Booster Circuit with Threshold Compensation for Low-Voltage Displays
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Solution Overview
Problem
Miniaturized display devices for portable information devices face challenges in achieving low power consumption and reliable voltage boosting due to the limitations of existing booster circuits, particularly when formed on insulating substrates using thin film transistors, which suffer from irregular threshold values and reduced efficiency.
Innovation Solution
A booster circuit is designed with a simple channel structure and boosted capacitors that supply a voltage higher than the threshold voltage to the control terminal of switching elements, allowing for independent voltage boosting regardless of threshold values, and includes a diode connection mode to maintain reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a booster circuit is formed on a semiconductor substrate, then the booster circuit can be integrated with the driving circuit, but the threshold value irregularities and reduced boosting efficiency occur due to the high threshold values of switching elements formed by stacking
Solution Approach 1:
The patent divides the booster circuit into separate components: switching elements formed by stacking (for voltage boosting function) and driving circuit formed on semiconductor substrate (for control function). This segmentation allows each component to be optimized independently, resolving the contradiction between integration and performance.
Solution Approach 2:
The patent introduces an insulating substrate as an intermediary carrier that holds both the switching elements and driving circuit. This intermediary structure enables the booster circuit to be formed separately from the semiconductor substrate while maintaining functional integration, thus avoiding threshold value irregularities while achieving compact mounting.
2Area of stationary object
If the driving circuit is miniaturized to achieve narrow picture frame, then the mounting area is reduced, but the pitch between connection terminals is narrowed causing reduced connection reliability
Solution Approach 1:
The patent transitions from planar integration on a single substrate to three-dimensional arrangement by placing switching elements and driving circuit on different substrates (insulating and semiconductor respectively). This dimensional change allows compact mounting while maintaining adequate terminal pitch for reliable connections.
3Use of energy by moving object
If a single voltage power source is used at low voltage, then power consumption is reduced, but additional booster circuit is required to generate necessary driving voltages
Solution Approach 1:
The patent designs the insulating substrate to serve multiple functions: as a carrier for switching elements, as a structural support, and as an interface between the booster circuit and driving circuit. This multi-functionality reduces overall device complexity while enabling low-voltage operation with integrated voltage boosting.
Data Source
AI summary
The present invention provides a display device which is used in a miniaturized portable information device, wherein the display device requires a small mounting area for a driving circuit thus realizing free mounting of the driving circuit and also can perform driving thereof with a low-voltage power source such as a battery. In a display device which includes a display panel and a driving circuit on the same substrate, a booster circuit is formed on one side of a display panel together with the driving circuit and is formed by steps substantially equal to steps for pixel transistors. The booster circuit includes a circuit which compensates for the lowering of voltage of a switching element used in the booster circuit attributed to a threshold value of a switching element.