First. Parameter Definition
The nominal value of industrial display contrast refers to the maximum brightness to minimum brightness ratio (such as 1000:1) measured by the manufacturer under ideal laboratory conditions. Measured value refers to the dynamic range data obtained by the user through the spectrochromatograph under actual working conditions. The core difficulty lies in the manufacturer’s test is often used static screen (all black / all white) and constant ambient temperature, while the actual application scenarios there are dynamic image switching and temperature fluctuations, resulting in a delay in the response of the liquid crystal molecules, the measured contrast ratio is generally reduced by 10-25%. Daily application will appear, for equipment status monitoring of industrial panels nominal 1500:1, measured in the workshop 50 ℃ environment down to 1120:1 this situation.
Second, the nominal value of the technical realization of the principle
In order to achieve the nominal value, its high nominal contrast ratio is usually realized by area dimming technology. The backlight module is divided into independent control blocks (usually 128-256 zones), in the display of dark images when the LED lamp beads are partially turned off. However, this technology suffers from halo effect defects, and in precision scenarios such as medical image display, a luminance penetration band of 0.5-1mm is prone to appear at the edge of the CT image. Therefore, the solution in the field of automobile manufacturing is to use global dimming + optical compensation film, this method will sacrifice the nominal contrast ratio (maintaining 800:1) in exchange for picture uniformity.
Third, the impact of the measured value
In the bright light environment and outdoor construction machinery in the industrial display, the difference in measured contrast ratio will directly affect the readability. For example, the port crane console monitor nominal 2000:1, but in the midday sunshine measured only 420:1, however, by increasing the quantum dot film can be measured to 680:1. In addition, the medical field also has a certain impact, so the medical field requirements are more stringent, the DICOM standard specifies that radiology diagnostic monitors must be measured contrast ratio ≥ 650:1.
Fourth, industry application standards
In the field of industrial displays, industrial consoles can generally accept parameter deviations of 30% or less, but there are mandatory specifications for special areas, such as avionics need to comply with the DO-160G standard, which requires a contrast retention rate of ≥85% within the temperature range of -55℃ to +85℃; petrochemical explosion-proof displays to implement the ATEX/IECEx certification, which prohibits the use of active heat dissipation components, and the measured contrast ratio The measured industrial display contrast ratio needs to be stabilized at ±15% of the nominal value.
Fifth. Solutions
Procurement can require manufacturers to provide industrial display contrast third-party test reports (such as TÜV or UL certification data), need to focus on 25%, 50%, 75% brightness level of the measured contrast curve. On-site verification can be used X-Rite i1Pro 3 spectrophotometer, in the typical operating temperature of the equipment to measure 10%, 50%, 90% gray-scale transition performance. Semiconductor cleanroom through the installation of ambient light sensors to achieve real-time dynamic compensation of the display contrast, can be improved by 40% of the picture stability.
Golden Margins –Entire Range of Touchscreen Products
We hope you found these touchscreen or panel PC fundamentals informative. Goldenmargins offers a broad selection of Industrial Touchscreen Monitors and Touch Panel PCs in various sizes and configurations, including medical touch screens, sunlight-readable touch screens, open-frame touch screens, and waterproof touch panels, as well as other unique touch screen or panel PC designs. You can learn more about our services HERE or by calling us at +86 755 23191996 or sales@goldenmargins.com
