EP0153498A2 - Remote-controlled door locking system for automotive vehicle - Google Patents

Abstract

In the door-locking system there is a small transmitter which can be transported and actuated by the driver and which emits electromagnetic radiation. In the motor vehicle there is at least one receiver which receives the electromagnetic radiation and which triggers the actuation of the door lock. The small transmitter comprises a memory (diode matrix 3) for a code and a modulator (encoder 1, flank modulator 9, transmission stage 16) for modulating the electromagnetic radiation by means of the code. In the receiver there are a reception part receiving the modulated radiation, a demodulator (monostable multivibrator 20, D-flip-flop 21) and a comparator (28) comparing the demodulated code with a code stored in a code memory. An actuator (31) for the lock is connected operatively to the comparator. The transmitter contains the modulator for modulating the radiation with a pulse-code/pulse-position modulation (PCM/PPM). Corresponding to this in the receiver is a demodulator for demodulating the PCM/PPM-modulated radiation. <IMAGE>

Description

The invention relates to a device for contactless, remote-controlled door locking, in particular central locking of motor vehicles, according to the preamble of claim 1.

Such known devices are increasingly being used in practice since they have considerable advantages over fine mechanical means for locking a door with a key and also over conventional electromotive, pneumatic or hydraulic central locking systems. Laborious manipulations to insert the key into an unlit lock are no longer necessary. Rather, a vehicle can be conveniently unlocked when the transmitter is approximately aligned with the receiver. In addition, such wireless remote-controlled door locks enable an even greater security against unauthorized unlocking with "duplicate keys, aa with reasonable effort a very large number of coding possibilities can be realized. - The contactless transmission of the code for unlocking, but also for locking doors, more precisely a coded word consisting of a large number of bits can be done with electromagnetic vibration in the megahertz or gigahertz range, particularly advantageously also by infrared radiation (DE-OS 29 11 828).

The modulation of the electromagnetic carrier has a significant influence on the properties of the device for contactless, remote-controlled door locking. So you can think of modulating the carrier with the coded word pulse duration by assigning the different logical meaning of each bit (high or low) to a pulse of different lengths. This creates a pulse train or a pulse of permanently modulated pulses. A disadvantage of this type of modulation is the relatively large power consumption of the transmitter, in particular of the transmitter stage, which generates the electromagnetic radiation. This causes a relatively rapid consumption of the batteries, which should be as small and compact as possible, and a corresponding power loss in the transmission stage, which in turn requires the use of correspondingly powerful components.

It is also possible to modulate the electromagnetic radiation with the coded word in pure pulse code modulation. (Possibly similar to DE-OS 29 09 134). With this code method, the word is represented with impulses of the same amplitude, shape and position in time. It is significant with this coding whether a pulse on a certain place of the pulse or at a certain time is present or not. In order to detect this condition in the receiver, the detection circuit will be relatively complex.

Furthermore, it belongs to the prior art (DE-OS 26 04 188) to transmit the coded word and a transmitter clock by means of pulses of two different frequencies. The distance between the pulses contains the clock signal, while the frequency of the oscillation characterizes the logic level of the respective bit during the pulse duration. The facility working on this principle is relatively complex. The transmitter requires, among other things, switchable oscillators, the frequencies of which must be kept sufficiently stable. In particular, frequencies of 28 and 35 kHz have been chosen for the operation of an ultrasonic oscillator as a transmitter, instead of a transmitter of electromagnetic radiation. The oscillator is controlled by a switch, which in turn is operated by a clock generator. The switch switches the serial output of a parallel series converter (shift register), which is fed with a hard-wired word at its parallel inputs. - In the receiver, the signal received by an ultrasound microphone is first amplified and then fed to a phase-locked loop circuit and decoded with a control logic. The decoded code levels are in turn fed into a converter which acts as a series parallel converter. It compares the content of the converter at parallel outputs with a code, which is in turn stored, and actuates an actuator of the locking device when the comparison is made. - Apart from the relatively complex signal processing here, especially in the Decoding, a relatively large amount of energy is still required for the wireless transmission of the code word, albeit less than in the case of pulse duration modulation.

The present invention has for its object to develop a device for non-contact remote-controlled door locking, in particular a central locking of motor vehicles, according to the preamble of claim 1, that the disadvantages of the corresponding known devices are avoided, that is, with the device a coded wireless Pulse can be generated with low circuit complexity and, above all, low energy consumption. The coded pulse should be able to be transmitted wirelessly with a high level of interference immunity and in turn should be precisely decodable in the receiver without great circuitry complexity. With low energy requirements, the focus is on a good ratio of the wirelessly transmitted useful signal to possible interference signals. As a result of the low energy consumption of the transmitter, it should be able to be compact and require little maintenance.

