JPH0732369B2 - Data communication device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to first and second contactless proximity using an induction electromagnetic field.
The present invention relates to a data communication device for performing data communication between units.

[Prior art and its problems]

(Prior Art) Conventionally, for example, as disclosed in JP-A-62-63050,
A data storage device that holds each tool data is provided in the tool shank of a machine tool, so that data can be serially transmitted from the data input / output device to the data storage device for writing or reading the written contents. A data transmission device based on the above has been proposed. In such a data transmission device, communication between the data input / output device and the data storage device is performed by using a constant high frequency signal and performing frequency shift keying (FSK) modulation thereof.

(Problems to be Solved by the Invention) However, according to such a conventional data transmission device, a PLL circuit for demodulating an FSK signal is required in the data storage device and the data input / output device, which consumes a lot of power. It requires electricity. The data storage device may rectify the AC voltage induced from the data input / output device and use it as a power supply. At this time, if the power consumption is high, data communication cannot be performed unless the induced voltage is high. It has the drawback of being shorter. Further, when a battery is provided on the data storage device side, there is a drawback that the battery life becomes short. On the other hand, in order to reduce the power consumption of the data storage device, the applicant has made it possible to discontinuously change the resonance frequency of the resonance circuit based on the transmission data when transmitting the data from the data storage device to the data input / output device. The proposed method is proposed (unpublished). In this case, the power consumption of the data storage device can be reduced, but since the communication range is determined by the coupling coefficient with the data input / output device, the communication distance can be increased even if the output from the data input / output device is increased. There is a drawback that you cannot do it.

[Object of the Invention]

The present invention has been made in view of the above problems of the conventional data transmission apparatus, in which transmission signals are mutually transmitted by using a carrier of a constant frequency, and the communication distance is improved by improving transmission / reception efficiency. Making it larger is a technical issue.

[Constitution and effect of the invention]

(Means for Solving Problems) The present invention is a data communication apparatus for performing half-duplex data transmission of serial data between a first unit and a second unit, and is shown in FIGS. 1 to 3. So the first unit
An oscillator having a first coil provided on a surface facing the second unit, and a first and a second duty ratio corresponding to a transmission data signal at the time of data transmission, and a constant third at the time of data reception. And a resonance frequency substantially equal to the oscillation frequency of the oscillator, for generating a transmission pulse signal of a constant cycle having a duty ratio of, and for intermittently oscillating the oscillation by applying the transmission pulse signal of the constant cycle to the oscillator. And a first resonance circuit including a second coil provided on a surface facing the second unit, and a timing corresponding to a signal corresponding to the transmission pulse of the transmission pulse generating means when the oscillation of the oscillator is stopped. A reception gate signal generating means for generating a reception gate signal having: and an electromagnetic wave obtained in the first resonance circuit while the reception gate signal of the reception gate signal generating means is given. What has a detection circuit for detecting the conducted signal, a sample hold circuit for sampling the output of the detection circuit at a predetermined timing of the reception gate signal, and a first comparator for discriminating the hold signal of the sample hold circuit at a predetermined level And the second unit has a resonance frequency substantially equal to the oscillation frequency of the oscillator of the first unit, and the second resonance unit includes a third coil provided on a surface facing the first unit. Circuit, a detection circuit for detecting a signal obtained in the second resonance circuit, a second comparator for obtaining a transmission pulse signal by discriminating the detection output at a predetermined threshold level, and data from the first unit Data demodulation means for demodulating the transmission data signal from the transmission pulse signal of the first and second duty ratios based on the output of the second comparator during reception, the second resonance circuit and the A switching element connected between the first unit and the switching element at the timing of stopping the oscillation of the oscillator based on the transmission pulse signal of the third duty ratio obtained from the second comparator during data transmission to the first unit. And reverberation control means for controlling reverberation generated in the second resonance circuit by intermittently corresponding to the transmission data.

