High-frequency power supply device

Abstract

Provided is a high-frequency power supply device capable of suppressing excessive current from flowing through a transformer and causing appropriate current to flow through the transformer. The high-frequency power supply device is of a self-oscillation type and includes a DC power supply (1), an LC resonant circuit (5), a switching circuit (3), and a transformer (6). The LC resonant circuit includes a capacitor (52) and an induction coil (51) for generating plasma. The switching circuit includes a semiconductor element (31) that switches DC power supplied from the DC power supply to supply the DC power to the LC resonant circuit. The transformer has a primary coil (53) included in the LC resonant circuit and a secondary coil (33) connected to the semiconductor element to turn the semiconductor element on / off. The transformer is formed in a coaxial structure in which the primary coil and the secondary coil are coaxially arranged, and the LC resonant circuit has a resistor (54) connected in parallel to the primary coil.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-frequency power supply device of a self-oscillation type. BACKGROUND

[0002] One example of a conventional high-frequency power supply of a self-oscillation type is disclosed in Patent Literature 1. In the transformer of the high-frequency power supply device disclosed in Patent Literature 1, the primary coil and the secondary coil are formed in a manner such that they are coaxial. Further, a semiconductor of the high-frequency power supply device is driven by a voltage applied via the transformer.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2016-51556 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the above-described high-frequency power supply device, it is difficult to adjust the turns ratio of the primary coil and the secondary coil on the structure of the transformer, and therefore it is preferable to additionally provide a structure for appropriately setting the current flowing through the transformer.

[0008] The present application has been achieved in view of the above-described actual circumstances, and aims to provide a high-frequency power supply device capable of suppressing excessive current from flowing through a transformer and causing appropriate current to flow through the transformer.

[0009] SOLUTION TO PROBLEM

[0010] A first aspect of the present application is a high-frequency power supply device of a self-oscillation type that includes a direct-current power supply, an LC resonance circuit, a switching circuit, and a transformer. The LC resonance circuit includes a capacitor and an inductor for generating plasma. The switching circuit includes a semiconductor element that switches direct-current power supplied from the direct-current power supply to supply the direct-current power to the LC resonance circuit. The transformer has a primary coil included in the LC resonance circuit, and a secondary coil connected to the semiconductor element to turn the semiconductor element on / off. The transformer is formed in a coaxial structure in which the primary coil and the secondary coil are coaxially arranged, and the LC resonance circuit has a resistor connected in parallel to the primary coil.

[0011] EFFECT OF THE INVENTION

[0012] According to the first aspect of the present application, the resistor is connected in parallel to the primary coil of the transformer, and therefore it is possible to suppress excessive current from flowing through the transformer and to cause appropriate current to flow through the transformer. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a circuit diagram showing a structure example of the high-frequency power supply device of the present embodiment.

[0014] Figure 2 is a schematic diagram for explaining the internal structure of the transformer of the present embodiment.

[0015] Figure 3 is an example of a partial plan view showing a structure example of the periphery of the MOSFET of the present embodiment.

[0016] Figure 4 is a cross-sectional view showing the A-A cross section of Figure 3

[0017] Figure 5 is a cross-sectional view showing the B-B cross section of Figure 3

[0018] Figure 6 is another example of a partial plan view showing a structure example of the periphery of the MOSFET of the present embodiment.

[0019] Figure 7 is an example of a circuit diagram showing a structure example of the LC resonant circuit.

[0020] Figure 8 is still another example of a partial plan view showing a structure example of the periphery of the MOSFET of the present embodiment.

[0021] Figure 9 is a schematic cross-sectional view showing the overall structure of the high-frequency power supply device of Figure 1 DETAILED DESCRIPTION

[0022] 1. Electrical structure of high-frequency power supply device

[0023] Figure 1 is a circuit diagram showing a structure example of the high-frequency power supply device of the present embodiment. The high-frequency power supply device can be applied, for example, to an analysis device such as an inductively coupled plasma (ICP) emission analysis device, and is a high-frequency power supply device of a self-excited oscillation type provided with a direct-current power supply 1, a bypass capacitor 2, a switching circuit 3, an impedance conversion circuit 4, and an LC resonant circuit 5, and the like.

