US2695400A - Electric signaling device - Google Patents

Description

Nov. 23, 1954 K. sNlTJER ELECTRIC SIGNLING DEVICE l Filed Feb. 19. 1953 INVEIYTOR. Kor/alms Snif/7er UnitedStates Patent ELECTRIC SIGNALING DEVICE Komelius Snitjer, Arnhem, Netherlands, assigner to American Enka Corporation, Enka, N. C., a corporation of Delaware Application February 19, 1953, Serial No. 337,827

Claims priority, application Netherlands March 5, 1952 Claims. (Cl. 340-213) The invention relates to an electric signalling system, provided with at least one signalling apparatus for attracting the attention of a machine operator or attendant, and at least one visual, location signalling apparatus. The attention signalling apparatus is connected in such a way that it can be disconnected independently from the one or more visual, location signalling apparatus, and is immediately ready for a new warning.

On such a signalling device, where a large number of warning signals may take place, the following requirements must be met:

l. Every warning must be indicated visually (for example by means of a signal lamp) independently of the other ones, and must remain visible as long as the warning lasts.

2. At every arbitrary Warning, at least one attention signalling apparatus must be put in operation, for ex ample a signal horn.

3. Immediately after observation and locatlon of the warning by means of the signal lamp indicator, it must be possible to switch the attention signalling apparatus off. y

4. Immediately after switching-olf, the attention signalling apparatus must be ready to signal a new warning.

In order to be able to meet the above requirements, previously each signal transmitter required either two normal relays, each with four contacts, or one special relay,

which had to be provided with so-called self-wiping conv tacts. A relay of the later type is either not reliable, or very expensive.

As is generally known, every relay, however Well it may be constructed, is a weak point in the circuit which it is used because of the required openingand closingcontacts, coils, etc., especially when the circuit -must be set up in relatively inaccessible places. Moreover, a reliable relay is an expensive piece of equipment.

The invention has, as an object, the provision of an electric signalling device at reduced costs, and, what isl ing terminal of which-is connected with the cathode of the discharge tube. This device has the advantage of not containing extra moving parts or contacts. If desired. after having been mounted, the component parts, which have very small dimensions and a practically unlimited life, can be embedded in artificial resin, or sprayed with a thick layer of acid-resistant paint, so that they can be set up in the most unfavorable atmosphere.

The resistance with a large negative temperature coei'li cient (-3 to 4.5% per C. at 20 C.) are so-called semiconductors. With increasing temperature, the resistance decreases rapidly and considerably.

According to the invention the signalling system can be provided having a transformer with a secondary winding with a center tap, the terminals of which are, via rectiers,

connected with the terminals of a resistance, l*the center of which is connected with the center tap of the secondary winding, whilethe positive terminal of the resistance is, via a contact and a relay winding of the attention signalling apparatus, connected with the anode ofa discharge tube.

`6,0 coeicient is provided in the signal circuit, the connect-4 minals 25, 25', 25" connected with the connecting terminal 21 of the leakage 2,695,400 Patented Nov. 23,1954

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The cathode of the discharge tube is connected with the center tap and the grid of which is, via a grid resistance, connected with a point of the resistance which is negative with respect to this center tap, and the cathode is connected with this center tap and a supply line.

A preferred embodiment of the signalling system according to the invention is characterized in that one of the terminals of each signalling device is connected with the side of the line which is connected with the cathode of the discharge tube, the other terminal being connected on the one hand via a resistance with the other side of the line, and via a signal lamp with the first side of the line, while moreover, a line goes from this other terminal to the cathode of the discharge tube via a resistance and a resistance with a large negative temperature coeflicient, and the grid of this discharge tube is connected, via a resistance, with the connecting terminal of the resistance with a large negative temperature coellicient.

The invention will be further described below with reference to the drawing, in which, by way of example, an embodiment of the signalling system according to the invention is shown.

In the drawing, A and B indicate the conductors of an alternating current supply line, between which a voltage of, for example, 220 v. exists. These conductors are connected with the primary winding of a transformer 2, the secondary Winding of which has a center tap, the terminal voltages between the ends of this secondary winding and this center tap each amounting to, for example, 300 v. A rectifier 3 has been inserted in each of the conductors which are connected with the outer terminals of the secondary winding, smoothing condensers 4 being provided between these conductors and the center tap. Resistances 5, each of, for example, 50 k. ohm, furnish a load for limiting the voltage in the normal operating position, when no current is consumed.

