Image Display Device Line Memory Collective Write Method
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Solution Overview
Problem
In image display devices using self-luminous elements like EL and organic EL, inconsistencies in drive transistors lead to inconsistent brightness, reducing image quality due to inefficiencies in current control and light emission timing.
Innovation Solution
Implementing a configuration that uses line memory and a high-speed readout circuit to collectively write signal voltages for multiple lines, allowing variable write-in times based on line conditions, thereby reducing wasteful time and securing longer light emission periods without requiring frame memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a frame memory is provided to secure a long time period for light emission within one frame period, then the light emission period is extended, but the scale of the peripheral circuit becomes great
Solution Approach 1:
The patent divides the display into multiple scan lines and processes them in groups rather than individually. By segmenting the write-in operation across multiple lines simultaneously, the system reduces the time required for each line's write-in operation, thereby extending the light emission period without requiring a frame memory for the entire frame.
Solution Approach 2:
The patent transitions from processing one line at a time (one-dimensional approach) to processing multiple lines simultaneously by adding a line memory that stores data for multiple lines. This dimensional change from single-line to multi-line processing enables longer light emission periods without proportionally increasing peripheral circuit scale.
2Duration of action of moving object
If a line buffer is provided to secure a long time period for light emission within each horizontal period, then the light emission period is extended, but the entire period for a horizontal retrace line cannot practically be a period for light emission
Solution Approach 1:
The patent enables continuous write-in operations across multiple lines by preparing data for subsequent lines during the light emission period of current lines. This continuity eliminates idle time between lines and ensures that the light emission period is maximized without sacrificing write-in efficiency.
Solution Approach 2:
The line memory stores write-in data for multiple lines in advance, allowing the system to prepare subsequent line data while current lines are emitting light. This preliminary action ensures that write-in operations can begin immediately when the light emission period ends, maximizing the utilization of the horizontal period.
3Speed
If signal voltage and triangular wave voltage are rewritten for each period for a horizontal retrace line, then the write-in operation is completed quickly, but the amount of wasteful time during which light cannot be emitted increases
Solution Approach 1:
The patent merges the write-in operations for multiple lines into a single coordinated process. By writing data for multiple lines simultaneously into the line memory and then transferring them to the display in sequence, the system eliminates the repetitive overhead of individual write-in operations, thereby reducing wasteful time while maintaining high write-in speed.
Data Source
AI summary
An image display with high brightness where a long time can be secured for light emission of self-luminous elements can be implemented using only line memories.The period for the writing in of a display voltage (period for writing in of data) continues for a number of lines (three lines), and the reset pulse becomes of a “high” state. Subsequently, operation for three lines is carried out collectively during a triangular wave period (period for writing in of a triangular wave voltage), and only the light emission controlling pulse becomes of a “high” state. During the period for the writing in of a triangular wave voltage, the writing in of a triangular wave voltage from the second time onward is rewriting of a triangular wave voltage, and thus, the period for rewriting the display voltage (dotted line portion) becomes unnecessary, and a longer period for light emission, where the light emission controlling pulse becomes of a “high” state, can be secured.