US2620383A - Signaling system - Google Patents

Description

Dec. 2, 1952 G. GLINSKI SIGNALING SYSTEM Filed Sept. 25, 1948 500 bit OEMQ M/VENTOR G. GL/NSK/ By e. cw a ATTORNEY Patented Dec. 2, 1952 SIGNALING SYSTEM George Glinski, Belleville, Ontario, Canada, as-

signor, by mesne assignments, to Northern Electric Company, Limited, Montreal, Quebec, Canada, a corporation of Canada Application September 23, 1948, Serial N 0. 50,737

4 Claims. 1 This invention relates to a detection device for use in the detection of the displacement of a magnetizable body in a particular predetermined direction.

An object of the invention is the improvement of detection devices employed in detecting the improved relay provides a signal if the move- I ment is in a particular predetermined direction.

Such a device may be used to advantage, for

instance, in controls for vehicular traflic where directional discrimination is essential.

There are presently known in the art, particularly in the vehicular trafiic control art, a number of devices which perform the same fundamental function as does the relay of the present invention. However, so far as is known, there is no relay which is operated in response to displacement of a vehicle and which affords directional discrimination in a vehicular trafiic control which is not subject to failure under one or another operating condition. In certain of these devices, for instance, the directional discrimination aiiorded by the device depends on the traverse of two magnetic detecting coils which are so spaced in the roadway that they are activated in sequence by a moving vehicle. Directional discrimination is afforded by the activation of the detecting devices in sequence in a particular order. For instance, for one direction of travel detecting device I is first activated fol lowed by the activation of detection device 2. The relay may be arranged to provide a ositive indication for this particular mode of operation Whereas traverse in the opposite direction resulting in the actuation first of detector 2 followed by the actuation of detector 1 would provide no indication In certain of the devices designed for operation on this principle a chain of operation is initiated say by the activation first of detector I. In order to complete the conditions under which the relay provides a positive indication, it is necessary that detector 2 be activated within a particular interval after detector 1 operates. The rate of traverse of vehicles varies Widely from say a fraction of a mile per hour for a heavily loaded truck to speeds which may in some cases exceed seventy or eighty or more miles an hour. The requirements imposed on the presently known relays for such conditions are very severe, more severe than can be met. Relays operating in conjunction with sequentially traversed detectors are set so as to be operative over a certain average range of speeds and are therefore limited in their application to service where such operation will sufice.

Each other known form of magnetic vehicular control which is operative in response to movement of a vehicle and which affords directional discrimination is subject to some limitation in its operation which can be revealed by study of the proposed device and for this reason they have not been widely applied for this purpose although magnetic detectors are widely used in applications where directional discrimination is not required.

The present relay does not depend upon the sequential traverse of a number of detecting devices. A single detecting device, which may for instance be a single coil wound on a magnetizable core, disposed in such manner that the flux traversing the core due to the earths magnetic field is changed so that a voltage wave is generated in response to the displacement of the magnetizable body, such as the movement of a motor vehicle in the vicinity of the detecting device, is all that is necessary to control the present relay.

It is well known that the pattern of the generated voltage waves in a detecting coil is different for opposite directions of displacement of the magnetizable body. In particular it has been found that if, for instance, the displacement of the body ina first direction generates a voltage wave, the first pulse of which is positive, displacement in the opposite direction will generate a voltage wave the first portion of which is negative. The patterns of the generated voltage waves vary depending upon the shape and mass of the displaced magnetizable body, the direction and intensity of the earths magnetic field at the particular point, the characteristics of the detecting coil and the disposition of the detecting coil with respect to the direction of displacement. Since, however, for all conditions the first pulse of the generated voltage wave is positive for one direction of displacement and negative for the opposite direction, advantage may be taken of this characteristic to afford discrimination if the cooperating relay is made responsive to the first pulse of a wave which is, for instance, positive and non-responsive toa first pulse which is negative and if it can be arranged so that it is unaffected by subsequent pulses in the wave. This can be performed for instance by means of an electron device which discriminates between the positive and negative first pulses. However, the pattern of the voltage wave which is produced under certain circumstances may be quite protracted and contain as many as four or five or more positive and negative peaks for a single traverse or displacement in one direction. Thereis not presently available in the: art' an electronic relay which will respond to a first pulseof a particular polarity and remain unaiiected bythe subsequent variations in an inordinately irregular wave of the longest required duration. The relay of the present invention meets this re.- quirement.

