TRANSPONDER AND SENSOR APPARATUS
FOR SENSING AND TRANSMITTING
VEHICLE TDRE PARAMETER DATA
CROSS REFERENCE TO CO-PENDING
This application is a continuation-in-part of application Ser. No. 07/254,206, filed Jun. 3, 1994 in the names of Harvey J. Kulka and John H. Schramm, co-pending on the filing date of this application and now U.S. Pat. No. 5,483, 827 issued Jan. 16, 1996.
BACKGROUND OF THE INVENTION
The present invention relates, in general, to vehicle tires and, more specifically, to transponders mounted in or on vehicle tires for transmitting tire identification and/or operating condition data.
DESCRIPTION OF THE ART
Recently there has developed interest in mounting transponders in or on a vehicle tire to provide tire identification data during the manufacture and use of the tire. Further developments have led to the mounting of such transponders in the tire to sense and transmit tire pressure data along with tire identification data, as shown in U.S. Pat. Nos. 4,911,217; 5,181,975 and 5,218,861.
The devices disclosed in these and other related patents utilize a passive integrated circuit transponder which is mounted directly within the tire during the manufacture of the tire or under a patch attached to an exterior side wall of the tire. The transponder responds to an interrogation signal from a unit external to the tire and uses the interrogation signal as a source of electrical energy to transmit digital signals relating to a tire identification code and/or tire pressure data. Due to the mounting of the transponder within the tire in close proximity to the steel belts found in most vehicle tires, a specially constructed antenna is required. Such antennas are in the form of two spaced electrodes or a coil of wire turns. Further, such transponders are required to be mounted in a specific location within the tire in order to receive and transmit signals at adequate signal strength levels without interference.
In addition to a unique tire identification code for a tire which is stored in a memory on the integrated circuit transponder, such devices also incorporate a pressure sensor mounted on the circuit board containing the transponder to provide tire pressure data at the time of receipt of the interrogation signal. Such pressure sensors are in the form of an elastomeric material having a variable conductivity, as well as piezo-resistive transducers, silicone capacitive pressure transducers, or a variable conductant laminant of conductive ink. The transponder includes circuitry for digitizing the pressure data for transmission with or without tire identification data to the external interrogation source.
U.S. Pat. No. 4,695,823 discloses a transponder with an internal or on-board power supply in the form of a long period oscillator connected to a battery. The oscillator actuates a temperature and/or pressure sensor at a set time to obtain the temperature and pressure of the tire. The sensed temperature and pressure are compared with preset temperature and pressure threshold values and, when the threshold values are exceeded, the transponder transmits an encoded signal representative of the out-of-range temperature or pressure signal to a remote location, such as a light display mounted on the vehicle to provide an indication mat at least
one of the temperature and pressure threshold values have been exceeded.
However, such tire mounted transponders, while effectively transmitting tire identification and certain tire pressure
5 or temperature data, are not without limitation. Most of the previously devised tire mounted transponders are passive and receive electrical power from an external interrogation signal source. This limits the effective distance range between the external interrogation signal source and the
10 transponder. Indeed, such external interrogation sources have utilized a hand-held wand which must be placed immediately adjacent to the tire to transmit the interrogation signal to the transponder on the tire and to receive the data signals therefrom.
15 Such tire mounted transponders have also required special antenna configurations and mounting positions on the tire to provide adequate data signal strength. Further, since such transponders are actuated only upon the receipt of an interrogation signal or at a set time through an on-board
20 oscillator, such transponders only transmit instantaneous pressure and temperature data at the time of receipt of the interrogation signal or the activation signal from the on-board oscillator. Such transponders are incapable of actively accumulating pressure and temperature data, such
25 as maximum or minimum tire pressure and temperature, over a set period of use of the tire. Such tire mounted transponders are also incapable of determining the actual usage of the tire in terms of miles of use. The aforementioned maximum and minimum temperature and pressure, as
30 well as the amount of use of a tire, are extremely useful parameters in determining the condition of the tire in order to extend wear, remaining useful life, safe or unsafe tire condition, etc.
3S Thus, it would be desirable to provide a transponder and tire parameter sensor apparatus which can be mounted in a large number of different positions within or on a vehicle tire without the need for a special antenna configuration. It would also be desirable to provide such a tire mounted transponder and sensor apparatus which operates in a semiactive mode to automatically and continuously sense, record and transmit tire operating parameters during the use of the tire on a vehicle. It would also be desirable to provide a tire mounted transponder and sensor apparatus which is capable
45 of storing such tire operating parameters for subsequent transmission to an external control source upon receipt of an interrogation signal from the external control source. It would also be desirable to provide a tire mounted transponder and sensor apparatus which is capable of monitoring
50 various tire operating parameters, including pressure, temperature and number of revolutions of the tire, over a predetermined time period and to detect maximum and minimum values of at least certain of such parameters. It would also be desirable to provide a tire mounted transpon
55 der and sensor apparatus which is operable, without repair or part replacement, for the entire expected life of the tire. Finally, it would be desirable to provide a tire mounted transponder and sensor apparatus which is capable of receiving interrogation signals from an external control source and
^ for transmitting tire operating parameter data to the external control source over longer distances as compared to previously devised tire mounted transponders.
SUMMARY OF THE INVENTION
65 The present invention is a transponder and sensor apparatus for sensing and transmitting vehicle tire condition parameters to a remote location external of a vehicle.