(Operation) According to the present invention having such a feature, the first unit intermittently oscillates the oscillation of the oscillator and changes the duty ratio at the time of transmission, thereby transmitting the binary signal to the second unit side. I am trying to send it to you. The second unit detects the signal and discriminates it at a predetermined threshold level to demodulate the transmission pulse signal, and further demodulates the original transmission data signal based on the duty ratio of the signal. Further, when transmitting data from the second unit to the first unit, the oscillation of the oscillator is interrupted by a constant third duty ratio from the first unit, and the resonance of the second unit occurs when the oscillation is stopped. The switch provided in the circuit is intermittently operated according to the transmission data signal to control the reverberation obtained in the resonance circuit of the first unit. The first unit generates a reception gate signal within the oscillation stop period based on the transmission pulse signal given to the oscillator, extracts only reverberation by the reception gate signal, and detects the reverberation. Then, the signal is sampled at a predetermined timing of the reception gate signal, given to the first comparator, and discriminated at a predetermined threshold level to demodulate the transmission signal obtained from the second unit.

As described above, according to the present invention, half-duplex data transmission of serial data is performed between the first and second units by utilizing electromagnetic coupling. Since the data demodulating means of the second unit demodulates the signal based on the pulse width, there is no need to use a PLL circuit or the like, which is relatively simple and consumes less power. Therefore, when the electric power of the second unit is obtained from the first unit, the transmission distance can be increased because the electric power consumption is small. When transmitting data from the second unit to the first unit, the reverberation of the signal obtained from the first unit is controlled based on the transmission data. If the oscillation output given to the unit is increased, the reverberation level can be increased accordingly. Therefore, the resonance signal of reverberation obtained in the first unit also becomes large, so that the data transmission distance can be lengthened. Further, since the resonance circuits provided in the first and second units are made to substantially match the oscillation frequency of the oscillator, it is possible to perform data transmission with high efficiency and improve the SN ratio. The effect is obtained.

[Explanation of Examples]

(Structure of Embodiment) FIG. 2 is a block diagram showing an overall structure in which a data communication device according to an embodiment of the present invention is applied to an article identification system. In the figure, the data communication device has a writing / reading control unit 1 which is a first unit, and an ID unit 3 which is a second unit attached to an article 2 or the like. The writing / reading control unit 1 has first and second coils L1 and L2 at positions facing the ID unit 3, and the ID unit 3
Also has a third coil L3 at a position facing these coils. The writing / reading control unit 1 is connected to, for example, a higher-level control device 4. The upper control device 4 sends a transmission control signal (CT) to the writing / reading control unit 1 and then sends transmission data SD, and reads the received data RD obtained from the writing / reading control unit 1.

As shown in the detailed block diagram of FIG. 1, the write / read control unit 1 includes a clock generator 11 for generating a constant clock signal, a time controller 12 for generating a timing signal on the basis of the clock signal, and a transmitter. A pulse generation circuit 13 is provided. The time controller 12 sends a transmission / reception switching signal to the transmission pulse generation circuit 13 and the reception gate generation circuit 14 when the transmission control signal (CT) obtained from the upper control device 4 is given. After the transmission control signal is given, the transmission data SD is sent to the transmission pulse generation circuit 13. The transmission pulse generation circuit 13 counts the clock of the clock generator 11 for a predetermined period at the timing when the reception switching signal from the time controller 12 is in the transmission state, and firstly transmits the clock in a predetermined period according to the transmission data SD.
And a transmission pulse signal having a second duty ratio, the output of which is provided to the oscillator 15. The oscillator 15 oscillates at a constant frequency only when a transmission pulse signal is given from the transmission pulse generation circuit 13, and its oscillation output is for transmission via the amplifier 16
Is given to the coil L1. The write / read control unit 1 is also provided with a second coil L2 for receiving. A capacitor C1 is connected in parallel to the coil L2 to form a first resonance circuit 17 that resonates at the oscillation frequency of the oscillator 15, and an induced voltage obtained across the first resonance circuit 17 is applied to the amplifier 18. The amplifier 18 amplifies the induced voltage and supplies its output to the detection circuit 20 via the analog switch 19. The reception gate generation circuit 14 generates a reception gate signal delayed by a predetermined time, for example, one clock from the fall of the transmission pulse when the transmission / reception switching signal provided by the time controller 12 is in the reception state. The reception gate signal is given to the analog switch 19 as a gate signal. The reception gate signals of the clock generator 11 and the reception gate generation circuit 14 are also given to the sampling signal generation circuit 21. The sampling signal generation circuit 21 supplies a predetermined timing of the reception gate signal, for example, a signal for one clock immediately before the end, to the sample hold circuit 22 as a sampling signal. The detection circuit 20 detects a signal obtained via the analog switch 19 to obtain an integrated signal or an envelope signal thereof, and the detection signal is given to the sample hold circuit 22. Sample hold circuit
22 holds an input signal based on the sampling signal, and its output is given to the first comparator 23. The comparator 23 obtains a binary signal by discriminating the signal held at a predetermined threshold level, and its output is given to the host control device 4 as a reception signal RD.