This object is achieved by the invention specified in the characterizing part of claim 1.

According to the invention, the coded word, which is transmitted by the electromagnetic radiation, preferably infrared radiation, is modulated on the carriers by pulse position modulation (PPM). Each bit of the word is thus transmitted by a unit pulse of relatively short duration, which is more or less distant in time from another predetermined pulse according to the logic level of the bit. These two standard pulses practically mark the beginning and end of a permanently modulated pulse, which, however, is not transmitted between the pulse edges. Accordingly, the contact-free transmission of the modulated electromagnetic radiation in the case of infrared radiation takes place by means of short flashes of light, which represent the unit symbols. In this context, short means a substantially shorter period of time than the lengths of a pulse duration modulated pulse from which the unit pulses at the beginning and end are derived.

The transmission method results in considerable current savings, since the current required to form the electromagnetic radiation can be up to a factor of 100 lower than in the case of burst modulation. Due to the pulse position modulation instead of the pulse duration modulation, the transmission stage, in particular a transmission diode for emitting infrared radiation, is also loaded with less power loss. With the same power requirement of the transmitter, the useful signal can be increased compared to the noise signal. There is more accurate pulse demodulation in the receiver than in the case of pulse duration modulation Pulse possible because the decoding can be triggered each time by the same pulse edge (rising or falling) and not by alternately rising and falling pulse edges as in the case of pulse duration modulation

In particular, no fast receiver diodes and operational amplifiers are required in the receiver for leading edge triggering.

Particularly expedient designs of the transmitter and the receiver for modulating or demodulating the radiation with the pulse code-pulse position modulation are specified in claims 2 to 8.

Claim 2 contains little complex means in the transmitter to form a time sequence corresponding to the code word to be transmitted pulse duration modulated pulses, a corresponding sequence of pulse position modulated, short unit pulses.

Claim 3 specifies how a sequence of 2n pulse duration modulated pulses can be formed with an encoder which has n parallel inputs which are connected to n powers of a code memory. This significantly increases the variety of possible code words and thus significantly increases security against unauthorized unlocking with little additional effort.

Details of how a corresponding sequence of pulse position-modulated short unit pulses can be exactly formed from the sequence of pulse duration modulated pulses in a less complex manner are given in claim 4.

An alternative to the edge modulator according to claim 4 represents claim 5.

A safety circuit is particularly advantageously provided in the receiver, which detects the unit pulse assigned to the beginning or the end of a pulse duration modulated pulse of a bit and helps to prevent unlocking due to incorrect pulses occurring in the transmission path. According to claim 6, the transmitter further comprises measures which also supply the first received unit pulse of a pulse for comparison with the code stored in the receiver. The first unit pulse is therefore not lost to the evaluation of the transmitted code word despite the safety circuit.

Claim 7 specifies the arrangement of a delay element in the signal flow direction of the received unit pulses before a D flip-flop, which carries out the conversion of two successive unit pulses into a pulse-duration-modulated pulse.

Instead of this delay element in the forward branch, an evaluable, permanently modulated pulse can also be obtained from the first short unit pulse by an art circuit at the output of the D flip-flop and at the output of the mon flop provided according to claim 6. - The evaluation is therefore never supplied with a short needle pulse which could falsify the recognition of the transmitted coded word.

An additional monostable multivibrator according to claim 8 is used for pulse formation from the received unit pulses in such a way that by an edge (the trailing edge) These unit pulses generate particularly short needle pulses which trigger the monostable multivibrator to set the D flip-flop. The latter monostable multivibrator and the D flip-flop form the fuse circuit.

• Fig. 1 - ein Blockschaltbild des Senders zur Aussendung einer Infrarotstrahlung;
• Fig. 2 - eine schaltungstechnische Realisierung des Senders nach Fig. 1;
• Fig. 3 - Zeitverläufe der in dem Sender erzeugten Pulse:
• Fig. 4 - Zeitverläufe der Pulse in einem Abschnitt des Senders, nämlich dem Flankenmodulator und
• Fig. 5 ein vereinfachtes Schaltbild des Empfängers.

The invention is explained below with reference to a drawing with five figures. It shows:

• Fig. 1 - a block diagram of the transmitter for emitting infrared radiation;
• Fig. 2 - a circuit implementation of the transmitter of Fig. 1;
• 3 - Time profiles of the pulses generated in the transmitter:
• Fig. 4 - time curves of the pulses in a section of the transmitter, namely the edge modulator and
• Fig. 5 is a simplified circuit diagram of the receiver.

In Fig. 1, 1 denotes an encoder, to the parallel inputs 2 of which a diode matrix 3 is connected. A series output of the encoder is labeled 4.

