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Functional description

The following graphic shows the functional concept of the Head-Up Display.

Fig 1: Head Up Display Functional Diagram
G10092673Courtesy of BMW OF NORTH AMERICA, INC.
Item Explanation
1 Representation of virtual image
2 Viewing angle
3 Head-Up Display
4 Projection display
5 Windscreen
6 Driver's eyes
7 Folding mirror
8 Pivoting mirror
9 Light source

The horizontal alignment of the virtual image can be adjusted using the controller. The controller is also used to select the information to be displayed. The Head-Up Display brightness can be adjusted in the central information display using the controller. Via the controller the Head-Up Display image can be turned horizontally with help of the display rotation in the central information display.

As an example, the following graphic shows the Head-Up Display menu in the central information display.

Fig 2: Display - Head Up Display Menu Screen
G10092674Courtesy of BMW OF NORTH AMERICA, INC.

The following functions of the Head-Up Display are described:

Switching on 

The Head-Up Display is switched on or off in the Settings menu using the checkbox "Head-Up Display" in the central information display. To protect the projection display against direct solar radiation when parked, one mirror is swivelled away while the vehicle is going to sleep. As of terminal 30B ON, the mirror is swivelled from the parked position into the beam path. The Head-Up Display is partially operational when terminal R is switched ON. That means:

The Head-Up Display is operational when terminal 15 is switched ON. That means:

Projection 

The Head-Up Display projects a virtual image that seems to be generated in the air without a fixed image carrier. The image is generated on a projection display in the Head-Up Display and deflected by the windscreen in such a way that the driver sees the image floating above the engine compartment lid. The size of the virtual image is approx. 22 x 6.5 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 the 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 adaptation of the display brightness depends on the ambient brightness, the brightness adjustment and the dimmer setting of the instrument lighting (only with light ON) or the brightness setting in the Personal Profile of the Head-Up Display. The ambient brightness (day, night, twilight, sunshine, etc.) is recorded by the rain-light-solar-condensation sensor. This also picks up the brightness in the area of the virtual image to ensure optimal brightness control.

When the lighting is switched on (locator lighting, lights ON) the brightness of the Head-Up Display is also influenced by the dimmer setting of the instrument lighting or the brightness setting in the Personal Profile of the Head-Up Display. The brightness adjustment takes into account the individual brightness setting for the Head-Up Display, deviating from the basic setting. The individual brightness setting is made on the central information display using the controller. The set value is stored in the Personal Profile in the Head-Up Display.

Prioritisation of displays, switch-on characteristics 

The information in the Head-Up Display is classified according to importance for the driver. Displays with low priority are overwritten by displays with higher priority.

Image generation 

The picture signals for the screen mask are transferred from the instrument cluster (KOMBI) via the LVDS data line to the Head-Up Display. The switch-on and switch-off signal as well as the information for the screen mask are output by the corresponding control units (headunit) as a bus signal. The instrument cluster evaluates the bus signals received via the PT-CAN and forwards the information to the components of the Head-Up Display.

The background color of the Head-Up Display is black. The contents of the Head-Up Display are displayed as follows:

The size of the display area for the virtual image is approx. 22 x 6.5 cm (width x height). The display area is split vertically to assist in the display content. Instructions given by the navigation system and Check Control messages are displayed on the right. Speed-related information is displayed on the left. Which display content is shown is set in the central information display using the controller.

Display area setting 

The virtual image can only be viewed completely and properly from a certain area on the driver's side. Outside this area, it is not possible to view the virtual image completely. The height of the position of the virtual image can be shifted (± 5 cm). In this way, the user can alter the determined area by horizontal height adjustment and adapt it to his/her requirements (via central information display and controller).

Vertical rotation of Head-Up Display 

The Head-Up Display is supplied ex works with a defined basic setting.

With help of the display rotation the Head-Up Display image can be turned horizontally, for example after a disc change, via the central information display. The display can then be readjusted in steps of approx. 0.004° from -3° to +3° by an electric motor.

Switch off 

The Head-Up Display is switched on or off using the controller. If terminal 15 is off, the Head-Up Display is also switched off.

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