US3058111A - Potentiometric recorders - Google Patents

Description

1962 E. DUNCOMBE ETAL 3,058,111

POTENTIOMETRIC RECORDERS Original Filed March 9. 1956 4 Sheets-Sheet 2 I06 90 IOI 95 98 97 96 89 I02 E. DUNCOMBE ETAL 3,058,111 POTENTIOMETRIC RECORDERS 4 Sheets-Sheet 3 Oct. 9, 1962 Original Filed March 9. 1956 FIG. 3 FIG. 4

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United States Fatent 3,058,111 POTENTIOMETRIC RECORDERS Edward Duncornbe, Great Saughall, Chester, and Kenneth Walter Paget, Brornhorough, England, assignors to United Kingdom Atomic Energy Authority, London, England Continuation of application Ser. No. 570,585, Mar. 9, 1956. This application Oct. 28, 1960, Ser. No. 65,763 Claims priority, application Great Britain Mar. 10, 1955 2 Claims. (Cl. 34634) This invention relates to potentiometric recorders and it provides a potentiometric recorder capable of recording quantities of similar magnitude measured at a large number of points over a prolonged period While maintaining the Whole record visible in the window of the recorder.

According to the present invention a potentiometric recorder of the kind having a linearly movable chart comprises y pens spaced apart along the direction of movement of the chart and capable of moving together in the direction transverse to the movement of the chart, means for moving the pens to x transverse stations with zero signal input so that xy areas are available on the chart to record quantities at xy points by selection of the appropriate pen and the appropriate station. This application for patent is a continuation of patent application Serial No. 570,585, filed March 9, 1956, now abandoned.

A potentiometric recorder according to the invention will now be described with reference to the accompanying drawings wherein:

FIGURE 1 is a plan view,

FEGURE 2 is a section on the line IIII of FIGURE 1,

FIGURE 3 is an end elevation in the direction of the arrow III of FIGURE 1,

' FIGURE 3a is a diagrammatic sectional elevation of a detail of FIGURE 3,

FIGURE 4 is an end elevation in the direction of the arrow IV of FIGURE 1,

FIGURE 5 is a sectional view of a pen holder arm,

FIGURE 5A is a sectional view of a pen.

FIGURE 6 is a sectional view of an electromagnetic device for operating the pens in the holder of FIGURE 5,

FIGURE 7 is a front elevation,

FIGURE 8 is a circuit diagram.

Referring to FIGURES 1 and 2, the frame 10 of a conventional potentiometric recorder is adapted to support nine parallel bus-bars 11, and a bus-bar 12, a divided contact bar 13 and a contact plate 14. The carriage of the recorder is modified by the addition of a bridge piece 15 which carries a pen holder arm 16, sliding contacts 17, 18, nine sliding contacts 19 and associated wiring which comprises a 9-wire cable 24 a cable clip 21 and a terminal block 22. The chart drum 36 of the recorder is modified by the addition of a band brake having a brake wheel 23. (The brake is described in detail with reference to FIGURE 3 below.)

The details of the above modifications are now referred to together with reference to the conventional items. The bus-bars 11 are supported in an insulator bed 24 held to the frame 16 by screws 25 and are clamped in position with clamping bars 26 and screws 27. The bus-bar 12 and contact bar 13 are held in V-grooves 28 formed in an insulator block 29 supported on angle brackets 36 held to the frame 19 by screws 31. The bar 12 and the segments of bar 13 are held to the block 29 by studs 32 in the bars which penetrate the block 29 and are provided with nuts 33. The bar 13 consists of siX rods 34 which are spaced apart and insulated from one another by insulator spacers 35. The underside of the 'block 29 carries terminals 37 to which are connected wires from the bar 12 and the rods 34. The traversing carriage of the recorder comprises an endless band 38 passing over pulleys 39 (one or" which is driven to move the carriage to a point fine of balance). An anchor block 40 is secured to the lower part of the band 38 by nuts and bolts 42. A plate 41 is secured by screws 44 to the block 40 and a 'bar 43 is secured to the plate 41 by screws 44. The bar 43 moves on runners 63 and rails 64. The bridge piece 15 is carried from the bar 43 and held by screws 45. The bar 43 also carries two pillar-s 46, 47 held by screws 48, 49 respectively.

