DLP3030-Q1 based PGUs must be calibrated in order to ensure that the color point of the HUD is maintained across its operating conditions, which include a 5000:1 dimming ratio and –40°C to 105°C operating temperature. Additionally, the HUD must be calibrated to achieve smooth dimming, meaning the output brightness of the system should change linearly with the input brightness as in Figure 1-1.

Figure 1-1 Backlight Value vs PGU Brightness

White point of a PGU determines the ratio of red, green, and blue for a desired output. The target white point is specified as an x,y coordinate pair in the CIE 1931 color space chromaticity diagram shown in Figure 1-2. The wavelength of light output from the LEDs changes as the junction temperature changes, so calibration is required to compensate for these shifts. Additionally, a tolerance is limit is provided on the x and y coordinates. The calibration procedure makes sure that the white point of the DLP HUD EVM stays within the tolerance as the input brightness level, referred to as backlight value, is adjusted.

Figure 1-2 CIE 1931 Color Space Chromaticity Diagram

The overall goal of the PGU calibration process is to generate a unique calibration file to be paired with each production PGU manufactured. This calibration file stores a series of look-up tables, each mapped to a different temperature, that are used by the Piccolo software to map input backlight values to system parameters. This calibration file will maintain an accurate color point for all brightness levels across temperature.

These calibration steps are completed using the following tools.

• Color Analyzer
• Neutral Density Filters
• Diffuser Screen
• USB to SPI Converter

The DLPC120 Automotive Control Program is configured to work with the Konica Minolta® CA-210, Total Phase®Cheetah™ SPI Host Adapter, and a Windows PC. See Section 3 for more details.