WO2003071067A1 - Electronic control circuit comprising a proximity sensor and a transceiver for a vehicle door locking system - Google Patents

Abstract

Disclosed is an electronic control circuit for a car door locking system, comprising a control unit with an induction coil, which transmits a data inquiry to an external contactless data carrier and causes the car door locking system to be unlocked if said data carrier receives a valid response. The inventive electronic control circuit also comprises a proximity sensor with at least one proximity electrode, which triggers the transmission of the data inquiry when a person approaches the proximity electrode. The proximity electrodes and the induction coil are mounted in the outer door handle of a car. The inventive electronic control circuit is also provided with an electrostatic shield between the proximity electrode and the induction coil.

Description

 Electronic control circuit with a proximity sensor and a transceiver for a vehicle door locking system

The present invention relates to an electronic control circuit for a car door locking system and a car door handle with such a system. The present invention also relates to a car door handle with a cavity in which an electronic control circuit is housed.

In such a car door locking system, a car door locking system is unlocked by means of an electronic control circuit integrated in the car door handle, that is, from a state that prevents opening of the door or flap to a state that enables opening of the door or flap.

In the case of locking systems of the type mentioned above, it is already known to give a person access to a car by querying data from a contactless portable data carrier (for example in a chip card or in a key fob). The data query is triggered by a mechanical switching element, or by a proximity sensor, which triggers the forwarding of a data query to the external portable data carrier when a person approaches the handle. The data carrier (for example a transponder) is "woken up" by the received data query and answers it by sending an identification message to the control circuit. The control circuit only releases the door when the identification is valid.

Proximity sensors that use an infrared or ultrasound sensor system are known. They have the disadvantage of being very sensitive to dirt or external noise. Microswitches and pressure sensors have also been used, but they react late (when the user actually touches the handle). This delayed data query and the subsequent reaction time of the unlocking mechanism make such systems uncomfortable. In some cases, this means that the locking system at the first Actuation of the handle is not yet unlocked and the person requesting access has to touch the handle again to unlock the door.

WO9741322 describes a system in which at least one electrode is installed in the handles and a counter electrode is attached in the part of the door opposite the handle. An electrical field is built up between the two electrodes, which is used to determine the access request of a person reaching for a handle. As soon as a hand is between the handle and the opposite part of the door, a data query is sent to the external data carrier. To send the data request, an electromagnetic transmitter-receiver with an induction coil is used in this system. The proximity sensor electrodes are formed by the induction coil and / or by the chrome-plated cover of the handles.

However, this system has the disadvantage that it only reacts when a hand comes between the handle and the opposite part of the door, so only insignificantly before touching the handle.

Systems are also known in which capacitive proximity sensors are used in order to sense the access request of a person reaching for a handle before the contact between the hand and the handle. Such systems measure the capacitance between an electrode in the handle and the earth. When a person approaches the electrode, this capacity is changed, which can trigger a signal to send a data request. If such an electrode is installed in the immediate vicinity of the electromagnetic transceiver, it is disturbed by the voltage and / or charge changes in the transceiver, so that incorrect attempts at approach are determined and unwanted power-consuming data queries are triggered. This problem is mostly solved by keeping the sensitivity of these systems low, which has the disadvantage that they are only shortly before being touched react to the handle, or by mounting the proximity sensors as far as possible from the transmitter-receiver, which is not possible in a small handle (for example in a pull handle).

An object of the present invention is to improve the reliability of such a system.

It has been found that such locking systems prove to be insufficiently robust. In particular, the reliability of the hand sensing depends on the condition of the proximity sensor electrodes. Dirt, water, snow, scratches or dents affect the capacity between the electrode in the handle and the electrode in the door. In some cases, this means that unwanted data queries are triggered or, conversely, that approaching hands are sensed too late, or under certain circumstances only after several attempts. It has also been found within the scope of the invention that the proximity sensor electrodes are disturbed by the induction coil and that disruptive charges arrive on these electrodes when a data query is sent, so that the capacitance between the proximity sensors and the earth is measured incorrectly.