[0024] The direct-current power supply 1 sets the direct-current voltage of the switching circuit 3 and determines the high-frequency electric power supplied to the LC resonant circuit 5. The bypass capacitor 2 is disposed between the direct-current power supply 1 and the switching circuit 3, and ensures a low-impedance high-frequency current path.

[0025] ​​​The LC resonance circuit 5 includes an induction coil 51 and a capacitor 52 connected to the induction coil 51. The induction coil 51 included in the LC resonance circuit 5 is used to generate plasma by supplying high-frequency electric power from the direct-current power supply 1 to the induction coil 51 via the switching circuit 3, and plasma can be generated in a plasma torch (not shown).

[0026] The impedance conversion circuit 4 includes two coils 41, 42 and a capacitor 43 connected in series between the coils 41, 42. A loop including the coils 41, 42 and the capacitor 43 of the impedance conversion circuit 4 is formed between the switching circuit 3 and the impedance conversion circuit 4. In addition, a loop including the capacitor 43 of the impedance conversion circuit 4, and the induction coil 51 and the capacitor 52 of the LC resonance circuit 5 is formed between the impedance conversion circuit 4 and the LC resonance circuit 5.

[0027] The switching circuit 3 is a structure including semiconductor elements, and is connected to the direct-current power supply 1 via the semiconductor elements. In this example, the switching circuit 3 is configured by a bridge circuit including four MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors) 31 (31a, 31b, 31c, 31d). The switching circuit 3 is configured by a half-bridge type or a full-bridge type bridge circuit. However, the semiconductor elements included in the switching circuit 3 are not limited to MOSFETs. In addition, the switching circuit 3 is not limited to a half-bridge type or a full-bridge type.

[0028] The direct-current power supply 1 and the bypass capacitor 2 are connected between the drain electrode of the MOSFET 31a and the source electrode of the MOSFET 31b. In addition, the source electrode of the MOSFET 31a and the drain electrode of the MOSFET 31b are connected by a wiring 35, and the coil 41 of the impedance conversion circuit 4 is connected to a middle portion of the wiring 35.

[0029] The direct-current power supply 1 and the bypass capacitor 2 are connected between the drain electrode of the MOSFET 31c and the source electrode of the MOSFET 31d. In addition, the source electrode of the MOSFET 31c and the drain electrode of the MOSFET 31d are connected by a wiring 36, and the coil 42 of the impedance conversion circuit 4 is connected to a middle portion of the wiring 36.

[0030] The gate electrodes of the MOSFETs 31a, 31b, 31c, 31d are connected to gate drive circuits 32 (32a, 32b, 32c, 32d). Thus, the MOSFETs 31 are switched to an on state or an off state at a predetermined timing by the gate drive circuits 32. As a result, the direct-current electric power supplied from the direct-current power supply 1 is switched to supply the direct-current electric power to the LC resonance circuit 5.

[0031] Each of the gate drive circuits 32a, 32b, 32c, 32d has a coil 33 (33a, 33b, 33c, 33d) and a capacitor 34 (34a, 34b, 34c, 34d) connected in parallel to each other. The coil 33 included in the gate drive circuit 32 constitutes a secondary coil of each transformer, and the coil 33 is connected to the control terminal (gate electrode, source electrode) of the MOSFET 31 to turn on / off (switch) the MOSFET 31. A primary coil of each transformer is constituted by the coil 53 (53a, 53b, 53c, 53d) included in the LC resonant circuit 5.

[0032] Thus, in the present embodiment, the transformer constituted by the pair of the coil 53 and the coil 33 is provided in association with each of the MOSFETs 31, so that the feedback voltage can be supplied to each of the MOSFETs 31.

[0033] In addition, in the present embodiment, the transformer is constituted by the coil (primary coil) 53 and the coil (secondary coil) 33, so that when excessive current flows in the primary coil 53, excessive current also flows in the secondary coil 33, and thus it is likely that the MOSFET 31 is adversely affected.