The pillars 46, 47 carry the sliding contacts 19 and the pillar 46 has a hole 50 through which passes a spiral potentiometer Wire 51 swept by a Wiper 52 attached to, but insulated from the pillar 46. A bus-bar 53 supported in a holder 54 is swept by a wiper 55 also attached to the pillar 46.

Supported from the bridge piece 15 there is a forked member 56 held by screws 57. The member 56 is fitted with a pin 58 having a lock-nut 59. The pen holder arm 16 pivots on the pin 58 and rests against a linearly moving chart 6% which runs over the ground surface of contact plate 14. The plate 14 is supported by three countersunk screws 61 fitted into screwed spacers 62. The spacer 62 can be screwed in or out from the frame 111 so as to set the correct plane to the surface of contact plate 14. The chart drum 36 frictionally engages a shaft 65 which is driven via gear wheels 66, 67; the gear wheel 67 being driven from a shaft 68.

In FIGURE 3 a brake band 69 is shown passing over the brake wheel 23. The band 69 is tensioned by a spring 70 and is anchored at one end by a screw 71 and nut 72 cooperating with a bracket 73 fixed to the frame 10. At the other end the band is anchored by screws 74 passing through an end lip '75 and the band 69 into a bracket 76 held to the frame 11 by screws 77. The frictional torque given to the shaft 65 by reason of the brake band 69 is arranged to be substantially greater than that given by the frictional engagement of the drum 36 on the shaft so that the chart can be advanced by hand Without introducing slack in the drive to the shaft 65 at gear wheels 66, 67. At the lower end of FIGURE 3 (and diagrammatically in FIGURE 3a) a charrt-wind spool shaft 78 is shown having a spur wheel 79 connected with a knurled knob 36. The Wheel 79 and knob 80 can rotate on the shaft within limits allowed by a spring 81 which is coupled to the shaft at one end and the wheel 79 at the other. The chart-wind drum 82 is shown. The knob 80 can be rotated in advance of the shaft 78 so as to spring load the shaft and the drum 82 attached to the shaft thereby keeping the chart 60 tensioned. Associated with the gear wheel 79 there is a wheel 148 in mesh with wheel 79. A pawl 149 and spring 150 function with the teeth of wheel 148 so that the manually set tension in the spring 81 is prevented from escape by the pawl 149.

FIGURE 4 shows further detail of the drive to the chart drum 36. The shaft 68 is supported in bushes 83, 84 in brackets 85, 86. The shaft has a worm wheel 87 engaging with a worm 88 of a motor driven at constant speed through substantial reduction gearing.

The pen holder arm of FIGURE 5 comprises a top block 89 and a bottom block 90 which are fixed to a channel section member 91. Between the blocks 89 and 90 there is a push rod 92 which moves in a top bush 93 and passes through eight bell cranks 94 of insulating material pivoted on pins 95. Each bell crank carries an electrode pen 96 (see also FIGURE 5A) which has an electrical connection 97 which leads back via a connector 98 and wire 99 along the inner wall of member 91 to cable 20. Between the bell cranks 94 and around the push rod 92 there is a series of springs 100. A miniature size ball race 161 is mounted in the bottom block 90. The top block 89 is drilled to provide a hole 102 to fit about the pin 58. The bottom block 90 carries a slotted extension piece 106 provided with a hole 107,

which accommodates a pin about which a lever can pivot to operate push rod 92. In FIGURE 5A, the construction of the electrode pens 96, which make a mark by electrical discharge through the chart 60 to the contact plate 14, is shown. A bush 103 carries a tungsten wire 104. The wire is made rigid in the bush by staking the flange end of the bush. A bead 105 of silver solder is provided at the end of the wire 104-.