Another object of the present invention is to solve these problems and to offer an electronic control circuit which is less sensitive to scratches, dirt, water and electrostatic disturbances, in particular disturbances from the induction coil.

These goals and other advantageous properties result from an electronic control circuit according to the claims. In particular, these problems are solved by an electronic control circuit for an auto door locking system, which contains the following features: a control unit with at least one induction coil in order to forward a data query to an external contactless data carrier and to trigger the unlocking of the auto door locking system if a valid response is received from the named data carrier, a proximity sensor with at least one proximity sensor electrode to initiate the forwarding of said data query when a person approaches said proximity sensor electrode, said proximity sensor electrodes and said induction coil being housed in the exterior door handle of a car, an electrostatic shield between said proximity sensor electrode and said induction coil.

This has the advantage that electrostatic charges and / or electrical voltages on the induction coil do not or at least significantly impair the proximity sensor electrode, so that the capacitance between the proximity sensors and the earth is correctly determined. Thanks to this electrostatic shielding, an approaching person can be reliably sensed and, if necessary, immediately after a data request has been sent by the induction coil.

This also has the advantage that a very sensitive proximity sensor can be used which can sense a person requesting access very early on and whose electrodes can be covered by a housing and / or a sprayed material, which provides additional protection against scratches, Allows dirt, water, damage and dents.

Preferred exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings. Show it:

Fig. 1 shows the handle of a pull handle and part of a vehicle door in cross section.

Fig. 2 shows the control circuit shown in perspective

Fig. 3 is a schematic of the electronic control circuit. Fig. 4 is a perspective variant of the control circuit

In FIG. 1, 7 shows a vehicle door pull handle, which comprises an inner part 9 fastened to the vehicle door and a handle 7 designed as a bow handle. The handle 7 comprises a handle dome 70 which, with the end facing away from the handle 7, projects into the interior 90 of the vehicle door and is connected to the automatic door locking system, which is not shown for reasons of clarity. The auto door locking system is unlocked via the vehicle central locking system in order to free the handle dome 70 and thus the handle 7. In the released state, the handle 7 can be pulled outwards to open the vehicle door. For this purpose, the handle 7 can be rotated about the joint 71 shown. As a variant, the door could open automatically after recognition of a valid identification of the person requesting access.

In the handle 7 there is a cavity 72 in which the electronic control circuit 1 is accommodated, which is intended to enable the authorized user to trigger the unlocking of the car door locking system in the most convenient way possible. The control circuit 1 is connected to the auto door locking system inside the vehicle by connecting cables 12. It is preferably powered by these connecting cables from the car battery. In the event of a power failure, the door can preferably be opened by means of a locking cylinder (not shown) with a key provided for such cases.

The control circuit includes a touch sensor 22 which is a

Signal triggers as soon as the user places a finger (especially a thumb) on the outer side of the handle. A proximity sensor 5 triggers another signal when a hand or another earthed object approaches, in particular in the case of a hand approaching the space between the handle 7 and the inner part of the handle 9. As explained later, these signals are transmitted by a control unit 20 with a microcontroller and at least one induction coil 3 interpreted to forward a data query to an external contactless data carrier, not shown.

The data carrier preferably consists of a transponder (which can be integrated, for example, in a chip card or in a key holder) and is "woken up" by this data query. If the data query is addressed to him, he responds with a response that includes an identification of the data carrier or that is signed with such an identification. The response is received by the electronic control unit 20 in the handle 7 in order to trigger the unlocking of the car door locking system if it contains the expected identification or if it was signed with this expected identification. In a further embodiment, the control unit 20 is only partially embedded in the handle 7.

