Abstract:
An apparatus provides information for a driver and passengers in a vehicle. If it is estimated that driving load is high, the apparatus stops outputting information. If it is estimated that driving load has been changed from high to low, the apparatus reads information from a storage unit and outputs the read information. If it is estimated that driving load is high, the apparatus stops outputting information so that the driver and passengers may miss no information, and if it is estimated that driving load is low, the apparatus provides information for the driver and passengers so that they may surely catch the information.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for providing various information pieces for persons in a vehicle. 
     An apparatus for providing information from newspapers, magazines, radios, televisions, etc., by voice for persons in a vehicle is disclosed in, for example, Japanese Unexamined Patent Publication No. 09-329458. To improve the understanding of a vehicle driver of voice information, this disclosure controls reading speed and punctuation pauses in response to driving load. When the vehicle passes another vehicle or when the vehicle crosses an intersection, the disclosure slows reading speed or elongates punctuation pauses so that the driver may easily catch voice information. 
     If the driving load on the driver further increases, slowing reading speed or elongating punctuation pauses is insufficient to allow the driver to properly catch voice information. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an apparatus for providing information for a driver and passengers in a vehicle, capable of surely transmitting information to the driver and passengers. 
     In order to accomplish the object, a first aspect of the present invention provides an apparatus for providing information for a driver and passengers in a vehicle, having an information source ( 14 ,  15 ,  16 ) for providing information, a storage unit ( 17 ) for storing the information, an output unit ( 12 ,  13 ) for outputting information read from the storage unit for the driver and passengers, a load estimation unit ( 11 ) for estimating driving load on the driver, and a controller ( 11 ) for controlling, according to the estimated driving load, the storage unit and output unit to read information from the storage unit and output the read information for the driver and passengers through the output unit. If the estimated driving load is high, the controller stops reading and outputting information. If the estimated driving load indicates a high-to-low load change, the controller starts reading and outputting information. 
     A second aspect of the present invention provides a method of providing information for a driver and passengers in a vehicle. The method includes acquiring information from an information source ( 14 ,  15 ), storing the information in a storage unit ( 17 ), outputting information read from the storage unit for the driver and passengers, estimating driving load on the driver, and controlling the information reading and outputting according to the estimated driving load to stop the information reading and outputting if the estimated driving load is high, and if the estimated driving load indicates a high-to-low load change, start the information reading and outputting by going back a predetermined period from the last stoppage of information reading and outputting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 generally shows the structure of an apparatus for providing information for persons in a vehicle according to a first embodiment of the present invention; 
     FIG. 2 is a flowchart showing a method of providing information for persons in a vehicle according to a second embodiment of the present invention executable with the apparatus of FIG. 1; and 
     FIGS. 3 and 4 are flowcharts showing the details of a driving load detecting step S 3  of FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows an apparatus for providing information for persons in a vehicle according to the first embodiment of the present invention. The apparatus includes a longitudinal acceleration sensor  1  for detecting an acceleration in the traveling direction of the vehicle and a transversal acceleration sensor  2  for detecting an acceleration in a direction transversal to the traveling direction. A speed sensor  3  detects the traveling speed of the vehicle, and a steering angle sensor  4  detects an angle of the steering wheel of the vehicle. A location detector  5  determines the present location of the vehicle with a satellite navigation system employing aGPS receiver (not shown), a self-contained navigation system employing a mileage sensor (not shown) and direction sensor (not shown), or a beacon system employing roadside beacons (not shown). A map memory  6  stores a road map. A gear position detector  7  detects the position of a shift lever. A stop switch  8  is used to manually stop information output. A resume switch  9  is used to resume information output. An ignition switch  10  is activated when an ignition key of the vehicle is turned on. 
     The apparatus of FIG. 1 also includes a controller  11  having a CPU  11   a , a ROM  11   b , a RAM  11   c , etc. The controller  11  executes a control program stored in the ROM  11   b , to control information to be provided for the persons in the vehicle. A display  12  displays video information, and a speaker  13  provides voice information. A receiver  14  receives voice and video information from radio stations, television stations, FM broadcasting stations, roadside beacons, etc. A player  15  plays back voice and video information from, for example, a CD, MD, DVD, and cassette tape. A telephone set  16  is, for example, a car-phone or cellular phone used to get weather forecast, time, telephone directory, and other voice and video information from, for example, the Internet. 
