A liquid crystal writing device and method for realizing partial erasing by using light

Abstract

The invention discloses a liquid crystal writing device and method for realizing partial erasing by using light, comprising: a conductive layer, a bistable liquid crystal layer and a base layer arranged in sequence; the base layer is integrated with: a plurality of erasing devices arranged in an array Each erasing unit is provided with an erasing electrode and a thin film field effect transistor TFT connected to the erasing electrode; at least one first wire for supplying each TFT control voltage; for supplying each TFT input voltage at least one second wire; the thin film field effect transistor TFT is configured to be turned on after receiving light with a set intensity in a critical cut-off state, so as to input a set voltage to the corresponding erasing electrode, so that The erasing electric field is formed at the overlapping position of the erasing electrode and the conductive layer to realize local erasing. The invention utilizes the phenomenon of TFT light sensitivity to realize partial erasing of the liquid crystal writing board; no positioning circuit and voltage selection circuit are required, the circuit structure of the product is simplified, and the reliability is improved.

Description

technical field [0001] The invention relates to the technical field of liquid crystal writing boards, in particular to a liquid crystal writing device and method for realizing partial erasing by using light. Background technique [0002] The working principle of the liquid crystal writing board currently on the market is to use the bistable property of the liquid crystal to display and / or erase the written content on the liquid crystal writing board. Taking cholesteric liquid crystal as an example, the writing pressure track of the writing pen is recorded by changing the liquid crystal state at the tip of the pen by the pressure acting on the liquid crystal writing board, and then the corresponding writing content is displayed; the structure of the cholesteric liquid crystal is changed by applying an electric field, Thereby, the writing track on the liquid crystal writing board disappears to realize erasing. [0003] The technical solution disclosed in the prior art to achi...

AI Technical Summary

Problems solved by technology

refer to figure 1 , when illuminated, due to the generation of photogenerated carriers, the conductivity of the active layer changes, that is, the phenomenon of photoconductivity occurs, the on and off currents of TFT will increase compared with those without light, and the threshold voltage will also occur Corresponding changes; in the prior art, when the TFT process is applied to the field of liquid crystal display, the TFT is directly exposed to the illumination of the backlight source, and due to the influence of the photoconductive effect, the threshold voltage and the "on / off" current ratio of the TFT will occur. Changes affect the display effect; therefore, in liquid crystal displays, the switching element TFT is usually subjected to light-shielding treatment to avoid the influence of light on the display effect

[0007] The prior art discloses a technical scheme in which light-emitting elements are arranged on the writing pen, and the light-sensitive characteristics of the thin film transistor TFT are used to realize optical writing display on the electrophoretic display; however, the purpose is to realize writing display, improve writing delay, and cannot realize local wiping Moreover, this solution needs to add a filter layer during processing to only allow light of a specific wavelength (such as: red light) to pass through; increasing the complexity of the design and production costs

Images