silver alloys.