3 touch technologies of LCD capacitive touch screen In-Cell On-Cell OGS

OGS (One Glass Solution) is currently the primary solution used in fully laminated LCD capacitive touch screens. It integrates the touch layer and protective glass layer together by coating the inner side of the protective glass with ITO (indium tin oxide) conductive layer and then directly coating and lithographing on the protective glass. This saves a piece of glass and a bonding process, making the LCD touchscreen thinner and lighter while reducing costs. However, because the OGS protective glass and touch screen are integrated, it usually needs to be strengthened first, then coated and etched, and finally cut. Cutting on strengthened glass is challenging, and it may cause some fine cracks on the glass edge, which can weaken the strength of the glass.

This method embeds touch panel functionality into the LCD pixels by incorporating touch sensors into the display panel. The In-cell places the ITO touch film under the upper glass substrate of the display panel and fuses it with the liquid crystal layer. The innovation of the In-cell touch panel lies in the addition of circuits to the liquid crystal, enabling the traditional touch screen's sensing and touch input capabilities. The In-cell touch panel is not only more accurate but also eliminates the need for a separate touch panel, making the entire touch screen thinner and lighter. Traditional touch screens are often challenging to read under sunlight due to parallax, but the In-cell technology eliminates this issue, improving readability.

This solution embeds the touch screen between the color filter substrate and polarizer of the display panel, adding touch sensors to the LCD panel. It is technically easier than In-cell and is currently mostly used in Samsung AMOLED panel products. However, it has yet to overcome the challenge of thinning and may result in color unevenness during touch.