The invention may be understood from the following description when read with reference-to theassociated drawing which discloses a. preferred embodiment in which the invention may beeincorporated. It is tobe understood, however, that the invention is not limited to the particular embodiment described hereinbut may beincorporated in other embodiments which will readily suggest themselves to those skilled. in the art.-

In the drawings,

Fig- 1 shows the relay of the present invention; and

Figs. 2 and 3 show graphs of voltage waves impressed. on the relay- I I Refer now to Fig. 2 which shows two voltage waves A: and B which are. generated by the dis-- placementof a magnetizable body withreference to-adetecting device consisting of. a current con.- ducting coill wound on: a magneticv core, which deviceis located inclose proximity to a. displaceable magnetic body. The body, whichmay for. instance be a bar of iron passing over the detecting device, generates a train of three pulses. as shown in Fig. 2'v for each traverse. The train for one. directionv of traverse is. different from the train for the opposite direction of 'traverse. For one direction, as shown by thecurve designated A, in Fig; 2, the train consists of a. large positive pulse separating two small negative pulses; For the opposite direction, as shown by'the curve designated B in Fig; 2, the train is" the same but thepulses' are reversed in polarity with respect to the pulses of curve A.

Attention is particularly directed to the fact that' the first portion of pulse A isnegative whereas the first portion of pulse B is" positive. This opposite polarity of the first portion of a" voltage wave is characteristic of all voltage. waves generated; in detection coils in response to opposite directions of displacement of magnetic materialwith respect to the coil.

Fig; 3" shows two voltage wavesA andB gen-- erated' in a detection coil due to the'traverse of the coil" by a moving motorvehicle. for traversein one direction. Curve B for traverse in the" opposite direction. The waves are irregular and one is-only approximately the inverse of the other, but the first pulse of- A is positive while the first pulse of- B is negative. It

has been found that for a particular location of the coil and for all vehicles moving in a particular' direction the polarity of the first pulse is always uniform and it is always uniform and op posite for the opposite direction of travel..

Attention is particularly called to theirregu-- Curve A is or right.

larity of the wave pattern of voltage wave A and of voltage wave B in Fig. 3. Each of these waves has several positive and negative peaks. If a relay is to be designed to respond to the first portion of a wave, which portion is of a particular polarity, in order to be effective it must be arrangedso: that it. is unaffected by the succeeding pulses of. the wave. The. relay of the present invention is so arranged. The manner in which this is achieved will now be described.

Refer now to Fig. 1. Fig. 1 may be considered to be divided into four portions, namely a detecting coil,.'shown atthe upper left in Fig. 1, in which the voltage wave patterns such as those shownzin Figs. 2 and 3 are generated, an ampli- 'fier' shown in the middle of Fig. 1, a pulse discriminating relay arrangement shown at the upper right, and a power supply shown at the low- Terminals l and 2 are the input terminals to the amplifier. Terminals 3 and 6 are the output terminals of'therelay arrangement and terminals 5. and 6- are the alternating current supplyterminals. An alternating. potentialv is supplied from terminals 5, 6 to the primary of transformer TF2. The plate voltage for. the amplifier is supplied through rectifier V'I't and the voltage for the relay from rectifier V'IT. The cathode heater supply is furnished from the bottom right-hand secondary coil to all'tubes.v