In FIGURE 6 an electromagnet 108 has a coil 109 and a copper plated mild steel slug 110 movable in a brass slug tube 115. The tube 115 has a mild steel end piece 116 and carries a pole piece 112. The coil has a casing 117 held in position by a retaining nut 118 which screws into an end piece 111 of the slug tube 115. The electromagnet 108 is carried on a base plate 119 by a bracket 120. The slug 110 has extension pieces 113 and 114. The piece 114 terminates in a nut and washer 121, 124 and retains a spring 122. The piece 113 is drilled to accommodate the end of a coupling spring 123. The base plate has two brackets 125 which support a lifting link 126 which can pivot about a pin 127. One arm of the link 126 is connected with the spring 123 and the arm is fitted with two rods 128 on which rests a follower link 129 which is provided with a hole 130 so that it can be mounted to hinge about a pin in the hole 107 of FIGURE 5 to operate the push rod 92. The inclined face 131 of the link 129 applies a small force to move the push rod in a direction to keep the pens 96 in arm 16 pressed to the chart 60. The roller 101 (FIGURE 5) gives correct spacing.

In FIGURE 7, the assembly of the electromagnet 108 and its associated parts are shown together with a typical 48 point chart presentation. The rods 128 are fitted with a follower link 132 which pivots on brackets 133 in a similar manner to that of the lifting link 126. The construction of the bridge member is shown. This consists of two I-section members 134 joined with two plates 135. The chart 60 shows forty-eight records 136 which represent the deviation of forty-eight voltages each sampled every thirty minutes over a twenty-four hour period. A balancing motor 137, used for moving the band 38, bridge member 15 and pen-holder arm 16, is shown.

In FIGURE 8, a fifty outlet uniselector has three banks 151, 152, 153. The contacts of bank 151 are connected in common every 6th contact thus presenting eight groups of six (H1 to 6), one contact in each group being swept by the wiper arm 138 in turn as it moves together with arms 139, 140 under timed impulses fed to the driving motor of the uniselector. The contacts of bank 152 are connected so that the first six are connected in common and then the next six and so on. The two spare contacts on bank 152 are connected to earth. The common connections from bank 152 are each taken to one of the eight pens 96 (FIGURE 5) via bus-bars 11 (FIGURES l and 2,), wipers 19 (FIGURE 2), and cable (FIG- URES 1 and 2). The pens 96 are indicated by the references P1 to 8. The common connections from bank 151 are respectively taken to points S1 to S6 in a chain of resistances 142 between fixed resistances 143a and 144. The slide wire 51 lies between fixed resistances 143b, 1430, thus forming a bridge B having variable ratio arms governed by which of the points S1 to S6 is selected for an input. The bridge B is self balancing by a standard amplifier and servo control mechanism 159 to the wiper arm 52 from terminals 155 of the forty-eight voltage points. The other terminals, namely terminals 156, of the forty-eight voltage points are coupled to the bridge B one at a time via a contact on bank 153, wiper arm 140 and wiper arm 138 to the appropriate one of the points S1 to S6.

With no signal at any of the voltage points the movement of the arm 138 causes the ratio of the arm of the bridge to change cyclically so that the wiper 52 balances cyclically at six points along the length of the slide wire 51. These six points are the six transverse stations of .1 zero signal input. 'Where a signal exists at any of the forty-eight voltage points the signal causes a further movement of the wiper 52 from the appropriate zero signal input position, the movement being proportional to the amplitude of the signal.

