lcd display driver circuit in stock

A wide variety of lcd display circuit options are available to you, You can also choose from original manufacturer, odm and agency lcd display circuit,As well as from tft, ips, and standard.

Liquid Crystal Displays (LCD) is a technology that does not emit light, it only controls how an external light source passes through. This external light source could be the available ambient light, in the reflective display type, or the light from a backlight led or lamp, in transmissive display type. LCDs are constructed with two plates of glass (upper and bottom), a thin layer of liquid crystal (LC) between them and two light polarizers (Application Note AN-001 – Basics of LCD Technology, Hitachi, Application Note AN-005 – Display Modes, Hitachi).The polarizer is a light filter for the light electromagnetic field. Only the light components in the right electromagnetic field direction pass through the polarizer, while the other components are blocked.

The liquid crystal is an organic material that rotates the electromagnetic field of the light 90 degrees or more. However, when an electrical field is applied to the LC it does not rotate the light anymore. With the addition of transparent electrodes in the upper and bottom display glass, its possible to control when the light passes through, and when not, with an external source of the electrical field. Figure 1 (see Application Note AN-001 – Basics of LCD Technology, Hitachi) above illustrates this operation control. In Figure 1, the display is dark when there isn’t an electrical field. This is because both polarizers filter the light in the same direction. If the polarizers are orthogonal, then the display will be dark when the electrical field is present. This is the most common situation for reflective displays.

The minimum electrical field, or voltage, to control the LCD is called the ON threshold. The LC is only affected by the voltage, and there is hardly any current in LC material. The electrodes in LCD forms a small capacitance and this is the only load for a driver. This is the reason for an LCD being a low power device to show visual information.

However, its important to note that the LCD can’t operate with a direct current (DC) voltage source for too long. The application of a DC voltage will cause chemical reactions in LC material, permanently damaging it (Application Note AN-001 – Basics of LCD Technology, Hitachi). The solution is to apply an alternate voltage (AC) in LCDs electrodes.

In static LCDs, a backplane electrode is built in one glass and individual LCD’s segments, or pixels, are put in the other glass. This is one of the simplest LCD types and the one with the best contrast ratio. However, this type of display usually requires too many pins to control each individual segment.

In general, a driver controller sources a square wave clock signal for the backplane and a clock signal for the segments in the front plane together. When the backplane clock is in-phase with the segment clock, the root-mean-square (RMS) voltage between both planes is zero, and the segment is transparent. Otherwise, if the RMS voltage is higher than LCD ON threshold, the segment becomes dark. The waveforms for the backplane, on and off segment are shown in Figure 2. As can be seen in the figure, the ON segment is out-of-phase in relation to the backplane signal. The off segment is in-phase in relation to the backplane signal. The applied voltage could be between 3 and 5 volts for low cost, low power displays.

The clock signal for LCD’s backplane and segments usually are in the range of 30 to 100 Hz, the minimum frequency to avoid a visual flicker effect on LCD. Higher frequencies are avoided to reduce the power consumption of the overall system. The system composed of LCD and drivers would consume little current, in the order of microamperes. This makes them perfectly suitable for low power and battery power supply source applications.

In the following sections, the design of an LCD static driver with GreenPAK device that can generate the backplane clock signal and the individual segment clock signal for a commercial LCD is presented in detail.

The new line of 3.5” TFT displays with IPS technology is now available! Three touchscreen options are available: capacitive, resistive, or without a touchscreen.

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