Patent Publication Number: US-2023158864-A1

Title: Vehicle compartment with smart glass controlled by a light sensor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit of priority to European Patent Application No. 21209509.5, filed Nov. 22, 2021, and is assigned to the same assignee as the present application and is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The disclosure relates to a vehicle compartment with a system for mitigating blinding of a vehicle occupant. Specifically, the disclosure can be applied in any vehicle with a vehicle compartment in which a driver or passenger risks being blinded by the sun, such as trucks, buses, construction equipment and cars. 
     BACKGROUND 
     When operating or riding a vehicle, an occupant operating or riding the vehicle stands the risk of being blinded by the sun. A common solution to the problem is to provide a manually operated sun visor, curtain or similar device in the vehicle. Such manually operated devices requires an effort by the occupant, thereby distracting him/her. Further, the occupant may enable it/fold it down too late or not at all. Also, there is a risk that the device remains enabled/folded down too long, thereby reducing the field of view of the occupant when not needed. 
     WO201788963A1 discloses an automated approach for mitigating light sources blinding a passenger. Specifically, the solution is based on use of screens with electrically controllable light transmission properties, such as a screen or layer of electrochromic glass or liquid crystal layer or other type of electrically switchable smart glass. The proposed solution monitors occurrence of a glare situation, for example using optical sensors. Alternatively, the system can be manually enabled by a signal from a manual control element. When a glare situation is detected, a transmittance of the screen, in at least parts of the screen, is reduced to reduce the object’s brightness perceivable by the passenger. A drawback of this system is that it is complex. 
     DE102005007427 discloses an automatic sun visor system for a vehicle. The system comprises a plurality of segments comprising, e.g., a smart film (SPD or PDLC film) which may be arranged on/at a windscreen. The transparency of each segment can be set individually and is set based on input from sensors, such as a light sensor. The light sensor is positioned on the outside of the vehicle. The control of the segments is further based on input concerning the position, more specifically the height, of the eyes of a person sitting in the vehicle, which may be detected by sensors inside the vehicle. 
     DE10057795 discloses an automatic sun visor system for a vehicle. The system comprises a smart panel. The transparency of the panel may be adjusted automatically based on input from a light sensor. The panel is further controlled based on the head position of a driver and the position and direction of the vehicle. A drawback of this system is that it is complex. 
     SUMMARY 
     An object of the disclosure is to provide a simple automated system for mitigating blinding of a vehicle occupant by the sun. According to a first aspect of the present disclosure, this and other objects are achieved by a vehicle compartment for a vehicle, said vehicle compartment being adapted to accommodate an occupant of said vehicle. The vehicle compartment has a vertical extent in a vertical direction and comprises a screen through which the occupant can view at least portions of the environment ambient of said vehicle compartment. The vehicle compartment further comprises a panel assembly comprising at least one panel. Each panel in said panel assembly is adapted to adjust the light intensity of light falling into said vehicle compartment via at least a portion of said screen. The vehicle compartment further comprises a light sensor adapted to determine an intensity of light falling onto said light sensor via said screen. Also, the vehicle compartment comprises a control unit adapted to adjust at least one, preferably each, panel in said panel assembly, to thereby adjust the light intensity of light falling into said vehicle compartment via at least a portion of said screen, in response to a signal issued from the light sensor. The vehicle compartment further comprises a seat for the occupant, said seat being associated with a vertical eye position range indicating within which vertical eye position range, in said vertical direction, the eyes of said occupant are expected to be located when said occupant occupies said seat. The light sensor is located below, in said vertical direction, said vertical eye position range within a range of 10 - 20 cm. Further, said seat ( 8 ) comprises a main body ( 12 ) and a headrest ( 13 ), wherein said headrest ( 13 ) is adapted to receive at least a portion of the head of said occupant. Also, either:
     a) said headrest ( 13 ) comprises a proximal headrest portion ( 14 ) and a distal headrest portion ( 15 ), wherein said distal headrest portion ( 15 ) is located further away from said main body ( 12 ) than said proximal headrest portion ( 14 ) is, as measured in said vertical direction ( 2 ), said light sensor ( 6 ) being attached to said proximal headrest portion ( 14 ), or   (b) said main body ( 12 ) comprises a backrest ( 16 ) and said light sensor ( 6 ) is attached to said backrest ( 16 ).   

