MXPA97000571A - Device for the transmission of data or ener - Google Patents

Abstract

Device for the transmission of data or energy. The device according to the invention has an oscillating circuit (3,4), which is driven by an excitation variable for oscillation. The oscillation is transmitted in a transformer way to a transponder oscillating circuit (5, 6). For the transmission of energy or data to be as effective as possible, the current or voltage in the oscillating circuit of the antenna (3, 4) is measured and compared with a theoretical quantity. In case of deviation, a correction value is generated, through which the excitation current is increased or the resonance frequency fR is equalized to the excitation frequency fE due to the additional connection of an impedance (C, L) to the circuit oscillating antenna (3,

Description

DEVICE FOR DATA TRANSMISSION Q ENERGY TECHNICAL FIELD The invention relates to a device for the transmission of data or energy. A device of this type is used in particular for an anti-theft system for a motor vehicle, in which coded information is transmitted from a key and to a lock and in the reverse direction. STATE OF THE ART A known device (DE 44 30 360 Cl) has a stationary transceiver, which contains an oscillating circuit. In the transceiver an oscillation is forced through an excitation quantity, whose energy is transmitted to a transponder. The transponder also has an oscillating circuit, through which energy is received and encoded data is retransmitted to the transceiver. In case in this known device, success is not achieved first in the first detection of the encoded data, then the oscillating circuit of the transceiver is "detuned". To this end, the resonance frequency of the oscillating circuit or its excitation frequency is modified. When the oscillating circuit is detuned due to tolerances of the construction groups, then this detuning also remains in the case of use of the transceiver in an anti-theft system. Therefore, then each transmission process must be carried out at least twice. The problem of the invention is to create a device for the transmission of data or energy, in which energy or data are transmitted in the most effective way possible. DESCRIPTION OF THE INVENTION The problem is solved according to the invention by means of the characteristics of the patent claim 1. In this case, a stationary transceiver has a first oscillating circuit with a coil and a capacitor. The oscillating circuit is excited by means of an excitation variable with an excitation frequency to form an oscillation. The current and / or the voltage of the excitation variable are measured and in the event that the current or voltage deviates from a theoretical value, then a correction value is generated. Advantageous configurations of the invention are characterized in the dependent claims. More advantageously, this correction value is stored and used in subsequent inductive transmissions of data or energy in an anti-theft system. DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the invention are explained in detail below with the aid of the schematic drawings. In this case: Figure 1 shows a schematic block diagram of the device according to the invention. Fig. 2 shows a resonance curve of an oscillating circuit of the device according to Fig. 1, and Fig. 3 shows a connection diagram of a transceiver of the device according to Fig. 1. BEST WAY FORECAST KNOWN A device according to the invention for transmission of data or power has a stationary transceiver 1 (FIG. 1), which cooperates with a portable transponder 2 through a transformer coupling, when transponder 2 is in the vicinity of transceiver 1. Transceiver 1 first transmits energy to the transponder 2. Transponder 2 stores an encoded information, which is retransmitted to transceiver 1 (energy transmission and data transmission are represented by a double arrow marked with broken lines). For the transmission of energy or data, the transceiver 1 has an antenna 3 in the form of a coil, which together with a capacitor 4 forms a first oscillating circuit (hereinafter referred to as the oscillating circuit of the antenna 3, 4). The antenna 3 is coupled inductively or in a transformer fashion with a coil 5 of the transponder 2. The coil 5 of the transponder 2 forms together with a capacitor 6 arranged in series or parallel to it a second oscillating circuit (hereinafter referred to as the oscillating circuit of the transponder 5, 6). The oscillating circuit of the antenna 3, 4 is fed from a generator or an oscillator 7 with an alternating voltage or an alternating current at the clock frequency of an excitation frequency fE, as soon as a supply unit 8 of the oscillator is connected 7. In this way, the oscillating circuit of the antenna 3, 4 is excited for an oscillation with the excitation frequency fE. The field excited by the antenna 3 induces in a coil 5 of the transponder 2 a voltage, when the transponder 2 is arranged in the vicinity of the transceiver 1. The oscillating circuit of the transponder 