Patent Publication Number: US-6658392-B2

Title: Automatic toll collection system for automotive vehicle

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates generally to an automatic toll collection system designed to automatically collect tolls through radio communication between an electronic toll paying unit installed in a vehicle and a toll collecting unit installed in a toll booth on a roadway, and more particularly to a radio-based electronic toll collection system having a security monitor for monitoring abnormalities of an electronic toll paying unit and a toll collecting unit. 
     2. Background of Related Art 
     Japanese Patent First Publication No. 49-98300 teaches an automatic toll collection system designed to collect tolls from each vehicle moving along a toll road automatically through radio communication between an in-vehicle unit and a communication facility installed on the road. If such a system malfunctions, a large amount of time is required to troubleshoot the system, thus resulting in traffic congestion around a toll booth. 
     SUMMARY OF THE INVENTION 
     It is therefore a principal object of the present invention to avoid the disadvantages of the prior art. 
     It is another object of the present invention to provide an improved automatic toll collection system capable of troubleshooting an electronic toll paying unit installed in a vehicle and/or a toll collecting unit installed in a toll booth. 
     According to one aspect of the present invention, there is provided a system for automatic collection of tolls from a vehicle moving along a roadway which comprises: (a) a toll collecting facility installed on the roadway, the toll collecting facility collecting the tolls from an in-vehicle unit installed in the vehicle through radio communication with the in-vehicle unit; and (b) an inspecting facility inspecting the in-vehicle unit when an abnormal condition in which it is impossible to collect the tolls from the in-vehicle unit correctly is encountered, the inspecting facility being located outside the roadway. 
     In the preferred mode of the invention, the toll collecting facility determines whether the abnormal condition is encountered or not through radio communication with the in-vehicle unit. 
     A guidance unit is further provided which provides a guidance signal to the in-vehicle unit for leading the vehicle to the inspecting facility when the abnormal condition is encountered. 
     An image pickup sensor and a gate are further provided which are installed on an automatic toll collection lane mounted on the roadway. When a driver of the vehicle takes action to open the gate, the image pickup sensor picks up an image of the vehicle and the driver. 
     The inspecting facility includes a testing unit which locate an abnormality of the in-vehicle unit through radio communication therebetween. 
     The inspecting facility compares a result of inspection of the in-vehicle unit with determination of whether the abnormal condition is encountered or not made by the toll collecting facility to determine whether the abnormal condition is caused by the in-vehicle unit or the toll collecting facility. 
     A means is further provided which determines whether the abnormal condition is encountered or not prior to communication between the in-vehicle unit and the toll collecting facility. When it is determined that the abnormal condition is encountered, the means leads the vehicle to the inspecting facility. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be understood more fully from the detailed description given hereinbelow and from the accompanying drawings of the preferred embodiment of the invention, which, however, should not be taken to limit the invention to the specific embodiment but are for explanation and understanding only. 
     In the drawings: 
     FIG. 1 is a perspective view which shows an exit of a toll road in which an automatic toll collection system according to the first embodiment of the invention is installed; 
     FIG. 2 is a block diagram which shows a control device installed on an electronic toll collection lane; 
     FIG. 3 is a block diagram which shows an in-vehicle unit; 
     FIG. 4 is a flowchart of a program performed by the in-vehicle unit of FIG. 3; 
     FIG. 5 is an illustration which shows status data indicating abnormalities of the in-vehicle unit of FIG. 3; 
     FIG. 6 is a flowchart of a program performed by a toll collecting unit of the control device of FIG. 2; 
     FIG. 7 is a flowchart of a program performed by a lane control computer of the control device of FIG. 2; 
     FIG. 8 is a block diagram which shows a control device of a test station; 
     FIGS. 9 and 10 show a flowchart of a program performed by a testing unit of a test station; 
     FIG. 11 shows a flowchart of a program performed by a test station computer; 
     FIG. 12 is an illustration which shows a vehicle type identifying device installed in a test station; 
     FIG. 13 is a perspective view which shows an in-vehicle unit adjusting device; 
     FIG. 14 is an illustration which shows a modified form of the in-vehicle adjusting device of FIG. 13; and 
     FIG. 15 is a perspective view which shows an exit of a toll road in which an automatic toll collection system according to the second embodiment of the invention is installed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, particularly to FIG. 1, there is shown an automatic toll collection system according to the first embodiment of the invention which is designed to collect tolls from a vehicle passing through a toll booth. 
