Abstract
The invention relates to an electrode arrangement for a plasma jet device comprising a first and a second printed circuit board each having an exposed surface of a circuit path serving as electrode and facing the other printed circuit board, a spacer arranged between the first and second circuit board and a plasma cell arranged between the first and second printed circuit board and the spacer wherein the plasma cell has a gas inlet and a plasma outlet. The invention further relates to a plasma head comprising said electrode arrangement.
Claims
1. An electrode arrangement for a plasma jet device comprising: a) a first and a second printed circuit board each having an exposed surface of a circuit path serving as electrode b) a spacer arranged between the first and second circuit board c) a plasma cell arranged between the first and second printed circuit board and the spacer wherein the plasma cell has a gas inlet and a outlet, the exposed surface of a circuit path is facing the other printed circuit board.
2. The electrode arrangement according to claim 1 wherein the spacer is made of plastic, preferably polyimide.
3. The electrode arrangement according to claim 1, wherein the electrode is laterally spaced apart from the spacer, preferably wherein a groove is arranged in the printed circuit board between the electrode and the spacer, further preferably wherein the groove has a depth being equal or greater than the thickness of the circuit path layer.
4. The electrode arrangement according to claim 1, wherein the first and second printed circuit board are arranged in parallel to each other.
5. The electrode arrangement according to claim 1, wherein the first and the second printed circuit board have an identical shape and are arranged in a flipped position.
6. The electrode arrangement according to claim 1, wherein the printed circuit board has a finger-shaped projection at a rear end having an electrical connection.
7. The electrode arrangement according to claim 1, wherein the exposed surfaces of the circuit path comprise a coating, preferably a gold coating.
8. The electrode arrangement according to claim 1, wherein the first and second printed circuit boards and the spacer are made of a flexible material.
9. The electrode arrangement according to claim 1, wherein the first and the second electrode are adapted to be connected with a pulsed voltage source such that pulse discharges between the first and the second electrode may be generated.
10. A plasma head having a first end and an opposite second end comprising: (a) an electrode arrangement according to claim 1 on the first end; (b) a connector for connecting the plasma head with a handle on the second end; and (c) electrical and gas connections from the connector to the electrode arrangement.
11. The plasma head according to claim 9 having a plasma exiting tip in form of a hollow cylinder, preferably made of polyimide.
12. The plasma head according to claim 9 having a plasma exiting tip consisting of two sheets which are connected to each other at the two lateral sides, preferably wherein the sheets are a polyimide film, preferably wherein the electrode arrangement is part of the plasma exiting tip
13. The plasma head according to claim 10, wherein the connector comprises a mechanical connector having cylindrical segments arranged coaxially to each other and two electrical connectors extending radially beyond the outer cylindrical surface of the cylindrical segments.
14. The plasma head according to claim 13, wherein each of the electrical connectors is connected to a printed circuit board, wherein the two printed circuit boards are connected to build a support extending along the axis of the cylindrical segments.
15. The plasma head according to claim 14, wherein a gas connector at a front face of the cylindrical segments a-e is fluidly connected with a hollow of the support.
Description
[0026] Preferred embodiments of the present invention are described by the way of example only, with reference to the accompanying drawings in which
[0027] FIG. 1 shows a first view of an electrode arrangement;
[0028] FIG. 2 shows a second view of the electrode arrangement;
[0029] FIG. 3 shows a 3-dimensional view of a plasma head in a first embodiment comprising an electrode arrangement;
[0030] FIG. 4 shows a sectional view of the plasma head according to FIG. 3;
[0031] FIG. 5 shows a 3-dimensional view of a plasma head in a second embodiment comprising an electrode arrangement in a plasma exiting tip
[0032] FIG. 6 shows a 3-dimensional view of a plasma head in a third embodiment comprising an electrode arrangement in a plasma exiting tip
[0033] FIG. 7a-e show partial views of five embodiments of a plasma exiting tip
[0034] FIGS. 1 and 2 show an electrode arrangement 10 for a plasma jet device. The electrode arrangement 10 comprises a first printed circuit board 20 and a second printed circuit board 30 which are arranged parallel to and on top of each other. Each of the two printed circuit boards 20, 30 has a conductive track 22, 32 attached to a substrate 21, 31. The printed circuit boards 20, 30 of the present embodiment are each a one-layer substrate having conductive tracks 22, 32 that are only on one side of the substrate 21, 31. The substrate 21, 31 is made of an isolating material. In the present embodiment, the substrate 21, 31 is made of FR4 or any common PCB material and the conductive tracks 22, 32 are made of copper. In alternative embodiments the printed circuit board 20, 30 may be multi layered and/or comprising two-sided circuit boards.
