Patent EP0308964A2 successfully refreshed from Google Patents.
EP0308964A2
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EP
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Radio-frequency identification system
Assignee: Fujitsu Ltd
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Filing: 1988-09-23
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Granted: —
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Expires: 2008-09-23
Abstract
Abstract A radio-frequency identification (RF-ID) system including a master unit and a sub unit connected thereto by radio-communication, and used for identifying a moving article on which the sub unit is mounted. The master unit transmits a circularly polarized wave having two carrier components (CW1, CW2), and the sub unit, which does not include carrier generators and branching filters, and is powered by a battery provided therein, receives the circularly polarized wave, separates the two carrier components by a hybrid circuit (312,321), and transmits another circularly polarized wave base upon the received carrier component. The sub unit may be operated in response to a starting command from the main unit, and the main unit may have first and second detecting units separated by n·λg/8, n: an odd integer, and λg: effective wave length, to eliminate the occurrence of null point phenomenon.
Inventors
- 👤 Hideo Sugawara
- 👤 Hideo Ashida
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 04:20
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/067; G06K19/07; G06K19/077; G06K19/07749; G06K19/07773; G06K19/07786; G01; G01S; G01S13/00; G01S13/74; G01S13/75; G01S13/751; G01S13/758; G01S13/82; G01S13/825; G01S7/00; G01S7/02; G01S7/024; G01S7/026; G06K7/00; G06K7/0008; G06K7/10; G06K7/10009; G06K7/10316
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
273 words
A radio frequency identification system comprising: a main unit including a main modulation and demodulation (modem) portion (11, 12), a main transmission portion (21) and a main reception portion (22); and a sub unit, radio communicatable with said main unit through a radio-communication channel, including a sub reception portion (31), a sub modem portion (4), a sub transmission portion (32), and a small size battery supplying power to said sub reception portion, said modem and said transmission portion, said main modem portion outputting a first modulation signal (P1mod) modulated a first transmission data (D1t) with a first carrier (CW1) having a first frequency (f₁) and a second carrier (CW2) having a second frequency (f₂) close to said first frequency; said main transmission portion receiving said first modulation signal and said second carrier and generating a first circularly poalrization wave having a first rotation, on the basis of said received first modulation signal and said second carrier, said sub reception portion receiving said first circularly polarization wave and separating into said first modulation signal and said second carrier, said sub modem portion demodulating said first modulation signal to recover said first transmission data, said sub modem portion modulating a second transmission data (D2t) with said separated second carrier to output a second modulation signal (P2 mod), said sub transmission portion generating a second circularly polarization wave having a rotation equal to said first rotation on the basis of said second modulation signal, said main reception portion receiving said second circularly polarization wave and outputting said second modulation signal, and said main modem portion demodulating said second modulation signal to recover said second transmission data.
Claim 2
Dependent Claim
273 words
A radio frequency identification system comprising: a main unit including a main modulation and demodulation (modem) portion (11, 12), a main transmission portion (21) and a main reception portion (22); and a sub unit, radio communicatable with said main unit through a radio-communication channel, including a sub reception portion (31), a sub modem portion (4), a sub transmission portion (32), and a small size battery supplying power to said sub reception portion, said modem and said transmission portion, said main modem portion outputting a first modulation signal (P1mod) modulated a first transmission data (D1t) with a first carrier (CW1) having a first frequency (f₁) and a second carrier (CW2) having a second frequency (f₂) close to said first frequency; said main transmission portion receiving said first modulation signal and said second carrier and generating a first circularly poalrization wave having a first rotation, on the basis of said received first modulation signal and said second carrier, said sub reception portion receiving said first circularly polarization wave and separating into said first modulation signal and said second carrier, said sub modem portion demodulating said first modulation signal to recover said first transmission data, said sub modem portion modulating a second transmission data (D2t) with said separated second carrier to output a second modulation signal (P2 mod), said sub transmission portion generating a second circularly polarization wave having a rotation equal to said first rotation on the basis of said second modulation signal, said main reception portion receiving said second circularly polarization wave and outputting said second modulation signal, and said main modem portion demodulating said second modulation signal to recover said second transmission data.
Claim 3
Dependent Claim
24 words
A radio frequency identification system according to claim 1, wherein said first and second frequencies are within approximately 0.1 to several tens giga hertz.
Claim 4
Dependent Claim
22 words
A radio frequency identification system according to claim 2, wherein said main modem portion comprises an amplitude shift keying (ASK) modulator (111).
Claim 5
Dependent Claim
27 words
A radio frequency identification system according to claim 3, wherein said main transmission portion comprises a first printed hybrid circuit (211) and a first printed antenna (212).
Claim 6
Dependent Claim
27 words
A radio frequency identification system according to claim 4, wherein said sub reception portion comprises a second printed antenna (311) and a second printed hybrid circuit (312).
Claim 7
Dependent Claim
33 words
A radio frequency identification system according to claim 3, wherein said sub modem portion comprises a phase shift keying (PSK) modulator (41), and wherein said main modem portion comprises a PSK demodulator (121).