     As incoming sunlight shines towards the occupant, an upper portion of the vehicle compartment normally shades the occupant for some time until the shadow on the occupant moves upward as the sun moves to a lower incoming angle relative the travelling direction of the vehicle. Hence, the sunlit region of the compartment rises within the vehicle compartment until it finally approaches the eyes of the occupant and blinds the occupant. By providing a light sensor below, in said vertical direction, said vertical eye position range, the light sensor will receive the incoming sunlight before it risks blinding the occupant. Thereby, a simple and efficient means of mitigating blinding is provided. 
     The location of the light sensor below said vertical eye position range within a range of 10 - 20 cm has shown good results for sensing incoming light before it blinds the occupant. The provision of a headrest on the seat enables better control of the position of the head of the occupant during travel and thus enabling a more predictable result of the blinding prediction. 
     By attaching the light sensor to the backrest, the light sensor will move together with the backrest as the occupant moves the seat/backrest, for example by forward/rear adjustment or by rotation of the whole seat 180 degrees. Hence, the light sensing performed by the light sensor will adapt to the viewing direction and position/orientation of the occupant, thereby improving reliability and consistency of light measurements. 
     The vehicle compartment may further comprise a longitudinal extent in a longitudinal direction being parallel to an intended direction of travel of said vehicle, wherein the seat is associated with a longitudinal eye position range indicating within which longitudinal eye position range, in said longitudinal direction, the eyes of said occupant are expected to be located when said occupant occupies said seat. Also, the light sensor may be located behind, in said longitudinal direction, said longitudinal eye position range. 
     By locating the light sensor behind, in said longitudinal direction, said longitudinal eye position range, the light detection is made at a position both behind and below the eyes of the occupant, the risk of the sensor getting covered by the arms of the occupant is reduced, thus increasing reliability of the light sensing. 
     The headrest may be vertically moveable relative to said main body. 
     The vertical movability of the headrest enables it to better support and position the head of the occupant, thus enabling a more predictable result of the blinding prediction. 
     The backrest may comprise an upper backrest portion in said vertical direction, wherein the light sensor is attached to said upper backrest portion. 
     By attaching the light sensor to the upper backrest portion, the light sensor is located below said vertical eye position range, close enough to the occupant’s eyes to sense a change between a shaded situation and a sunlit situation, which in turn enables an automated activation of the sunblind prior to the occupant being blinded by the sun. 
     Each panel in said panel assembly may have an adjustable transparency to thereby be adapted to adjust the light intensity of light falling into said vehicle compartment via at least a portion of said screen. The control unit is adapted to adjust the transparency of each panel in said panel assembly to thereby adjust the light intensity of light falling into said vehicle compartment via at least a portion of said screen, in response to a signal issued from the light sensor. The controller thus uses information from the light sensor to detect a change from a shaded situation to a sunlit situation, and subsequently lowers the intensity of light falling into the vehicle compartment. The provision of a plurality of panels individually controllable by the control unit, enables not only varying the light intensity of light passing the panel assembly, but also enables varying what portions of the vehicle compartment the panel assembly shades by selectively activating individual panels to limit light transmission only through the activated panels whilst light is free to pass through the other panels. 
     Each panel in said panel assembly may be located on at least a portion of said screen. Locating the panels(s) on the screen, enables easy attachment of the panels to the vehicle/vehicle compartment by simply attaching the screen to the vehicle compartment. 
     The vehicle compartment may comprise a set of screens, said set of screens comprising at least two screens, through each one of which the occupant is able to view at least portions of the environment ambient of said vehicle compartment. Said vehicle compartment may further comprise a panel assembly for each screen in said set of screens, said panel assembly comprising at least a panel, located on at least a portion of said screen, each panel in said panel assembly being adapted to adjust the light intensity of light falling into said vehicle compartment via at least a portion of said screen. The provision of multiple screens enables use of screens in multiple viewing directions of the vehicle for shielding an occupant from incoming light from different viewing directions. 
