Information transmission and reception system for a vehicle
This application is a continuation of application Ser. No. 06/896,337, filed Aug. 13, 1986 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an information transmission and reception system for a vehicle which supplies information from any vehicular information source, such as switches, sensors and so on, to a vehicle information receiver which makes use of that information from the information source such as warning indicators, and normal loads such as headlights, etc. 
     2. Description of the Prior Art 
     In conventional transmission and reception systems applied to vehicles, electrical connections between vehicle information sources, such as switches and sensors, and vehicle information handling parts, such as loads and indicators, have always been in a one-to-one relationship with wire harness. 
     FIG. 1 shows a conventional transmission and reception system applied to the vehicle as described above. 
     As shown in FIG. 1, the vehicle is divided into an engine compartment denoted by &lt;ENG.&gt;, a dashboard central section denoted by &lt;DASH&gt;, an instrument panel denoted by &lt;INST&gt;, and a trunk denoted by &lt;TRUNK&gt;. 
     The engine compartment &lt;ENG.&gt; has a power supply (battery) 1, a right-hand front lamp group 3, a left-hand front lamp group 5, an automatic transmission (hereinafter, referred to as A/T) position detection switch group 7, and an A/T shift switch group 9. 
     The above-mentioned front lamp groups 3, 5 each include a head lamp main a, a head lamp dimmer b, a clearance lamp c, a front turn signal (side marker lamp) d, and a side turn signal e. 
     The above-mentioned A/T position detection switch group 7 includes five detection switches each for detecting a shift position from among first (1-range), second (2-range), drive (D-range), neutral (N-range), reversal (R-range), and parking (P-range). 
     The above-mentioned A/T shift switch group 9 comprises three shift change switches covering 1 range - 2 range (1-2), 2 range - 3 range (2-3), 3 range - 4 range (3-4) and an oil temperature monitor switch (oil). 
     The dashboard section &lt;DASH&gt; includes a circuit breaker 11, a front lamp switch group 13, and a peripheral switch group 15. 
     The front lamp switch group 13 is provided with five operation switches denoted by the same symbols a, b, c, d, and e used for the lamp groups 3 and 5. That is to say, symbol a in the group 13 denotes a switch for the lamp main, symbol b in the group 13 denotes a switch for the dimmer, symbol c in the group 13 denotes a switch for the clearance lamp, symbol d in the group 13 denotes a switch for the front turn signal lamp, and symbol e in the group 13 denotes a switch for the side turn signal lamp. 
     The peripheral switch group 15 includes all switches and sensors not included in the engine or in the trunk, specifically, a parking brake switch Pa, an exhaust gas temperature sensor E, and a door switch Do. 
     The instrument panel &lt;INST&gt; includes an A/T position indicator 17, a warning lamp group 19, and a rear actuator switch group 21. 
     The above-mentioned A/T position indicator 17 is provided with six indicators displaying the shift gear positions 1, 2, D, N, R, and P corresponding to the above-described A/T position detection switch group 7. 
     The above-mentioned warning lamps 19 include a parking brake warning lamp Pa, an exhaust temperature warning lamp E, and a warning lamp Do indicating that a door is incompletely closed. 
     The above-described rear part actuator switch group 21 comprises a trunk lid opener solenoid switch T, fuel lid opener solenoid switch F, rear defogger resistor switch R, and power antenna motor switch A. 
     The trunk actuator group 23 comprises a trunk lid opener solenoid 23T, a fuel lid opener solenoid 23F, a rear defogger resistor 23R, and a power antenna motor 23A. In addition, an A/T (automatic transmission) control unit 25 is disposed in the trunk. A wire harness 27 extending the length of the vehicle interconnects these lamps, indicators, actuators, and so on. 
     It should be noted that various additional electrical appliances will be installed in the vehicle and serve either as information supply elements or information receiving elements. In the example given above of connections between conventional vehicle information supply elements and information receiving elements, the wire harness 27 is used to connect the various switches, sensors, etc with the corresponding indicators and actuators, as well as to the power supply 1 and short-circuit protector (circuit breaker) 11. 
     There is a problem in that the transmission and reception system which uses the wire harness as shown in FIG. 1 requires a relatively large harness under the recent circumstances in which the number of automotive electrical appliances is constantly increasing. As the diameter of each wire harness increases, the branching between harnesses becomes more complex so that overall manufacture and wiring also becomes more complex. 
