Abstract:
A vehicle recommendation speed display system includes a vehicle speed sensor, a recommendation speed processing unit that calculates a recommended speed based on a vehicle speed and a display unit that is usually mounted in a speedometer. The recommendation speed processing unit is configured to send information on the vehicle recommended speed to the display unit to display the recommended speed regardless of whether an actual vehicle speed is higher than the recommended speed or not in order to prevent a driver from being irritated by a difference between the actual vehicle speed and a vehicle speed intended by the driver.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority from Japanese Patent Application 2006-131601, filed May 10, 2006, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an on-vehicle system that displays a recommendation speed of a vehicle. 
     2. Description of the Related Art 
     JP-2004-142686A discloses a vehicle cruise control system that controls the cruising speed of a vehicle. This cruising control system determines a target speed based on the distance of a preceding vehicle from the own vehicle and road information ahead of the own vehicle and reduces the vehicle speed if the vehicle speed is higher than the target speed. 
     JP-2004-210053A discloses a vehicle cruise control system that controls the cruising speed of a vehicle based on road information about curves of a road and the speed of the vehicle. This cruising control system delays the timing of reducing control of the vehicle speed when there is a preceding vehicle. 
     However, because the driver is not informed of the target speed by the above cruise control systems, the driver may feel irritated when the driver&#39;s intention of the vehicle operation is different from the vehicle speed. 
     JP-2004-0287856A discloses a display means for displaying a message if the vehicle speed becomes higher than a regulation speed. However, no information is given to the driver when the vehicle speed is controlled based on various other conditions. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the invention is to provide a vehicle recommendation speed displaying system that can prevent the driver from irritating due to a difference between the intention of the driver and the actual vehicle operation that is controlled by a vehicle speed control system. 
     According to a main feature of the invention, a recommendation speed display system for a vehicle includes a vehicle speed sensor, a recommendation speed processing unit for providing a vehicle recommendation speed based on a vehicle speed and a display unit. The recommendation speed processing unit is configured to send information on the vehicle recommendation speed to the display unit to display the information regardless of whether an actual vehicle speed is higher than the recommendation speed or not. 
     The recommendation speed display system according to the main feature of the invention may further include one of the following means: means for sensing vehicle conditions so as to provide a vehicle recommendation speed based on one of the vehicle conditions in addition to the vehicle speed; means for monitoring a driver in driving the vehicle; and means for sensing road conditions relating to the vehicle. 
     In the above cases, the recommendation speed processing unit can provide a vehicle recommendation speed based on a countenance or behavior of the driver in addition to the vehicle speed or information sensed by the means for sensing road conditions in addition to the vehicle speed. In this case, the recommendation speed processing unit may include a neighboring circumstance recognition section, a driver condition recognition section, a vehicle condition recognition section and means for calculating the recommendation speed, and the means for sensing road conditions may include at least one of a laser radar, a road-to-vehicle communication unit and a navigation system. 
     The recommendation speed display system according to the main feature of the invention may further include a display data formation section for forming a display image based on the recommendation speed. 
     In the recommendation speed display system according to the main feature of the invention, the recommendation speed processing unit may be configured to provide the recommendation speed that is selected from a plurality of candidates of the recommendation speed that are based on a plurality of kinds of information relating to the vehicle. In this case, the recommendation speed processing unit may be configured to send the information to the display unit to display a basis of providing the recommendation speed in addition to the vehicle recommendation speed. 
     In the recommendation speed display system according to the main feature of the invention, the display unit may be disposed in the speedometer. 
     The recommendation speed display system according to the main feature of the invention may further include an operating panel by which a set speed is set by the driver and means for controlling speed of the vehicle within a control speed so that the recommendation speed processing unit can provide the control speed based on the set speed of the operating panel set by the driver. 
     In this recommendation speed display system: the recommendation speed processing unit may include a control speed calculation section that is configured to send information on the control speed to the display unit to display the control speed; or may provide a subordinate mode in which the vehicle speed is controlled based on a control speed that changes according to the recommendation speed displayed by the display unit. The above control speed calculation section may be configured to further provide a limited period mode in which the vehicle speed is controlled based on a set speed in a limited period until the display recommendation speed of the recommendation speed changes. 