The control circuit 1 is described in more detail in connection with FIGS. 2 and 3. It comprises a printed circuit board 2 on which all components 20, 21, 22, 3,4,5, 120 are mounted. The circuit board 2 preferably has a thickness of 0.3 mm or less, but preferably of 0.2 mm or less, and is therefore flexible and less prone to breakage. It is housed in a synthetic insulating housing 13, which longitudinally fills most of the cavity 72 in the handle 7.

The control unit 20 is mounted on the left-hand side of the printed circuit board 2, which comprises a plurality of electronic SMD components, including a microcontroller, mounted by a so-called reflow process. The connecting cables 12 are mounted parallel to the printed circuit board 2 on the right side thereof by the so-called auto-splice method. The main advantage of the Autosplice process compared to other soldering or fastening processes is that it is much less sensitive to shocks, vibrations and changes in temperature. A synthetic seal 121 (made of Santoprene or other elastomer, for example) holds the cables 120 in place and prevents moisture infiltration into the housing. The control circuit 1 also includes a contactless transmitter-receiver in order to exchange data with the external contactless data carrier. In the preferred variant shown, the contactless transceiver comprises a resonance circuit with an induction coil 3 and a capacitor 4, which are mounted directly on the printed circuit board 2, as shown schematically in FIG. The induction coil consists of a winding of an electrically insulated wire on a plate-shaped ferromagnetic ferrite core. The capacitance is preferably a ceramic or polypropylene capacitor with a value of approximately 3.3nF to 18nf, but preferably approximately 15 to 18nF. It is used to match the impedance of the transceiver to the driver stage of the microcontroller.

The control circuit 1 also includes a proximity sensor with two proximity sensor electrodes 5 in this preferred example in order to sense people who are approaching the handle. The proximity sensor electrodes 5 are electrically connected to the control unit 20 such that the changes in capacitance between the proximity sensor electrodes 5 and the earth caused by the user body are sensed. When a (grounded) person approaches the proximity sensor electrodes 5, the capacitance between these electrodes and the earth is impaired. The control unit 20 preferably determines these small changes in capacity using a charge transfer measurement system, i.e. by switching the unknown capacity with a larger reference capacity via switches.

The electrodes 5 each consist of a long, flat, electrically conductive plate on the upper side of the printed circuit board 2 or preferably along this printed circuit board. In this way, the movement of a hand between the bow-shaped outer part 7 of the handle and the vehicle door can be determined quickly and reliably.

According to the invention, an electrostatic shield 21 is provided between the proximity sensor electrodes 5 and the induction coil 3. This shielding prevents, among other things, that the Measurement of the capacitance between the proximity sensor electrodes and the earth is disturbed by the induction coil 3 and that parasitic charges reach the sensitive proximity sensor electrodes 5. Since this interference factor is eliminated or at least significantly suppressed by the invention, the sensitivity of the proximity sensor can be increased without increasing the risk of incorrect proximity determinations.

In the preferred example shown, the shield consists of two electrically conductive metal plates 21 which separate the induction coil 3 from the two lateral proximity electrodes 5. The plates 21 are mounted perpendicular to and directly on the printed circuit board 2. They are preferably electrically connected to the ground of the circuit 1. If the available space, in particular the permitted height, allows it, the shielding could be made even more efficient; in particular, the circuit board could also be used as a shield.

FIG. 2 shows a touch sensor 22 which is mounted on the printed circuit board 2 in such a way that contacts between the hand, in particular the thumb, the user seeking access to the vehicle and the outside of the handle can be determined (on this figure on the left side of the printed circuit board 2). In the preferred example shown, the touch sensor contains a capacitance with an electrode on the outward-facing side of the printed circuit board 2 and another electrode on the inner side of the printed circuit board, which can consist, for example, of the basic interconnects on the assembled side of the printed circuit board. The capacitance of the touch sensor is preferably less than 5pF. The touch sensor also contains a capacitance measurement system to determine the capacitance changes caused by the user finger and to direct them to the named microcontroller.