     The vehicle compartment may comprise a condition sensor adapted to issue a condition signal to said control unit, said condition signal being indicative of which screen in said set of screens the occupant of said seat is currently facing, said control unit being adapted to adjust each panel in said panel assembly associated with the screen that the occupant of said seat is currently facing, to thereby adjust the light intensity of light falling into said vehicle compartment via at least a portion of that screen, in response to a signal issued from the light sensor. 
     The condition sensor enables control of only those panels which are in the direction which the occupant is currently facing such that adjustment of light transmittance needs not be made in all directions simultaneously but only in the direction the occupant faces. 
     The seat may be pivotable around a pivot axis parallel to said vertical direction such that an angular position of said seat is alterable. The condition sensor is adapted to determine said angular position and to issue said condition signal in response to said determined angular position. The angular position of the seat typically corresponds to the viewing direction of the occupant, thereby enabling an easy and reliable means for estimating the viewing direction of the occupant seated in the seat. 
     A further aspect of the present disclosure relates to a vehicle comprising a vehicle compartment as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the disclosure will below be described with reference to the appended drawings. 
         FIG.  1    is a side view of a vehicle compartment with incoming sunlight from a higher position from which the sun is not capable of blinding the occupant. 
         FIG.  2    is a side view of the vehicle compartment of  FIG.  1   , however shown with incoming sunlight from a lower position from which the sun risks blinding the occupant. Here, the light sensor has detected a change from being shaded to being exposed to incoming sunlight and the control unit has adjusted at least one panel in the panel assembly accordingly to thereby adjust (lower) the light intensity of light falling into said vehicle compartment to mitigate blinding by incoming light. 
         FIG.  3    is a perspective view from above showing a vehicle comprising a vehicle compartment as claimed. 
         FIG.  4    is a schematic view showing a panel assembly comprising five panels. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE DISCLOSURE 
     A first embodiment of a vehicle compartment is hereinafter described with reference to  FIGS.  1 - 4   . Although  FIG.  3    depicts a vehicle in the form of a truck, it should be understood the disclosure is equally well applicable for many other types of vehicles, such as buses, construction equipment and cars, including autonomous cars and buses. 
     As shown in  FIGS.  1 - 2   , the vehicle compartment  1  is a portion of the vehicle  21  adapted to accommodate at least one occupant of the vehicle  21 . In  FIGS.  1 - 2   , the occupant is shown as the driver of the vehicle  21 , but the occupant could alternatively or additionally be a passenger. The vehicle compartment  1  has a vertical extent in a vertical direction  2  and comprises a screen  3  through which the occupant can view at least portions of the environment ambient of said vehicle compartment  1 . The vehicle compartment  1  further comprises a panel assembly  4  comprising a plurality of panels  5 . Each panel  5  in said panel assembly  4  is adapted to adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 , for example by reflecting incoming light, by redirecting/scattering light, or by absorbing light. Also, the vehicle compartment  1  comprises a light sensor  6  adapted to determine an intensity of light falling onto said light sensor  6  via said screen  3 . Further, the vehicle compartment  1  comprises a control unit  7  adapted to adjust at least one, preferably each, panel  5  in said panel assembly  4 , to thereby adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 , in response to a signal issued from the light sensor  6 . The vehicle compartment  1  also comprises a seat  8  for the occupant, said seat  8  being associated with a vertical eye position range  9  indicating within which vertical eye position range  9 , in said vertical direction  2 , the eyes of said occupant are expected to be located when said occupant occupies said seat  8 . The light sensor  6  is located below, in said vertical direction  2 , said vertical eye position range  9 . 
