JPH0242376A - Body identification system - Google Patents

Abstract

PURPOSE:To discriminate whether or not there are beats generated by interference and to make a normal communication by intermitting oscillation of high frequency according to data to be sent and sending an electromagnetic wave which has a 1st plane of polarization to an ID unit. CONSTITUTION:A write/read control unit 3 intermits the oscillation of high frequency according to the data to be sent and sends the electromagnetic wave with the 1st plane of polarization to the ID unit 2. The ID unit 2 receives and demodulates the electromagnetic wave to identify the signal, writes necessary data in a memory 37, and reads necessary data out of a specific address of the memory 37 and supplies it to a reflection control part 32. The reflection control part 32 is connected to the antenna 31 of the ID unit 2 and varies the reflection coefficient of the antenna 31 to reflect the electromagnetic wave with the 1st plane of polarization as an electromagnetic wave with a 2nd plane of polarization. Consequently, the signal obtained at the antenna varies with the reflection factor on the side of the write/read control unit 3, so the data is received according to the variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an identification system for objects used in machine tools, parts in factories, product management, distribution systems, and the like.

[Prior art]

In order to mechanize the management of tools used in conventional machine tools and the identification of parts and products on assembly lines in factories, it is necessary to have a system that can identify and manage various items such as tool parts and products. Become.

Conventional management systems of this type include a method of attaching a label consisting of a barcode or the like to the object to be detected, and a method of attaching a group of magnets that represent data in binary values to an object for identification. A management system is known that retains data by inverting it. However, such a management system has problems in that it takes time to rewrite data, the reliability of the data is low, and the amount of information that can be held is small. Therefore, the applicant installed an ID unit with a memory in the object to be identified, modulated electromagnetic waves with transmitted data, and transmitted it to the ID unit.When receiving data, the applicant changes the reflection level of the transmitted signal to transmit data between the ID unit and the ID unit. We are proposing a device that retains necessary data in memory by doing this (unpublished).

[Problem to be solved by the invention]

However, according to such a conventional identification system, the reception efficiency of the reflected signal from the ID unit deteriorates as the distance increases, and it is necessary to receive the signal with extremely high sensitivity within the head section. Therefore, if a plurality of head sections are provided in parallel, interference may occur during reception due to electromagnetic waves from adjacent head sections. Therefore, the difference in oscillation frequency becomes a beat, but if this beat is close to the frequency of the regular modulation signal, it becomes difficult to separate the beat from the signal sent from the ID unit, making it impossible to perform normal communication. there were.

The present invention has been made in view of these conventional problems, and its technical object is to determine the presence or absence of beats caused by interference to enable normal communication.

[Means to solve the problem]

The present invention is an object identification system comprising an ID unit attached to an object, and a write/read control unit that writes data to and reads data from the ID unit, the ID unit having a first polarization plane. an antenna that receives electromagnetic waves of a predetermined frequency and reflects electromagnetic waves of a second polarization plane different from the first polarization plane; and a reflector that is connected to the antenna and changes its reflectance based on the signal to be transmitted. A control unit, a data demodulating means for demodulating the electromagnetic wave signal received by the antenna, a memory for storing the transmitted data, and controlling writing of data to the memory and reading of data based on the demodulated signal. The write/read control unit also includes a memory control means for supplying the read signal to the reflection control unit, and the write/read control unit includes an oscillator whose oscillation frequency is changed by a frequency shift signal;
an antenna that transmits the oscillation output of the oscillator as electromagnetic waves in a first polarization plane and receives reflected waves in a second polarization plane;
A data transmission means that intermittents the oscillation of the oscillator based on the data to be transmitted and obtains the original signal by demodulating the reflected wave obtained from the antenna, and an oscillation output connected between the output end of the oscillator and the antenna. a switch circuit that controls the supply to the antenna; and a frequency control means that determines the presence or absence of interference based on the received signal obtained from the data transmission means when the switch circuit is open, and changes the oscillation frequency of the oscillator based on the determined output. It is characterized by having the following.

[Effect]

According to the present invention having such characteristics, the write/read control unit intermittents high-frequency oscillation based on the data to be transmitted, and IDs the electromagnetic waves of the first polarization plane from the antenna.
I am trying to transmit it to the unit. The ID unit receives and demodulates the electromagnetic waves to identify the signal and writes necessary data into the memory, or reads the necessary data from a predetermined address in the memory and provides it to the reflection control section.

The reflection control section is connected to the antenna of the ID unit and changes the reflection coefficient of the antenna, and reflects the received electromagnetic waves of the first polarization plane as electromagnetic waves of the second polarization plane. In this case, the signal obtained by the antenna on the write/read control unit side changes as the reflectance changes, and data is received based on the change.