     In the drawing, two ETC (Electronic Toll Collection) lanes  1  and a MTC (Manual Toll Collection) lane  2  extend through a toll booth. In each of the ETC lanes  1 , tolls are automatically collected from each vehicle moving along it through radio communication between an electronic toll paying unit installed in the vehicle (referred to as an in-vehicle unit below) and a toll collecting unit installed on the ETC lane  1 . In the MTC lane  2 , tolls are collected manually from each vehicle which has entered it. 
     On each of the ETC lanes  1 , a vehicle type identifying device  3 , a license plate monitor camera  4 , a communication entrance side vehicle detector  5 , an antenna  6 , a communication exit side vehicle detector  7 , a display  8 , a gate entrance side vehicle detector  9 , a gate  10 , a gate opening device  11  having a toll payment error card distributor or a gate opening manual switch, a gate exit side vehicle detector  12 , and a monitor camera  13  are arranged. The toll payment error card distributor produces an error card when the in-vehicle unit is malfunctioning, that is, when tolls has not been collected correctly. When the driver takes the error card, the gate  10  is opened. 
     The vehicle type identifying device  3  identifies the type of a vehicle passing thereby. The license plate monitor camera  4  captures an image of a license plate of the vehicle to read a license plate number out of the image. The vehicle detectors  5  and  7  detect the vehicle to determine the timing for establishing communication with the vehicle. The vehicle detectors  9  and  12  detect the vehicle to determine the timing for opening and closing the gate  10 . 
     A test station  20 , as will be described later in detail, is provided at an exit of the toll booth for checking the in-vehicle unit which has been determined as being in an abnormal condition or which has not completed communication with the toll collecting unit on either of the ETC lanes  1 . Through the test station  20 , a test lane extends from the exit of the toll booth outside the roadway. 
     If the abnormal condition in which it is impossible to collect tolls from the in-vehicle unit correctly is encountered in either of the ETC lanes  1 , then the display  8  indicates “Go to Test Station”. The driver brings the vehicle to the test station  20  and has a check for the status of the in-vehicle unit through a testing unit  21 . The testing unit  21  informs a toll house  22  of test results. For example, when a vehicle having no in-vehicle unit has entered either of the ETC lanes  1  in error, the toll house  22  collects tolls manually. Alternatively, when the in-vehicle unit is malfunctioning, it is repaired or replaced. After having paid the tolls manually or electronically, the vehicle returns to the roadway through a gate  23 . 
     The automatic toll collection system includes a control device  55 , as shown in FIG. 2, one for each ETC lane  1 . The control device  55  has a lane control computer  30  which controls operations of the vehicle type identifying device  3 , the license plate monitor camera  4 , the monitor camera  13 , the vehicle detectors  5 ,  7 ,  9 , and  12 , the gate  10 , and the toll collecting unit  31  (including the antenna  6  in FIG. 1) to identify the vehicles passing through the ETC lane  1  and to indicate through the display  8  the amount of tolls collected by the toll collecting unit  31 . The control device  55  receives information signals from the vehicle detectors  9  and  12  each indicating the passing of the vehicle to open and close the gate  10  and is responsive to an ON signal from the gate opening device  11  to open the gate  10 . 
     The lane control computer  30  communicates with a toll booth computer  100 . The toll booth computer  100  communicates with a network  101  for transmission of information among itself, a test station computer, as will be described later in detail, and a centerized control computer (not shown). 
     FIG. 3 shows the in-vehicle unit installed in each vehicle passing through either of the ETC lanes  1 . 
     The in-vehicle unit  40  includes an antenna  41 , a transceiver  42 , a liquid-crystal display (LDC)  43 , a buzzer  44 , and a control circuit  45 . The transceiver  42  establishes radio communication between the in-vehicle unit  40  and the toll collecting unit through the antenna  41 . The LCD  43  indicates balance information of the IC card  49  and error information of the in-vehicle unit  40 . The control circuit  45  controls the buzzer  44 , the LCD  43 , and the transceiver  42  to perform given functions in an automatic toll payment mode. 
     The control circuit  45  also includes a microprocessor  45   a , a mask ROM  45   b , and an EEPROM  45   c . The mask ROM  45   b  stores therein programs for automatic toll payment. The microprocessor  45   a  performs the programs stored in the mask ROM  45   b . The EEPROM  45   c  stores therein ID data on the in-vehicle unit  40  and status data, as will be described later in detail. 
     The in-vehicle unit  40  also includes a battery  47 , a power supply circuit  48 , and a security sensor  46 . The battery  47  connects with the power supply circuit  48 . The power supply circuit  48  supplies the power to the components of the in-vehicle unit  40 . 