As can be seen in detail from FIG. 2, the encoder comprises twelve parallel inputs 2, which are connected to a corresponding number of lines, for example five of the diode matrix. The diode matrix comprises a left branch of any insertable diodes 6 and a right one Branch of diodes which can also be inserted as desired. The left branch and the right branch each represent a code ⁼ partial memory. Twelve bits can be programmed in each partial memory. The logic level of each bit - 0 or 1- depends on whether or not there is a diode in the line assigned to the bit, for example 5.

The left branch and the right branch can be activated alternately by a multivibrator 8.

In the preceding circuit arrangement, the En.coder generates a sequence of pulses, which for each of the two possible switching states of the multivibrator comprises twelve bits or permanently modulated pulses. The pulse duration depends on the logic level, with logic 1 being assigned a short pulse duration and logic 0 being assigned a long pulse duration. The pulse duration is in turn determined in that a diode in the left or right branch is assigned to a corresponding parallel input of the parallel inputs 2 or not.

This sequence of pulses is shown with the pulse a in a first time interval for the left branch of the diode matrix and the pulse b during a subsequent second time interval for the right branch of the diode matrix. The entire word thus consists of 24 bits corresponding to a sequence of 24 permanently modulated pulses. In the representation of the pulses a and b in Fig. 3 it is assumed that the one branch, e.g. 6, the diode matrix in Fig. 2 is completely covered with diodes, while the other branch, e.g. 7, has no diodes.

The pulse permanently modulated with the coded word during the first and second time interval is converted with the edge modulator into a pulse position-modulated pulse, which is thus also modulated in accordance with the coded word. A pulse is thus generated in the edge modulator 9, in which relatively short unit pulses at the beginning and end of a permanently modulated pulse on the series output 4 mark the logic level of this permanently modulated pulse. The individual impluses occur on an output line 10.

The pulse c in FIG. 3, which represents a temporally stretched section of the pulse b, serves to illustrate the pulse generated in the edge modulator. Pulse c is assigned the pulse d consisting of short unit pulses on the output line 10 in FIG. 1.

As can be seen from FIG. 2, the edge modulator 9 comprises two exclusive NOR gates 11 and 12, of which the exclusive NOR gate is only connected as a negation point. The exclusive NOR gate 12 receives a pulse duration modulated pulse from the series output 4, which is designated as Y ₁ in FIG. 4. A second input of the exclusive NOR gate 12 receives an inverted - exclusive NOR gate 11 - and delayed - delay element 13 - pulse Y ₂ . The exclusive NOR gate 12 then only forms a short pulse Y ₃ on the output line 10 if either the pulse Y ₁ or the pulse Y ₂ is present.

With these unit pulses Y ₃ , an IR diode 15 is activated via a TMOS transistor 14, so that this emits short infrared light flashes corresponding to the unit pulses Y ₃ .

The TMOS transistor 14 essentially forms the transmission stage 16 in FIG. 1.

It is noted that in Fig. 1 the transmitter and the infrared diode itself belong to the modulator which modulates the emitted infrared light.

The circuit arrangement of the small transmitter discussed so far is fed by a power supply part 17 with a voltage converter 18. A circuit implementation of the power supply and the voltage converter is shown in Fig. 2 within the broken lines. The voltage converter supplies two button cells, which form the power supply 17. a voltage of approximately 9 volts for the encoder and the exclusive NOR gates. The IR diode 15 can also be supplied with the relatively low voltage, since the TMOS transistor is selected for its activation. This also forms a current limiting resistor, so that no additional means for limiting current when heat is required.

Reference is made to FIG. 5 to discuss the receiver, which can be arranged in a vehicle for contactless door locking and unlocking. 5 shows an essential part of the receiver. It is assumed that in a receiving part, not shown, which is connected to an input line 19, the received infrared light impulses are converted into appropriately shaped electrical impulses and amplified. Pulses therefore occur on the input line 19, the shape and course of which essentially correspond to the pulse d in FIG. 3.

A demodulator designed as a safety circuit with a monostable multivibrator 20, which has a dynamic input, and a D flip-flop 21 are provided to demodulate this sequence of unit pulses. With a timer 22, the monoflop time of the monostable multivibrator 20 is set so that it is at least twice as long as the pulse length for two bits. An output of this monostable multivibrator is connected to a set input S of the D flip-flop. The reset input R is grounded. A negated output of the D flip-flop Q is fed back to a static input D in the usual way. The D flip-flop practically acts as a frequency divider.

