Driver Circuit for Light Emitting Thyristors
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Solution Overview
Problem
Existing image forming apparatus using arrays of light emitting thyristors suffer from unwanted current flow between gates, leading to variations in drive current and resulting in uneven print densities and inadequate print quality due to simultaneous activation of multiple light emitting thyristors.
Innovation Solution
The implementation of a driver apparatus that alternately drives odd-numbered and even-numbered light emitting thyristors in a time division manner, using buffers to isolate adjacent thyristors and prevent current flow between them, thereby maintaining consistent drive current and light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light emitting thyristors are turned on simultaneously, then productivity is improved by emitting multiple lights at the same time, but manufacturing precision deteriorates due to unwanted current flow between gates causing variations in drive current and light output
Solution Approach 1:
The patent divides the array of light emitting thyristors into multiple independent groups, each with its own dedicated driver circuit. This segmentation prevents unwanted current flow between gates by isolating the gate control paths, thereby maintaining uniform drive current and light output across all thyristors while still enabling simultaneous operation of multiple groups for high productivity
Solution Approach 2:
The patent introduces separate driver circuits as intermediary components between the control signal and each group of light emitting thyristors. These driver circuits act as mediators that independently control each thyristor group, preventing direct current flow between gates while maintaining precise control over drive current and light output uniformity
2Illumination intensity
If light emitting thyristors are driven with high current for high light output, then illumination intensity is improved, but object-generated harmful factors worsen due to current variations causing uneven print densities
Solution Approach 1:
The patent segments the drive current control into multiple independent channels, each dedicated to a specific group of light emitting thyristors. This segmentation ensures that high current can be supplied to each group without causing current variations or unwanted current flow between gates, thereby maintaining both high illumination intensity and uniform print density
Solution Approach 2:
The patent introduces driver circuits as intermediary components between the power supply and light emitting thyristors. These drivers act as mediators that regulate and stabilize the drive current to each thyristor group, enabling high current operation for intense light output while preventing current variations that would cause uneven print densities
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 minimizes variations in light output, enhances print quality by ensuring consistent drive current, and improves the operational efficiency of the optical print head, capable of producing high-quality images in both monochrome and full-color applications.
Implementation Method 1
using buffers to isolate adjacent thyristors and prevent current flow between them
Implementation Method 2
causing the light emitting thyristors to emit or not to emit light
Data Source
Figure 1
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AI summary
A driver apparatus drives a plurality of light emitting thyristors (210). Each thyristor includes a cathode (K) connected to the ground, an anode (A), and a gate (G). A driver circuit (162) outputs a drive signal that electrically drives the gate. A level shifter circuit (163) includes an input terminal (T1) connected to the driver circuit (162) and an output terminal (T2) connected to the gate of the thyristor. The level shifter circuit operates such that the drive signal is shifted down in signal level and is outputted to the output terminal (T2) and a signal at the gate inputted to the output terminal (T2) is shifted down in signal level and is outputted to the input terminal (T1). In response to the drive signal outputted from the driver circuit, a current supplying circuit (160) supplies drive current to the anode of the thyristor such that the drive current flows from the anode to the cathode.