WO1998000319A1

WO1998000319A1 - Improved remote keyless entry device

Info

Publication number: WO1998000319A1
Application number: PCT/US1997/010407
Authority: WO
Inventors: Randy L. Yach
Original assignee: Microchip Technology Incorporated
Priority date: 1996-06-19
Filing date: 1997-06-18
Publication date: 1998-01-08

Abstract

A remote keyless entry transmitter device (10) for a motor vehicle includes an ignition key operatively associated with the ignition key for selectively transmitting a coded signal to lock or unlock a door of the vehicle to gain access to the vehicle's ignition system. The transmitter (17) and a rechargeable energy source (20) are provided within the ignition key. A charging circuit (19) located in the key serves to electrically connect the rechargeable energy source to a power source of the vehicle, such as the battery, to charge the energy source when the ignition key is in the ignition system. The rechargeable energy source (20) may be a battery, or a capacitor.

Description

IMPROVED REMOTE KEYLESS ENTRY DEVICE

Background of the Invention

The present invention relates generally to systems and methods for gaining access to enclosures through locked accessways by means of remote keyless entry devices, and more particularly to improved systems and methods for maintaining such devices in a state of full preparedness for use.

The advent of remote keyless entry for such purposes as gaining entry to automobiles and other battery operated motor vehicles has led to a profusion of devices, each generally comprising a transmitter which may be activated by the user

- typically by depressing a button - to transmit a code sequence at some distance from the vehicle by telemetry to a receiver at or in operative relationship with a lock for the door to the vehicle, to lock or unlock the door. The remote keyless entry systems provide a considerable convenience to the user. For example, the transmitter may be activated while the user is holding packages, without need for fumbling for keys through a pocket or purse. Where the user has reason, for concern about safety, to gain fast entry to a vehicle in a remote location of a parking lot at night, the remote keyless entry (RKE) transmitter saves considerable time over the traditional key- type locking/unlocking system. Generally, the RKE transmitter has been incorporated into a unit which forms a part of a key-chain or key-ring that holds the ignition key for the vehicle. The automobile industry has, however, been struggling with ways in which to reduce the size of the transmitter. More recently, the RKE transmitter has been incorporated into the ignition key itself, as part of the key head. Wherever it may be physically integrated into a unit, the RKE transmitter has posed a problem of maintaining an adequate power supply for long lifetime under conditions of relatively frequent use. Power is supplied from one or two small batteries in the transmitter which, for adequacy of supply, impact not only on considerations of suitable lifetime of the device before battery replacement is necessitated, but on the physical size of the RKE unit. Where the RKE transmitter is integrated into the key- head, the size of the key becomes a factor.

The RKE transmitter battery life, of course, depends on the power consumption of the device. Battery life is reduced as the standby current of the transmitter increases. One technique for solving the problem of large standby current, and consequent fairly rapid depletion of battery energy, is to use components in the transmitter which have only relatively low standby current requirements. This method has practical limitations.

It is a principal aim of the present invention to provide improved devices and methods for RKE transmitters, and especially for maintaining such transmitters in a state of preparedness for use at all times despite the amount of usage to which they may be subjected.

Summary of the Invention In a presently preferred embodiment of the invention, a new and improved technique for maintaining adequate power of the RKE transmitter over extended periods of time, despite frequent usage of the transmitter, employs a rechargeable battery to supply power to the transmitter. The invention takes advantage of the fact that the key is retained in the ignition system of a vehicle throughout operation of the vehicle. If the RKE transmitter is incorporated within the ignition key itself, such as in the key head, a recharging path may be provided through the ignition system of the vehicle, or at least through the keyslot of the ignition system, to the rechargeable battery in the RKE transmitter, such that the battery is recharged — and the transmitter is thereby maintained at or near full power -- whenever the key is in the ignition.

The circuit may be such that the recharging takes place so long as the key is in the ignition, whether or not the engine (or true motor in the case of an electrically powered vehicle) is operating. Or, the charge path for the RKE transmitter battery may be activated only when the ignition is on, i.e., when the key is in the accessory position, or the car is started or is in actual operation. In an alternative embodiment of the invention, a capacitor is used in place of a rechargeable battery. This is particularly advantageous where the vehicle is subject to frequent usage around the clock, such as with many types of municipal vehicles that are shared by workers on different shifts, such as police cars, firehouse cars, ambulances, and other emergency vehicles.

Therefore, a more specific object of the invention is to provide an energy rechargeable RKE transmitter for motor vehicles, where the recharging of a power source is accommodated by a charging circuit that includes the vehicle ignition system.

