JPH09312598A - Noncontact communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of reverberation at a long distance in a noncontact communication equipment transmitting data by transmitting a high frequency signal by a write/read control unit and controlling reverberation during it. SOLUTION: A voltage monitoring part 50 monitoring voltage is provided in a data carrier 30. As a voltage level drops when the distance between the write/read control unit becomes long, the counting value of a counter 37 counting a carrier pulse is reduced. Thereby even when the start of counting by a counter is delayed at the time of long distance communication, the timing of counting up is not delayed and a shunt pulse is generated at a proper time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a physical distribution system for managing tools and products and a non-contact communication device used for identifying a human body.

[0002]

2. Description of the Related Art Conventionally, a system for identifying and managing various articles such as tools, parts and products in order to mechanize the management of tools of machine tools and the identification of parts and products in an assembly and conveyance line in a factory. Is required. Therefore, JP-A-1-151831
As shown in the item No., a memory unit (data carrier) having a memory is provided in the identification object, and necessary information is written in such a memory by data transmission from the outside, and the information is stored as necessary. There has been proposed a non-contact communication device adapted to read out.

Such a conventional non-contact communication device is shown in FIG.
As shown in FIG. 3, it is composed of a write / read control unit including an ID controller 1 and a read / write head 2 and a data carrier 3. The read / write head 2 intermittently oscillates at a constant frequency to transmit a signal to the data carrier 3 side. When receiving data, a signal with a constant duty ratio is sent to control reverberation by a resonance circuit in the data carrier. . In the read / write head 2, a resonance circuit determines the presence or absence of this reverberation and receives a signal.

In FIG. 7, the write / read control unit is I
It has a D controller 1 and a read / write head 2. The ID controller 1 has a transmission control circuit 11, a reference clock generation circuit 12, and a reception control circuit 13. The transmission control circuit 11 has first and second duty ratios corresponding to the transmission data signal when transmitting data from the read / write head 2 side to the data carrier 3, and a constant third duty ratio when receiving data, for example, It is intended to generate an intermittent constant frequency transmission signal having a duty ratio of 50%. The first duty ratio is, for example, 30%, the second
The duty ratio of is, for example, 70%. The read / write head 2 includes an oscillator circuit 15 and an oscillator circuit 15 as shown in the figure.
A coil L1 for transmission connected to is provided. The coil L1 is provided on the surface facing the data carrier 3. The oscillator circuit 15 is an oscillator circuit that oscillates at a constant frequency under the control of the transmission control circuit 11. Further, the receiving circuit is provided with a resonance circuit 16 including a coil L2 and a capacitor C1. The resonance circuit 16 is provided in parallel with an analog switch 17 which is opened / closed by a gate signal G1 from the reception control circuit 13. The output of the resonance circuit 16 is demodulated by the demodulation circuit 18 and given to the reception control circuit 13. Also, the receiving coil L2 is provided on the surface facing the data carrier similarly to the coil L1.

FIG. 8 is a block diagram showing the structure of a conventional data carrier 3. In the figure, the data carrier 3 has a resonance circuit 31. The resonance circuit 31 is the coil L3.
And a capacitor C2 connected in parallel with the coil L3. A full-wave rectification circuit 32 is connected to both ends of the resonance circuit 31. The full-wave rectification circuit 32 performs full-wave rectification on the obtained signal and supplies it to each part of the data carrier as the power supply V _DD via the power supply circuit 33.

A DEM extraction circuit 34 is connected to one end of the resonance circuit 31. The DEM extracting circuit 34 converts the carrier of the transmission signal into a square wave by half-wave rectifying and shaping the carrier of the transmission signal as a passing frequency, and its output is given to the demodulation circuit 35. Further, the integration comparator circuit 36 is connected to one end of the resonance circuit 31. The integration comparator circuit 36 performs envelope detection of the signal obtained in the resonance circuit 31, discriminates the power supply with a threshold value obtained by dividing the power supply, extracts the clock signal CKA, and outputs the output to the demodulation circuit 35. . When the data carrier receives a signal, the demodulation circuit 35 counts the number of carrier pulses extracted by the DEM extraction circuit 34 based on CKA, and determines either the H level or the L level depending on the duty ratio of intermittent transmission. To do. The signal thus demodulated is separated into a command and data by the memory control unit 38, necessary data is written in the memory 39, and the data is read from the memory 39. When the data carrier 3 transmits data, a signal having a constant duty ratio is transmitted from the read / write head. The counter 37 counts the DEM pulses at this time and outputs a timing signal to the shunt pulse generation circuit 40. The data read from the memory control unit 38 is converted into, for example, a serial bi-phase code and input to the shunt pulse generation circuit 40. Shunt pulse generation circuit 40
When a count-up timing signal is given from the counter 37, a shunt pulse is generated according to the biphase signal, and is input to the shunt circuit 41. The shunt circuit 41 has a pair of switching elements that ground both ends of the resonance circuit 31 based on a shunt pulse, and grounds both ends of the resonance circuit at the same time to stop reverberation in a short time.