The center tap of the secondary winding of the transformer is connected with the cathode 6 of a thyratron 1, and, via a conductor 18, with one side of the supply line B. The end of the resistance 5 which is positive with respect to this center tapping is connected with the anode 10 of the thyratron 1 via a disconnecting button 7, an adjustable resistance 8 and a relay coil 9 for controlling the operating circuit of an attention signalling apparatus 22, for example, a signal horn.

Via a resistance 11l and a leakage resistance 14, the grid of the thyratron 1 is connected with an adjustable tapping of the lower resistance 5, which point is negative with respect to the center tapping of the transformer, so that the latter has an adjustable negative pre-voltage with regards to the cathode.

The signalling system is further provided with a number of signal circuits, each of which containing a signal actuator 15, 15', 15" etc., for example, a contact of a pressure gauge, rheostat, thermometer, magnetic switch of a motor, which lsignal actuators are on one side connected with one side of the supply line, B. The other connecting terminal of each signal actuator is connected with a terminal of a resistance 16, 16', 16" etc.,.as well as with a terminal 17, 17', 17" etc. of a neon signal lamp27, 27', 27" etc. The other terminals of these resistances are connected with the other side of line, A. The second terminal 19, 19', 19" etc. of each signal lamp is connected with the conductor 18. The terminals 17, 17', 17" etc. of the signal lamps 27, 27', 27" etc. and of the resistances 16, 16', 16" etc., are each, via a resistance 20, 20', 20" etc., connected with a connecting terminal 24, 24', 24 etc. of a resistance 12, 12', 12" etc., as well as of a resistance 13, 13', 13" etc. The teretc. of these resistances are resistance 14, the other terminal 26, 26', 26" .,etc. of the resistance 13, 13', 13'l etc. being connected with the circuit 18. The resistances 13, 13', 13" etc. are resistances with a large negative temperature coeicient. v

As the screen grid `of the thyratron is not used, this screen gridis via resistance 23 connected with the cathwith the cathode of the thyratron, is, via the circuit 13,

-connected with the other terminal 19, 19', 19" etc. of each of the signal lamps, so that the `points 17, 17', l17" land the points 19, 19', 19" 'have the same potential, so that the signal lamps-cannot burn.

When a disturbance occurs, for example because the contact `15, 15', 15" etc. of one of the signal circuits is opened, this signal circuit is Ainterrupted or gets grounded due to corrosion, the Apoint 17 obtains approximately the same potential as the -line A. Consequently, there is a sutiicient voltage difference between the connecting terminals 17 and 1.9 of the signal lamp, so that the signal lamp of that circuit in which the signal was given or the fault occurred, is switched on, and keeps burning as long as the disturbance lasts.

Now the attention signalling apparatus must be put in operation, which takes place in the following way:

As indicated above, the point 17, 17' etc. is, via the rresistance 2G and the resistance 12, connected with the connecting terminal 'of the leakage resistance 14. The voltage of the point 21 is, together with the adjusted negative prevoltage (center tap of the resistance 5), impressed upon the grid of the thyratron As 'the voltage of the point 17 is an alternating voltage, the voltagcim- 'parted to 21 by the signal circuit A will also be an alternating voltage, which, in the positive part of the cycle, decreases the adjusted negative grid voltage to such an extent 'that the thyratron breaks down. Consequently current passes from the cathode to the anode of the thyratron, in consequence of which the relay Winding 9 lis excited, and the relay closes the operating circuit of the attention signalling apparatus, which is then put in operation, so that a warning is given that the normal operating condition is disturbed.

ln order to be able to put the attention signalling apparatus out of action again, so that it is immediately ready for the next warning from another signal circuit, it must be possible that after a very'short time the negative grid voltage is automatically restored to practically its original magnitude, notwithstanding the fact that the signalled disturbance is still present. The warning of this disturbance must be continued as long as it is not eliminated` This is effected in the following way: l

Because of the fact that, during a disturbance, current passes from the line A, via the resistance `16, 2.0 and 13., to the line B, the resistance 13 with thenegative temperature coeiiicient is heated. This current is exactly so large that the effect of the negative temperature coefticient is used to such an extent (about 75%) that this resistance, which in cold condition amounts to, for example, 250 k. ohm, after this current has passed through it for about 1/2 second still amounts to i300() Q. This current is still so small that the life of the resistance 13 kis hardly influenced by it. Because the resistance 13 suddenly becomes very small, the effect of the disturbance signal on the grid is reduced to such an extent that `it has no influence any more. When button 7 is pressed, the circuit of relay is interrupted and this relay is released. Conse-quently, the current `through the thyratron is also interrupted. So the attention signalling apparatus is again ready for warning of a disturbance in another signal circuit, while the signal lamp in the signal circuit in which a disturbance is present keeps burning, until the disturbance is eliminated.