Brief Description of the Drawings

The above and still further aims, objects, features, aspects, and attendant advantages of the invention will become apparent from a consideration of the best mode presently contemplated for practicing the invention, as implemented in a preferred embodiment and method, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a partly structural and partly schematic diagram of an embodiment of an ignition key and circuit for recharging the keyless remote entry transmitter, using an energy storage element which may be a rechargeable battery or a capacitor, according to the present invention; and

FIG. 2 is a depiction of a keyslot with charging contacts for cooperation with charging contacts on the key to enable recharging of the energy storage element of the transmitter.

Detailed Description of the Preferred embodiment and Method

FIG. 1 is a diagram of a remote keyless entry transmitter 10 comprising an ignition key 12 and electrical circuitry 15 incorporated within the key. The key itself is mechanically of conventional type in that it is intended for use in the ignition system of a motor vehicle or other motorized device or equipment by inserting the shank 16 of the key into the ignition keyslot (or simply, the "ignition") of the vehicle, and turning the keyhead 19 to rotate the keyslot assembly (FIG. 2) to a position in which the vehicle's starter is actuated. This in turn cranks the fuel- powered engine of the vehicle (or in the case of an "electric car", connects the batteries to an electric motor), to "start" the vehicle. The shank is encoded, typically by means of a set of peculiarly shaped indentations 25 on one or both longitudinal edges thereof, although other means may be used, to cooperate with a matching code of mating indentations in the ignition (relatively unique to the particular vehicle) that will allow the key to be rotated in the ignition to start the vehicle and keep it running. Customarily, an intermediate position of rotation of the ignition key is provided to allow accessories such as the car radio to be powered on and operated without starting or running the vehicle.

Usually, but not always, the ignition key is also used to lock and unlock the driver's door. If not, an additional key is provided for that purpose. In recent years, it has become customary for manufacturers and dealers to offer the option of remote keyless entry to the vehicle by providing a transmitter that actuates the door locks of the vehicle by a coded radio frequency (RF), or telemetry, signal. Using the transmitter, the vehicle operator may unlock or lock the car doors at a distance from the vehicle (hence, the name "remote keyless entry") that depends on the strength of the signal and the location of the lock-actuating receiver in the vehicle. Although the transmitter means is operatively associated with the ignition key in that it is physically located within the key in the embodiment of FIG. 1, the operative association may instead be location of the transmitter means in a separate element that is mechanically and electrically connectable to the key. In the preferred embodiment, the transmitter means includes a radio frequency (RF) transmitter 17, and a control integrated circuit (IC) 18 such as a microcontroller electrically coupled to transmitter 17, located in the keyhead 19. A rechargeable energy source 20, in the form of an energy storage device such as a battery or a capacitor, is electrically coupled to the transmitter means for electrical activation thereof when an actuator such as a depressible button 22 is operated by the key holder (i.e. , the person holding the key). If energy storage device 20 is a rechargeable battery, it is preferably retained in a compartment that may be opened in the keyhead, for periodic replacement of the battery according to the manufacturer's specifications.

According to the invention, charging circuit means are provided within ignition key 10 for electrically connecting the rechargeable energy source 20 to a power source of the vehicle, such as to the vehicle's battery and/or the electrical charging circuit from the engine, for recharging the energy source while the ignition key is in the ignition system. To that end, electrical circuitry 15 in the ignition key 10 includes physical electrical contacts 27, 28, which may be on opposite sides of the key, for electrically engaging similarly positioned electrical contacts 30, 31 at the keyslot 35 (FIG. 2) of the vehicle's ignition system. The contacts are not shown to scale, nor necessarily in the most appropriate position for the electrical engagement. Preferably, the contacts 27, 28 are located on the shank 16 and, in any event, are electrically insulated from the metal of the key. Preferably, also, the portion of the charging circuit in the vehicle 40, schematically represented by a dashed box in FIG. 2, provides only a trickle charge from the power source 42 of the vehicle, either the battery or the charging circuit from the motor.

In use, key 10 is used to open the compartment which provides access to the ignition system — in this case, by unlocking the doors to the car's interior, either by means of the remote keyless transmitter or, if the energy source for the transmitter is depleted, by physically unlocking the door with the key. When the key 10 is inserted into the car's ignition, and turned in the ignition to start the vehicle, the electrical contacts 27, 28 on the key electrically engage the contacts 30, 31 associated with the keyslot or the ignition, so that the energy source 20 — either a rechargeable battery or a capacitor — is recharged while the vehicle is being operated.

Alternatively, the charging circuit may be arranged and adapted such that the energy source is recharged as well while the key is in the accessory position, or even at any time that the key is in the ignition. Since the charge is a trickle charge it is insufficient to deplete the car battery even in a weakened state, or to adversely affect the charging circuit for the car battery if charging of the energy source is accomplished from operation of the engine. As previously indicated herein, the energy source may be a suitably sized capacitor, although a rechargeable battery is preferred. In a method of energizing a remote keyless entry transmitter according to the invention, where the transmitter is associated with a key for operating an ignition system of a motorized equipment, to maintain the transmitter in a state of preparedness for transmitting a coded signal when activated to remotely lock or unlock a compartment of the motorized equipment in which the ignition system is accessible, from locations within a predetermined distance from a receiver on the motorized equipment, the following steps are employed. A rechargeable energy source is incorporated within the key for activating the transmitter, and a portion of a charging circuit for the energy source is provided within the key. A cooperating portion of the charging circuit is further provided within the motorized equipment to enable the energy source to be recharged when the key is in the ignition system.

