EP1476622A1

EP1476622A1 - Induction coil, in particular for a vehicle door locking system

Info

Publication number: EP1476622A1
Application number: EP03701427A
Authority: EP
Inventors: Peter Kull; Fabian Beck
Original assignee: Schaffner EMV AG
Current assignee: Schaffner EMV AG
Priority date: 2002-02-22
Filing date: 2003-02-17
Publication date: 2004-11-17
Also published as: AU2003203121A1; WO2003071068A1

Abstract

The invention relates to an electronic control circuit for a motor car-door locking system. Said circuit comprises: a control unit (20) with an induction coil (3) for relaying a data request to an external contactless data carrier and for triggering the unlocking of the motor car-door locking system, if a valid response has been received from the data carrier; a proximity sensor comprising at least one proximity electrode (5) for triggering the relaying of the data request, if a person approaches the proximity sensor. The induction coil (3) comprises a ferrite core (35) and a wire (33) that is wound around said core and is housed in a cavity (72) of a handle (7) of the motor car-door locking system. At least one part (31) of the wire winding is connected mechanically to the surface of the ferrite core, in such a way that the coil can be further processed as an SMD component.

Description

Induction coil, in particular 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 pull handle with such a system. The present invention also relates to a car door pull handle which is provided 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 pull 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 hanger). 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 using 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 request 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, ie 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. If a person approaches the electrode, this capacity is changed, which can trigger a signal to send a data query. Will be one

If the electrode is installed in the immediate vicinity of the electromagnetic transceiver, which generates many stray fields, it is disturbed by the changes in charge in the transceiver, so that incorrect attempts at approach are identified and unwanted power-consuming data queries are triggered. In order to communicate with the external contactless data carrier, known electronic control circuits for car door locking systems often comprise a transceiver with a resonance circuit, which consists, for example, of an induction coil of a capacitance. The induction coil generates an electromagnetic field that is received by the external data carrier. The desired range is typically around one and a half meters.

Conventional induction coils, however, generate a parasitic stray field that can impair the proximity sensors and possibly trigger unwanted power-consuming data queries. In addition, these stray fields reduce the useful power that is available for data transmission with the external data carriers.

In order to achieve the desired transmission frequency of, for example, 129 kHz with a conventional capacitance of approximately 15nF, an inductance of approximately 110 μH is used. However, such a value requires a large coil. The thickness available in the handle is very small; a relatively long induction coil can be attached.

In order to enable stable data transmission with the external data carrier, it is essential that the resonance frequency of the resonance circuit is stable and well defined. To achieve this goal, induction coils with precisely defined inductance values are also required. However, it is difficult to manufacture long flat induction coils with precisely predefined inductance values. In particular, it was found in the context of the invention that the first and last turns of the antenna wire in the vicinity of the two ends of the ferrite core have a significant influence on the inductance value of the induction coil. It is important that these turns run parallel to the edge of the ferrite core and that there is no unreproducible air gap between the wire and the ferrite core. Especially during the assembly of the induction coil (but also later due to vibrations and bumps) the turns of the antenna wire often slide over the smooth ferrite core. Another disadvantage is that assembly is made more difficult because the position of the two free ends of the antenna wire is unknown.

In the case of shorter, thicker induction coils, this problem is usually solved by strongly tensioning the wire on the ferrite core. With a long rectangular induction coil, however, the required voltage would require a wire with a large diameter so that the wire does not tear. A large wire diameter would increase the total thickness of the induction coil, which makes it impossible to integrate it into a flat car door pull handle. According to the invention, the diameter of the wire should be less than 0.3 mm, which limits the maximum wire tension to approximately 100 N. This tension is insufficient to ensure a reproducible and stable position of the windings on a very long ferrite core with a rectangular or square cut.

Attempts have also been made to cast the wound induction coil in a polymeric material that holds the turns in place. This solution also has the disadvantage that the thickness of the induction coil is increased. In addition, the casting involves additional costs.

It is therefore an object of the present invention to produce an induction coil which is flat enough to be able to be accommodated in a cavity in a vehicle handle and which has an inductance value which is as precisely predefined and as stable as possible.

Another object of the present invention is to produce an induction coil which can be accommodated in a cavity in a vehicle handle and which generates as little parasitic electromagnetic stray fields as possible. Another object of the present invention is to produce an induction coil, the cost of which can be kept low and which can be manipulated with as little effort as possible and mounted on a printed circuit board.

These goals and other advantageous properties result from an electronic control circuit according to the claims. In particular, the problems are solved by an electronic control circuit for a car 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 car door locking system, if the named A valid response is received on a data carrier, said inductor comprising a ferrite core and a wire wound around the ferrite core, said inductor in a cavity in one

Handle of the named Autotur locking system is housed, and wherein at least a portion of the turns of said wire is mechanically connected to the surface of said ferrite core.