[0035] Each of the printed circuit boards 20, 30 has a finger-shaped projection 26, 36 with an electric connection 27, 37. The electrical connections 27, 37 may be connected with an electrical wiring (not shown) of the electrode arrangement 10. The two printed circuit boards 20, 30 are spaced apart from each other and kept in this position by the way of a spacer 12. A plasma cell 11 is located between the two printed circuit boards 20, 30 and the spacer 12.
[0036] FIG. 2 shows an electrode arrangement 10 in which, only for the sake of demonstrating the structure of the elements between the two substrates, the second printed circuit board 30 is tilted upwards. In general, the two printed circuit boards 20, 30 are arranged parallel to each other, wherein especially the exposed surfaces of the conductive tracks are in parallel to each other 23, 33. The electrode arrangement 10 shown in FIG. 2 may be the same as the electrode arrangement 10 shown in FIG. 1. As can be seen, the two printed circuit boards 20, 30 have an identical shape and structure. The second printed circuit board 30 is flipped, i.e. is arranged in a flipped position, with regard to the first printed circuit board 20, such that the conductive tracks 22, 32 are facing each other. The conductive tracks 22, 32 are largely covering one surface of the substrate 21, 31. The plasma cell 11 has a gas inlet 13 and a plasma outlet 14. The conductive tracks 22, 32 have an exposed surface 23, 33 inside the plasma cell 11, such that the gas entering the plasma cell 11 through the inlet 13 gets ignited in the plasma cell 11 and subsequently exits the electrode arrangement 10 through the outlet 14. The outlet 14 extends in between the printed circuit boards 20, 30 and the spacer 12. The conductive tracks 22, 32 are covered on the inside of the plasma cell 11 by a gold coating 24, 34 (not shown) in order to have a better chemical and physical resistance against the plasma. In the plasma cell 11 prevails in normal operation a flow direction from the inlet 13 to the outlet 14. Inside the plasma cell 11 is a groove 25, 35 in the surface of the printed circuit boards 20, 30 on both sides of the plasma cell 11 along the spacer 12. The grooves 25, 35 have in one embodiment a depth of the thickness of the conductive track 22, 32 such that the conductive track 22, 32 is interrupted between the exposed surface 23, 33 and the conductive track 22, 32 below the spacer 12. The groove 25, 35 as shown in the embodiment is not machined into the substrate 21, 31. In another embodiment, the groove 25, 35 may reach into the substrate 21, 31.
[0037] The spacer 12 is shown in FIG. 2 attached to the first printed circuit board 20, particularly to the conductive track 22 of the first printed circuit board 20. In the assembled state, as shown for example in FIG. 1, the spacer is attached to both printed circuit boards 20, 30, especially to both conductive tracks 22, 32. The spacer 12 comprises in one embodiment two spacer parts wherein each spacer part provides a side wall of the plasma cell 11. Both parts are arranged besides the plasma cell and extend along plasma cell 11 in flow direction. These both spacer parts are basically separated by the plasma cell 11 with the inlet 13 and the outlet 14. The spacer 12 defines the distance between the two exposed surfaces 23, 33 serving as electrodes for igniting the plasma. In alternative embodiments, the spacer 12 and the spacer parts may have a similar or the same shape but may consist of two layers wherein each layer is attached to one of the printed circuit boards 20, 30.
[0038] Due to the flipped arrangement of the two printed circuit boards, both finger shaped projections 26, 36 are arranged on the same end, i.e. on the end at which the gas inlet 13 is allocated, but on the opposite side. The two electrical connections 27, 37 are easily accessible such that the wiring of the electrode arrangement 10 may be attached thereto, e. g. by soldering.
[0039] FIG. 3 shows a 3-dimensional view of a plasma head 40 comprising the electrode arrangement 10 according to the invention. The plasma head 40 has a plasma exiting tip 49 on a first end 52, a head body 58 and on a second end 53 opposite to the first end 52 a connector 41. The connector 41 comprises a mechanical connector 42 for connecting the plasma head 40 with a handle (not shown). The mechanical connector 42 comprises multiple cylindrical elements 42a-e, which are arranged on the longitudinal axis 46 of the plasma head 40, i.e. are arranged coaxially to each other. The diameter of the cylindrical segments 42a-e is decreasing towards the second end 53 of the plasma head 40. On a front face 47 the connector 41 has a gas connector 48 serving as a gas inlet for the plasma head 40. Further, the connector 41 comprises electrical connectors 43, 44. The first electrical connector 43 is arranged on the cylindrical element 42e and the second electrical connector 44 is arranged in a cylindrical element 42b. In both of the electrical connectors 43, 44 a spring clip extends radially outwards beyond the outer surface of respective cylindrical element 42b, e.