[0034] In the present embodiment, as a structure for appropriately setting the current flowing through the transformer, the resistor 54 (54a, 54b, 54c, 54d) is connected in parallel to each of the transformers, specifically, to each of the primary coils 53a, 53b, 53c, 53d. In addition, the coil 53 and the resistor 54 connected in parallel are connected in series to the induction coil 51 and the capacitor 52.

[0035] The resistor 54 is an electrically conductive body having a resistance value. That is, the resistor 54 can also be referred to as a current flow path having a resistance value. As the resistor 54, for example, a metal plate and a resistance element, and the like are cited.

[0036] Thus, by connecting the primary coil 53 of the transformer in parallel to the resistor 54, it is possible to suppress the flow of excessive current through the transformer, and to cause appropriate current to flow through the transformer.

[0037] 2. Internal structure of transformer

[0038] Figure 2 is a schematic diagram for explaining the internal structure of the transformer 6 of the present embodiment. The transformer 6 is constituted by the primary coil 53 included in the LC resonant circuit 5 and the secondary coil 33 included in the gate drive circuit 32.

[0039] In the present embodiment, the transformer 6 is constituted by a semi-rigid coaxial cable. The semi-rigid coaxial cable is coaxially provided with a wire-shaped center conductor 61, a cylindrical insulator 62 covering the outside of the center conductor 61, and a cylindrical outer conductor 63 covering the outside of the insulator 62. The primary coil 53 of the transformer 6 is constituted by the outer conductor 63, and the secondary coil 33 is constituted by the center conductor 61.

[0040] Thus, the transformer 6 becomes a coaxial structure in which the primary coil 53 and the secondary coil 33 are coaxially provided, and even in a case where the transformer 6 is bent or folded, the state in which the primary coil 53 and the secondary coil 33 are arranged in parallel with each other is maintained. However, it can also be that the primary coil 53 of the transformer 6 is constituted by the center conductor 61, and the secondary coil 33 is constituted by the outer conductor 63.

[0041] 3. Structure of the periphery of the MOSFET

[0042] Figure 3 is an example of a partial plan view showing a structure example of the periphery of the MOSFET 31 of the present embodiment. Also, Figure 4 is a cross-sectional view showing the A-A cross section of Figure 3 . Also, Figure 5 is a cross-sectional view showing the B-B cross section of Figure 3 .

[0043] Also, in Figures 3 to 5 , only the structure of the periphery of one of the MOSFETs 31, such as the MOSFET 31a, is shown, but the same structure can be adopted for the structure of the periphery of each of the MOSFETs 31.

[0044] In the present embodiment, each of the circuits such as the switching circuit 3, the impedance conversion circuit 4, and the LC resonance circuit 5 is mounted to the substrate 10. The components included in each of the circuits are electrically connected to each other by the pattern wiring 11 and the pattern wiring 12. The current flowing in the induction coil 51 for generating plasma is very large, and thus, when the width of the pattern wiring 11 is small, the heat generation becomes excessive, which is not allowed. Therefore, as the pattern wiring 11, a pattern having a large width is preferably used. Further, the substrate 10 can be one sheet, or can be divided into two or more sheets.

[0045] Each transformer 6 is formed in a U-shape. A U-shape refers to a shape where the two ends 60a and 60b of the transformer 6 are bent or folded close to each other; it also includes other shapes that are essentially U-shaped, such as a semi-circle. The transformer 6, constructed from semi-rigid coaxial cables, does not have a protective sheath on the outside of the outer conductor 63, leaving the outer conductor 63 exposed. The primary coil 53 of each transformer 6 is connected to the pattern wiring 11. On the side of the substrate 10 opposite to the pattern wiring 11 side, the input (IN) and output (OUT) terminals of the secondary coil 33 of the transformer 6 are electrically connected to the control terminals (gate electrode 301, source electrode 302) of the MOSFET 31 using the pattern wiring 12.

[0046] Furthermore, in this embodiment, by forming the transformer 6 in a U-shape, it is ensured that only a sufficient length of feedback voltage can be generated, and the pattern wiring 12 between the input (IN) and output (OUT) terminals of the secondary coil 33 of the transformer 6 and the control terminals (gate electrode 301, source electrode 302) of the MOSFET 31 is shortened, thereby suppressing the attenuation of the feedback voltage caused by the pattern inductance. Additionally, by arranging the primary coil 53 and the secondary coil 33 of the transformer 6 in parallel, the coupling between the primary coil 53 and the secondary coil 33 is increased.

