Nissan Motor Company Limited

Takahisa Tomoda

Mikio Takeuchi

Kinichiro Nakano

Motoki Hirano

Kenichi Mitamura

A radio signal transmitter for use in an automotive keyless entry system, is resistant to damage even when subject bending stresses. The radio code transmitter has a thin housing. A substrate for a transmitter circuit is housed within the thin internal space of the housing. A plurality of circuit components making up the transmitter circuit are mounted on the substrate. The circuit components are arranged in such a manner that relatively large components are near the edges of the substrate and relatively small components are nearer the center of the substrate.

Pocket-portable radio code signal transmitter for automotive keyless

In a ratio-mediated keyless entry system for an automotive vehicle, two vehicle-mounted antennae, lying in mutually perpendicular planes are used to receive radio signals from a portable, manually operable transmitter. When the transmitter is left in the passenger compartment and then the doors are locked, the system generates an alarm to notify the driver of the fact. On antenna completely encircles the passenger compartment. Encircling the passenger compartment with one of the vehicle-mounted antennae ensures that wherever the transmitter is left in the passenger compartment, its presence will be detected no matter how limited the transmitter's range.

Antenna device in automotive keyless entry system

A method for detecting an encoded radio signal involves comparing the received signal amplitude with a predetermined threshold amplitude. The difference between the received signal-component amplitude and the noise-component amplitude is derived and used to adjust the threshold amplitude. By adjustng the threshold amplitude depending upon the difference between the signal-component amplitude and the noise-component amplitude, mis-detection which could occur otherwise when the reception amplitude of the noise component is relatively high or the reception amplitude of the signal component is relatively low can be successfully and satisfactorily avoided. In order to implement the foregoing process, an encoded radio signal detecting system comprises detecting means separately detecting the signal-component amplitude and the noise-component amplitude, arithmetic means for deriving the difference between the received signal-component amplitude and the noise-component amplitude and deriving a value proportional to the derived difference, which derived value serves as a threshold amplitude, and comparator means for comparing the received signal amplitude with the threshold amplitude, thereby detecting the presence or absence of encoded radio signals.

Method and system for detecting encoded radio signals

A keyless entry system allows fully automatic operation of a door lock device of an automotive vehicle. The system recognizes the presence and absence of an authorized user and automatically locks or unlocks the vehicle door lock device according to the presence or absence of the authorized user. The keyless entry system is provided with a controller mounted on a vehicle and designed to periodically generate a radio demand signal and transmit same at regular intervals. A radio code signal transmitter is normally in a stand-by state in which it is ready to transmit a radio code signal indicative of a preset code in response to the radio demand signal. The radio code signal transmitter is of a pocket-portable size for convenient transport by an authorized user. The radio signal transmission between the controller and the radio code signal transmitter is performed within a predetermined distance range around the vehicle. Therefore, the radio code signal transmitter becomes active when the authorized user carrying the same enters into the predetermined radio signal transmission range to transmit the radio code signal to the controller. The controller receives and compares the preset code with a unique code stored in its memory and operates a door lock device for unlocking when the codes match. On the other hand, while the authorized user is output of the radio signal transmission range, the controller detects absence of the radio code signal to operate the door lock device for locking.

Keyless entry system for automatically operating automotive door locking

An antenna for an automotive keyless entry system can ensure radio-wave transmission between a transmitter and a controller and can be conveniently mounted on a vehicle body. The antenna for an automotive keyless entry system, has a first planar antenna loop, and a second antenna loop disposed within the first antenna loop and lying in the plane thereof. The axis of the second antenna loop is substantially perpendicular to the axis of the first antenna loop. The first and second antenna loops form an antenna assembly which can be conveniently mounted on the vehicle body as, for example, within a door mirror of the vehicle.

Growing community of inventors

Sagamihara, Japan

Takahisa Tomoda