At the start of data communication, the switch circuit is opened so that no signal is received from a normal ID unit. In this state, the presence or absence of interference with other write/read control units is checked depending on whether a received signal is obtained from the data transmission means, and if there is interference, the oscillation frequency of the oscillator is changed to ensure that there is no interference. It allows data transmission to take place.

〔Effect of the invention〕

Therefore, according to the present invention, when a plurality of write/read control units coexist and cause interference with each other, the oscillators of the write/read control units are activated until mutual interference is eliminated before data communication is performed. The oscillation frequency is changed.Therefore, even when there are multiple write/read control units, data communication can be performed without mutual interference, and the reliability of data transmission can be improved. It will be done.

[Explanation of Examples]

FIG. 1 is a block diagram showing the structure of an object identification system according to an embodiment of the present invention. In this figure, the object identification system includes an ID unit 2 that is directly attached to an object 1 such as a tool, part, or product to be identified, and a write/read control unit 3 that writes and reads data to and from the ID unit 2. There is. The write/read control unit 3 is provided in a position close to the write/read control device main body 4 and the ID unit 2, and includes a head section 5 for writing and reading data to and from the ID unit 2. The ID unit 2 and the write/read control unit 3 constitute an object identification system. The write/read control unit 3 is connected to, for example, a higher-level control device 6, and configured to write and read data from the higher-level control device 6 to the ID unit 2 via the write/read control unit 3. There is.

Now, the write/read control unit 3, as shown in the detailed block diagram in FIG.
1, a memory 12 for holding the system program and data therein, and an S/P converter 13 for transmitting serial data to the read/write head 5 and converting the serial data into parallel signals. The write/read control unit 3 also has an external interface 14 and an MPUI that interface with the upper control device 6.
It has an A/D converter 15 which is an output means for I.

On the other hand, the read/write head 5 has a modulation circuit 21 to which a serial signal is applied from the S/P converter 13. The modulation circuit 21 performs FSK modulation on the applied NRZ serial signal, and for example, at logic "0", the frequency is 50KHz.
, when the logic is "1", a 30 KHz pulse signal is output. The output of the modulation circuit 21 is given to the oscillator 22 as a control signal. The oscillator 22 is, for example, a Hartley type microwave oscillator having a transistor Tri and microstrip lines AC, as shown in detail in FIG. This oscillator generates intermittent high frequency waves, for example, 2.45 GHz microwaves, based on the FSK signal. Further, a frequency shift signal is applied to the variable capacitance diode D1 of the oscillator 22, so that the oscillation frequency can be changed by, for example, several MHz. Now, the output of this oscillator 22 is given to an antenna 24 via a switch circuit 23 and also directly to a mixer circuit 25.

FIG. 4 is a perspective view showing this antenna 24.

The antenna 24 is constituted by, for example, a two-terminal drive type microstrip antenna, one terminal 24-T of which is connected to the switch circuit 23 and outputs horizontally polarized electromagnetic waves by supplying microwaves. Also, vertically polarized electromagnetic waves are received from this antenna and sent to the other receiving terminal 2.
4-R and the received signal is given to the mixer circuit 25. Now, it is assumed that the switching signal for the switch circuit 23 and the frequency shift signal for the oscillator 22 are provided directly from the MPU II of the write/read control device main body 4 or via the A/D converter 15. The mixer circuit 25 is the oscillator 22
A part of the oscillation output of the antenna 24 is mixed with a vertically polarized wave component received by the antenna 24, and the output thereof is given to the detection circuit 26. The detection circuit 26 removes the microwave carrier from the mixed output to obtain a transmitted signal, and the output thereof is given to the FSX demodulation circuit 27. F
The SK demodulation circuit 27 demodulates the FSK modulated signal and outputs the original NRZ binary signal, and its output is given to the S/P converter 13 of the write/read control device main body 3. . Here, the modulation circuit 21. Mixer circuit 25. The detection circuit 26 and the FSX demodulation circuit 27 constitute a data transmission means that intermittents the oscillation of the oscillator based on the data to be transmitted, and also demodulates the reflected wave obtained from the antenna to obtain the original signal. The MPU II and the A/D converter 15 constitute a frequency control means that determines interference based on the presence or absence of the received signal when the switch circuit 23 is turned off, and changes the oscillation frequency of the oscillator 22 based on the determined output.

Next, FIG. 5 is a block diagram showing the detailed configuration of the ID unit 2. As shown in FIG. The antenna 31 of the ID unit 2 has a reflection antenna 31a for both transmission and reception and a reception-only antenna 31b, as shown in detail in FIG. The reflection antenna 31a for both transmission and reception is a two-terminal drive type microstrip antenna, and has reception terminals 31a-R and transmission terminals 31a-T.
are connected to the reflection control section 32, respectively. The reflection control unit 32 includes a distributed constant circuit configured in a lattice shape having a length of 1/8λ with respect to the wavelength of the microwave, and a diode D2. D3, and its reflection coefficient is changed by turning on and off the diodes D2 and D3. Then, the microwave obtained from the receiving terminal 31a-R is modulated by the reflection coefficient determined by the reflection control unit 32, and is returned as a transmission wave to the transmitting terminal 31a-T of the antenna.
more re-radiated.