As shown in FIG. 3, the ID unit 3 has a second resonant circuit 30 including a coil L3 and a capacitor C2 provided on the surface facing the write / read control unit 1, and an induced voltage across the second resonant circuit 30. Are provided to the detection circuit 31. The detection circuit 31 detects this signal, and its output is the second comparator.
Given to 32. A predetermined threshold level is set in the comparator 32, and the detection output is discriminated by the threshold. The output of the comparator 32 is given to the counter 33 and the digital comparator 34. Counter 33 is reset by the output of comparator 32 to provide a clock generator while the transmit pulse is applied.
The clock signal is counted in a constant cycle of 35, and the count value is given to the digital comparator 34. The digital comparator 34 compares the count value of the counter 33 with a constant count value when a comparison signal is given from the comparator 32, and outputs "L" or "H" depending on whether or not the count value is exceeded. The output is given to the memory control unit 36. A memory 37, which is a storage unit of the ID unit 3, is connected to the memory control unit 36. Since the signals obtained from the write / read control unit 1 are data and commands, the memory control unit 36 writes the data given based on this command in the memory 37 and reads the data in the memory 37. To control. Memory controller
The output of 36 is provided to the reverberation control pulse generator 38. The reverberation control pulse generator 38 outputs the transmission data based on the transmission data to be transmitted to the writing / reading control unit 1 read from the memory control unit 36 at a predetermined timing when the output of the comparator 32 becomes "L" level. The reverberation control pulse having a predetermined width is generated at the "H" level. Now, at both ends of the resonance circuit 30, FETs 39 and 40, which are switching elements, are respectively connected to the ground through a resistor. The FETs 39 and 40 use the resonance circuit 30 based on the reverberation control pulse from the reverberation control pulse generator 38.
Both ends of are controlled so as to be grounded. Further, in this embodiment, the ID unit 3 has a battery 41 as shown in the drawing, and power is supplied to each part from the battery 41.

Here, the counter 33, the digital comparator 34, and the clock generator 35 are comparators having first and second duty ratios.
A data demodulating means 42 for discriminating the transmission data SD on the basis of the output of 32, that is, the transmission pulse signal given from the write / read control unit 1 is constituted. The residual control pulse generator 38 and the FETs 39 and 40 which are switching elements for grounding both ends of the resonance circuit 30 constitute reverberation control means 43 for controlling the reverberation of the resonance circuit 30.