     As incoming sunlight shines towards the occupant, an upper portion of the vehicle compartment  1  normally shades the occupant for some time until the shadow on the occupant moves upward as the sun moves to a lower incoming angle relative the travelling direction of the vehicle  21 . Hence, the sunlit region of the compartment  1  rises within the vehicle compartment  1  until it finally approaches the eyes of the occupant and blinds the occupant. By providing a light sensor  6  below, in said vertical direction  2 , said vertical eye position range  9 , the light sensor  6  will receive the incoming sunlight before it risks blinding the occupant. Thereby, a simple and efficient means of mitigating blinding is provided. 
     The seat  8  comprises a main body  12  and a headrest  13 . The headrest  13  is adapted to receive at least a portion of the head of said occupant. The provision of a headrest  13  on the seat  8  enables better control of the position of the head of the occupant during travel and thus enabling a more predictable result of the prediction of blinding. In other embodiments, the headrest may alternatively be omitted. 
     The headrest  13  is vertically moveable relative to said main body  12  but may in other embodiments alternatively be fixed relative to the main body  12  or integrated with the main body  12 . The vertical movability of the headrest  13  enables it to better support and position the head of the occupant, thus enabling a more predictable result of the prediction of blinding. 
     The headrest  13  comprises a proximal headrest portion  14  and a distal headrest portion  15 . The distal headrest portion  15  is located further away from said main body  12  than said proximal headrest portion  14  is, as measured in said vertical direction  2 , said light sensor  6  being attached to said proximal headrest portion  14 . 
     In this embodiment, the light sensor  6  is located about 15 cm below said vertical eye position range  9 . In other embodiments, the light sensor  6  may alternatively be positioned within a range of 5 - 40 cm, preferably within a range of 10 - 20 cm below said vertical eye position range  9 . Such a positioning of the light sensor  6  has shown good results for sensing incoming light before it blinds the occupant. 
     The vehicle compartment  1  further comprises a longitudinal extent in a longitudinal direction  10  being parallel to an intended direction of travel of said vehicle  21 . The seat  8  is associated with a longitudinal eye position range  11  indicating within which longitudinal eye position range  11 , in said longitudinal direction  10 , the eyes of said occupant are expected to be located when said occupant occupies said seat  8 . The light sensor  6  is located behind, in said longitudinal direction  10 , said longitudinal eye position range  11 , but may in other embodiments alternatively be otherwise positioned. 
     By locating the light sensor behind, in said longitudinal direction  10 , said longitudinal eye position range  11 , the light detection is made at a position both behind and below the eyes of the occupant, the risk of the sensor getting covered by the arms of the occupant is reduced, thus increasing reliability of the light sensing. 
     In other embodiments the light sensor  6  may alternatively be attached to a backrest  16  of the main body  12  of the seat  8 . This configuration works both for seats  8  with headrest  13  and for seats  8  without headrest. Specifically, the light sensor  6  may be attached to an upper backrest portion  17  in said vertical direction  2  of said backrest  16 . 
     Since the light sensor  6  is attached to the backrest  16 , the light sensor  6  will move together with the backrest  16  as the occupant moves the seat  8 /backrest  16 , for example by forward/rear adjustment or by rotation of the whole seat  8  180 degrees. Hence, the light sensing performed by the light sensor  6  will adapt to the viewing direction and position/orientation of the occupant, thereby improving reliability and consistency of light measurements. By attaching the light sensor  6  to the upper backrest portion  17 , the light sensor  6  is located below said vertical eye position range  9 , close enough to the occupant’s eyes to sense a change between a shaded situation and a sunlit situation, which in turn enables an automated activation of the sunblind prior to the occupant being blinded by the sun. 
     Each panel  5  in said panel assembly  4  has an adjustable transparency to thereby be adapted to adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 . The control unit  7  is adapted to adjust the transparency of each panel  5  in said panel assembly  4  in response to a signal issued from the light sensor  6 . 