To provide a potential source to fire the pens 96 a condenser 146 is connected via a change-over switch 145 first to a battery 147 with limiting resistor 157 and then to wiper arm 139 via limiting resistor 158. A record is made on the chart 60 every thirty seconds. For this to be achieved the uniselector driving motor, the electromagnet 108 and the change-over switch 145 are operated in the following cycle by cams and contacts driven from a constant speed electric motor. At 0.00 second the uniselector driving motor is operated so that wiper arm 139 is connected with R1, wiper arm is connected with terminal 156/1 and wiper 138 is connected with H1 and point S1. The recorder then balances at a position beyond station 1 representative of the signal derived from terminal 156/ 1. At 29.00 seconds the electromagnet 108 is operated to bring the pens in contact with the chart 60. At 29.50 seconds the change-over switch operates to discharge condenser 146 through P1 thus making a record on the chart 60 at station 1, pen 1. At 29.75 seconds the electromagnet 108 releases and the contact 145 is restored to recharge condenser 146 from the battery 147. At 30.00 seconds the operations of recording at station 1, pen 1 are completed and the uniselector driving magnet is re-energised which leaves Wiper 139 made to P1 but via the next contact of bank 152, makes wiper 140 reach terminal 156/2, and wiper 138 to H2 and 82 so that the wiper 52 moves to station 2 in readiness to record with pen 1 the potential between the second set of terminals 155, 156 and so on through the six stations when station 1 is reverted to but with pen 2 for the seventh set of terminals 155, 156. If it is assumed that the record at the 48 stations is required for a 24 hour period and the uniselector moves one step every 30 seconds, then for about 14" length of chart exposed in the window of the recorder the chart movement and hence the length of a record for any point, such as 156/1, is about 1.5 and the chart speed is 0.060 per hour. The forty-eight records are each made up of 57 marks each spaced by about 0.027. At the end of the twenty-four hour period the chart is advanced fourteen inches and the next days recording commenced.

The bus-bar 12 together with divided contact bar 13 provide means whereby the position of the arm 16 can be remotely monitored and its cyclic movement checked, and it can also be used to operate a high level alarm should the signal input be so excessive as to carry the contact 18 on the adjacent segment of contact bar 13.

We claim:

1. In a potentiometric recorder having input terminals, a recording chart movable smoothly with time over a member defining a flat surface on the chart between a chart storage drum and a chart take-up drum and a balancing member movable transversely to the chart to take up static positions according to the balancing of a potentiometer against input signals, the features of an arm attached to said balancing member extending lengthwise along the fiat surface of the chart, a series of y electrically fired recording pens spaced apart along said arm, and three intercoupled selector switch means each having a selector and multiple contacts and means ganging the selectors to move together, the first switch means having an electrical connection from its selector to the input terminals of the recorder and connections from its multiple contacts to signal input points, the second switch means having an electrical connection from its selector in series with the selector of the first switch means and connections from its multiple contacts to x fixed voltage points and the third switch means having a connection from its selector to a source of electrical energy for firing said pens and connection from its multiple contacts to said pens.

2. A potentiometric recorder comprising a chart, means causing said chart to move linearly with time, a carriage movable in a direction transverse to said chart, means causing said carriage to move in a series of x pairs of alternating phases, the first phase of one of said pairs being a transverse movement dependent upon a signal of predetermined amplitude fed to the recorder and the second phase of said one pair being a further transverse movement dependent upon a signal to be recorded, each pair of phases in the series taking the carriage further across the chart until the x pairs of phases are completed, an arm movable with said carriage and extending in the direction of movement of said chart, y pens for marking said chart spaced apart along said arm, means for causing xy signals to be recorded to be fed cyclically t0 the recorder and switch means providing that the first of said xy signals causes the first of the y pens to mark the chart when the carriage has moved through a second phase of the first of the x pairs of alternating phases in a first series, that the second of said xy signals causes the first of the y pens to mark the chart when the carriage has moved through the second phase of the second of the x pairs of alternating phases in said first series and so on until the xth of said xy signals causes the first of the y pens to mark the chart when the carriage has moved through the second phase of the xth of the said at pairs of alternating phases in said first series when the x+1th of said xy signals causes the second of the y pens to mark the chart when the carriage has moved through the second phase of the first of the as pairs of alternating phases in a second series and so on until the xyth of said xy signals causes the yth of said y pens to mark the chart when the carriage has moved through the second phase of the xth of the x pairs of alternating phases of a yth series.

References Cited in the file of this patent UNITED STATES PATENTS 2,614,900 Clarke et a1. Oct. 21, 1952 2,625,458 Ruhland Ian. 13, 1953 2,639,964 Keinath May 26. 1953

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