     There is another problem in that since in the transmission and reception system using a wire harness as shown in FIG. 1, the signal transmission lines and high-voltage supply lines inevitably interfere, which reduces the reliability of signal transmission and reception despite noise-free countermeasures. 
     On the other hand, a multiplex transmission reception systems which solve the problems of the transmission and reception system described above have been proposed, for example, in Japanese Patent Application Unexamined Open No. Sho 50-27932 and Japanese Patent Application Unexamined Open No. Sho 57-208746. 
     FIG. 2 shows the basic structure of the multiplex transmission and reception system mentioned above applied to the vehicle. 
     In the conventional multiplex transmission and reception system shown in FIG. 2, the vehicle is divided into four regions, i.e., engine compartment, dashboard central section, instrument panel, and trunk, each position being provided with a dedicated multiplex transmission and reception unit 29, 31, 33, and 35 connected via a bus network 37 as shown in FIG. 2. 
     The network 37 may be of a loop type (refer to the Japanese Patent Application Unexamined Open No. 57-208746) in place of a bus type, or alternatively of a star type. In addition, normal vehicular wiring may be used for the trunk line 37 or alternatively a shielded cable or optical fiber may be used. 
     Each multiplex transmission and reception unit shown in FIG. 2 comprises a unit capable of transmitting and receiving related signals. Further a processing of signal transmission and reception is carried out in each multiplex transmission and reception system. 
     For example, suppose that lamp main switch a in the front lamp switch group 13 is turned on so that the turn-on signal is outputted to the transmission and reception unit 31 for the dashboard &lt;DASH&gt; via the line λ 1 . Then, the multiplex transmission and reception unit 31 reads the signal-level state on the line λ 1  and sends same to a predetermined address corresponding to lamp main switch 13a, and sends a signal ordering both lamp mains a in the left and right main lamp groups 3, 5 to be turned on at a predetermined timing to another multiplex transmission and reception unit 29. The addressing and data transmission timing are carried out on the basis of an address clock signal in the form of an M-series time series code. As appreciated from FIG. 2, the transmission and reception units communicate between the addressed transmission memory and the addressed reception memory via a single line 37 and therefore the overall processing is complex. 
     The conventional multiplex transmission and reception system described above with reference to FIG. 2 has the following problems: 
     (1) Each multiplex transmission and reception unit must transmit and receive the data to and from each of the other positions and must carry out communications with all of the other multiplex transmission and reception units. Therefore, a high-level protocol and correspondingly complex structure are necessary. 
     (2) Each multiplex transmission and reception unit employs a high-level protocol. Therefore, if one of the multiplex transmission and reception units should fail, the symptoms of failure would appear at every unit, whereby failure diagnosis and trouble shooting would be difficult. 
     (3) The whole system must be connected by way of a high-level protocol. Therefore, as each multiplex transmission and reception unit is highly integrated, modification and alternation thereof are rather difficult, and thus the system lacks general-purpose utility. 
     (4) Each multiplex transmission and reception unit must be relatively large if a single standardized unit is to be mass-produced to provide general-purpose utility, in order to satisfy the needs of the largest station in the information transmission and reception system. Therefore, the cost of the whole system is increased. 
     SUMMARY OF THE INVENTION 
     With these various problems in mind, it is an object of the present invention to provide a transmission and reception system for a vehicle with a simple structure and with no need for a high-level protocol, which is easy to operate, and which is flexible and of general-purposed utility. 
     The above-described object can be achieved by providing: an information transmission and reception system, comprising: (a) a plurality of information elements, some of which generating information for use by the remainder thereof, grouped into information sources and information receivers, the number of the information elements in the information sources and in the information receivers being limited to no more than a given number, (b) a plurality of information transmission units, each connected electrically to corresponding one of the information sources, (c) a plurality of information reception units, each connected electrically to corresponding one of the information receivers, and (d) means for connecting electrically each of the information transmission units to at least a corresponding one of the information reception units. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present invention may be obtained from the following detailed description taken in conjunction with the attached drawings in which: 
     FIG. 1 is a simplified wiring diagram of a conventional transmission and reception system for a vehicle using a wire harness; 
     FIG. 2 is a simplified block diagram of another conventional multiplex-type transmission and reception system for a vehicle; 
     FIG. 3 is a simplified block diagram of a first preferred embodiment of a transmission and reception system for a vehicle according to the present invention; 
     FIG. 4 is a simplified block diagram of the circuitry of each transmission unit and reception unit of the transmission and reception system in the first preferred embodiment shown in FIG. 3; 
     FIG. 5 is a simplified block diagram of a second preferred embodiment of the transmission and reception system according, to the present invention; 
     FIG. 6 is a simplified block diagram of the circuitry of each transmission and reception unit in the second preferred embodiment shown in FIG. 5; 
     FIG. 7 is a simplified block diagram of an address clock generator shown in FIG. 6; 
     FIG. 8a-8c are signal waveform charts for the address clock generator shown in FIG. 7; 
     FIGS. 9 and 10 are diagrams of system configurations of other preferred embodiments according to the present invention; 
     FIG. 11 is a diagram of the system configuration of a model of the transmission and reception system in the first preferred embodiment shown in FIGS. 3 and 4; 
     FIG. 12 is a diagram of the system configuration of a model of the transmission and reception system in the second preferred embodiment shown in FIGS. 5 through 8; and 
     FIG. 13 is a diagram of the system configuration of a model of the conventional multiplex transmission and reception system shown in FIG. 2. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will hereinafter be made to the drawings in order to facilitate understanding of the present invention. 