     The above described components of the in-vehicle unit  40  are installed in a casing. Upon insertion of the IC card  49  into the casing, the control circuit  45  reads and writes toll payment data out of and in the IC card  49 . 
     The security sensor  46  detects opening of the casing of the in-vehicle unit  40  by an unauthorized person and outputs a sensor signal to the control circuit  45  which indicates the possibility of the data in the in-vehicle unit  40  has been altered. The security sensor  46  may have the structure, as taught in Japanese Patent First Publication No. 6-12589, wherein wire is attached to an inner surface of a casing of an in-vehicle unit to detect disassembling of the unit when the wire is cut or the structure wherein a photosensor is used to detect incidence of light when the casing is opened. 
     FIG. 4 shows a program or sequence of logical steps performed by the control circuit  45  of the in-vehicle unit  40 . 
     When the in-vehicle unit  40  enters a communication area of the toll collecting unit  31 , the control unit  45  is switched from a sleep mode to an operation mode to initiate the program. 
     First, in step  201 , a diagnostic check is made to inspect functions of the in-vehicle unit  40 . The routine proceeds to step  202  wherein it is determined whether the functions of the in-vehicle unit  40  indicate abnormalities or not. If a YES answer is obtained, then the routine proceeds to step  203  wherein a corresponding error code(s) of status data is rewritten, as listed in FIG.  5 . 
     After either of steps  202  and  203 , the routine proceeds to step  204  wherein it is determined whether a toll payment request signal has been outputted from the toll collecting unit  31  or not. If a YES answer is obtained, then the routine proceeds to step  205  wherein required tolls are paid electronically. The routine proceeds to step  206  wherein it is determined whether the payment of tolls has been completed or not. If a YES answer is obtained, then the routine proceeds to step  207  wherein a payment completion signal is outputted to the toll collecting unit  31 , and a communication result is recorded. 
     If a NO answer is obtained in step  206  meaning that the payment of toll has not been completed, then the routine proceeds to step  208  wherein the communication with the toll collecting unit  31  is disrupted and a fact thereof is recorded in the in-vehicle unit  40 . 
     If a NO answer is obtained in step  204  meaning that commands other than the toll payment have been inputted into the in-vehicle unit  40 , then the routine proceeds to step  209  wherein corresponding operations are performed. The routine proceeds to step  207  wherein results of the operations are recorded. 
     After step  207  or  208 , the in-vehicle unit  40  enters the sleep mode of operation. 
     FIG. 6 shows a program or sequence of logical steps performed by the toll collecting unit  31 . 
     After entering the program, the routine proceeds to step  301  wherein it is determined whether there is an answer signal from the in-vehicle unit  40  or not. This determination is made in cycles until a YES answer is obtained. If a YES answer is obtained, then the routine proceeds to step  302  wherein the status data is read out of the in-vehicle unit  40  and checked to determine whether the in-vehicle unit  40  is in the normal condition or not. If a YES answer is obtained, then the routine proceeds to step  303  wherein the toll payment request signal is outputted to the in-vehicle unit  40 . The routine proceeds to step  304  wherein it is determined whether the payment completion signal, as provided in step  207  of FIG. 4, has been outputted from the in-vehicle unit  40  or not. If a YES answer is obtained, then the routine proceeds to step  305  wherein a command is issued for the in-vehicle unit  40  to display the fact that the payment completion signal has been received by the toll collecting unit  31 . The routine proceeds to step  306  wherein the operation in step  305  is recorded. 
     If a NO answer is obtained in step  304 , then the routine proceeds to step  307  wherein a retry operation is performed to output the toll payment request signal again to the in-vehicle unit  40 . If the payment completion signal is still not outputted from the in-vehicle unit  40  after the toll payment request signal is outputted a given number of times, then the routine proceeds to step  306  wherein the communication with the in-vehicle unit  40  is disrupted, and the fact thereof and an ID number of the in-vehicle unit  40  are recorded. The toll collecting unit  31  issues a command for the in-vehicle unit  40  to record which of the toll collecting units  31  the communication has been disrupted and which of operational steps had been completed when the communication was disrupted. 
