MOBILE DEVICE FOR VEHICLE

• US 20100201483A1
• Filed: 01/15/2010
• Published: 08/12/2010
• Est. Priority Date: 02/06/2009
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Sato, Masaki, Takahashi, Jun, Nakajima, Satoshi, Hayasaka, Satoshi
• Granted Patent: US 8,232,863 B2
• Time in Patent Office: Days
• US Class Current: 340/5.610
• CPC Class Codes: B60R 25/245 where the antenna reception area plays a role
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/64 using a proximity sensor
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence

Abstract

A mobile device for a vehicle includes a receiving unit that receives transmission signals transmitted from individual transmitting antennas of a vehicle-side device; a control unit that determines distances to the individual transmitting antennas using the signal strengths of the received transmission signals; and a transmitting unit that transmits, to the vehicle-side device using wireless communication, data items indicating the distances. In a time period in which communication is not performed between the mobile device and the vehicle-side device, the signal strength of a received signal is measured, thereby obtaining a measurement value, and the measurement value is stored as a noise element in a memory. When communication between the mobile device and the vehicle-side device is performed, correction for noise is performed on the signal strengths of the transmission signals transmitted from the transmitting antennas, and the distances are determined.

Claims

1. A mobile device for a vehicle, the mobile device comprising:

a receiving unit configured to receive transmission signals, each of the transmission signals being transmitted from a corresponding one of a plurality of transmitting antennas of a vehicle-side device;

a control unit configured to determine a distance to each of the plurality of transmitting antennas using a signal strength of a corresponding one of the transmission signals received by the receiving unit; and

a transmitting unit configured to transmit, to the vehicle-side device, data items indicating the distances to the plurality of transmitting antennas determined by the control unit,

wherein, in a time period in which communication is not performed between the mobile device and the vehicle-side device, the control unit measures a signal strength of a signal received by the receiving unit to obtain a measurement value and stores the measurement value as a noise element, and, when communication is performed between the mobile device and the vehicle-side device, the control unit performs correction for noise on the signal strengths of the transmission signals, each of the transmission signals being transmitted from a corresponding one of the plurality of transmitting antennas, and determines the distances to the plurality of transmitting antennas.

2. The mobile device for a vehicle according to claim 1, wherein the control unit performs the correction by subtracting the noise element from the signal strengths of the transmission signals, each of the transmission signals being transmitted from a corresponding one of the plurality of transmitting antennas.

3. The mobile device for a vehicle according to claim 1, wherein the control unit compares a distance Lsn calculated using the signal strength of each of the transmission signals including the noise element with a distance Ln calculated using only the noise element, and, when a ratio of the distance Ln to the distance Lsn is larger than a predetermined value, the control unit transmits, as the distance to a corresponding one of the plurality of transmitting antennas, an alternative data item with which malfunction in the vehicle-side device is prevented.

4. The mobile device for a vehicle according to claim 3, wherein the control unit transmits a data item indicating a maximum distance as the alternative data item with which malfunction in the vehicle-side device is prevented.