It is clear that the invention-is not restricted to the above described embodiment of the signal circuit according to the invention, but that it can be modified in numerous Ways without leaving the field of the invention. Forexample, more than one attention signalling apparatus can be provided in the relay circuit, and these apparatus can be present in various places. Instead of a thyratron, another tube with control grid can also be used and even a so-called cold cathode tube. Itis also possible to construct each signalling device, independently of the other ones, as anfop'eningor clc'sing-con- -.tac't, on the understanding Vthat .if -a closing contact-is desired, the resistance 16 is omitted, and in its placelthe closing contact 28 is provided, the connection between --line vB and vterminal 1.7, which is now. effected by the signalling device with opening conta/ct 15, being entirely omitted. ll

It is to be understood that certain changes, alterations, modifications and substitutions can be made without departing from the spirit and scope of the appended claims.

What is claimed is:

l. An electric signalling system comprising at least one attention signalling apparatus and at least one locating signalling apparatus, the attention signalling apparatus being connected in a circuit including means whereby it can be disconnected independently of said locating signalling apparatus, and is immediately ready for a new warning, said system having in the operating circuit of the attention signalling apparatus, a discharge tube, the grid of which, in the normal operating condition, has such a negative pre-voltage that it is non-conductive, and circuit means connected to said grid for applying a control voltage in case of a disturbance occurring in a circuit of one of the locating signalling apparatus, said tube thereby becoming conductive, due to said control voltage Aapplied to the grid or the tube, and a resistance means having a large negative temperature coeiiicient provided in said signal circuit, the connecting terminal of which is connected with the cathode of the discharge tube.

2. Signalling device as claimed in claim 1, characterized in that it is provided with a transformer with a 'secondary winding with center tapping, the terminals of which are, via rectiers, connected with the terminals of a resistance, the center of which is connected with the center tapping of the secondary winding, while the positive terminal of the resistance is, via a contact and a relay winding of the attention signalling apparatus, connected with the anode of a discharge tube, the cathode of which is connected with the center tapping and the grid of which is, via the grid resistance, connected with a point of this resistance which is negative with respect to this center tapping and the cathode is `connected with this center tapping and the supply line.

3. A signalling device as claimed in claim 2, characterized in Ythat one of the terminals of each signaller is connected with the side of the line which is connected with the cathode of the discharge tube, the-other terminal being connected, via a resistance, with the other side of the line and viaa signal lamp with the rst mentioned side of the line, while, a line connects the second mentioned terminal to `the cathode of the discharge tube via a resistance and said resistance with a large negative temperature coefiicient, and the grid of this discharge tube is connected, via a resistance, with the connecting terminal of said resistance with a large negative temperature coetiicient.

2l. A signalling device as claimed in claim l, characterized in that one of the terminals of each signaller is connected with the side of the line which is connected with the cathode of the discharge tube," the other terminal being connected via a resistance with the other side of the line and via a signal lamp with the iirst mentioned side of the line, while, a line connects the second mentioned terminal to the cathode of the discharge tube via a resistance and said resistance with said large negative temperature coecient, and the grid of this discharge tube Vis connected, via a resistance, with the connecting terminalrof said resistance with a large negative temperature coefiicient.

