Frequently Asked Questions

Frequently Asked Questions

Q: What does the viewing angle of a display specify?

The viewing angle specifies the angle at which the display is best viewed from. Different viewing angles can affect apparent contrast and visibility of the screen. The viewing angle can depend on LCD fluid type and duty cycle.

Q:What is the temperature range of my display?

The temperature range is specified for each display and can range from normal, wide to ultra-wide. The specific temperature range of the display is listed as an operational temperature and storage temperature in the datasheet of the display. For example, the wide temperature range is from -20 to 70 ˚C.

Q: How is the brightness on a LCD module defined?

It is the average brightness measured from 9 surface areas of the display. The surface is divided into 9 equivalent partitions and the brightness is measured from center of each partition.

Q: What is cd/m^2?

It is the acronym of Candela per squared meter that represents the unit of brightness. Candela has another term of”nit”.

Q:What unit is display brightness measured in?

Display brightness is specified in terms of nits or candelas per square meter (cd/). This is the measurement of light emitted from the display per square meter. 1 cd/m2 is the brightness of an average candle.

Q:What is the difference between active area and viewing area?

The viewing area is the area of the glass on the display. The active area is the the area in which the pixels can be displayed.

Q:What is CGRAM?

CGRAM is an acronym that stands for “Character Generated RAM” which is a memory location provided by the display for character generation. This memory defines the available characters and has a small amount of memory for custom character generation for character LCDs.

Q:What is DDRAM?

DDRAM stands for “Display Data RAM” which is the memory location that references the pixels to be displayed. This memory location acts as a working data buffer for the display. The DDRAM controls which character/bitmap is displayed.

Q: How is the contrast ratio on a LCD module defined?

Contrast ratio (CR) =Brightness measured when LCD is at “white state”/Brightness measured when LCD is at “black state”

Q: How is the resolution on a LCD module defined?

It is the number of color pixels over the surface area of a LCD module. It is calculated by the numbers of pixels in the row and in the column.

Q: What is LCD response time?

Response time is the amount of time a pixel in a LCD takes to go from black to white and back to black again. It ismeasured in milliseconds (ms). Smaller values represent faster transitions and therefore smoother images.

Q:What is the refresh rate should I operate my display at?

The refresh rate is how often the display is refreshed per second in order to maintain an image. A display is typically refreshed, or redrawn, at a rate of 60 frames per second or 60 Hz.

Q:How is backlight power specified?

The backlight power is specified as the forward voltage and current applied across the entire backlight circuit not per LED. If the forward voltage and current is supplied to the anode and cathode pins of the backlight the LEDs will turn on.

Q: What do the RGB bits represent?

There are three colors, red, green and blue, in a pixel. The changes of the saturation level of each color combine intoa spectrum of colors. The saturation level can be represented by bit. The number of bits represents the power to 2.For example, if there are 8 bits for red, then there are 256 levels of saturation. Therefore, when we have 24 bits in a LCD module for color representations, 8 bits are equally divided to red, green and blue. In this way, there can be 16.8 millions colors.

Q: What is TFT?

TFT-LCD stands for thin-film transistor liquid-crystal display.It uses liquid crystal between to glass substrates to control the passage of light. The color filter is on the front glass substrate, and the back glass substrate has transistors on it. When voltage is applied, the liquid crystal is bent and a pixel is formed by the light that passes through. The color filter on the front glass substrate gives each pixel its own color. The combination of these pixels in different colors forms the image on the panel.

Q: What is an IPS display?

IPS stands for “In Plane Switching” which is a display technology that differs from TN, VA and OLED. IPS displays have features such as improved contrast, wide viewing angles, faster response times and higher color consistency.

Q: What does it mean for a transmissive display to be “normally black” or “normally white”?

The normally black description refers to TN displays that block the backlight when the pixels are not in use. This means the display will have a default black screen. A normally white mode display allows the backlight to shine through the TN and will have a default white screen.

Q: What is OLED?

OLED stands for Organic Light Emitting Diode. It is a light-emitting diode (LED) whose emissive electroluminescent layer is composed of a film of organic compounds that emit light when an electric current passes through it. This layer of organic semiconductor material is formed between two electrodes, where at least one of the electrodes is transparent.