Position detection system

• US 20020047833A1
• Filed: 10/23/2001
• Published: 04/25/2002
• Est. Priority Date: 10/24/2000
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Watanabe, Kazuhiro, Kitada, Takashi
• Granted Patent: US 6,798,403 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member

Abstract

A system for detecting a position of a stylus movable on an interactive board includes a position information transmitter and information detection sections. The stylus has the transmitter for transmitting to the detection sections electromagnetic wave signals or light signals, and ultrasonic wave signals. The position is detected based on measurement of direct distances for signal transmission between the stylus and the detection sections. The detected position information is output to a personal computer, image projector, printer, etc. Each detection section has an opening sized so that the ultrasonic waves are advantageously transmitted through the opening and substantially radially from its center to its piezoelectric element.

Claims

1. A position detection system for detecting a position of an object movable to fixed detection means, said system comprising:

signal transmitter means provided at said movable objet and generating to transmit signals of electromagnetic wave and ultrasonic wave to said detection means;

first and second detection means for constituting said fixed detection means, said first detection means receiving to detect a signal of electromagnetic wave transmitted from said transmitter means, and said second detection means including detection elements for detecting a signal of ultrasonic wave transmitted from said transmitter means; and

position detection means for detecting a position of said movable object provided with said transmitter means by computing positional data of said object based on detecting a difference between the detection of the transmitted waves of said first and said second detection means;

wherein said second detection means defines an opening for passing to further transmit therethrough the transmitted signal of ultrasonic wave to said detection element by making the further transmitted ultrasonic wave propagate radially from a center of said opening to said detection element.

2. A position detection system as claimed in claim 1, wherein said transmitter means generate to transmit sequential light signals as the electromagnetic wave signal and wherein said first detection means receives a first light signal and thereafter a second light signal.

3. A position detection system as claimed in claim 2, further including a display and color designation means for detecting a time difference between said first light signal and said second light signal received by said first detection means in order to designate a color display of the detected position.

4. A position detection system as claimed in claim 1, wherein said transmitter means transmits said electromagnetic wave and said ultrasonic wave simultaneously.

5. A position detection system as claimed in claim 1, wherein said first detection means and said second detection means are provided with means for generating timing signals.

6. A position detection system as claimed in claim 1, wherein said second detection means includes amplification means for receiving and amplifying the transmitted ultrasonic wave signal.

7. A coordinates detection system for detecting coordinates of an object movable to fixed detection means, said system comprising the fixed detection means, signal wave transmitter means and coordinates detection means, wherein:

said signal wave transmitter means is provided at said movable objet and generates to transmit signals of electromagnetic wave and ultrasonic wave to said detection means;

said fixed detection means comprises first and second detection means, said first detection means receiving and detecting a signal of electromagnetic wave transmitted from said transmitter means, and said second detection means detecting a signal of ultrasonic wave transmitted directly from said transmitter means;

said coordinates detection means detecting coordinates of a position of said movable object provided with said transmitter means by detecting a time difference between the detection of the transmitted waves of said first and said second detection means;

said second detection means defining an opening for passing therethrough to further transmit the transmitted signal of ultrasonic wave to said detection element by making the transmitted ultrasonic wave propagate radially from a center of said opening to said detection element.

8. A coordinate detection system as claimed in claim 7, wherein said coordinate detection means includes amplification means having an amplification factor to be changed for amplification of the transmitted ultrasonic wave signal in dependence upon the detected coordinates of the object position.

9. A coordinate detection system as claimed in claim 7, wherein said coordinate detection means includes storage means for storing the detected coordinates of said movable object.

10. A coordinate detection system as claimed in claim 9, wherein said coordinate detection means selects a gain factor or a slice level for generation of a timing signal depending on position coordinates read out from said storage means.

11. A coordinate detection system as claimed in claim 8, wherein said coordinate detection means defines and partitions a coordinate space into a predetermined number of areas, said movable object being moved in said areas, said coordinate detection means include means for determining different gain factors depending on said areas.

12. A coordinate detection system as claimed in claim 8, wherein said coordinate detection means includes means for selectively applying a gain factor for the amplification of the signal of transmitted ultrasonic wave in dependence upon a position area in which said transmitter means exists.

14. A display system as claimed in claim 13, further comprising reading means for reading images at least written on said board means.

15. A display system as claimed in claim 14, further comprising output means for outputting information at least of said images read by said reading means.

16. A display system as claimed in claim 13, further including means for executing PC operations such as switching of images displayed on said display means from said board means by operating said writing means.

17. A display system as claimed in claim 13, wherein letters etc. can be written on said board means even if said writing means is one having marking function.

18. A display system as claimed in claim 13, further comprising conveying means for conveying drawing means.

19. A display system as claimed in claim 14, further comprising data sending means for sending data obtained by said reading means to said computer.

13. A display system comprising:

board means and writing means movable thereon for generating to transmit signals of electromagnetic wave and ultrasonic wave, thereby transmitting information of a position of said writing means on said board;

first detection means for detecting a signal of electromagnetic wave transmitted from said writing means;

second detection means for detecting a signal of said ultrasonic wave transmitted from said writing means;

position detection means for detecting a position of said writing means on said board means based on signal detection results of said first detection means and said second detection means;

storage means for storing position information detected by said position detection means;

a computer having display means; and

transmission means for transmitting said position information stored in said storage means to said computer and enabling said display means based on the transmitted position information;

wherein

said second detection means defines an opening for passing to further transmit therethrough the transmitted signal of ultrasonic wave to said detection element by making the further transmitted ultrasonic wave propagate radially from a center of said opening to said detection element.