Vehicle-to-vehicle communication device for communication with other vehicles and method for communication between vehicles

Abstract

Vehicle-to-vehicle communication device for a vehicle, the device comprising: - a transmitting element (22) for transmitting information about the vehicle to another vehicle in a predetermined transmission period; - a transmission control unit (16, 18) for controlling the transmission element; - a vehicle speed obtaining element for obtaining a speed of the vehicle; - a computing device (14, 16) for calculating the transmission period such that the transmission period becomes shorter as the speed of the vehicle increases; - a detector (24) for detecting a state of a display device (5a) in the vehicle; and - a speed determining element for determining whether the speed of the vehicle is greater than a predetermined speed, wherein - the display device (5a) informs a person around the vehicle about a condition and presence of the vehicle, and - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in a period shorter than the predetermined period calculated by the calculation device (14, 16) according to the speed of the vehicle when the detector (24) detects that the display device (5a) is operating and the speed determination element determines that the speed of the vehicle is not greater than the predetermined speed.

Description

[0001] The present invention relates to a vehicle-to-vehicle communication device for communicating with other vehicles and a method for communicating between vehicles.

[0002] A vehicle-to-vehicle communication device is mounted on a vehicle. The device transmits information, such as information about the position of the vehicle, to other vehicles located around the vehicle. Furthermore, the device receives information, such as information about the position of another vehicle, from the other vehicle.

[0003] JP 2000-90395 A discloses a device that transmits information about a vehicle in a short period when the vehicle is traveling at high speed. The device transmits the information in a long period when the vehicle is traveling at low speed.

[0004] Suppose that two vehicles traveling on the same road are approaching each other. If at least one of the vehicles is traveling at a low speed, the device disclosed in JP 2000-90395 A in that vehicle, i.e., the slow-moving vehicle, transmits the information over a long period. As a result, the other vehicle may receive the information from the slow-moving vehicle late. Consequently, a driver in the other vehicle may detect the presence of the slow-moving vehicle late. If traffic is congested on the road and vehicles are stopped or traveling at a very slow speed, if another vehicle approaches the vehicles from behind, the other vehicle may collide with the rearmost vehicle.

[0005] The rearmost vehicle travels at a very low speed and is located at the rear of the vehicles.

[0006] Furthermore, when a vehicle turns right or left, it may be traveling at a low speed or temporarily stopping. In this case, the device in the vehicle transmits the information over a long period of time. As a result, another vehicle may receive the information late. Consequently, a driver in the other vehicle may be late in detecting the presence of the vehicle turning left or right.

[0007] The inventors of the present invention have investigated the above situation. Fig. 7A and Fig. 7B show the situations described above. In the Fig. 7A, the three vehicles A, B, C are stopped or the three vehicles A, B, C are traveling at very low speed. Very low speed means that the vehicle is traveling at walking pace. The three vehicles A, B, C form a group of slow-moving vehicles. Another vehicle D is approaching the group of slow-moving vehicles from behind the slow-moving vehicles. If an inter-vehicle communication device in one of the slow-moving vehicles A, B, C sends information to the other vehicle D over a long period of time, a driver of the other vehicle D may be late in detecting the presence of the slow-moving vehicles A, B, C.

[0008] In the Fig. 7B, vehicles EG approach the same intersection. A vehicle G stops at the intersection to turn left at the intersection after two vehicles E, F have passed through the intersection. Alternatively, vehicle G may enter the intersection at a very low speed. If an inter-vehicle communication device in vehicle G sends information to the other vehicles E, F over a long period, a driver in the other vehicles E, F may be late in detecting the presence of vehicle G.

[0009] Further relevant prior art is known from DE 10 2005 059 688 A1 and DE 102 18 652 A1.

[0010] It is therefore an object of the present invention to provide a vehicle-to-vehicle communication device for communicating with other vehicles. It is also an object of the present invention to provide a method for communication between vehicles.

[0011] The object is achieved by a vehicle-to-vehicle communication device for communication with other vehicles having the features of claim 1 and by a method for communication between vehicles having the features of claim 13 or 14.

[0012] According to a first aspect of the present invention, there is provided a vehicle-to-vehicle communication device for a vehicle, comprising: a transmitting element for transmitting information about the vehicle to another vehicle at a predetermined period; a transmitting control unit for controlling the transmitting element; and a detector for detecting a state of a display device in the vehicle. The display device informs a person around the vehicle of a state and presence of the vehicle, and the transmitting control unit controls the transmitting element to transmit the information at a period shorter than the predetermined period when the detector detects that the display device is operating.

[0013] The indicator device indicates the status and presence of the vehicle to the vehicles. Since the transmission control unit controls the transmitting element to transmit the information at a period shorter than the predetermined period, when the detector detects that the indicator device is operating, other vehicles are immediately informed of the vehicle's presence.

[0014] According to a second aspect of the present invention, a method for communication between vehicles is provided, comprising the following steps: obtaining information about a vehicle; detecting a speed of the vehicle; calculating a transmission period as a first transmission period when the speed of the vehicle is less than or equal to a predetermined value; calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, wherein the second transmission period is shorter than the first transmission period; transmitting the information about the vehicle to another vehicle in the calculated transmission period; determining whether a hazard warning light is turned on; determining whether the speed of the vehicle is above the predetermined value; maintaining the calculated transmission period if the hazard warning light is not turned on or the vehicle speed is above the predetermined value;and changing the calculated transmission period to the second transmission period when the hazard warning light is turned on and the vehicle speed is less than or equal to the predetermined value;

[0015] According to the above procedure, the other vehicles are immediately informed of the presence of the vehicle.

