Patent Publication Number: US-2010129263-A1

Title: Method for Supporting A Driver Using Fragrance Emissions

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The disclosure of Japanese Application No. 2006-184770 filed on Jul. 4, 2006 including the specification, drawings, and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a driving support system that emits a fragrance inside a vehicle to promote, for a driver, the maintenance of an appropriate state for a driving environment. 
     2. Related Art 
     As a driving support apparatus for a vehicle, one has been developed, and has been put to practical use, that applies a technique involving the use of a vehicular mounted camera for detecting the driving environment to the front of a moving vehicle. This driving support apparatus performs tracing or warning control, based on the driving environment, relative to the space to the front of the moving vehicle, and generates a warning when an obstacle is detected in the path ahead. 
     Further, studies have also recently been performed to evaluate effects produced when various fragrances were introduced into the interior of a vehicle. 
     For example, in JP-A-06-255358, a technique is disclosed that involves the emission, by a fragrance apparatus, of various types of fragrances that effectively promote wakefulness, and to directionally alter and adjust forced air streams to propel these fragrances towards a driver in order to prevent the driver from dozing off at the wheel. 
     As disclosed in JP-A-06-255358, according to the conventional art, a fragrance intended to maintain driver&#39;s alertness is introduced into a vehicle, to keep a driver from dozing off while driving. However, even when the driver is alert, the state of the driver may differ. That is, in accordance with the conventional technique, emitting of a fragrance is not performed to change the state of a driver from one wherein the driver is concentrating only on one object to the front, such as a forward moving vehicle in the path ahead, to a state wherein the driver is concentrating not only on the vehicle to the front but is also acutely aware of all that is occurring in the immediate vicinity, and to maintain this altered state. 
     Therefore, it is difficult, according to the conventional art, for a driver state to be maintained that appropriately satisfies the requirements of the driving environment. 
     SUMMARY OF THE INVENTION 
     One or more embodiments of the invention provide a driving support system that emits a fragrance appropriate to the state of a driver, so that a driver state consonant with the driving environment can be maintained. 
     In accordance with one or more embodiments of the invention, a driving support system using fragrance emitting is provided with: 
     a fragrance generator, for emitting a fragrance inside a vehicle; 
     a driver state determination unit, for determining whether the state of a driver of the vehicle is a extremely-concentrating state, indicating the driver is concentrating only on one object to the front, or a random scanning state, indicating the driver is attentively aware of conditions in the immediate vicinity of the vehicle; and 
     a controller, for controlling, in accordance with the state of the driver, as determined by the driver determination unit, the emitting of the fragrance inside the vehicle to maintain the random scanning state or to shift the state of the driver from the extremely-concentrating state to the random scanning state. 
     According to one or more embodiments of the invention, the driving support system using fragrance emitting releases a fragrance in consonance with the state of a driver, to maintain a driver state that is appropriate to the driving environment. 
     Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing the basic configuration of a driving support system according to a first exemplary embodiment of the invention. 
         FIG. 2  is a diagram for explaining a variance in line-of-sight behavior for a front field of vision and a front, moving vehicle according to the first exemplary embodiment. 
         FIG. 3  is a diagram for explaining an example of attentiveness evaluation value according to the first exemplary embodiment. 
         FIG. 4  is a diagram for explaining fragrance emitting positions according to the first exemplary embodiment. 
         FIG. 5  is a flowchart for the driver state determination processing according to the first exemplary embodiment. 
         FIG. 6  is a flowchart for the fragrance emitting control processing according to the first exemplary embodiment. 
         FIGS. 7A to 7C  are explanatory diagrams showing examples fragrance emitting timing according to the first exemplary embodiment. 
         FIG. 8  is a flowchart for the driver state determination processing according to a second exemplary embodiment of the invention. 
         FIG. 9  is a flowchart for the fragrance emitting control processing according to the second exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the invention will now be described while referring to the drawings.  FIGS. 1 to 7  are related to a first exemplary embodiment of the invention. That is,  FIG. 1  is a diagram showing the basic configuration of a driving support system.  FIG. 2  is a diagram for explaining variances in the line-of-sight behavior in the forward range of vision and the width of a front, moving vehicle.  FIG. 3  is a diagram for explaining example of attentiveness evaluation values.  FIG. 4  is an explanatory diagram showing a fragrance emitting position.  FIG. 5  is a flowchart for the driver state determination processing.  FIG. 6  is a flowchart for fragrance emit control processing. And  FIGS. 7A to 7C  are charts for explaining example fragrance emit timings. 
     A driving support system  1  in  FIG. 1  emits a fragrance inside a vehicle, such as an automobile, and supports driving, so that the condition of a driver is appropriate to the driving environment. This driving support system  1  is mainly provided with: a driver state estimation device  10  for assuming the state of a driver; and a fragrance generation device  20  for emitting a fragrance that is emitted by a predetermined air freshener. 
