Wireless tag passing determination apparatus

1. A wireless tag passing determination apparatus comprising:

an antenna that provides a plurality of communicable regions and a communication disabled region, the communicable regions being arranged alternately with the communication disabled region, such that the plurality of communicable regions includes both sides of a passing determination point in a longitudinal direction of a passage in which passing of a wireless tag is determined;

a tag reader that determines whether to read a signal transmitted by the wireless tag, based on a signal representing electric wave transmitted by the wireless tag existing in the plurality of communicable regions and received by the antenna; and

a passing determination section that determines whether the wireless tag passes by the passing determination point on the passage, based on a pattern of presence or absence of reading in association with a lapse of time, the pattern of the presence or the absence of the reading being a pattern generated when the tag reader reads the signal transmitted by the wireless tag, the pattern of the presence or the absence of the reading including at least one result by the tag reader indicative of the absence of the reading and at least two results by the tag reader indicative of the presence of the reading,

wherein:

the communication disabled region is positioned between two of the communicable regions; and

the passing determination point is positioned between the two of the communicable regions on the passage.

2. The wireless tag passing determination apparatus according to claim 1 , wherein:

the antenna provides the plurality of communicable regions that is asymmetrical with respect to a center of the passing determination point in the longitudinal direction of the passage.

3. The wireless tag passing determination apparatus according to claim 1 , wherein:

the tag reader transmits a transmission wave to the plurality of communicable regions;

the tag reader acquires a signal representing a reception wave that is electric wave transmitted by the wireless tag in response to the transmission wave and received by the antenna in a case in which the wireless tag exists in the plurality of communicable regions, and determines whether to read the signal transmitted by the wireless tag;

the wireless tag passing determination apparatus further comprises

a phase calculation section that acquires the signal representing the reception wave and successively calculates a phase of the reception wave; and

the passing determination section generates the pattern of the presence or the absence of the reading without using a determination result as to whether the signal transmitted by the wireless tag is read, the determination result being obtained at a time the phase calculated by the phase calculation section is not changed from the phase calculated at a previous time.

4. The wireless tag passing determination apparatus according to claim 1 , wherein:

the passing determination section generates the pattern of presence or the absence of the reading in association with the lapse of time.

5. The wireless tag passing determination apparatus according to claim 4 , wherein:

the passing determination section stores a reference pattern showing results of the presence or the absence of the reading with the lapse of time when the wireless tag moves from end to end of the communicable regions; and

the passing determination section compares the pattern of presence or the absence of reading with the reference pattern so as to determine whether the wireless tag passes by the passing determination point.

6. The wireless tag passing determination apparatus according to claim 1 , wherein:

the pattern of the presence or absence of the reading includes only two symbols including

a first symbol indicative of a case where the reading has been performed, and

a second symbol indicative of a case where the reading has not been performed.

7. A wireless tag passing determination system comprising:

a passage where it is determined whether a wireless tag passes on; and

a wireless tag passing determination apparatus including

an antenna that provides a plurality of communicable regions and a communication disabled region, the communicable regions being arranged alternately with the communication disabled region, such that the plurality of communicable regions includes both sides of a passing determination point in a longitudinal direction of the passage,

a tag reader that determines whether to read a signal transmitted by the wireless tag, based on a signal representing electric wave transmitted by the wireless tag existing in the plurality of communicable regions and received by the antenna, and

a passing determination section that determines whether the wireless tag passes by the passing determination point on the passage, based on a pattern of presence or absence of reading in association with a lapse of time, the pattern of the presence or the absence of the reading being a pattern generated when the tag reader reads the signal transmitted by the wireless tag, the pattern of the presence or absence of the reading including at least one result by the tag reader indicative of the absence of the reading and at least two results by the tag reader indicative of the presence of the reading,

wherein:

the communication disabled region is positioned between two of the communicable regions; and

the passing determination point is positioned between the two of the communicable regions on the passage.

8. The wireless tag passing determination apparatus according to claim 7 , further comprising:

a reading determination section that generates and stores the pattern of the presence or the absence of the reading based on a determination result of the tag reader.

9. The wireless tag passing determination apparatus according to claim 8 , wherein:

the pattern includes two parts of the presence of the reading and one part of the absence of the reading; and

the one part of the absence of the reading is arranged between the two parts of the presence of the reading.

10. The wireless tag passing determination apparatus according to claim 6 , wherein the first symbol is a “1” and the second symbol is a “0.”