Next, the waveform of each part of the read / write head and the data carrier will be described. FIG. 9 (a)-
(H) shows the waveform of each part of a to h of FIGS. FIG. 9A shows a transmission waveform transmitted from the transmission unit of the read / write head. When the signal of FIG. 9 (a) is received by an adjacent data carrier 3, its resonant circuit 3
The resonance waveform shown in FIG. This signal is integrated by the integration comparator circuit 36, and
It is converted into a clock signal CKA as shown in (c).
When the read / write head 2 receives a signal from the data carrier 3, a signal having a duty ratio of 50% is always transmitted as shown in FIG. The data carrier receives this signal, and the DEM extraction circuit 34 CK
The number of carrier pulses included in the signal in which A is at the H level is extracted and counted. Then, when the signal read from the memory control unit 38 and converted into the bi-phase code when the count value of the counter 37 reaches a predetermined number, for example 13, is at the L level, the shunt pulse generation circuit 40 causes the shunt pulse generation circuit 40 to generate a signal shown in FIG.
A shunt pulse is output as shown in. Both ends of the resonance circuit 31 are grounded by this shunt pulse.
The resonance waveform immediately stops as shown in (b). In the receiver of the read / write head 2, this signal is detected by the resonance circuit 16, and the analog switch 17 is opened by the gate signal G1 at the latter half timing while the transmission waveform is stopped, as shown in FIG. 9 (h). The signal from the data carrier 3 is received depending on the presence or absence of reverberation at this point.

[0008]

However, in the conventional data carrier 3, the Q of the coil L3 of the resonance circuit 31 is set high so that communication can be surely performed even if the data carrier 3 is located away from the read / write head 2. As a result, especially when the data carrier is distant, the rise of the resonance waveform is delayed as shown after time t _{3 in} FIGS.
The pulse detection and the DEM pulse counting start are delayed. Therefore, even when a shunt pulse is generated by the data to be transmitted, reverberation remains while the gate G of the read / write head is open, as shown in FIG. 9 (g) or (h). The graph shown in FIG. 4 (a) is a diagram showing the level while the gate of the read / write head is open with respect to the read / write head and the distance. Rises. Therefore, if the distance is long, H and L cannot be discriminated, a dead zone occurs, and there is a drawback that the H level may be erroneously detected even though it is at the L level.

The present invention has been made by paying attention to such a conventional problem, and is normal even when the data carrier is located at a position distant from the read / write head and erroneous detection may occur. The purpose is to enable data transmission from the data carrier to the read / write head.

[0010]

According to a first aspect of the present invention, there is provided a non-contact system comprising a data carrier and a write / read control unit for transmitting data to the data carrier and receiving the transmitted data. In the communication device, the write / read control unit includes a transmission control circuit that generates a signal having a constant duty ratio when receiving data, and a first coil provided on a surface facing the data carrier. An oscillation circuit that intermittently oscillates based on a transmission signal given by the transmission control circuit; and a second coil provided on a surface facing the data carrier, and a signal obtained by the second coil is waveform-shaped. A reception control circuit for reading data by shaping the data carrier, wherein the data carrier is a third coil provided so as to face the write / read control unit. A resonance circuit including the same, demodulation means for demodulating a signal based on the envelope signal and the carrier pulse of the resonance signal received by the resonance circuit, and counting the carrier pulses included in the resonance signal and outputting a count-up signal. A counter, a voltage monitoring unit that monitors the voltage level obtained from the resonance circuit, and decreases the count value that counts up the counter according to the decrease in the voltage level, a memory, and a data carrier at the time of data transmission. Reverberation control means for controlling the reverberation of the resonance circuit based on the data read from the memory based on the timing of counting up from the counter while the oscillation of the oscillation circuit is stopped. is there.