     In the first exemplary embodiment, the driver state estimation device  10  estimates that a driver is either extremely-concentrating which indicates a driver is in a high degree of tension, or is randomly scanning which indicates the driver is adapting to the driving environment. Further, an attentiveness evaluation value Sh is employed as an evaluation value to determine whether the driver is either extremely-concentrating or randomly scanning. As will be explained later, the attentiveness evaluation value Sh is calculated based on the line-of-sight behavior of a driver, which is detected by a camera, and image recognition to the front, outside a vehicle, which are obtained by a camera or a laser radar. 
     Specifically, by detecting the line-of-sight behavior of the driver using the camera, the direction in which the driver is looking while driving can be identified, and when a relationship between an object to the front, outside the vehicle, which is detected by image recognition, and eye movement relative to this object is obtained, the state of a driver is determined to be either “extremely-concentrating”, indicating that the driver is tensely concentrating on an object to the front, or “randomly scanning”, indicating that while adapting to the driving environment the driver is not only watching an object to the front but is peripherally viewing, and is attentively aware of, conditions within the entire surrounding area, not just the object to the front. 
     Specifically, the driver state estimation device  10  includes: a visual field camera  11 , which captures the eye movements of a driver; an infrared lamp  12 ; a line-of-sight detection unit  13 , for detecting the line of sight of a driver using the visual field camera  11  and the infrared lamp  12 ; an external monitoring camera  14 , which captures, the scene outside and to the front a vehicle; an image recognition unit  15 , which processes a signal received from the external monitoring camera  14 ; and a driver state determination unit  16 , which determines the state of a driver based on the information for the line-of-sight behavior of the driver, detected by the line-of-sight detection unit  13 , and on the information obtained by the image recognition unit  15  for the scene outside and to the front of the vehicle. 
     In the first embodiment, a so-called pupillary/corneal reflex method is employed to detect the line-of-sight behavior of the driver, the visual field camera  11  is, for example, a camera that includes an infrared CCD, and the infrared lamp  12  is, for example, an LED lamp. Furthermore, in this embodiment, a stereo camera, which includes a pair of cameras arranged at a predetermined interval, is employed as the external monitoring camera  14 , and in order to obtain the situation outside the vehicle, stereo image processing is performed for an object (a three-dimensional object) outside the vehicle that is picked up by this stereo camera. 
     For the detection of the line-of-sight behavior by the line-of-sight detection unit  13 , due to differences in the rotation centers of a cornea and an eyeball, a virtual image formed by the infrared lamp  12  on a cornea is moved parallel in accordance with the movement of an eye, and the visual field camera  11  detects this parallel movement, using the center of a pupil as a reference, while detecting the center of the pupil at the same time. The detection method for the line-of-sight behavior is not limited to this method, and if available, another method may be employed, such as the EOG (Electro-Oculography), the scleral reflex method, the corneal reflex method or the search coil method. 
     For a pair of stereo images to the front of a possessing vehicle obtained by the external monitoring camera  14 , which is a stereo camera, the image recognition unit  15  obtains distance information using the principle of a triangular survey performed based on a difference in corresponding positions, and generates a distance image that represents a 3D distance distribution. 
     Then, based on data for the distance image, the image recognition unit  15  performs the known group processing, compares the resultant data with frames (windows) that are stored in advance, such as 3D road form data, side wall data and 3D object data, and extracts white line data, side wall data for guard rails and curbs existing along roads, and 3D object data for vehicles. 
     Different numbers are provided for these white line data, the side wall data and the 3D object data. In addition, in accordance with a relationship between a change in the distance from the possessing vehicle and the vehicular velocity of the possessing vehicle, the 3D object data is classified into a stationary object and a forward moving object that is moving substantially in the same direction as the possessing vehicle. 
     For example, of the forward moving objects that are sequentially detected in the travel region of the possessing vehicle over a predetermined period of time, the 3D object nearest the possessed object is registered as a front, moving vehicle. In the first exemplary embodiment, information for this front, moving vehicle is output to the driver state determination unit  16  as information for recognition outside the vehicle that is compared with the line-of-sight behavior of the driver. 
     The driver state determination unit  16  determines the state of a driver based on the information for the line-of-sight behavior detected by the line-of-sight detection unit  13 , and information for the front, moving vehicle detected by the image recognition unit  15 . At this time, as shown in  FIG. 2 , since the width information for the front, moving vehicle is provided as the unit of length (W in  FIG. 2 ) by the image recognition unit  15 , and the line-of-sight behavior of the driver is provided as the unit of angle, as shown in  FIG. 3 , the width W of the front, moving vehicle is converted into a value α, which is the unit of angle, in order to perform the calculations. This conversion is performed by using the following expression (1). 
       α=2·arctan(( W/ 2)/ L )  (1) 
     Further, a variance β, indicating the horizontal variance of the line-of-sight behavior relative to the front, moving vehicle, is calculated using information for the line-of-sight behavior of the driver. That is, an eye focal point on a virtual plane is calculated based on the rotation angle of the eyes, and when the horizontal element of the viewing point is denoted as x j , the horizontal variance β of the eye focal point over a specific time span [t 1 , t 2 ] (e.g., 30 to 60 seconds) is calculated by using the following expression (2). 
     