Further, the reception-only antenna 31b receives horizontally polarized signals, and its output is given to the detection circuit 33. Now, in FIG. 5, the detection circuit 33 outputs a low frequency FSK signal which is frequency-modulated from a microwave signal, and the output thereof is given to an FSK demodulation circuit 34. F
The SKi modulation circuit 34 demodulates the original NRZ serial signal from this signal, and its output is given to the S/P converter 35. The S/P converter 35 converts serial data into parallel data and provides it to the memory controller 36. The memory control unit 36 determines commands sent from the write/read control unit and controls writing of data to the memo 1J37 and reading of data from the memory 37. Further, the data and clock signal read out from the memory control section 36 are converted into serial data via the S/P converter 35 and provided to the modulation circuit 38. Modulation circuit 3
Reference numeral 8 denotes an FSK modulation circuit that outputs signals of 30 KHz and 50 KHz in response to logic "1" and "0" of the serial signal, respectively, and its output is given to the reflected wave control section 32. The reflection control section 32 includes a pair of diodes D2. The reflection coefficient is changed by turning D3 on and off. Depending on the presence or absence of this reflected wave, a signal read from the memory 37 is transmitted to the write/read control unit 3 side.

Next, the operation of this embodiment will be explained with reference to time charts and flowcharts. When the power is turned on to the write/read control unit 3, first in step 41, the switch circuit 23 is turned off (time 1+) to check for interference, as shown in the flowchart of FIG. 6 and the waveform diagram in FIG. 7 (b3). conduct.

In this case, since the serial signal is not given to the modulation circuit 21 via the S/P converter 13, the oscillator 23 is
), a microwave with a constant frequency fa is oscillated. If the switch circuit 23 is turned off here, the oscillation output is not given to the antenna 24 but only to the mixer circuit 25. In this state, even if the object 1 having the ID unit 2 is nearby, the antenna 24 does not output microwaves, so the antenna 24 receives nothing and the detection circuit 26 does not receive any signal. However, if another head section is in close proximity to the head section 5 and the microwave is similarly output from the head section 5, there is a possibility that interference will occur.

At this time, a signal of a certain level will be received by the antenna 24, and the difference between the microwave frequencies fb and fa of the other head sections 5 will be equal to the modulation frequency, for example, 3.
If the frequency is in the vicinity of 0KHz to 50KHz, Fig. 8 (b
There is a possibility that mutual interference may occur as shown in 1. In such a case, the detection circuit 26 outputs a low frequency signal, which is demodulated by the FSX demodulation circuit 27, as shown in FIG. 8(C). The demodulated signal is sent to the S/P converter 13
It is given to MPU11 via. When the switch circuit 23 is off, the antenna 24 does not send out microwaves, so no signal is received; however, in this state, the S/P converter 1
If a signal is transmitted from 3 to MPUII, interference has occurred. Therefore, the MPU II proceeds from steps 42 to 43, and if any signal is applied and an interference condition has occurred, the MPU II proceeds to step 44, and changes the frequency shift signal by one step. In this case, for example, as shown in FIG. 7(d), the frequency shift signal is raised by one step and changed stepwise.

Then, a frequency shift signal is transmitted to the oscillator 22 via the A/D converter 15, and the oscillation frequency fa is slightly shifted. Thereafter, the process returns to step 42 to check the interference state and check whether interference still occurs after the frequency shift. If the interference state has not ended as shown at time t2 in FIG. 7, the frequency shift signal is changed by one step again, and the end of the interference state is awaited. Assuming that the interference has ended as shown in FIG. 7(C) by changing the frequency shift signal at time t, the process proceeds from step 43 to step 45, where the switch circuit 23 is turned on. In this way, the microwave signal of the oscillator 22 is given to the antenna 24 and mixer circuit 25 at the same time.

