US2071561A - High frequency apparatus - Google Patents

Description

1937- P. P. MUSKET ET AL. 2,071,551

HIGH FREQUENCY APPARATUS Filed Aug. 22, 1933 4 Sheets-Sheet 1 Feb. 23, 1937. MusKE-r Er AL 2,071,561

HIGH FREQUENCY APPARATUS Filed Aug. 22, 1933 4 Sheets-Sheet 2 1937- P. P. MUSKET ET AL HIGH FREQUENCY APPARATUS Filed Aug. 22, 1933 4 Shuts-Sheet 4 Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE HIGH FREQUENCY APPARATUS Application August 22, 1.33, Serial No. 686,237

4 Claims. (Cl- 171-242) More particularly the invention relates to a high frequency apparatus for therapeutic and surgical purposes.

It is the general object of the invention to provide a new and improved high frequency apparatus which is stable in operation and may be readily controlled.

Another object is to provide such an apparatus embodying a patient's circuit provided with inductive control.

Another object is to provide such a high frequency apparatus with a simple and readily operable control, a single variable inductance being provided in the patients circuit for tuning the circuit.

Another object is to provide a new and improved control means embodying a variable inductance having a coil and a movable contact, and means for reducing the voltage in the turns being commute-ted.

In pursuance of the foregoing objects the invention, in the form chosen for purposes of disclosure, is embodied in a high frequency apparatus particularly adapted for diathermy treatments, and other therapeutic and surgical purposes.

Other objects will become readily apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a front elevation of an apparatus in which a preferred form of the invention is incorporated, illustrating the control panel and cabinet. I

Fig. 2 is a plan view of the oscillator of the apparatus of Fig. 1, viewed from the rear, mounted on the top shelf in the cabinet.

Fig. 3 is an end elevation of the oscillator looking at the right-hand end of Fig. 2.

Fig. 4 is an enlarged fragmentary section through the inductive control means.

Fig. 5 is a fragmentary section along the line 6-8 of Fig. 4.

Fig. 6 is a circuit diagram.

While the invention is susceptible of embodiment in many different forms, we have shown in the drawings and shall herein describe in detail one such embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the preferred form illustrated in the drawings, the invention is embodied in an apparatus arranged to produce upwards of ten million cycles in the patient's circuit. This apparatus is enclosed in a cabinet 2|) (Fig. 1) and comprises generally a high frequency oscillator (Figs. 2 and 3), indicated by a bracket a in Fig. 6, rectifying and transforming apparatus, indicated by a bracket b in Fig. 6, and a patlent's circuit indicated by a bracket 0 in Fig. 6. The parts are preferably mounted on a frame which is withdrawable as a unit from the rear of the cabinet, the frame having a shelf ii on which the oscillator is mounted, and the rectifying and transforming apparatus on the lower shelves. The manually operable control members and indicating devices are preferably mounted on a panel 24, which is carried on the frame so as to be withdrawable therewith.

Referring more particularly to Fig. 6, the oscillator and patient's circuits incorporated in the apparatus will first be described, with reference to the diagrammatic representation. The physical arrangement of the parts will be described more fully hereinafter. The oscillator is illustrated as comprising a pair of vacuum tubes 36 and having filaments I and f. grids g and g, and plates 9 and 9', respectively. The two filaments are connected in parallel, and are connected across a secondary Si of a transformer T by leads 3| and 32. The grids are connected to a grid oscillating circuit by leads 33 and 34, said circuit comprising an inductance coil Lg, and condensers Ca and Ca connected in series with each other (preferably having a common plate, as described more fully hereinafter), and connected in parallel with said inductance coil by leads and 36. A grid leak resistance 31 is connected between the midpoint of the coil La and the mid-point of the condensers Ca and Cd. The plates p and p are connected to a plate oscillating circuit by means of leads 39 and 46, said circuit comprising an inductance coil Lp, connected in parallel with condensers Cp and Cp, (which are connected in series with each other, preferably by having a common plate), by leads 4| and I.