     In this embodiment, each panel  5  has electrically controllable light transmission properties, such as a layer of electrochromic glass or liquid crystal layer or other type of electrically switchable glass, sometimes referred to as smart glass. However, the panel assembly  4  could in other embodiments alternatively comprise any other suitable means enabling the panel assembly  4  to adjust light intensity of light falling into the vehicle compartment  1  via at least a portion of the screen  3 , such as a mechanically operable blind (may for example be a roller blind or a pleated blind) or a movable sun visor. 
     In the embodiment shown in  FIGS.  1 - 3   , the vehicle compartment  1  comprises a set of screens  18 , said set of screens  18  comprising the windscreen of the vehicle  21 , the lefthand side window of the vehicle  21 , and the right-hand side window of the vehicle  21  (not visible in  FIGS.  1 - 3   ). 
     Each screen  3  of said set of screens  18  comprises a respective panel assembly  4 . Each panel assembly  4  comprises a plurality of vertically distributed panels  5  which are individually operable by adjustment of the light transmission of each respective panel  5 , thereby enabling the control unit  7  to vertically vary the amount of light transmitted through each respective panel assembly  4 . In other embodiments, only one of the screens  3  may be provided with a panel assembly  4 , such as the windscreen. 
     The vehicle compartment  1  comprises a condition sensor  19  adapted to issue a condition signal to said control unit  7 , said condition signal being indicative of which screen  3  in said set of screens  18  the occupant of said seat  8  is currently facing. The control unit  7  is adapted to adjust each panel  5  in said panel assembly  4  associated with the screen  3  that the occupant of said seat  8  is currently facing, to thereby adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of that screen  3 , in response to a signal issued from the light sensor  6 . The condition sensor  19  enables control of only those panels  5  which are in the direction which the occupant is currently facing such that adjustment of light transmittance needs not be made in all directions simultaneously but only in the direction the occupant faces. 
     The seat  8  is rotatable/pivotable around a pivot axis  20  parallel to the vertical direction  2  such that an angular position of the seat  8  is alterable. The condition sensor  19  is adapted to determine the angular position of the seat  8  and to issue the condition signal in response to the determined angular position. The angular position of the seat  8  typically corresponds to the viewing direction of the occupant, thereby enabling an easy and reliable means for estimating the viewing direction of the occupant seated in the seat  8 . 
     In other embodiments, the condition sensor  19  could alternatively be configured to determine if the seat  8  is rotated to be positioned in either one of a plurality of predetermined positions, for example by microswitches or other suitable type of sensors at each position. Alternatively, the condition sensor  19  could be one or more camera units adapted to optically monitor the occupant in order to determine the viewing direction of the occupant using image analysis, for example image analysis using feature detection and/or AI. In other embodiments, the condition sensor may alternatively be omitted. 
     It is to be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. 
     Examples Related to Embodiments Herein 
     Example 1: A vehicle compartment  1  for a vehicle, said vehicle compartment  1  being adapted to accommodate an occupant of said vehicle, 
     said vehicle compartment  1  having a vertical extent in a vertical direction  2 ,   said vehicle compartment  1  comprising a screen  3  through which the occupant can view at least portions of the environment ambient of said vehicle compartment  1 ,   said vehicle compartment  1  further comprising a panel assembly  4 , comprising at least one panel  5 , each panel  5  in said panel assembly  4  being adapted to adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 ,   said vehicle compartment  1  comprising a light sensor  6  adapted to determine an intensity of light falling onto said light sensor  6  via said screen  3 ,   wherein said vehicle compartment  1  further comprises a control unit  7  adapted to adjust at least one, preferably each, panel  5  in said panel assembly  4 , to thereby adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 , in response to a signal issued from the light sensor  6 ,   said vehicle compartment  1  further comprising a seat  8  for the occupant, said seat  8  being associated with a vertical eye position range  9  indicating within which vertical eye position range  9 , in said vertical direction  2 , the eyes of said occupant are expected to be located when said occupant occupies said seat  8 ,   wherein said light sensor  6  is located below, in said vertical direction  2 , said vertical eye position range  9 .   

