US3535447A

US3535447A - Inductively coupled telautograph apparatus with stylus angle compensation

Info

Publication number: US3535447A
Application number: US680680A
Authority: US
Inventors: Arthur E Wollrich
Original assignee: Hughes Aircraft Co
Current assignee: Raytheon Co
Priority date: 1967-11-06
Filing date: 1967-11-06
Publication date: 1970-10-20
Anticipated expiration: 1987-10-20

Description

Q -Z 1970 A. E. woLLRlcl-l I ,5

INDUCTIVELY COUPLED TELAUTOGRAPH APPARATUS I 7 WITH STYLUS ANGLE COMPENSATION Filed Nov. 6, 1967 2 Sheets-Sheet 1 zz 1 /z Z// 1/ fi/ 1 I /0 1 I Wrurae ,4emuz4. l l/azzz/cw,

Irma/es! Oct. 20; 1970 Filed Nov. 1967.

A. E. WOLLRICH,

INDUCTIVELY COUPLED TELAUTOGRAPH APPARATUS WITH STYLUS ANGLE COMPENSATION I 2 SheetS -Sheet 2 United States Patent US. Cl. 178-19 10 Claims ABSTRACT OF THE DISCLOSURE The structure teaches an arrangement to display manually created characters at a location remote from the creating area. A writing board is provided having a plurality of pickup coils arranged at opposite ends of the X and Y axes of the board. Each coil comprises a 'first segment in generally planar relation with the writing board and a second segment in angular relation to the first segment. A writing instrument contains a switch activated by the tip of the instrument, the latter closing an oscillating c rcuit. The alternating frequency emanating from the 0861ilator induces signals in the described X and Y coils. The comparative signal strength within the coils locates the position of the writinginstrument on the writing area. The signals are used to operate a remote display arrangement such as an oscilloscope. The writing instrument 18 provided with a secondary switch which may be manually closed to change the frequency of the emitted slgnal and thereby 'create a shutoff signal for the remote display.

A character display arrangement is disclosed having a manually operable pen which is used to form characters on a display board. A plurality of pickup coils are peripherally arranged around the writing surface of the board. A manually operable writing pen is provided having an oscillator therein. The pen tip engaging the writing surface energizes the oscillator which emanates a magnetic field at a first frequency, inducing voltage signals in the peripherally arranged coils. The relative signal output from the coils indicates the position of the pen on the writing surface. The signals may be used to deflect the electron writing beam of a storage or other oscilloscope and thereby display the characters formed on the writing board.

The invention relates to a device to create output signals varying in intensity in direct relation to the position of manually formed characters on a writing surface, the signals being useable to control the electron beam of a storage oscilloscope for remote display of the characters formed.

In describing the herein-disclosed device, for simplicity purposes, reference will be had to forming written characters on a writing board for remote display on a storage oscilloscope or other display device, e.g., a plotting device. However, it will be understood that any type of character may be displayed, that is, writing, drawings pictures, coded signals, or the like.

Devices of the type here under consideration have been developed in the prior art. For example, a device denominated Scriptoscope was built as early as 1952 as evidenced by an article appearing at pages 144 and 145 in the July 1952 issue of Electronics magazine. While these prior art devices displayed operating characteristics which were generally satisfactory, the present invention presents importantly improved features relative thereto. For example, prior art writing and display devices produced distortions of the characters manually formed which resulted from the movement of the writing instrument in space because of the mode in which the writer held the instrument in his hand. Additionally, the writing instrument employed in the prior art devices required extended wire lead lines to power the unit and provide the control circuitry to completely complement the operating characteristics of the related oscilloscope.

Accordingly, it is a primary object of the invention to provide a remote writing and display arrangement which eliminates the disadvantages associated with prior art devices.

It is a further object of the invention to provide a device of the type described which minimizes display distortions inherent in the prior art arrangements and thus provides an extremely accurate remote display of the characters manually created by a writing instrument.

It is yet a further object of the invention to provide a writing and display arrangement of the type described which has a novel arrangement of pickup coils physically associated with a writing area to provide means for signal compensation resulting from the variable movement in space of the writing instrument as the characters are created.

