Patent GB-992145-A (GB)
Title: Improvements in or relating to a data system
IPC: G01B7/06
Filed: 1962-12-28
Abstract: 992, 145. Program controlled thickness measurement; record apparatus. LABORATORY FOR ELECTRONICS Inc. Dec. 28, 1962 [Dec. 29, 1961], No. 48848/62. Headings G1A and G1J. Apparatus for measuring and providing a twoco-ordinate output record of a variable characteristic of a moving material strip 11, Fig. 1 comprises a transducer 14, adapted to measure and provide an output indication of the said variable characteristic in the region of the transducer, a scanning means adapted to scan repetitively the transducer, a scanning means adapted to scan repetitively the transducer back and forth transversely across the material strip and to provide an output indication continuously of the transverse position of the transducer, a two co-ordinate strip chart pen recorder 17, the strip chart, Fig. 3, having bidirectional vertical motion Y, and the strip chart recorder having a chart input for controlling the said vertical motion, and having a scribing pen 28 at a fixed vertical position, adapted for bi-directional horizontal motion, and a pen input for controlling the horizontal position of the pen, a first signal generator circuit providing an output signal equivalent to the output signal of the transducer for a predetermined desired valve of the variable characteristic, a graduated scale member 25 attached to the strip chart recorder in a horizontal position, indicator means 26 associated with the first signal generator and the scale member and adapted to provide a visual indication on the scale member of the said predetermined value, circuit means responsive to the transducer output, the scanning means output and the first signal generator output providing for each scan an output record on the strip chart recorder, including a plot A to B of the transducer output as a function of the scanning means output, with the transducer output variations being represented as variations in the vertical directions and with the said transverse position being plotted on the horizontal co-ordinate, a second horizontal line (dotted line through E) at a vertical position representing the predetermined desired value, and a vertical line E to F at a horizontal position corresponding to the position of the indicator on the graduated scale member. The invention is described applied to the measurement of the thickness of a travelling web of material 11, by means of a radio-active source 20 and an ionization chamber detector 20. On the strip chart, Fig. 3, a horizontal line is first drawn representing a desired thickness (shown as the dotted line through E), after which the thickness profile of the web is drawn from A to B following the travel @ of the detector 20. The pen remains at B for a few seconds whilst circuit means connected to the output of the detector work out the average value of the thickness over the first completed scan. The pen then traces from C to D at a vertical position representing this average value. Point D represents on scale 25 the desirec thickness value on an expanded scale relative to the vertical scale used for the horizontal line through E. The desired thickness valve is set into the apparatus by knob 27 and indicated by pointer 26. The chart now moves so that the line D to E is drawn and then the line E to F. A new desired thickness line, F to G and G to H is now drawn, and a new profile is drawn. The measuring circuit of the arrangement is shown in Fig. 4, and is controlled by a program produced by the controlled circuit of Fig. 5. In Fig. 5, switches 51 to 58 are controlled by cams carried on the shaft of cam motor 44 whilst relay contacts such as 42g without any line across them and normally open, and those such as 61, with a line, are normally closed. In the program chart, Fig. 6 the shaded areas represent when a relay is energized on a cam switch is moved by its associated cam, or when clutch 75, Fig. 4, is engaged, or when the X to Y drive motors are energized. At time to the pen is at A and the switches &c. are as shown in Fig. 5. The scan drive unit starts to move detector 14 and source 20 across the web and immediately causes a signal to close relay contact 64 so energizing the Y drive motor 47. The scan drive unit also moves the contact of potentiometer 71, which is grounded via contact 41a. This causes the X drive motor 46 to adjust the wiper 83 of potentiometer 80, until a balance is obtained when the voltage across the motor amplifier 84, i.e. the voltage difference between the wipers of the two potentiometers 71 and 80, is zero. The motor 46 is also connected to the pen so that the pen follows the movement of the detector &c. from A to B. The output from the detector is used to move the wiper 101 of a potentiometer 100, which is connected to ground through closed contacts 43a and 42f. This causes the Y drive motor 47 to adjust the wiper of potentiometer 110, until balance is restored. The Y drive