     A memory  17  temporarily stores audio and video information from various information sources while load on the driver is high. The memory  17  may be any type of memory such as a semiconductor memory and a disk unit. The capacity of the memory  17  is set to be sufficient to store audio and video information obtained from information sources during a period in which load on the driver is high. If information exceeding the capacity of the memory  17  flows in, older information pieces are abandoned from the memory  17 , so that the memory  17  may always be filled with newest information pieces. If required, the memory  17  keeps specific information pieces without abandoning them. It is preferable that the memory  17  stores information pieces from information sources without regard to the level of load on the driver. 
     In this specification, the “information” includes every type of audio and video information provided for a driver and passengers in a vehicle and the “information sources” include any devices that generate such information. The information includes audio and video information from information sources such as radio stations, television stations, FM broadcasting stations, roadside beacons, cellular phones, car-phones, the Internet, and vehicle-mounted devices such as MD, CD, DVD, and cassette-tape units. 
     FIG. 2 is a flowchart showing a method of providing information for persons in a vehicle according to the second embodiment of the present invention executable with the apparatus of FIG.  1 . The method is realized in the form of a program executed by the CPU  11   a  in the controller  11  of FIG. 1 at predetermined intervals after the ignition switch  10  is turned on. In step  1 , a person in the vehicle selects one of the receiver  14 , player  15 , telephone  16 , and the selected device provides audio and video information. This information is stored in the memory  17  in step  2 . 
     Step  3  carries out a driving load detecting routine whose details are shown in FIGS. 3 and 4. Step  4  determines whether or not the driving load detected in step  3  is high. High load and low load will be explained in detail later. If the detected driving load is high, step  5  is carried out, and if it is low, step  8  is carried out. If the detected driving load is high, step  5  classifies the driving load and stores the classified load. Step  6  checks to see if a person in the vehicle has activated the resume switch  9 . If the resume switch  9  is inactive, step  7  is carried out to provide no video or audio information from the display  12  and speaker  13 . 
     Namely, if the driving load on the driver of the vehicle is high, no information is provided, so that the driver has no chance of missing information. If the driving load is low, the driver can surely receive information. 
     If the driving load is high and if the resume switch  9  is active, it is determined that the driver is strongly intending to receive information. Then, step  13  reads video and audio information from the memory  17  and provides the persons in the vehicle with the read video and audio information through the display  12  and speaker  13 . To resume information output after an information output stoppage, information in the memory  17  is read from the information output stoppage point and the read information is provided for the persons in the vehicle through the display  12  and speaker  13 . 
     It is possible to resume information output by going back a predetermined period of, for example, 30 seconds from the information output stoppage point, to overlap the information provided last time and this time for the predetermined period of 30 seconds. This secures information continuity and allows the persons in the vehicle to easily understand the content of the information. 
     If the step  4  determines that the driving load is not high, step  8  checks to see if the stop switch  8  is active. If the stop switch  8  is active, the step  7  is carried out to output no video or audio information from the display  12  and speaker  13 . If the stop switch  8  is inactive, step  9  checks to see if the driving load is low. If the step  4  determines that the driving load is not high, i.e., low, and if the step  9  determines that the driving load is not low, it is determined that an abnormality has occurred, and the program is terminated. When it is determined that the driving load is low, one embodiment may directly provide information from the information sources  14  to  16  for the persons in the vehicle in real time with the use of the display  12  and speaker  13 . 
     Step  10  checks to see if the preceding load is high and the present load is low. Namely, step  10  determines whether or not the driving load indicates a high-to-low load change. If there is no high-to-low load change, step  13  is carried out to output information as mentioned above. If the driving load indicates a high-to-low load change, step  11  is carried out to determine whether or not the preceding high load is special high load. 
