Liquid Crystal Display Apparatus with Simultaneous Optical Input Detection
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Solution Overview
Problem
Conventional liquid crystal display apparatuses require temporary cessation of image display for reading input information, such as fingerprints or documents, due to the need to switch from a display video to a read video, which can take several seconds and disrupts image information output.
Innovation Solution
A liquid crystal display apparatus with a control unit that manages both display and read operations within a frame period, utilizing a backlight that can blink and optical input devices integrated with scanning lines, allowing simultaneous image display and input detection by dividing the frame period into segments for external light and reflected light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the display video is changed to a read video for optical input detection, then the input information can be read, but the display of image information is stopped temporarily
Solution Approach 1:
The patent divides the frame period into multiple time slots: a first time slot for external light detection and a second time slot for reflected light detection. This segmentation allows different detection modes to occur at different times without interrupting the overall display operation, resolving the contradiction between achieving accurate optical input detection and maintaining continuous image display.
Solution Approach 2:
The patent implements periodic detection cycles where external light detection and reflected light detection are performed in alternating time slots within each frame period. This periodic action enables continuous operation of both display and detection functions, eliminating the need for temporary display cessation while maintaining detection accuracy.
2Measurement precision
If the read video is displayed uniformly in a single color to avoid affecting reading, then the optical input can be read accurately, but the display screen cannot show the original display video
Solution Approach 1:
The patent segments the frame period into distinct time slots where read video display and original display video are shown at different times. During the first time slot, a read video with uniform color is displayed for external light detection, while during the second time slot, the original display video is restored for reflected light detection. This temporal segmentation preserves both detection accuracy and display information without permanent loss.
Solution Approach 2:
The patent performs preliminary detection using external light during the first time slot before displaying the original video content during the second time slot. This preliminary action allows the system to capture input information in advance while maintaining the ability to display the original video content subsequently, preventing information loss.
3Measurement precision
If the display screen is changed to a read screen for several seconds to read an image, then the input information can be read, but the image information display is stopped in this time
Solution Approach 1:
The patent implements a periodic detection scheme where external light detection and reflected light detection are performed in alternating time slots within each frame period. This periodic action enables continuous operation of both display and detection functions at high speed, eliminating the need for several-second interruptions and maintaining display productivity.
Solution Approach 2:
The patent ensures continuous useful action by performing optical input detection during brief time slots within the frame period without completely stopping the display operation. The display continues to function throughout, with detection operations interleaved in a continuous cycle, maintaining both productivity and detection capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous image display while allowing for accurate and simultaneous input detection, improving user experience by preventing interruptions and enhancing detection accuracy through logical operations on detection images.
Implementation Method 1
light from a light source such as a backlight BL is temporarily irradiated onto a document or the like on the liquid crystal display panel via the displayed read video. Then, light reflected from the document or the like is detected within the liquid crystal display panel
Data Source
AI summary
A liquid crystal display apparatus includes a display panel configured to have a plurality of scanning lines for which liquid crystal display elements each containing an optical input device and a display pixel are arranged, respectively, a backlight configured to be arranged facing the display panel to illuminate the display panel, and a control part configured to control writing into the display pixel and reading of a detection signal of the optical input device, wherein the control part displays an external light detection image substantially shielding light from the backlight on the display pixels throughout a first period of a frame period, and displays a display image on the display pixels throughout a second period of the frame period.