     If a NO answer is obtained in step  302  meaning that the status data indicates the abnormalities of the in-vehicle unit  40 , then the routine proceeds to step  308  wherein it is determined whether it is possible to collect the tolls from the in-vehicle unit  40  or not. If the abnormalities of the in-vehicle unit  40  as indicated by the status data allows the tolls to be paid correctly, for example, if the balance of the IC card  49  is smaller than a set amount of money, but it covers the amount of tolls to be paid or the capacity of the battery  47  is lowered, then the routine proceeds to step  309  wherein the toll payment request signal is outputted to the in-vehicle unit  40 . 
     The routine proceeds to step  310  wherein it is determined whether the payment completion signal has been outputted from the in-vehicle unit  40  or not. If a YES answer is obtained, then the routine proceeds to step  311  wherein a command is issued for the in-vehicle unit  40  to display the fact that the payment completion signal has been received by the toll collecting unit  31  and contents of the abnormalities of the in-vehicle unit  40  as indicated by the status data. The routine proceeds to step  306  wherein the operation in step  305  is recorded. 
     If a NO answer is obtained in step  310 , then the routine proceeds to step  312  wherein a retry operation is performed to output the toll payment request signal again to the in-vehicle unit  40 . If the payment completion signal is still not outputted from the in-vehicle unit  40  after the toll payment request signal is outputted a given number of times, then the routine proceeds to step  306  wherein the communication with the in-vehicle unit  40  is disrupted, and the fact thereof is recorded. 
     If a NO answer is obtained in step  308  meaning that the status data indicates the impossibility to collect the tolls from the in-vehicle unit  40 , for example, if the balance of the IC card  49  is insufficient to cover the amount of tolls to be paid, the IC card  49  is not inserted into the in-vehicle unit  40 , an improper IC card is inserted into the in-vehicle unit  40 , or the in-vehicle unit  40  has been opened by an unauthorized person, then the routine proceeds to step  313  wherein a command is issued for the in-vehicle unit  40  to display the contents of the abnormalities of the in-vehicle unit  40  as indicated by the status data and instructions to go to the test station  20 , and the lane control computer  30  of the toll collecting unit  40  is informed of the abnormalities of the in-vehicle unit  40 , and the errors are displayed in the display  8 . 
     The above operation of the toll collecting unit  31  classifies conditions of the in-vehicle unit  40  into five types as listed below. 
     (1) The payment of tolls is completed, and the in-vehicle unit  40  is in the normal condition 
     (2) The payment of tolls is completed, and the in-vehicle unit  40  is in the abnormal condition 
     (3) The in-vehicle unit  40  is in the abnormal condition, and it is impossible to collect tolls from the in-vehicle unit  40   
     (4) The in-vehicle unit  40  is in the normal condition, but it is impossible to collect tolls from the in-vehicle unit  40   
     (5) The in-vehicle unit  40  is in the abnormal condition, but it is possible to collect tolls from the in-vehicle unit  40   
     FIG. 7 shows an operation or program performed by the lane control computer  30  of the control device  55 . 
     The lane control computer  30 , as can be seen in FIG. 2, controls the toll collecting unit  31 , the vehicle type identifying device  3 , the display  8 , the cameras  4  and  13 , and the gate  10 . 
     Upon initiation of the program, the routine proceeds to step  401  to close the gate  10 . The routine proceeds to step  402  wherein an output from the vehicle type identifying device  3  is monitored to determine whether a vehicle has entered the ETC lane  1  or not. If a YES answer is obtained, then the routine proceeds to step  403  wherein it is determined whether the toll collecting unit  31  has communicated with the in-vehicle unit  40  or not. If a YES answer is obtained, then the routine proceeds to step  404  wherein it is determined whether the payment of tolls has been completed or not by monitoring the communication between the in-vehicle unit  40  and the toll collecting unit  31 . If a YES answer is obtained, then the routine proceeds to step  405  wherein the amount of tolls collected from the in-vehicle unit  40  is indicated through the display  8 . The routine proceeds to step  406  to open the gate  10 . The routine proceeds to step  407  wherein it is determined whether the vehicle has passed through the vehicle detector  12  or not. If a YES answer is obtained, then the routine returns back to the initial step. 
     If the toll collecting unit  31  fails to communicate with the vehicle, for example, because the vehicle does not have the in-vehicle unit  40  or if the collection of tolls is not completed and the toll collecting unit  31  indicates the abnormalities of the in-vehicle unit  40 , a NO answer is obtained in step  403 , and the routine proceeds to step  408  wherein the display  8  indicates instructions to go to the test station  20 . After the driver of the vehicle confirms the indication on the display  8 , the driver takes the error card out of the toll payment error card distributor or pushes the gate opening manual switch installed in the gate opening device  11 , for example, for opening the gate  10 . 
