Position information detection system and position information detection method

• US 7,786,936 B2
• Filed: 06/28/2007
• Issued: 08/31/2010
• Est. Priority Date: 07/20/2006
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kurokawa, Yoshiyuki
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US11/819,578
• Publication Number:
  US 20080174492A1
• Time in Patent Office: 1,160 Days
• Field of Search: 342/451, 342/458, 342463-465, 455/456.1, 455/457
• US Class Current: 342/458
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0215 Interference

Abstract

An object of the present invention is to achieve a position information detection system with high precision when an obstruction and a reflective object exist. A position information detection system includes a reader/writer whose position is known, a first RF chip whose position is known, and a second RF chip attached to an object to be detected; and calculates a distance between the reader/writer and the second RF chip from a first calculated distance between the reader/writer and the first RF chip, which is calculated from a signal intensity of a communication signal transmitted from the reader/writer, detected by the first RF chip, a second calculated distance between the second RF chip and the reader/writer, which is calculated from a signal intensity of a communication signal transmitted from the reader/writer, detected by the second RF chip, and a distance between the reader/writer and the first RF chip.

Claims

1. A position information detection system comprising:

a first RF chip;

a second RF chip; and

a reader/writer which transmits and receives data by transmission and reception of a radio signal to/from the first RF chip and the second RF chip,

wherein the first RF chip has a function to detect a first signal intensity of a radio signal transmitted from the reader/writer, a function to calculate a first calculated distance from the first signal intensity, and a function to transmit data on the first calculated distance to the reader/writer;

wherein the second RF chip has a function to detect a second signal intensity of a radio signal transmitted from the reader/writer, a function to calculate a second calculated distance from the second signal intensity, and a function to transmit data on the second calculated distance to the reader/writer; and

wherein the reader/writer has a function to calculate a position of the second RF chip from the first calculated distance, the second calculated distance, a position of the first RF chip, and a position of the reader/writer.

4. The position information detection system according to claim 1, wherein the reader/writer has a function to compare the first calculated distance with the position of the first RF chip, and a function to calculate the position of the second RF chip from the second calculated distance and the position of the reader/writer, based on a comparison of the first calculated distance with the position of the first RF chip.

7. The position information detection system according to claim 1, wherein the first RF chip or the second RF chip has a function that a power supply voltage is supplied from the radio signal.

10. The position information detection system according to claim 1, wherein the first RF chip, the second RF chip, or the reader/writer is comprised of a transistor including a semiconductor film provided over a substrate.

16. The position information detection system according to claim 1, wherein the first RF chip or the second RF chip is comprised of a MOS transistor on a single crystalline substrate.

2. A position information detection system comprising:

a first RF chip;

a second RF chip; and

a reader/writer which transmits and receives data by transmission and reception of a radio signal to/from the first RF chip and the second RF chip,

wherein the first RF chip has a function to detect a first signal intensity of a radio signal transmitted from the reader/writer and a function to transmit data on the first signal intensity to the reader/writer;

wherein the second RF chip has a function to detect a second signal intensity of a radio signal transmitted from the reader/writer and a function to transmit data on the second signal intensity to the reader/writer; and

wherein the reader/writer has a function to calculate a first calculated distance from the first signal intensity, a function to calculate a second calculated distance from the second signal intensity, and a function to calculate a position of the second RF chip from the first calculated distance, the second calculated distance, a position of the first RF chip, and a position of the reader/writer.

5. The position information detection system according to claim 2, wherein the reader/writer has a function to compare the first calculated distance with the position of the first RF chip, and a function to calculate the position of the second RF chip from the second calculated distance and the position of the reader/writer, based on a comparison of the first calculated distance with the position of the first RF chip.

8. The position information detection system according to claim 2, wherein the first RF chip or the second RF chip has a function that a power supply voltage is supplied from the radio signal.

11. The position information detection system according to claim 2, wherein the first RF chip, the second RF chip, or the reader/writer is comprised of a transistor including a semiconductor film provided over a substrate.

