BMW 7 Series: System Component

The head-up display is fitted above the steering column, immediately behind the instrument cluster. It is fastened to the bulkhead supporting structure by three hexagon-head bolts.

Fig. 38: Identifying Carrier Bracket, Head-Up Display (HUD), Hexagonal Bolt On F01/F02

STEERING COLUMN LEGENDS

1. Carrier bracket
2. Head-up display HUD
3. Hexagon bolt

The head-up display comprises the following components:

• Cover glass
• Mirrors
• 2 LED arrays
• TFT projection display
• PCB
• Housing

The following components are required in addition to the components listed above:

• Windshield
• Light module and BEFAS
• Rain/light sensor
• Roof function Center and junction box
• HUD trim

The following controls are required to operate the HUD:

• On/Off button on the BEFAS
• Light switch in the light switch cluster
• Instrument-lighting dimmer
• Controller

Cover Glass

The cover glass is made from scratch-resistant, coated polycarbonate (PC) and forms the top cover of the HUD.

The cover glass protects the interior of the HUD against dust and objects accidentally placed on it.

The glass combined with the HUD trim are curved so that any incident light is not reflected back to the driver.

It also guarantees unobstructed projection of the display information onto the windshield without interference from stray light effects, for instance.

Fig. 39: Identifying Plane Mirror

Mirrors

Two mirrors are fitted in the head-up display. They reflect the information in the display onto the windshield.

The concave mirror (1) is responsible for compensating for the curvature of the windshield and for the size and distance of the image.

The flat mirror (2) is a deflecting mirror to keep the beam in the space provided.

The convex mirror is made of plastic while the flat mirror is made of glass.

Fig. 40: Identifying Curved And Plane Mirrors On HUD

HUD MIRROR REFERENCE CHART

1. Curved mirror
2. Plane mirror

LED Array

There are two LED arrays. The LED array is an arrangement of LEDs in one plane and acts as the back lighting for the TFT projection display. The LED array generates the light required for the HUD brightness. The LED arrays consist of red and green LEDs. The LEDs generate the brightness of the HUD content as controlled by the master PCB.

PCB

The following components among others are incorporated on the PCB:

• K-CAN interface
• Processor (CPU)
• LVDS controller
• EEPROM memory
• Power supply

The video signals are passed on to the display by the instrument cluster via an LVDS lead.

Fig. 41: Identifying PCB

Housing

The casing is made of aluminum and consists of a bottom section and the plastic cover. The (aluminum) cooling fins and the electrical power supply are attached to the bottom section. The cover glass is integrated into the cover.

Fig. 42: Identifying Housing

Windshield

The windshield is a "special design" that is essential for projection of the displays. The outer and inner glass panes are bonded to a plastic film, just like in the standard windshield. Unlike in the standard windshield, this plastic film is not parallel but is tapered over the entire area of the windshield.

The taper prevents the HUD from displaying images twice. The taper tip points downwards and starts at a distance of approximately 10 cm to the bottom edge of the windshield.

The end of the taper 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 taper tip is 0.8 mm. The thickness of the end of the taper is 1 mm.

The total thickness of the bottom edge of the windshield is 4.5 mm. The total thickness of the top edge of the windshield is 4.7 mm.

Fig. 43: Identifying Plastic Film, Outer And Inner Glass Pane On Windshield

WINDSHIELD LEGENDS

1. Outer glass pane
2. Plastic film
3. Inner glass pane

mm - Unit of measurement in mm

Incorrect Windshield Fitted

The HUD image is always reflected on the windshield. These two images are overlaid by the angle of inner surface and outer surface of the taper in the HUD screen, so that the driver windshield only sees "one" image.

Fig. 44: Identifying Double Reflection On HUD Screen

WINDSHIELD REFLECTIONS REFERENCE CHART

1. Display
2. Outer surface of the windshield
3. Inner surface of the windshield
4. Reflection on the outer surface of the windshield
5. Reflection on the inner surface of the windshield
6.  

Because of the angle of tilt of the glass in a standard windshield, the two reflected images are offset against one another.

The illustration below shows the result when a Rain/light sensor standard windshield is fitted.

Fig. 45: Double Display By HUD

The rain and light sensor provides the brightness signal over the LIN bus to the roof function Center FZD and then to the K-CAN.

Eyebox

The eyebox 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 eyebox is roughly:

• 70 mm vertically plus +- 30 mm range of adjustment
• 130 mm horizontally.

The HUD image is not clearly visible outside the eyebox limits.

Fig. 46: Identifying Eyebox, Shift To Left/To Right Vision

LEFT/TO RIGHT VISION REFERENCE CHART

Fig. 47: Eyebox, Shift Upwards/Downwards Vision

UPWARDS/DOWNWARDS VISION REFERENCE CHART

Instrument Cluster

For the purposes of filtering the speed reading, a distinction is made between acceleration, braking and coasting phases.

When the car is in the coasting phase, 3 successive values are averaged and then the speed is updated.

Check Control Messages

All CC messages are also displayed on the HUD. The instrument cluster has the master function for the messages. The symbol together with the associated text is transmitted by the instrument cluster. CC messages are given precedence over the display of other information such as navigation-system directions, for instance.

NOTE: A Check Control message is displayed for 8 seconds. If several CC messages occur simultaneously, each one is displayed for 3 seconds.

Controls

The following controls are used in the operation of the HUD:

• ON/OFF button on the BEFAS
• Dimmer wheel in the light switch cluster
• Controller.

Driver Assistance System Control Panel

The HUD On/Off button is located on the BEFAS. The 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.

Fig. 48: Display ON/OFF Button On BEFAS

Instrument-lighting Dimming

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

Fig. 49: Instrument-Lighting Dimming Screen

Controller

The HUD brightness and height settings are adjusted with the Controller via the CID. Brightness setting is also termed brightness offset.

Functions such as e.g. navigation can also be set with the Controller in the Function selection menu. Therefore these settings have an indirect effect on the HUD display.

READ NEXT: