24.4: Optical Sensor Embedded Input Display Usable under High‐Ambient‐Light Conditions

Abstract

We have developed a new LCD having optical input function usable under high ambient-light conditions. Sensors having different sensitivities are dispersed in the panel, and a sensor driver circuit to control the sensor exposure time are formed monolithically in peripheral using LTPS technology. These two approaches contribute synergistically to widen the range of ambient light condition available for the input function.

Sensor applications of thin‐film devices originating in display technologies

“…Image sensors are other promising applications of the visible-light sensors. LTPS devices, [25][26][27][28][29][30] amorphous-Si (a-Si) devices, [31][32][33][34][35][36] and metal-oxide semiconductor devices 37 are utilized for the image sensors. The image sensors are used for image captures, fingerprint sensors, in-cell touch panels, pen inputs, three-dimensional (3D) sensing systems, etc.…”

Active‐matrix sensor in AMLCD detecting liquid‐crystal capacitance with LTPS‐TFT technology

“…The most popular in-cell touch-screen panel uses an optical-sensor method. [1][2][3][4][5][6] An optical sensor consisting of LTPS photodiodes detects finger shadows and light reflected from a backlight unit. This method realizes multi-touch and additional functionality as a contact image sensor and has led to new applications such as built-in scanner displays and built-in fingerprint-recognition displays.…”

Touch‐screen panel integrated into 12.1‐in. a‐Si:H TFT‐LCD

“…1 Recently, TSP displays have been developed as input devices for PDAs (personal digital assistants), hand-held phones, and tablet PCs. [1][2][3][4][5][6][7] The conventional TSP, which requires additional components to detect touch events, causes reduced contrast ratio and brightness and has resulted in thick modules. Therefore, various approaches to integrate the touch-screen function into the LCD panel have been reported, using an optical, [2][3][4] capacitive, and resistive sensor array.…”

“…[1][2][3][4][5][6][7] The conventional TSP, which requires additional components to detect touch events, causes reduced contrast ratio and brightness and has resulted in thick modules. Therefore, various approaches to integrate the touch-screen function into the LCD panel have been reported, using an optical, [2][3][4] capacitive, and resistive sensor array. [5][6][7] Most of the previous reports focus on an optical sensor array based on low-temperature poly-Si (LTPS) thin-film transistors (TFTs), which use the difference in the photocurrent between touching and not touching.…”