     In the above recommendation speed display system the display unit may be configured to display the vehicle recommendation speed by a spot light at a portion that corresponds to a speed scale of the speedometer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings: 
         FIG. 1  is a block diagram illustrating a vehicle control system that includes a recommendation speed display system according to a preferred embodiment of the invention; 
         FIGS. 2A-2G  illustrate a speedometer in which a display member of the recommendation speed display system is mounted to display various kinds of information; 
         FIG. 3  is a flow diagram of processing data to be displayed; 
         FIG. 4  is a flow diagram of determining a control speed; 
         FIG. 5  is a flow diagram of outputting the control speed; 
         FIGS. 6A and 6B  illustrate a meter instrument that includes a liquid crystal display member of the recommendation speed display system; and 
         FIG. 7  illustrates a display of the recommendation speed display system projected on a windshield glass. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A recommendation speed display system according to a preferred embodiment according to the present invention will be described with reference to the appended drawings. 
     A vehicle control system that includes the recommendation speed display system will be described with reference to  FIG. 1 . The vehicle control system is mounted in a vehicle and constructed of a recommendation speed processing unit  10 , an operating panel  21 , a display unit  22 , a laser radar  23 , a millimeter wave radar  23 ′, a road-to-vehicle communication unit  24 , a vehicle-to-vehicle communication unit  24 ′, a navigation system  25 , a camera  26 , a vehicle monitoring system  27 , a vehicle speed sensor  31 , a vehicle speed control value calculation section (hereinafter referred to as speed calculation section)  32 , a vehicle motion control section  33 , a power train  34 , a brake system  35 , etc. 
     The operating panel  21  is provided with plural push buttons for inputting command signals that include the signal of a set speed. Incidentally, the operating panel may be provided with a voice recognition device instead of the push buttons. 
     The display unit  22  is mounted in a speedometer, as shown in  FIGS. 2A-2G  The display unit  22  is constructed of a character display section disposed at a central portion of the speedometer and a speed indicating section disposed along the periphery of the speedometer. 
     The character display section is constructed of a liquid crystal display member that displays a message provided by the recommendation speed processing unit  10  by red or blue characters. The speed indicating section is constructed of plural LED&#39;s disposed along the periphery of the speedometer so that red (R), blue (B) or green (G) spot light can be turned on at portions that correspond to the scales of the speedometer to indicate a maximum speed, a recommendation speed or a control speed according to a signal provided by the recommendation speed processing unit  10 . Incidentally, the display unit  22  may be mounted on a portion of a meter panel, as shown in  FIGS. 6A and 6B . The display unit may be mounted in a head up display to display information on a portion of the windshield grass in front of the driver seat, as shown in  FIG. 7 . 
     The laser radar  23  is located at the front of the vehicle. The laser radar  23  includes a transmitting section that scans laser light having the directivity right and left and a receiving section that receives reflected light of the laser light. The laser radar  23  detects an object coming up ahead of the vehicle based on the scanned laser light and the reflected laser right, measures the distance between the vehicle and the object and sends its output signal to the recommendation speed processing unit  10 . 
     The radar  23 ′ is also located at the front of the vehicle. The radar  23 ′ includes a transmitting section that emits radio wave and a receiving section that receives reflected wave of the radio wave. The radar  23 ′ detects an object coming up ahead of the vehicle based on the radio wave and the reflected wave of the radio wave, measures the distance and a relative speed between the vehicle and the object, and sends its output signal to the recommendation speed processing unit  10 . 
     The road-to-vehicle communication unit  24  receives various kinds of information, such as information on the highway regulation from an on-road communication facility by means of short-distance wireless communication and sends the data to the recommendation speed processing unit  10 . 
     The vehicle-to-vehicle communication unit  24 ′ receives data on the vehicle speed, vehicle location, vehicle conditions, braking, etc. from an on-vehicle communication device of a neighboring vehicle by means of short-distance wireless communication and sends the data to the recommendation speed processing unit  10 . 
     The navigation system  25  outputs various kinds of information such as the speed limit, traffic jam, blockage of road due to construction or a traffic accident, school zone, residential area, own vehicle location, etc. to the recommendation speed processing unit  10 . 
     The camera  26  periodically monitors the vehicle driver&#39;s face or countenance and outputs a monitored image to the recommendation speed processing unit  10 . 
     The monitoring system  27  detects a trouble or an abnormality of the following systems or devices: ESC (electronic stability control) system, ABS (antilock brake control) system, a suspension control system, an electronic four-wheel-driving control system, an electronic differential gear control system, a catalyzer, tire&#39;s air pressure, etc. The monitoring system  27  also reports such a trouble or an abnormality to the recommendation speed processing unit  10 . 