[0016] According to a third aspect of the present invention, a method for communication between vehicles is provided, comprising the steps of: obtaining information about a vehicle; detecting a speed of the vehicle; calculating a transmission period as a first transmission period when the speed of the vehicle is less than or equal to a predetermined value; calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, the second transmission period being shorter than the first transmission period; transmitting the information about the vehicle to another vehicle in the calculated transmission period; determining whether a turn signal is turned on; determining whether a braking device is operating; determining whether the speed of the vehicle is above the predetermined value;Maintaining the calculated transmission period when the turn signal is not turned on, the braking device is not operating, or the vehicle speed is above the predetermined value; and changing the calculated transmission period to the second transmission period when the turn signal is turned on, the braking device is operating, and the vehicle speed is less than or equal to the predetermined value.

[0017] According to the above procedure, the other vehicles are immediately informed of the presence of the vehicle.

[0018] The above and other features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: Fig. 1 is a block diagram of an in-vehicle device (i.e., vehicle-to-vehicle communication device); Fig. 2 a block diagram of a navigation system; Fig. 3 is a flowchart showing a transmission period control process executed by an information determining element in the vehicle device according to a first embodiment; Fig. 4 is a diagram illustrating a function of the vehicle device of the first embodiment; Fig. 5 is a flowchart showing another transmission period control process executed by the information determining element in the vehicle device according to a second embodiment; Fig. 6 is a diagram illustrating a function of the vehicle device of the second embodiment; and Fig. 7A and Fig. 7B Illustrations of exemplary situations to illustrate the disadvantages of the prior art. (First embodiment)

[0019] Fig. 1 shows a vehicle device 1 according to a first embodiment. The device 1 is mounted on a vehicle and includes a first communication means 10, an antenna 11, a first packet receiving element 12, a packet receiving buffer 14, a table storage medium 15, a transmission period control unit 16, an information determination element 18, a data generation element 19, a packet transmission buffer 20, a first packet transmission element 22, a second communication means 24, a second packet receiving element 26, and a second packet transmission element 28.

[0020] The device 1 is connected to a vehicle network (in-vehicle network) 3 in such a way that it can communicate, for example, with a navigation system 2, a brake ECU 4 for controlling a braking device 4a, and a vehicle ECU (body ECU) 5 for controlling a turn signal 5a, i.e., a direction indicator. The turn signal 5a also serves as a hazard warning light. The turn signal 5a serves, for example, as a hazard warning light when the right and left direction indicators flash simultaneously.

[0021] Fig. 2 shows the navigation system 2. The navigation system 2 includes a position detector 101, operation switches 103, a map data input element 104, a display 105, an audio output element 106, an external information input / output element (hereinafter referred to as an I / O element) 107, and a control unit 102. The position detector 101 detects the current position of the vehicle. A user of the navigation system 2 inputs various commands via the operation switches 103. The user is, for example, a driver or a passenger of the vehicle. Map data and other information are input to the navigation system 2 from an external storage medium via the map data input element 104. The display 105 displays map data and various information images, such as a television image. The audio output element 106 outputs various sounds, such as voice guidance.The control unit 102 performs various processes based on the information input from the position detector 101, the operation switches 103, the map data input element 104, and the I / O element 107. Furthermore, the control unit 102 controls the position detector 101, the operation switches 103, the map data input element 104, the display 105, the sound output element 106, and the I / O element 107.

[0022] The position detector 101 includes a GPS (Global Positioning System) receiver 101a, a gyroscope 101b, and a distance sensor 101c. The GPS receiver 101a receives a radio wave from a GPS satellite via a GPS antenna (not shown) so that it can detect the current position, orientation, and speed of the vehicle, and the like. The gyroscope 101b detects an amount of torque applied to the vehicle. The distance sensor 101c detects a traveled distance of the vehicle based on acceleration in the traveling direction (front-back direction) of the vehicle, and the like. Since the GPS receiver 101a, the gyroscope 101b, and the distance sensor 101c have errors of different natures, the GPS receiver 101a, the gyroscope 101b, and the distance sensor 101c are used, complementing each other.

[0023] The switches 103 are integrated into the display 105. The switches 103 include a touch-sensitive switch on a touch-sensitive panel of the display 105 and a mechanical switch arranged around the display 105. The touch-sensitive switch is displayed on a screen of the display 105. The touch-sensitive panel is integrated into the display 105 such that the touch-sensitive panel and the display 105 are layered together to form a single unit. The touch-sensitive panel can be a pressure-sensitive panel, an electromagnetic inductive panel, a capacitive panel, or a combination of these panels.

[0024] The map data input element 104 is used to input the map data stored on the storage medium. The map data includes, for example, road section data, node data for indicating an intersection, map matching data for improving the accuracy of determining the current position of the vehicle, landmark data for indicating facilities, image data for route guidance, audio data, and the like. The storage medium for the map data can be a CD-ROM, a DVD, a hard disk, or a memory card.