       
         
           
             
               
                 
                   β 
                   = 
                   
                     
                       ( 
                       
                         1 
                         / 
                         
                           ( 
                           
                             
                               t 
                               2 
                             
                             - 
                             
                               t 
                               1 
                             
                             + 
                             1 
                           
                           ) 
                         
                       
                       ) 
                     
                     · 
                     
                       
                         ∑ 
                         
                           j 
                           = 
                           
                             t 
                              
                             
                                 
                             
                              
                             1 
                           
                         
                         
                           t 
                            
                           
                               
                           
                            
                           2 
                         
                       
                        
                       
                         ( 
                         
                           
                             x 
                             j 
                             2 
                           
                           - 
                           
                             x 
                             a 
                             2 
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     In this case, xa is the average value, and is calculated by using the following expression (3). 
     
       
         
           
             
               
                 
                   
                     x 
                     a 
                   
                   = 
                   
                     
                       ( 
                       
                         1 
                         / 
                         
                           ( 
                           
                             
                               t 
                               2 
                             
                             - 
                             
                               t 
                               1 
                             
                             + 
                             1 
                           
                           ) 
                         
                       
                       ) 
                     
                     · 
                     
                       
                         ∑ 
                         
                           j 
                           = 
                           
                             t 
                              
                             
                                 
                             
                              
                             1 
                           
                         
                         
                           t 
                            
                           
                               
                           
                            
                           2 
                         
                       
                        
                       
                         x 
                         j 
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     As shown in expression (4) below, a standard deviation s x  may also be employed as a value indicating the variance in the line-of-sight behavior relative to the front, moving vehicle. 
     
       
         
           
             
               
                 
                   
                     s 
                     x 
                   
                   = 
                   
                     
                       ( 
                       
                         
                           ( 
                           
                             1 
                             / 
                             n 
                           
                           ) 
                         
                         · 
                         
                           
                             ∑ 
                             
                               j 
                               = 
                               
                                 t 
                                  
                                 
                                     
                                 
                                  
                                 1 
                               
                             
                             
                               t 
                                
                               
                                   
                               
                                
                               2 
                             
                           
                            
                           
                             ( 
                             
                               
                                 x 
                                 j 
                                 2 
                               
                               - 
                               
                                 x 
                                 a 
                                 2 
                               
                             
                             ) 
                           
                         
                       
                       ) 
                     