[0040] FIG. 4 shows a sectional view of the plasma head 40 according to FIG. 3 with its male connector 41 inserted in a handle 60 but not snapped into the female connector of the handle 60. From the gas connector 48 at the front face 47 extends a duct 57 towards the first end 52 and exits the plasma head 40 in the plasma exiting tip 49. The duct 57 is sealed to the surrounding when the plasma head 40 is attached to the handle 60 such that only gas can enter through the gas connector 48 and exit through the plasma exiting tip 49. In the area of the connector 41 a hollow cuboid is arranged serving as a support 45 for the electrical connectors 43, 44. Therefore, the support 45 has a basically cuboid shape with a hollow inner core serving as a gas channel. The support 45 is made of a substrate. The support 45 comprises on its outside surfaces conductive tracks each connected with one of the connectors 43, 44. Each of the conductive tracks of the support 45 is connected with an electrical wire 50, 51 connecting the electrical connectors 43, 44 with the electrical connection 27, 37 of the electrode arrangement 10. The electrode arrangement 10 is also arranged in the duct 57. The electrode arrangement 10 is placed in the duct 57 such that the gas can only pass through the gas inlet 13 and subsequently through the plasma cell 11.
[0041] At the first end 52 of the plasma head 40 the plasma exiting tip 49 is fluidly connected with the duct 57. In the shown embodiment, the plasma head 40 is built as a separate part being interchangeable, i.e. being replaceable. The duct 57 shows a 90 degree turn between the electrode arrangement 10 and the transition to the plasma exiting tip 49. In other embodiments, the plasma exiting tip 49 may be arranged straight on in flow direction, either without a turn or with a predetermined angle. However, a turn of approximately 90 degree may be convenient for the operator, especially for the use as a dental device, where other accessories like drills also have a 90 degree angle.
[0042] FIG. 5 shows a second embodiment of a plasma head 40 with an electrode arrangement 10. In contrast to the embodiment shown in FIGS. 3 and 4, the electrode arrangement 10 is not located in the head body 58 but in the plasma exiting tip 49. The tip 49 is connected via a pivot bearing to the head body 58 and comprises a thumb wheel for rotating the electrode arrangement 10 around its longitudinal axis. The pivot bearing may comprise a circular protrusion extending into a circular notch. The rotational movement is limited by stops to 90 degrees. In one end stop position, as shown, the first and second printed circuit boards 20, 30 are arranged transverse to the longitudinal extension of the head body 58 and in the other end stop position the printed circuit boards 20, 30 are arranged parallel to the longitudinal extension of the head body 58. The printed circuit boards 20, 30 and the spacer 12 are made of a flexible material. The substrate 21, 31 and the spacer 12 are made of e.g. polyimide.
[0043] The flexible printed circuit boards 20, 30 are very thin, generally several tens of μm. In combination with a thin and flexible spacer 12, the tip 49 is easily bendable to left and right direction in FIG. 5. The tip 49 has preferably a rectangular cross section with a width defined by the width of the printed circuit boards 20, 30 which is greater than the height defined by the thickness of the two printed circuit boards 20, 30 and the spacer 12. The ratio of width to height is preferably greater than 5:1, more preferably greater than 50:1, further preferably greater than 100:1. Such a design results generally in higher stiffness against bending in direction of the width than in direction of the height. The pivot bearing improves the handling during a procedure with a non-symmetrical cross section by allowing the user to align the tip 49 for example with the tooth pocket to be treated.
[0044] The head body 58 comprises also a connector 41 (not shown), a duct 57 for guiding the gas towards the plasma cell in the plasma exiting tip 49 similar or identical to the duct 57 shown in FIG. 4 and an electrical wiring for the first and second electrode. The first electrical line 50 is connected to the electrical connection of the first printed circuit board 27 and the second electrical line 51 is connected to the electrical connection of the second printed circuit board 37.
[0045] A third embodiment of a plasma head 40 with an electrode arrangement 10 which is shown in FIG. 6 differs from the second embodiment of FIG. 5 in that the plasma exiting 49 is not rotationally attached to the head body 58. The tip 49 is attached in a fixed rotational position to the head body 58.
