24.2: A 1300‐dpi Optical Image Sensor Using an a‐Si:H Photo Diode Array Driven by LTPS TFTs

Abstract

We have developed a 1300-dpi optical image sensor using a hydrogenated amorphous silicon (a-Si:H) pin diode array driven by low-temperature polycrystalline silicon (LTPS) thin film transistors (TFT) on a glass substrate. This paper describes a new architecture for achieving a high-resolution optical image sensor using LTPS TFT production equipment.

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.…”

“…An optical sensor using an a-Si pin diode array driven by LTPS TFTs is shown in Figure 8. 34 These architectural features make it possible to obtain a high aperture ratio, high photosensitivity, and high pixel resolution. This technology points to the potential of large-area highresolution image sensors.…”

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.…”

P‐1: Self‐Modulated Amorphous Front and Back Light Sensors with Wide Dynamic Range

“…Some sensing functions using TFTs were already also demonstrated [2][3][4]. However, most of the conventional ambient light sensor systems were implemented by external discrete devices which cause additional cost and the design complexity.…”