     (General Description) 
     The elements shown in FIGS. 1 and 2 can be thought of as an information field made up of information sources and information receivers grouped locally into the information field units &lt;ENG.&gt;, &lt;DASH&gt;, &lt;INST&gt; and &lt;TRUNK&gt;. The terms &#34;information source&#34; and &#34;information receiver&#34; refer to the coordinated collections of elements that are labelled with numerals in FIGS. 1 and 2 (with the exception of the front lamp groups 3 and 5, which make up a single information receiver). 
     The information units have a known limited number of unidirectional connections for information flow. In the case illustrated in FIGS. 1 and 2, five such unidirectional connections are necessary, as reflected in the five groups G1-G5 shown in Table 1. 
     
                                           TABLE 1                                 
__________________________________________________________________________
(GROUP DIVISION OF TRANSMISSION/RECEPTION UNITS)                          
ENG.                   DASH        INST              TRUNK                
TRANS./RECEP. UNIT                                                        
UNIT                                                                      
GROUP                                                                     
     RG1  TG3    TG5   TG1   TG2   RG2    RG3  TG4   RG4   RG5            
__________________________________________________________________________
G1   FRONT             FRONT                                              
     LAMP              LAMP                                               
     GROUP             SWITCH                                             
     (3,5)             GROUP                                              
                       (13)                                               
 ##STR1##                                                                 
G2                           DASH  WARNING                                
                             PERIPH-                                      
                                   LAMP                                   
                             ERY   GROUP                                  
                             SWITCH                                       
                                   (19)                                   
                             GROUP                                        
                             (15)                                         
                              ##STR2##                                    
G3        A/T                             A/T                             
          POSITION                        POSI-                           
          DETEC-                          TION                            
          TION                            INDI-                           
          SWITCH                          CATOR                           
          GROUP (7)                       (17)                            
           ##STR3##                                                       
G4                                             REAR  TRUNK                
                                               ACTU- ACTU-                
                                               ATOR  ATOR                 
                                               SWITCH                     
                                                     GROUP                
                                               GROUP (23)                 
                                               (21)                       
                                                ##STR4##                  
G5               A/T                                       A/T            
                 SHIFT                                     CON-           
                 SWITCH                                    TROL           
                 GROUP                                     UNIT           
                 (9)                                       (25)           
                  ##STR5##                                                
__________________________________________________________________________
 
    
     (First Preferred Embodiment) 
     FIG. 3 shows a system configuration of the first preferred embodiment of a multiplex time-division data transmission system for a vehicle according to the present invention. 
     The group 1 (G1) comprises a transmission side in the dashboard unit &lt;DASH&gt; and a reception side in the engine compartment &lt;ENG.&gt;. The transmission side is provided with a transmission unit TG1. The reception side is provided with a reception unit RG1. 
     The group 2 (G2) comprises a transmission side in the dashboard unit &lt;DASH&gt; and a reception side on the instrument panel &lt;INST&gt;. The transmission side is provided with a transmission unit TG2 and reception side with a reception unit RG2. 
     The group 3 (G3) comprises a transmission side in the engine compartment &lt;ENG.&gt; and a reception side on the instrument panel &lt;INST&gt;. The transmission side is provided with a transmission unit TG3 and the reception side is provided with a reception unit RG3. 
     The group 4 (G4) comprises a transmission side on the instrument panel and a reception side in the trunk &lt;TRUNK&gt;. The transmission side is provided with a transmission unit TG4 and reception side with a reception unit RG4. 
