Interactive graphic system

• US 3,936,712 A
• Filed: 07/09/1973
• Issued: 02/03/1976
• Est. Priority Date: 04/20/1973
• Status: Expired due to Term

• Current Assignee: Gerber Systems Corp (Barco NV)
• Original Assignee: The Gerber Scientific Instrument Company
• Inventors: Logan, David J., Rich, Leonard G., Gerber, Heinz Joseph
• Primary Examiner(s): Dobeck, B.
• Application Number:
  US05/377,769
• Time in Patent Office: 939 Days
• Field of Search: 318/568, 318/576, 318/628, 318/577
• US Class Current: 318/568.1
• CPC Class Codes: B43L 13/022 automatic apparatus for recording measured values G01D; control systems for drawing machines G06K15/22, G06F3/13
• CPC Class Codes: G06K 15/22 using plotters

Abstract

An interactive graphics system in which plotting, digitizing and other related capabilities are performed is described in which complex graphics may be generated, edited and developed at a plurality of terminals, independently, with a minimum of hardware and in which precision control of the motion of a plotting table at each location is achieved in response to simplified input commands. Additionally, a novel floating cursor is described by which an operator may control the motion of the carriages of a plotting table or other positioning system actuated during plotting on the table, and digitize various coordinate locations with corresponding storage in a central computer of such locations, all by manually positioning the cursor at the desired locations. The floating cursor is connected with an energy sensor and both the cursor and the sensor are mechanically movable relative to or independently of the carriage. An energy generator is fixedly connected to the carriage and is directed toward the sensor so that relative movement of the cursor and carriage can be detected by the sensor. The carriage is then made to move with the cursor in response to signals generated from the energy sensor. Thus, the cursor floats with respect to the carriage, which precisely follows the cursor over a plotting surface and which carriage contains various devices for drafting or other operations on material located on the plotting surface.

Claims

1. A computer controlled plotting system in which lines and symbols are automatically drawn on a drawing material in response to control signals, which drawing material resides upon a supporting surface of said plotting system, including a carriage assembly movable generally in a plane over said drawing material, said carriage assembly being capable of motion in two generally orthogonal coordinate directions in said plane and at least one writing instrument mounted on said carriage assembly for writing on said drawing material when said carriage is moved in response to said control signals, the improvement comprising:

a cursor manually positionable over said drawing material for indicating the coordinate location of said cursor with respect to said supporting surface, said cursor being operably connected to said carriage assembly such that motion of said cursor with respect to said supporting surface generates said control signals which cause said carriage to move in response thereto, said cursor being mechanically suspended from said carriage assembly and having limited freedom of movement in the two coordinate directions relative to the carriage assembly and the support surface of the plotting system.

2. A plotting system in accordance with claim 1 wherein said cursor comprises a reticle rigidly mechanically connected to a sensing element which senses electromagnetic energy emanating from a source mounted on said carriage such that motion of said sensing element in a plane generally perpendicular to said source causes an error signal to be generated, said error signal being coupled to a carriage positioning means which moves said carriage in response thereto.

3. A plotting system in accordance with claim 2 in which said carriage positioning means includes a servomechanism responsive to said error signal.

4. A plotting system in accordance with claim 3 wherein said carriage assembly includes a first carriage movable over said supporting surface in one of said orthogonal coordinate directions and a second carriage mounted on said first carriage and movable thereon in the other of said orthogonal coordinate directions.

5. A plotting system in accordance with claim 4 wherein said writing instrument and said electromagnetic energy source are mounted on said second carriage and are movable therewith.

6. A plotting system in accordance with claim 2 wherein said sensing element is a photodetector which converts light energy to electrical energy, and wherein said source is a light source.

7. A plotting system in accordance with claim 6 wherein said photodetector includes means for sensing the light energy impinging upon four quadrants thereof and for generating four electrical signals, each of which electrical signals being in response to said light energy in one of said quadrants, and means for comparing said electrical signals such that two positional error signals are generated, each of which positional error signals is indicative of cursor position in one of said mutually orthogonal coordinate directions.