The detecting coil is preferably disposedin such manner that the moving magnetizable body, such as a moving vehicle, traverses the coil and the differencesv between the distinguishable. first portions. of the voltage waves are most pronounced; The terminals of the coil" are connected't'o' the. input'terminal's I, 2of' an ampli'fi'en which may, for instance, be a three-stage ampliing their respective half sections VTI, I and VTI', 2, VII, I" and VTZ, '2, W34. l and W312. arranged in push-pull relation. .The stages-may have resistancev capacitance coupling. Although a three-stage push-pull resistance capacitance coupled amplifier is illustrated, the invention maybe practiced with amplifiersof other types so long as the" output of the amplifier, in response to the voltage wavc generated inthe coil I; is. adequate to: control the pulse discriminatingzrelay arrangement of the present invention connected to the amplifier output through the double pole double throw switch and the transformer TRI. The double pole double throw switch is arranged to control the direction of the amplifier output pulses applied to transformer TRI so that the polarity of the pulse applied to the pulse discriminating relay arrangementwi-ll operate it for any chosen direction of traverseand' will not operate it for the opposite directionof traverse;

The pulse discriminating device ina preferred embodiment comprises essentially the duodiode shown in Fig. 1 as VT5, l and VT5, 2, the duotriode VTB, and two magnetic relays EL! and RLZ together with a time control circuit for-each section of duo-tr'iodeVTt, which controls the-op-- eration of relays RBI and RLZ, comprising capacitance CIB and resistance RZI- for relay- RLI, and capacitance 01-6 and resistance R23 for relay RLZ'.

Normally when no voltage wave is being generated'in the detecting coil and no pulses-are impressed therefore through transformer TRI, both.

sections VT-5, 1 and VTE', 2 of the duodiode are inactivated. For this condition the right-hand" section of duo-triode VT, 6 is activated. The left-hand section of duo-triode VTB, due to the connection of cathode resistor R22, is inactivated. Relay RLZ in the plate circuit of the right-hand section of VT6 is therefore operated. The relay RLI in the plate circuit of the left-hand section of VTB is normally released and its two pairs of contacts 'I and 8, 9 and I0, respectively, are normally open. When relay RL2 is operated both armatures II and I 4 are raised, armature I I disengages from contact I2 and armature I4 engages with contact I3 so that contacts II and [2 are open and contacts I3 and I4 are closed. For this condition the circuit to the indicator terminals 3, 4, which includes contacts 9 and I0, I3 and I4, is open since contacts 9 and II] are open.

It will be assumed that the first pulse as it appears on the secondary of transformer TRI is negative. In response to this, section VT5, 2 will conduct, whereas section VT5, I will not conduct.

When duo diode section VT5, 2 conducts, the potential of the right-hand grid of duo triode VT B' is made more negative with respect to its cathode. This inactivates the right-hand section of VTG, in turn releasing relay RL2, thereby closing contacts II and I2, and opening contacts I3 and I4. The open condition of the indicator circuit through terminals 3 and 4 will be insured for this condition as contacts I3 and I4 will be open in addition to contacts 9 and I0, which of course remain open.

The closing of contacts I I and I2 when relay RL2 releases short circuits the left-hand grid cathode circuit of due triode VTB to prevent the activation of the left-hand section of VTB in response to subsequent positive pulses in the voltage wave. This circuit remains short circuited as long as relay RLZ remains released. The time constant of the bias circuit comprising capacitance CH5 and resistance R23 is such that the right-hand section of duo-triode VTB remains non-conducting for an interval longer than the duration of the incoming train of pulses. It is for this reason that subsequent positive pulses cannot operate relay RLI since the grid cathode circuit of the left-hand section of duo diode VTG remains short-circuited throughout this interval. Further negative pulses will simply insure that relay RL2 remains released. At the end of the measured interval the negative bias will be re- 1 moved from the grid of the right-hand section of duo triode VT6. Relay RL2 will reoperate closing contacts I3 and I4, opening contacts II and I2 and removing the short circuit from the grid cathode circuit of the left-hand section of VTG.