5, 6 is excited, on the one hand, for oscillation by means of of the oscillation of the oscillating circuit of the antenna 3, 4. The oscillating circuit of the transponder 5, 6 can be charged to the rhythm of the encoded information by means of a connected transponder-IC 9, in which a coded information is stored. In this way, the oscillating circuit of the antenna 3, 4 is charged or modulated to the rhythm of the encoded information due to the transformer coupling. The oscillating circuit of the antenna 3, 4 is forced through the oscillator 7 with an excitation variable at an oscillation with an excitation frequency fB. The voltage or output current of the oscillator 7 is used as the excitation variable. The oscillator 7 oscillates with the frequency of the oscillator fc. Between the oscillator 7 and the oscillating circuit of the antenna 3, 4 can also be arranged a frequency divider not shown, which divides the frequency of the oscillator f0 on the desired excitation frequency fE. Through the excitation variable, a stationary forced oscillation of the oscillating circuit of the antenna 3, 4 is obtained, which then oscillates with the excitation frequency fE. Each oscillating circuit has its own frequency or also called resonance frequency fR, which is determined through the components of the oscillating circuit, that is, through the inductance of the antenna 3 and the capacitance of the capacitor 4 in the oscillating circuit of the oscillating circuit. the antenna 4. The excitation current flowing through the antenna 3 is maximum when the oscillating circuit is excited with the excitation frequency fE equal to the resonance frequency fR (see the continuous curve in figure 2). In this way, the magnetic field, which is generated by the current I flowing through the antenna 3, is maximum. With this, the maximum energy is transmitted to the transponder 2. The maximum amplitude of the current I depends on the quality of the oscillating circuit. In case of high quality, the amplitude of current I is large and in case of low quality, the amplitude of current I is smaller. The power balance is illustrated with the help of the resonance curve (Figure 2), in which the frequency f is represented on the abscissa (x-axis) and the amplitude of the current I through the antenna 3 is represented on the ordinate (y-axis). The excitation frequency fE can be kept very constant by means of a regulated oscillator 7, while the resonance frequency fR is dependent on the components and their tolerances. When the excitation frequency fE is equal to the frequency fx and the resonance frequency fR is also equal to the frequency fl r then the current I flowing through the antenna 3 is maximum with a maximum amplitude of 1 ^ If the resonance frequency fR (= frequency f2) deviates from the excitation frequency fE (resonance curve shown in dashes in FIG. 2), then the oscillating circuit of the antenna 3, 4 is no longer optimally excited and only flows a current with the amplitude I2 through the antenna 3. The magnetic field generated in this way can then be too small for the transmission of data or energy. In the manufacture of the transceiver 1, due to the tolerances of the components, deviations of theoretical values can occur in the inductance of the antenna 3 and the capacitance of the capacitor 4. In this way, the resonance frequency fR of the oscillating circuit of the antenna 3, 4 is modified against the constant excitation frequency fE. When the device according to the invention is operated in such conditions, then the maximum energy is no longer transmitted to the transponder 2 and the data received from there can also be received only with very small amplitude. After the manufacture of the transceiver 1, it must first be determined whether the resonance frequency fR deviates from the excitation frequency fE to a greater extent than a given predetermined amount. To this end, the amplitude of the current I is measured through the antenna 3 or the voltage U in the capacitor 4 is measured with the aid of a measuring device 10. The measured amplitude is compared with a stable theoretical value. previously stored or stored. If the deviation is too large, a correction value is generated and stored in the measuring device 10. Depending on the correction value, the oscillating circuit of the antenna 3, 4 is then corrected for all transmissions between transceiver 1 and the transponder 2, with which a transmission takes place as effectively as possible between the transceiver 1 and the transponder 2. The oscillating circuit of the antenna 3, 4 can be modified in two different ways depending on the correction value, so that it has place an energy and data transmission as effective as possible. On the one hand, the resonance frequency fR of the oscillating circuit of the antenna 3, 4 can be approximated to the excitation frequency fE and, on the other hand, the current I can be increased through the antenna 3, that is, the excitation current. First, the modification of the resonance frequency fR (path represented