What Is a Head-Up Display?
Head-up displays are displays located in front of the windshield or instrument hood.
It is characterized by its ability to project vehicle speed and car navigation information. Since the necessary information is displayed in a limited space, it is believed to reduce driving fatigue by reducing the need to shift one’s viewpoint.
Although head-up displays are still in their infancy, they have been adopted in many cars in recent years. It is also a component that may be sold separately and can be retrofitted.
Uses of Head-Up Displays
Head-up displays are used to project information necessary for driving in the driver’s line of sight. The main information displayed in head-up displays includes speed, navigation information, and fuel level.
Usually, the navigation system can be placed between the driver’s seat and the passenger’s seat. However, when the information is projected on the head-up displays, there is no need to remove one’s eyes from the car. Therefore, it is expected to become more widely used from the standpoint of preventing people from looking away from the car.
Principle of Head-Up Displays
Head-up displays are transmissive displays. In order to project the image transparently, a device is used to project the image.
When a portion of the windshield is used for head-up displays, mirrors are used instead of projecting information directly onto the windshield. The display unit that shows the necessary information is located in the dashboard, and the image projected from the display unit is magnified by a diffuser or magnifying glass, and what is projected onto the windshield is the reflected image.
At this time, the light path through which the image is actually projected and the light path perceived by the driver overlap, making the image appear to be reflected on the windshield. Because of this principle, areas other than those shown on the head-up displays appear transparent, the use of head-up displays reduces eye movement while driving.
Types of Head-Up Displays
In projection-type head-up displays, a translucent screen appears on a special display and shows information.
There is also a smartphone display type that projects a smartphone screen onto the display. Thus, the navigation system can be used without shifting the eyes to the smartphone. The smartphone is placed on the head-up displays device and information is obtained by reflecting it back. In other cases, the head-up displays device and the smartphone are connected via Wi-Fi to project information.
The irradiation type can project information onto the windshield. Images can be projected from the head-up displays and displayed directly on the windshield.
How to Select Head-Up Displays
There are two types of head-up displays: those that are connected to the vehicle failure diagnosis system installed in the vehicle and those that are linked to a smartphone. When using a vehicle diagnostic system, a cord connects the connector to the head-up displays, and if equipped with GPS, the display can be powered by USB and can use some functions.
For head-up displays that are connected to a smartphone, the basic functionality depends on the application. For the type with a reflective smartphone screen, the projected screen is inverted, so the smartphone screen must be inverted to display. When connected via wired or Bluetooth, Android Auto and Apple CarPlay can be used.
Structure of Head-Up Displays
The head-up displays can be connected to the car using a cigarette lighter socket or an on-board diagnostic monitoring device, like a car charger with a USB terminal, which provides electricity when connected to the car’s on-board cigarette lighter socket and can be easily disconnected. Onboard diagnostic equipment provides a steady supply of power and uninterrupted meter functionality. However, in-vehicle diagnostic equipment is difficult to remove.