[0025] The display 105 may be a color display device such as a liquid crystal display, a plasma display, or a CRT display. The display 105 displays a screen image including a map image, a vehicle marker, a guide route to a destination, a name such as a place name, a landmark, a facility marker, and the like, which overlap with each other. The vehicle marker indicates the current position of the vehicle on the map image, and the current position is determined using the map data input via the map data input element 104 and the current position of the vehicle detected by the position detector 101. In this case, the name, the landmark, and the facility marker constitute additional data. Furthermore, the screen image may include guidance for a specific facility.

[0026] The sound output element 106 outputs a voice signal for facility guidance, the information for which is input via the map data input element 104. The element 106 also outputs an audible signal for various guidance and a voice message for information received via the I / O element 107.

[0027] The I / O element 107 transmits information to the vehicle network 3 and receives information from the vehicle network 3. Furthermore, the element 107 can receive an FM and / or AM broadcast signal via a radio antenna (not shown). The element 107 can receive a radio beacon signal and an optical beacon signal from a fixed station of a vehicle information and communication system (i.e., VICS) located near a road. The received information is provided to the control unit 102 for processing by the control unit 102. Furthermore, a connection to the Internet can be established via the element 107.

[0028] The control unit 102 includes a conventional microcomputer with a CPU, a ROM, a RAM, an I / O unit, and a bus line. The bus line connects the CPU, the ROM, the RAM, and the I / O unit. According to a program stored in the ROM, the control unit 102 calculates the current position of the vehicle based on a detection signal from the position detector 101. The current position is determined as a combination of coordinates and the traveling direction. The control unit 102 also serves to display the map image on the display 105, the map image representing a portion of the map within the vehicle's area read from the map data input element 104. The control unit 102 selects a destination from point data stored in the map data input element 104 in accordance with an operation of the switches 103.The control unit 102 automatically calculates an optimal route from the current position of the vehicle to the destination.

[0029] In the Fig. 1, the in-vehicle device 1 receives information about the current position, traveling direction, and vehicle speed of the vehicle, as well as map data in the area of ​​the vehicle, from the navigation system 2, wherein the information is calculated by the navigation system 2. The in-vehicle device 1 also receives information about an operating state of the brake device 4a from the brake ECU 4. The in-vehicle device 1 receives information about an operating state of the turn signal 5a. In this case, the information about the own vehicle received from the navigation system 2, the brake ECU 4, the vehicle ECU 5, and the in-vehicle network 3 via the communication means 24 is defined as own-vehicle information. The in-vehicle device 1 periodically receives the own-vehicle information.

[0030] The own vehicle information received via the communication means 24 is provided as an information packet and sent to the second packet receiving element 26. The second packet receiving element 26 writes the own vehicle information into the packet receiving buffer 14. Consequently, the own vehicle information received from the navigation system 2 via the vehicle network 3 is stored in the packet receiving buffer 14.

[0031] The vehicle device 1 receives information about other vehicles located within the vehicle's range or traveling within the vehicle's range wirelessly from the vehicle devices in the other vehicles via the antenna 11 and the communication means 10. The information is provided as an information packet. The information about the other vehicles includes the current position, direction of travel, and vehicle speed of each of the other vehicles. In this case, the information about the other vehicles is defined as other vehicle information.

[0032] The other vehicle information received via the antenna 11 and the communication means 10 is provided as an information packet and sent to the first packet receiving element 12. The first packet receiving element 12 writes the other vehicle information into the packet receiving buffer 14. Consequently, the packet receiving buffer 14 stores the other vehicle information received from the other vehicle within the range of the own vehicle.

[0033] The data generation element 19 generates own vehicle data based on the own vehicle information stored in the packet reception buffer 14, wherein the own vehicle data is transmitted to the other vehicles. The data generation element 19 writes the own vehicle data to the packet transmission buffer 20. The data generation element 19 further generates other vehicle data based on the other vehicle information stored in the packet reception buffer 14, wherein the other vehicle data is transmitted to the navigation system 2 and / or the vehicle network 3. The data generation element 19 writes the other vehicle data to the packet transmission buffer 20.

[0034] The second packet transmission element 28 reads predetermined information to be sent to the navigation system 2 and / or the vehicle network 3 from the third-party vehicle data stored in the packet transmission buffer 20. The second packet transmission element 28 sends the read third-party vehicle data to the navigation system 2 and / or the vehicle network 3 via the communication means 24.

[0035] The first packet transmission element 22 reads the own vehicle data stored in the packet transmission buffer 20. The first packet transmission element 22 transmits the read own vehicle data via the communication means 10 and the antenna 11 by radio to the other vehicles in the vehicle's area.

[0036] The transmission period control unit 16 controls a transmission period of the first packet transmitting element 22. Specifically, the control unit 16 reads information about the vehicle speed of the host vehicle from the information stored in the packet receiving buffer 14. Based on the vehicle speed, the control unit 16 calculates an optimal transmission period. In this case, the control unit 16 calculates the optimal transmission period by referring to a table stored in the table storage medium 15. The table defines a relationship between the vehicle speed and the optimal transmission period. In the table on the table storage medium 15, as the vehicle speed increases, the optimal transmission period becomes shorter.