It will now be assumed that the first pulse is positive. In response to this, section VT5, I will conduct. Section VT5, 2 will not conduct. When section VT5, I conducts the left-hand grid of duo triode VTB will be made more positive with respect to its cathode, activating the left-hand section and operating relay RLI which closes both of its pairs of contacts I and 8, 9 and ID. The closing of contacts I and 8 short-circuits the grid cathode circuit of the right-hand section of duo triode VT6 so that it will remain unaffected by subsequent negative pulses in the Voltage wave presently being received. The closing of contacts 9 and I0 closes the circuit to the indicator terminals since now both pairs of contacts 9 and I0, I3 and I4 are closed simultaneously. The closing of the circuit through the indicator terminals 3, 4 wil1 control the indicator, not shown, so as to in dicate the condition.

In a preferred embodiment of the invention, the

magnitudes of the resistances, capacitances and volume control and th codes of tubes corresponding to the designations shown in Fig. 1, which afford satisfactory operation, are as follows:

Resistors Ohms RI 5,000 R2 200,000 R3 5,000,000 R4 400,000 R5 1,200 R6 400,000 R'I 10,000,000 R8 5,000,000 R9 1,200 R I 0 5,000,000 RII 200,000 RIZ 200,000 RI3 200,000 RH 6,000,000 RI5 5,000,000 RIG 5,000,000 f RI! 15,000 RI 8 400 RIS 15,000 R20 10,000 R2 I 1,000,000 R22 1,500 (critical) R23 1,000,000 R24 15,000 Capacitors Microfarads CI 2 C2 5 C3 4 C4 .002 C5 .2 C6 2 C1 5 C8 5 C9 4 CH] 2 CH 2 CI2 5 CI3 5 CI4 4 CI 5 l CIB 1 CI! 20 Volume control Ohms PI 150,000 Tubes (Radio Corporation of America, Code) VTI BSNI VTZ BSN'I VT3 BSNI VT4 SSNI VT5 8H6 VTS GSNI VT! 5Y3 What is claimed is:

1. A trafiic indicator control for regulating vehicular motor traflic, said control comprising a detecting coil, and an amplifier, said coil connected through said amplifier to a first and a second unidirectional conducting element, said elements oppositely poled, said elements connected in parallel across the output circuit of said amplifier, said coil and amplifier responsive to the passage of a magnetizable material past said coil 7 in a first direction and in a second direction, oppesite'irom-said first direction, to make said first and said second element selectively'conducting ata first and-a second time, respectively, a first and a second space discharge device each having an input circuit and an output circuit, a first and a second parallel connected resistance and condenser timing circuit connected individually in series with said first and said second unidirectional conducting elements respectively, said input circuits of said first. and said second space discharge device being connected individually across said first and said second timing circuit respectively, a first and a second magnetic relay, an in-- dividual winding on each of said relays connected in" said'output circuit of said first and said second space 'discharge device respectively, a first control circuit, for said second space discharge de-' vice-responsive to said first relay, connected to said input circuit of said second space discharge device, a second control circuit, for said first spacedischarge device, responsive to said second relay connected to said input circuit of said first space discharge device, said control circuits for preventing pulses of a signal train following thefirstpulse from afiecting its connected space discharge, and a circuit path cooperably controlledby said first and second relays.

V Atrafilc indicator control in accordance with claim 1 having a switch connected :betweemsaida coil and: said unidirectional conducting elements to reverserthe polarity of pulses applied to said elements;

3. A trafiic indicator control in accordance with claim 1 mcludingmeans fcr'maki'ng said first space discharge device normally conducting and means for making said second space dis charge device normallynon-conducting.

'4'. A trafiic indicator control in accordance withv claim 1 including a resistor. connecteddi rectly in-serie's with a cathode in "said second-space discharge device.

GEORGE GLI'NS-KI.

REFERENCES CITED The following references are-of record in the file of this patent:

UNITED STATES PATENTS Electronics Code Translator, by Babcock, in

Electronics, June 1946, pages 120-122.-

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