According to the first aspect of the present invention having such a feature, the data carrier is provided with the voltage monitoring means for monitoring the voltage level obtained from the resonance circuit. When the distance from the write / read control unit increases, the voltage level detected by the voltage monitoring means decreases. In this case, the timing for counting up is advanced by decreasing the predetermined count value of the counter. By doing so, the generation of the shunt pulse for controlling the reverberation can be accelerated, and the reverberation can be prevented from occurring on the write / read control unit side even when the reverberation is stopped.

The invention of claim 2 of the present application is a non-contact communication device comprising a data carrier and a write / read control unit for transmitting data to the data carrier and receiving the transmitted data. The write / read control unit includes a transmission control circuit that generates a signal with a constant duty ratio when receiving data, and a first coil provided on a surface facing the data carrier. An oscillation circuit that intermittently oscillates based on a given transmission signal, and a second circuit provided on a surface facing the data carrier.
A reception control circuit that reads data by waveform-shaping a signal obtained by the second coil.
And the data carrier includes a resonance circuit including a third coil provided facing the write / read control unit, and a comparator for discriminating a resonance signal received by the resonance circuit. A demodulation unit that demodulates a signal based on a carrier pulse and its envelope signal; a counter that counts carrier pulses obtained from a comparator of the demodulation unit and outputs a count-up signal at a predetermined count value; While monitoring the obtained voltage level and decreasing the threshold voltage of the comparator in accordance with the decrease in the voltage level, a memory, and while the oscillation of the oscillation circuit is stopped during the transmission of data from the data carrier. The resonance circuit is based on the data read from the memory based on the count-up timing from the counter. It is characterized in that it has a reverberation control means for controlling the reverberation, the.

According to the invention of claim 2 having such a feature, the data carrier is provided with the voltage monitoring means, and when the decrease of the voltage level is detected, the threshold voltage of the comparator is decreased. To count the carrier pulses obtained from the comparator and output a count-up signal,
If the threshold value of the comparator is lowered, the counting is started from the carrier pulse of a low level, and the timing of stopping the reverberation can be advanced. Therefore write /
It is possible to prevent the occurrence of reverberation on the receiving coil side of the read control unit.

[0014]

FIG. 2 is a block diagram showing an overall configuration of a write / read control unit according to an embodiment of the present invention. In this figure, the same parts as those of the above-described conventional example are denoted by the same reference numerals, and detailed description is omitted. Also in this embodiment, the configuration on the write / read control unit side is the same.
The controller 1 has a transmission control circuit 11, a reference clock generation circuit 12, and a reception control circuit 13. The transmission control circuit 11 moves from the read / write head 2 side to the data carrier 3
When transmitting data to 0, it has a first duty ratio and a second duty ratio corresponding to the transmission data, and when receiving the data, it transmits a transmission signal of a constant frequency which is intermittent with a constant third duty ratio, for example, a duty ratio of 50%. It occurs. The read / write head 2 has an oscillating circuit 15 as shown.
And a coil L1 for transmission connected to the oscillator circuit 15. The coil L1 is provided on the surface facing the data carrier. The oscillator circuit 15 is an oscillator circuit that oscillates at a constant frequency under the control of the transmission control circuit 11. Further, the receiving circuit is provided with a resonance circuit 16 including a coil L2 and a capacitor C1. The output of the resonance circuit 16 is demodulated by the demodulation circuit 18 when the analog switch 17 is off and given to the reception control circuit 13. The receiving coil L2 is also provided on the surface facing the data carrier 30, like the coil L1.

On the other hand, the data carrier 30 is used by being attached to, for example, an article to be identified, and holds data of the article. As shown in FIG. 1, the data carrier 30 includes a resonance circuit 31 and a full-wave rectification circuit 3 as in the conventional example.
2. The power supply circuit 33 and the DEM extraction circuit 34 are connected. Further, an integration comparator circuit 36 is connected to the resonance circuit 31, CKA is extracted, and a demodulation circuit 35 demodulates the received signal. The DEM extraction circuit 34, the demodulation circuit 35, and the integration comparator circuit 36 constitute demodulation means. In this embodiment, the power supply circuit 33 is provided with the voltage monitoring unit 50. The voltage monitoring unit 50 detects a signal corresponding to the distance to the object by the voltage output from the power supply circuit 33, and its output is the control unit 5.
Given to one. The control unit 51 is the memory control unit 3 of the conventional example.
In addition to the function of No. 8, it has a function of changing the count value of the counter 37 based on the monitoring signal from the voltage monitoring unit 50. The voltage monitoring unit 50 and the control unit 51 constitute a voltage monitoring unit that monitors the voltage level of the resonance circuit and decreases the count value that the counter counts up based on the decrease in the voltage level. Other configurations are the same as those of the above-described conventional example, and the output of the demodulation circuit 35 is given to the memory 39 via the control unit 51. The configurations of the memory 39, the shunt pulse generation circuit 40, and the shunt circuit 41 are similar to those of the conventional example. The control unit 51 converts the data read from the memory 39 into a biphase code and gives it to the shunt pulse generation circuit 40. The shunt pulse generation circuit 40 outputs a shunt signal in synchronization with the count-up output of the counter 37, and its output is the shunt circuit 41.
Given to. The shunt circuit 41 has a pair of switching elements that ground both ends of the resonance circuit 31 based on a shunt pulse, and grounds both ends of the resonance circuit at the same time to stop reverberation in a short time.
Here, the shunt pulse generation circuit 40 and the shunt circuit 4
Reference numeral 1 constitutes reverberation control means for controlling the reverberation of the resonance circuit 31.