Also, the transmitter may be incorporated within the key, together with means such as the depressible button for connecting the energy source to the transmitter for activation thereof. The cooperating portion of the charging circuit is provided in the motorized equipment to recharge the energy source from either the battery or the motor of the motorized equipment.

Although a presently contemplated best mode of practicing the invention has been described herein, it will be understood by those skilled in the art to which the invention pertains, from a consideration of the foregoing description, that variations and modifications of the preferred embodiment and method of the invention may be made without departing from the true spirit and scope of the invention. For example, the invention is not restricted to automobiles or land-based vehicles, but may be used with power boats, aircraft, and indeed, with any normally locked or lockable apparatus or equipment that is not necessarily vehicular in and of itself but requires the use of an ignition key for operating a motor or engines thereof, such as certain types of cranes or other construction or earth moving equipment. Accordingly, it is intended that the invention shall be limited only to the extent required by the appended claims and the rules and principles of the applicable case law.

Claims

What is claimed is:

1. A remote keyless entry transmitter, comprising: an ignition key; transmitter means operatively associated with said ignition key for selectively transmitting a coded signal to lock or unlock a compartment of a motorized device containing an ignition system for a motor of said device which is operable by means of said ignition key; a rechargeable energy source within said ignition key; and charging circuit means in said key for electrically connecting said rechargeable energy source to a power source of the device for charging the energy source when the ignition key is in the ignition system.

2. The remote keyless entry transmitter of claim 1 , wherein the rechargeable energy source is a battery.

3. The remote keyless entry transmitter of claim 1 , wherein the rechargeable energy source is a capacitor.

4. The remote keyless entry transmitter of claim 1, wherein the charging circuit means is adapted to connect said energy source to a battery of the motorized device.

5. The remote keyless entry transmitter of claim 1 , wherein the charging circuit means is adapted to electrically connect said energy source to the motor of said device.

6. The remote keyless entry transmitter of claim 1, wherein the transmitter means is incorporated within the ignition key.

7. A method of energizing a remote keyless entry transmitter associated with a key for operating an ignition system of a motorized equipment, to maintain the transmitter in a state of preparedness for transmitting a coded signal when activated to remotely lock or unlock a compartment of the motorized equipment in which the ignition system is accessible, from locations within a predetermined distance from a receiver on the motorized equipment, comprising the steps of: incorporating a rechargeable energy source within the key for activating the transmitter; providing a portion of a charging circuit for the energy source within the key; and further providing a cooperating portion of the charging circuit within the motorized equipment to enable the energy source to be recharged when the key is in the ignition system.

8. The method of claim 7, further including incorporating the transmitter within the key, together with means for connecting the energy source to the transmitter for activation thereof.

9. The method of claim 8, wherein the connecting means includes a depressible button.

10. The method of claim 7, wherein the step of providing a cooperating portion of the charging circuit to enable the energy source to be recharged includes connecting said cooperating portion for recharging the energy source from at least one of a battery or a motor of the motorized equipment.

11. In combination with an ignition key for a motor vehicle, the key having a keyhead and a shank extending therefrom for insertion in a keyslot of an ignition system of the vehicle to enable the vehicle's motor to be started, the key further having an actuatable transmitter operatively associated therewith for remote locking and unlocking of the vehicle by telemetry when actuated within a predetermined distance from the vehicle, an improvement comprising a rechargeable power source for actuating said transmitter incorporated in said key, and electrical circuit contact means exposed on said key and positioned for cooperation with charging contacts in said keyslot for charging said power source when said shank is inserted in the slot.

12. The improvement of claim 11, wherein the rechargeable power source is a battery.

13. The improvement of claim 11, wherein the rechargeable power source is a capacitor.

14. The improvement of claim 11, wherein the electrical circuit contact means on said key are positioned for electrical contact with the charging contacts in said keyslot for energizing the rechargeable power source when the shank is fully inserted in the keyslot.

15. The improvement of claim 11, wherein the electrical circuit contact means on said key are positioned for electrical contact with the charging contacts in said keyslot for energizing the rechargeable power source when the shank is fully inserted in the keyslot and the key is turned to a position for operation of the vehicle.

16. The improvement of claim 11, wherein the transmitter is incorporated within the key.

17. The improvement of claim 16, further including a depressible button exposed in the keyhead for electrically connecting the power source to the transmitter for actuation thereof when depressed.