[0047] Through these structural designs, sufficient feedback voltage can be supplied to MOSFET 31 via transformer 6. In other words, sufficient current can be supplied to each MOSFET 31 via transformer 6.

[0048] This increases the feedback voltage, so in this embodiment, it is not necessary to supply a DC bias voltage to the control terminal of each MOSFET 31. That is, when the semiconductor element of the switching circuit 3 is composed of MOSFET 31 as in this embodiment, the amplitude of the gate voltage of each MOSFET 31 can be increased, thereby eliminating the need to supply a DC bias voltage to the gate electrode of each MOSFET 31.

[0049] And, as Figure 1 As shown, by connecting capacitor 34 in parallel with secondary coil 33 to the control terminals of each MOSFET 31, the effects of deviations and variations in the gate-source capacitance of each MOSFET 31 can be reduced. Furthermore, the voltage at the control terminals of each MOSFET 31, which has nonlinear gate charging characteristics, changes more linearly, thus suppressing ringing of the switching waveform caused by the inductance of the load and achieving high power efficiency.

[0050] In addition, in this embodiment, such as Figure 3 and Figure 5As shown, each resistor 54 is connected to the pattern wiring 11. The transformer 6 is formed as a coaxial structure with the primary coil 53 and the secondary coil 33 arranged coaxially. Therefore, it is difficult to adjust the magnitude of the current in the primary coil 53 and the secondary coil 33 by adjusting the turns ratio. However, for example, the magnitude of the current in the primary coil 53 and the secondary coil 33 can be easily adjusted simply by replacing the resistor 54 with other resistors 54 with different resistance values.

[0051] Furthermore, even if resistor 54 is made of the same conductive material, its resistance value will differ depending on the length of the current flow path. Specifically, although the conductive materials are the same, the resistance value of a conductive material with a longer current flow path is greater. Therefore, among conductive materials of a given type, the longer the current path of resistor 54, the greater its resistance value.

[0052] If the resistor 54 is formed in the same U-shape as the transformer 6 as in this embodiment, sufficient resistance value can be ensured even if, for example, the connection position of the end 540a of the resistor 54 is close to the connection position of 540b.

[0053] Furthermore, even if resistor 54 is made of the same conductive material, its resistance value will differ depending on the cross-sectional area of ​​the current flow path. Specifically, although the conductive materials are the same, the conductor with a smaller cross-sectional area of ​​the current flow path has a larger resistance value. Therefore, among conductive materials of a given type, the smaller the cross-sectional area of ​​the current path of resistor 54, the larger its resistance value.

[0054] Therefore, the resistance value of resistor 54 is determined by its material and shape. Furthermore, in this embodiment, when the resistance value of resistor 54 is extremely small compared to the parasitic resistance of the primary coil 53, the magnitude of the current flowing through resistor 54 increases. That is, the current flowing through the primary coil 53 becomes extremely small. In this case, the voltage (current) required to drive MOSFET 31 may not be supplied to MOSFET 31.

[0055] In this embodiment, such as Figures 3 to 5 As shown, resistor 54 is formed in the same U-shape as transformer 6, but the material and shape of resistor 54 are not particularly limited as long as it is supplied with a voltage above the minimum voltage required to drive MOSFET 31.

[0056] In addition, such as Figures 3 to 5 As shown, in this embodiment, the transformer 6 and the resistor 54 extend towards each other and in parallel. The insulating heat sink 20 is located between the transformer 6 and the resistor 54 and is in contact with the transformer 6 and the resistor 54.

[0057] That is, the transformers 6 and the resistors 54 are bent or folded in planes F1, F2 parallel to each other, which are in contact with the heat sink 20.

