Patent Publication Number: US-2004041698-A1

Title: Code learning device for tire pressure monitor

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001] This application claims the priority benefit of Taiwan application serial no. 091119986, filed Aug. 30, 2002, the full disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention generally relates to a code learning device for a tire pressure monitor, and more particularly relates to a code learning device for a tire pressure monitor monitoring the conditions of tires, which is provided with a simplified code learning process.  
       [0004] 2. Description of the Related Art  
       [0005] Many related technologies and devices for monitoring the pressure of the tires have been known in the conventional arts. For example, U.S. patent application Ser. No. 09/910,725 entitled “Method for Monitoring Tire Pressure of Pneumatic Tire and Device Therefor” filed on Jul. 24, 2001 and commonly assigned to the assignee of the present application, discloses a device which comprises sensor modules installed in each of the pneumatic tires for sensing the conditions of the tires, and then encoding and transmitting the conditions of the tires by radio frequency signals. The device also has a decoder module for receiving the radio frequency signals transmitted by the sensor module and thus determining the present conditions of the pneumatic tires.  
       [0006] However, in the above mentioned patent application, while the decoder module identifies the relationship between the code of the sensor module and the positions of the pneumatic tires, the operator has to deflate the tires of the vehicle. By rapid changing of the tire pressure, the sensor modules installed in the tires continuously transmit signals and then the decoder recognizes the code in the signals, thereby identifying the relationship between the positions of the tires and the sensor modules installed therein. Then, the deflated tires of the vehicle have to be inflated before the driver use the vehicle again. Obviously, such process is relatively time consuming, inconvenient, and complicated.  
       [0007] Besides, U.S. Pat. No. 6,369,703 issued to Lill on Apr. 9, 2002 entitled “Tire pressure monitor and location identification system”, discloses a tire pressure monitoring and identification system in a vehicle includes a tire pressure monitor operatively connected to each tire, a plurality of transponders, and a central system receiver. Each of the transponders has a unique identification code and is fixed to the vehicle adjacent to a predetermined tire. During operation, each tire pressure monitor transmits tire pressure data to its corresponding transponder. The transponder adds its unique location identification code to the tire pressure data and transmits the data to the central system receiver. The central system receiver selectively displays the tire pressure data by tire location. However, the tire pressure monitoring of this patent is complex and easily influenced by the environmental electromagnetic waves.  
       [0008] Therefore, the foregoing conventional code learning methods are unable to provide a fast and effective code learning mode. There exists a need for a code learning device and method of tire pressure monitor to simplifying the code learning process of the tire pressure monitor.  
       SUMMARY OF THE INVENTION  
       [0009] It is an object of the present invention to provide a tire monitoring device for monitoring conditions of tires, and the tire monitoring device is able to easily identify the positions of the tire pressure sensors installed in the respective tires.  
       [0010] It is another object of the present invention to provide a code learning method of tire monitoring device for identifying the positions of the tire pressure sensor installed in the respective tires without complex operations.  
       [0011] In order to achieve the objects mentioned hereinabove, the present invention provides a code learning device for a tire pressure monitor attached to a vehicle. The code learning device comprises a sensor module installed in a tire of the vehicle for sensing the condition of the tire and transmitting the condition by a radio frequency (RF) signal. The sensor module further comprises a transponder for generating the electric power in response to an electromagnetic wave, thereby transmitting the identifying code of the sensor module. The code learning device further comprises a reader for transmitting the electromagnetic wave of the first frequency and receiving the identifying code transmitted from the transponder, and a tire monitoring module installed in the vehicle for receiving the condition transmitted from the sensor module.  
       [0012] According to another aspect of the present invention, the present invention further provides a code learning method for a tire monitoring device attached to a vehicle comprising the following steps of: providing a plurality of sensor modules installed in the respective tires of the vehicle for sensing the conditions of the tires and transmitting the signals including the conditions, and having an identifying code; providing a plurality of transponders respectively attached to the sensor modules for be induced by an electromagnetic wave at a first frequency so as to transmit the identifying code of the sensor module; and transmitting the electromagnetic wave of the first frequency in the vicinity of one of the tires for inducing the transponder installed in the one of the tires and transmitting the identifying code of the sensor module installed in the one of the tires.  
       [0013] Accordingly, since the tire monitor according to the present invention is provided with the transponder, the user easily identifies the identifying code of the sensor module installed in the tires. Further, the power supply is not required for the transponder, so the lifetime of the sensor module is not reduced due to the operating of the transponder. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.  
     [0015]FIG. 1 is a system block diagram of a tire monitoring device comprising a code learning device according to the present invention.  
     [0016]FIG. 2 is a schematic circuit diagram of the transponder shown in FIG. 1 which includes an integrated circuit (IC) and a parallel inductor-capacitor oscillation circuit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0017] Now referring to FIG. 1, it shows a block diagram of a tire monitoring device  1  with code learning function according to the present invention. The tire monitoring device  1  installed in a vehicle comprises a plurality of sensor modules  10   a ,  10   b ,  10   c ,  10   d , and a tire monitoring module  30 . The tire monitoring module  30  includes a microprocessor  32 , a receiver  34  with an antenna  35 , and a display unit  36 .  