                     
                       1 
                       / 
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     The ratio of the width a of the front, moving vehicle to the variance β of the line-of-sight of the driver is calculated as the attentiveness evaluation value Sh (Sh=α/β), which represents the level of attentiveness, and the state of a driver is determined by comparing the attentiveness evaluation value Sh with a predesignated evaluation threshold value Shc. When the attentiveness evaluation value Sh is equal to or greater than the evaluation threshold value Shc (e.g., 0.1) (e.g., the case of a state β 1  in  FIG. 3 ), it is determined that the state of the driver is extremely-concentrating, which indicates that the attention given by a driver to a front, moving vehicle is strong, and the tension of the driver is high. When the attentiveness evaluation value Sh is smaller than the evaluation threshold value Shc (e.g., the case of a state β 2  in  FIG. 3 ), it is determined that the state of the driver is randomly scanning, which indicates the attention given by a driver to a front, moving vehicle is not more than is necessary, and the driver can adapt to a driving environment. 
     In the exemplary embodiment, the width W of the front, moving vehicle has been converted to the angle to calculate the attentiveness evaluation value Sh. However, the variance β of the line-of-sight behavior of the driver may be converted to the length at the position of the front, moving vehicle to calculate the attentiveness evaluation value Sh. 
     The fragrance generation device  20  mainly includes a control unit  21  that controls a fragrance emitting mechanism  25  for emitting, inside a vehicle, a fragrance emitted by an air freshener. At the time a door lock is released by the reception of a keyless unlock signal from a keyless door lock device  100 , or in accordance with the driver state received from the driver state determination unit  16 , the control unit  21  permits the fragrance emitting mechanism  25  to emit a predetermined fragrance inside the vehicle. In this embodiment, a relaxing air freshener  30  having an orange aroma has a soothing effect on a driver&#39;s nerves and an awakening air freshener  31  having a mint aroma that has and awakening effect are prepared. The relaxing air freshener  30  is mainly employed, and as needed, the awakening air freshener  31  is employed. 
     The fragrance emitting mechanism  25  is a blowing system wherein a blowing fan  26  is arranged inside a dashboard, for example, in the front of a vehicle compartment, and using the blowing fan  26 , air is introduced to an air freshener through a selector valve  27  and switching valves  28  and  29 , so that a fragrance is sent forth to the inside of the vehicle. An intake passage  40  for the blowing fan  26  is opened at a predetermined portion of the compartment, e.g., at the foot of the passenger seat, and a blowoff passage  41  for the blowing fan  26  is branched to ventilation ducts  42  and  43  by the selector valve  27 . A perfume container  44  holding the relaxing air freshener  30  and a perfume container  45  holding the awakening air freshener  31  are respectively located along the ventilation ducts  42  and  43 , and these containers  44  and  45  are opened or closed by the switching valves  28  and  29 , respectively. 
     The indoor blowoff ports for the ventilation duct  42  are opened at positions such that the vehicle compartment can be faintly filled with the aroma of the relaxing air freshener  30  and the driver can be effectively relaxed. For example, as shown in  FIG. 4 , as fragrance blowoff ports for the relaxing air freshener  30 , an opening  46   a  and an opening  46   b  are respectively formed in an A pillar  50  on the driver side and in the upper portion of a meter visor  51 . On the other hand, the indoor blowoff port for the ventilation duct  43  is opened at a position such that the aroma of the awakening air freshener  31  is emitted directly into the face of a driver, especially near the nose, in order to actually awaken the driver. For example, as shown in  FIG. 4 , as the fragrance blowoff port for the awakening air freshener  31 , an opening  47  is formed in the upper portion of a column cover  53  that is the base of a steering wheel  52 . 
     It should be noted that the fragrance emitting mechanism  25  may be formed as part of an air conditioning system for a vehicle. 
     The control unit  21  generally maintains a state wherein the perfume container  45  in which the awakening air freshener  31  is stored is closed by the switching valve  29 , and the ventilation duct  43  is closed by the selector valve  27 . When the control unit  21  detects the door lock has been released by the reception of a keyless unlock signal from the keyless door locking device  100 , the control unit  21  determines an occupant has boarded the vehicle. Then, the control unit  21  opens the switching valve  28  over a predetermined period of time, and drives the blowing fan  26  to blow air to the ventilation duct  42 , so that a fragrance having a relaxing effect is generated from the relaxing air freshener  30  stored in the perfume container  44 . As a result, the fragrance spreads through the opening  46   a  of the A pillar  50  and the opening  46   b  in the upper portion of the meter visor  51 , so as to carry the fragrance faintly distributed in the air. 