[0037] The transmission period control unit 16 issues a command to the first packet transmitting element 22 so that the first packet transmitting element 22 transmits information at the calculated optimal transmission period. The first packet transmitting element 22 transmits the own-vehicle information at the optimal transmission period instructed by the transmission period control unit 16.

[0038] The information determination element 18 carries out a Fig. 3 periodically executes the transmission period control process shown. In step S110 of the process, the element 18 obtains the own vehicle information stored in the packet reception buffer 14.

[0039] In step S120, element 18 calculates an optimal transmission period determined by the vehicle speed based on the vehicle speed information in the own vehicle information. Specifically, element 18 refers to the table on table storage medium 15 to calculate the optimal transmission period.

[0040] In step S130, the element 18 controls the first packet transmitting element 22 to transmit the own-vehicle information to the other vehicles at the calculated transmission period. Consequently, inter-vehicle communication is performed via the first packet transmitting element 22.

[0041] In step S140, the element 18 determines whether the hazard warning light 5a of the own vehicle is turned on based on the own vehicle information.

[0042] If the element 18 determines that the hazard warning light 5a is turned on, that is, "Yes" in step S140, the processing proceeds to step S150. In step S150, the element 18 determines whether the vehicle speed of the host vehicle is above a predetermined value.

[0043] If the element 18 determines that the vehicle speed is above the predetermined value, that is, "Yes" in step S150, the processing proceeds to step S160. In step S160, the element 18 outputs a command indicating that the transmission period will not be changed to the transmission period control unit 16. In this case, the transmission period control unit 16 outputs a command to the first packet transmission element 22, and the command to transmit the own vehicle information is not changed. Specifically, the transmission period of the first packet transmission element 22 remains at the optimal transmission period determined based on the vehicle speed of the own vehicle. Following step S160, the transmission period control process is terminated.

[0044] In step S150, if the element 18 determines that the vehicle speed is less than or equal to the predetermined value, that is, "No" in step S150, the processing proceeds to step S170. In step S170, the element 18 issues a transmission period change command to the transmission period control unit 16. Specifically, the command of the element 18 is to change the transmission period to another optimal transmission period according to the high vehicle speed exceeding the predetermined value. In this case, since the hazard warning light 5a is turned on, it is necessary to inform the other drivers in the other vehicles within the range of the own vehicle of the presence of the own vehicle. Consequently, the information transmission period is shortened. Following step S170, the transmission period control process is terminated.

[0045] In step S140, if the element 18 determines that the hazard warning light 5a will not be turned on, that is, "No" in step S140, the processing proceeds to step S160. In step S160, the element 18 outputs the command indicating that the transmission period will not be changed to the transmission period control unit 16.

[0046] Fig. 4 shows a specific situation to illustrate a function of the vehicle device 1. The vehicles a, b, c are approaching the same intersection X1 at low speed. The hazard warning light 5a of the vehicle c is turned on to warn a driver in another vehicle d approaching the vehicle c from an area behind the vehicle c, so that the other vehicle d does not collide with the vehicle c.

[0047] Each of the vehicles a, b, and c includes the in-vehicle device 1, so that inter-vehicle communication is performed among the vehicles a, b, and c. Specifically, information from one vehicle is transmitted to the other two vehicles. In this case, the transmission period of the in-vehicle device 1 is controlled as follows.

[0048] In step S120, the in-vehicle device 1 in each of the vehicles a, b, and c calculates the transmission period in accordance with the low vehicle speed, so that the transmission period is long. Specifically, the transmission period control unit 16 obtains information from the table storage medium 15 so that the transmission period is calculated according to the low speed. In step S130, the control unit 16 sends a command to the first packet transmitting element 22, so that the first packet transmitting element 22 transmits information with the calculated transmission period to the other vehicles.

[0049] In step S140, the in-vehicle device 1 in each of vehicles a, b, and c determines whether the hazard warning light 5a of the vehicle is turned on. In this case, the in-vehicle devices 1 of vehicles a, b determine that the hazard warning light 5a is not turned on, i.e., "No" in step S140. Consequently, the processing proceeds to step S160, so that the in-vehicle device sets the long transmission period corresponding to the low vehicle speed. The in-vehicle device 1 of vehicle c determines that the hazard warning light 5a is turned on, i.e., "Yes" in step S140. Consequently, the processing proceeds to step S170, so that the in-vehicle device 1 sets the short transmission period.

[0050] If the vehicle c has a low speed and the hazard warning light 5a of the vehicle c, as shown in Fig. 4, the transmission period of the in-vehicle device 1 in the vehicle c becomes short. When another vehicle d approaches the vehicles a, b, c from an area behind the vehicles a, b, c, the in-vehicle device 1 in the other vehicle d can acquire the information about the presence of the vehicle c from the in-vehicle device 1 in the vehicle c. Consequently, the in-vehicle device 1 in the other vehicle can acquire the presence of the vehicle c without a large time delay. Consequently, it is possible to prevent the presence of the vehicle c from being detected with a delay by the in-vehicle device 1 in the other vehicle d. For example, it is possible to prevent the other vehicle d from colliding with the vehicle c. In this way, the safety of the vehicles a, b, c, d can be improved.

