US 3080509 A
Abstract available in
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Description (OCR text may contain errors)
H. C. ROWE March 5, 1963 RELAY Filed Oct. 14. 1957 2 Sheets-Sheet 1 F l G.
INVENTOR. HARRY C. ROW BY E t 1 m7 ATTORNEYS H. C. ROWE March 5, 1963 RELAY 2 Sheets-Sheet 2 Filed Oct. 14, 1957 FIG. 5.
INVENTOR. HARRY C. ROWE ATTORNEYS 3,titi,509 RELAY Harry C. Rowe, Berkeley Heights, NJ., assignor, by nresne assignments, to adio Cores, Inc, Gal: Lawn, Ilh, a corporation of Illinois Filed Get. 14, 1957, Ser. No. 690,017 6 Claims. (Cl. 317-44?) This invention relates to a relay, and has particular reference to a control relay which is highly sensitive to touch by a person or by some other contact involving an extremely small current flow.
It is desirable for many purposes to provide a control relay arrangement to close or open one or more electrical circuits merely by the casual touch of a person.
Such relay circuits have been provided in the past but have quite generally been lac ing in sensitivity or have required considerable and complex circuitry. In accordance with the present invention a very simple control is provided which utilizes the impedance to ground of the body of the person etrecting operation and is operated by the use of the commercial alternating current supply. In accordance with the invention the control utilizes as its principal elements a miniature thyratron together with a small heater-operating transformer, providing a deliberate ground, and a small relay, the other components being merely small passive elements. The entire control may be located in a small housing which may, if desired, be portable and plugged into any alternating current supply outlet for use. Despite its simplicity it is completely safe and highly reliable despite weather conditions. Alternatively there may be provided a replaceable plug-in unit arranged for association with fixed external circuitry.
Many uses may be found for the control: it may be used, for example, as an alarm against burglary or tampering, as a safety control in connection with machinery or other equipment, for the purpose or" remote control of electrical equipment, or the like. it may also be used for liquid level indications employing the conductivity of the liquid, even if the conductivity is extremely low.
One object of the invention is the provision of a con trol of the general type indicated.
Another object of the invention is the provision of an improved relay arrangement utilizing microswitches.
A further object of the invention is the provision of a contact clip particularly suitable for making contacts between removable printed circuit components and printed circuit boards.
Other objects of the invention have to do with the attainment of the apparent from the following description, read in conjunction with the accompanying drawing, in which:
FIGURE 1 is a plan view of one physical embodiment of the invention, a housing being shown in phantom;
FIGURE 2 is a side elevation of the same;
FIGURE 3 is an end elevation of the same;
FIGURE 4 is a wiring diagram showing the electrical connections involved in the control.
FIGURE 5 is a plan view of the plug-in unit embodying the invention;
FIGURE 6 is an inverted plan view or the same, showing a printed circuit arrangement;
FlGURE 7 is a fragmentary section taken on the surface indicatcd at 77 in FIGURE 5; and
FIGURE 8 is a perspective view showing a con-tact clip.
Referring first to FIGURE 4, there is indicated at 2 a thyratron of the type which may be fired under conditions of negative potential of the control grid. Such a thyratron is utilized since, the initiate firing, substantially no current is required to fiow through the control grid. Various thyratrons are available having satisfactory chareneral results indicated and will be acteristics and desirably, for economy of space, the thyratron used is of miniature type such as the GL5663, 6AD4, or 2D21, though larger thyratrons such as the 2050 may be used. The heater leads 4 of such a thyratron are connected to the secondary s of a suitable transformer 8, the primary it! of which is connected through the conductors of a lead cord to a plug which may be inserted in a circuit supplying the conventional or other alternating commercial voltage. The transformer secondary supplies heater current at the required voltage, for example, 6.3 volts or 2.5 volts depending upon the thyratron used.