(Operation of Embodiment) Next, the operation of this embodiment will be described with reference to a time chart. First, when transmitting a signal from the writing / reading control unit 1 to the ID unit 3, a transmission control signal CT is sent from the host control device 4 to the time controller 12. Then, the time controller 12 gives a transmission switching signal to the transmission pulse generating circuit 13. Then, as shown in FIG. 4 (a), the transmission data SD is sent from the higher-level control device 4.
A signal (for example, “HLLH” as illustrated) is applied to the transmission pulse generation circuit 13. Then the transmission pulse generation circuit
As shown in FIG. 4 (b), 13 is the first and the first corresponding to the logical level of the transmission data at a constant cycle T from times t ₁ , t ₃ , t ₅ and t ₆ .
A transmission pulse signal having a second duty ratio is generated. The oscillation of the oscillator 15 is interrupted by this signal as shown in FIG. 4 (c). Therefore, when the ID units 3 are close to each other, the driving time of the oscillator 15, that is, the times t _{1 to} t ₂ , t _{3 to} t _4, ... Are shown at both ends of the resonance circuit 30, as shown in FIG. Thus, a signal with a constant amplitude is obtained, and then a signal that attenuates is obtained. Since this signal is detected by the detection circuit 31 and compared at a predetermined threshold level, the comparator 32 obtains the same signal as the transmission pulse signal as shown in FIG. 4 (e). This signal is given to the counter 33 and the digital comparator 34. When the counter 33 starts counting from the time t ₁ , a count value larger than a predetermined value is obtained at the time t ₂ when its output falls, and when the counting starts from the time t ₃ , the time t ₄ In, the count value lower than the predetermined value is obtained. Therefore, the digital comparator 34 discriminates the count values at times t ₂ and t ₄ , and outputs a signal to the memory controller 36 at a timing delayed by one cycle from the transmission data SD as shown in FIG. 4 (f). In this way, data can be transmitted from the write / read control unit 1 to the ID unit 3. Further, unlike the FSK signal, only a signal of a constant frequency is intermittently provided, so that the resonance frequency of the resonance circuit 30 can be matched with the oscillation frequency of the oscillator 15 to perform data transmission with high efficiency. Further, if the output of the oscillator 15 of the write / read control unit 1 is increased, the voltage level induced in the ID unit 3 is increased accordingly, so that the communication distance can be increased by the oscillation output.

Next, when transmitting data from the ID unit 3 to the writing / reading control unit 1, the transmission / reception switching signal of the time controller 12 of the writing / reading control unit 1 is first switched to the receiving state, and the transmission pulse generation circuit 13 Generates a transmission pulse signal having a constant third duty ratio as shown in FIG. 5 (a), for example, a constant cycle T with a duty ratio of 50%. Then, the oscillator 15 is intermittently turned on and off, so that FIG.
An oscillating signal as shown in (1) is transmitted to the ID unit 3 from the coil L1. Therefore, the comparator 32 outputs a clock signal with a duty of 50% as shown in FIG. 5 (c). Based on this clock signal, the memory control unit 36
The data signal is read out. FIG. 5 (d) shows an example of a signal in which the signal read from the memory controller 36 is "HLHL", and this signal is given to the reverberation control pulse generator 38. The reverberation control pulse generator 38 outputs a reverberation control pulse having a predetermined width as shown in FIG. 5 (e) at the trailing edge of the comparator 32 based on the logic level of this signal. This signal is given to the FETs 39 and 40 to be intermittently connected. Therefore FET39,40
In the off state, an attenuation signal is generated in the resonance circuit 30 as shown after time t _{9 in} FIG. 5 (f), but after the time t ₁₁ when the FETs 39 and 40 are turned on, the resonance circuit 30 is turned off. Since both ends are grounded, almost no reverberation occurs in the resonance circuit 30 of the ID unit 3. On the other hand, the signal obtained in the resonance circuit 17 of the write / read control unit 1 has a constant high amplitude level during the time t _{8 to} t ₉ , t _{10 to} t ₁₁ ... Subsequent times t _{9 to} t ₁₀ , t _{11 to} t ₁₂ ... are IDs
A low level reverberation remains according to the reverberation of the resonance circuit 30 of the unit 3. Then, as shown in FIG. 5 (h), a reception gate signal is generated from the reception gate signal generation circuit 14 at a constant cycle shorter than the cycle when the transmission pulse is turned off, and detection is performed through the analog switch 19 which is closed only during that period. A signal is transmitted to the circuit 20. Immediately before the fall, a sampling signal is given to the sample hold circuit 22 as shown in FIG. Therefore, the sample hold circuit 22
Since the output of the comparator is discriminated from the threshold value by the comparator 23, a signal as shown in FIG. 5 (l), that is, a memory read signal similar to that shown in FIG. 5 (d) is output from the comparator 23 as the write / read control unit. 1 will be transmitted with a delay of the transmission cycle T.

In this embodiment, a counter for counting clocks and a digital comparator are used as the data demodulating means of the ID unit 3, and the output of the digital comparator discriminates into a binary signal corresponding to the pulse width of the oscillation signal. Various configurations for demodulating the width into a binary signal, for example, a data demodulating means is configured by an integrating circuit for integrating the signal obtained by the comparator and a comparator for discriminating the integrated output at a predetermined threshold level. Good.