[0051] The first packet transmission element 22 is a transmission element for executing step S130. The transmission period control unit 16 and the information determination element 18 constitute a transmission control unit for executing steps S160 and S170. A detection element for a warning element, such as the hazard warning light 5a, executes step S140. A transmission period calculation element executes step S120. (Second embodiment)

[0052] In a vehicle device 1 according to a second embodiment, the information determination element 18 performs the Fig. 5 periodically executes the transmission period control process.

[0053] In the Fig. 5, following step S130, processing proceeds to step S210. In step S210, the information determining element 18 determines whether the vehicle's turn signal 5a is operating based on the information of the own vehicle obtained in step S110. If the information determining element 18 determines that the turn signal 5a is operating, that is, "Yes" in step S210, processing proceeds to step S220.

[0054] In step S220, the information determining element 18 determines whether the braking device 4a of the vehicle is operating. Specifically, the braking device 4a is generating a braking force.

[0055] If the information determination element 18 determines that the braking device 4a is operating, that is, "Yes" in step S220, the processing proceeds to step S230. In step S230, the information determination element 18 determines whether the speed of the host vehicle is above a predetermined value.

[0056] If the information determination part 18 determines that the speed of the own vehicle is above the predetermined value, that is, "Yes" in step S230, the processing proceeds to step S240. In step S240, the part 18 outputs a command indicating that the transmission period will not be changed to the transmission period control unit 16. In this case, the transmission period control unit 16 outputs a command to the first packet transmission part 22, and the command to transmit the own vehicle information is not changed. Specifically, the transmission period of the first packet transmission part 22 remains at the optimal transmission period determined based on the speed of the own vehicle. Following step S240, the transmission period control process is terminated.

[0057] In step S230, when the element 18 determines that the vehicle speed is less than or equal to the predetermined value, ie, "No" in step S230, the processing proceeds to step S250.

[0058] In step S250, the element 18 issues a transmission period change command to the transmission period control unit 16. Specifically, the command from the element 18 is to change the transmission period to another optimal transmission period according to the high vehicle speed exceeding the predetermined value. Since the turn signal 5a is turned on and the brake device 54a is operating, the element 18 determines that the host vehicle is turning left or right, for example, or the element 18 determines that the host vehicle is changing lanes. Consequently, the information transmission period becomes shorter. Following step S250, the transmission period control process is terminated.

[0059] If the element 18 determines that the turn signal 5a is not operating, i.e., "No" in step S210, the processing proceeds to step S240. Further, if the element 18 determines that the brake device 4a is not operating, i.e., "No" in step S220, the processing proceeds to step S240. In step S240, the element 18 outputs a command indicating that the transmission period is not changed to the transmission period control unit 16. In this case, the transmission period of the first packet transmission element 22 remains at the optimal transmission period determined based on the vehicle speed of the host vehicle. Following step S240, the transmission period control process is terminated.

[0060] Fig. 6 shows a specific situation to illustrate a function of the vehicle device 1. In the Fig. 6, the vehicles eg approach an intersection X2. Two vehicles e, f pass the intersection X2 from an upper side in the Fig. 6 to a lower side in the Fig. 6. The other vehicle g intends to turn left at intersection X2 after the two vehicles e and f have passed intersection X2. Vehicle g temporarily stops at intersection X2 or enters intersection X2 at low speed.

[0061] The in-vehicle device 1 in the other vehicle g calculates the transmission period in accordance with the low vehicle speed because the host vehicle is traveling at a low speed or temporarily stopping. In this case, the transmission period becomes long because the transmission period is calculated based on the low vehicle speed. Specifically, the transmission period control unit 16 obtains the information from the table storage medium 15 so that the transmission period is calculated according to the low speed. The control unit 16 sends a command to the first packet transmitting element 22 so that the first packet transmitting element 22 transmits information to the other vehicles in the calculated transmission period.

[0062] The vehicle device 1 in the other vehicle g detects that the turn signal 5a of the vehicle is operating, that is, a turn signal 5a on the left side of the vehicle is turned on to signal a left turn, corresponding to YES in step S210. Further, the device 1 detects that the brake device 4a is operating, that is, "Yes" in step S220. When the vehicle speed is over the predetermined value, the transmission period is set to be shorter compared to the long transmission period corresponding to the low vehicle speed. This process corresponds to NO in steps S230 and S250.

[0063] If the other vehicle g, as in Fig.6, enters the intersection at low speed or stops at the intersection X2 to turn left, and the turn signal 5a operates to signal a left turn and the brake device 4a operates, the transmission period of the in-vehicle device 1 in the other vehicle g becomes short. Consequently, the in-vehicle devices 1 of the two vehicles e, f can detect the presence of the other vehicle g when approaching the intersection X2. Consequently, the presence of the vehicle g can be prevented from being delayed or belatedly detected by the in-vehicle devices 1 in the other vehicles e, f. For example, the in-vehicle device 1 in the other vehicles e, f can be prevented from colliding with the other vehicle g. Consequently, the safety of the vehicles e, f, g can be improved.

[0064] Although the vehicle device 1 refers to the table on the table storage medium 15 so that the transmission period is calculated according to the vehicle speed, the vehicle device 1 may calculate the transmission period without referring to the table.