8. A plotting system in accordance with claim 7 further comprising:

means responsive to said two positional error signals for converting said error signals into trains of motor pulses, and servomechanism means for controlling the motion of said carriage assembly in said two orthogonal coordinate directions in response to said motor pulses.

9. A plotting system in accordance with claim 8 wherein said means responsive to said positional error signals includes a pair of voltage controlled oscillators, the frequencies of which are dependent upon said positional error signals, with said frequencies further being directly related to the frequencies of said motor pulses, one of which voltage controlled oscillator frequencies is related to the frequency of said motor pulses in one of said orthogonal coordinate directions and the other of which voltage controlled oscillator frequencies is related to the frequency of said motor pulses in the other of said orthogonal coordinate directions.

10. A plotting system in accordance with claim 5, further including means responsive to the output of said sensing element for generating a pair of error signals, each of which error signals is indicative of cursor position in one orthogonal axis.

11. A plotting system in accordance with claim 10 further comprising means associated with each of said orthogonal axes, each of which means is responsive to one of said error signals for generating motor control signals;

and motors associated with each of said carriages for controlling the motion thereof in response to said motor control signals.

12. A plotting system in accordance with claim 10 wherein said cursor position is stored in said computer.

13. A plotting system in accordance with claim 11 wherein said cursor includes a touch sensitive circuit actuatable upon the physical touching of said cursor, and gating means actuatable by said touch sensitive circuit for enabling said system.

14. A plotting system in accordance with claim 13 wherein said touch sensitive circuit is completed by the resistance of the hand of an operator upon touching said cursor.

15. A plotting system in accordance with claim 13 further including solenoid means for raising said cursor from said drawing material a predetermined distance when plotting.

16. A plotting system in accordance with claim 5 further comprising vacuum holddown means operably associated with said supporting surface for holding said drawing material in close contact therewith.

17. A plotting system in accordance with claim 5 wherein said supporting surface includes a substantially translucent material upon which said drawing material resides and further comprising illumination means mounted behind the opposite surface of said translucent material to which said drawing material resides for illuminating said drawing material.

18. A computer controlled positioning system in which a carriage assembly is automatically positioned to predetermined coordinate locations in a plane generally parallel to a surface in response to control signals from said computer and wherein said carriage assembly includes a tool mounted thereon for working on material positioned on said surface as said carriage assembly moves with respect to said material, the improvement comprising:

a cursor manually positionable with respect to said coordinate locations, said cursor being operably connected to said carriage assembly such that motion of said cursor with respect to said surface generates control signals which cause said carriage to move in response thereto, said cursor being mechanically suspended from said carriage assembly and manually movable by limited amounts relative to the carriage assembly to coordinate locations on the material positioned on said surface.

19. A positioning system in accordance with claim 18 further including energy sensing means mechanically connected to said cursor and energy generating means mounted on said carriage assembly to which said energy sensing means is responsive such that motion of said energy sensing means with respect to said energy generating means is detected and converted into electrical signals;

and means for utilizing said electrical signals for controlling the motion of said carriage assembly.

20. A computer controlled graphics system comprising:

a plotting table for drawing lines and symbols on drawing material mounted on the support surface of the table in response to positioning signals generated by a servomechanism having two coordinate axes extending parallel with the table surface;

a stylus movable in at least two coordinate directions associated respectively with coordinate axes of the servomechanism;

motion conversion means for converting the motion of said stylus into electrical signals;

electronic cursor generation means controlled by said electrical signals for generating a cursor, the location of which with respect to a reference grid is stored by said computer, the reference grid having coordinate axes corresponding respectively with the axes of the servomechanism and the coordinate directions of the stylus, and

counter means, the input of which is coupled to said computer for receiving said stored cursor locations, and the output of which is coupled to said servomechanism for controlling the generation of said positioning signals.

21. A computer controlled graphics system in accordance with claim 20 wherein said electronic cursor generation means comprises a storage cathode ray tube, having a visual display area associated therewith, upon which visual display area said reference grid is located, and wherein said electronic cursor comprises a light spot movable over said visual display area, said light spot being generated by the electron beam of said storage cathode ray tube.