     Further, when it is determined during driving that the driver is extremely-concentrating, the control unit  21  cyclically opens or closes the switching valve  28 , and cyclically extends the valve opening period to increase the amount (emitted fragrance amount) of the relaxing air freshener  30  that is discharged. Thus, the tension of the driver is quickly reduced, and the state of the driver is shifted to randomly scanning. 
     When the driver state has been shifted to randomly scanning, the control unit  21  shortens the valve opening period for the switching valve  28  and reduces the amount of the relaxing air freshener  30  discharged to maintain the random scanning state of the driver. 
     In addition, during the processing for reducing the amount of the relaxing air freshener  30  discharged to maintain random scanning, the control unit  21  opens, as needed, the switching valve  29  for the perfume container  45 , where the awakening air freshener  31  is stored, and blows air through the ventilation duct  43  by changing the selector valve  27 . In this manner, the awakening air freshener  31  is continuously discharged. 
     That is, when time has elapsed from the start of driving, the state of the driver adapts to the driving environment, and is shifted to randomly scanning, which indicates the tension is reduced subconsciously. However, when the tension of the driver is reduced too much, the driver would become drowsy, which indicates that the reduced alertness. Therefore, when the condition of the driver is randomly scanning, not, only a relaxing fragrance is intermittently emitted, but also an awakening fragrance. In this manner, the driver is kept from shifting from randomly scanning to drowsy, and the random scanning condition can be stably maintained. 
     The operation of the driving support system  1  is performed by the program processing in  FIGS. 5 and 6 . This program processing will now be described. 
     The driver state estimation processing performed by the driver state estimation device  10  is shown in the flowchart in  FIG. 5 . First, a necessary parameter is read at step S 1 . 
     Program control advances to step S 2 , and an image obtained by the external monitoring camera  14  is processed to extract a front, moving vehicle, and at step S 3 , width information for the front, moving vehicle is converted into an angle α. 
     Program control advances to step S 4 , and the average value of the line-of-sight behavior of the driver and the variance β consonant with this average value are calculated. At step S 5 , the ratio of the width a of the front running vehicle to the variance β of the line-of-sight behavior of the driver is calculated as the attentiveness evaluation value Sh representing the attentive state (Sh=α/β). At step S 6 , the attentiveness evaluation value Sh is compared with the predesignated evaluation threshold value Shc. 
     As a result, when the attentiveness evaluation value Sh is equal to or greater than the evaluation threshold value Shc, program control advances to step S 7 , and it is determined that the state of the driver is extremely-concentrating, which indicates the attention given to the front, moving vehicle is strong. Then, program control exits this processing. When the attentiveness evaluation value Sh is smaller than the evaluation threshold value Shc, program control is shifted to step S 8 , and it is determined that the driver is in the state (randomly scanning) indicating attention given to the front running car is not strong. Thereafter, program control exits this processing. 
     The results of the determination of the driver state are referred to in the fragrance emitting control processing shown in the flowchart in  FIG. 6 . 
     The fragrance emitting control processing is the processing performed by the control unit  21  of the fragrance generation device  20 . First, at step S 11 , the control unit  21  determines whether the door lock has been released by the reception of a keyless unlock signal. 
     When the door lock has not been released, program control advances from step S 11  to step S 13 . When the door lock has been released, it is determined that an occupant has boarded the vehicle, program control is shifted from step S 11  to S 12  and the control unit  21  opens the switching valve  28  for the perfume container  44 , where the relaxing air freshener  30  is stored, and drives the blowing fan  26 . Program control then is shifted to step S 13 . 
     At this time, through an action performed by the selector valve  27 , the blowoff passage of the blowing fan  26  communicates with the ventilation duct  42  for the relaxing air freshener  30 , and the ventilation duct  43  for the awakening air freshener  31  is closed. 
     As a result, a fragrance generated from the relaxing air freshener  30  is emitted inside the vehicle compartment, from the opening  46   a  of the A pillar  50  and from the opening  46   b  of the upper portion of the meter visor  51 . The period for emitting the fragrance of the relaxing air freshener  30  in the compartment is designated, for example, as a period from the time the door lock is released to the start of the engine, and the opening of the switching valve  28  and the air flow rate of the blowing fan  26  are set so that a faint aroma of the fragrance that has a relaxing effect released. 
