Keyless system for actuating a motor-vehicle door latch

• US 7,126,453 B2
• Filed: 02/19/2002
• Issued: 10/24/2006
• Est. Priority Date: 02/21/2001
• Status: Expired due to Fees

• Current Assignee: Huf Hulsbeck & Furst GmbH & Co. KG
• Original Assignee: Kiekert AG (Lingyun Industrial Corporation Limited)
• Inventors: Sandau, Helmut, Gerdes, Bernd
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Brown, Vernal
• Application Number:
  US10/079,141
• Publication Number:
  US 20020125994A1
• Time in Patent Office: 1,708 Days
• Field of Search: 340/5.61, 340/5.62, 340/5.72, 340/5.7, 340/5.1, 340/5.6, 340/5.2, 340/825.69, 340/825.72, 340/10.1, 340/5.64, 340/5.65, 340/426.36, 307/10.1, 307/10.2
• US Class Current: 340/5.61
• 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 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 first capacitor element on the handle;

a control for determining the capacitance between the first capacitor 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, said control defining for said first capacitor element a capacitive sensor field within a detection range of said element and a response range within said detection range and bounded by said threshold so that interrogation commences only with a capacitance change in said response range, said control determining said capacitance change by charge/discharge cycling of the condenser formed between the element and the user;

an actuator for locking the latch;

a second capacitor element on the handle separate from the first capacitor element; and

control means which is only effective when the latch is not locked 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.