Keyless system for actuating a motor-vehicle door latch

• US 20020125994A1
• Filed: 02/19/2002
• Published: 09/12/2002
• Est. Priority Date: 02/21/2001
• Status: Active Grant

• Current Assignee: Huf Hulsbeck & Furst GmbH & Co. KG
• Original Assignee: Kiekert AG (Lingyun Industrial Corporation Limited)
• Inventors: Gerdes, Bernd, Sandau, Helmut
• Granted Patent: US 7,126,453 B2
• Time in Patent Office: Days
• US Class Current: 340/5.62
• CPC Class Codes: E05B 81/77 comprising sensors detecting the presence of the hand of a user
• CPC Class Codes: E05B 81/78 as part of a hands-free locking or unlocking operation
• CPC Class Codes: G07C 2209/65 using means for sensing the user's hand
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A keyless actuating system has a switchable electrical device, a coded transponder adapted to be carried by a user, and a vehicle-mounted interrogating unit adapted when enabled to remotely coact with the transponder for switching the device when the transponder holds a predetermined code. A first capacitor element is carried on the vehicle, and a second capacitor element is carried on the user. A control circuit determines the capacitance between the first and second elements when the user is near the vehicle for enabling the interrogating unit only when the capacitance between the first and second elements passes a predetermined threshold. Normally the second capacitor element is actually the user.

Claims

1. In a motor vehicle, a system comprising:

a switchable electrical device;

a coded transponder adapted to be carried by a user;

vehicle-mounted interrogating means adapted when enabled to remotely coact with the transponder for switching the device when the transponder holds a predetermined code;

a first capacitor element on the vehicle;

a second capacitor element on the user; and

means for determining the capacitance between the first and second elements when the user is near the vehicle for enabling the interrogating means only when the capacitance between the first and second elements passes a predetermined threshold.

2. The motor-vehicle system defined in claim 1 wherein the means for determining charges the first element so as to create a sensor field of predetermined size and the threshold is set such that only when the second element enters the field is the interrogating means enabled.

3. The motor-vehicle system defined in claim 2 wherein the means for determining sets the threshold so as to establish a response field that is within and substantially smaller than the sensor field.

4. The motor-vehicle system defined in claim 1 wherein the second capacitor element is the user.

5. The motor-vehicle system defined in claim 1 wherein the user has with respect to ground a capacitance of several hundred picofarads and the user forms through ground a closed electrical circuit with the first element.

6. The motor-vehicle system defined in claim 1 wherein the vehicle has a door handle on which the first element is mounted and with respect to which the first element is insulated.

7. The motor-vehicle system defined in claim 8, further comprising

a capacitance shield to one side of the first element.

8. The motor-vehicle system defined in claim 1, further comprising:

a third capacitor element on the vehicle; and

means for determining the capacitance between the second and third elements when the user is near the vehicle for locking the vehicle when the capacitance between the second and third elements passes a predetermine threshold.

9. The motor-vehicle system defined in claim 8 wherein the vehicle has a door handle and the first and third elements are set in the door handle.

10. The motor-vehicle system defined in claim 9 wherein the first and third elements are insulated from each other and from the handle.

11. In a motor vehicle, a keyless latch system comprising:

an electrically openable door latch;

a coded transponder adapted to be carried by a user;

vehicle-mounted interrogating means adapted when enabled to remotely coact with the transponder for unlocking the latch when the transponder holds a predetermined code;

a door handle associated with the latch;

a capacitor element on the handle; and

means for determining the capacitance between the element and the user when the user is near the vehicle for enabling the interrogating means only when the capacitance between the element and the user passes a predetermined threshold.

12. The keyless latch system defined in claim 11, further comprising

an actuator for locking the latch;

a second element on the handle separate from the first-mentioned element;

control means connected to the actuator for determining the capacitance between the second element and the user when the user is near the vehicle for locking the latch when the capacitance between the second element and the user passes a predetermined threshold.

13. The keyless latch system defined in claim 12 wherein the control means is only effective when the latch is not locked.