JP4223991B2 - Wireless communication apparatus and printer - Google Patents

Description

  The present invention relates to a wireless communication device that performs wireless communication with an RF (Radio Frequency) tag and a printer including the wireless communication device.

  Conventionally, there are wireless communication devices such as an RF tag reader / writer and an RFID reader that perform wireless communication with an RF tag by electromagnetic waves radiated from an antenna.

  Such a wireless communication device employs a frequency hopping method that outputs an electromagnetic wave while changing the frequency every certain time within a certain frequency band without fixing the frequency of the radiating electromagnetic wave to one. There are some (for example, Patent Documents 1 and 2). In such a frequency hopping method, since the frequency of the electromagnetic wave is changed one after another, even when noise occurs at a specific frequency, the frequency is changed to a different frequency every certain time, so that normal communication is possible.

JP 2003-110458 A JP 2003-8590 A

  FIG. 6 is an explanatory diagram for explaining problems in the conventional frequency hopping, and the graph in the figure shows the frequency characteristics of the antenna. An antenna has a frequency characteristic in which a certain frequency has a gain peak. However, when designing a small antenna in a wireless communication apparatus such as a printer built-in, there is a frequency band in which the antenna gain can be sufficiently obtained due to size restrictions. It may become narrower. For example, as shown in FIG. 6, a phenomenon occurs in which the frequency band b in which the antenna gain is sufficiently obtained becomes smaller than the hopping frequency band a that is a frequency band used for frequency hopping. Further, the frequency characteristics of antennas vary among individuals even if the antennas are of the same type, and the frequency of the peak gain may be different for each antenna. FIG. 6 shows the frequency characteristics of the antenna A obtained when the gain peak is lower in frequency and the frequency characteristics of the antenna B obtained when the gain peak is higher in frequency.

  However, in the same type of product using antennas having different frequency characteristics between individuals as described above, electromagnetic waves are emitted by frequency hopping using the same method, resulting in variations in wireless communication performance between products. There is a possibility that a product with low communication performance will be manufactured.

  An object of the present invention is to obtain a wireless communication apparatus capable of considering antenna characteristics.

  The present invention generates a frequency hopping pattern corresponding to the frequency characteristic data of the antenna stored in the storage unit, the storage unit storing the frequency characteristic data of the antenna, and based on the generated frequency hopping pattern And means for radiating electromagnetic waves from the antenna.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communication apparatus which can consider the characteristic of an antenna can be obtained.

  A first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a label printer 1 which is a printer according to the present embodiment, and FIG. 2 is a longitudinal side view showing the label paper 3 in a drawn state. The label printer 1 of the present embodiment uses label paper 3 as paper. The label paper 3 has a structure in which a plurality of labels 3b are affixed to a long mount 3a at predetermined intervals and held in a roll shape. An RF (Radio Frequency) tag 4 is embedded in each label 3b. Such a label sheet 3 is held by the sheet holding unit 5 so as to be freely drawn out. The label printer 1 of the present embodiment has a structure in which the label paper 3 pulled out from the paper holding unit 5 is conveyed to the printing unit 6 to print on the label 3b, and the printed label 3b is issued from the label issuing port 7. is there. Prior to printing, data is read / written wirelessly from / to the RF tag 4 embedded in the label 3b by the RF tag reader / writer 8 serving as a wireless communication device on the upstream side of the printing unit 6. The RF tag reader / writer 8 is located below the label paper 3. As described above, the label printer 1 has a configuration using RFID (Radio Frequency Identification) in which the RF tag reader / writer 8 reads and writes the RF tag 4.

  The printing unit 6 includes a thermal head 9 and a platen 10 disposed to face the thermal head 9. In the printing unit 6, the label paper 3 is sandwiched between the thermal head 9 and the platen 10, and the platen 10 is rotated by a drive motor M 1 (see FIG. 3) to pull out and convey the label paper 3 from the paper holding unit 5. That is, the printing unit 6 also functions as a transport unit that transports the label paper 3. In the course of transporting the label paper 3, the thermal head 9 prints predetermined items on the label 3 b of the label paper 3. Further, as a printing method by the thermal head 9, a thermal transfer method is adopted. For this purpose, the label printer 1 of the present embodiment includes an ink ribbon supply unit 11, and the ink ribbon supply unit 11 guides and conveys the ink ribbon 12 between the label paper 3 and the thermal head 9. Such an ink ribbon supply unit 11 conveys the ink ribbon 12 by winding the ink ribbon 12 held on the support shaft 13 by a winding shaft 14 that is rotationally driven by a drive motor M2 (see FIG. 3). It has become.