     The group 5 (G5) comprises a transmission side in the engine compartment &lt;ENG.&gt; and a reception side in the trunk &lt;TRUNK&gt;. The transmission side is provided with a transmission unit TG5 and reception side with a reception unit RG5. 
     A multiplex time-division data transmission system 37 is made up of five communication circuits, each having a serial signal transmission line L1, L2, L3, L4, and L5 connected between single, corresponding transmission and reception units. 
     FIG. 4 shows the internal circuitry of the transmission and reception units of the first group G1 shown in FIG. 3, which is representative of all of the five communication circuits. 
     The communication circuit 38 of the first group 1 comprises the transmission unit TG1, the reception unit RG1, and a serial signal transmission line L1 connecting these units TG1 and RG1. 
     The transmission and reception units TG1 and RG1 receive power from a vehicle battery 39 via a fuse 41 and power supply lines 43. The transmission unit TG1 is connected to the switches of the front lamp switch group 13 via cables 45. On the other hand, the reception unit RG1 is connected to the right front lamp group 3 and to the left front group 5 via cables 47. It should be noted that in FIG. 4 only one cable 45, only the main switch 13a of the front lamp switch group 13 and only the main lamps 3a, 5a of the right and left front lamp groups 3 and 5 are shown to simplify the drawing. 
     The transmission unit TG1 includes a number of input protection circuits 49 and a transmission circuit 51. The transmission circuit 51 includes an input data buffer 53, an output shift register 55, an encoder 57, and a transmission controller 59. 
     The input protection circuits 49 are connected between each cable 45 and a corresponding, dedicated bit cell of the input data buffer 53 and retransmits the on-and-off signal of the corresponding switch as a binary signal at either a low level (ground potential) or high level (power supply voltage) to the above-described data buffer 53. 
     The input buffer 53 may comprise an 8-bit register which temporarily stores the present signal states of the switches 13a, 13b . . . . 
     The output shift register 55 inputs the contents of the input data buffer 53 in parallel at intervals of 50 milliseconds, shifts the input data &#34;leftward&#34; in FIG. 4 at intervals of one millisecond, and then outputs each bit to the encoder 57 sequentially starting at its leftmost bit position. 
     The encoder 57 modulates the data signal received from the output shift register 55 and outputs a modulated signal on the serial signal transmission line L1. 
     The reception unit RG1 comprises a number of relays 61, each illuminating one of the lamps in each lamp of the lamp groups 3, 5 with the power supply voltage supplied via a corresponding one of the power supply cables 47, an equal number of relay drivers 63, each of which drives one relay 61 and a reception circuit 65. The reception circuit 65 comprises a decoder 67, an input shift register 69, an output data buffer 71, and a reception controller 73. 
     The decoder 67 demodulates a data signal inputted via the above-described serial signal transmission line L1 and outputs the demodulated data signal to the input shift register 69. 
     The input shift register 69 receives the demodulated data from the decoder 67 one bit at a time, each bit causing a &#34;leftward&#34; shift. 
     The output data buffer 71 stores the data in the input shift register in parallel form. 
     The reception controller 73 is activated by the signal received by the above-described decoder 67, controls the timing of the shift operation of the input shift register 69, and outputs a timing signal for the fetched data to the input shift register 69 when it is outputted to the output data buffer 71. 
     The above-described output data buffer 71 holds the signal states at all times and is updated every 50 milliseconds, for example. 
     Given the circuitry shown in FIG. 4, if, e.g., the front lamp main switch 13a is turned on, the corresponding bit cell of the output data buffer 71 will receive that information via transmission circuit 51 and serial signal transmission line L1 so that the corresponding relay 61 will be actuated to illuminate both right and left front main lamps 3a, 5a. 
     It should be noted that although the number of bits of the input data buffer 53 and output shift register 55 are the same, that number may be 16 or 32 as well as 8. Similarly, the number of bits in the input shift register 69 and in the output data buffer 71 of the reception unit RG1 will match. 
     As described above, the multiplex time-division communication system 37 shown in FIG. 3 allows efficient data communication since the communication circuitry for each group operates independently. 
     (Second Preferred Embodiment) 
     FIG. 5 shows the system configuration of the multiplex time-division data transmission system in a second preferred embodiment according to the present invention. 
     The second preferred embodiment differs from the first embodiment in that a common line L (comprising a common data line Lo and address clock line AC) is installed in place of the independent serial signal transmission lines L1 through L5 and an address clock generator 75 is connected to the above-described address clock line, and that an address coincidence circuit 77, 79 is installed in each of the transmission and reception units TG11 through TG15 and RG11 through RG15. 
