System functions

The head-up display comprises the following functions:

• Switch-on response
• Projection of virtual image in front of the vehicle
• Automatic adaptation of display brightness
• Prioritization of displays

  Switch-on response 

  The head-up display is partially operational when terminal R is switched ON. This means:

  • The projection display is initialized but information is not yet displayed.
  • The head-up display is able to communicate with other bus-elements via the MOST and K-CAN data buses.

  The head-up display is operational when terminal 15 is switched ON. This means:

  • The light source is switched on when the button for switching the head-up display on and off is pressed.
  • The projection display cover panel is folded out of the beam by the stepper motor.
    • E70

    The E70 has no cover panel for the projection display. One mirror is swivelled away to protect the display against direct sunlight when parked. As from terminal 15 ON the mirror is swivelled from the park position into the position stored by the Car and Key Memory.

  • The automatic adaptation of the display brightness is activated.
  • E70

    The image orientation of the virtual image can be height-adjusted.

  Projection of virtual image in front of the vehicle 

  The head-up display projects a virtual image, i.e. an image that appears to hang in mid-air without a fixed image carrier (e.g. projection screen or similar).

  The image is generated on a projection display in the head-up display and deflected by the windscreen in such a way that driver seemingly sees the image floating above the bonnet. (The effect of the virtual image is the same as when looking in a mirror: the observer looks not at the mirror but behind the mirror.)

  The size of the virtual image is approx. 20 x 10 cm (width x height). The virtual image can only be seen from a defined area from the driver's side.

  Automatic adaptation of display brightness 

  The automatic adaptation of display brightness prevents major sudden changes in the brightness of the head-up display when the vehicle moves between different ambient lighting conditions (e.g. from light to dark and from dark to light when driving through a tunnel).

  The automatic adjustment of the display brightness depends on

  • the ambient lighting conditions,
  • the brightness adjustment setting,
  • the dimmer setting for instrument lighting (only when the lights are on).

  The surrounding brightness (day, night, twilight, sunshine, etc.) is recorded by the rain/light sensor. The value of the brightness adjustment (difference between base setting and individually set display brightness) is stored in the head-up display. When the lighting is switched on (terminal 58g, lights ON) the brightness of the head-up display is also influenced by the dimmer setting of the instrument lighting.

  Prioritization of displays 

  The information in the head-up display is classified according to priority (= importance for the driver). Displays with low priority are overwritten by displays with higher priority.

  PRIORITY FUNCTION CHART
  
  

  Priority	Function
  1	Warnings from Active Cruise Control (ACC)
  2	Check-Control messages
  3	Test functions (= aids when troubleshooting without BMW diagnosis system)
  4	Navigation instructions