System for automatically charging the battery of a remote transmitter for use in a vehicle security system

• US 6,366,051 B1
• Filed: 08/08/2001
• Issued: 04/02/2002
• Est. Priority Date: 05/08/2000
• Status: Expired due to Term

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Campbell, Douglas C., Nantz, John S., Ghabra, Riad, King, Ronald O., Tang, Qingfeng
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/924,284
• Publication Number:
  US 20020027424A1
• Time in Patent Office: 237 Days
• Field of Search: 320/108, 320/157, 320/158, 320/159, 320/155, 320/162, 320/163, 320/164, 320/5
• US Class Current: 320/108
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034

Abstract

A system for automatically charging a battery of a remote keyless entry transmitter includes a voltage monitoring circuit having a first microprocessor which monitors battery voltage and which causes the transmitter to send an RF signal to a receiver in the form of a base station on a motor vehicle. The signal causes a charging circuit of the base station to activate an inductive field to cause the battery to be fully charged. In one embodiment, the first microprocessor also causes the transmitter to send a second signal to the base station to shut down the charging field when the battery voltage reaches a predetermined upper limit. In another embodiment, a second microprocessor of the base station tracks the charging time and shuts down the charging field when the charging time reaches a predetermined amount. Alternatively, charging can be done by direct contact or other means. In this way, the system not only allows for extended battery life by limiting the number of charge cycles on the battery but also allows for optimum discharge of the battery before a charging cycle begins.

Claims

1. A charging system for automatically charging a battery of a remote transmitter, the charging system comprising:

a voltage monitoring circuit for monitoring voltage of the battery and causing the transmitter to transmit a first signal when the voltage drops below a predetermined lower limit;

a charging circuit for charging the battery during a charging cycle in response to the first signal when the battery is coupled to the charging circuit for charging; and

a determining circuit for determining when the battery is fully charged and providing a corresponding fully charged signal wherein the charging circuit stops charging the battery in response to the fully charged signal.

2. The charging system as claimed in claim 1 wherein the charging circuit is inductively coupled to the battery during charging.

3. The charging system as claimed in claim 1 wherein the voltage monitoring circuit includes a first microprocessor programmed to monitor the voltage of the battery.

4. The charging system as claimed in claim 1 wherein the determining circuit includes a charging time monitoring circuit for monitoring the amount of time the battery is coupled to the charging circuit and is being charged thereby and providing the fully charged signal when the time reaches a predetermined amount.

5. The charging system as claimed in claim 4 wherein the charging time monitoring circuit includes a second microprocessor programmed to monitor the amount of time that the charging circuit charges the battery to ensure that the battery is fully charged before the charging cycle is complete.

6. The charging system as claimed in claim 1 wherein the first signal is an RF signal.

7. The charging system as claimed in claim 3 wherein the first microprocessor is further programmed to cause the transmitter to transmit the fully charged signal when the battery is fully charged.

8. The charging system as claimed in claim 7 wherein the fully charged signal is an RF signal.