LED Emission Control Circuit for Black Image Light Suppression
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Solution Overview
Problem
Display devices using light emitting diodes (LEDs) suffer from the issue of abnormal light emission during non-emission periods, leading to degraded display quality, particularly in black image rendering due to kick-back phenomena caused by parasitic capacitors in emission control transistors.
Innovation Solution
The display device incorporates an emission control circuit with a diode or transistor in a diode connection state to manage the connection of the LED's second electrode to either a high or low potential power line during emission and non-emission periods, preventing abnormal light emission by controlling the voltage applied to the LED during these periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an emission control transistor is used to control the light emitting diode, then the LED can be controlled during emission period, but parasitic capacitors cause kick-back phenomena leading to abnormal light emission during non-emission period
Solution Approach 1:
A diode is introduced as an intermediary component between the emission control transistor and the light emitting diode. The diode's anode is connected to the drain electrode of the emission control transistor, and its cathode is connected to the second electrode of the light emitting diode. This diode acts as a one-way valve for current flow, preventing kick-back current from flowing back through the LED during the non-emission period, thereby eliminating abnormal light emission while preserving the emission control function.
2Illumination intensity
If high potential power voltage is applied to the second electrode of the light emitting diode during non-emission period, then the LED should not emit light, but abnormal light emission occurs due to kick-back phenomena
Solution Approach 1:
The patent converts the harmful kick-back phenomenon into a beneficial effect by utilizing the diode's directional current blocking property. The kick-back voltage that would normally cause abnormal light emission is now used to forward-bias the diode, which blocks the reverse current path through the LED. This transforms the harmful electrical transient into a useful protective action that ensures complete light suppression during the non-emission period, improving black image quality.
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
This solution effectively suppresses abnormal light emission during non-emission periods, improving the quality of black images and overall display performance by ensuring the LED emits light only during intended emission periods.
Implementation Method 1
an emission control element which is formed by any one of a diode or a transistor in a diode connection state
Implementation Method 2
a light emitting diode which is disposed in each of the plurality of sub pixels and is configured to be controlled in response to an emission period and a non-emission period
Data Source
AI summary
The present disclosure describes various embodiments of a display device. In one embodiment, a display device includes a display panel, a light emitting diode which is disposed in the display panel. The light emitting diode is configured to be controlled in response to an emission period and a non-emission period. The display device includes a driving transistor coupled to the light emitting diode. The display device includes an emission control circuit which is coupled between the light emitting diode and a high potential power line and between the light emitting diode and a low potential power line, in which the emission control circuit is configured to couple the light emitting diode to any one of the high potential power line and the low potential power line in response to each of the emission period and the non-emission period.