     The routine proceeds to step  409  wherein the lane control computer  30  monitors the operation of the gate opening device  11  to determine whether the driver has confirmed the indication on the display  8  or not. If a YES answer is obtained, then the routine proceeds to step  410  wherein upon opening of the gate  10 , the monitor camera  13  is activated to photograph the vehicle including a license plate and/or the driver which has operated the gate opening device  11 . The routine proceeds to step  411  wherein the gate  10  is opened. 
     FIG. 8 shows the control device  60  installed in the test station  20 . The control device  60  includes the test station computer  24  which controls operations of the testing unit  21 , the gate  23 , the vehicle type identifying device  25 , the cameras  26 , the display  27 , and the vehicle detector  28 . 
     The vehicle type identifying device  25  is mounted in front of the toll house  22  and detects a vehicle passing therethrough and identifies the type of the vehicle using a laser, as will be described later in detail. The cameras  26  are mounted near the vehicle type identifying device  25  and photographs the vehicle passing thereby. The display  27  is installed in a window of the toll house  22  to give the driver of the vehicle various instructions. The vehicle detector  28  detects the passage of the vehicle through the gate  23  and closes the gate  23 . 
     The test station computer  24  monitors communication between the testing unit  21  and the in-vehicle unit  40  to transmit to the toll house computer  29  troubleshooting information on measures to be taken to cure the abnormalities of the in-vehicle unit  40 . The test station computer  24  connects with the toll booth computer  100  and transmits information on the abnormalities or troubles of the in-vehicle unit  40  to the network  101 . 
     FIG. 9 shows an operation or program performed by the testing unit  21 . 
     Upon initiation of the program, the routine proceeds to step  501  wherein it is determined whether the error signal has been outputted from the in-vehicle unit  40  in step  208  of FIG. 4 or not. If a NO answer is obtained, then the routine performs step  501  again after a predetermined period of time. Alternatively, if a YES answer is obtained, then the routine proceeds to step  502  wherein the testing unit  21  reads the error information recorded in step  306  of FIG. 6 out of the toll collecting unit  31  installed on one of the ETC lanes  1  through which the vehicle having outputted the error signal has passed. The routine proceeds to step  503  to determine which of the conditions (1) to (5), as indicated in FIG. 6, the error information shows. 
     If the condition (4) is encountered meaning that the in-vehicle unit  40  is in the normal condition, but it is impossible to collect tolls from the in-vehicle unit  40 , then the routine proceeds to step  504  wherein the toll payment request signal is outputted to the in-vehicle unit  40 . 
     The routine proceeds to step  505  wherein it is determined whether the payment completion signal has been outputted from the in-vehicle unit  40  or not. If a YES answer is obtained, then the routine proceeds to step  506  wherein a command is issued for the in-vehicle unit  40  to display the fact that the payment completion signal has been received by the toll collecting unit  31 . The routine proceeds to step  507  wherein the operation in step  506  is recorded. 
     If a NO answer is obtained in step  505 , then the routine proceeds to step  508  wherein a retry operation is performed to output the toll payment request signal again to the in-vehicle unit  40 . If the payment completion signal is still not outputted from the in-vehicle unit  40  after the toll payment request signal is outputted a given number of times, then the routine proceeds to step  507  wherein the communication with the in-vehicle unit  40  is disrupted, and the fact thereof is recorded. 
     If the condition (3) is encountered meaning that the in-vehicle unit  40  is in the abnormal condition, and it is impossible to collect tolls from the in-vehicle unit  40 , then the routine proceeds to step  509  wherein a test(s) is selected which corresponds to the abnormality or trouble of the in-vehicle unit  40  as indicated by the status data. The routine proceeds to step  510  wherein a test command is issued for the in-vehicle unit  40  to conduct the test(s) selected in step  509 . The routine proceeds to step  510  wherein it is determined whether the in-vehicle unit  40  operates correctly under the test(s) or not by monitoring an output from the in-vehicle unit  40 . If a NO answer is obtained, then the routine proceeds to step  512  wherein the fact that the in-vehicle unit  40  is in the abnormal condition is recorded. After step  512  or if a YES answer is obtained in step  511 , then the routine proceeds to step  513  wherein it is determined whether the test(s) has been finished or not. If a YES answer is obtained, then the routine proceeds to step  514  wherein the results of the test(s) are recorded. 