[0058] 4. Modification of the heat sink and LC resonance circuit

[0059] Each of the heat sinks 20 on the substrate 10 can be in contact with each of the pairs of the transformers 6 and the resistors 54 as shown in FIG. 6A, or one heat sink 20 can be in contact with each of the pairs of the transformers 6 and the resistors 54 as shown in FIG. 6B. Further, the heat sink 20 can be in contact with each of the pairs of the transformers 6 and the resistors 54 as shown in FIG. 6C. Figures 3 to 5 Figure 6 Further, the heat sink 20 can be in contact with each of the pairs of the transformers 6 and the resistors 54 as shown in FIG. 6C. Figure 6 is another example of a partial plan view showing a structure example of the periphery of the MOSFET 31 of the present embodiment. Also, in Figure 6 , specifically, the structure of the periphery of two MOSFETs 31 in the MOSFETs 31a and the like is shown.

[0060] Further, as shown in the LC resonance circuit 5 shown in FIG. 5, the resistor 54 can be connected in parallel to a plurality of the primary coils 53. For example, as shown in FIG. 6D, in a case where the resistor 54 is connected in parallel to two primary coils 53, the periphery of the MOSFET 31 can be configured as shown in FIG. 6E. Further, Figure 7 Figure 7 Further, the heat sink 20 can be in contact with each of the pairs of the transformers 6 and the resistors 54 as shown in FIG. 6C. Figure 8 Figure 7 is an example of a circuit diagram showing a structure example of the LC resonance circuit 5. Also, Figure 8 is still another example of a partial plan view showing a structure example of the periphery of the MOSFET 31 of the present embodiment. Also, in Figure 8 , specifically, the structure of the periphery of two MOSFETs 31 in the MOSFETs 31a and the like is shown.

[0061] Thus, in the present embodiment, as long as the heat sink 20 is provided on the substrate 10, each of the transformers 6 and each of the resistors 54 can be cooled by at least one heat sink 20.

[0062] The heat sink 20 is constituted by, for example, a block of aluminum nitride. However, as long as the material has a high thermal conductivity and insulating properties, the heat sink 20 can be formed of a material other than aluminum nitride.

[0063] ​​​In the present embodiment, the transformer 6 is constituted by a coaxial cable, and thus the outer surface of the transformer 6 is a circumferential surface. Thus, in the case where the contact surface of the heat sink 20 that contacts the transformer 6 is constituted by a flat surface, the heat sink 20 can not be sufficiently cooled because it contacts only a small portion of the coaxial cable. Therefore, it is preferable to coat, for example, a heat-conductive grease on the periphery of the portion of the transformer 6 that contacts the heat sink 20, or to provide the contact surface of the heat sink 20 that contacts the transformer 6 as a concave surface that corresponds to the outer surface of the transformer 6, thereby increasing the contact area of the heat sink 20 with the transformer 6. The same can be said of the resistor 54.

[0064] 5. Overall structure of high-frequency power supply device

[0065] Figure 9 is a schematic cross-sectional view showing an overall structure of a high-frequency power supply device. Figure 1 The high-frequency power supply device has a structure in which various components are provided inside a hollow housing 100. A through-hole or the like for inserting a cable is formed in the housing 100, but no opening is formed other than this, and the inside of the housing 100 is in a substantially airtight state. That is, no air intake port for sucking air into the housing 100, or an air exhaust port for exhausting air from the housing 100, or the like is formed in the housing 100.

[0066] The space inside the housing 100 is divided by one or more division walls 101. A substrate 10 on which various circuits such as the switching circuit 3, the impedance conversion circuit 4, and the LC resonant circuit 5 are mounted is held by the division wall 101, for example. Thus, various components such as the switching circuit 3, the LC resonant circuit 5, and the transformer 6 are housed inside the housing 100.

[0067] However, the induction coil 51 included in the LC resonant circuit 5 is not housed inside the housing 100, but is disposed inside a plasma stand (not shown). The substrate 10 inside the housing 100 and the induction coil 51 outside the housing 100 are connected by a conductor such as a copper plate, and the induction coil 51 and the plasma stand are separated by an insulator such as a fluororesin.

[0068] The heat sink 23 provided inside the housing 100 is mounted to the substrate 10. The heat sink 23 is, for example, a water-cooling type, and has a main body 21 through which a refrigerant flows, and a plurality of fins 22 that protrude from the main body 21. The heat sink 23 mainly cools the MOSFET 31 mounted to the substrate 10. It is also possible to bring the main body 21 into direct contact with the substrate 10, for example, to cool the substrate 10 and components mounted to the substrate 10. However, since the heat is dissipated through the insulating material of the substrate 10, the heat dissipation is insufficient.