In addition, this embodiment shows an example in which a battery is held as the power source of the ID unit 3, but a clear / smoothing circuit is connected to the resonance circuit of the ID unit 3 and the DC voltage obtained from the circuit is Power may be supplied to each block as a power source.
In this case, the transmission data SD given from the control device 4 is further Manchester-encoded so that the average period of the transmission pulse is constant, and the Manchester-encoded signal, that is, “HL” for the logical “H” level, Regarding the logic "L", it is preferable to transmit the transmission data by giving the signal of "LH" to the transmission pulse generation circuit 13 as the transmission data. In this way, the data transmission rate is halved compared to the case without Manchester encoding, but the average value of the drive time of the oscillator 15 does not change with time and an oscillation signal of a constant average value is given, so the ID unit It is possible to perform data transmission without changing the DC voltage of 3.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a writing / reading control unit of an article identification system according to an embodiment of a data communication apparatus of the present invention, FIG. 2 is a block diagram showing the overall configuration, and FIG. 3 is an ID unit. FIG. 4 is a time chart showing waveforms of various parts when data is transmitted from the write / read control unit to the ID unit, and FIG. 5 is a signal from the ID unit to the write / read control unit. 3 is a time chart showing waveforms of various parts when transmitting a signal. 1 ... Writing / reading control unit, 3 ... ID unit, 4
...... Control device, L1, L2, L3 …… Coil, 11 …… Clock generator, 12 …… Time controller, 13 …… Transmission pulse generation circuit, 14 …… Reception gate signal generation circuit, 15 …… Oscillator, 17 , 30 …… Resonance circuit, 19 …… Analog switch, 20,
31 …… Detection circuit, 22 …… Sample hold circuit, 23,32
…… Comparator, 33 …… Counter, 34 …… Digital comparator, 36 …… Memory control unit, 37 …… Memory, 38 …… Residual control pulse generator, 41 …… Battery, 42 …… Data demodulation means, 43 ...... Reverberation control means

Claims (1)

[Claims] 1. A data communication device for performing half-duplex data transmission of serial data between a first unit and a second unit, wherein the first unit is on a surface facing the second unit. An oscillator having a first coil provided, and a first and a second oscillator that correspond to a transmission data signal when transmitting data.
A transmission pulse signal having a constant duty cycle and having a constant third duty ratio when receiving data, and transmitting the transmission pulse signal having the constant cycle to the oscillator to intermittently oscillate the oscillation. Generating means; a first resonance circuit having a resonance frequency substantially equal to the oscillation frequency of the oscillator and including a second coil provided on a surface facing the second unit; Receiving gate signal generating means for generating a receiving gate signal having a timing when the oscillation of the oscillator is stopped by receiving a signal corresponding to the transmission pulse of the means, and the receiving gate signal generating means for receiving the receiving gate signal of the receiving gate signal generating means. A detection circuit for detecting an electromagnetic induction signal obtained in the first resonance circuit, and an output of the detection circuit at a predetermined timing of the reception gate signal. A sample-hold circuit for sampling, and a first comparator for discriminating a hold signal of the sample-hold circuit at a predetermined level, wherein the second unit has an oscillation frequency of an oscillator of the first unit. A second resonance circuit including a third coil having a resonance frequency substantially equal to, and including a first coil provided on a surface facing the unit; and detection for detecting a signal obtained by the second resonance circuit. A circuit, a second comparator for obtaining a transmission pulse signal by discriminating the detection output at a predetermined threshold level, and a second comparator based on the output of the second comparator when data is received from the first unit. 1, a data demodulating means for demodulating a transmission data signal from a transmission pulse signal having a second duty ratio; and a switching element connected between the second resonance circuit and ground. On the basis of the transmission pulse signal of the third duty ratio obtained from the second comparator at the time of data transmission to the first unit, the switching element is intermittently associated with the transmission data at the timing of oscillation stop of the oscillator. And a reverberation control unit that controls reverberation generated in the second resonance circuit.