     If the condition (5) is encountered meaning that the in-vehicle unit  40  is in the abnormal condition, but it is possible to collect tolls from the in-vehicle unit  40 , then the routine proceeds to step  515  wherein the status data of the in-vehicle unit  40  is monitored to determine whether the unauthorized case opening flag which indicates the possibility of unauthorized disassembling of the in-vehicle unit  40  is set or not, that is, whether there is a possibility that the data in the in-vehicle unit  40  is altered or not. If the unauthorized case opening flag is set, then the routine proceeds to step  516  wherein the possibility of unauthorized disassembling of the in-vehicle unit  40  and an ID number of the in-vehicle unit  40  are recorded. Alternatively, if a NO answer is obtained in step  515 , then the routine proceeds to step  517  wherein the toll payment request signal is outputted to the in-vehicle unit  40 . The routine proceeds to step  518  wherein it is determined whether the payment completion signal has been outputted from the in-vehicle unit  40  or not. If a YES answer is obtained, then the routine proceeds to step  519  wherein a command is issued for the in-vehicle unit  40  to display the fact that the payment completion signal has been received by the toll collecting unit  31  and contents of the abnormality or trouble of the in-vehicle unit  40 . The routine proceeds to step  516  wherein the operation in step  519  is recorded. 
     If a NO answer is obtained in step  518 , then the routine proceeds to step  520  wherein a retry operation is performed to output the toll payment request signal again to the in-vehicle unit  40 . If the payment completion signal is still not outputted from the in-vehicle unit  40  after the toll payment request signal is outputted a given number of times, then the routine proceeds to step  516  wherein the communication with the in-vehicle unit  40  is disrupted, and the fact thereof is recorded. 
     After step  507 ,  514 , or  516 , the routine proceeds to step  512  in FIG. 10 wherein it is determined whether information recorded in step  306  of FIG. 6 is identical with that recorded in step  507 ,  514 , or  516  or not, that is, whether the contents of the abnormality or trouble of the in-vehicle unit  40  as determined by the toll collecting unit  31  agree with those determined in the operation of FIG. 9 or not. If a YES answer is obtained, then the routine returns back to step  502  of FIG.  9 . Alternatively, if a NO answer is obtained, for example, if it was impossible to collect tolls from the in-vehicle unit  40  through the toll collecting unit  31 , but the tolls has been collected from the in-vehicle unit  40  by the testing unit  21  at the test station  20 , then the routine proceeds to step  522  wherein it is determined whether the number of the in-vehicle units  40  which caused the negative answer in step  521  for a predetermined period of time in each of the ETC lanes  1  is greater than a given value or not. If a YES answer is obtained concluding that the control device  55  installed in one of the ETC lanes  1  which has caused the positive answer in step  522  is malfunctioning, then the routine proceeds to step  523  wherein a trouble signal indicative of the malfunction of the control device  55  is outputted to the test station computer  24 . The test station computer  24  informs the toll booth computer  100  of the malfunction of the control device  55  for troubleshooting. 
     FIG. 11 shows an operation or program performed by the test station computer  24 . 
     Upon initiation of the program, the routine proceeds to step  601  to close the gate  23 . The routine proceeds to step  602  wherein it is determined whether the vehicle has come in front of the toll house  22  or not based on an output signal from the vehicle type identifying device  25 . If a YES answer is obtained, then the routine proceeds to step  603  wherein the output signal from the vehicle type identifying device  25  is monitored to determine the type of the vehicle. 
     The routine proceeds to step  604  wherein it is determined whether the communication has already been established between the vehicle and the testing unit  21  or not. If a NO answer is obtained concluding that the vehicle detected by the vehicle type identifying device  25  does not have mounted therein the in-vehicle unit  40 , then the routine proceeds to step  605  wherein the test station computer  24  turns on the cameras  26  to capture an image of the appearance of the vehicle and transmits information that the vehicle does not have the in-vehicle unit  40  and the captured image to the toll house computer  29 . The toll house computer  29  issues a command for the display  27  to indicate the information transmitted from the test station computer  24  visually. A toll keeper sees the indication on the display  27 , collects required tolls from a driver of the vehicle manually, and opens the gate  23  to allow the vehicle to return to the roadway. 
     If a YES answer is obtained in step  604 , then the routine proceeds to step  606  whether it is determined whether the testing unit  21  has collected tolls from the in-vehicle unit  40  correctly or not. If a YES answer is obtained, then the routine proceeds to step  607  wherein the fact that the testing unit  21  has collected tolls from the in-vehicle unit  40  correctly is indicated through the display  27  and communicated to the toll house computer  29 . The routine proceeds to step  608  to open the gate  23 . The routine proceeds to step  609  wherein it is determined whether the vehicle has passed the gate  23  or not based on an output signal from the vehicle detector  28 . If a YES answer is obtained, then the routine returns to step  601 . 