     The recommendation speed processing unit  10  provides a control speed based on a signal received from the operating panel  21 , sends a control speed signal to the speed calculation section  32  so as to control the vehicle speed within the control speed, as a set speed, and provide a recommendation speed that is optimum under circumstances on the display unit. 
     The vehicle speed sensor  31  detects the vehicle speed (or running speed of the vehicle). The speed calculation section  32  calculates a control value to control the actual vehicle speed and sends the control value to the vehicle motion control section  33 . 
     The vehicle motion control section  33  controls the power train  34  and the brake  35  based on the control value and the operation of the accelerator pedal and the brake pedal, thereby controlling the vehicle speed within the control speed. 
     The recommendation speed processing unit  10  is mainly constructed of a microcomputer that includes CPU, ROM, RAM, I/O and bus lines. As shown in  FIG. 1 , the recommendation speed processing unit  10  includes a neighboring circumstance recognition section  11 , a driver condition recognition section  12 , a vehicle condition recognition section  13 , a first recommendation speed calculation section  14 , a second recommendation speed calculation section  15 , a control speed calculation section  16  and a display data formation section  17 , which may be separated or joined to each other. 
     The neighboring circumstance recognition section  11  recognizes neighboring circumstances based on the data received from the laser radar  23 , the road-to-vehicle communication unit  24  and the navigation system  25  and sends a circumstance recognition signal to the first recommendation speed calculation section  14 . The driver condition recognition section  12  recognizes the driver&#39;s face or countenance based on the monitored image received from the camera  26  and sends a driver condition recognition signal to the first recommendation speed calculation section  14 . The vehicle condition recognition section  13  recognizes a trouble or abnormality of the vehicle based on the data received from the vehicle monitoring system  27  and sends an abnormality recognition signal to the second recommendation speed calculation section  15 . The first recommendation speed calculation section  14  calculates plural candidates of recommendation speeds based on the data received from the neighboring circumstance recognition section  11  and driver condition recognition section  12  and outputs the lowest one of the candidates as the recommendation speed to the display data formation section  17 . The control speed calculation section  16  calculates a control speed based on the signal received from the operating panel  21  and sends a control speed signal to the display data formation section  17  and the speed calculation section  32 . The display data formation section  17  forms a display image based on a first recommendation speed signal received from the first recommendation speed calculation section  14 , a second recommendation speed signal received from the second recommendation speed calculation section  15  and a control speed signal received from the control speed calculation section  16  and sends a display image signal to the display unit  22 . 
     The operation of the recommendation speed processing unit  10  will be described with reference to  FIGS. 3-5 . 
     At first, a display information outputting process will be described with reference to  FIG. 3 . In this process, the first recommendation speed calculation section  14  periodically (e.g. each 100 ms) calculates the first candidates of the recommendation speed based on the data received from the neighboring circumstance recognition section  11  and driver condition recognition section  12 , at step S 101 . In more detail, whether there is any preceding vehicle running ahead of the own vehicle is examined based on the output signal of the laser radar  23 , and a candidate of the recommendation speed is set based on a preceding vehicle&#39;s speed if there is such a preceding vehicle. Otherwise, the recommendation speed is not set. 
     Next, if information about a speed limit (caused by side wind, icy road, or fog) is received from the road-to-vehicle communication unit  24 , the speed limit is set as a candidate of the recommendation speed. Otherwise, the recommendation speed is not set. 
     If a speed limit information is detected by the navigation system  25  thereafter, the detected speed limit is set as a candidate of the recommendation speed. Otherwise, the recommendation speed is not set. 
     If a traffic jam information is detected by the navigation system  25  thereafter, a preset speed for the traffic jam is set as a candidate of the recommendation speed. Otherwise, the recommendation speed is not set. 
     Then, the sleepiness of the driver is examined based on the data signal received from the camera  26 . If it is determined that the driver is sleepy, a preset speed for the sleepy driver is set as a candidate of the recommendation speed. Incidentally, the sleepiness can be judged by the motion of the eyelids. The sleepiness can be also judged by driver&#39;s pulsation. In this case, the camera is replaced with a pulse sensor. Instead of sleepiness, driver condition may be examined. 