[0069] Therefore, in the housing 100, in addition to the substrate 10 and the heat sink 23 described above, an air cooling fan 40 is provided. The air cooling fan 40 is held by the partition wall 101, for example, facing the surface of the substrate 10 on the side opposite to the side of the heat sink 23. Thus, in a case where the air cooling fan 40 is rotationally driven, the air in the housing 100 is blown from the air cooling fan 40 toward the substrate 10.

[0070] The space in the housing 100 partitioned by the partition wall 101 constitutes a circulation path 102 for circulating the air in the housing 100. That is, the air blown from the blowout port 401 of the air cooling fan 40 is sucked into the air cooling fan 40 after being directly blown against the substrate 10 and the heat sink 23 provided midway in the circulation path 102, and is blown out again from the blowout port 401.

[0071] The plurality of fins 22 provided in the heat sink 23 are arranged in parallel at intervals from each other in a manner so as to extend along the flow direction of the air in the circulation path 102. In this way, the heat sink 23 (fins 22) is arranged midway in the circulation path 102, whereby the air in the housing 100 can be circulated while being guided toward the heat sink 23 by the air cooling fan 40.

[0072] In this way, in the present embodiment, the components such as the LC resonant circuit 5 excluding the induction coil 51, the switching circuit 3, and the transformer 6 are housed in the housing 100, and the air in the housing 100 is circulated by the air cooling fan 40, whereby the air outside the device is difficult to flow into the device. Thus, it is possible to prevent the components in the device from being contaminated by the air outside the device.

[0073] In addition, the components in the housing 100 are cooled by the water-cooling type heat sink 23, and the air circulated in the housing 100 by the air cooling fan 40 is circulated while being cooled by the water-cooling type heat sink 23, whereby a high cooling efficiency can be achieved. Thus, even in a structure in which the air outside the device is difficult to flow into the device, the components in the device can be cooled well.

[0074] 6. Other modifications

[0075] In the above embodiment, a case where the LC resonant circuit 5 having the induction coil 51 is constituted by a series resonant circuit in which the capacitor 52 and the induction coil 51 are connected in series is described. However, the LC resonant circuit 5 can be constituted by a parallel resonant circuit in which the capacitor 52 and the induction coil 51 are connected in parallel, not limited to such a structure.

[0076] The transformer 6 is not limited to one made of a semi-rigid coaxial cable, and can be made of another coaxial cable. In a case where a coaxial cable provided with a protective cover is used as the transformer 6, it is preferable to use it after removing the protective cover. However, the structure is not limited to one using a coaxial cable, and can be one in which only the primary coil 53 of the transformer 6 is arranged coaxially with the secondary coil 33.

[0077] In addition, as the resistor 54, a component provided in the high-frequency power supply device can be used, and specifically, a component that can be electrically connected, that is, a component having conductivity and a resistance value can be used.

[0078] For example, in a case where the high-frequency power supply device is provided with a fan of a general metal housing, and the fan of the general metal housing is used as the resistor 54, if it is arranged such that the heat sink 20 is directly blown by air blown from the fan, the cooling efficiency of the heat sink 20 can be improved.

[0079] In addition, in a plurality of substrates 10, even if various circuits are identically configured, depending on differences in quality and the like of components, the value of current flowing through the transformer 6 sometimes slightly differs. If a variable resistor is used as the resistor 54, even if the current flowing through the transformer 6 is a current different from the original value, the current flowing through the transformer 6 can be appropriately adjusted without replacing the resistor 54. That is, it is easy to maintain a certain quality in the manufacture of the high-frequency power supply device.

[0080] The high-frequency power supply device according to the present application is not limited to an ICP emission analysis device, and can be applied to other analysis devices that perform analysis using plasma. In addition, the high-frequency power supply device according to the present application is not limited to an analysis device, and can be applied to other various devices that use plasma (for example, a high-frequency oscillation circuit for plasma CVD, and the like).