     If a NO answer is obtained in step  606  meaning that the testing unit  21  could not collect tolls from the in-vehicle unit  40  correctly, then the routine proceeds to step  610  wherein a command is issued for the display  27  to indicate that the in-vehicle unit  40  is in the abnormal condition, and information on communication between the testing unit  21  and the in-vehicle unit  40  is transmitted to the toll house computer  29 . The toll house computer  29  displays and informs the toll keeper in the toll house  22  of troubleshooting information. The toll keeper takes measures, as discussed later in detail. 
     The vehicle type identifying device  25  includes the laser unit  50 , as shown in FIG.  12 . 
     The laser unit  50  consists of a laser transceiver, a signal processing circuit, and an external interface (not shown). The laser transceiver has a polygon mirror which scans a laser beam over a given detection zone in front of the toll house  22 . 
     In operation, the laser unit  50  emits a laser beam. The laser beam is reflected on an object such as a road surface and returns to the laser transceiver of the laser unit  50 . The laser unit  50  determines the amount of time required by the laser beam to travel to and return from the object. When a vehicle enters the detection zone, the laser beam emitted from the laser unit  50  is reflected by the vehicle. Since the vehicle is closer to the laser unit  50  than the road surface, the amount of time required by the laser beam to travel to and return from the vehicle becomes shorter than that when there is no vehicle within the detection zone. This time difference is measured to determine the passage of the vehicle through the detection zone. 
     The laser unit  50  also determines the distance to the vehicle based on the amount of time required by the laser beam to travel to and return from the vehicle and analyzes an angular range occupied by the laser beam reflected from the vehicle to determine the size of the vehicle or identify the type of the vehicle. For example, a three-dimensional image of the vehicle may be produced using a change in distance to the vehicle measured through scans of the laser beam over the whole of the vehicle to identify the type thereof. 
     The speed of the vehicle passing through the detection zone may be measured by analyzing laser beams reflected from two points defined in the detection zone to calculate the amount of time required by the vehicle to travel between the two points. 
     The laser unit  50  also includes the transceiver  51  which communicates with the in-vehicle unit  40  to receive vehicle type information therefrom and transmits it to the test station computer  24  together with the above information on the vehicle entering the detection zone. The test station computer  24  determines whether the type of the vehicle indicated by the vehicle type information agrees with the one identified by the laser unit  50  or not. If a NO answer is obtained, the test station computer  24  informs the toll booth computer  100  of the disagreement of the type of the vehicle indicated by the vehicle type information with the one identified by the laser unit  50 . When the status data of the in-vehicle unit  40  indicates an error in the type of the vehicle, the toll collecting unit  31  concludes that the in-vehicle unit  40  is malfunctioning and that it is impossible to collect tolls from the in-vehicle unit  40 . In this case, if the type of the vehicle identified by the laser unit  50  agrees with the one indicated by the vehicle type information of the in-vehicle unit  40 , then the test station computer  24  concludes that the toll collecting unit  31  is malfunctioning. When this conclusion is made a given number of times, the test station computer  24  outputs a trouble signal to the toll booth computer  100  to inform of the malfunction of the toll collecting unit  31 . The toll collecting unit  31  takes a preselected measure to cure the malfunction of the toll collecting unit  31 . 
     The transceiver  51  is able to communicate with the in-vehicle unit  40  within an area (i.e., a downlink area) where a signal from the transceiver  51  reaches the in-vehicle unit  40 , however, it is advisable that the transceiver  51  be controlled so as to communicate with the in-vehicle unit  40  within part of the downlink area (i.e., an uplink area) where the in-vehicle unit  40  is able to communicate with the transceiver  51  with high quality. The laser unit  50 , thus, emits a laser beam  53 , as shown in FIG. 12, to a front end of the uplink area and a laser beam  54  to a rear end of the uplink area. When the two laser beams  53  and  54  both detect the vehicle, the transceiver  51  starts to communicate with the in-vehicle unit  40  for establishing high-quality communication therebetween. 