by dashes in FIG. 1) is considered. By measuring the current I through the antenna 3, its maximum amplitude is first compared to a theoretical amplitude. If the current deviates too much from a theoretical current, then the resonance frequency fR deviates from a theoretical resonance frequency. By measuring the phase of the current and the voltage it can be determined whether the oscillating circuit of the antenna 3, 4 is inductively or capacitively detuned, since in the case of inductive detuning, the current I through the antenna 3 follows the voltage U with a delay in the measurement of a phase angle and in the case of a capacitive de-tuning, the current I is delayed with respect to the voltage U in the measurement of the phase angle. By means of the measured amplitude of the current I the magnitude of the detuning is known. By means of the comparison of the phases of the current I and of the voltage U, the direction of the detuning is known. The amplitude I and the angle of the phases then establish the correction value. Subsequently, a capacitance? C or an inductance? L as a function of the correction value via a capacitive and / or inductive network 11 is added to or removed from the oscillating circuit of the antenna 3, 4. In this way, the resonance frequency fR of the oscillating circuit of the antenna 3, 4 is modified. The capacitance? C and the inductance? L are set so that the resonance frequency fR approaches the excitation frequency fE by the additional connection or the withdrawal of the capacity? C and / or the inductivity? L. This corresponds in FIG. 2 to a displacement of the resonance curve shown in dashed lines to the left of the continuous plotted resonance curve. In this way, at the excitation frequency fE, a current I flows through the antenna 3, whose amplitude approaches the theoretical amplitude I1. The additional connection or withdrawal of capacitance? C and / or inductance? L is carried out only once after the manufacture of transceiver 1. For subsequent transmission processes these corrections are maintained, ie the additional connection or the withdrawal of capacity? C and / or inductivity? L. In this way, the oscillating circuit of the antenna 3, 4 is adapted to the excitation unit with the oscillator 7. More advantageously, the oscillating circuit of the antenna 3, 4 is manufactured in such a way that its resonance frequency fR, taking into account account the manufacturing tolerances, it is above the excitation frequency fE or the theoretical resonance frequency. In this way the device is simplified, since only capacitors must be added. When the oscillating circuit of the antenna 3, 4 is capacitively detuned only to a small extent, then the resonance frequency fR can be modified by withdrawing a capacity? C. On the other hand, if the oscillating circuit of the antenna 3, 4 is inductively detuned to a small extent, then the resonance frequency fR can be modified by the additional connection of a capacity? C. Next, a modification of the current I through the antenna 3 is considered. In case the oscillating circuit of the antenna 3, 4 is untuned, then at the excitation frequency fE only a current with the amplitude I2 flows through of the antenna 3, so that also the excitation current can be increased to the point that the amplitude of the current through the antennas becomes approximately equal to the amplitude It (resonance curve represented by dots in the figure 2 ) . For this purpose, the current I2 is first measured. Since the amplitude Ix of the ideal current is known, the correction value can be determined, in which current I2 must be intensified. In this procedure, the amplitude I3 of the maximum current through the antenna 3 increases when it has been excited with an excitation frequency fE equal to the frequency f2. Since the current increases, therefore, more energy must be supplied to the device, ie the excitation current must be increased considerably. The increase of the excitation current as a function of the correction value is only made once after the manufacture of the transceiver 1. For subsequent transmission processes, these corrections are maintained, that is, in all subsequent transmissions of data or energy it is keeps constant the excitation current determined by the correction value. This has the advantage that a constant magnetic field is generated. As a result, sufficient voltage is induced in the oscillating circuit of the transponder 5, 6 to retransmit data in reverse from the transponder 2 to the transceiver 1. The correction value can be stored and in each transmission process the current of the transponder can be influenced. excitation or by the additional connection or the withdrawal of the capacitance C and / or the inductance? L. In the device according to the invention, both corrections can also be carried out successively, that is to say, first modifying the resonance frequency fR and then the current I by correcting the excitation current. This may be the case when, by modifying the resonance frequency fR, no good