  The label printer 1 is provided with sensors such as a label detection sensor 15. The label detection sensor 15 is a sensor that detects the label 13b. Further, the label printer 1 is provided with an operation unit 16 that receives an operation of the operator. The operation unit 16 includes an LCD (Liquid Crystal Display) 17 (see FIG. 3) and various operation keys 18 (see FIG. 3).

  FIG. 3 is a block diagram showing an electrical system of the label printer 1. The label printer 1 includes a main control unit 20. The main control unit 20 controls driving of each unit provided in the label printer 1. In such a main control unit 20, a ROM (Read Only Memory) 23 and a RAM (Read Only Memory) 24 are connected to a CPU (Central Processing Unit) 21 that centrally controls each unit via a bus line 22. Configured. The ROM 23 is a memory that stores in advance fixed data such as a computer program. The RAM 24 is a memory that stores various data in a rewritable manner, and functions as a work area, an image memory, and the like. A tag RF tag reader / writer 8, a thermal head 9, drive motors M1 and M2, a label detection sensor 15, an LCD 17, an operation key 18 and the like are connected to the main control unit 20 via a bus line 22. The drive control of each part by the control part 20 is possible.

  In addition, a data communication unit 25 is connected to the main control unit 20 via a bus line 22. The data communication unit 25 transmits / receives data to / from a host machine that is an external device.

  The tag RF tag reader / writer 8 connected to the main control unit 20 will be described. The RF tag reader / writer 8 includes a control unit 31 and a wireless communication unit 32 that has an antenna 38 and is controlled by the control unit 31. The control unit 31 is configured by connecting a CPU 35 to a ROM 35 that stores a computer printer, a RAM 36 that is a storage unit, and a data communication unit 37 via a bus line 34. The RAM 36 stores in advance a frequency x at which the gain, which is a prescribed characteristic of the antenna 38, is highest. The frequency x at which the gain of the antenna 38 becomes the highest is a value obtained by measuring the frequency characteristics of the antenna 38 with a known frequency measuring device. The RAM 36 is backed up by a battery (not shown).

  The data communication unit 37 is connected to the main control unit 20 via the bus line 22 and performs data communication with the main control unit 20. The wireless communication unit 32 includes an antenna 38 and a wireless circuit unit 39 that transmits and receives electromagnetic waves from the antenna 38, and the wireless circuit unit 39 is connected to the control unit 31 via the bus line 34. The RF tag reader / writer 8 radiates electromagnetic waves from the antenna 38 toward the RF tag 4 to read / write data from / to the RF tag 4 wirelessly. Various methods such as an electrostatic coupling method, an electromagnetic coupling method, an electromagnetic induction method, and a microwave method can be employed as a read / write method by wireless communication with respect to the RF tag reader / writer 8.

  Here, the RF tag 4 to be read / written by the RF tag reader / writer 8 includes an IC chip and an antenna (both not shown) composed of a CPU and an EEPROM (Electrically Erasable Programmable Read Only Memory) which is a nonvolatile memory. The radio frequency tag reader / writer 8 is configured to be capable of transmitting and receiving data wirelessly. The RF tag 4 is a non-power source type that is driven by electric power supplied from the RF tag reader / writer 8 by electromagnetic waves.

  Next, various processes executed by the CPU 21 constituting the main control unit 20 of the label printer 1 and the CPU 33 constituting the control unit 31 of the RF tag reader / writer 8 according to the computer program will be described together with the operations of the respective units.

  The printing process will be briefly described. When the CPU 21 receives a print command from the host machine or receives a print command from the operation unit 16 by an operator's operation, the CPU 21 drives the drive motors M1 and M2 and the thermal head 9 to perform a print operation on the label 3b. Let it run. Prior to this printing operation, a data read / write operation is performed on the RF tag 4 embedded in the label 3b. The label 3b when the read / write operation is performed on the RF tag 4 is positioned at a predetermined position above the RF tag reader / writer 8 and stopped. This position control can be performed using the label detection of the label detection sensor 15.

  Data read / write processing with respect to the RF tag 4 of the RF tag reader / writer 8 will be described. In the read / write processing, the CPU 33 of the RF tag reader / writer 8 generates a frequency hopping pattern corresponding to the frequency x with the highest gain of the antenna 38 stored in the RAM 36, and based on the generated frequency hopping pattern, the wireless circuit unit 39 is driven and electromagnetic waves are radiated from the antenna 38 while the radio circuit unit 39 hops the frequency. Thereby, reading / writing of the data with respect to RF tag 4 is performed.