     The toll house computer  29 , as described above, receives the information on abnormalities of the in-vehicle unit  40  from the test station computer  24  and displays the troubleshooting information. The toll keeper removes the in-vehicle unit  40  from the vehicle and takes a preselected measure. For example, when the test station computer  24  indicates that the in-vehicle unit  40  is malfunctioning, the toll keeper replaces the in-vehicle unit  40 . Alternatively, when the test station computer  24  indicates the possibility of the data in the in-vehicle unit  40  being altered, the toll keeper questions the driver about the data alteration of the in-vehicle unit  40 . 
     The in-vehicle unit  40  withdrawn by the toll keeper is checked to locate causes of the abnormalities and repaired. An in-vehicle unit adjusting device  60 , as shown in FIG. 13, is installed in the toll house  22  which is designed to reprogram or rewrite data in the in-vehicle unit  40 . 
     The in-vehicle unit adjusting device  60  includes an electromagnetic wave-shielding box  61 , an antenna  62 , a CCD camera  63 , and a controller  64 . The antenna  62  and the CCD camera  63  are installed in the electromagnetic wave-shielding box  61  and connect with the controller  64 . The CCD camera  63  monitors the man/machine interface of the in-vehicle unit  40 . The controller  64  is designed to be loaded from a control program storage device with programs needed to adjust the in-vehicle unit  40  and allow required one of the programs to be selected manually. For security purposes, it is advisable that the controller  64  be designed to operate in response to input of a password or insertion of an IC card for allowing specified users to gain access to data in the controller  64 . 
     The controller  64  gives the in-vehicle unit  40  instructions as represented by a selected program to execute a predetermined sequence of operations and analyzes results of the operations to determine and display the status of the in-vehicle unit  40 . An image captured by the CCD camera  63  is indicated on a display of the controller  64  to determine whether the man/machine interface is normal or not. The controller  64  records therein the status of the in-vehicle unit  40  and an ID number thereof. 
     If the in-vehicle unit  40  was disassembled by an unauthorized person, it is recorded in the status data, as shown in FIG.  5 . The controller  64  can analyze the status data to know whether the in-vehicle unit  40  was disassembled to alter data thereof or not. For example, if an unauthorized person tried to disassemble the in-vehicle unit, but gave up without altering the data, only the status data is changed. In this case, rewriting the status data allows the in-vehicle unit  40  to be used again. 
     Even if the in-vehicle unit adjusting device  60  determines that the status of the in-vehicle unit  40  is normal, it may become impossible for the in-vehicle unit  40  reinstalled in the vehicle to communicate with the toll collecting unit  31 . This is because radio waves radiated from the in-vehicle unit  40  attenuate greatly due to the shape of a hood and a wind shield glass of the vehicle and the location where the in-vehicle unit  40  is mounted. For avoiding this problem, a portable in-vehicle unit adjusting device, as shown in FIG. 14, which is capable of adjusting the in-vehicle unit  40  mounted in the vehicle in the same manner as that of the in-vehicle unit adjusting device  60  may be employed. The portable in-vehicle unit adjusting device includes the antenna  65 , the display  65 , and the manual switch  67  and is connected to the controller  64 . 
     FIG. 15 shows an automatic toll collection system according to the second embodiment of the invention which is different from the first embodiment in that the test station  20  is provided in front of the toll booth for checking the status of the in-vehicle unit  40  before the vehicle enters either of the ETC lanes  1 . In the first embodiment, when a vehicle which has past through the central ETC lane  1  goes to the test station  20 , it is necessary to pay attention to a traffic flow from the left ETC lane  1 , thus causing traffic congestion at the exit of the central ETC lane  1 . This embodiment is aims at alleviating this problem. 
     A pre-toll collecting unit  70  is mounted on, for example, a ramp in front of the toll booth which serves to check the status data of the in-vehicle unit  40  of each vehicle and collect tolls therefrom. Each ETC lane  1  confirms whether the in-vehicle unit  40  of each vehicle has completed the payment of tolls or not. 
     When the pre-toll collecting unit  70  detects an abnormality of the in-vehicle unit  40 , it issues a command for a display (not shown) mounted behind the pre-toll collecting unit  70  to indicate “Go to Test Station”. The test station  20  troubleshoots the in-vehicle unit  40  in the same manner as that in the first embodiment. 
     The pre-toll collecting unit  70  may alternatively be designed to check the status data of the in-vehicle unit  40  only without collecting the tolls. In this case, each ETC lane  1  collects the tolls from each vehicle in the same manner as that in the first embodiment. 
     While the present invention has been disclosed in terms of the preferred embodiment in order to facilitate a better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modification to the shown embodiments which can be embodied without departing from the principle of the invention as set forth in the appended claims.