approximation to the theoretical resonance frequency is yet achieved. In FIG. 3, a connection diagram of the device according to the invention is shown. In this case, the antenna 3 is activated through a bridge circuit, in whose branches there is a respective connection transistor Tx to T4. The transistors Tx to T4 are connected or disconnected in this case in pairs, that is, the couple Tx and T3 and the couple T2 and T4. The transistors Tx to T4 are activated during this time with the excitation frequency fE in such a way that a positive voltage and a negative voltage exist alternately in the antenna 3. In this way, a sinusoidal current flows with the frequency f equal to the excitation frequency fE through the antenna 3. Between the antenna 3 and the capacitor 4 there is a tap point, which is connected to the measuring device 10. for measuring the current I and the voltage U. With the measuring device 10 both the amplitude and the phase of the current I and the voltage U can be measured. The measured values are compared with theoretical values, which serve as basis for the design of the device and which are stored in the measuring device 10. In case of deviation beyond the predetermined tolerance width, the correction value is generated and stored. The transistors Tx to T4 can each consist of several individual transistors connected in parallel, where the individual transistors are connected in accordance with the correction value. For example, the individual transistors can be connected directly to the individual memory cells of a memory which is not shown, in which the correction value is stored as a binary value. The correction value in this case determines the number of the individual transistors, which are arranged parallel to each other and are activated according to the correction value. The memory can in this case be contained in the oscillator 7, through which the antenna 3 is then activated in accordance with the correction value. The oscillator 7 then acts as a phase for driving the current of the antenna 3. The transistors T: to T4 in the bridge circuit can also be activated by means of a signal modulated in the width of the pulse through the oscillator 7. Depending on the length of the switching pulse and a pause of the following variable pulse (pulse duration and pause depend on the correction value), the pairs of transistors T1 and T3 or T2 and T4 are switched on and off for a period of time. different time. In this way, the current I through the antenna 3 can be activated as a function of the correction value.

The activation with a signal modulated in the pulse width has the advantage that at the same time a signal modulated in the amplitude can be transmitted to the transponder 2. The excitation current and, therefore, the current I through the antenna 3 is modified, however, only within a predetermined tolerance width as a function of the correction value. If a major modification is necessary, then it can be deduced that the corresponding transceiver 1 is affected by too large errors and separated accordingly. In the device according to the invention, the correction value is set at least once after the manufacture of the transceptor 1 at the end of the tape. In all subsequent transmission processes, the correction value is already included, so that the performance of the transmission is high, that is to say, therefore the received amplitudes of the transmission signals are sufficiently large. The correction value can be determined in the device according to the invention when the transponder 2 is arranged in the vicinity of the transceiver 1. The oscillating circuit of the transponder 5, 6, however, only has a small effect on the resonance frequency fR. of the oscillating circuit of the antenna 3, 4 and on the current I through the antenna 3, since its coil 5 and its capacitor 6 only have reduced impedance values by virtue of the reduced dimensions of the transponder 2. For this reason, the resonance frequency fR of the oscillating circuit of the antenna 3, 4 and the current I through the antenna 3 are also determined without the transponder 2. The theoretical values for the resonance frequency fR and the current Ix can be determined previously in a laboratory model. But the theoretical values can also be calculated with the help of a model. More advantageously, a device according to the invention is used in an anti-theft system for a motor vehicle. In this case, energy is transmitted from the transceiver 1 to the transponder 2, which uses this energy to retransmit encoded data from the transponder 2 to the transceiver 1. More advantageously, the oscillation of the oscillating circuit of the transponder 5, 6 is modulated in the load and in the frequency to the rhythm of the encoded information. Due to the inductive coupling, the oscillation of the oscillating circuit of the antenna 3, 4 is also modulated. The modulated oscillation of the oscillating circuit of the antenna 3, 4 is detected either by the measuring device 10 or by an evaluation unit not shown . A