Next, the operation of this embodiment will be described with reference to a time chart. FIGS. 3A to 3H are waveform charts showing the waveforms of the respective portions a to h in FIGS. 1 and 2. FIG. 3A shows a transmission waveform having a duty ratio of 50% which is oscillated by the oscillation circuit of the read / write head and is transmitted to the data carrier 30 side via the transmission coil L1. When the data carrier 30 is in a position where it can communicate with the read / write head 1, when this signal is received, FIG.
The resonance waveform shown in (b) is obtained. As in the conventional example, when the data carrier 30 approaches the read / write head 2, the fall of the resonance waveform is delayed as compared with the fall of the transmission waveform as shown in the above-mentioned time chart.

However, in this embodiment, the voltage monitoring unit 50 is provided on the output side of the power supply circuit 33. And the voltage monitoring unit 5
If the voltage input to 0 exceeds a predetermined value, the control unit 51 determines that the distance to the data carrier 30 is long.
The count value of the counter 37 connected to the resonance circuit 31 via is decreased. For example, the counter 37 in the normal case
When the count value of is 13 and the voltage level V _DD is low (V _DD <V _DDO ), and the data carrier 30 is far from the read / write head 2, the count value is changed to “12”. . In this way, the count-up pulse is output when the counter 37 counts "12", and the timing of the count-up output can be advanced.
Since the count value of the counter 30 is reduced by the output of the voltage monitoring unit 50 as described above, the count-up pulse is not delayed, and the generation of the shunt pulse is delayed almost unlike the conventional example as shown in FIG. 3 (f). Disappears. Therefore, as shown in FIG. 3G, in the read / write head, reverberation does not occur when the gate pulse G1 is released due to residual reverberation, and malfunction can be prevented.

FIG. 4A shows the level when the gate pulse G1 is opened when there is reverberation and when there is no reverberation with respect to the distance between the read / write head and the data carrier. Further, FIG. 4B shows the change of the voltage V _DD obtained in the power supply circuit 33 with respect to the distance and the count value of the counter 37. In this way, when the distance is equal to or greater than the predetermined value, the count value of the counter is increased, and when the distance is increased, the count value is decreased, so that there is no reverberation shown by the broken line in FIG. In this case, the output is prevented from rising and changes as shown by the solid line. Therefore, malfunction can be prevented in advance.

In the present embodiment, the count value of the counter is changed in two steps from 13 to 12 according to the output of the voltage monitoring section, but it goes without saying that it may be changed in a plurality of steps. Absent.

FIG. 5 is a block diagram showing the structure of the data carrier 30A according to the second embodiment of the present invention. In the present embodiment, the comparator circuit 61 that changes the threshold value based on the output of the voltage monitoring unit 50 is provided. One end of the resonance circuit is connected to D through the threshold value changing comparator circuit 61.
It is connected to the EM extraction circuit 34. In this case, the count value of the counter 37 is set to a constant value of "13", for example. The control unit 62 lowers the threshold value of the comparator circuit 61 when the voltage V _DD decreases due to the output from the voltage monitoring unit 50. The voltage monitoring unit 50 and the control unit 62 constitute a voltage monitoring unit that monitors the voltage level obtained from the resonance circuit and lowers the threshold voltage of the comparator according to the voltage drop. Other configurations are the same as those of the conventional example described above.