[0065] In the first embodiment, the vehicle device 1 determines whether the hazard warning light 5a is turned on, thereby controlling the transmission period. Alternatively, the vehicle device 1 may determine whether the brake device 4a is operating, thereby controlling the transmission period. Specifically, when the vehicle speed is low, the hazard warning light 5a is operating, and the brake device 4a is operating, the transmission period is set to be short.

[0066] The vehicle device serving as an inter-vehicle communication device may be configured as follows. In the device, when an indicator device such as a turn signal and a hazard warning light are operating and other vehicles are approaching the intersection to which the host vehicle is approaching, the transmission period is set to be short compared to a normal transmission period.

[0067] The display device can operate in conjunction with a gearshift lever. The gearshift lever selects a vehicle's movement state such that a drive position indicates forward movement of the vehicle, and a reverse position indicates rearward movement of the vehicle. When the reverse position is selected, the transmission period is shortened such that the presence of the vehicle is quickly reported to a person nearby.

[0068] Alternatively, the display device may be a monitor for monitoring the air pressure of a tire of the vehicle, so that the monitor determines whether the tire pressure is within a suitable value. Furthermore, if the tire pressure is not within a suitable value, the monitor issues an alarm. If the monitor determines that the tire pressure is outside a suitable range, the transmission period is shortened so that a person around the vehicle is quickly notified of the vehicle's emergency.

[0069] Alternatively, the transmission period may be changed in accordance with an operation time of the brake and / or the indicator device such as the turn signal, the hazard warning light, a shift lever indicator device, and the tire monitor.

[0070] For example, if the operating time is shorter than a predetermined time, it is assumed that the operation of the display device was not accidental or does not indicate an emergency. For example, a driver may briefly turn on the display device when greeting another driver. Therefore, if the operating time is shorter than the predetermined time, the transmission period will not be changed. Conversely, if the operating time is longer than the predetermined time, the transmission period will be changed to a shorter transmission period.

[0071] The above description discloses the following embodiments.

[0072] According to a first aspect of the present invention, there is provided a vehicle-to-vehicle communication device for a vehicle, comprising: a transmitting element for transmitting information about the vehicle to another vehicle at a predetermined period; a transmitting control unit for controlling the transmitting element; and a detector for detecting a state of a display device in the vehicle. The display device informs a person around the vehicle of a state and presence of the vehicle, and the transmitting control unit controls the transmitting element to transmit the information at a period shorter than the predetermined period when the detector detects that the display device is operating.

[0073] The indicator device serves to prevent an accident by issuing a warning to other vehicles in an emergency, for example. Alternatively, the indicator device can report a traveling direction and / or the presence of the vehicle to the other vehicles. Consequently, the indicator device informs the vehicles of the vehicle's condition and the vehicle's presence. Since the transmission control unit controls the transmission element to transmit the information in a period shorter than the predetermined period when the detector detects that the indicator device is operating, the other vehicles are immediately or quickly informed of the vehicle's presence.

[0074] Alternatively, the inter-vehicle communication device may further comprise a second detector for detecting a state of a braking device in the vehicle. The transmission control unit controls the transmission element to transmit the information in the period shorter than the predetermined period when the detector detects that the indicator device is operating and the second detector detects that the braking device is generating braking force. Since other vehicles are immediately notified of the presence of the vehicle, an accident such as a rear-end collision can be avoided.

[0075] Alternatively, the inter-vehicle communication device may further comprise a calculating device for calculating the period such that the period becomes shorter as the vehicle speed increases. The transmission control unit controls the transmission element to transmit the information in the calculated period when the detector detects that the display device is operating and the vehicle speed is above a predetermined speed. The method of shortening the transmission period as the vehicle speed increases is known from JP-A-2000-90395. Consequently, the above device has a wide range of applications because the known method can be applied to the inter-vehicle communication device. For example, the above method can be implemented using conventional software and / or a conventional method, so that the development cost can be reduced.Furthermore, the transmission control unit can control the transmitting element to transmit the information within the calculated period when the detector detects that the display device is no longer working. In this case, the wide range of applications of the device is greatly improved.

[0076] Alternatively, the vehicle-to-vehicle communication device may further comprise a calculating device for calculating the period such that the period becomes shorter as the vehicle speed increases. The transmission control unit controls the transmission element to transmit the information in the calculated period when the detector detects that the display device stops, starts, or stops working. In this case, the wide applicability of the device is greatly improved.

[0077] Alternatively, the vehicle-to-vehicle communication device may further include a calculating device for calculating the period such that the period becomes shorter as the speed of the vehicle increases. The transmission control unit controls the transmission element to transmit the information in the calculated period when the detector detects that the display device is operating, the second detector detects that the braking device is generating the braking force, and the speed of the vehicle is above a predetermined speed. Further, the transmission control unit may control the transmission element to transmit the information in the calculated period when the detector detects that the display device stops operating or the second detector detects that the braking device stops generating the braking force.

[0078] Alternatively, the inter-vehicle communication device may further include a calculating device for calculating the period such that the period becomes shorter as the speed of the vehicle increases. The transmission control unit controls the transmission element to transmit the information in the calculated period when the detector detects that the display device stops operating or the second detector detects that the braking device stops generating the braking force.