Through the exact mechanical connection - that is, through the precise fastening of the wire to the surface of the ferrite core, the distance between adjacent turns, the distance between each turn and the ferrite core and the direction of the turns can be controlled and ensured much better.

In a preferred embodiment of the invention, at least one end of the ferrite core is metallized and the end of the named wire is soldered, welded or glued to this metallized end. This enables simple manipulation of the induction coil, which can be mounted on a circuit board like a component. 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 shows the induction coil shown in perspective.

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 projects into the interior 90 of the vehicle door with the end facing away from the handle 7 and is connected to the car door locking system, which is not shown for reasons of clarity. The car 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 locking system in the most convenient way possible. The control circuit 1 is connected to the car 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 comprises a touch sensor 22 which triggers a signal as soon as the user places a finger (in particular a thumb) on the outer side of the handle. A proximity sensor 5 triggers another signal when a hand or another grounded object approaches, particularly 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 emitted by one Control unit 20 interpreted with a microcontroller and at least one induction coil 3 in order to forward a data query to an external contactless data carrier, not shown. 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 capacitance using a charge transfer measuring system, ie by switching the unknown capacitance with a larger reference capacitance via switches.

The data carrier preferably consists of a transponder (which can be integrated, for example, into a chip card or into a key holder) and is "awakened" 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 auto 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 FIG. 2. 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 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. The contactless transceiver comprises a resonance circuit shown in FIG. 3 with an induction coil 3 and a capacitance 4, which are mounted directly on the printed circuit board 2. It is used to match the impedance of the transceiver to the driver stage of the microcontroller.

The induction coil 3 consists of a winding of an electrically insulated wire 33 on a plate-shaped ferromagnetic ferrite core 35. The length of the ferrite core is preferably greater than 40 mm, for example 64 mm, while its thickness is less than 4 mm, for example 2 mm.

In the example shown, the two end parts 31 of the wound wire 33 are mechanically connected to the surface of the ferrite core 35, that is to say fastened, for example by connecting means such as adhesive or an adhesive tape between the wire 33 and the ferrite core 35, or by the surface of the Wire 33 is solidarized directly with the surface of the ferrite core 35, for example by soldering.

Preferably, the end portions 31 of the wound wire 33 are either glued directly to the ferrite core 35 or by one double-sided adhesive tape mechanically connected to the surface of the ferrite core 35. However, adhesive tape has the disadvantage that the thickness of the coil is increased by the tape, which can prove to be a disadvantage for the integration of the coil into a thin handle. This mechanical connection enables the distance between adjacent turns, between each turn and the ferrite core and the angle between each turn and the edge of the ferrite core to be kept stable and reproducible. It would also be possible, instead of only the first and last, to mechanically connect all the turns to the surface of the ferrite core, for example using self-adhesive wire.

In the example shown, the two ends 32 of the ferrite core are also metallized. The metallization is carried out, for example, by immersion in a tin or conductive lacquer casting bath. It would also be possible to metallize the ends of the ferrite core by means of a galvanic process.

The two free ends of the wire are soldered to the named metallized ends. This also enables the angle and the position of the last turns to be checked. In addition, it enables simplified manipulation of the induction coil, which, like a conventional SMD component, can be soldered directly onto the printed circuit board 2, regardless of the position of the wire. The coil can thus be processed as an SMD component.

Instead of soldering the wire to the ends of the ferrite core, it is also possible within the scope of the invention to weld it or to glue it with a conductive adhesive. In this description and in the claims, the term soldering or soldering must therefore also include welding or gluing with an electrically conductive adhesive.

The capacitance 4 is preferably a ceramic or polypropylene capacitance with a capacitance of approximately 3.3nF to 18nF, but preferably of approximately 15 to 18nF. It is preferably soldered directly onto a metallized end 32 of the ferrite core 35. To increase the overall thickness of the To avoid induction coil, a foot 40 of the capacitance 4 is soldered to the narrow lateral side of the ferrite core.

The ferrite core is preferably made of Ni-Zn. In one variant, it consists of Mn-Zn and is covered with an insulating layer. This layer can, for example, be a lacquer layer or consist of adhesive tape.

The control circuit 1 also comprises a proximity sensor with, in this preferred example, two proximity sensor electrodes 5, 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 movement of a hand between the bow-shaped outer part 7 of the handle and the vehicle door can be determined quickly and reliably.

An electrostatic shield 21 is preferably provided between the proximity sensor electrodes 5 and the induction coil 3. This shielding prevents, inter alia, that the determination of the capacitance between the proximity sensor electrodes and the ground is disturbed by the induction coil 3.

