Diversion Thyristor Circuit for Exposure Control in Print Heads
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Solution Overview
Problem
Current light emitting devices in image forming apparatuses, such as printers, face challenges in accurately controlling the exposure amount due to variations in light emitting thyristor characteristics and manufacturing variations, leading to complexity and cost in electronic circuits for precise light-on period control.
Innovation Solution
The implementation of a light emitting part comprising plural light emitting thyristors, a light-on signal line, and a diversion thyristor, where the potential of the light-on signal line is set to allow the diversion thyristor and at least one light emitting thyristor to be in the on state in parallel, enabling control of the exposure amount by switching between high and low exposure modes through current diversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic circuits are designed to precisely control the light-on period of light emitting thyristors to compensate for manufacturing variations, then exposure amount control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
A diversion thyristor is introduced as an intermediary component between the light-on signal line and the light emitting thyristors. This diversion thyristor acts as a mediator that can redirect current flow to compensate for manufacturing variations in the light emitting thyristors, thereby maintaining exposure accuracy without requiring complex electronic control circuits. The diversion thyristor effectively mediates the current distribution to achieve precise exposure control through a simple binary switching mechanism rather than complex analog control.
Solution Approach 2:
The invention changes the control parameter from continuous light-on period modulation to discrete current path selection. By using the diversion thyristor to switch between different current paths (through the diversion thyristor or through the light emitting thyristor), the system achieves exposure amount control through parameter changes in the circuit topology rather than through complex timing control, simplifying the electronic circuit requirements.
2Manufacturing precision
If the light-on period is extended to compensate for low luminance in certain wavelength ranges, then exposure amount is improved, but productivity decreases due to increased scanning time
Solution Approach 1:
The diversion thyristor is selectively activated only for specific light emitting thyristors that operate in wavelength ranges with lower luminance (such as violet and blue regions). This local application of current diversion allows extended effective exposure for specific elements without requiring all elements to operate at reduced scanning speeds, thereby maintaining overall productivity while achieving uniform exposure across different wavelength ranges.
Solution Approach 2:
The current diversion through the diversion thyristor provides an excessive or augmented current path specifically for light emitting thyristors with lower luminance output. This partial action approach applies enhanced current only where needed (for specific wavelength ranges) rather than uniformly across all light emitting elements, allowing compensation for low luminance without requiring a global reduction in scanning speed.
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 simplifies the control of exposure amount by switching between high and low exposure modes, reducing the complexity and cost of electronic circuits while maintaining accuracy, by utilizing the diversion thyristor to adjust current flow to light emitting thyristors.
Implementation Method 1
plural light emitting thyristors that each have an anode and a cathode and that emit light in the on state
Implementation Method 2
a diversion thyristor that has an anode and a cathode, the anode or the cathode which is connected with the light-on signal line, and that diverts current, the current which flows to a light emitting thyristor
Data Source
AI summary
A light emitting part includes plural light emitting thyristors that each have an anode and a cathode and that are lit in the on state; a light-on signal line that is connected with the cathodes or the anodes of the plural light emitting thyristors and that supplies current, the current which causes the plural light emitting thyristors to be lit; and a diversion thyristor that has an anode and a cathode, the anode or the cathode which is connected with the light-on signal line, and that diverts current, the current which flows to a light emitting thyristor to be lit among the plural light emitting thyristors in the on state. A potential of the light-on signal line may be set so that the diversion thyristor and at least one light emitting thyristor among the plural light emitting thyristors become the on state in parallel.