[0079] Alternatively, the indicator device may be a turn signal to indicate the vehicle's turning direction. Alternatively, the indicator device may be a hazard warning light to indicate a vehicle emergency.

[0080] Alternatively, the vehicle-to-vehicle communication device may further comprise: a first obtaining element for obtaining information about a first intersection to which the vehicle is approaching, the first intersection being the intersection closest to the vehicle in the direction of travel of the vehicle; a receiving element for receiving information about the other vehicle transmitted from the other vehicle; a second obtaining element for obtaining information about a second intersection to which the other vehicle is approaching, the second intersection being the intersection closest to the other vehicle in the direction of travel of the other vehicle; and a determining element for determining whether the second intersection coincides with the first intersection.The transmission control unit controls the transmission element to transmit the information in the period shorter than the predetermined period when the detector detects that the display device is operating and the determination element determines that the second intersection coincides with the first intersection.

[0081] Alternatively, the vehicle-to-vehicle communication device may further comprise: a first obtaining element for obtaining information about a first intersection to which the vehicle is approaching, the first intersection being the intersection closest to the vehicle in the direction of travel of the vehicle; a receiving element for receiving information about the other vehicle transmitted from the other vehicle; a second obtaining element for obtaining information about a second intersection to which the other vehicle is approaching, the second intersection being the intersection closest to the other vehicle in the direction of travel of the other vehicle; and a determining element for determining whether the second intersection coincides with the first intersection.The transmission control unit controls the transmission element to transmit the information in the period shorter than the predetermined period when the detector detects that the display device operates, the second detector detects that the braking device generates the braking force, and the determination element determines that the second intersection coincides with the first intersection.

[0082] According to a second aspect of the present invention, a method for communication between vehicles is provided, comprising the following steps: obtaining information about a vehicle; detecting a speed of the vehicle; calculating a transmission period as a first transmission period when the speed of the vehicle is less than or equal to a predetermined value; calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, wherein the second transmission period is shorter than the first transmission period; transmitting the information about the vehicle to another vehicle in the calculated transmission period; determining whether a hazard warning light is turned on; determining whether the speed of the vehicle is above the predetermined value; maintaining the calculated transmission period if the hazard warning light is not turned on or the vehicle speed is above the predetermined value;and changing the calculated transmission period to the second transmission period when the hazard warning light is turned on and the vehicle speed is less than or equal to the predetermined value;

[0083] According to the above procedure, the other vehicles are immediately informed of the presence of the vehicle.

[0084] According to a third aspect of the present invention, a method for communication between vehicles is provided, comprising the steps of: obtaining information about a vehicle; detecting a speed of the vehicle; calculating a transmission period as a first transmission period when the speed of the vehicle is less than or equal to a predetermined value; calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, the second transmission period being shorter than the first transmission period; transmitting the information about the vehicle to another vehicle in the calculated transmission period; determining whether a turn signal is turned on; determining whether a braking device is operating; determining whether the speed of the vehicle is above the predetermined value;Maintaining the calculated transmission period when the turn signal is not turned on, the braking device is not operating, or the vehicle speed is above the predetermined value; and changing the calculated transmission period to the second transmission period when the turn signal is turned on, the braking device is operating, and the vehicle speed is less than or equal to the predetermined value.

[0085] According to the above procedure, the other vehicles are immediately informed of the presence of the vehicle.

[0086] Although the present invention has been described in connection with various embodiments thereof, it should be understood that it is not limited to the above-described embodiments and construction. Various modifications and equivalent arrangements are intended to be included within the scope of the present invention. Furthermore, in addition to the combinations and configurations described above, other combinations and configurations including more, less, or only a single element are also intended to be included within the scope of the present invention.

[0087] Above, a vehicle-to-vehicle communication device for communication between vehicles and a method for communication between vehicles have been disclosed.

[0088] A vehicle-to-vehicle communication device for a vehicle includes: a transmitting element 22 for transmitting information about the vehicle to another vehicle at a predetermined period; a transmitting control unit 16, 18 for controlling the transmitting element 22; and a detector 24 for detecting a state of a display device 5a in the vehicle. The display device 5a informs a person around the vehicle of a state and presence of the vehicle, and the transmitting control unit 16, 18 controls the transmitting element 22 to transmit the information at a period shorter than the predetermined period when the detector 24 detects that the display device 5a is operating.