     The special high load occurs when a longitudinal or transversal acceleration of the vehicle is above a predetermined value. For example, a rapid deceleration will be observed when avoiding a collision, and a rapid acceleration will be observed when passing another vehicle. To handle these cases as special, a longitudinal acceleration of, for example, 0.3 G or over is classified as the special high load. Similarly, rapid steering will be observed when avoiding a collision. To handle such a case as special, a transversal acceleration of, for example, 0.3 G or over is classified as the special high load. 
     Under such special high load, psychological burden on the driver steeply increases. To restore a normal psychological state from such high psychological burden, the driver needs a certain time after the special high load returns to a normal load level. Accordingly, instead of quickly starting information output as soon as the special high load returns to a normal load level, the present invention delays information output by a predetermined time, for example, three minutes from the time when the special high load returns to a normal load level, so that the driver may surely catch information. 
     If the preceding driving load is high but not the special high load, the driver will speedily restore a normal psychological state. In this case, information output can be resumed as soon as the driving load changes from high to low. 
     If the step  11  determines that the preceding high driving load is the special high load, step  12  starts information output after the predetermined time. Namely, information is read from the memory  17  after the predetermined time, and the read information is provided for the persons in the vehicle through the display  12  and speaker  13 . When resuming information output, it may be resumed from a last information output stoppage point, or it may be resumed by going back a given time period from the last information output stoppage point. If requested, latest information may be output without regard to the last information output stoppage point. 
     When resuming information output, the controller  11  may thin information depending on the content of the information, to provide only an outline of the information for the persons in the vehicle. This reduces the amount of information to be reproduced for an information output stoppage period, thereby shortening a playback time for the information output stoppage period. Instead, the controller  11  may increase a playback speed of the information within the information output stoppage period, to shorten a playback time. With these techniques, the present invention shortens a playback time of the information in the information output stoppage period, to catch up live information to be provided from the information sources in real time. 
     The details of the driving load detecting step  3  of FIG. 2 will be explained with reference to FIGS. 3 and 4. Step  21  checks to see if a vehicle speed detected by the speed sensor  3  is zero. Namely, the step  21  checks to see if the vehicle is stopped. If the vehicle is stopped, step  22  determines that the driving load is low, and the flow returns to the step  4  of FIG.  2 . 
     If the vehicle speed is not zero, step  23  checks to see if a longitudinal acceleration detected by the longitudinal acceleration sensor  1  is above a predetermined value. If it is above the predetermined value, step  24  determines that the driving load is the special high load, and the flow returns to the step  4  of FIG.  2 . If the longitudinal acceleration is below the predetermined value, step  25  checks to see if a transversal acceleration detected by the transversal acceleration sensor  2  is above a predetermined value. If it is above the predetermined value, the step  24  determines that the driving load is the special high load, and the flow returns to the step  4  of FIG.  2 . 
     Step  26  refers to a present vehicle location detected by the location detector  5  and the road map stored in the map memory  6  and checks to see if the vehicle is running around an intersection. If the vehicle location is within, for example, 50 m from the center of an intersection, it is determined that the vehicle is driving around the intersection. In this case, step  27  determines that the driving load is high because the driver must pay intensive attention to driving around the intersection. Then, the flow returns to the step  4  of FIG.  2 . 
     Step  28  refers to the vehicle location detected by the location detector  5  and the road map stored in the map memory  6  and determines whether or not the vehicle is driving along a narrow road. The narrow road is defined as, for example, a minor road below a city road, or a road narrower than 3 m in width. If the vehicle is driving along a narrow road, the step  27  determines that the driving load is high because the driver must pay an intensive attention to driving along the narrow road. Then, the flow returns to the step  4  of FIG.  2 . 
     Step  29  refers to driving history based on the location detector  5  and determines whether or not the present road is a first or inexperienced road for the vehicle. For example, the controller  11  stores a route driven by the vehicle for the last two weeks, or a route of 100 km run by the vehicle. Any route that differs from the stored route is determined as a first one. If the vehicle is running along a first or inexperienced road, the step  27  determines that the driving load is high because the driver must pay more attention to driving the inexperienced road. Then, the flow returns to the step  4  of FIG.  2 . 
     If the driver has some areas in his or her mind to pay special attention to driving through the areas, the driver may set the areas in the controller  11  in advance. In this case, the flow of FIG. 3 includes an additional step of determining whether or not the vehicle is driving through one of such areas. If the step determines that the vehicle is driving through one of such areas, the step determines that the driving load is high and returns to the step  4  of FIG.  2 . 
     Step  30  refers to the vehicle location detected by the location detector  5  and the road map in the map memory  6  and determines whether or not the vehicle is running around a tollgate. If the vehicle is within, for example, 10 m from a tollgate, the step  30  determines that the vehicle is driving around the tollgate. In this case, step  31  checks to see if the vehicle speed detected by the speed sensor  3  is below, for example, 10 km/h. If the vehicle is running at a low speed around the tollgate, it is presumed that a toll is going to be paid and that special attention is needed not only to drive the vehicle but also to pay the toll. Therefore, the step  27  determines that the driving load is high and returns to the step  4  of FIG.  2 . 
     Step  32  checks to see if a gear position detected by the gear position detector  7  is a back position. Namely, the step  32  checks to see if the vehicle is driving backward. If the vehicle is backing, the step  27  determines that the driving load is high and returns to the step  4  of FIG.  2 . An encoder may be attached to a shaft or a wheel, to generate a pulse signal representing a rotational angle of the shaft or wheel based on which a backward movement of the vehicle is detectable. 
     Step  35  of FIG. 4 refers to the vehicle location detected by the location detector  5  and the road map in the map memory  6  and checks to see if the vehicle is running around a destination. If the vehicle is running around the destination, step  37  checks to see if the vehicle speed is below 10 km/h. If the vehicle is running around the destination at a low speed, step  38  checks to see if the vehicle is driving around a predetermined parking lot. If the vehicle is driving around the parking lot, step  39  checks to see if the vehicle is moving backward. If the vehicle is backing in the parking lot, step  40  determines that the driving load is high and returns to the step  4  of FIG.  2 . If the vehicle is not backing, step  41  checks to see if the vehicle is moving back and forth more than predetermined times. If the vehicle is frequently moving back and forth, the step  40  determines that the driving load is high and returns to the step  4  of FIG.  2 . If the frequency of the back-and-forth movement of the vehicle is less than the predetermined value, step  42  determines that the driving load is low and returns to the step  4  of FIG.  2 . 
     According to one embodiment, a traveling direction of the vehicle may be determined from temporal changes in vehicle location, to determine whether or not the vehicle is moving toward or away from a destination, to help make correct determination in the steps  35  to  38 . 
     If the step  35  determines that the vehicle is not in the vicinity of the destination, or if the step  37  determines that the vehicle is running around the destination at a high speed, or if the step  38  determines that the vehicle is running around the destination but not around the parking lot, step  36  determines that the driving load is low and returns to the step  4  of FIG.  2 . 
     In this way, if the driving load is high, the present invention provides no information for the persons in the vehicle through the display  12  and speaker  13 . If the driving load indicates a high-to-low load change, the present invention starts reading information from the memory  17  and providing the read information for the persons in the vehicle through the display  12  and speaker  13 . The present invention provides no information for the driver if the driving load on the driver is high, so that the driver may miss no information. When the driving load is low, the present invention provides the driver with information, so that the driver may surely catch the information. 
     Information types and information sources handled by the present invention are not limited to those explained with reference to the embodiments. Other information types and information sources are also applicable to the present invention. The high and low driving load conditions mentioned in the embodiments must not be considered to limit the present invention. According to the present invention, any driving condition that requires a driver to concentrate on the driving of a vehicle may be defined as a high driving load condition, and other driving conditions may be defined as low driving load conditions. 
     The entire content of a Japanese Patent Applications No. 2000-278135, filed on Sep. 13, 2000 is hereby incorporated by reference. The scope of the invention is defined with reference to the following claims.