Now, when transmitting data from the write/read control unit 3 to the ID unit 2, first turn on the switch circuit 23, and send the signal to be sent from the MPU II to the ID unit 2 to the S/P converter 13 in parallel data. give. The S/P converter 13 converts this signal into serial data and provides it to the modulation circuit 21. The modulation circuit 21 has its logic rlJ and r
Corresponding to OJ, signals of 30 KHz and 50 KHz are outputted and applied to the oscillator 22, respectively. Therefore, a microwave signal whose oscillation is intermittent as shown in FIG. 8(d) is obtained. This signal is then given to the antenna 24 via the switch circuit 23 and output as a horizontally polarized electromagnetic wave. When the ID unit 2 approaches, this signal is received by the antenna 31 of the ID unit 2 and given to the reflection control section 32 and the detection circuit 33. The detection circuit 33 removes the microwave component from this signal and
Signals of 0 KHz and 50 KHz are output, and the original NRZ signal is extracted by the FSX demodulation circuit 34 as shown in FIGS. 8(e) and (f). And this signal is S/
It is converted into parallel data by the P converter 35 and provided to the memory control section 36. The memory control unit 36 decodes the command in this signal and, if it is data, writes the data to a designated address.

Further, when transmitting data from the ID unit 2 to the write/read control unit 3, the head unit 5 causes the oscillator 22 to continuously oscillate to transmit horizontally polarized microwaves. On the other hand, the reflection antenna 31a of the antenna 31 receives this carrier signal and obtains a continuous microwave signal from the reception terminal 31a-R. The memory control unit 36 converts the data read from the memory 37 into serial data via the S/P converter 35, and converts the data into serial data corresponding to the logic levels rlJ and 'rOJ.
F so that the clock signal is 0KHz, 50KHz.
The signal is subjected to SK modulation and is provided to the reflection control section 32. Then, the diode D2 of the reflection control section 32. D3 is intermittent, the reflectance changes, and vertically polarized reflected waves corresponding to the 30 KHz and 50 KHz signals are transmitted from the antenna 31. This signal is transmitted to the antenna 2 of the head section 5.
4, and is applied to the mixer circuit 25 from its receiving terminal 24-R.

Since the microwave from the oscillator 22 is simultaneously applied to the mixer circuit 25, it is mixed with this signal to demodulate the original FSX signal. Further, by demodulating this signal using the FSK demodulation circuit 27, an NRZ signal can be obtained. In this way, data transmission is performed between the ID unit 2 and the write/read control unit 3. When starting data communication again, the presence or absence of interference with adjacent write/read control units is similarly checked in steps 41 to 44, and if there is mutual interference, the carrier frequency is changed to prevent interference. We are trying to prevent this from happening. In this way, mutual interference can be eliminated even when a large number of write/read control units coexist, and the reliability of data communication can be increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall structure of an object identification system according to an embodiment of the present invention, FIG. 2 is a block diagram showing the structure of a write/read control unit, and FIG. 3 is a circuit showing the structure of its oscillator. 4 is a schematic diagram showing the configuration of the antenna, FIG. 5 is a block diagram showing the configuration of the ID unit, and FIG.
The figure is a flowchart showing the operation for determining the presence or absence of interference, FIG. 7 is a time chart during mutual interference, and FIG. 8 is a waveform diagram of each part during data transmission. 1-...-object 2--4D unit 3...
−・・−Write/read control unit) 4−・−Write/
Readout control device main body 5.-----1--Head section
11-----'-M P U13.35-...-3/
P converter 15・---A/D converter
21.38---Modulation circuit 22---Oscillator 23-----Switch circuit 24.3
1-・-・-antenna 25-・-・mixer circuit
26゜33−・−・−・−Detection circuit 27.34−・
------F S K demodulation circuit 36---------
Memory control unit 37-・------Memory patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (and one other person) Figure 3 Figure 4 Figure Figure (d, 5s*a

Claims (1)

[Claims] (1) An object identification system comprising an ID unit attached to an object, and a write/read control unit that writes data to and reads data from the ID unit, wherein the ID unit has a first bias. an antenna that receives electromagnetic waves of a predetermined frequency on a wave surface and reflects electromagnetic waves of a second polarization plane different from the first polarization plane; and an antenna that is connected to the antenna and changes its reflectance based on a signal to be transmitted. a reflection control unit that demodulates the electromagnetic wave signal received by the antenna; a memory that stores the transmitted data; and a reflection control unit that demodulates the electromagnetic wave signal received by the antenna. and a memory control means for controlling reading of the signal and supplying the read signal to the reflection control section, and the write/read control unit includes: an oscillator whose oscillation frequency is changed by a frequency shift signal; , an antenna that transmits the oscillation output of the oscillator as an electromagnetic wave of the first polarization plane and receives a reflected wave of the second polarization plane; and an antenna that intermittents the oscillation of the oscillator based on the data to be transmitted; a data transmission means for obtaining an original signal by demodulating a reflected wave obtained from the antenna; a switch circuit connected between the output end of the oscillator and the antenna to control supply of oscillation output to the antenna; It is characterized by comprising a frequency control means that determines the presence or absence of interference based on the received signal obtained from the data transmission means when the switch circuit is opened, and changes the oscillation frequency of the oscillator based on the determined output. Object identification system.