It is yet a further object of the invention to provide a writing and display arrangement of the type described having a completely independent writing instrument, thus eliminating the need for the electrical wire leads characteristic of the prior art arrangements.

These and other objects and features of the invention will become apparent in the course of the following description and from an examination of the related drawings wherein:

FIG. 1 is a perspective view of a writing table incorporating the invention;

FIG. 2 is a schematic perspective view of a typical coil configuration employed in the structure of FIG. 1;

FIG. 3 is a circuit diagram of the electrical component of the writing instrument utilized in the invention;

FIG. 4 is a fragmentary, partially schematic view of a typical switching arrangement which may be employed in She writing instrument used in the disclosed invention; an

FIG. 5 is a schematic logic and electrical block diagram of the circuitry utilized in the invention.

Describing the invention in detail and directing attention to the figures, numeral 10 generally indicates a writing table which comprises a housing 12 physically encapsulating the major components of the invention. The housing 12 is provided with a central writing surface 14 on which may be positioned a piece of paper, or the like, upon which may be manually drawn desired characters or other written information. The writing surface 14 of course forms part of an upper surface 16 of the housing 12. A plurality of signal pickup coils are positioned peripherally around and in close juxtaposition to the writing surface 14. The coils are shown schematically to simplify invention disclosure. In a preferred embodiment a pair of left-

right coils

18 and 20 are positioned on either side of the writing surface 14. Additionally, another pair of up-

down coils

22 and 24 are positioned immediately adjacent the top and bottom edge of the writing surface 14.

Coils

18 and 20 may be alternately denominated the X- axis coils, while

coils

22 and 24 may be denominated Y- axis coils. In addition, a single coil 26 is positioned immediately adjacent the writing surface 14 and totally surrounding the latter. Its purpose will be subsequently described.

Referring to FIG. 2, a preferred physical coil construction is here shown. It will be understood that all of the

coils

18, 20, 22, and 24 are physically constructed in a similar manner. Accordingly, only the structure of coil 18 is shown in detail in FIG. 2. Coil 18, shown in FIG. 2, comprises a first winding segment 18a which is formed in a plane parallel to the surface 16 of the housing and, therefore, in a plane closely related to and parallel with the writing surface 14. Coil 18 additionally comprises a second winding segment 18b which is formed in a plane perpendicular to the plane of coil segment 18a. The purpose of this physical relation of the separate coil segment will hereinafter be described in detail but coil segment 18a may, for convenience, be called the primary signal pickup coil while the coil segment 18b may be called the pen-tilt correction-signal pickup segment.

Turning to FIGS. 3 and 4, it will be seen that a conventional writing instrument is shown fragmentarily at and comprises a writing ball tip 32 which engages the writing surface 14 in the conventional manner. The tip of the writing instrument 30 is provided with a coil formed therein, as at 34, the latter having its exposed ends connected to a normally open switch 36. It will be apparent that when the writing instrument 30 is physically pressed against the surface 14 the ball 32 will move axially the writing instrument 30 and close the switch 36 thereby energizing the coil 34 as is shown in circuit diagram of FIG. 3. Typically, the circuit of FIG. 3 is a conventional oscillator circuit employing a solid-state transistor device 37. In a preferred embodiment of the invention power is supplied by an independent battery 38 thereby eliminating the need for wire-fed power supply to the writing instrument. The circuit additionally comprises capacitors 40, 40, resistance 42, and a pair of normally open switching devices 36 and 46. It will be noted the switching device 36 represents and is identical with that actuated by the ball 32 of the writing instrument 30.