     If two or more candidates of the recommendation speed are set, the lowest candidates of the recommendation speed is finally set as the first recommendation speed. 
     Subsequently, the second recommendation speed is set based on the information about a trouble or an abnormality at S 102 . In more detail, whether a trouble or an abnormality of the own vehicle takes place or not is examined based on the information received from the vehicle monitoring system  27 . If there is a trouble or an abnormality, a preset speed for the trouble or abnormality is set as the second recommendation speed. Otherwise, it is not set. 
     Subsequently, a display recommendation speed is determined out of the first recommendation speed and the second recommendation speed at S 103 . If the first and second recommendation speeds are set, the lower one of the recommendation speeds is displayed as the display recommendation speed. If only one of the first and second recommendation is provided, the only one recommendation speed is displayed as the display recommendation speed. If none of the first and second recommendation speed is provided, a preset speed such as the legal speed limit is displayed as the display recommendation speed. 
     Thereafter, information about reasons of the display recommendation speed is formed at S 104  and displayed at S 105 . If, for example, a display recommendation speed is displayed based on a traffic jam, a blue-colored message “TRAFFIC JAM AHEAD” is formed to be displayed by the display unit  22  with a blue colored display of the display recommendation speed (the first recommendation speed), as shown in  FIG. 2D . If the ESC fails, a red-colored message “ESC FAILS” is formed to be displayed with a red-colored display of the display recommendation speed (the second recommendation speed), as shown in  FIG. 2A . The red colored message and red colored display recommendation speed represents higher importance than the blue colored message and display recommendation speed. 
     At S 105 , the display recommendation speed that is determined at S 103 , the information about reasons of the display recommendation speed and the control speed that is set at S 302  or S 305  are outputted to the display unit  22 , in which the display recommendation speed is displayed by a red or blue spot light and the control speed is displayed by a blue spot light. Then the display information outputting process is ended. 
     A control speed setting process for automatically controlling the vehicle speed will be described with reference to  FIG. 4 . 
     When the control speed setting process is started by the operating panel  21 , whether an operation by the operating panel  21  is to stop speed control or not is examined at S 201 . If the examination result is NO, whether the operation by the operating panel  21  is to start a subordinate mode or not is examined at S 202 . The subordinate mode is a mode to control the vehicle speed based on a control speed that changes according to the display recommendation speed displayed by the display unit. 
     If the result of the examination at the step S 202  is YES, the subordinate mode is started at S 203 , and the control speed setting process is ended thereafter. If the result of the examination at S 202  is NO, a limited period mode is started at S 204  and, thereafter, the control speed setting process is ended. The limited period mode is a mode to control the vehicle speed based on a set speed in a limited period until the display recommendation speed changes. 
     When the result of the examination at S  201  is YES, the speed control is stopped at S 205 , and the control speed setting process is ended. 
     A control speed outputting process for automatically controlling the vehicle speed will be described with reference to  FIG. 5 . 
     When the control speed outputting process is started, whether the mode is the subordinate mode or not is examined at S 301 . If this examination result is YES, the sum of the display recommendation speed determined at S 103  and an adjusting speed (plus or minus value) set when the subordinate mode is started is set as the control speed at S 302 . Thereafter, the step goes to S 306  to output the control speed. 
     If the result of the examination at S 301  is NO, whether the mode is the limited period mode or not is examined at S 303 . If this examination result is YES, whether the current display recommendation speed has changed from the display recommendation speed when the limited period mode is operated or not is examined at S 304 . If this examination result is NO, the speed set in the limited period mode is set to the control speed at S 305 . Thereafter, the control speed set at S 302  or S 305  is outputted to the speed calculation section  32  at S  306 , and the control speed outputting process is ended. On the other hand, if the result of the examination at S 303  is NO, the control speed outputting process is immediately ended. If it is judged that the display recommendation speed has changed at S 304 , the step goes to S 307  to end the vehicle speed control operation. Thereafter, the control speed outputting process is ended. 
     Thus, the recommendation speed display system according to the invention determines a recommendation speed that is optimum for a specific circumstance and displays the display recommendation speed regardless of whether an actual vehicle speed is higher than the display recommendation speed or not. Therefore, a driver can always grasp the display recommendation speed while he is driving the vehicle, so that the driver will not feel irritated by a difference between the intention of the driver and the vehicle operation. 
     In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention is to be regarded in an illustrative, rather than a restrictive, sense.