In the preferred form of the invention the grid circuit condensers Ca and Co have a common plate which is formed integrally with a common plate 45 of the plate circuit condensers Cp and Co. The common condenser plate may be grounded in some instances, By-pass condensers 46 and 46' are herein connected between the filament leads and the condenser plate 45, 45'. If desired, a pilot lamp l'l, shunted by a by-pass condenser 48, may be connected across the filament supply leads 3| and 32 by leads 49 and 50. The oscillator'is connected tothe rectifying and transforming apparatus by means including leads and 52, these leads having high frequency choke coils 53 and 54 therein, respectively.

The patients circuit 0, as illustrated in Fig. 6, has a capacity coupling 55 with the plate oscillating circuit of the oscillator, and has a variable inductance 56 for tuning the circuit and thereby adjusting the current therein. The variable inductance is shown in the form of a coil 51 provided with a movable contact 58, a lead 59 connecting one end of the coil to the capacity coupling and a lead 60 connecting the movable contact 58 to a patients terminal E. A two scale load milli-ammeter MA is preferably included in the patents circuit, the milliammeter having a common terminal connected to the capacity coupling by a lead 6I, and low and high scale terminals connected respectively to patients terminals E and E" by leads 62 and 63. Preferably the lead 62 has a fuse 65 therein. Thus by connecting electrodes to the patients terminals E and E the low scale of the milli-ammeter would be in use, and by connecting electrodes to the terminals E and E the high scale would be in use. The terminals E, E and E may be in the form of sockets, as shown in Fig. l, to permit suitable electrode leads (not shown) to be connected detachably thereto. Preferably a fixed condenser 64 is connected in the patients circuit in parallel with the capacity coupling 55. This condenser provides a basic capacitance such that when electrodes, having the largest capacity commonly encoun tered in treatment, are employed, the patient circuit may be tuned with the variable inductance near zero. By the use of such a condenser the patient circuit is rendered very stable and highly efficient because of the reduced losses in the inductance. The condenser 64 is preferably a mica condenser in order that it may have a large capacity without attaining undue bulk.

The oscillator, as illustrated in the drawings, and particularly in Figs, 2 and 3, is of simple and efflcient construction. As will be readily apparent from these views, the elements of the grid and plate oscillating circuits are symmetrically arranged so as to eliminate to a large extent the need for separate leads between the parts and minimizes the length of leads, where leads are provided, and minimizes and balances leakage capacity. The tubes 30 and 30 are spaced laterally and mounted in vertical positions so that the grid leads or and gr extend from the top thereof, and the plate leads pa: and pr extend from corresponding projecting side portions of the tubes. The tubes are detachably mounted in suitable sockets 68 on the supporting shelf 2|. The common plate 45, 45 of the grid and plate circuit condensers extends centrally between the tubes, as shown most clearly in Fig. 2. This plate cooperates with a pair of condenser plates 18 and positioned parallel to and adjacent the right-hand end of plate 45 (Fig. 2) to form the pair of grid circuit condensers Cg, Cg (Fig. 6), which are thus connected in series. The grid leads ya: and gx' are connected directly to posts H and 1| (Fig. 3) on the plates 10 and 10'. The grid circuit inductance coil Lg is mounted on a pair of insulators 12 by means of L-shaped members 13 and screw and nut devices 13', and is positioned above the grid circuit condensers so as to extend transversely over the condensers. The ends of the coil are connected to the condenser plates 10 and 10 by means of short connections 14. The grid leak resistor 31 is positioned vertically at the end of the shelf in substantially the plane of the common condenser plate 45 and is connected at one end by a short lead to the plate 45, and at its other end by a short lead 16 to a central point on the-coil.

The plate oscillating or tank circuit condensers C50 and Cp have plates 80 and 80' positioned on the opposite sides of and adjacent the common plate 45" (Fig. 2), so that said condensers are in effect connected in series. The plate leads par and ms are connected directly to these condenser plates. The inductance coil Lp is mounted on the upper ends of insulators 8| by means of L-shaped members 82 and screw and nut devices 83, and has its ends connected by short connections 84 to the condenser plates 80 and 60' respectively.