In accordance with the invention, one of the transformer primary leads, illustrated in FIGURE 4 as the one to the right, is connected to the ground side 14 of the supply line, the other being connected at 12 to the ungrounded side of the line. While alternating current is involved, the diagram in FIGURE 4, for convenience of description, has indicated by positive and negative signs instantaneous dire-ct potentials which exist when there is app-lied to the anode of the thyratron during a half cycle a positive potential with respect to its cathode to put it in condition for firing. Thus there is indicated a positive potential at terminal 14, a negative potential at terminal 12, a positive potential at the left-hand end of the secondary 6 and a negative potential at the right-hand end of this secondary, such potentials arising during the operating half cycle of the alternating supply. The left-hand ends of the primary and secondary of the transformer 23 are connected together and through a small capacitor 16 (which may have, for example, a capacity of about 0.061 microfarad) to the casing of the apparatus which is indicated at 18.
Shunted across the secondary 6 of transformer ii is the potentiometer 20, the adjustable contact 22 of which is connected to the control grid of the thyratron through a high resistance 24 which may be of the order of a megohrn. While an adjustable contact is indicated at 22, in many cases the arrangement providing the control grid bias may be fixed by the provision of a pair of resistors or by a fixed tap on a resistor in the position of 2%. (if desired, the potentiometer 20 may be connected between the transformer secondary terminals in series with a miniature rectifier-filter to provide a DC. bias.)
A high protective resistance 25, for example, of the order of one megohm, connects the control circuit or" the thyratron to a terminal 23 which serves for control as will be hereafter pointed out.
The anode of the thyratron 2 is connected through an anode current limiting resistor 29 and the winding of a suitable relay 3t) to the terminal 14 which is grounded and positive during the operating half cycle. T a relay comprises the movable and fixed contacts 3?. and 34 ar ranged to connect the current source 36 to terminals 33 which may be provided in the form of socket terminals to receive a plug connected to a device which is to be operated. For generality the terminals 36 are indicated as independent, but in most uses of the device these terminals would be connected to the terminals 12 and 14 to supply the commercial supply voltage to the output terminals 38. The relay may be arranged to open rather than close a circuit; or it may control a number of circuits.
A capacitor 40 suitable to prevent chattering of the relay and having, for example, a capacity of 5 microfarads, is shunted across the coil of relay 3h.
In many circumstances it is desired to have the control operate only when contact is made with terminal 23. However, if it is desired to have operation continue after initial tripping of the control, the relay 39 may be provided with a second pair of contacts 4-2 and 44 connected, on one side, through line 46 to the left hand terminal of the secondary of transformer 8, and on the other side through connection 48 and a resistor St to the thyra-tron control grid, the resistor so having a high resistance, for example, of the order of five ruegohms.
As indicated in FIGURES l, 2 and 3, wherein the physical elements are designated by the same numerals as are applied to them in the Wiring diagram of FIGURE 4, the elements in one embodiment of the invention are mounted on a base member 18 which is arranged to be received in a housing 52, the base 18 being secured therein by screws 54. A tab 56 may be provided on the housing for the purpose of hanging it on a wall or elsewhere.
The terminal 2% which projects from the housing through a clearance opening may take the form of a threaded screw or nut by which a wire may be secured. The member forming the terminal is secured to an insulator which may be in the form of a tube providing a housing for the resistor 26.