The control unit 20 and the touch sensor 22 are connected to the transmitter-receiver circuit and to the connecting cables 12 via conductor tracks on the printed circuit board 2. These paths run under the induction coil 3, possibly also on the other side of the circuit board and / or through inner layers.

The circuit board 2 is accommodated in a synthetic housing 13 which extends substantially through the entire length of the cavity 72 in the handle part 7. The housing 13 and the proximity electrodes 5 are preferably slightly curved in order to adapt to the bowed shape of the handle part 7. Since curved ferrite cores are expensive and since problems with wire winding on a bow-shaped core can arise, only the two ends of the housing 13 are preferably curved, as can be seen in FIG.

In a further embodiment, the core of the coil and thus the entire coil 3 is flexible. Since the circuit board is preferably so thin that it also has a certain flexibility, the adaptation of the control circuit to the bowed shape of the handle part 7 is considerably simplified. In addition, a flexible magnetic core is less breakable than a ferrite core. The reliability of the control circuit is thus significantly increased by reducing its sensitivity to the bumps that are unavoidable in a car door. For example, the flexible core consists of several thin, flexible layers of magnetic material that are held together with flexible fasteners. In a further embodiment, the magnetic core is formed from an amorphous magnetic material, that is to say from a flexible casting compound in which small particles of a material with high permeability, such as ferrite particles, are cast. In a still further embodiment, the magnetic core is in several parts. For example, it consists of several smaller parts made of a possibly hard magnetic material such as ferrite, which are connected together with a preferably magnetic flexible material.

The circuit board 2 with all components is encapsulated in a thermoplastic insulating material which is injected into the cavity and which protects the components from moisture and dirt. For example, a "hot melt" material (for example Macromelt) can be used, which is sprayed at a temperature of approximately 215 ° degrees and at low pressure.

Since the material is sprayed and not simply cast, you can control the thickness of the material precisely and benefit from the greater thickness of the handle7 in the middle. The thickness of the sprayed material along the longitudinal axis is therefore greater than at the two longitudinal edges in order to reinforce the structure where there is more space in the handle. It is also possible to reduce the thickness of the spray material above the electrodes 22 and 5 in order not to reduce their sensitivity.

FIG. 4 shows a variant of the control circuit in which the proximity electrodes 5 are designed as part of the printed circuit board 2. In the example shown, a longitudinal cut is cut on both sides of the circuit board 2 not far from the two edges. When the flexible circuit board is bent to be mounted in the housing 13, the two separate lateral strips on the edge of the circuit board rise above the level of the circuit board. A longitudinal electrically conductive path is provided on each strip separated in this way, which is connected to the control unit 20 and acts as a proximity sensor electrode.

In this example, the electrostatic shielding between the proximity electrodes on the two strips and the induction coil 3 is carried out by two electrically conductive metal plates 21 which are mounted perpendicular to the printed circuit board 2. However, it would also be possible to produce this shielding by means of an interconnect electrically connected to the earth on the inside of each lateral strip of the printed circuit board 2. In this variant, not shown, there are at least two interconnects on each cut edge of the circuit board: the outer interconnect acts as a proximity sensor, while the inner interconnect, which is connected to the ground, serves as an electrostatic shield between this sensor and the induction coil. The distance between everyone Proximity sensor electrode and the corresponding shielding interconnect is considerably smaller than the distance between the electrodes and the ferrite core, so that the capacitive influence of the ferrite core on the proximity electrode only plays a minor role.

It would also be possible to provide the shielding interconnects connected to the ground on the other side of the printed circuit board 2.

Although the entire description relates to a vehicle pull handle, it will be understood that this invention is also applicable to other types of vehicle exterior door handles, particularly handle flaps.