Claims

[1] A vehicle-to-vehicle communication device for a vehicle, the device comprising: - a transmitting element (22) for transmitting information about the vehicle to another vehicle in a predetermined transmission period; - a transmission control unit (16, 18) for controlling the transmission element; - a vehicle speed obtaining element for obtaining a speed of the vehicle; - a computing device (14, 16) for calculating the transmission period such that the transmission period becomes shorter as the speed of the vehicle increases; - a detector (24) for detecting a state of a display device (5a) in the vehicle; and - a speed determining element for determining whether the speed of the vehicle is greater than a predetermined speed, wherein - the display device (5a) informs a person around the vehicle about a condition and presence of the vehicle, and - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in a period shorter than the predetermined period calculated by the calculation device (14, 16) according to the speed of the vehicle when the detector (24) detects that the display device (5a) is operating and the speed determination element determines that the speed of the vehicle is not greater than the predetermined speed. [2] Vehicle-to-vehicle communication device according to claim 1, characterized by that it also has: - a second detector (24) for detecting a state of a braking device (4a) in the vehicle, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the period shorter than the predetermined period when the detector (24) detects that the display device (5a) is operating and the second detector (24) detects that the braking device (4a) is generating a braking force. [3] Vehicle-to-vehicle communication device according to claim 1 or 2, characterized by that it also has: - a calculating device (14, 16) for calculating the period such that the period becomes shorter as the speed of the vehicle increases, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) is operating and the speed of the vehicle is above a predetermined speed. [4] Vehicle-to-vehicle communication device according to claim 3, characterized by that the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) stops working. [5] Vehicle-to-vehicle communication device according to claim 1, characterized by that it also has: - a calculating device (14, 16) for calculating the period such that the period becomes shorter as the speed of the vehicle increases, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) stops operating. [6] Vehicle-to-vehicle communication device according to claim 2, characterized by that it also has: - a calculating device (14, 16) for calculating the period such that the period becomes shorter as the speed of the vehicle increases, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) is operating, the second detector (24) detects that the braking device (4a) is generating the braking force and the speed of the vehicle is above a predetermined speed. [7] Vehicle-to-vehicle communication device according to claim 6, characterized by that the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) stops working, or the second detector (24) detects that the braking device (4a) stops generating the braking force. [8] Vehicle-to-vehicle communication device according to claim 2, characterized by that it also has: - a calculating device (14, 16) for calculating the period such that the period becomes shorter as the speed of the vehicle increases, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the calculated period when the detector (24) detects that the display device (5a) stops working or the second detector (24) detects that the braking device (4a) stops generating the braking force. [9] Vehicle-to-vehicle communication device according to one of claims 1-8, characterized by that the display device (5a) is an indicator (5a) for indicating a turning direction of the vehicle. [10] Vehicle-to-vehicle communication device according to one of claims 1-8, characterized bythat the display device (5a) is a hazard warning light (5a) for indicating an emergency of the vehicle. [11] Vehicle-to-vehicle communication device according to one of claims 1-10, characterized by that it also has: - a first acquisition element (2, 24) for obtaining information about a first intersection which the vehicle is approaching, the first intersection being the intersection closest to the vehicle in the direction of travel of the vehicle; - a receiving element (24, 26) for receiving information about the further vehicle transmitted by the further vehicle; - a second acquisition element (24, 26) for obtaining information about a second intersection approaching the further vehicle, the second intersection being the intersection closest to the further vehicle in the direction of travel of the further vehicle; and - a determining element (18) for determining whether the second intersection coincides with the first intersection, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the period shorter than the predetermined period when the detector (24) detects that the display device (5a) is operating and the determination element (18) determines that the second intersection coincides with the first intersection. [12] Vehicle-to-vehicle communication device according to one of claims 2 and 6-8, characterized by that it also has: - a first acquisition element (2, 24) for obtaining information about a first intersection which the vehicle is approaching, the first intersection being the intersection closest to the vehicle in the direction of travel of the vehicle; - a receiving element (24, 26) for receiving information about the further vehicle transmitted by the further vehicle; - a second acquisition element (24, 26) for obtaining information about a second intersection approaching the further vehicle, the second intersection being the intersection closest to the further vehicle in the direction of travel of the further vehicle; and - a determining element (18) for determining whether the second intersection coincides with the first intersection, wherein - the transmission control unit (16, 18) controls the transmission element (22) to transmit the information in the period shorter than the predetermined period when the detector (24) detects that the display device (5a) is operating, the second detector (24) detects that the braking device (4a) is generating the braking force, and the determination element (18) determines that the second intersection coincides with the first intersection. [13] A method for communication between vehicles, comprising the following steps: - Obtaining information about a vehicle; - Detecting the speed of the vehicle; - Calculating a transmission period as the first transmission period when the speed of the vehicle is less than or equal to a predetermined value; - calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, the second transmission period being shorter than the first transmission period; - Sending the information about the vehicle to another vehicle during the calculated transmission period; - Determining whether a hazard warning light (5a) is switched on; - Determine whether the speed of the vehicle is above the predetermined value; - maintaining the calculated transmission period if the hazard warning light (5a) is not switched on or the vehicle speed is above the predetermined value; and - Changing the calculated transmission period to the second transmission period when the hazard warning light (5a) is switched on and the vehicle speed is less than or equal to the predetermined value. [14] A method for communication between vehicles, comprising the following steps: - Obtaining information about a vehicle; - Detecting the speed of the vehicle; - Calculating a transmission period as the first transmission period when the speed of the vehicle is less than or equal to a predetermined value; - calculating the transmission period as a second transmission period when the speed of the vehicle is above the predetermined value, the second transmission period being shorter than the first transmission period; - Sending the information about the vehicle to another vehicle during the calculated transmission period; - determining whether an indicator (5a) is switched on; - determining whether a braking device (4a) is operating; - Determine whether the speed of the vehicle is above the predetermined value; - maintaining the calculated transmission period when the indicator (5a) is not switched on, the braking device (4a) is not operating or the vehicle speed is above the predetermined value; and - Changing the calculated transmission period to the second transmission period when the turn signal (5a) is switched on, the braking device (4a) is operating and the vehicle speed is less than or equal to the predetermined value.

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