The operation of the control is as follows:
Assuming first that the portion of the circuit comprising lead 46, contacts 42 and 44, lead -48 and resistor 50 is either missing or open-circuited, the control is such that when the terminal 28 is touched the relay contacts 32. and 34 will be closed, these contacts reopening when the terminal 28 is released and non-operating half cycle of the supply occurs. I
The operating half cycle is one which produces positive potential at grounded terminal 14 with respect to the terminal 12. At this same time the left hand terminal of the transformer secondary '6 will be positive with respect to its right hand terminal. It will be noted that the cathode of the thyratron is connected at the left hand terminal of secondary 6, so that in the operating half cycle a negative bias potential is applied from contact 22 to the control grid of the thyratron. Through the connections illustrated, the positive line potential of the operating half cycle is applied to the thyratron anode with respect to its cathode. The bias applied to the control grid is so adjusted, or initially set, that firing of the thyratron will not occur until the terminal 28 is touched. When the terminal 28 is touched, the capacity of the body to ground, represented by the dotted capacity C, results in the application of a positive increment of potential through resistor 26 torthe thyratron control grid with respect to its cathode, the voltage divider arrangement provided by resistors 26 and 24 producing a substantial positive increment of control grid potential suiiicient to fire the thyr'atron. This does not mean that the control grid necessarily becomes positive with respect to the cathode; only that the negative bias is reduced to the point of firing, the thyratron being desirably of the ty e fired though its control grid is negative with respect to its cathode. The firing of the thyratron energizes relay 3d and produces charging of the capacitor 49 which, through the inactive half cycle discharges through the relay to maintain the relay energized. So long as body contact is made with terminal '28 the relay remains energized to energize the terminals "38. When contact at terminal 28 is interrupted, deionization will occur during the next inactive half cycle, with resulting deencrgization of relay 3t) and opening of the supply -cirwit to terminals 38. 7
Operation as just described will, of course, only occur if the terminal 14 is grounded. However, even when the terminals 12 and 1-4 are reversed with respect to the power line firing will occur if contact is made by the operator with both the terminal 23 and the housing indicated at '18 due to the capacitor at 16 since the potential or" the control grid is, by such connection, brought toward cathode potential. Such operation may sometimes be desired though it is not the most useful operation which involves the utilizing of body capacity C to bring to the control grid of the thyra'tron a substantial fraction of the line potential as apositive firing potential increment.
- If it is desired to have the control remain active. when the terminal 2'8 ,isr'eleased after being touched, the circuit involving the elements 42, 4-4, 46 and E is'provide'd so 7 like, may operate.
that when the relay 30 is initially energized the control grid is connected to the cathode through the resistor 5t This raises the control grid potential positively to a firing potential and the thyratron will then continue to tire in each succeeding active half cycle, bridging over the inactive half cycles resulting from the maintenance of energization of relay 3%] by discharge of capacitor 44 If such a holding arrangement is provided the control may be deenergized in various ways, as by rnomentarily interrupting the supply to terminals 12 and 1-4, by push-button opening of the circuit including the contacts 42, and 44, or in various other obvious fashions.
. Complete safety is provided by the provision of high resistor as :and/ or the relatively small capacitor 16,, since even if a conductive ground contact is made by the person touching the terminal 2'3 the current through the body is held to so small a value as not to be even perceptible. Since tiring occurs with the control grid at negative potential with respect to the cathode, the circuit arrangement need not be such as to provide a grid current.
The compactness of the arrangement will be evident tr'om FIGURES l, 2 and 3. While a portable type of housing is indicated the elements which are involved are so small that in a permanent installation they can be readily enclosed in a conventional junction box or other fixed housing.
It will be evident that many uses may be made of the device. Its application to remote control will be evident. As a safety device it may be so used that unless contact is made with a terminal such as 28 or some conductor connected thereto a power drive-n tool may have its circuit held open so as not to be operable. In connection with such safety arrangement it is often desirable that the two hands of a machine operator should be in definite spaced positions before the tool such as a press, or the In such case use may be made of the device with the terminals 12 and 14 reversed so that -from the electrical standpoint the operator must bridge the terminal 28 and the terminal represented by the housing 18 before tripping of the control can occur to energize the tool.
The control may be used, in particular, as an alarm against burglary or tampering by connecting to the terminal 28 one or more leads running, for example, to a door knob, desk or cabinet lock, or the like. If such leads are shielded, with suitable adjustment of the control grid bias, thyra'tron firing will occur upon the slightest touch connecting an intruder to the terminal 28. In such alarm use it may be desirable to have the holding circuit including the conductors 42 and 44 placed 'so that the alarm connected to the output terminals 38 will give a continuous visual or audible signal which may be either local or remote, as in a guard station, protective agency "or the like. ,v For liquid level control, the terminal 28 maybe in the form ofan electrode engageable by a liquid level. A pair of devices such as described may be used for control of both maximum and minimum levels. Due to the high sensitivity of the device, a very low liquid conductivity will 'sufiice for operation. Levels ofnon-conducting liquids may also be detected by causing them to rise between a pair of condenser plates normally providing a capacity at C insufficient -for operation, but providing due to the dielectric constant of the liquid, a higher capacity at C capable-of effecting operation.