A touch sensor 22 is mounted on the left side of the printed circuit board 2 in such a way that contacts between the hand, in particular the thumb, the user requesting access in the vehicle and the outside of the handle can be determined. In the preferred example shown, the touch sensor contains a capacitance, with an electrode on the lower side of the printed circuit board 2 and another electrode on the upper side of the printed circuit board, which can consist, for example, of the basic interconnects on the upper side of the printed circuit board. The capacitance of the touch sensor is preferably less than 5pF. The touch sensor also contains a capacitance measuring system in order to determine the changes in capacitance or charge caused by the user finger and to direct it 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 tracks 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 because 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. 2.

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 can be used which is sprayed at a temperature of approximately 215 ° degrees and low pressure.

Since the material is injection molded 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. It is therefore also possible to reduce the thickness of the spray material above the electrodes 22 and 5 in order not to reduce their sensitivity.

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 a car door locking system, comprising: a control unit (20) with at least one induction coil (3) to forward a data query to an external contactless data carrier and to trigger the unlocking of the car door locking system if a valid answer from said data carrier is received, said induction coil (3) comprising a ferrite core (35) and a wire (33) wound around the ferrite core, said induction coil (3) in a cavity (72) in a handle (7) of said Autotur locking system is housed, characterized in that at least a part (31) of the turns of the said wire is mechanically connected to at least a part of the surface of the ferrite core.

2. Electronic control circuit according to claim 1, in which at least one end of said wire is glued to said ferrite core.

3. Electronic control circuit according to one of claims 1 or 2, in which at least one end (32) of said ferrite core is metallized and in which the ends of said wire are soldered to said metallized end.

4. Electronic control circuit according to one of claims 1 to 3, in which said control unit (20) comprises at least one capacitance (4) connected in series with said induction coil (3) and in which one foot (40) of said capacitance (4 ) is soldered onto the named metallized end (32) of the named ferrite core (35).

5. Electronic control circuit according to claim 3, in which said ferrite core is plate-shaped and in which said foot (40) of said capacitance (4) is soldered on the narrow side of said ferrite core.

6. Electronic control circuit according to one of claims 1 to 5, in which said control unit (20) is mounted on a circuit board (2) and in which said induction coil (3) is mounted as an SMD component on said circuit board (2) ,

7. Electronic control circuit according to one of claims 1 to 6, in which the length of said ferrite core (35) is greater than 40 mm and the thickness of said ferrite core is less than 4 mm.

8. Electronic control circuit according to one of claims 1 to 6, in which said ferrite core consists of Ni-Zn.

9. Electronic control circuit according to one of claims 1 to 6, in which the said ferrite core consists of Mn-Zn and in which at least the said metallized ends (32) are covered with a layer insulating the ferrite.

10. Electronic control circuit according to claim 9, in which said insulating layer is a lacquer layer.

11. Electronic control circuit according to claim 9, in which said insulating layer consists of an insulating adhesive tape.

12. Electronic control circuit according to one of claims 1 to 11, with a proximity sensor with at least one proximity sensor electrode (5) to trigger the forwarding of said data query when a person approaches the said proximity sensor electrode, said proximity sensor electrode (5) so are designed so that they can be accommodated in the outside door handle of a car (7).

13. Electronic control circuit according to claim 12, characterized by an electrostatic shield (21) between said proximity sensor electrode (5) and said induction coil (3).

14. Electronic control circuit according to claim 1, in which said proximity sensor electrode (5) is covered by insulating material.

15. Electronic control circuit according to one of the claims

13 through 14 in which said proximity sensor includes two longitudinal longitudinal electrodes (5) on each side of said ferrite core, said electrostatic shield including two metal plates (21) which separate said core from said two proximity electrodes (5).

16. Electronic 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).

17. An electronic 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).

18. Electronic control circuit according to claim 7, in which said printed circuit board (2) is flexible.

19. Electronic control circuit according to one of claims 1 to 18, which also contains a touch sensor (22) to the contact to determine between the hand of the user and the named car door handle (7).

20. Electronic control circuit according to claim 12, in which said touch sensor comprises two capacitive electrodes (22), which are located opposite one another and are arranged on each side of said printed circuit board (2), so that the thumb resting on the outside of said housing (13) a person is sensed.

21. Electronic control circuit according to one of claims 1 to 20, in which said ferrite core is bent to the

Handle to adjust.

22. car door pull handle comprising: a longitudinal housing (13) whose narrow end 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, an electronic control circuit ( 20) according to one of claims 1 to 21 in a cavity (72) within said housing.

23. A method for producing an induction coil (3) in an electronic control circuit for a car door locking system, comprising the following steps:

Metallization of the ends (32) of the ferrite core, winding a wire (33) around a plate-shaped

Ferrite core (35) with a length greater than 40 mm,

Solder the ends of the named wire to the named metallized ends.

24. The method of claim 23, wherein at least a portion of said wire is mechanically connected to the surface of said ferrite core.