Angular information input system

• US 5,751,229 A
• Filed: 04/13/1995
• Issued: 05/12/1998
• Est. Priority Date: 04/28/1994
• Status: Expired due to Term

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Funahashi, Takahiko
• Primary Examiner(s): Williams, Howard L.
• Application Number:
  US08/421,270
• Time in Patent Office: 1,125 Days
• Field of Search: 341/5, 178/18, 178/19, 345/173
• US Class Current: 341/5
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

An angular information input system detects the inclined angle of a pointing device with a high accuracy without possible errors. This system is constituted so as to detect the induction voltage distribution in each axial direction generated by sensing coils (Ci) arranged under a display screen (16) by electromagnetic wave from a tuning circuit (34) contained in a pointing device (34). This system includes calculating means for calculating normalized values vpax, vpbx, vpay, and vpby in each axial direction by using a ratio between main peak voltage (Vp) representing the pointed coordinate by the pointing device (34) and auxiliary peak voltages (Vpa, Vpb). These normalized values are function parameters for calculating the inclined angles (·θx, θy) in respective axial directions to input data representing the inclined angle θ and inclined direction of the pointing device into the associated computer.

Claims

1. An angular information input system for determining coordinate data and tilt data relating to an inclined angle of a pointing device relative to a coordinate data input device, the angular information input system comprising:

said coordinate data input device, including a plurality of parallel conductors in each of the X and Y axial directions, for inputting coordinate data by detecting electromagnetic signals from said pointing device in each of the X axial direction and the Y axial direction;

said pointing device for indicating location on said coordinate data input device by way of the electromagnetic signals detected via said conductors; and

a calculating means for calculating the incline angle of said pointing device relative to said coordinate data input device in the X axial direction as a function of main peak and auxiliary peak signals detected in each of the X axial direction and the Y axial direction.

2. The angular information input system as set forth in claim 1, wherein the above described calculating means is operated to calculate the inclined angle in the X axial direction of the pointing device in accordance with a function of main peak value and auxiliary peak value of induction voltage in the X axial direction and main peak value and auxiliary peak value of induction voltage in the Y axial direction, and to calculate the inclined angle in the Y axial direction of the pointing device in accordance with a function of main peak value and auxiliary peak value of induction voltage in the X axial direction and main peak value and auxiliary peak value of induction voltage in the Y axial direction, respectively.

3. The angular information input system as set forth in claim 1, wherein the above described calculating means is operated to calculate the inclined angle in the X axial direction of the pointing device in accordance with a function depending on the ratio between main peak value and auxiliary peak value of induction voltage in the X axial direction and the ratio between main peak value and auxiliary peak value of induction voltage in the Y axial direction, and to calculate the inclined angle in the Y axial direction of the pointing device in accordance with a function depending on the ratio between main peak value and auxiliary peak value of induction voltage in the X axial direction and the ratio between main peak value and auxiliary peak value of induction voltage in the Y axial direction, respectively.

4. The angular information input system as set forth in claim 1, wherein the above described coordinate data input device comprises a plurality of sensing coils;

a detecting means for detecting induction voltage generated by the sensing coils; and

a calculating means for calculating the above described main peak value and auxiliary peak from the detected induction distribution.

5. The angular information input system as set forth in claim 4, wherein the above described calculating means calculates the main peak value corresponding to the maximum voltage of the detected induction distribution and the auxiliary peak value corresponding to the induction voltage generated by a specific sensing coil isolated a predetermined distance from the maximum voltage generated coil.

6. The angular information input system of claim 1, wherein said calculating means further includes means for determining said inclined angle in the X axial direction using normalized values resulting from a ratio between a main peak signal and said auxiliary peak signals detected in each of the X axial direction and the Y axial direction.

7. The angular information input system of claim 6, further including means for compensating for the possibility of error at incline angles greater than a predetermined degree by adjusting said calculating means for calculations of incline angles greater than said predetermined degree.

8. The angular information input system of claim 1, wherein said calculating means further includes means for calculating the incline angle of said pointing device relative to said coordinate data input device in the Y axial direction as a function of auxiliary peak signals detected in each of the X axial direction and the Y axial direction.

9. The angular information input system of claim 8, wherein said calculating means further includes means for calculating the incline angles of said pointing device in the X axial direction as a function of main peak signals detected in each of the X and Y axial directions.

10. The angular information input system of claim 1, wherein said pointing device is a stylus and said coordinate data input device is a digitizer tablet.

11. The angular information input system of claim 1 further including means for using said pointing device in the manner of a joystick in order to move the location of a cursor.

12. The angular information input system of claim 11, wherein said pointing device is a stylus, and said stylus includes switching means, which when actuated, is for enabling said stylus to act in a joystick-like manner when tilted in order to move the location of a cursor on a corresponding computer.

13. The angular information input system of claim 1, wherein said pointing device is a stylus and includes a tuning circuit for coupling electromagnetic signals between said coordinate data input device and said pointing device.

14. An angular information input system for determining coordinate data and tilt data relating to an inclined angle of a pointing device relative to a digitizer tablet, the angular information input system comprising:

said digitizer tablet, including a plurality of parallel conductors aligned in at least one axial direction, for inputting coordinate data in X and Y axial directions by detecting electromagnetic signals from said pointing device;

said pointing device for indicating location on said digitizer tablet by way of electromagnetic signals output from said pointing device that are received by said conductors of said digitizer; and

calculation means for calculating the incline angle of said pointing device relative to a surface of said digitizer tablet in each of the X and Y axial directions as a function of normalized values resulting from a function of a ratio between main and auxiliary peak voltages, thereby reducing susceptibility to error in determining incline angle when said pointing device is vertically moved relative to said tablet.