The physical embodiment of the invention heretofore described is particularly for a portable device such as may be used for household or similar purposes. When the device is .tobe used industrially it may be provided most conveniently and advantageously in a plug-in form which will now be described with particular reference to FIGURES ,5 to .8, inclusive. While the circuitry involved may be essentially that shown .in FIGURE 4', the.
I embodiment about ,to be described has the advantage that in the event of any failure a new assembly may be plugged 'ing plate 58 which carries the into a socket providing external connections and, in fact,
the device may be readily repaired, particularly, if the fault lies in the relay. The thyratron may, of course, be readily replaced. The device now to be described is com.- pact and fiat and hence may be readily associated with other devices. Also, it embodies the advantages of utilization of printed circuitry, and, in accordance with the invention, provision is made for associating the various elements of the device with the printed circuitry in a fashion permitting easy assembly and disassembly.
In this embodiment, support is aiiorded by an insulatprinted circuit particularly illustrated in FIGURE 6. In FIGURES 5 and 6 the'elements which correspond to those previously described and shown in FIGURE 4 are designated by the same numerals with primes ailixed, various of these p ysical elements being shown in construction lines in FIGURE 6.
The printed circuitry need not be described in detail since the wiring diagram shown in FIGURE 4 applies. However, it does lend itself to the making of various selective connections by the use of jumpers, and provides for easy assembly of the physical components. For this purpose, the plate 58 is provided by printed circuit technique with a series of contact tabs distributed along one edge thereof which are adapted to be received in a known type of socket provided with prongs corresponding to the tabs, the prongs being connected to external circuitry. T he tabs may be briefly referred to as follows:
I The tabs 66 and 62 which will normally be 110 volts. Tab 64 provides for grounding, if required, of the relay and transformer frames. Tab 66 is connected to the cathode and heater of the thyratron. Tab 63 provides, if desired, for the input or" an external bias to the grid resistor. likewise provides for an adjustable external bias. Tab 72 is the control connection to the input of the resistor 26 and corresponds to terminal 28 previously described. Tab 74 provides a connection, if desired, which furnishes 6.3 volts alternating with respect to the cathode.
At '76 there is provided a polarizing slot engageable with a projecting element on the plug receptacle to insure that the relay assembly is inserted in proper fashion.
Tabs 78 to 94 provide external connections for a set of three microswitches which form part of a relay as described hereafter. Tabs 78, 3d and 82 are the common connections for these microswitches. Tabs 84, 8d and Mt may be normally open contact connections, while tabs llti, and 94 are normally closed contact connections.
As illustrated, the tabs just mentioned are connected by the printed circuitry to conducting areas surrounding square openings 96 which receive contact clips which will be shortly described. Similar square openings and 1% provided with conducting boundaries are arranged to furnish connections to the relay coil. Slots N2 and litl l in plate 53 are arranged toreceive ears in the relay assei'nbly to hold it in position. A circular opening at the also provided with a conducting boundary is arranged to receive a screw to secure the relay assembly to the plate se. The circuit lead connected thereto serves to provide a ground connection through tab 64.
In accordance with the invention spring contact clips indicated generally at 1&7 in FIGURE 8 are arranged to be received in the square openings such as as, 98 and 1th), and in turn receive contact pins on the microswitches and on the relay assembly. Each of these clips has a square base 1% from which extend in parallelism arms 1:10 and 112 which are arranged to fit the square openings. These arms are then divergent outwardly and convergent inwardly as indicated at 114 and 116, and at their upper ends diverge as at 118 and 126 for the ready reception of contact pins. It will be evident that these clips may be arranged in alternative 98 positions in the square openings. Either by direct or dip soldering they may then altord connections to the conducting areas receive the alternating power input Tab 7% insulating spool of the winding of the printed circuitry surrounding the square holes. Desirably when in place they project only slightly below the bottom surface of the plate 58. When pins are inserted to make contacts they are sprung outwardly to provide a secure mechanical arrangement which will hold despite any weakness in the soldering. As will be evident, the clip arrangement just described is of much broader application than to the relay arrangement herein described, and is considered to be an invention per se.
