Frequently Asked Questions

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Yes, CEVIANS can offer custom displays in the form of a modified COTS display to meet a specific requirement. This typically includes a custom mechanical design that will change the outline of the COTS display assembly. These changes include a high-brightness or dual mode backlight unit designed for rugged applications. Also, CEVIANS Displays has the ability to offer a fully customized cell and interface design to meet specific requirements.

A dual mode backlight is a term given to a display that has two separate backlight systems in one display module. Typically, there is a high-brightness LCD backlight system used to view the LCD in high ambient conditions also known as sun light readable. The second backlight system is used in dark environments when viewing the LCD in an environment that requires the light to be filtered in order to meet the lighting requirements of MIL-STD-3009. These backlights are operated independently of each other and are controlled by the user of the display device.

The ability to read an image element that is displayed as characters, symbols, or video image patterns in direct sunlight or high ambient lighting conditions. These images must be recognizable to an observer of the display by improving the contrast ratio of the image on the display. In an application where a COTS display is used, this is accomplished by increasing the brightness of the backlight unit to transmit light through the LCD, and optimizing the display's optical system to minimize all combined reflections. When designed as a complete system it is possible to maximize display efficiency so that all optical components, EMI filters, heaters, touch panels, and bonding agents shall be readable in bright ambient conditions.

TFT (Thin Film Transistor) LCD (Liquid Crystal Display) - These types of display screens are today's most commonly used, and are available in a wide range of shapes, sizes, resolutions, and interfaces. This type of technology is typically a full color display, and because of the active transistor matrix used to control the liquid crystal element this technology is sometimes referred to as AMLCD (Active Matrix Liquid Crystal Display).

Liquid Crystals are made up of a substance that can be controlled by external electric charges to bend and refract light waves as they pass through the crystal materials. Manipulation of the properties of this light through a color filter creates the various shades of color and shadow you see on the display.

The higher the contrast ratio of an image the easier it is for the human eye to see the image. Contrast ratio is defined as the ratio of the brightness of a white image in comparison to the brightness of a black image. Typical measurement of CR for a Liquid Crystal Display would be: Contrast Ratio (CR) = Brightness at the screen center when all pixels are "white" / Brightness at the screen center when all pixels are "black"

Luminance uniformity is typically a measurement of uniformity of color and white on the display. This measurement requires that a device for measuring the intensity of light be positioned at least five points (typically nine points) on the screen surface. The measurement locations include the center point plus four (or eight) peripheral points that are always 10% of the screen width from the sides and 10% of the screen height from the top and bottom.

The points are tested and the data recorded as luminance (L):
Uniformity = (Lmax / Lmin).
Non-Uniformity = 100% [1 - (Lmin / Lmax)].
Luminance Variation = (Lmax / Lmin).
Luminance % Uniformity = 100% [(Lmax - Lmin) / Lmax].

The viewing angle is the maximum angle at which a display can be viewed with acceptable visual performance. Measured in contrast ratio - viewing angle is the point where contrast ratio equals or exceeds a fixed value. Typically, this value is at the point where the contrast is </= 10:1. The viewing angle is controlled by the technology used to manufacture the LCD. Currently, there are four different TFT LCD technologies in the market. These technologies differ in construction, alignment, and control methods of the liquid crystal materials that directly affect viewing angle. These technologies are TN+Film, VA, IPS, and FFS.

The Four LCD Technologies Defined

1. TN + Film (Twisted Nematic + Film Compensation) - This technology is used for entry-level and mid-range solutions, very common in consumer and industrial applications. The TN + Flim product is known for its simple manufacturing process, high-transmittance, and good response rate.
2. VA (Vertical Alignment) - This is used for mid to top-range solutions like consumer TVs, high-end monitors, and industrial applications. This type of LCD is known for high-transmittance and very fast response rate needed for video applications.
3. IPS (In Plane Switching) is used for high-end solutions and industrial medical applications. This technology is known for high color stability and a simple manufacturing process.
4. FFS (Fringe Field Switching) - This technology is used for high-end solutions and has one of the widest viewing cones. This technology is known for the highest transmittance, wide viewing angle, authentic color, and is used in a number of handheld applications.