17. The position information detection system according to claim 2, wherein the first RF chip or the second RF chip is comprised of a MOS transistor on a single crystalline substrate.

3. A position information detection system comprising:

a first RF chip;

a second RF chip; and

a reader/writer which transmits and receives data by transmission and reception of a radio signal to/from the first RF chip and the second RF chip,

wherein the reader/writer has a function to detect a first signal intensity of a radio signal transmitted from the first RF chip, a function to calculate a first calculated distance from the first signal intensity, a function to detect a second signal intensity of a radio signal transmitted from the second RF chip, a function to calculate a second calculated distance from the second signal intensity, and a function to calculate a position of the second RF chip from the first calculated distance, the second calculated distance, a position of the first RF chip, and a position of the reader/writer.

6. The position information detection system according to claim 3, wherein the reader/writer has a function to compare the first calculated distance with the position of the first RF chip, and a function to calculate the position of the second RF chip from the second calculated distance and the position of the reader/writer, based on a comparison of the first calculated distance with the position of the first RF chip.

9. The position information detection system according to claim 3, wherein the first RF chip or the second RF chip has a function that a power supply voltage is supplied from the radio signal.

12. The position information detection system according to claim 3, wherein the first RF chip, the second RF chip, or the reader/writer is comprised of a transistor including a semiconductor film provided over a substrate.

18. The position information detection system according to claim 3, wherein the first RF chip or the second RF chip is comprised of a MOS transistor on a single crystalline substrate.

13. A position information detection method comprising:

transmitting a first radio signal from a reader/writer to a first RF chip, and transmitting a second radio signal from the reader/writer to a second RF chip;

receiving the first radio signal and detecting a first signal intensity of the first radio signal in the first RF chip, and receiving the second radio signal and detecting a second signal intensity of the second radio signal in the second RF chip;

calculating a first calculated distance from the first signal intensity in the first RF chip, and calculating a second calculated distance from the second signal intensity in the second RF chip;

transmitting data on the first calculated distance from the first RF chip to the reader/writer, and transmitting data on the second calculated distance from the second RF chip to the reader/writer;

receiving data on the first calculated distance, comparing the first calculated distance with a position of the first RF chip, and determining a correction method of a calculated distance based on a comparison of the first calculated distance with the position of the first RF chip, in the reader/writer; and

receiving data on the second calculated distance and calculating a position of the second RF chip from the second calculated distance and a position of the reader/writer, based on the correction method, in the reader/writer.

14. A position information detection method comprising:

transmitting a first radio signal from a reader/writer to a first RF chip, and transmitting a second radio signal from the reader/writer to a second RF chip;

receiving the first radio signal and detecting a first signal intensity of the first radio signal in the first RF chip, and receiving the second radio signal and detecting a second signal intensity of the second radio signal in the second RF chip;

transmitting data on the first signal intensity from the first RF chip to the reader/writer, and transmitting data on the second signal intensity from the second RF chip to the reader/writer;

receiving data on the first signal intensity, calculating a first calculated distance from the first signal intensity, comparing the first calculated distance with a position of the first RF chip, and determining a correction method of a calculated distance based on a comparison of the first calculated distance with the position of the first RF chip, in the reader/writer; and

receiving data on the second signal intensity, calculating a second calculated distance from the second signal intensity and calculating a position of the second RF chip from the second calculated distance and a position of the reader/writer, based on the correction method, in the reader/writer.

15. A position information detection method comprising:

transmitting a first radio signal from a first RF chip to a reader/writer, and transmitting a second radio signal from a second RF chip to the reader/writer;

receiving the first radio signal and detecting a first signal intensity of the first radio signal, and receiving the second radio signal and detecting a second signal intensity of the second radio signal, in the reader/writer;

calculating a first calculated distance from the first signal intensity, comparing the first calculated distance with a position of the first RF chip, and determining a correction method of a calculated distance based on a comparison of the first calculated distance with the position of the first RF chip, in the reader/writer; and

calculating a second calculated distance from the second signal intensity, and calculating a position of the second RF chip from the second calculated distance and a position of the reader/writer, based on the correction method, in the reader/writer.