The relay assembly is particularly shown in FIGURES 5 and 7. This comprises a generally U-shaped frame indicated at 122 provided with ears 123 arranged to be engaged within the slots 1&2 and 104 to be held by the underside of the plate 58. The lower cross portion of this frame at 124 carries the relay magnet comprising the core 126 and Winding 128, the upper flanges of the frame at providing part of the magnetic circuit. The armature 130 is pivoted at 13-2 in ears of the frame and is limited against undue outward movement by the head of a screw 134 threaded into the core 126. A screw 136 is threaded into the core 126 and projects through .the opening 106 beyond which it is engaged by the nut 13S whereby the frame is secured in place and electrical contact is also made with the conductive area surrounding the hole 106. Pins ll ltl are carried by the flanges of the 12S and are connected to the coil terminals, being arranged for reception in the contact clips mounted in the openings 98 and 100. As illustrated, three conventional miniature microswitches 142 are used as the contact making or breaking elements of the relay and have their operating buttons 14d engageable by adjustable screws 146 which are threaded through lock washers 148 retained in place by undercut projec tions 143 formed on the armature 130. The microswitches 142 are secured in the relay frame by screws 15d extending through openings therein, there being interposed spacers to maintain their buttons 144 in alignment with the screws 3.46. The microswitches are provided with projecting pins 160, 162 and 164, which are received in the spring clips located in the square holes 96. By adjustment of the screws 146 the relays may be caused to operate in desired sequence or substantially simultaneously when the relay is energized.
The provision of a relay utilizing microswitches for the making and/ or breaking of contacts is also a part of the invention which is adapted for more general use. Since microswitches of this type commercially made are highly reliable, the resulting type of relay utilizing them is particularly reliable, the contacts being enclosed and not subject to faulty operation due to dirt or corrosion. Only minute movements of the armature are necessary for completely reliable making or breaking of contacts. Furthermore, if one of the rnicroswitches becomes faulty, replacement may be readily made. It will also be evident, that while three microswitches are shown, any desired number may be used, the relay being thus arranged for quite universal connections. The entire relay assembly may be readily disassociated from the printed circuit and replaced in the event that the coil circuit is burnt out or accidentally opened.
As has been stated heretofore, the circuitry involved in the last described modification may be identical with that illustrated in FIGURE 4 or may be slightly changed by suitable connections to the printed circuit, for example, to provide external bias, or the like. In the event that holding is desired, one of the microswitches may provide the contacts illustrated at 42 and 44 in FIG- URE 4.
It will be evident that the modification last described may be used in all of the fashions discussed above, and is particularly adaptable to industrial or similar use where it may be required to be associated with other circuitry.
It is to be understood that t e invention is not to be regarded as limited except as required by the following claims.
7 'Whatis claimed is: 1. A control device comprising a gaseous electron tube having an type adapted to be fi'red under conditions of negative .potential of the control grid with respect to the cathode, a
trans-former having its primary arranged for connection to an alternating supply line with a grounded side, means connecting one end or the primary of said transformer to the anode of the electron tube, means connecting to gether and to the cathode of the electron tube the other end of the transformer primary and that end of a secondary thereof which is at any inst-ant polarized oppo- 'sitely to the last mentioned end of the transformer primary, means connected to said transformer secondary to supply an alternating current non-firing bias potential to said control grid when the electron tube anode is positive with respect to its cathode, a control terminal connected to said control grid, and means actuated by firing of said electron tube, said device being such that the capacity :to
ground of -a person contacting said control terminal will effect firing a: the electron tube when the grounded end of the transformer primary is connected to the electron tube anode and is positive with respect to the ungrounded end of the transformer primary.
2. A control according to claim 1 in which a high fesista'nce is connected between said control terminal and said control grid.
anode, a cathode and a control grid and of the the electron tube are enclosed in a conductiye housing. '6. A control according to claim 5 in which the housing is connected to the ungrounded side of the supply line through a capacitor.
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