Functional Description

Functional Description








The HUD can be compared to a projection device. An LED field is required as the light source for the purpose of projecting the HUD information. The image content is created by the TFT projection display. The TFT projection display can be compared to a filter which admits or blocks light. An optical imaging element determines the shape and size of the HUD images. The image is projected onto the windscreen and appears freely suspended over the road surface.

Mirror





The HUD incorporates four mirrors. These mirrors reflect the display content onto the windscreen. Three of the mirrors are curved. These mirrors adapt the display content to the screen.
This mirror determines the size and distance of the HUD projection. The curved mirrors are made of plastic while the plane mirror is made of glass.
The course of projection is shown in the following illustration.
The projected HUD image content appears at a distance of approximately 2.2 m from the eye.

Eyebox





The eye box is the movement space in which the driver can move without his view of the image in the HUD being impaired.
The freedom of movement within the eye box is roughly:
^ 130 mm horizontally
^ 90 mm vertically
Outside the eye box limits the image in the HUD is no longer clearly visible.

Windshield





The windshield is a special windshield and is an integral component vital to projecting the displays. The outer and inner glass panes are connected to a plastic film, which is wedge shaped over the entire length of the windshield.

The wedge-shape prevents double displays (ghosts) of the HUD by positioning both images one above the other. The wedge tip points downward and starts at a distance of approximately10 cm to the bottom edge of the windshield.

The end of the wedge is located at approximately 2/3 windshield height. In the top third of the windshield, the plastic film runs parallel to the outer and inner glass panes. The thickness of the wedge tip is 0.8 mm. The thickness of the end of the wedge is 1 mm.

If a nonspecified (normal) windshield is used, the image is reflected on both the outer and inner glass panes. Overlapping causes the image to be displayed twice. The plastic wedge in the windshield places the images of the outer and inner pane over each other thus preventing double displays (ghosts).

Color Selection

The HUD background color is transparent.
Symbols (such as e.g. warning symbols) are specified by the individual control units. This color specification is adopted for the display in the HUD.
2D symbols are used for optimum visibility and legibility.
The colors are:
^ Orange as the standard color
^ Red or yellow for warning messages
^ Green for the setting speed


Light Switch with Operating Unit

The HUD button is located in the operating unit. The control button is resistance coded and routed directly to the HUD. The HUD can identify the button signals or a button fault using the resistance coding.

Instrument Lighting Dimmer

The dimmer setting is also used for the HUD with active headlights. The dimmer signal is emitted by the light module.


Adjusting HUD Brightness

The brightness of the HUD can be individually adjusted. The CID is the display instrument and the controller the control element for brightness adjustment.
The brightness offset is adjusted from the main menu as follows:
The main menu is activated as soon as terminal 15 is on.
^ Press the controller, the Settings menu will appear.
^ Select Display settings and confirm
^ Select Brightness of head-up display and confirm
^ Set brightness and confirm the entry by pressing the controller.