     [0018] The sensor modules  10   a ,  10   b ,  10   c , and  10   d  are respectively installed in the front right (FR) tire, the front left (FL) tire, the rear right (RR) tire, and the rear left (RL) tire of a vehicle. The sensor modules  30   a - d  comprise sensor application-specific integrated circuits (ASIC)  14   a ,  14   b ,  14   c ,  14   d  for sensing the condition of the tires in the vehicle and an antennas  13   a ,  13   b ,  13   c ,  13   d  for transmitting the condition. Specifically, the ASICs  14   a - d  are used for sensing the conditions of the tires, such as pressure and temperature of the tires, and then encoding and transmitting the conditions of the tires by radio frequency signals via the antennas  13   a - d . Each of the ASICs  14   a - d  further comprise an identifying code which is transmitted with the radio frequency signals. Such sensor module can be seen in the U.S. patent application Ser. No. 09/910,725 entitled “Method for Monitoring Tire Pressure of Pneumatic Tire and Device Therefor” filed on Jul. 24, 2001, which is commonly assigned to the assignee of the present application and incorporated herein by reference.  
     [0019] The tire monitoring device  1  according to the present invention further a hand held reader  20 , and the sensor modules  10   a ,  10   b ,  10   c ,  10   d  respectively comprise transponders  12   a ,  12   b ,  12   c ,  12   d . The hand held reader  20  includes a microprocessor  22 , transmitting buttons  24   a ,  24   b ,  24   c ,  24   d , a transceiver  26  with an antenna  27 , and a memory  28 . It will be apparent to those skilled in the art that the transponders  12   a - d  can be induced by a radio wave or an electromagnetic wave at a specific frequency for generating power and powering an integrated circuit (IC), thereby transmitting the identifying code of the ASICs  14   a - d . Also, since the hand held reader  20  is provided with the transmitting buttons  24   a - d , the hand held reader  20  can transmit the radio wave at the specific frequency when the transmitting buttons  24   a - d  is pressed.  
     [0020] Before the tire monitoring device  1  according the present invention is used for monitoring the condition of the tires, the tire monitoring device  1  firstly needs to carry out a code learning process for identifying the identifying codes of the sensor modules installed in the respective tires of the vehicle. In the code learning process, for example, the user holds the hand held reader  20 , approaches the front right (FR), and presses the transmitting button  24   a  for transmitting the radio wave at the specific frequency. The transponder  12   a  is induced by the radio wave of the specific frequency for generating electric power and powering the IC which transmits the identifying code of the ASIC  14   a  via another radio frequency signal. The transceiver  26  of the hand held reader  20  may receive the radio frequency signal and store the identifying code of the ASIC  14   a  installed in the front right tire into the memory  28 . The user then approaches the other tires and presses the respective transmitting button  24   b ,  24   c ,  24   d  so that all of the identifying codes of the ASICs installed in the tires is identified. Then, the hand held reader  20  transmits the identifying codes of the respective tires to the memory  31  in the tire monitoring module  30  by means of radio waves or a transmitting line, whereby the tire monitoring module  30  receives the signals of the tire conditions from the sensor modules  10   a - d  installed in the respective tires and identifies the tire from which the signals is transmitted. Further, the tire monitoring module  30  can transmit the conditions of the tires to the hand held reader  20  by radio waves or a transmitting line for providing the function of remote monitoring.  
     [0021] Furthermore, according to the embodiment of the present invention, while the user manipulates the hand held reader  20  for actuating the transponder, the intensity or amplitude of the radio wave at the specific frequency transmitted from the hand held reader  20  is limited such that the intensity of the radio wave is not enough to actuate the transponder until the hand held reader  20  approaches the transponder (i.e. the tire) below the distance which is from about 7 to about 20 cm, thereby avoiding the influence of the other tires.  
     [0022] More specifically, as shown in FIG. 2, the transponder  12  is provided with an integrated circuit (IC)  40  and a parallel inductor-capacitor oscillation circuit  50  which is electrically connected to the VCC (Power) pin  42  and the GND (Ground) pin  44  of the IC  40 . The oscillation frequency of the oscillation circuit  50  is the specific frequency. Accordingly, when the hand held reader  20  approaches the oscillation circuit  50  and transmits the radio wave at the specific frequency, the oscillation circuit  50  is induced by the radio wave for generating the voltage and powering the integrated circuit  40  to transmit another radio frequency signal which comprises the identifying code of the ASIC and is received by the hand held reader  20 .  
     [0023] In a specific case, the specific frequency of the transponders  12   a - d  is about 125 KHz and the frequency of the radio frequency signal transmitted from the transponders  12   a - d  is about 422.92 MHz or about 315 MHz.  
     [0024] Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.