Apparatus for integration and averaging

• US 3,906,190 A
• Filed: 06/27/1973
• Issued: 09/16/1975
• Est. Priority Date: 06/30/1972
• Status: Expired due to Term

• Current Assignee: Leon Henry Light
• Original Assignee: Leon Henry Light
• Inventors: Light, Leon Henry
• Primary Examiner(s): Cook, Daryl W.
• Assistant Examiner(s): Kilgore, Robert M.
• Application Number:
  US05/374,066
• Time in Patent Office: 811 Days
• Field of Search: 235/61.6A,61.6B,61.12C,61.11A,61.12R,61.11C 340/146.3SY,173R 200/46 178/18
• US Class Current: 708/830
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06G 7/04 Input or output devices graph readers G06K11/00; function plotters, co-ordinate plotters G06K15/22, G09G3/001
• CPC Class Codes: G06G 7/186 using an operational amplifier comprising a capacitor or a resistor in the feedback loop

Abstract

An integrator and averager for use with graphs or recorder charts is described. In use the graph is placed on a tablet and a stylus is used to follow the curve. The tablet has an upper conductive sheet and a lower layer which may be a series of parallel conductors or a condutive layer. Voltage is normally applied across the lower layer in the direction of the independent variable and sensed from the upper sheet. An increment detector causes voltage to be applied across the lower layer instead, for a predetermined interval, in the direction of the dependent layer, each time an increment of the independent variable is detected. An integrator is charged during the intervals and its output is indicative of the area under the graph. By automatically dividing the interval of the independent variable over which the graph was traced, the average value is obtained.

Claims

1. Apparatus for use in determining the integral between predetermined limits of a function from a graph of the function between the limits, including a first member in the form of a sheet of material over which, in operation, a graph of a function represented on flexible material is placed, a second member having a surface parallel and adjacent to, but not in contact with the first member, the members being of electrically conductive material and the sheet being of such material and so mounted that is able to deform temporarily and make contact with the said surface over a relatively small area when pressed towards the surface by stylus means used to follow the curve of the graph, means for applying a voltage across one of the members, and an integrating circuit coupled to the other member, the apparatus being such that if the axis of the independent variable of the graph is placed in a predetermined position, the two members can be so pressed into contact in following the curve that sample signals representing the dependent variable of the graph pass to the integrating circuit, and the said otheR member being so coupled to the integrating circuit that sample signals pass to the integrating circuit at increments of the independent variable which are equal to one another.

2. Apparatus according to claim 1 wherein the said one member is made of material which is sufficiently resistive to provide a convenient potential gradient in that member to allow the said sample signals in the form of currents to be distinguished clearly between values of the dependent variable of different magnitudes.

3. Apparatus according to claim 1 wherein the said one member is made of carbon loaded plastics material, or glass cloth covered with silicone rubber.

4. Apparatus according to claim 1 wherein the said one member has a rectangular surface with electrodes of high conductivity material along opposite edges, the means for applying voltage being coupled to the electrodes with the result that in operation equipotentials exist in the said one member substantially parallel to the electrodes.

5. Apparatus according to claim 1 wherein both the first and second members are of continuous resistive material.

6. Apparatus according to claim 5 wherein the said other member is chosen from the group comprising Teledeltos paper, and a palladium-silver cement.

7. Apparatus according to claim 5, including switching means for coupling the means for applying voltage to the said other member except when caused by a control signal to couple the means for applying voltage to the said one member, voltage being applied, in operation, in directions mutually at right angles in the two members, an increment detector for providing a control signal for the switching means each time the signal applied to the increment detector changes by more than a first predetermined amount, the switching means also coupling the increment detector to the said one member when voltage is applied to said other member and coupling the integrating means to the said other member only when voltage is applied to the said one member.

8. Apparatus according to claim 1 including means for dividing the output signal of the integrating means by the interval of the independent variable which is tranversed by the stylus.

9. Apparatus according to claim 1, including means for preventing the generation of a control signal and for providing an alarm when the signal applied to the increment detector changes by more than a second predetermined amount of larger magnitude than the first predetermined amount.