     As shown in FIG. 5, the transmission and reception units are all connected to the single common data line Lo. Although this connection is apparently similar to the conventional system shown in FIG. 1, the transmission and reception units connected to the data bus Lo perform only information transmission and reception, respectively, according to Table 1. In addition, in contrast to the system shown in FIG. 2, no addresses need be assigned to the separate elements of each information source and information receiver 
     As shown in FIGS. 6, 7 and 8, the address clock generator 75 generates, e.g., a third-order M-series code signal and outputs this address clock signal on the address clock signal line AC. 
     The address coincidence circuits 77, 79 installed in each of the transmission and reception units TG11, RG11, . . . output an address coincidence signal when a three-bit address allocated to the corresponding unit and a three-bit numerical value read from the above-described address clock line AC (address clock signal) coincide. 
     If the same address is assigned to interconnected transmission and reception units TG11, TG12, . . . , TG15 and RG11, RG12, . . . , RG15 within each group, the transmission and reception circuits 51, 65 within each group will be activated together and without activating unrelated circuits. 
     Although five addresses are needed since the transmission and reception units are paired into five groups in the embodiment shown in FIG. 5, a third-order M-series address clock signal which can produce seven distinct addresses will be used to cover the addresses of the transmission and reception units. Third-order M-series address clock signals are discussed in U.S. patent application Ser. No. 780,935 filed on Sept. 6, 1985. The contents of the above-identified U.S. patent application are hereby incorporated by reference. In detail, a generator which generates the third-order M series address clock signal comprises, as shown in FIG. 7, a reference clock generator 215 which generates a reference clock signal C, as shown in (a) of FIG. 8, with a period tc, a three-bit shift register 211 whose clock terminal receives the reference clock signal c, an Exclusive OR gate 213, the output of which is connected to an input terminal of the first bit cell of the shift register 211 and the input terminals of which are connected to the outputs of the second and third bit cells of the shift register 211, and a pulse-width modulator 217 which receives the pulse-width modulated M-series code signal from the third bit cell of the shift register 211 and the reference clock signal c and produces an M-series code synchronous signal CM shown in (c) of FIG. 8, i.e., the third-order address clock signal described above. Each output waveform of the address clock signal generator 75 is shown in (a), (b), and (c) of FIG. 8. 
     In the transmission and reception system 37A in the second preferred embodiment, the common data line Lo is occupied on a time-share basis controlled by the address coincidence signals so that the information from any information source can efficiently be transmitted to the corresponding information receiver, just as in the first preferred embodiment. 
     (Other Preferred Embodiments) 
     FIGS. 9 and 10 show system configurations in which groups consist of either multiple reception units (information reception part) or multiple transmission units (information source). 
     In the above-described first and second preferred embodiments, the information sources and information reception parts enjoy a one-to-one relationship. However, this relationship will not always be the case, as indicated by the front lamp groups 3, 5. As shown in FIGS. 9 and 10, there may be a single transmission unit TGn connected to four reception units, for example. Alternatively, a single reception unit RGn may be connected to four transmission units TGn. 
     In the embodiments shown in FIGS. 9 and 10, the registers in all transmission and reception units would have, e.g., eight-bit contents. 
     As a specific example of the system of FIG. 9, a single switch may be used to illuminate four lamps located at different places 
     As a specific example of the system of FIG. 10, a single alarm lamp may be illuminated by the ANDed sum of alarm signals from four different places. 
     FIG. 11 is a diagram of the configuration of the transmission and reception system in the first preferred embodiment. FIG. 12 is a diagram of the configuration of the transmission and reception system in the second preferred embodiment. FIG. 13 is a diagram of the configuration of the conventional transmission and reception system shown in FIG. 2. It should be noted that the arrows in FIGS. 11-13 denote the direction of flow of information. In addition, A1, A2, A3, . . . A10 denote addresses allocated to respective transmission and reception units and A1, A2, . . . , Ai, . . . , Aj, . . . , Ak, . . . , Al denote addresses allocated to the individual elements of the information sources and information receivers. 
     Comparison of these figures reveals that the inventive systems have a simpler and more flexible lay-out obviating the need for high-level protocols and all but the simplest addressing schemes. 
     It will clearly be understood by those skilled in the art that the foregoing description is made in terms of the preferred embodiments and various changes and modifications are made without departing from the scope of the present invention which is to be defined by the appended claims.