motor is connected via a clutch, which at this time is engaged, due to the energization of clutch control 45, Fig. 5, to the chart drive, to cause the chart to move vertically in response to the detector output causing the profile A to B to be drawn. When the trace A to B is completed a signal is sent to the detector circuit which then provides the average value of the thickness over the first completed scan. The Y motor moves the chart accordingly, to trace point C. Contact 64 opens five seconds after point B has been reached de-energizing the Y drive motor. At time t 1  the scan drive unit reverses its direction and sends out a signal closing contact 62, thereby energizing the cam motor 44 and commencing the cam controlled program. The said drive unit signal also opens contact 63. Switches 56 and 58 are immediately cammed down. The cam motor 44 remains energized through switch 57. The movement of switch 56 re-energizes the Y drive motor 47. Switch 51 is also cammed down, energizing relay coil 41, changing over contacts 41a, 41b and 41c with the result that the X drive motor 46 now rebalances the potentiometer 80 against the wiper of set point potentiometer 90, causing the pen to move across, drawing the average thickness line C to D. At time t 2  switch 52 is cammed up, de-energizing the X drive motor 46 and energizing relay coil 42, changing over contacts 42a ... 42g. This causes the set point potentiometer 90 to be connected across the Y balance potentiometer 110, the wiper 101 of potentiometer 100 being disconnected from ground by the opening of contact 42f. The Y drive motor therefore ad - justs the wiper of potentiometer into balance with the wiper of potentiometer 90 causing the chart to move up, resulting in the line D to E. Point E will lie on a previously drawn horizontal line shown as dotted, representing the set point in the vertical scale of the thickness profile. At time t 3  switch 53 is cammed up, de-energizing clutch control 45 causing the clutch 75 to disengage. Relay coil 43 is also energized, causing relay coil 42 to be deenergized by contact 43c opening, and causing the Y drive motor to adjust the wiper of potentiometer 110, until balance is obtained with the grounded centre scale point between resistors 105 and 106, by contact 43a opening and contact 43b closing. No movement of the shunt results however due to the clutch 75 being disengaged. De-energizing of relay coil 42 causes the potentiometer 80 to be connected across the set point potentiometer 90. No movement of the pen results however as the X drive motor is not energized. At time t 4  switch 54 is cammed up re-energizing the clutch control 45 and causing the clutch 75 to be re-engaged. No movement of the chart results however since the potentiometer 110 is already balanced. At time t 5  switch 51 is cammed up de-energizing relay coil 41 and returning contacts 41a and 41c to their normal state. The opening of contact 41c puts resistor 107 in series with resistors 105 and 106 and causes the Y drive motor 47 to rebalance the potentiometer 110. Since the clutch is now engaged this causes the chart to be driven down such that E to F is drawn. At t 6  switch 54 is cammed down causing the clutch to disengage. At t 7  switch 55 is cammed down, de-energizing relay coil 43, disconnecting the junction of resistors 105 and 106 from ground, and energizing relay coil 42, causing the set point potentiometer 90 to be connected across the potentiometer 110. Relay coil 41 is also energized causing the wiper of the set point potentiometer 90 to be grounded. The Y drive motor 47 therefore adjusts the potentiometer 110 until balance is restored with potentiometer 90. No movement of the chart results however as the clutch 75 is disengaged. At time t 8  switch 53 is cammed down causing the clutch 75 to engage. At time t 9  switch 52 is cammed down energizing the X drive motor. Since contact 42a is closed the X drive motor adjusts the wiper of potentiometer 80 until balance is reached with the wiper of position limit potentiometer 73. The pen is therefore driven to the left, drawing the line F to G. At time t 10  switch 56 is cammed up de-energizing the Y drive motor 47. At time t 11  switch 55 is cammed up de-energizing relay 41. The wiper of potentiometer 71 is now grounded and the X drive motor causes the pen to move to a random position somewhere between point G and the position corresponding to the present position of the detector 14. At t 12 , switch 57 is cammed down energizing relay coil 43 and opening contact 43c, thus de-energizing relay coil 42. Contact 42a now opens and the pen is driven to follow the detector 14 to point H. Also as the detector travels over the web to give line G to H it produces a signal, opening contact 63 and stopping cam motor 44. When point H is reached this signal ceases and the cam motor 44 is started. At time t 13  switch 57 is cammed up, de-energizing relay coil 43 and earthing the wiper of potentiometer 100 in preparation for the ne