Communications: electrical – Continuously variable indicating – With meter reading
Reexamination Certificate
1999-01-15
2002-10-29
Horabik, Michael (Department: 2635)
Communications: electrical
Continuously variable indicating
With meter reading
C340S870030, C455S151200, C455S039000, C341S176000, C341S023000
Reexamination Certificate
active
06472998
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a receiver of a remote control system, in particular for the closing system of a motor vehicle, which is designed to receive signals of an associated transmitter (
1
), and drives one or more actuators when signal levels above its response threshold are present, and to a method for operating a remote control system.
DE-A 33 41 900 discloses a remote control system for locking and unlocking security systems in vehicles. The remote control system comprises a receiver unit, which is accommodated in the vehicle, and a signal transmitter with its own power supply. By activating the signal transmitter, coded signals are transmitted by it in the direction of the receiver unit. The receiver unit receives the signals, compares them with a stored pattern, and activates a security system when the signal patterns correspond. According to DE-A 33 41 900, the signals which are generated by the signal transmitter are transmitted with variable transmission energy. By increasing the transmission energy as the activation time becomes longer, it is possible, on the one hand, to ensure that the security system is activated with the smallest possible amount of transmission energy for the given distance between the vehicle and transmitter, in order to make it more difficult for third parties to intercept the transmission signal. At the same time, it is advantageous to place as little load as possible on the battery. On the other hand, the transmission power which increases as the activation time of the transmitter becomes longer is intended to ensure that the remote control system still functions even under difficult reception conditions, such windows coated with ice, for example.
In modern closing systems with a remote control system, the transmitter is as a rule accommodated in the vehicle key. The receiver usually includes an intelligent electronic system which is capable of driving a plurality of actuators. Such a receiver monitors, controls and adjusts a wide variety of functions such as the central locking of the doors, the anti-theft alarm system, the interior lights, the window lifting devices and the sunroof. In particular in the case of the comfort functions of the closing of the windows and of the sunroof it is indispensable for safety reasons (for example nip guard) that the function should be carried out only for as long as an input signal is applied to the receiver. However, the receiver cannot detect for what reasons there are no longer any signals present. This may be desired by the operator, but it may also occur owing to an excessively low signal level. The latter occurs, for example, if the operator moves too far away from the reception device or if the function is triggered at the limit of the range, and the field strength at the receiver drops below the response threshold as a result of the transmitter moving. This leads to the initiated function (for example closing of the windows) being interrupted or entirely broken off.
SUMMARY OF THE INVENTION
The invention, has an objective to specify a receiver and a method which make it possible to remedy the aforesaid deficiencies.
In the receiver according to the invention, this is achieved by means for changing the response threshold of the receiver.
According to the method in accordance with the invention, the following method steps are provided:
reduction of the response threshold of the receiver after a signal of the transmitter is detected, and
increasing the response threshold of the receiver after a signal fails to occur.
The receiver and/or the method according to the invention ensure that a comfort function, such as the closing of the windows or of the sunroof, is maintained even if the signal level is reduced as a result of the transmitter moving or as a result of the distance between the transmitter and receiver increasing. A jerky or uneven operation as a result of dropping signal levels is largely ruled out, since decreasing signal levels are compensated over a wide range by virtue of a reduced response threshold of the receiver.
The changing of the response threshold of the receiver can be effected in the form of switching over by means of an attenuator or amplification element which can be varied by means of a control signal. In accordance with a further embodiment, in order to change the response threshold, a comparator is provided for comparing the level of the received signal with a setpoint value. The control signal for the attenuator or amplification element, and/or the setpoint value for the comparator, are expediently made available by a microprocessor contained in the receiver. The receiver may be, in particular, a radio receiver or an infrared receiver.
REFERENCES:
patent: 4763121 (1988-08-01), Tomoda et al.
patent: 5420568 (1995-05-01), Iida et al.
patent: 5650774 (1997-07-01), Drori
patent: 5717387 (1998-02-01), Suman et al.
patent: 5723911 (1998-03-01), Glehr
patent: 6091341 (2000-07-01), Nose et al.
patent: 3341900 (1985-05-01), None
patent: 0496024 (1992-07-01), None
Lässle Hans-Peter
Schmid Dietmar
Farber Martin A.
Horabik Michael
Mannesmann VDO AG
Nguyen Nam
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