Data processing system comprising a graphic tablet and a stylus, and stylus for use in such a system

• US 5,750,939 A
• Filed: 12/06/1995
• Issued: 05/12/1998
• Est. Priority Date: 12/07/1994
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Mateman, Paul, Makinwa, Kofi A.A.
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US08/568,086
• Time in Patent Office: 888 Days
• Field of Search: 178/18, 178/19, 345/173, 345/174, 345/179, 345/180
• US Class Current: 178/18.01
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

In a data processing system including a graphic tablet and a wireless stylus cooperating with the tablet, the stylus transmits an electromagnetic field to be received by the tablet. The stylus has a detector whereby a disturbance of the field, caused by a means external of the stylus, can be detected. The stylus also includes a switch whereby the stylus can be switched to a power-saying standby mode in response to the disturbance. A contactless on/off switch is thus realized for the stylus.

Claims

1. A data processing system, comprising a graphic tablet and a stylus, the stylus including a transmitter for transmitting an electromagnetic field to be received by the tablet and a power supply for powering the stylus, characterized in that:

the stylus comprises a detector for detecting a value of an operating characteristic of the transmitter and a switch coupled to said detector and said power supply for switching the stylus to a standby mode in dependence on said value in order to limit the power supplied by the power supply, and

the system comprises a specially proportioned influencing means externally of the stylus for modifying the electromagnetic field in a direct vicinity of the stylus and modifying the value of said operating characteristic of the transmitter to operate said switch.

2. A system as claimed in claim 1, characterized in that the detector comprises an ammeter for measuring a current to the transmitter, and that the switch is arranged to switch the stylus to the standby mode when the measured current exceeds a threshold current.

3. A system as claimed in claim 2, characterized in that the threshold current is approximately 1.5 times larger than a current flowing to the transmitter during normal operation.

4. A system as claimed in claim 1, characterized in that the detector comprises a field strength measuring device for measuring a field strength near the transmitter, and that the switch is arranged to switch the stylus to the standby mode when the measured field strength exceeds a threshold field strength.

5. A system as claimed in claim 1, characterized in that the influencing means comprises a sleeve which contains metal and which can be arranged on the stylus.

6. A system as claimed in claim 1, characterized in that the influencing means comprises a holder which contains metal and is provided in the tablet.

7. A system as claimed in claim 1, characterized in that the detector comprises a frequency meter for measuring a frequency of a transmitter signal, and that the switch is arranged to switch the stylus to the standby mode when the measured frequency exceeds a threshold frequency.

8. A system as claimed in claim 7, characterized in that the influencing means comprises a sleeve which is provided with an LC circuit and can be arranged on the stylus.

9. A system as claimed in claim 7, characterized in that the influencing means comprises a holder which is provided with an LC circuit and is arranged in the tablet.

10. A system as claimed in claim 1, characterized in that the detector is arranged to execute the detection operation periodically.

11. A stylus for use i a system as claimed in claim 1.

12. A system as claimed in claim 2 characterized in that the influencing means comprises a sleeve which contains metal and which can be arranged on the stylus.

13. A system as claimed in claim 3 characterized in that the influencing means comprises a sleeve which contains metal and which can be arranged on the stylus.

14. A system as claimed in claim 4 characterized in that the influencing means comprises a sleeve which contains metal and which can be arranged on the stylus.

15. A system as claimed in claim 2 characterized in that the influencing means comprises a holder which contains metal and is provided in the tablet.

16. A system as claimed in claim 3 characterized in that the influencing means comprises a holder which contains metal and is provided in the tablet.

17. A system as claimed in claim 4 characterized in that the influencing means comprises a holder which contains metal and is provided in the tablet.

18. A system as claimed in claim 2 characterized in that the detector is arranged to execute the detection operation periodically.

19. A system as claimed in claim 3 characterized in that the detector is arranged to execute the detection operation periodically.

20. A stylus for use in a system as claimed in claim 2.