10. Apparatus according to claim 9 wherein the increment detector includes a comparator with one input coupled to the switching means and another input coupled to a further integrating means, and means for passing an increment to the further integrating means each time the comparator indicates that its input signals have become equal.

11. Apparatus according to claim 10 including a division circuit for dividing the output of the first mentioned integrating means by that of the further integrating means to provide the average value of the graph followed with the stylus.

12. Apparatus according to claim 10 wherein the first mentioned integrating means is coupled to indicating means for indicating the value of the output signal thereof, the indicating means being of a type in which the indication given is proportional to a reference signal, the indicating means being coupled to receive a reference signal which is dependent on the output of the further integrator.

13. Apparatus for use in determining the integral between predetermined limits of a function from a graph of the function between the limits, including a first member in the form of a sheet of material over which, in operation, a graph of a function represented on flexible material is placed, a second member parallel and adjacent to, but not in contact with a surface of the second member, the members being of electrically conductive material and the sheet being of such material and/or so mounted that it is able to deform temporarily and make contact with the said surface over a relatively small area when pressed towards the surface by stylus means used to follow the curve of the graph, means for applying a voltage across one of the members, and an integrating circuit coupled to the other member, the apparatus being such that if the axis of the independent variable of the graph is placed in a predetermined position, the two members can be so pressed into contact in following the curve that sample signals representing the dependent variable of the graph pass to the integrating circuit, and the said other member being so constructed and so coupled to the integrating circuit that sample signals pass to the integrating circuit at increments of the independent variable which are equal to one another.

14. Apparatus according to claim 13 wherein the said one member is the first member, the second member comprises a plurality of parallel spaced conductors having surfaces which together form the said surface of the second member, the conductors being connected together and coupled to the integrating means.

15. Apparatus according to claim 14 including a gate circuit coupled between the conductors and the integrating means, and timing means for opening the gate circuit for a predetermined interval each time a conductor is first contacted by the first member.

16. Apparatus according to claim 15 including averaging means comprising a manually-adjustable reference signal source which can be set to provide a reference signal representative of the interval of the independent variable which is traversed by the stylus, and wherein the timing means is adapted to control the duration of the predetermined interval in accordance with the reference signal.

17. Apparatus according to claim 13 wherein the second member comprises at least three groups of parallel spaced conductors having surfaces which together form the said surface of the second member, the conductors of the groups being coupled to the integrating means and so interleaved that in using the stylus to trace out a curve with the independent variable continually increasing, or continually decreasing, unless remaining constant, a sequence of contacting the conductors with the first member takes place in which a conductor from each other group is contacted before a conductor in the same group as the conductor originally contacted is contacted, and so on cyclically, and wherein the apparatus also includes logic circuits for providing an alarm if the said sequence is departed from.

18. Apparatus according to claim 17 including gate circuits each individually coupled between one of the groups of conductors particular thereto and the integrating means, and timing means for opening a gate circuit for a predetermined interval each time a conductor in the group coupled to that gate circuit is first contacted by the first member.

19. Apparatus according to claim 13 wherein the second member is a rigid resistive sheet having four rows of discrete conducting areas, the rows being arranged to form a rectangle and the means for applying voltage includes four switching means, one associated with, and particular to, each row, each switching means being adapted, on receipt of a switching signal, to connect at least some of the discrete areas of the row associated therewith, the switching means associated with opposite rows being adapted to operate in pairs to apply voltage between connected discrete areas in one pair of opposite rows alternately with connected discrete areas in the other pair of opposite rows.

20. Apparatus according to claim 19 including an increment detector for providing a switching signal for the switching means each time the signal applied to the increment detector changes by a predetermined amount, the switching means being adapted to couple the increment detector to the said other member while voltage is applied between discrete areas in one pair of opposite rows and to apply voltage between discrete areas in the other pair of opposite Rows and to couple the integrating circuit to the said other member when the increment detector provides a switching signal.

21. Apparatus according to claim 13, including means for dividing the output signal of the integrating means by the interval of the independent variable which is traversed by the stylus.