The capacity coupling between the patients circuit and the plate oscillating circuit of the oscillator, as illustrated most clearly in Figs. 2, 3, and 6, includes a pair of plates 90 and 90' which are positioned parallel to the common condenser plate 45' and intermediate the lefthand end of this plate (Fig. 2), and the adjacent condenser plates 80 and 80. The plate 98 is connected by means of the lead 59 to one end of the variable inductance coil 51, whereas the plate 90 is connected by means of the lead 6I to the common terminal of the milliammeter MA. The condenser 64 (Fig. 6) connected in parallel with the patients circuit, is shown as comprising portions of the plates 90 and 90' (Fig. 2), a pair of plates 9| and M and an intermediate plate 93, the plates being separated by sheets of mica or other suitable dielectric 92, 92' and 94, 94'. The plates 9| and 9| are preferably formed integrally with a connecting portion 9|". As illustrated herein the plates 90 and 90' together with the other parts of condenser 64 are mounted as a unit directly upon the shelf 2| by means of a. plurality of L-shaped members 95, and are thereby supported independently of the plate oscillating circuit elements.

The inductance coil 51, which is herein provided in the patients circuit for the purpose of varying the current and tuning the circuit, is mounted in a horizontal position on the back of the panel 24 (Figs. 2, 3, and 4) by means 01 end brackets I60, which also carry a pair of slide rods I6I extending longitudinally of the coil. Preferably a pair of sliding contacts 58 are provided, these contacts being operable by means including a knurled knob I62 positioned in front of the control panel 24. The knob I62 is non-rotatably secured to a shaft I63, the shaft being rotatably mounted in a bracket I64 which is suspended from the end brackets I66 by means of bars I64. A gear wheel I65 is secured to the shaft and meshes with a rack I66 which is slidable longitudinally beneath the coil. The contacts 58 are secured to a ring or band I61 by means of resilient mounting members I68, the ring I61 being carried on a member I69 which is slidable on the rods I6I. The rack I66 is secured to the sliding member I69. Thus by rotating the knurled knob I62 the contacts 58 may be moved over the coil turns.

Preferably the ring I61, as illustrated most clearly in Figs. 2, 4, and 5, is of sufficient length so as to overlie a plurality of turns on the coil 51. This ring is formed of metal and serves as a means for reducing the voltage in the turns being commutated by the contacts 84 for the purpose of preventing sparking and pitting of the contacts. The ring, of course, moves with the contacts longitudinally of the coil and provides for efficient operation of the variable inductance.

The rectifying and transforming apparatus for supplying a pulsating direct current to the oscillator through the leads II and '2 will now be described with particular reference to the circuit diagram in Fig. 6. In the form illustrated in the drawings. this apparatus comprises a plurality of rectifier tubes I44 and I44 having filaments III and plates I42. The filaments are connected across individual secondary windings 82 and 82' on the core Tc of the transformer T, the primary winding P of which is arranged to be excited by 110 volt 60 cycle alternating current as hereinafter more fully described. The plates "2 of the tubes I are connected to the opposite ends of the secondary S3 of a transformer T by means of leads Ill and I44, and are connected to the mid-points of the secondary transformer windings 82' by means of leads I" and I. The plates of the tubes III are connected together by a lead I" and to one side of a plate current milli-ammeter MA by means of a lead I. The other terminal of the milli-ammeter is connected to the mid-point of the transformer secondary Si by means of leads I and H0. The mid-points of the transformer secondaries B2 are connected together by leads III and H2 and to one side of a condenser III by a lead H4. The other side of the condenser H2 is connected by a lead III to the iunction of the leads I" and III. The oscillator leads II and '2 may be connected to the leads I and H4 as illustrated.

The primaries and secondaries of the transformers T and T are proportioned so as to provide the necessary voltages for the filaments and plates of the various tubes. As mentioned hereinbefore the primary P of the transformer T, in the preferred form of the invention, is adapted for connection to a 110 volt 60 cycle alternating current supply. This is also true with respect to the primary P of the transformer T. The transformer primary P, as illustrated in Fig. 6, has one end connected by means of a lead I24 to one end of a resistor I2I of a filament rheostat FR. a movable contact I22 of the rheostat being connected by a lead I24 to one terminal I24 of a filament control switch FC. The other terminal I24 of the switch FC is connected to one end of a high frequency choke coil HFC, the other end of the choke coil being connected to a line terminal I28. The other end of the transformer primary P is connected by leads I2! and I26 to a similar high frequency choke coil HFC', the other end of which is connected through a suitable fuse I21 to a second line terminal I24. A volt meter V is preferably connected across the transformer primary by leads III and I32.