22. A computer controlled graphic system in accordance with claim 20 wherein said positioning signals are generated by a stepping motor.

23. A computer controlled graphics system in accordance with claim 21 wherein said plotting table includes:

a first carriage movable in one coordinate direction a second carriage movably mounted on said first carriage for motion in a coordinate direction orthogonal to said first mentioned orthogonal direction;

a writing assembly mounted on said second carriage including at least one writing instrument, and

motor pulse generation means for generating motor pulses in response to the output of said counter means,

means for controlling said servomechanism in response to said motor pulses,

and means for coupling said positioning signals to said first and second carriages for controlling the motion of said first and second carriages in said orthogonal coordinate directions.

24. A plotting system in accordance with claim 23 further including a cursor positionable over said drawing material for digitizing the coordinate location of said cursor on said material, and means controlled by said electronic cursor for positioning said cursor over said drawing material.

25. A digitizing cursor apparatus for use with an automatic plotting system including:

an energy generation means rigidly mounted to a carriage movable in a first plane;

an energy detector having four energy sensitive quadrants responsive to the output of said energy generation means and movably mounted in a second plane, substantially parallel to said first plane;

a reticle rigidly connected to said energy detector and movable therewith in said second plane;

means connected with the detector for converting the detected energy into an electrical signal indicative of the quantum of energy impinging upon the quadrants of said energy detector; and

means for utilizing said electrical signal to control the motion of said carriage such that said energy generation means is generally centered above the quadrants of said energy detector.

26. A digitizing cursor apparatus in accordance with claim 25 wherein said means for utilizing comprises:

means for converting said electrical signal into a digital control signal; and

a servomechanism controlled by said digital control signal operably connected to said carriage for moving said carriage in said first plane.

27. A digitizing cursor apparatus in accordance with claim 26 wherein said carriage is movable in two coordinate directions in said first plane.

28. A digitizing cursor apparatus in accordance with claim 27 wherein said means for converting is coupled with a counter, and means for storing the contents of said counter.

29. In a device having a support table and a carriage translatable by means of a servomotor over a supporting surface defined by the table, the improvement comprising:

a manually engaged cursor suspended from the carriage for limited freedom of movement relative to the carriage parallel to the supporting surface of the table and having means for signalling manual engagement of the cursor;

sensing means for detecting the relative movement of the cursor and carriage and producing error signals indicative of the relative movement;

servomotor control means connected with the sensing means and the servomotor and responsive to the error signals for driving the servomotor and causing the carriage to follow the cursor over the supporting surface of the table; and

gating means interposed between the sensing means and the servomotor control means and being connected with and responsive to the means for signalling for activating the servomotor control means when the cursor is manually engaged.

30. In a device having the support table and carriage, the improvement of claim 29 wherein the sensing means is mounted on the carriage together with the suspended cursor.

31. In a device having the support table and carriage, the improvement of claim 30 wherein the sensing means comprises a photosensor mounted for movement with the cursor relative to the carriage.

32. The improvement of claim 30 wherein:

the sensing means is a four quadrant photosensor; and

a light source is also mounted on the carriage for illuminating selected areas of the photosensor in accordance with the cursor movements.

33. The improvement of claim 29 wherein means including a counterbalance are provided for suspending the cursor from the carriage in a balanced condition.

34. The improvement of claim 33 wherein the means including the counterbalance includes a tongue plate on which the cursor is mounted and a balance beam pivotally connected to both the carriage and the tongue plate.

35. The improvement of claim 34 further including a damping member extending between the carriage and the tongue plate.

36. The improvement of claim 34 wherein the sensing means is also mounted on the tongue plate.

37. The improvement of claim 29 further including

a meter connected with the servometer control means for measuring the absolute location of the cursor over the supporting surface of the table;

and

data recording means connected with the meter for recording selected locations of the cursor over the supporting surface.

38. The improvement of claim 37 further including a control buttom mounted on the cursor and connected with the data recording means for entering from the meter selected locations of the cursor in the date recording means.