Pixel Row Emission Gating to Prevent Pre-Write Luminance Errors
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Solution Overview
Problem
The display quality is deteriorated when pixel rows changed from non-display to display regions emit light before an image signal is written, causing luminance differences due to image retention.
Innovation Solution
A light emitting device with a pixel array and control circuits that include a holding circuit and gate circuit to manage the supply of write and light emission signals, ensuring that pixels only emit light after a valid image signal is written.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display region is shifted to suppress image retention, then image retention is reduced, but display quality deteriorates due to unintended light emission before image signal writing
Solution Approach 1:
A gate circuit is introduced as an intermediary between the light emission control signal and the pixel's light emitting element. This gate circuit selectively permits or blocks light emission based on the state of the image signal, preventing unintended light emission in rows that have not yet received valid image signals while allowing normal light emission in rows that have received valid image signals.
Solution Approach 2:
The pixel circuit performs preliminary writing of image signals into holding circuits before the light emission phase. This preliminary action ensures that valid image data is stored in advance, and the gate circuit uses this pre-written state to control whether light emission is permitted, thereby preventing display quality deterioration from premature light emission.
2Productivity
If pixels in shifted rows emit light before image signal writing, then display refresh is maintained, but luminance differences occur due to image retention
Solution Approach 1:
The gate circuit acts as a mediator that decouples the light emission control signal from the actual light emitting element when the pixel row has not received a valid image signal. This prevents luminance differences by blocking light emission in rows that would otherwise emit light prematurely, while maintaining normal operation in rows with valid image signals.
Solution Approach 2:
The light emission control is made local to each pixel row based on whether that specific row has received a valid image signal. The gate circuit applies different control states (permit or block light emission) to different rows individually, ensuring that only rows with valid image signals emit light, thereby maintaining luminance uniformity across the display.
Data Source
Figure 1
Figure 2~3A
Figure 3B~3C
AI summary
A light emitting device comprising: a pixel array including a plurality of pixels arranged so as to form a plurality of rows; a write control circuit configured to supply a write control signal to a selected row in order to write an image signal in a pixel arranged in a selected row among the plurality of rows; and a light emission control circuit configured to supply a light emission control signal, which instructs light emission, to a selected row among the plurality of rows, wherein the plurality of rows include a row including a holding circuit and a gate circuit, the holding circuit memorizes that the write control signal is supplied to the row including the holding circuit and the gate circuit, and in a case where the light emission control signal is supplied to the gate circuit and the holding circuit memorizes that the write control signal is supplied, the gate circuit outputs the light emission control signal to a pixel arranged in a row including the holding circuit and the gate circuit.