Claim 8
Dependent Claim
43 words
A radio frequency identification system according to claim 6, wherein said sub transmission portion comprises said second printed hybrid circuit (211), and said second printed antenna (212), said second printed antenna being commonly used, and said second printed hybrid circuit being commonly used.
Claim 9
Dependent Claim
40 words
A radio frequency identification system according to claim 7, wherein said main reception portion comprises said first printed antenna and said first hybrid circuit, said first printed antenna being commonly used, and said first printed hybrid circuit being commonly used.
Claim 10
Dependent Claim
57 words
A radio frequency identification system according to claim 3, wherein said sub modem portion comprises a frequency shift keying (FSK) modulator (41A) and a PSK modulator (41B) connected to said FSK modulator in series, and wherein said main modem portion comprises a PSK demodulator (121) and a FSK demodulator (122) connected to said PSK demodulator in series.
Claim 11
Dependent Claim
37 words
A radio frequency identification system according to claim 1, wherein said sub unit comprises a data processing portion, operatively connected to said sub modem portion, for storing said first transmission data and outputting said second transmission data.
Claim 12
Dependent Claim
42 words
A radio frequency identification system according to claim 1, wherein said sub unit is radio-connected to a master unit for providing data to be stored in said data processing portion and being said second transmission data, through said transmission and reception portions.
Claim 13
Dependent Claim
150 words
A radio frequency identification system according to claim 1, wherein said sub modem (4) comprises a sub demodulation portion for demodulating the first modulation signal and a sub modulation portion for modulating the second transmission data with the separated second carrier, wherein said main modem portion outputs a starting modulation signal modulated a start data with the first carrier, and said main transmission portion generates a starting circularly polarization wave having a second rotation reverse to said first rotation, on the basis of said starting modulation signal and said second carrier, said sub modulation portion being not supplied with power from said battery in a normal state, said main unit initiating communication by transmitting said starting circularly polarizaiton wave to said sub unit, said sub demodulation portion detecting said starting circularly polarization wave and triggering said sub modulation portion in response to a reception of said starting circularly polarization portion.
Claim 14
Dependent Claim
33 words
A radio frequency identification system according to claim 12, wherein said power supplied from said battery to said sub modulation portion is stopped after completion of a data transmission from said sub unit.
Claim 15
Dependent Claim
80 words
A radio frequency identification system according to claim 13, wherein said sub unit comprises a data processing portion (200), operatively connected to said sub demodulation portion and said sub modulation portion, for receiving said first transmission data (D1t) and sending said second transmission data (D2t), said data processing portion being supplied with power from said battery when said stating circularly polarization wave is received, and being not supplied with power after completion of said data transmission from said sub unit.
Claim 16
Dependent Claim
18 words
A radio frequency identification system according to claim 12, wherein said second transmission data comprises an identification code.
Claim 17
Dependent Claim
32 words
A radio frequency identification system according to claim 15, wherein said sub unit is mounted on a moving object, and transmits an identification code of said object which is previously stored therein.
Claim 18
Dependent Claim
87 words
A radio frequency identification system according to claim 1, wherein said main modem portion comprises a signal transfer means (5), a first detection and phase-shift means (6), a second detection and phase-shift means (7), and a signal adding means (10) for adding signals from said first and second detection and phase-shift means, said first and second detection and phase-shift means being connected to said signal transfer means, and spaced at (λg/8)n, where λg is an effective wave length of said carrier, and n is an odd integer.
Claim 19
Dependent Claim
28 words
A radio frequency identification system according to claim 1, wherein said sub unit is mounted on a moving object, and said main unit is installed a fix portion.
Claim 20
Dependent Claim
154 words
A radio frequency identification system comprising: a main unit including a main modulation and demodulation (modem) portion (11, 12), a main transmission portion (21) and a main reception portion (22); a sub unit, radio communicatable with said main unit through a radio-communication channel, including a sub reception portion (31), a sub modem portion (4), a sub transmission portion (32), and a small size battery supplying to said sub reception portion, said modem and said transmission portion, said main modem portion comprising a signal transfer means (5), a first detection and phase-shift means (6), a second detection and phase-shift means (7), and a signal adding means (10) for adding signal from said first and second detection and phase-shift means, said first and second detection and phase-shift means being connected to said signal transfer means, and spaced at (λg/8)n, where λg is an effective wave length of a reception signal, and n is an odd integer.
Claim 21
Dependent Claim
154 words
A radio frequency identification system comprising: a main unit including a main modulation and demodulation (modem) portion (11, 12), a main transmission portion (21) and a main reception portion (22); a sub unit, radio communicatable with said main unit through a radio-communication channel, including a sub reception portion (31), a sub modem portion (4), a sub transmission portion (32), and a small size battery supplying to said sub reception portion, said modem and said transmission portion, said main modem portion comprising a signal transfer means (5), a first detection and phase-shift means (6), a second detection and phase-shift means (7), and a signal adding means (10) for adding signal from said first and second detection and phase-shift means, said first and second detection and phase-shift means being connected to said signal transfer means, and spaced at (λg/8)n, where λg is an effective wave length of a reception signal, and n is an odd integer.
References Cited (Backward Citations)
No citation records indexed.
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