Transducer signal waveshaping system

• US 6,118,205 A
• Filed: 08/13/1998
• Issued: 09/12/2000
• Est. Priority Date: 08/13/1998
• Status: Expired due to Term

• Current Assignee: Luidia Incorporated (Luidia Global Co., Ltd.)
• Original Assignee: Electronics For Imaging Incorporated
• Inventors: Plotkin, Serge, Wood, Robert P., Harel, Jacob, Hou, Alfred Samson
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US09/134,315
• Time in Patent Office: 761 Days
• Field of Search: 310/316.01, 310/316.03, 310/317, 310/318, 310/319
• US Class Current: 310/316.01
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

A transducer signal waveshaping system is provided, in which a signal excitation circuit includes a non-linear device. The resulting circuit produces a short input pulse, which allows a piezoelectric transducer to transmit a shortened output signal having distinct waveshape characteristics. The resulting waveshaped output signal, typically an ultrasonic signal, provides a measurable time-dependent signal that is particularly suited for data entry systems, such as for movable transmitter pens and white boards. The location of the transmitter pen in relation to the writing area of a white board can be determined, using the periodic transmission of the waveshaped output signals. Alternative embodiments include additional circuit elements, which allow the resulting waveshaped output signal to include even more distinctive waveform features. The distinctive waveform features allow the transmitter pen to be located even more accurately, and provide a means for transferring supplementary information, such as pen up vs. pen down distinction, and determined pen characteristics, such as pen color, pen line width, and pen user.

Claims

1. A circuit, connectable to a low voltage source having a first end and a second end, said circuit comprising:

a capacitor having a first side and a second side;

an inductor having a first end and a second end, said first end of said inductor connected to said first side of said capacitor;

means for connecting said first end of said inductor to said first end of said low voltage source;

a non-linear device having a first end and a second end and having a lossy threshold, said first end of said non-linear device connected to said second end of said inductor, said second end of said non-linear device connected to said second side of said capacitor;

a selective switch connected to said second end of said inductor; and

means for connecting said selectable switch to said second end of said low voltage source.

2. The circuit of claim 1, wherein said non-linear device is a zener diode.

3. The circuit of claim 1, wherein said non-linear device is a triac diode.

4. The circuit of claim 1, wherein said non-linear device is a transistor.

5. The circuit of claim 1, wherein said non-linear device is a tunnel diode.

6. The circuit of claim 1, further comprising:

a piezoelectric transducer having a first lead and a second lead, wherein said first lead is connected to said first side of said capacitor, and wherein said second lead is connected to said second side of said capacitor.

7. The circuit of claim 6, wherein said piezoelectric transducer is an ultrasonic piezoelectric transducer.

8. The circuit of claim 1, further comprising:

a secondary capacitor connected between said first end of said inductor and said second end of said inductor.

9. The circuit of claim 1, further comprising:

a secondary inductor connected between said second end of said non-linear device and said second side of said capacitor.

10. The circuit of claim 1, wherein said selective switch is a microprocessor.

11. The circuit of claim 1, wherein said selective switch is a microcontroller.

12. A transducer waveshaping system, comprising:

an oscillation loop formed by a capacitor having a first side and a second side, an inductor having a first end and a second end, said first end of said inductor connected to said first side of said capacitor, and a non-linear device having a first end and a second end, said first end of said non-linear device connected to said second end of said inductor, said second end of said non-linear device connected to said second side of said capacitor;

an input loop formed by a voltage supply circuit connected to a selective switch, said input loop connected between said first end of said inductor and said second end of said inductor;

a first output lead connected to said first side of said capacitor; and

a second output lead connected to said second side of said capacitor.

13. The transducer waveshaping system of claim 12, wherein said non-linear device is a zener diode.

14. The transducer waveshaping system of claim 12, wherein said non-linear device is a triac diode.

15. The transducer waveshaping system of claim 12, wherein said non-linear device is a transistor.

16. The transducer waveshaping system of claim 12, wherein said non-linear device is a tunnel diode.

17. The transducer waveshaping system of claim 12, further comprising:

a piezoelectric transducer having a first lead end and a second lead end, wherein said first lead end is connected to said first output lead, and wherein said second lead end is connected to said second output lead.

18. The transducer waveshaping system of claim 17, wherein said piezoelectric transducer is an ultrasonic piezoelectric transducer.

19. The transducer waveshaping system of claim 12, further comprising:

a secondary capacitor connected between said first end of said inductor and said second end of said inductor.

20. The transducer waveshaping system of claim 12, further comprising:

a secondary inductor located within said oscillation loop.

21. The transducer waveshaping system of claim 12, wherein said selective switch is a microprocessor.

22. The transducer waveshaping system of claim 12, wherein said selective switch is a microcontroller.