Claims

Expectations 1. Electronic control circuit for an auto door locking system, comprising: a control unit (20) with at least one induction coil (3) in order to forward a data query to an external contactless data carrier and to trigger the unlocking of the auto door locking system, if a valid one from the named data carrier Answer is received, a proximity sensor with at least one proximity sensor electrode (5) to trigger the forwarding of the named data query when a person approaches the named proximity sensor electrode, the said proximity sensor electrode (5) and the named induction coil (3) being designed in this way that they can be accommodated in the outer door handle of a car (7), characterized by an electrostatic shield (21) between the named proximity sensor electrode (5) and the named induction coil (3). 2. Control circuit according to claim 1, in which said proximity sensor electrode (5) is covered by insulating material. 3. Control circuit according to one of claims 1 to 2, in which said proximity sensor acts capacitively to sense changes in capacitance on the or said proximity sensor electrodes (5). 4. Control circuit according to one of claims 1 to 3, in which said induction coil (3) is connected in series with a capacitance (4) for impedance matching. 5. Control circuit according to one of claims 1 to 4, in which said induction coil (3) has a longitudinal ferrite core The proximity sensor includes two longitudinal proximity electrodes (5) on each side of the ferrite core, the electrostatic shield includes two metal plates (21) which separate the core from the two proximity electrodes (5). 6. Control circuit according to one of claims 1 to 5, in which said circuits, said proximity electrodes (5) and said induction coil are all mounted on the same circuit board (2). 7. A control circuit according to claim 6, in which said control unit (20), said proximity sensor electrodes (5) and said induction coil (3) are all mounted on the inside of said printed circuit board (2). 8. Control circuit according to claim 7, in which said printed circuit board (2) is flexible. 9. Control circuit according to one of claims 6 to 8, in which said shield (21) is attached to said printed circuit board (2). 10. Control circuit according to claim 7, in which said shield (21) is designed as part of said printed circuit board (2). 1 1. Control circuit according to one of claims 6 to 10, in which said proximity sensor electrode (5) is designed as a cut strip in said printed circuit board. 12. Control circuit according to one of claims 6 to 1 1, in which said printed circuit board (2) is encapsulated in thermoplastic material. 13. Control circuit according to claim 12, which is mounted in a housing and in which said printed circuit board (2) extends over the entire length of the housing (13). 14. Control circuit according to one of claims 1 to 13, which also contains a touch sensor (22) to determine the contact between the hand of the user and the named car door handle. 15. Control circuit according to claim 14, in which said touch sensor comprises two opposing, on each side of said printed circuit board (2), capacitive electrodes (22) arranged so that the thumb resting on the outside of said housing (13) is one Person is sensed. 16. Control circuit according to one of claims 1 to 15, wherein said control unit (20) contains a microcontroller, which makes it possible to determine changes in capacitance on said proximity electrodes (5). 17. Control circuit according to one of claims 12 to 16, in which said housing (13) is bent and in which said proximity electrodes (5) are bent to adapt to the hand of the user. 18. Car door handle comprising: a longitudinal housing (13) the narrow end of which can be movably attached to the outside of the body of a vehicle, a plurality of electrical cables (12) emerging from the said narrow end of the housing, a control circuit (20 ) according to one of claims 1 to 15 in a cavity (72) within said housing. 19. A car door handle according to claim 18, further including a touch sensor (22) located near the other narrow end of said housing (13) to sense contact between a person's hand and said car door handle , 20. A car door handle according to claim 18, in which said cables (12) are attached to said circuit board (2) by autosplice. 21. A car door handle according to claim 20, in which said cables (12) are secured in parallel to said circuit board (2) by autosplice and cross a seal (121) on the side of the first narrow end so that they are firmly in place kept and moisture infiltration into the named housing (13) can be prevented. 22. Car door handle according to one of claims 18 to 21, in which an electronic circuit (20) is attached to the side of said printed circuit board (2) remote from the said narrow end, an induction coil (3) on said printed circuit board (2 ) is attached between said electronic circuit (20) and said narrow end, said electronic circuit with said cables (12) running by means of tracks on said printed circuit board (2), under said induction coil (3), is electrically connected.