In normal operation, the Writing instrument 30 is hand manipulated over the writing surface 14 which closes switch 36 energizing the coil 34 of the oscillator circuit shown in FIG. 3. As a result of operation of the oscillating circuit of FIG. 3, an alternating magnetic field is created by the writing instrument 30 and at a first frequency determined by the characteristics of the circuit of FIG. 3, as will be well understood by those familiar with this art. The alternating magnetic field expanding and contracting from the writing surface 14 inductively locks with pickup coils 18, 20, 22, and 24 inducing a voltage signal therein. The signal created in the X-axis pair of pickup coils 18 and 20 has a strength in the respective coils directly proportional to the X-position of the writing instrument on the writing surface 14. Similarly, the respective signal strength induced in X-axis pickup coils 22 and 24 is directly proportional to the Y position of the Writing instrument 30 on the writing surface 14. It will be obvious that the relative signal strength, therefor, will continuously vary as the X-Y position of the writing instrument is varied over the writing surface 14.

In describing the typical coil construction of FIG. 2, it will be recalled that a coil structure in perpendicular planes was said to be presently preferred. It will be apparent that the writing instrument 30, when being manually manipulated over the write surface 14, will normally be aligned in an acute angle relative to that surface. It has been found that if just parallel plane coils such as those shown in 18a in FIG. 2 are used, that a signal distortion results because of the angle of holding the writing instrument. Accordingly, coil segment 18b is positioned in a plane perpendicular to the plane of coil segment 18a and, in this position, will normally have a minimum signal induced therein when the pen is held perpendicular to the writing surface 14. As the pen is moved from said perpendicular position to an acute angular position relative to writing surface 14, the signal induced in writing segment 18a is diminished while the signal induced in writing segment 18b is increased. However, the total signal emanating from the coil 18 represents the sum of the signals in the respective coil segments 18a and 18b and therefore the total output signal of the coil is unaffected by the variable tilting of the pen during the manual writing manipulation. Similarly, the total signal induced in coil-

s

20, 22, and 24 compensates for pen tilt.

Directing attention to FIG. 5, the

coils

18, 20, 22, 24, and 26 are schematically indicated therein. The Y-

axis coils

22 and 24 each deliver their signal to an amplifierrectifier combination indicated at 50 and 52. The DC. signals from rectifiers 50 and 52 are delivered to

nonlinear amplifiers

54, 58, the latter delivering signals to the adder 56. The two signals are arithmetically combined in the adder 56 and an output signal emanates therefrom to control the vertical deflection of a conventional electron beam of an associated oscilloscope. Similarly, coils 18 and 20 have their output signals delivered to

amplifiers

60 and 62. The output of the amplifiers is conducted to

rectifiers

64 and 66. respectively, and the DC current emanating therefrom is carried to

nonlinear amplifiers

68 and 70, the output of the latter being arithmetically summed in the adder 72. The summing in the adder 72 produces an output signal which controls the horizontal deflection of the associated oscilloscope electron beam. In addition, the signals from

amplifiers

60 and 62 arising from the closing of switch 36 as the writing process begins may be carried to amplifier mixer 74 and the output therefrom rectified as at 36. The rectified signal is passed via low-pass filter 78 to a conventional control device which operates merely to turn on the electorn beam.

Recalling that the display device is a conventional storage tube oscilloscope, a mode to erase the written image must be provided. The writing device 30 may be provided with an independent manually-operated switch 46, the latter being closeable by the writer to provide an alternate frequency output from the coil 34 by shorting capacitor 41 from the circuit comprising capacitors 40, 41 connected in series. This output induces a signal in coil 26 is tuned to this alternate frequency thus providing signal which is amplified in amplifier 80, rectified in rectifier 82, and passed via low-pass filter 84 to a conventional control device at the oscilloscope which will provide a negative bias at the oscilloscope grid turning off the electron grid. It will be understood that no signal will be induced in coil 26 by the writing process so an erase signal cannot be generated without positive action by the writer.

The invention as shown and described is by way of illustration and not limitation and my be modified in many respects, all within the scope and spirit thereof.

What is claimed is: 1. In a sensing arrangement adapted to display created characters at a remote display device, the combination of: a character-creating area, plural coil means positioned in predetermined juxtaposition to the area, each of said coil means having an axis and additionally including no less than one turn on the same side of said area, said no less than one turn being disposed parallel to a plane oriented at an angle with said area and intersecting said axis,

character-creating means adapted to emanate an alternating magnetic field of constant amplitude thereby to induce electrical signals in all of said coil mean-s as a result of cooperation with the creating area, the induce signals in the respective coil means having variable intensity as a function of the position of said character-creating to reflect the position thereof in the creating area,

and means coupled to said plural coil means for generating variable-intensity direct-current signals adapted to actuate said display device and thereby reproduce the characters created.

