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Measuring of the Basic Parameters of LCD Displays

Barczyk R., Kabzinski B., Jasinska-Choromanska D., Stienss A.

Journal of Automation Mobile Robotics and Intelligent Systems

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2012

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Vol. 6, No. 1

46-48

EN

This article is about realization of the laboratory stand used for measuring parameters of LCD displays. The stand together with additional accessories (spectrophotometer and measuring probes) as well as software allow to measure a wide range of parameters (colour gamut, response time, contrast coefficient and its irregularity, luminance of black colour and its irregularity, luminance of white colour and its irregularity, changes of luminance depending on the viewing angle). This paper also show method and results of measurements of differences in contrast ratio and luminance uniformity between particular pieces of the same model of a display screen (research has been carried out on 5 pieces of the same model of a display). The presented results show that the measured value of the viewing angle may significantly differ from the value provided by producers of displays.

2

Projekt stanowiska badawczego do pomiarów pionowych i poziomych kątów widzenia monitorów LCD

Barczyk R., Jasińska-Choromańska D, Kabziński B., Stienss A.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 9

981-984

PL

W artykule przedstawiono projekt oraz realizację stanowiska pomiarowego służącego do pomiarów kątów patrzenia monitorów LCD. Przedstawione zostały założenia, które przyjęto na etapie projektu, zgodność z normami ISO oraz przykładowe wyniki pomiarów. Przedstawione wyniki pomiarów pokazują, że zmierzona wartość kąta patrzenia może się znacznie różnić od wartości podawanej przez producenta monitora.

EN

The paper deals with project and realization of a laboratory stand for measuring viewing angles of LCD displays. There is a need to build such stands in order to check whether the parameters of displays reflect the ones provided by their producers. The ISO norms guidelines as regards tests of displays (ISO 9241-303:2008 "Ergonomics of human-system interaction - Part 303: Requirements for electronic visual displays" and ISO 9241-305:2008 "Ergonomics of human-system interaction - Part 305: Optical laboratory test methods for electronic visual displays") were used to make sure that the results of such research were reliable. The stand together with additional accessories (spectrophotometer and measuring probes) as well as software allow measuring a wide range of parameters (colour gamut, response time, contrast coefficient and its irregularity, luminance of black colour and its irregularity, luminance of white colour and its irregularity, changes of luminance depending on the viewing angle). In this paper there is described the stand construction as well as the method for measuring the luminance change depending on the viewing angles, which is one of the most important parameters in the situation when there are several people looking at a certain screen. The presented measurement results also show differences between particular pieces of the same model of a display screen (investigations were performed on 5 pieces of the same model of a display). The presented results show that the measured value of the viewing angle may significantly differ from the value provided by producers of displays.

3

Pomiary równomierności oświetlenia matryc LCD

Barczyk R., Kabziński B., Jasińska-Choromańska D, Stienss A.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 11

1355-1358

PL

Artykuł porusza kwestie pomiaru równomierności oświetlenia oraz parametrów związanych z tym zjawiskiem: współczynnika kontrastowości, nierównomierności kontrastu, luminancji i jej nierównomierności. Przedstawia powody, dla których te parametry są istotne pod względem użytkowym, oraz opisuje metody, jakimi można badać wymienione powyżej parametry. Przedstawia wyniki badań wykonanych na próbie pięciu monitorów tego samego modelu.

EN

The illumination uniformity in LCD monitors is analyzed in the paper. The phenomenon is described and explained by taking into consideration the following parameters: contrast ratio, luminance, uniformity of display contrast, and luminance. No defined measurement method of these values exists (except partially different standards by ISO, VESA, ANSI). The method which unify and minimize measurements is described in the paper. The same measurement points are used to measure all parameters under consideration. Luminance measurements are made in a dark room, on center of a screen surface emitting white color. The same is also used in uniformity measurement (Eq. 1). It describes luminosity difference values in different places of monitor. Contrast ratio (Eq. 2) measurements were made using electronic set of photodiode and transimpedance amplifier in one structure (Fig. 2). Uniformity measurement of display contrast have been made in few points, defined by VESA organization (Figs. 3, 4, 5, 6). 5 monitors of the same model were tested (Tab. 1). Contrast ratio show significant difference for each monitor and between each other. Similar results are for luminance and luminance uniformity (Tab. 4) where difference in uniformity reached almost 40%. Type of monitor backlight is main cause of poor uniformity, but also quality of LCD matrices may have influence on overall comfort of using such moni-tors. The results show that luminance and contrast uniformity should be given in technical specification of products.