28.1: Invited Paper: What’s the Focus of Debate in IEC Standardization for the Measurement of Laser Projection Displays?

Abstract

The projection displays which use lasers or laser hybrids as light sources have been widely applied in offices, homes, and theaters. The optical performance has been more enhanced recently with the development of the technologies, especially in light enhancement, color reproduction, luminance contrast, and dynamic range. The characterization and measurement for these projection displays become very important.The full‐frame projection technologies such as digital micromirror devices (DMDs), liquid crystal on silicon (LCOS), and liquid crystal display (LCD) projectors are typically concerned in the international standardization. The image quality of the projection system in graphics and video reproduction has been discussed in IEC WG10 “Working group of Laser Displays.“ In recent years, the IS (international standard)‐ IEC62906‐5‐1 Laser display and devices Part 5‐1 Measurement of Optical Performance for Laser Front Projection has been developed and reached the CDV stage. However, at this stage, there are some discussions among the expert’s group on the issues of the optical measurement method. The main issues are the two topics related to the CLO (Color Light Output) and CGV (Color Gamut Volume). There are two opposing views within the working group which is a very challenging topic. According to IEC/ISO rule, the consensus is difficult to be achieved for more 2/3 favor support and less 1/4 against.In the traditional projectors, due to the graphic display is mainly used for black and white usage in the office application, the luminous flux output of the full white field was used as the primary indicator in the specification of the standard product. The light output is directly dependent on the power of the projection source. Therefore, a white light enhancement method is employed in some projection display technologies, and in such cases, the brightness of a color display is often lacking. However, this is no longer the general case. Manufacturer use different ways to boost the white lumen value for the full white screen, but the saturated colors do not get the same boost in brightness. The lumen ratio between the full white and the colors is no longer maintained. In the new standard we recommend using a regional grid pattern to test the projector's light output, including white light output and color light output.Set of four colour tile test patterns used for projector characterizationfigureMoreover, the argue for color volume method is the derivative from the CLO/WLO issue. The main point is the argument between the applicability of CGV method (CIELAB usage) in HDR/SDR conditions. In this paper, we reviewed some of the most important aspects to provide a basic understanding the current development of laser projection display measurement in IEC standardization.Example of range in colors produced by a given display as represented by the CIELAB color spacefigure