     At step S 13 , the control unit  21  determines whether the engine has been started. When the engine has not yet been started, it is assumed that the vehicle is at a stop, with the doors closed, or is in the state existing before the engine starts following the release of the door lock. Therefore, program control exits the processing while the current status is maintained. When the engine has been started, program control advances to step S 14  where the control unit  21  reads the results obtained by the driver state estimation unit  10 , through the driver state estimation processing, and determines whether, during driving, the driver has become extremely-concentrating. 
     When it is determined that the driver is extremely-concentrating, program control is shifted from step S 14  to step S 15 , and the control unit  21  employs the switching valve  28  and the blowing fan  26  to emit the fragrance of the relaxing air freshener  30  through the opening  46   a  of the A pillar  50  and the opening  46   b  of the meter visor  51 . Thereafter, program control exits this processing. The amount of the relaxing air freshener  30  (emitted amount of the fragrance) to be discharged for the extremely-concentrating driver should be adjusted to an amount that will quickly reduce the tension of the driver. That is, as shown in  FIG. 7A , mainly the discharge of a fragrance and stopping of the discharge are cyclically repeated by intermittently opening or closing the switching valve  28 , and the valve open period (fragrance emitting period) during the cycle is relatively long while the valve closed period (fragrance discharge stopped period) is short. 
     On the other hand, when it is determined at step S 14  that the driver is not extremely-concentrating, program control advances from step S 14  to step S 16 , and the control unit determines whether the driver is randomly scanning. When it is determined that the driver is not randomly scanning, program control exits the processing while the current state is maintained. When the driver is randomly scanning, program control advances to step S 17 . 
     At step S 17 , the switching valve  28  and the blowing fan  26  are employed to discharge the fragrance of the relaxing air freshener  30  through the opening  46   a  of the A pillar  50  and the opening  46   b  in the upper portion of the meter visor  51 . The amount of the relaxing air freshener  30  to be discharged for the randomly scanning driver should be adjusted to smaller than the amount discharged for the extremely-concentrating driver, in order to maintain the random scanning state. That is, the valve open period (fragrance emitting period) of the switching valve  29  in the cycle is long, while the valve closed period (fragrance discharge stopped period) is short, and the fragrance discharged is so faint that the driver may not notice it. 
     Sequentially, program control advances to step S 18 , and temporarily, the control unit  21  employs the selector valve  27  to change the blowoff passage of the blowing fan  26  to the ventilation duct  43  for the awakening air freshener  31 , opens the switching valve  29 , and emits the fragrance of the awakening air freshener  31  through the opening  47  formed in the upper portion of the column cover  53 , which is the base of the steering wheel  52 . As the amount of the awakening air freshener  31  (the emitted amount of the fragrance) discharged for the randomly scanning driver, the fragrance spaying interval is set longer than that for the relaxing air freshener  30  for maintaining the random scanning condition. That is, as shown in  FIG. 7B , the fragrance of the awakening air freshener  31  is emitted, on and off, near the nose of the driver, and a reduction in the alertness of the driver can be prevented. 
     In this case, the timing for emitting of the fragrance of the awakening air freshener  31  can be determined based, for example, on a warning for zigzag driving. As is well known (see, for example, JP-A-2002-154345 or JP-A-2005-71184), a zigzag driving warning is generated by estimating the alertness level of a driver based on the frequency component of the transverse displacement of a vehicle. To prevent a reduction in the alertness of a driver, awakening effect fragrance need only be generated from the awakening air freshener  31  and be discharged into the compartment for a predetermined period (e.g., 60 seconds) by employing the occurrence of a zigzag driving warning as a reference time, and for a predetermined period (e.g., 30 seconds) employing, as a reference, the vicinity of a threshold value of the primary zigzag driving warning, or during a predetermined period (e.g., 60 seconds) employing, as a reference, the vicinity of the threshold value of the secondary zigzag driving warning. 
     Further, more simply, the process at step S 18  may be eliminated, and the amount of the relaxing air freshener  30  discharged may be adjusted, so that the random scanning condition of the driver can be maintained without employing the awakening air freshener  31 . That is, to prevent shifting from randomly scanning to drowsy, as shown in  FIG. 7C , a shorter period than that in  FIG. 7B  is set for emitting of the relaxing air freshener  30 , or the discharge interval is extended. When the awakening air freshener  31  is not employed, the structure of the fragrance emitting mechanism  25  can be simplified, and the system cost can be reduced. 
