‘Black-to-Black’ and ‘Gray-to-Gray’ response times
The current ISO standard uses the ‘Black-to-Black’ response time, which measures how
many milliseconds a pixel requires to go from black to white and back to black again.
However, this information only has limited relevance. In practice, colour-intensive
films and action games hardly contain black-to-white changes. New panels, designed to
have optimum ‘Gray-to Gray’ pixel response times, fulfil the requirements for such ap-
plications. Currently a new standard is therefore being established, which entails an in-
dication of the ‘Gray-to-Gray’ response time in milliseconds. This measures how long a
pixel requires to pass through different shades of gray.
Technologies
Advanced Motion Accelerator
For applications such as films and computer games, fast pixel response times are the
most important variable (see ‘Response time’ for more information). Advanced Mo-
tion Accelerator (AMA) technology provides fast response times. By improving the
liquid properties of the liquid crystals and optimising the electronic systems, pixels can
quickly attain the desired position. The intelligent and dynamic AMA function doesn’t
only use a simple overdrive of the electrical voltage like conventional systems. The im-
age signal is analysed in real time and then controlled with an optimum voltage us-
ing the AMA circuit. This has the advantage of achieving precisely the desired colour
value, without overloading the pixels. These technologies are offered exclusively by AU
Optronics, a subsidiary of BenQ.
Senseye® technology
BenQ Senseye® technology provides dynamic optimisation of image quality. Unlike con-
ventional image processing, Senseye® separates the incoming colour signals in order to
adjust each colour individually. The result is a perfect image. Along with colour bril-
liance, Senseye® optimises brightness, the contrast ratio and image sharpness. Senseye®
also offers optimum user-friendliness. The user can select a pre-set mode for the desired
application (e.g. movies or gaming) and the Senseye® technology adjusts all other set-
tings automatically. At BenQ, we are permanently working on further developments of
Senseye® technology for improving image quality.
New Senseye®+photo technology, therefore, offers an additional sRGB colour mode,
which precisely adjusts colour temperature and the gamma value to suit the parameters
of the sRGB colour space. This ensures that the colours can consistently be reproduced
on different peripheral appliances (such as digital cameras and printers).
8 9
Modern LCD televisions operate with a wide format 16:9 HDTV resolution of
1,080 pixels (1,920 x 1,080). The first computer monitors with a screen diago-
nal of 24 inches and higher already support this resolution. This is important
because of the increasing convergence between IT hardware and traditional elec-
tronic entertainment systems.
Important LCD variables
Viewing angle
The viewing angle defines the monitor´s field of view. Technically, this value is deter-
mined by measuring the contrast ratio across the viewing field until it falls short of a
particular value – normally 10:1. Some companies use a benchmark value of 5:1, in order
to achieve better results. This doesn’t allow true comparison of values, as it is a deliber-
ate falsification. Certification in accordance with ISO 13406-2 offers clarification, as it
prescribes categorisation into viewing angle classes and the use of a defined measurement
procedure. Ergonomic requirements for the workplace define a minimum horizontal
viewing angle of 60°/60° (right/left) and a vertical viewing angle of 45°/45° (up/down). If
only two values are given for horizontal and vertical viewing angles, the values for right
and left and up and down respectively have been added together. In this case, for exam-
ple, a viewing angle of 120° horizontal and 90° vertical would be given.
Contrast ratio
The contrast ratio is the relationship between the brightness of the brightest and the
darkest pixels in an image. High contrast ratios improve legibility and ergonomic quali-
ties. A display should always achieve contrast values of 500:1. In this respect, liquid crystal
displays are significantly superior to conventional CRT displays, as a good CRT display
would only offer a ratio of 90:1.
Brightness
Brightness is the light emitted on a particular surface. Compared with conventional CRT
displays, LCD monitors offer superior brightness. CRT displays offer only approx. 80 to
100 cd/m² (candela per square metre), whilst values under 250 cd/m² for liquid crystal
monitors are considered unacceptable and are only found on outdated displays.
Response time
The response time is the time a TFT cell requires to change its colour. When pixel re-
sponse times are too long, some lower-performance displays produce ‘ghosting’ or
‘streaming’ effects on the screen when the image content is in motion. For standard
applications, maximum response times of 8 ms are sufficient. For applications with fast-
moving animations such as films, games and video editing, faster image formation is
required. The response time should not be more than 4 ms.