For the safe operation of the circuit arrangement, a further monostable multivibrator 23 is connected upstream of the monstable multivibrator 20. However, a timer 24 on the further monostable multivibrator generates a needle pulse, which is even shorter than the unit pulse, at the output Q of the further monostable multivibrator 23. This monostable multivibrator generates a needle pulse each time the negative edge of a standard pulse occurs on its. dynamic input. The monostable multivibrator 20 is triggered with the needle pulses, which cannot normally fall back due to the dimensioning of the timing element 22, since it is triggered again each time beforehand. Accordingly, it is at the set input S of the D flip-flop with a proper pulse train on the input line 19 to a signal which sets the D flip-flop in preparation. Each time a pulse occurs at the dynamic input of the D flip-flop in the course of a pulse consisting of the unit pulses on the input line 19, this is switched over, with the result that a pulse-width-modulated rectangular pulse occurs again at the output Q. Accordingly, the input pulse at the dynamic input of the D flip-flop can be viewed as pulse y3 in FIG. 4 and the output pulse at output Q as y 1 in FIG. 4. Thus, the received light pulse is demodulated.

Through a delay element 25, which is connected upstream of the dynamic input of the D flip-flop, the standard pulses only reach the input when the set input S is prepared. This means that no standard pulse for switching the permanently modulated rectangular pulse at output Ö can be lost.

The output Q is coupled to a series parallel converter 26, the parallel outputs 27 of which are led to a comparator 28. The permanently modulated rectangular pulse generated in the D flip-flop is thus compared in the comparator with a code word which is stored in a code memory 29. If the comparison is successful, an actuator 31 is made via a pulse shaper 30. Unlocking or locking triggered and the converter 26 reset via a line 32 at the same time.

It is also noted that, for safety reasons, the circuit of the receiver can be designed in such a way that two to three matching pulses must first be received before the actuator 31 is activated.

Claims (8)

1.Device for non-contact remote-controlled door locking, in particular central locking of motor vehicles, with a small transmitter which can be transported and operated by the driver and which emits electromagnetic radiation and which has a memory for a code and a modulator for modulating the electromagnetic radiation with the code, and with at least one a receiver arranged in the motor vehicle, which comprises a receiving part receiving the modulated radiation, a demodulator, a comparator which compares the demodulated code with a comparator stored in the receiver and which is connected to an actuating element of the lock,
characterized,
that the modulator (encoder 1, edge modulator 9, transmitter stage 16) for modulating the radiation with a pulse code pulse position modulation (PCM / PPM) and the demodulator (monostable multivibrator 20, D flip-flop 21) for demodulating the PCM / PPM modulated radiation are set up. 2. Device in which the small transmitter has an electronic encoder, the parallel inputs of which are connected to the memory of the code and the series output of which is connected to the modulator according to claim 1,
characterized,
that the encoder (1) is designed to generate a sequence of pulse duration modulated pulses corresponding to the code at the parallel inputs, that an edge modulator (9) is connected to its series output (4) is, which is set up to generate a short unit pulse on at least one 'edge of the pulse duration modulated pulse, the position of which is modulated, and that a transmission stage (16) is coupled to the output (line 10) of the edge modulator (9). 3. Device according to claim 2,
characterized,
that with the parallel inputs (2) of the encoder (1) two code partial memories (left branch 6 and right branch 7 of the diode matrix 3) can be switched alternately in a controlled manner by a multivibrator (8). 4. Device according to claim 2 or 3,
characterized,
that the edge modulator (9) has at least one exclusive NOR gate (12) with two inputs, one input of which is connected directly to the serial port (4) of the encoder (1) and the other input of which is via a negation element (exclusive NOR Gate 11) and a delay element (13) with the series output (4) is connected. 5. Device according to claim 2 or 3,
characterized,
that the edge modulator consists of a Schmitt trigger, the trigger input of which is coupled to the series output of the encoder. 6. Device according to claim 1,
characterized,
that the demodulator of the receiver has at least one monostable multivibrator (20) with a dynamic input comprises, which is fed with short unit pulses of a transmitted pulse sequence or with needle pulses formed from them, that the monstable flip-flop is dimensioned for a monoflop time (timer 22) which is at least twice as long as the maximum period of the unit pulses that the output Q the monostable multivibrator is connected to a set input (S) of a D flip-flop (21), the dynamic input of which can be acted upon by the standard pulses and whose output (Q) which emits a pulse duration modulated pulse with a converter connected to the comparator (28) ( 26) is connected and that delay means (delay element 25) are provided for forming the first pulse of the pulse duration modulated pulse. 7. Device according to claim 6,
characterized,
that a delay element (25) is connected upstream of the dynamic input of the D flip-flop (21) as a delay means. 8. Device according to claim 6,
characterized,
that the monostable multivibrator (20) is preceded by another monostable multivibrator (23), the dynamic input of which can be controlled by negative edges of the short unit pulses to form the needle pulses.

Images