Next, the operation of this embodiment will be described with reference to the time chart of FIG. Also in this embodiment, the basic operation is the same as in the above-described conventional example and the first embodiment. In the present embodiment, when the data carrier 30A is separated from the read / write head 2 and the voltage level detected by the voltage monitoring circuit 50 becomes low, the threshold value of the comparator circuit 61 for extracting the DEM pulse is lowered to generate the DEM pulse. Extract. In this way, the start of counting DEM pulses is accelerated as shown in FIG. 6D, so that the generation of shunt pulses is not delayed. Therefore, FIG. 6 (h)
As shown in, there is no reverberation during the reception of the read / write head while the gate is open. Therefore, a communication error will not occur even at a long distance.

[0022]

As described in detail above, according to the inventions of claims 1 and 2 of the present application, when the Q of the resonance circuit of the data carrier is increased to enable data transmission over a long distance. Also, reliable data transmission can be performed without causing a malfunction of a communication error in a long distance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a data carrier according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a write / read control unit of the non-contact communication device according to the present embodiment.

FIG. 3 is a waveform diagram showing a waveform of each part of the non-contact communication device of this embodiment.

FIG. 4A is a sample hold level of the read / write head with respect to the distance between the read / write head and the data carrier of the present embodiment, and FIG. 4B is a graph showing changes in the voltage V _DD of the data carrier and the count value of the counter. Is.

FIG. 5 is a block diagram showing a configuration of a data carrier according to a second embodiment of the present invention.

FIG. 6 is a waveform diagram showing the operation of the data carrier according to the second embodiment.

FIG. 7 is a block diagram showing an overall configuration of a conventional non-contact communication device.

FIG. 8 is a block diagram showing an example of a conventional data carrier.

FIG. 9 is a waveform diagram showing a waveform of each part of a conventional non-contact communication device.

[Explanation of symbols]

 1 ID Controller 2 Read / Write Head 3, 30, 30A Data Carrier 11 Transmission Control Circuit 12 Reference Clock Generation Circuit 13 Reception Control Circuit 15 Oscillation Circuit 16, 31 Resonance Circuit 17, 35 Demodulation Circuit 34 DEM Extraction Circuit 36 Integral Comparator Circuit 37 Counter 38 Memory control unit 39 Memory 40 Shunt pulse generation circuit 41 Shunt circuit 50 Voltage monitoring unit 51, 62 Control unit 61 Threshold change comparator circuit

Claims (2)

[Claims] 1. A contactless communication device comprising: a data carrier; and a write / read control unit for transmitting data to the data carrier and receiving the transmitted data, wherein the write / read control unit. Has a transmission control circuit for generating a signal of a constant duty ratio when receiving data, and a first coil provided on a surface facing the data carrier, and is based on a transmission signal given from the transmission control circuit. An oscillating circuit that intermittently oscillates; a reception control circuit that includes a second coil provided on a surface facing the data carrier, and that reads data by waveform-shaping a signal obtained in the second coil; The data carrier is a third carrier provided facing the write / read control unit.
A resonance circuit including a coil, a demodulation unit that demodulates a signal based on an envelope signal and a carrier pulse of a resonance signal received by the resonance circuit, and a count-up signal that counts carrier pulses included in the resonance signal , A voltage monitoring means for monitoring the voltage level obtained from the resonance circuit and decreasing the count value to be counted up by the counter according to the decrease of the voltage level, a memory, and data from a data carrier. Reverberation control means for controlling the reverberation of the resonance circuit by the data read from the memory based on the count-up timing from the counter while the oscillation of the oscillation circuit is stopped during the transmission of
A non-contact communication device comprising: 2. A contactless communication device comprising: a data carrier; and a write / read control unit for transmitting data to the data carrier and receiving the transmitted data, the write / read control unit. Has a transmission control circuit for generating a signal of a constant duty ratio when receiving data, and a first coil provided on a surface facing the data carrier, and is based on a transmission signal given from the transmission control circuit. An oscillating circuit that intermittently oscillates; a reception control circuit that includes a second coil provided on a surface facing the data carrier, and that reads data by waveform-shaping a signal obtained in the second coil; The data carrier is a third carrier provided facing the write / read control unit.
And a demodulation means for demodulating a signal based on a carrier pulse and its envelope signal, and a resonance circuit including a coil, and a demodulation means for discriminating a resonance signal received by the resonance circuit. A counter that counts carrier pulses and outputs a count-up signal at a predetermined count value, and a voltage monitoring unit that monitors the voltage level obtained from the resonant circuit and reduces the threshold voltage of the comparator in accordance with the decrease in the voltage level. A reverberation for controlling the reverberation of the resonance circuit by the data read from the memory based on the count-up timing from the counter while the oscillation of the oscillation circuit is stopped during the transmission of the data from the memory and the data carrier. Control means,
A non-contact communication device comprising: