DE3107928A1 - DEVICE FOR THE CONTACTLESS TRANSFER OF A NUMBER VALUE - Google Patents

Description

VDO Adolf Schindling AG - 6000 Frankfurt / Main

Grafstrasse 103

G-S Sch-kl 1b65

Device for contactless transmission of a numerical value

The invention relates to a device for the contactless transmission of a numerical value, in particular

after
other of a measured value, / the preamble of the claim

1.
5

In such a device belonging to the prior art, the coupling resonant circuit belongs to one so-called transponder, which also has a switch, which in the case of air pressure monitoring

a vehicle wheel can be opened and closed depending on the pressure value and thus either the The coupling resonant circuit is left in the relatively undamped state or it is practically short-circuited. So that can with the undercarriage of the vehicle

part of the facility to determine whether the air pressure has dropped below a specified value is: For this purpose, the transmitting stage is first switched so effectively that it emits a frequency signal via the transmitting / receiving oscillating circuit, which

is received by the coupling resonant circuit when it is in the vicinity of the transmitting / receiving resonant circuit

-Ψ '

circle is located. The energy of the magnetically coupled in by a coil of the oscillating circuit The frequency signal stimulates the oscillating coupling circuit to oscillate at its natural frequency when the switch is open. In the case of a closed switch, no oscillation occurs in the coupling resonant circuit on. The transmit / receive oscillating circuit can now be "vaporized" by a control arrangement, so that the after switching off the transmission stage, the oscillation still occurring in it subsides very quickly. The Transmit / receive resonant circuit with the transmit stage as well operatively connected by the control circuitry. In the event that the switch of the Transponder is open and consequently a decaying oscillation occurs in the coupling resonant circuit, becomes this frequency signal during the reception phase received by the transmit / receive resonant circuit, if this is in the vicinity of the coupling resonant circuit - while in this when the switch is closed Reception phase from the send / receive resonant circuit no signal is received. To evaluate the received The receiving stage can use a frequency signal. . have electronic counter whose counting input is acted upon with reshaped counting pulses during a predetermined period of time derived from the received Frequency signal are shaped. The counter reading thus indicates that the switch of the transponder is open if a predetermined count is reached within the period of time, while in the other Case when the switch in the transponder is closed, no counting pulses get into the counter and a pressure that is too low is displayed with a display level.

In this device is disadvantageous that only two discrete values of a measured value can be transmitted without contact, depending on whether the coupling resonant circuit bridging switches, open or closed is.

The present invention therefore includes the task of to develop the device of the type mentioned at the beginning in such a way that it becomes contactless Transmission of a multi-digit numerical value in binary coding is suitable, which has a high transmission security can be expected.

This task is carried out by those specified in the

· * Part of claim 1 specified invention solved.

With this device, a numerical value present as a static binary bit sequence, for example a measured value, can advantageously be used from that at one

Movable object attached information carrier are accurately transmitted with great certainty to a fixed central unit. The transmission of one bit takes place during a cycle time, which is composed of the transmission phase, the damping phase and ^p the reception phase of the central unit. The bit sequence transmitted in this way is recovered as a bit sequence in the receiver stage of the central unit with a demodulator. '

^ Despite the high transmission security - if a Minimum distance between the coupling resonant circuit and the send / receive resonant circuit is given - the device is relatively inexpensive overall.

This is especially true if the facility is claimed 2 is trained. This development enables the information carrier to operate without own energy source, so that it can be described as a passive information carrier. The functions the passive information carrier can nonetheless be relatively complex with one or more electronic assemblies are executed.

An electronically controlled switch is expediently short-circuited as the coupling resonant circuit Switch is provided, which quickly corresponds to the bit sequence to be transmitted with little energy consumption can be operated.

In detail, the means provided in the information carrier for sequential transmission control are advantageously designed according to claim 4. The hereinafter provided counter which controls a data selector which consisting selects bits to be transmitted of the numerical value in succession and for control. 'Passes ■ the electronic switch allows a reliable operation of the device when, as provided, controlled by clock pulses the received frequency signal can be obtained.

The counter and the data selector are advantageously switched off in the passive information carrier Frequency signal obtained supply voltage fed.

Further details and advantages of the invention emerge from the following with reference to the drawing described embodiments. Show here:

1 shows a block diagram of the entire device for contactless digital transmission coded numerical values;

2 shows timing diagrams of essential functions of this device;

3 shows a special embodiment of the passive information carrier; and

4 shows information and signal sequences of the device which is designed according to FIG. 3.

In Fig. 1, the central unit comprises a control circuit arrangement (I \ which a transmitting stage (£), a receiving stage (3) with an amplifier - demodulator and an evaluation circuit (5), and a damping stage (6) supplied with control signals.

The transmission stage (2), the attenuation stage (6) and the Amplifier-demodulator are connected to a transmitting / receiving oscillating circuit (7), which is connected to a coil (8) and a capacitor (9) is constructed as a parallel resonant circuit.

The central unit is attached to a stationary object, while the one described below passive information carriers can be arranged on an object that is movable in relation to this:

The information carrier comprises a coupling oscillating circuit (9) consisting of a coil (10) and a Capacitor (11) also as a parallel resonant circuit

switched. The oscillating coupling circuit is short-circuited by an electronically controllable switch (12).

A control input (13) of the electronically controlled switch is from the output of means (14) to Transmission control powered. The transmission control means are in parallel lines Connection to an information store (15). In this the numerical value to be transmitted is a static one binary bit sequence stored.

The means for transmission control are fed by means (16) for clock recovery, which with the coupling resonant circuit (9) are connected.

in connection

Also with the coupling resonant circuit (9) / are means (17) for generating the supply voltage a frequency signal fed in by the oscillating coupling circuit supply a DC voltage to the means for clock recovery and transmission control.

The function of the device according to FIG. 1 is explained below with reference to FIG. 2: The signals emitted by the control circuit arrangement 1 - line a - during a Sending phase the Sendesi: ufe for the delivery of a high-frequency Oscillation to the sending / receiving oscillating circuit (7), which is referred to as a transmission burst. The coupling oscillating circuit is created by the transmit burst (9) according to line c, stimulated to a natural oscillation which initially fades, since the coils (8) and (10) are magnetically coupled to one another

when the information carrier is in the vicinity of the central unit.

In the damping phase following the sending phase, the sending / receiving oscillating circuit (7) is short-circuited by the damping stage, while the voltage in the coupling oscillating circuit can continue to oscillate according to line c when the electronically controlled switch (12) is open. Specifically, the waveform of the voltage depends on the coupling resonant circuit, as will be shown _/ on whether "1" is to be transmitted from the information carrier a logic ⁰ O ^w or logic. It should be anticipated that a logic "1" is transmitted in the left part of the line c and a logic "0" is transmitted in the right part of the line c.

In any case, the voltage in the coupling resonant circuit becomes according to line d, a direct voltage through the means (17) for supply voltage generation educated. In addition, a clock pulse is recovered from the voltage on the oscillating circuit, at the beginning of the rising tension in the line c. This recovered tact is not shown in FIG. It feeds the means (14) for transmission control, which takes place at every cycle Query one bit of the numerical value stored in binary form from the information memory. In the left part of the lines in FIG. 2, a logical "1" is queried, as is the transmission control means Called data selector - left idle,

the/

so that electronically controlled switch (12) remains open, compare lines e (output from data selector) and f (control signal for electronic

■ At-

Counter). When the switch (12) is open, the sounds Voltage on the coupling resonant circuit corresponding to the left part of the line c only slowly decreases and can during the reception phase - compare trace g in the de-excited transmit / receive resonant circuit a Induce voltage that first rises and then subsides.

The voltage induced in the transmitting / receiving oscillating circuit is generated in the amplifier-demodulator during the receiving phase (4) demodulates and generates an output signal corresponding to trace h, which is the Evaluation circuit (5) is supplied.

Is displayed during a subsequent period consisting of transmission phase, damping phase, and receive phase, as shown in the right part of line segments in Fig. 2, logic ¹¹ O "interrogated next bit from the means for transmission control (14) from the information store, §o the signal at the output of the transmission control means changes - trace e - and sends a control signal corresponding to trace f to the electronically controlled switch (12), which closes the switch. Therefore, in trace c, the voltage on the oscillating circuit sounds after the transmission phase or damping phase very quickly and can induce practically no voltage in the transmit / receive oscillating circuit (7) during the subsequent receive phase, see line g.

At the output of the amplifier demodulator, a temporal bit sequence is thus obtained in successive forms Reception phases that correspond exactly to the stationary bit sequence in the information memory 15. 5

This bit sequence can be processed further in the evaluation circuit, in particular with a . bit sequence of a numerical value stored therein are compared to match the Determine numerical value in the information memory 15. This is the principle of transmission of a contactless "electronic key" for which the invention can advantageously be used, since the information carrier can be made very compact and does not require its own energy source.

The electronics in the information carrier can do this be designed with discrete components, hybrid or integrated. The coding of the The numerical value can be directly in the means 14 for transmission control, if this as ROM are formed.

A simple embodiment of the as electronic Key trained information carrier is shown in figure. 3 shown in the same elements as in Figure 1 are provided with matching reference numerals:

match between Figures 1 and 3 of the oscillating coupling circuit 9 with coil 10 and capacitor as well as the electronically controlled switch 12 connected in parallel with the control input

A diode 18 for rectifying the frequency signal is connected to the oscillating coupling circuit, so that a supply voltage is formed from this, which is smoothed with a capacitor 19. Furthermore, from the frequency signal from the coupling resonant circuit via a further rectifier 19, which is connected to a resistor capacitor combination 20, a clock pulse obtained. One DC voltage line is routed to a counter 21 and to a data selector 22 for power supply. A clock line is connected to a clock input of the counter 21 and also to an AND element 23, which also has an output "OUT" of the data selector with the control input 13 of the electronically controlled switch 12 connects.

Outputs, for example 24, 25, 26 of the counter 21 are connected to address inputs, for example 27, 28, 29 of the data selector connected, on the other hand in connection with one of the number of bits of a bit sequence corresponding number of switches 30, 31 - 33 is.

The number stored stationary in the information carrier, namely the binary bit sequence of this number, is that is, represented by the open or closed switches, each of which is assigned to a bit is.

The open or closed switches determine a voltage value at the data inputs 34, 35, 36 of the data selector. Depending on the status of the address inputs 27, 28, 29, which is determined by the counter, the output "OUT" of the data selector assumes the state of one of the data inputs 34, 35, 36. It will

So the data inputs in the data selector "when counting up the counter with clock pulses one after the other queried and forwarded via the AND gate 23 to the control input 13 of the switch 12.

FIG. 4 shows the logic states at various points on the information carrier according to FIG. 3 and the rest of the device according to FIG. 1, as well as some characteristic signal curves: ■

According to line a in FIG. 4, a binary number should be generated after the switches 30-33 have been set at the data inputs 34 - 36 or XO - X7 is pending.

For this purpose, a clock pulse is obtained after each transmission phase, which counts up the counter according to line b. For example, during the first "0" of the counter status in line b at the negated output ¹¹ OUT "of the data selector - also called the data selector - a logic" 0 "is generated, since the corresponding input of the data selector is fed with a logic" 1 ". As a result, the voltage at the coupling resonant circuit, which is indicated as an envelope curve in line d, gradually decays during the reception phase, as shown in more detail in the left part of figure line c Voltage pulse corresponding to line h in FIG. 2, which in line e in FIG. 4 merges with a corresponding voltage pulse in the preceding cycle time

signals a logical "1" again at the output of the amplifier demodulator. In the following cycle time - the time between two transmission phases is referred to as cycle time - a logical "O" is queried from the data input of the data selector 22, which ^{makes a logical M} 1 "appear at the negated output of the data selector short-circuited and the voltage in the coupling resonant circuit decays immediately after the end of the transmission phase and the damping of the transmitting / receiving resonant circuit. This shows schematically the curve in line d in FIG. 4 and, more precisely, the right-hand part of line c in FIG This state of the transmitting / receiving oscillating circuit results in a low signal level at the output of the amplifier demodulator 4, which contains a logic "0" as information, compare line f.

The above processes are repeated for one cycle time each until the entire binary coded Number is transmitted from the information carrier to the central unit. Since this is followed by a If a new transmission begins, a special bit should be specified in the information carrier signals the end of the transmission of a numerical value.

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Claims (1)

Claims Device for contactless transmission of a. Numerical value, in particular a measured value from a movable object to a stationary object relative to this, with a transmitting stage emitting a frequency signal and a receiving stage comprising a demodulator, which can be connected to at least one transceiver oscillating circuit, as well as an information carrier with a coupling oscillating circuit arranged on the movable object and a short-circuiting switch, whereby when the switch is open, a frequency signal can be applied to the receiving stage by the coupling resonant circuit, with means _# which switch the transmitting stage and the receiving stage in a clocked alternating manner and, in between, if necessary, activate means for steaming the transmitting / receiving resonant circuit, *
characterized in that 1) that for the digitally coded, sequential transmission of the numerical value as a bit sequence in the information carrier in the rhythm of the transmission phases a) means (16) for clock recovery are connected to the coupling resonant circuit (9), b) connected to a memory (fl5) of the numerical value Means (14) for sequential transmission control by the recovered clock are controllable c) the switch (12) short-circuiting the coupling resonant circuit by the means for sequential Transmission control can be actuated 3107328 2) that the receiver stage (3) with a demodulator (4) is designed to recover the bit sequence, 2. Device with a passive information carrier according to claim 1, characterized in that with the coupling resonant circuit (9) via a rectifier (18) a memory (capacitor 19) for generating an assembly of the information carrier feeding Supply voltage is connected. 3 «device according to claim 1, characterized in that more short-circuiting than the coupling resonant circuit (9) a Switch 02) / electronically controlled switch provided is. 4. Device according to claims 1 and 3 »characterized in that that as a means for sequential transmission control a fed with the recovered clock pulses Counter (21) is provided, the count outputs (24, 25, 26) with address inputs (27, 28, 29) one Data selector (22) are connected that data inputs (34, 35, 36) of the data selector with one each Switch (30, 31, 33) is coupled for each bit of the numerical value and that an output (OUT) of the data selector is in communication with a control input (13) of the controlled switch. 5. Device according to claims 2 and 4, characterized in that that the counter and the data selector (22) via the rectifier (18) from the coupling resonant circuit (9) can be acted upon with the supply voltage.