Viewing angle
Encyclopedia
In display technology
parlance, viewing angle is the maximum angle
at which a display can be viewed with acceptable visual performance. In a technical context, this angular range is called viewing cone
defined by a multitude of viewing directions
.
The image may seem garbled, poorly saturated, of poor contrast
, blurry or too faint outside the stated viewing angle range, the exact mode of "failure" depends on the display type in question. For example, some projection screen
s reflect more light perpendicular to the screen and less light to the sides, making the screen appear much darker (and sometimes colors distorted) if the viewer is not in front of the screen. Many manufacturers of projection screens thus define the viewing angle as the angle at which the luminance
of the image
is exactly half of the maximum. With LCD screens, some manufacturers have opted to measure the contrast ratio, and report the viewing angle as the angle where the contrast ratio exceeds 5:1 or 10:1, giving minimally acceptable viewing conditions.
The viewing angle is measured from one direction to the opposite, giving a maximum of 180° for a flat, one-sided screen. Some display devices exhibit different behaviour in horizontal and vertical axis, requiring users and manufacturers to specify maximum usable viewing angles in both directions. Usually the screens are aligned and used to facilitate greater viewing angle in horizontal level, and smaller angle in the vertical level, should the two of them be different in magnitude.
Early LCDs had strikingly narrow viewing cone
s, a situation that has been improved with current technology.
Narrow viewing cone
s of some types of displays have also been used to bring a measure of security
in businesses, where employees handle private information in the presence of customers, banks being one example. Rectangular filters fitting to the computer monitors have also been sold as accessories for these kind of purposes.
Display device
A display device is an output device for presentation of information in visual or tactile form...
parlance, viewing angle is the maximum angle
Angle
In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...
at which a display can be viewed with acceptable visual performance. In a technical context, this angular range is called viewing cone
Viewing cone
-Viewing direction:When a visual display with non-vanishing size is seen by an observer, every point of the display area is seen from a different direction as illustrated in fig. 1. No two spots on the display are seen from the same direction...
defined by a multitude of viewing directions
Viewing cone
-Viewing direction:When a visual display with non-vanishing size is seen by an observer, every point of the display area is seen from a different direction as illustrated in fig. 1. No two spots on the display are seen from the same direction...
.
The image may seem garbled, poorly saturated, of poor contrast
Contrast ratio
The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color to that of the darkest color that the system is capable of producing...
, blurry or too faint outside the stated viewing angle range, the exact mode of "failure" depends on the display type in question. For example, some projection screen
Projection screen
A projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed, as in a movie theater; painted on the wall; or semi-permanent or mobile, as in a conference room...
s reflect more light perpendicular to the screen and less light to the sides, making the screen appear much darker (and sometimes colors distorted) if the viewer is not in front of the screen. Many manufacturers of projection screens thus define the viewing angle as the angle at which the luminance
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...
of the image
Image
An image is an artifact, for example a two-dimensional picture, that has a similar appearance to some subject—usually a physical object or a person.-Characteristics:...
is exactly half of the maximum. With LCD screens, some manufacturers have opted to measure the contrast ratio, and report the viewing angle as the angle where the contrast ratio exceeds 5:1 or 10:1, giving minimally acceptable viewing conditions.
The viewing angle is measured from one direction to the opposite, giving a maximum of 180° for a flat, one-sided screen. Some display devices exhibit different behaviour in horizontal and vertical axis, requiring users and manufacturers to specify maximum usable viewing angles in both directions. Usually the screens are aligned and used to facilitate greater viewing angle in horizontal level, and smaller angle in the vertical level, should the two of them be different in magnitude.
Early LCDs had strikingly narrow viewing cone
Viewing cone
-Viewing direction:When a visual display with non-vanishing size is seen by an observer, every point of the display area is seen from a different direction as illustrated in fig. 1. No two spots on the display are seen from the same direction...
s, a situation that has been improved with current technology.
Narrow viewing cone
Viewing cone
-Viewing direction:When a visual display with non-vanishing size is seen by an observer, every point of the display area is seen from a different direction as illustrated in fig. 1. No two spots on the display are seen from the same direction...
s of some types of displays have also been used to bring a measure of security
Security
Security is the degree of protection against danger, damage, loss, and crime. Security as a form of protection are structures and processes that provide or improve security as a condition. The Institute for Security and Open Methodologies in the OSSTMM 3 defines security as "a form of protection...
in businesses, where employees handle private information in the presence of customers, banks being one example. Rectangular filters fitting to the computer monitors have also been sold as accessories for these kind of purposes.