     As described above, in the first exemplary embodiment, when the line-of-sight behavior of a driver is employed to determine that the driver is extremely-concentrating, which indicates high tension, a fragrance that has a relaxing effect is emitted into the compartment of a vehicle to reduce the tension of the driver, and to quickly shift from extremely-concentrating to randomly scanning. Therefore, the driving support system supports the driver and assists the driver in adapting to the driving environment, and helps in the improvement of safety. 
     When the driver is randomly scanning, a fragrance that has relaxing effect is faintly distributed within the compartment to maintain random scanning. Further, since the fragrance that has an awakening effect is discharged, as needed, a reduction in alertness can be prevented and the random scanning state can be steadily maintained. Thus, the driving support system supports the optimization of the driving state. 
     A second exemplary embodiment of the invention will now be described.  FIGS. 8 and 9  relate to the second exemplary embodiment of the invention, i.e.,  FIG. 8  is a flowchart for the driver state determination processing and  FIG. 9  is a flowchart for the fragrance emit control processing. 
     In the first exemplary embodiment, when the driver is randomly scanning, the awakening air freshener  31  is discharged, as needed, in order to prevent a reduction in the tension of the driver and a change to drowsy. According to the second exemplary embodiment, whether the driver is shifted from randomly scanning to drowsy is determined, and the discharge of the awakening air freshener  31  is controlled in accordance with the determination results. 
     That is, according to the second exemplary embodiment, the driver state determination processing in  FIG. 8 , which is a more detailed processing than that in  FIG. 5  for the first exemplary embodiment, is performed to determine more driver states, i.e., extremely-concentrating, randomly scanning and drowsy. 
     In the driver state determination processing in  FIG. 8  for the second exemplary embodiment, processes at steps S 6 - 1  and S 6 - 2  for determining whether a driver is drowsy are additionally provided for the processing in  FIG. 6 , when, at step S 6 , the driver is randomly scanning and not extremely-concentrating, i.e., the attentiveness evaluation value Sh is smaller than the evaluation threshold value Shc. 
     Specifically, at step S 6 - 1 , an alertness evaluation value Kh, indicating the alertness level of a driver, is calculated using expression (5), for example, and at step S 6 - 2 , is compared with a predesignated threshold value Khc. When the alertness evaluation value Kh is equal to or greater than the threshold value Khc, program control is shifted from step S 6 - 2  to step S 8 , and it is determined that the driver is randomly scanning. 
     When the alertness evaluation value Kh is smaller than the threshold value Khc, program control advances from step S 6 - 2  to step S 9 , and it is determined that the driver is in the drowsy state. 
         Kh ={(number of times eyes closed longer than a blink)/(the total number of blinks)}  (5) 
     For evaluation of alertness, instead of the alertness evaluation value Kh using expression (5), the vehicle driving condition of a driver (the manipulation of a steering wheel) may be referred to. That is, when the driver is alert, vehicle movements are generated with a high frequency and a small amplitude, while when the driver is drowsy, fluctuations occur with a low frequency and a large amplitude. This vehicle movement may also be referred to for the evaluation of alertness. 
     In the fragrance emitting control processing in  FIG. 9  for the second exemplary embodiment, when the random scanning state is obtained through a determination performed in the same manner as in the first exemplary embodiment (see in  FIG. 6 ), and when, at step S 17 , the relaxing air freshener  30  is discharged, program control advances to step S 19  to determine whether the driver is drowsy. 
     When it is determined that the driver is not drowsy, program control exits the processing, while the state of the relaxing air freshener  30  discharged in the randomly scanning condition is maintained. When it is determined that the driver is drowsy, program control advances to step S 20 . The process at step S 20  corresponds to step S 18  in the fragrance emitting control processing of the first exemplary embodiment. In the same manner as in the first exemplary embodiment, a selector valve  27  is employed to change the blowoff passage of a blowing fan  26  to a ventilation duct  43  for the awakening air freshener  31 , and a switching valve  29  is opened to emit the awakening air freshener  31  through an opening  47 , which is formed in the upper portion of a column cover  53  at the base of a steering wheel  52 . The same amount of the awakening air freshener  31  as in the first exemplary embodiment may be discharged. However, since it has been determined that the driver is drowsy, it is preferable that a slightly larger amount be discharged to quickly avoid a reduction in alertness. 
     According to the second exemplary embodiment, the driver in the random scanning state is examined based on the line-of-sight behavior and the driving condition, and when it is determined that the driver is drowsy, a fragrance having an awakening effect is discharged into the compartment of a vehicle. Therefore, the driving support system can more effectively prevent a reduction in the alertness of the driver, and can increase driving safety.