     Example 2: The vehicle compartment  1  according to example 1, wherein said light sensor  6  is located below said vertical eye position range  9  within a range of 5 - 40 cm, preferably within a range of 10 - 20 cm. 
     Example 3: The vehicle compartment  1  according to any one of example 1 or example 2, wherein said vehicle compartment  1  further comprises a longitudinal extent in a longitudinal direction  10  being parallel to an intended direction of travel of said vehicle, said seat  8  further being associated with a longitudinal eye position range  11  indicating within which longitudinal eye position range  11 , in said longitudinal direction  10 , the eyes of said occupant are expected to be located when said occupant occupies said seat  8 , wherein the light sensor  6  is located behind, in said longitudinal direction  10 , said longitudinal eye position range  11 . 
     Example 4: The vehicle compartment  1  according to any one of examples 1-3, wherein said seat  8  comprises a main body  12  and a headrest  13 , wherein said headrest  13  is adapted to receive at least a portion of the head of said occupant. 
     Example 5: The vehicle compartment  1  according to example 4, wherein said headrest  13  is vertically moveable relative to said main body  12 . 
     Example 6: The vehicle compartment  1  according to example 4 or example 5, wherein said headrest  13  comprises a proximal headrest portion  14  and a distal headrest portion  15 , wherein said distal headrest portion  15  is located further away from said main body  12  than said proximal headrest portion  14  is, as measured in said vertical direction  2 , said light sensor  6  being attached to said proximal headrest portion  14 . 
     Example 7: The vehicle compartment  1  according to example 4 or example 5, wherein said main body  12  comprises a backrest  16  and said light sensor  6  is attached to said backrest  16 . 
     Example 8: The vehicle compartment  1  according to example 7, wherein said backrest  16  comprises an upper backrest portion  17  in said vertical direction  2 , said light sensor  6  being attached to said upper backrest portion  17 . 
     Example 9: The vehicle compartment  1  according to any one of examples 1-8, wherein each panel  5  in said panel assembly  4  has an adjustable transparency to thereby be adapted to adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 , said control unit  7  being adapted to adjust the transparency of each panel  5  in said panel assembly  4  to thereby adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 , in response to a signal issued from the light sensor  6 . 
     Example 10: The vehicle compartment  1  according to claim  9 , wherein each panel  5  in said panel assembly  4  is located on at least a portion of said screen  3 . 
     Example 11: The vehicle compartment  1  according to any one of examples 1-10, wherein said vehicle compartment  1  comprises a set of screens  18 , said set of screens  18  comprising at least two screens  3 , through each one of which the occupant is able to view at least portions of the environment ambient of said vehicle compartment  1 , said vehicle compartment  1  further comprising a panel assembly  4  for each screen  3  in said set of screens  18 , said panel assembly  4  comprising at least a panel  5 , located on at least a portion of said screen  3 , each panel  5  in said panel assembly  4  being adapted to adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of said screen  3 . 
     Example 12: The vehicle compartment  1  according to example 11, wherein said vehicle compartment  1  comprises a condition sensor  19  adapted to issue a condition signal to said control unit  7 , said condition signal being indicative of which screen  3  in said set of screens  18  the occupant of said seat  8  is currently facing, said control unit  7  being adapted to adjust each panel  5  in said panel assembly  4  associated with the screen  3  that the occupant of said seat  8  is currently facing, to thereby adjust the light intensity of light falling into said vehicle compartment  1  via at least a portion of that screen  3 , in response to a signal issued from the light sensor  6 . 
     Example 13: The vehicle compartment  1  according to example 12, wherein said seat  8  is pivotable around a pivot axis  20  parallel to said vertical direction  2  such that an angular position of said seat  8  is alterable, said condition sensor  19  being adapted to determine said angular position and to issue said condition signal in response to said determined angular position. 
     Example 14: A vehicle  21  comprising a vehicle compartment  1  according to any one of examples 1-13. 
     
       
         
           
               
               
               
               
             
               
                 Table of reference numerals 
               
             
            
               
                 
                   1 
                 
                 vehicle compartment 
                 
                   12 
                 
                 main body 
               
               
                 
                   2 
                 
                 vertical direction 
                 
                   13 
                 
                 headrest 
               
               
                 
                   3 
                 
                 Screen 
                 
                   14 
                 
                 proximal headrest portion 
               
               
                 
                   4 
                 
                 panel assembly 
                 
                   15 
                 
                 distal headrest portion 
               
               
                 
                   5 
                 
                 panel 
                 
                   16 
                 
                 backrest 
               
               
                 
                   6 
                 
                 light sensor 
                 
                   17 
                 
                 upper backrest portion 
               
               
                 
                   7 
                 
                 control unit 
                 
                   18 
                 
                 set of screens 
               
               
                 
                   8 
                 
                 seat 
                 
                   19 
                 
                 condition sensor 
               
               
                 
                   9 
                 
                 vertical eye position range 
                 
                   20 
                 
                 pivot axis 
               
               
                 
                   10 
                 
                 longitudinal direction 
                 
                   21 
                 
                 vehicle 
               
               
                 
                   11 
                 
                 longitudinal eye position range