In order to insure proper heating of the rectifier tube filaments prior to the energization of the plate circuits, one end of the primary P of the transformer T is connected to a time delay switch TDS by a lead I". The time delay switch may be of any preferred form and preferably embodies a heating element operable when current first flows in the primary circuit of the transformer T so that there will be a definite lapse of time after the filament current switch I'CisclosedbeforetheprimaryP'isexcited. The

other end of the primary P is connected to one side of a circuit breaker CB by a lead I40, the other side of the circuit breaker being connected by a lead I to one end of an adjustable impedance coil I42. A movable contact I43 is connected by a lead I44 to one terminal I45 of a plate current switch PC, the other terminal I4. of which is connected to one side of the filament current switch FC by a lead I41. Preferably a resistor I44 is shunted across the circuit breaker CB so that if the current in the plate circuit exceeds a predetermined value the circuit breaker, upon opening, will automatically insert the resistor I4. in the circuit so as to limit the current. (The circuit breaker may be closed by a handle CB, Fig. 1). It will be apparent that the current to the primary P also passes through the filament current switch PC so that it is necessary first to close the filament current switch. However, the time delay switch is also included to delay properly the excitation of the rectifier tube plates. For convenience in operation, a foot operated switch I" is connected in parallel with the plate current switch PC.

when used for diathermy treatments, condenser type electrodes are preferably used, i. e., electrodes spaced from the patient by a suitable dielectric. The electrode leads are connected to the terminals E and E if it is desired to use th low scale of the load milli-ammeter, and are connected to the terminals E and E" if it is desired to use the high scale of the meter. If low currents are being used the circuit breaker CB may be left open. the circuit breaker being generally closed when relatively high currents are used so that if there should be a marked increase in current above the value at which the controls are originally set, the breaker will open and insert the resistance I42 in the plate circuit. After the electrodes have been connected and properly adjusted to a patient. the filament current switch PC is closed and the voltage across the primary P of the transformer T properly adjusted by means of a knurled knob I (Fig. 1) which is operable to adjust the contact I22 (Fig. 6) of the filament rheostat FR. After sufiicient time has elapsed to permit the filaments to heat properly the plate circuit of the rectifier may be closed either by means of the switch PC or the foot operated switch. I50. In Fig. 1 there is shown one part Iii of a detachable connecter secured to the panel 24, this part having its contacts suitably connected in parallel with the terminals of the switch PC. The other part of the connecter (not shown) may have suitable flexible leads connected to a foot switch so as to enable the operator to close and open the plate circuit of the rectifier by means of his foot if this is found more convenient. Should the plate circuit be closed before sufilcient time has elapsed the time delay switch TDS functions to hold the plate circuit open for the requisite period. As soon as the plate circuit is closed the oscillator will commence to operate after which the patient's circuit may be tuned by means of the variable inductance 56, the operator manipulating the knurled knob I62 for this purpose. The variable impedance I42, I43 may be adjusted for changing the current, a knurled knob I52 being mounted on the front of the panel 24 (Fig. 1) for this purpose.

We claim as our invention:

1. A variable inductance comprising, in combination, a coil. a contact movable longitudinally of the coil and in engagement with the turns thereof, and means for reducing the voltage across the turns of the coil being engaged by said contact, said means comprising a metal ring surrounding the coil in spaced relation thereto and movable longitudinally thereof with said contact and overlying a plurality of turns of the coil, said contact being carried within said ring.

2. A variable inductance comprising, in combination, a coil, a contact movable longitudinally of the coil and in engagement with the turns thereof, and means movable with the contact for inductively reducing the voltage across the turns of the coil being engaged by said contact.

3. A variable inductance comprising, in combination, a coil, a metal ring surrounding the coil overlying a plurality of turns of the coil and movable longitudinally thereof, and a plurality of circumferentially spaced contact members carried within said ring and in engagement with the turns of the coil.

4. A variable inductance comprising, in combination, a coil having a plurality of turns spaced longitudinally thereof, a metallic ring surrounding the coil and having contact with the turns thereof, said ring overlying a plurality of turns of the coil, and means supporting said ring for sliding movement longitudinally of the coil.

PETER P. MUSKET. DONALD E. RICHARDSON.

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