[0046] FIGS. 7 a-e show alternative embodiments of the plasma exiting tip 49. The plasma exiting tip 49 of FIGS. 7a-c are passive tips and the ones of FIGS. 7d and 7e are active tips having one or two electrodes. In FIG. 7a, the plasma exiting tip is made of a straight pipe particularly made of polyimide. In FIGS. 7b and 7c, the plasma exiting tip 49 comprises two sheets 54, 55. In the embodiment according to FIG. 7b, the two sheets are connected at opposite ends by spacers 56. Accordingly, the plasma exiting tip 49 has a rectangular cross section with a rectangular duct inside. In the embodiment of FIG. 7c, the two sheets 54, 55 are made of a film, e. g. a polyimide film. The two films are attached to each other at their longitudinal sides. The two sheets may be attached to each other by welding or gluing. Between the longitudinal sides a channel is built. The cross-section of the channel may be pre-formed and/or flexible.
[0047] The tip 49 of FIG. 7d comprises two sheets 54, 55. Sheet 54 is formed by the substrate 21 of the first printed circuit board 20 and is coated with a conductive track 22 on one side facing towards the plasma cell 11 and serving as first electrode 54a. Sheet 55 is formed by the substrate 31 of the second printed circuit board 30 and is coated with a conductive track 32 on one side facing towards the plasma cell 11 and serving as first electrode 55a. The two printed circuit boards 20, 30 and preferably the two substrates 21, 31 are connected to each other on their lateral sides via the spacer 12, 56. The cross section of the tip 49 is generally rectangular wherein the dimensions of width and height may vary depending on the intended use. In the shown embodiment, the cross section is square. The two substrates 21, 31 and the spacer 12, 56 are preferably flexible and more preferably made of polyimide. The active tip 49 may also be made of rigid substrates 21, 31 and a rigid spacer 12, 56.
[0048] In the embodiment of FIG. 7e only the sheet 54 forming the first substrate 21 is coated with a conductive track 22 at least in the area of the gas outlet 14. The second sheet 55 may be made of the same material as the first sheet 54 or of a different material. The spacer 56 and the first printed circuit board 20 have the same length, i.e. protrude equally from the head body 58 (not shown). The second sheet 55 is recessed with regard to the spacer 12, 56 and the first printed circuit board 20 such that the first conductive track 22 serving as first electrode 55a is exposed. The second electrode (not shown) may be provided on an object to be treated, e.g. a metal implant or a human/animal body. The electric discharge is formed between the first electrode 54a and the second electrode leading to a plasma generation directly at object to be treated. It may be understood that the embodiment show in FIG. 7e differs from the other embodiments in that it contains only one electrode in the plasma head 40. A person skilled in the art would understand that all modifications and variations described with regard to the previous embodiments may be applied to the present embodiment with only one electrode.
LIST OF REFERENCE NUMERALS
[0049] 1 plasma jet device
[0050] 10 electrode arrangement
[0051] 11 plasma cell
[0052] 12 spacer
[0053] 13 gas inlet
[0054] 14 outlet
[0055] 20 first printed circuit board
[0056] 21 substrate of the first printed circuit board
[0057] 22 conductive track of the first printed circuit board
[0058] 23 exposed surface of the first printed circuit board
[0059] 24 coating of the first printed circuit board
[0060] 25 groove of the first printed circuit board
[0061] 26 finger-shaped projection of the first printed circuit board
[0062] 27 electrical connection of the first printed circuit board
[0063] 30 second printed circuit board
[0064] 31 substrate of the second printed circuit board
[0065] 32 conductive track of the second printed circuit board
[0066] 33 exposed surface of the second printed circuit board
[0067] 34 coating of the second printed circuit board
[0068] 35 groove of the second printed circuit board
[0069] 36 finger-shaped projection of the second printed circuit board
[0070] 37 electrical connection of the second printed circuit board
[0071] 40 plasma head
[0072] 41 connector
[0073] 42 mechanical connector
[0074] 42a-e cylindrical segments of the mechanical connector
[0075] 43 first electrical connector
[0076] 44 second electrical connector
[0077] 45 support
[0078] 46 axis of the cylindrical elements
[0079] 47 front face
[0080] 48 gas connector
[0081] 49 plasma exiting tip
[0082] 50 first electrical line
[0083] 51 second electrical line
[0084] 52 first end of the plasma head
[0085] 53 second end of the plasma head
[0086] 54 first sheet
[0087] 54a first electrode
[0088] 55 second sheet
[0089] 55a second electrode
[0090] 56 spacer of the tip
[0091] 57 duct
[0092] 58 head body
[0093] 59 thumb wheel
[0094] 60 handle