  FIG. 4 is an explanatory diagram for explaining a frequency hopping pattern. The graph of FIG. 4 shows the frequency characteristics of the antenna 38. The generated frequency hopping pattern will be described. First, a hopping frequency band a that is a frequency band used for frequency hopping is set in advance. In the frequency hopping pattern, the frequency x at which the gain of the antenna 38 becomes the highest is used at the beginning of hopping, and thereafter, the frequency is randomly changed in a hopping frequency band a using a random number at regular intervals. It is a pattern. Here, the antenna 38 is designed so that the frequency x at which the gain of the antenna 38 manufactured within the manufacturing allowable error range becomes the highest is included in the hopping frequency band a. If the frequency x at which the gain of the antenna 38 is highest exists in a certain band, a certain frequency may be selected from the band.

  In such a configuration, the frequency hopping pattern is generated according to the frequency x at which the gain of the antenna 38, which is the frequency characteristic data of the antenna 38 stored in the RAM 36, becomes the highest. Is considered. The frequency characteristic of the antenna 38 stored in the RAM 36 as the storage unit is a frequency x at which the gain, which is a specified characteristic of the antenna 38, is the highest, and the frequency x at which the gain of the antenna 38 is the highest is hopped. Since the electromagnetic wave having the frequency x that maximizes the gain of the antenna 38 is radiated from the antenna 38 to the RF tag 4 at the beginning of hopping when reading and writing data to and from the RF tag 4 at the beginning, the antenna 38 is manufactured. Regardless of variations, reading and writing with respect to the RF tag 4 can be performed reliably and without taking time.

  Next, a second embodiment of the present invention will be described with reference to FIG. The description of the same parts as those of the above-described embodiment is omitted, and the same reference numerals are also used. FIG. 5 is an explanatory diagram for explaining a hopping pattern. The graph of FIG. 5 shows the frequency characteristics of the antenna 38.

  This embodiment is different from the first embodiment in the frequency hopping pattern generated when the RF tag reader / writer 8 reads / writes from / to the RF tag 4. In the present embodiment, a specified frequency band centered on the frequency x at which the gain, which is the specified characteristic of the antenna 38, is the highest is used for frequency hopping. Then, the frequency is randomly changed in the hopping frequency band a using a random number at regular intervals. As a result, a portion with a high gain (for example, a frequency band b where the gain of the antenna 38 is sufficiently obtained) enters the hopping frequency band a more reliably than a portion with a low gain. Conventionally, as in the antenna B of FIG. 6, a part of the frequency band b where the gain of the antenna B is sufficiently obtained is outside the hopping frequency band a, and frequencies other than the frequency band b where the gain of the antenna B can be sufficiently obtained. May be within the hopping frequency band a, but this does not occur in the present embodiment. Thereby, the performance of the antenna 38 can be sufficiently exhibited.

  In the above embodiment, the example of the RF tag reader / writer 8 has been described as the wireless communication device, but the present invention is not limited to this. The wireless communication device may be an RFID writer.

1 is a schematic diagram illustrating a label printer according to a first embodiment of the present invention. It is a vertical side view which shows the label paper of the state pulled out. It is a block diagram which shows the electrical equipment system of a label printer. It is explanatory drawing for demonstrating a frequency hopping pattern. It is explanatory drawing for demonstrating the frequency hopping pattern of the 2nd Embodiment of this invention. It is explanatory drawing for demonstrating the problem in the conventional frequency hopping.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Label printer (printer), 4 ... RF tag, 8 ... RF tag reader / writer (wireless communication apparatus), 36 ... RAM (memory | storage part), 38 ... Antenna

Claims (4)

In a wireless communication device that radiates electromagnetic waves from an antenna and performs wireless communication with an RF tag,
A storage unit for storing frequency characteristic data of the antenna;
Means for generating a frequency hopping pattern corresponding to the frequency characteristic data of the antenna stored in the storage unit, and radiating electromagnetic waves from the antenna based on the generated frequency hopping pattern;
A wireless communication apparatus comprising: The frequency characteristic of the antenna stored in the storage unit is a frequency at which the specified characteristic of the antenna is highest,
2. The wireless communication apparatus according to claim 1, wherein the means uses a frequency at which a prescribed characteristic of the antenna becomes highest at the beginning of hopping. The frequency characteristic of the antenna stored in the storage unit is a frequency at which the specified characteristic of the antenna is highest,
2. The wireless communication apparatus according to claim 1, wherein said means uses a specified frequency band centered on a frequency at which a specified characteristic of the antenna is highest for frequency hopping. A printer comprising the wireless communication device according to any one of claims 1 to 3.

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