Data carrier system

• US 6,118,367 A
• Filed: 11/20/1997
• Issued: 09/12/2000
• Est. Priority Date: 11/29/1996
• Status: Expired due to Fees

• Current Assignee: Yoshikawa RF Systems Company Limited
• Original Assignee: Yoshikawa RF Systems Company Limited
• Inventors: Ishii, Eiichi
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Dalencourt, Yves
• Application Number:
  US08/975,197
• Time in Patent Office: 1,027 Days
• Field of Search: 340/825.54, 340/825.31, 340/10.1, 340/572.1, 340/572.5, 340/572.7, 343/895, 343/866, 343/867, 343/868, 343/844, 343/745, 343/748, 343/834, 343/839, 343/912, 343/913, 455/41, 455/120, 455/123, 455/125, 455/193.1, 455/121, 455/197.3, 334/63, 334/71, 342/51
• US Class Current: 340/10.1
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A data carrier system is provided including: a main apparatus including a first control unit for outputting a first signal and a first coil unit having at least a transmission coil for transmitting the first signal; a tuner circuit unit having a tuner circuit being tuned with the frequency of the first signal, the tuner circuit having a tuning coil disposed facing the transmission coil of the first coil unit; and a tag including a second coil unit having at least a reception coil and a second control unit for performing a predetermined control operation in accordance with the first signal transmitted from the main apparatus and received by the reception coil of the second coil unit.

Claims

1. A data carrier system comprising:

a main apparatus including first control means for outputting a first signal and first coil means having at least a transmission coil for transmitting the first signal;

tuner circuit means having a tuner circuit including a tuning coil disposed facing the transmission coil of said first coil means and [adapted to be] tuned with the frequency of the first signal; and

a tag including second coil means having at least a reception coil for receiving the first signal transmitted from said main apparatus and second control means for performing predetermined control operation in accordance with the received first signal, wherein said tag moves along a passage between the transmission coil of the main apparatus and said tuning coil of said tuner circuit means and wherein when the sizes of the transmission coil and tuning coil are represented by radii R and r of equivalent circular coils having the same areas as those of the transmission coil and the tuning coil, respectively, R is generally equal to r, and a distance D between said first coil means and said tuner circuit means satisfies the condition of 2R≦

D≦

3R.

2. A data carrier system according to claim 1, wherein the area of a coil surface of the tuning coil is almost equal to the area of a coil surface of the transmission coil of said first coil means.

3. A data carrier system according to claim 1, wherein said second control means of said tag includes means for generating a second signal in accordance with the received first signal, said second coil means of said tag includes a transmission coil for transmitting the second signal, and said first coil means of said main apparatus includes a reception coil for receiving the second signal transmitted from the transmission coil of said tag.

4. A data carrier system according to claim 3, wherein the reception and transmission coils of said second coil means of said tag are formed of a single common transmission/reception coil.

5. A data carrier system according to claim 4, wherein the reception and transmission coils of said first coil means of said main apparatus are formed of loop circular coils disposed concentrically, and a radius of the reception coil is larger than a radius of the transmission coil.

6. A data carrier system according to claim 5, further comprising:

second tuner circuit means having a tuner circuit being tuned with the frequency of the second signal transmitted from said tag, the tuner circuit including a second tuning coil of a loop circular shape disposed concentrically with the reception coil of said first coil means of said main apparatus and a second capacitor connected in parallel to the second tuning coil.

7. A data carrier system according to claim 6, wherein the second tuning coil has an inner area one-fourth of or smaller than an inner area of the reception coil of said first coil means, and larger than the inner area of each of the transmission and reception coils of said second coil means of said tag.

8. A data carrier system according to claim 1, wherein the transmission coil of said first coil means of said main apparatus is a circular coil, and the tuning coil of said tuner circuit means is a circular coil having the same radius as the circular coil of the transmission coil.

9. A data carrier system comprising:

a tag including first coil means having a transmission coil and a reception coil;

control means for performing control operations in accordance with a first signal received externally by the reception coil and generating at least a second signal; and

means for transmitting the second signal via the transmission coli;

a main apparatus including second coil means having a transmission coil of a loop circular shape and a reception coil of a loop circular shape disposed concentrically with the transmission coil, the transmission coil transmitting a signal to said tag through electromagnetic coupling with the reception coil of said first coil means of said tag, and the reception coil receiving a signal transmitted from said tag through electromagnetic coupling with the transmission coil of said first coil means of said tag; and

tuner circuit means having a tuner circuit including a tuning coil of a loop circular shape disposed concentrically with the reception coil of said second coil means and a tuning capacitor connected in parallel to the tuning coil,

wherein when the sizes of the transmission coil and tuning coil are represented by radii R and r of equivalent circular coils having the same areas as those of the transmission coil and tuning coil, respectively, R is generally equal to r, and a distance D between said first coil means and said tuner circuit means satisfies the condition of 2R≦

D≦

3R.

10. A data carrier system according to claim 9, wherein the tuning coil has a size larger than the reception coil of said second coil means of said main apparatus.

11. A data carrier system according to claim 9, wherein the transmission coil and the reception coil of said tag are formed of a single common transmission/reception coil.

12. A tag monitor for use with a data carrier system comprising:

a main apparatus including first control means for outputting a first signal and first coil means having at least a transmission coil for transmitting the first signal toward a tag to be monitored; and

tuner circuit means having a tuner circuit being tuned with the frequency of the first signal, said tuner circuit means being disposed spaced apart from said main apparatus by a predetermined distance, and the tuner circuit having a tuning coil disposed facing the transmission coil of said first coil means and a capacitor connected in parallel to the tuning coil, wherein when the sizes of the transmission coil of said first coil means and the tuning coil of said tuner circuit means are represented by radii R and r of equivalent circular coils having the same areas as those of the transmission coil and the tuning coil, respectively, and R is almost equal to r, a distance between said first coil means and said tuner circuit means satisfies the condition of 2R≦

D≦

3R.

13. A tag monitor according to claim 12, further comprising a passage provided between said main apparatus and said tuner circuit means for allowing the tag to be monitored to pass therethrough.

14. A tag monitor according to claim 12, wherein the size of a coil surface of the transmission coil of said first coil means is equal to the size of a coil surface of the tuning coil.

15. A tag monitor according to claim 12, wherein said first coil means of said main apparatus includes a reception coil for receiving a second signal transmitted from the tag to be monitored, and the transmission coil and the reception coil of said first coil means are both formed of a circular loop shaped and disposed concentrically.

16. A tag monitor according to claim 15, wherein said reception coil of said first coil means has a radius smaller than that of said transmission coil.