demodulator demodulates the encoded information from the modulated oscillation and transmits it to a comparator. The comparator compares the detected encoded information with a theoretical encoded information and emits in case of coincidence a release signal to a security equipment. A safety device of this type can be, for example, a gear lock or a door lock. The transceiver 1 can be arranged in this case in a door lock or ignition lock, while the transponder 2 is mounted in an ignition key or a chip card. The measuring device 10 can be a microprocessor, which detects the current through an A / D converter and assumes the additional connection of the capacitance C and / or the inductance L or the control of the excitation current. The microprocessor can assume other functions, such as demodulation and comparison. Instead of the amplitude of the current, the amplitude of the voltage in the antenna 3 can also be measured. For the measurement of the angle of the phases and of the capacitances or the inductive detuning of the oscillating circuit of the antenna, the phase of both the the voltage as well as the current through the antenna 3. Such measurements are sufficiently known. Therefore, it is not necessary to treat them here in detail. The capacitive and / or inductive network 11, through which the capacitance? C or the inductance? L of the oscillating circuit of the antenna 3, 4 is connected as a parallel or series impedance, consists of different impedances, such as capacitors and coils. The magnitude of the impedance, which modifies the oscillating circuit of the antenna 3, 4 depends in this case on the de-tuning of the oscillating circuit of the antenna 3, 4 and, therefore, of the resonance frequency fR and the frequency of excitement fr

Claims (7)

1. CLAIMS 1. Device for the transmission of data or power supply from / to a transponder, especially for an anti-theft system in a car, with a stationary transceiver (1), which has a first oscillating circuit (3, 4) with an antenna (3) in the form of a first coil and a first capacitor (4), where the resonance frequency (fR) is determined through its components, a portable transponder (2), which has a second oscillating circuit (5) , 6) with a second coil (5) and a second capacitor (6), and an excitation unit (7), which oscillates with an oscillator frequency (f0) and whose output variable is used as an excitation variable with an excitation frequency (fE) for the generation of an oscillation of the first oscillating circuit (3, 4), and - an evaluation unit (10), in which the current (I) and / or the voltage (U) is measured in the first oscillating circuit (3, 4) and in which in case of a deviation With the aid of the current or the voltage with respect to a theoretical value, a correction value is generated, with the help of which the first oscillating circuit (3, 4) is then corrected in all transmissions between the transceiver (1) and the transponder (2), with which a transmission as effective as possible between the two takes place.
2. 2. Device according to the claim 1, characterized in that the current (I) and / or the voltage (U) is measured in the first oscillating circuit (3, 4) according to the amount and phase () and because the value of correction.
3. 3. Device according to the claim 2, characterized in that the resonance frequency (fR) of the first oscillating circuit (3, 4) is modified as a function of the correction value by approaching or moving away from at least one inductivity in series or in parallel (? L) and / or at least one capacity in series or in parallel (? C) with respect to the antenna (3) or with respect to the first capacitor (4).
4. 4. Device according to the claim 2, characterized in that - the excitation unit (7) has a drive phase, which is controlled as a function of the correction value, whereby the current increases or decreases in the first oscillating circuit (3, 4), because the correction value is stored in a memory of the drive unit (7), and because the memory is connected to the drive phase. Device according to claim 4, characterized in that the current (I) in the first oscillating circuit (3, 4) is modified through the correction value only within a predetermined tolerance amplitude. Device according to claim 1, characterized in that the first oscillating circuit (3, 4) is coupled inductively with the second oscillating circuit (5, 6) through the antenna (3) and the second coil (5), when the transponder (2) is in the vicinity of the transceiver (1). Device according to claim 6, characterized in that the transponder (2) has a coded information, which due to the inductive coupling has a modulated oscillation of the first oscillating circuit (3, 4), - because the modulated oscillation is detected by the evaluation unit (10), because the encoded information is demodulated from the modulated oscillation, because the detected encoded information is compared with a theoretical encoded information and because in case of coincidence, a release signal is generated for the release of a safety equipment.