5. An electric signalling system including an attention signalling apparatus and a plurality of locating signalling apparatus, said attention signalling apparatus so connected as to be actuated by the operation of said location signalling apparatus, said system including current flowcontrol means whereby said attention signalling apparatus responds to the actuation of each locating signalling apparatus as each is energized; said system comprising an attention signalling circuit including an attention signalling device and a triode connected'to a source of power, the gr-id of said triode having impressed thereon a negative potential such as to preclude the flow of current in said attention signalling cricuit, said system further comprising a plurality of sirnilar, parallel-connected locating signalling circuits mcluding a location signalling ldevicehaving one terminal thereof connected to one line of a power source and to the cathode of said triode, jswitch 4means connected to the other terminal Alocation signalling device so connected to said terminal and the other line of 's'aid lpower sourcefso that under of 'said normal conditions both terminals of said location signalling device will be at the same potential, the secondmentioned terminal of said location signalling device being connected to the circuit of the grid of said triode whereby an alternating current is impressed on said grid when said switch means is actuated and said location signalling device is energized, which will cause current to flow in the attention signalling circuit during the positive part of the cycle, and a negative temperature coefficient resistance connected between said grid signal circuit and said cathode which, at a predetermined time af ter the actuation of said attention signalling circuit, becomes conductive so as to render ineffective said grid signal to pass current through said triode to operate said attention signalling circuit, said location signalling device being energized so long as said switch means is actuated to connect said location signalling device to said power source.

6. Signalling device as claimed in claim 5, characterized in that it is provided with a transformer with a secondary winding with center tapping, the terminals oi' which are, via rectiers, connected with the terminals of a resistance, the center of which is connected with the center tapping of the secondary winding, while the positive terminal of the resistance is, via a contact and a relay winding of the attention signalling apparatus, connected with the anode of a discharge tube, the cathode of which is connected with the center tapping and the grid of which is, via the grid resistance, connected with a point of this resistance which is negative with respect to this center tapping and the cathode is connected with this center tapping and the supply line.

7. A signalling device as claimed in claim 6, characterized in that one of the terminals of each signaller is connected with the side of the line which is connected with the cathode of the discharge tube, the other terminal being connected on the one hand via a resistance with the other side of the line and via a signal lamp with the first mentioned side of the line, while, a line connects the second mentioned terminal to the cathode of the discharge tube via a resistance and said resistance with a large negative temperature coei'licient, and the grid of this discharge tube is connected, via a resistance, with the connecting terminal of the resistance with said large negative temperature coefficient.

8. An electric signalling system including an attention signalling apparatus and a plurality of locating signalling apparatus, said attention signalling apparatus so connected as to be actuated by the operation of said locating signalling apparatus, said system including current flow control means whereby said attention signalling apparatus responds to the actuation of each locating signalling apparatus as each is energized, said system comprising an attention signalling circuit including an attention signalling device, and a triode connected to a source of power, the grid of said triode having impressed thereon a negative potential such as to preclude the flow of current in said attention signalling circuit, said system further comprising a plurality of similar, parallel-connected locating signalling circuits including a location signalling device having one terminal thereof connected to one line of a power source and to the cathode oif said triode, the second terminal thereof being connected by means of a normally closed switch to the same line of the source of power, thus maintaining the same potential at said location signalling device, said second terminal also being connected to the other line of said power source through a current limiting resistor and further connected to the grid of said triode, whereby upon opening of said normally closed switch, an alternating current signal will be impressed on said grid causing current. to flow in said attention signalling circuit during the positive part of the cycle, and a negative temperature coeicient resistance connected between said grid signal circuit and said cathode which, after a predetermined period of time become of such value of resistance as torender said grid signal ineffective to pass current through said triode to operate said attention signalling circuit, said location signalling device being energized so long as said normally closed switch remains open.

9. Signalling device as claimed in claim 8, characterized in that it is provided with a transformer with a secondary winding with center tapping, the terminals of which are, via rectiers, connected with the terminals of a resistance, the center of which is connected with the center tapping of the secondary winding, while the positive terminal of the resistance is, via a contact and a relay winding of the attention signalling apparatus, connected with the anode of a discharge tube, the cathode of which is connected with the center tapping and the grid of which is, via the grid resistance, connected with a point of this resistance which is negative with respect to this center tapping and the cathode is connected with this center tapping and the supply line.

i0. A signalling device as claimed in claim 9, characterized in that one of the terminals of each signaller is connected with the side'of the line which is connected with the cathode of the discharge tube, the other terminal being connected on the one hand via a resistance with the other side of the line and via a signal lamp with the rst mentioned side of the line, while, a line connects the second mentioned terminal to the cathode of the discharge tube via a resistance and said resistance with a large negative temperature coeicient, and the grid of this discharge tube is connected, via a resistance, with the connecting terminal of the resistance with said large negative temperature coelicient.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,127,343 Parlett Aug. 16, 1938 2,493,548 Proctor Jan. 3, 1950 2,501,793 Sperry Mar. 28, 1950 2,614,160 Foote et a1. Oct. 14, 1952

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