Light-emitting Element Head Grouping Strategy for Bus Line Reduction
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Solution Overview
Problem
The increasing number of light-emitting element chips in light-emitting element heads for electrophotographic image forming apparatuses leads to a larger drive IC and wider printed circuit boards, resulting in increased costs and complexity due to the need for more lighting signal bus lines and current buffer circuits.
Innovation Solution
A light-emitting element head with a set of light-emitting element chips, where a lighting signal supply unit, a first control signal supply unit, a second control signal supply unit, and a light-emission enable signal supply unit are used to control the light-emitting elements, allowing for grouping of chips to reduce the number of signal bus lines by using common signals for groups of chips and distinct signals for each group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of light-emitting element chips is increased, then the light-emitting element head can cover a wider area or provide higher resolution, but the number of lighting signal bus lines increases, leading to larger drive IC size and wider printed circuit boards
Solution Approach 1:
The patent divides the light-emitting element chips into multiple groups (first group and second group). Each group is controlled by separate control signal lines (first and second control signal lines), allowing independent control of each group. This segmentation reduces the complexity of controlling all chips individually while maintaining the ability to control each chip through coordinated signaling.
Solution Approach 2:
The patent employs periodic control signaling where control signals are supplied in alternating periods to different groups of light-emitting element chips. The first control signal line activates during first periods while the second control signal line activates during second periods, creating a time-division multiplexing effect that reduces the total number of simultaneous signal lines needed.
2Quantity of substance
If the number of light-emitting element chips is increased, then more light can be emitted or coverage is improved, but the printed circuit board width must be increased to accommodate more low-resistance lighting signal bus lines
Solution Approach 1:
The patent segments the control of light-emitting element chips into multiple groups, each controlled by dedicated control signal lines. This allows the use of fewer, lower-current bus lines for power supply since not all chips need to be driven simultaneously at full current, thereby reducing the required printed circuit board width.
Solution Approach 2:
By implementing periodic control where different groups of chips are activated in alternating time periods, the patent reduces the peak current requirements for the bus lines. This time-division approach allows the use of narrower, lower-current bus lines while still achieving the required total light output through coordinated periodic activation of all chip groups.
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 configuration reduces the number of signal bus lines required, thereby minimizing the size and cost of the printed circuit board while maintaining efficient light-emission control across the light-emitting element chips.
Implementation Method 1
each light-emitting element chip includes a light-emitting element array formed of light-emitting elements such as light emitting diodes (LEDs) arrayed in a line
Data Source
AI summary
The light-emitting element head includes: a first signal supply unit supplying a first signal for sequentially specifying a plurality of light-emitting elements one by one as a control target for control in common to light-emitting element chips; a second signal supply unit supplying second signals for giving an instruction to emit or not to emit light to one of the elements specified as the control target to a set of light-emitting element chips so that each of the signals is supplied in common to plural light-emitting element chips belonging to each of N groups into which the set of chips are divided; and an enable signal supply unit that supplies enable signals for allowing the set of chips to receive the second signals which are different from one another so that the enable signals are supplied respectively to the chips belonging to each of the N groups.