[0081] 7. Mode

[0082] The person skilled in the art will understand that the above-described embodiments are specific examples of the following modes.

[0083] (First item) In a self-oscillation mode high-frequency power supply device according to one mode, it can be provided with:

[0084] a direct-current power supply;

[0085] an LC resonance circuit including a capacitor and an induction coil for generating plasma;

[0086] a switching circuit including a semiconductor element that switches direct-current power supplied from the direct-current power supply to supply direct-current power to the LC resonance circuit; and

[0087] A transformer having a primary coil included in the LC resonance circuit, and a secondary coil connected to the semiconductor element to make the semiconductor element conductive / non-conductive,

[0088] wherein the transformer is formed in a coaxial structure in which the primary coil and the secondary coil are coaxially arranged,

[0089] The LC resonance circuit has a resistor connected in parallel to the primary coil.

[0090] According to the high-frequency power supply device of the self-oscillation type according to the first aspect, by connecting the resistor in parallel to the primary coil of the transformer, excessive current can be suppressed from flowing through the transformer, and appropriate current can be made to flow through the transformer.

[0091] (Second aspect) In the high-frequency power supply device of the self-oscillation type according to the first aspect, it can also be that,

[0092] The transformer and the resistor are in a U shape.

[0093] According to the high-frequency power supply device of the self-oscillation type according to the second aspect, a length that can only generate sufficient feedback voltage can be ensured, and the wiring between the input end and the output end of the secondary coil of the transformer and the semiconductor element can be shortened, thereby suppressing the attenuation of the feedback voltage caused by pattern inductance. In addition, even if the connection positions of the ends of the resistor are close, sufficient resistance value can be ensured.

[0094] (Third aspect) In the high-frequency power supply device of the self-oscillation type according to the first aspect or the second aspect, it can also be that,

[0095] a heat sink having insulation is further provided,

[0096] The heat sink is in contact with both the transformer and the resistor.

[0097] According to the high-frequency power supply device of the self-oscillation type according to the third aspect, heat from the transformer and the resistor is dissipated via the heat sink, so high heat dissipation efficiency can be achieved.

[0098] (Fourth aspect) In the high-frequency power supply device of the self-oscillation type according to the third aspect, it can also be that,

[0099] The transformer and the resistor extend toward each other and in parallel,

[0100] The heat sink is located between the transformer and the resistor.

[0101] According to the high-frequency power supply device of the self-oscillation type according to the fourth aspect, the transformer and the resistor can be cooled using at least one heat sink.

[0102] (Fifth) In any one of the first to fourth aspects, the self-oscillation type high-frequency power supply device can also be,

[0103] The resistor is a variable resistor.

[0104] According to the self-oscillation type high-frequency power supply device according to the fifth aspect, the current flowing through the transformer can be adjusted without replacing the resistor.

Claims

1. A high-frequency power supply device with a self-excited oscillation mode, comprising: DC power supply; An LC resonant circuit includes a capacitor and an induction coil for generating plasma; A switching circuit includes a semiconductor element that switches on and off DC power supplied from the DC power source to provide DC power to the LC resonant circuit; and A transformer having a primary coil included in the LC resonant circuit and a secondary coil connected to the semiconductor element to turn the semiconductor element on / off. in, The transformer is configured as a coaxial structure with the primary coil and the secondary coil arranged coaxially. The LC resonant circuit includes a plurality of primary coils forming a loop circuit together with the induction coil and the capacitor, and has a plurality of resistors connected in parallel with the plurality of primary coils respectively.

2. The high-frequency power supply device with self-excited oscillation mode according to claim 1, characterized in that, The transformer and the resistor are U-shaped.

3. The high-frequency power supply device with self-excited oscillation mode according to claim 1, characterized in that, It also features an insulated radiator. The heat sink is in contact with both the transformer and the resistor.

4. The high-frequency power supply device with self-excited oscillation mode according to claim 3, characterized in that, The transformer and the resistor extend towards each other and parallel to each other. The heat sink is located between the transformer and the resistor.

5. The high-frequency power supply device with self-excited oscillation mode according to any one of claims 1 to 4, characterized in that, The resistor is a variable resistor.

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