2. A sensing arrangement according to claim 1, wherein said plural coil means comprises first and second coils oriented to the X-axis of the creating area and third and fourth coils oriented to the Y-axis of the creating area.

3. A sensing arrangement according to claim 2 wherein the first and second coils are positioned on opposed sides of the creating area and the third and fourth coils are positioned on other opposed sides of the creating area,

said first and second coils being arranged in perpendicular relationship to said third and fourth coils. 4. A sensing arrangement according to claim 3, wherein,

the display device is an oscilloscope having a display face and an electron beam to illuminate said face,

the signals emanating from the first and second coils controlling the movement of the oscilloscope electron beam in one direction and the signals emanating from the third and fourth coils controlling the oscilloscope electron beam in a direction perpendicular to said first-mentioned direction.

5. A sensing arrangement according to claim 4, wherein first and second turns of the respective first, second,

third, and fourth coils are arranged in perpendicular relation to each other,

one of said first and second turns in each coil being in planar alignment with said creating area.

6. A sensing arrangement according to claim 5, wherein said means coupled to said plural coil means includes circuit means wherein the variable signals from the first and second coils are electronically rectified and summed in a first adder and the variable signals from the third and fourth coils are electronically rectified and summed in a second adder, the signals from the respective first and second adders being adapted to control the electron beam of said oscilloscope.

7. A sensing arrangement according to claim 1, wherein said character-creating means comprises a writing device adapted to energize an electronic oscillating circuit in response to physical contact with the creating area.

8. A sensing arrangement according to claim 7, wherein said writing device includes switch means in said oscillating circuit which may be manually energized to provide a second alternating magnetic field,

and oscilloscope control coil mean-s in juxtaposition with said creating area to receive said second alternating magnetic field thereby to generate an erase signal.

9. In a pickup arrangement adapted to display created created characters at a remote oscilloscope by controlling the electron beam thereof, the combination of a writing area,

X-axis coil means positioned on opposed sides of the writing area,

Y-axis coil means positioned on other opposed sides of the writing area,

each of said coil means comprising a first coil segment positioned in planar relationship with the writing area and a second coil segment sensitive on a parallel axis positioned in perpendicular relation to the writing area,

a writing device comprising a tip adapted to actuate a switch upon engaging the writing area and close a battery-powered oscillating circuit to create an alternating magnetic field of constant amplitude and at a first frequency, said alternating magnetic field being operative to induce electrical signals in the respective coil means having variable intensities that are a function of the position of the writing device in the writing area,

means responsive to said variable intensity signals from the X-axis coil means for generating a first variable-intensity direct-current signal adapted to control the electron beam of said oscilloscope in one direction; and

means responsive to the variable intensity signals from the Y-aXis coil means for generating a second variable-intensity direct-current signal adapted to control the oscilloscope electron beam in an orthogonal direction, whereby the characters created at the writing area are displayed on said oscilloscope.

10. A sensing arrangement according to claim 9, and

including,

another manually operated switch associated with said wiring device adapted upon closure to change the frequency of said alternating magnetic field of constant amplitude in said oscillating circuit to a second frequency, and

a beam control coil associated with the writing area and tuned to said second frequency to create an induced signal in response to said second frequency alternating magnetic field, the last-mentioned created signal being adapted to control the presentation of said display.

References Cited UNITED STATES PATENTS 2,000,014 5/1935 DuMont 178-18 2,914,610 11/1959 Leitner et al. 17819 OTHER REFERENCES A. G. Hubby et al., Scriptoscope Shows Messages on C-R Tube; Electronics, July 1952, pp. l44l45.

ALVIN H. WARING, Primary Examiner M. M. CURTIS, Assistant Examiner U.S. C1.X.R.