Capacitive Touch Screen Placement on Color Filter Substrate
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Solution Overview
Problem
Existing liquid crystal display devices with touch screens face issues such as the tearing of the protection layer and conductive layer due to frequent use, leading to functionality loss, and suffer from deteriorated image contrast due to the backlight configuration, where light falls on the touch screen side instead of the regular viewing side.
Innovation Solution
A capacitive touch screen is installed on the color filter substrate side of the liquid crystal display panel, sharing the same flexible wiring substrate with the liquid crystal display panel, with the connection portions formed on the interior side to reduce component count and enhance reliability, and the backlight is placed at the rear of the TFT substrate to maintain image contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the touch screen is placed on the TFT substrate side with the backlight, then the device structure is simplified, but the image contrast deteriorates and the conductive layer tears due to frequent touching
Solution Approach 1:
The patent inverts the conventional touch screen placement by positioning it on the color filter substrate side instead of the TFT substrate side. This inversion resolves the contradiction by protecting the conductive layer from direct touching (improving reliability) while maintaining proper light transmission path for image contrast, and the color filter substrate provides structural support.
2Quantity of substance
If the same flexible wiring substrate is shared for both touch screen and liquid crystal display panel, then component cost is reduced, but connection reliability decreases due to increased complexity
Solution Approach 1:
The patent merges the flexible wiring substrate for the touch screen with the flexible wiring substrate for the liquid crystal display panel into a single integrated substrate. This combining reduces component count and assembly complexity while maintaining connection reliability through proper routing and connection design.
3Volume of moving object
If the flexible wiring substrate is folded back to reduce overall size, then device compactness is improved, but the connection portions become more vulnerable to damage
Solution Approach 1:
The patent implements a folded configuration where the flexible wiring substrate is nested back onto itself, with connection portions positioned in protected interior regions. This nesting approach reduces overall device volume while shielding vulnerable connection areas from external damage.
Data Source
AI summary
To realize an increase in an image quality of a liquid crystal display device having a capacitive touch screen, and an increase in are liability of a contact surface and a connection portion. A capacitive touch screen 50 and a liquid crystal display panel 30 are connected, by the same flexible wiring substrate 70, on an interior side when the touch screen 50 and the liquid crystal display panel 30 are laid one on top of the other. By so doing, a terminal is protected from an exterior, and an increase in a number of components is suppressed. Also, by installing the capacitive touch screen 50 on a color filter substrate 20 side of the liquid crystal display panel 30, a reduction of a contrast is prevented. Furthermore, a capacitive touch screen substrate 51 side is made a contact surface for an input. By so doing, a conductive layer 52 of the capacitive touch screen 50 is prevented from tearing due to an abrasion caused by a contact.