Optical Writing Synchronization With Dual-Color Gain Switching
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses face challenges in accurately detecting the writing start timing of electrostatic latent images due to variations in laser beam power and potential stray light, leading to detection omissions and errors.
Innovation Solution
The apparatus incorporates a synchronization detector that uses multiple light emitters of different colors, a gain switch circuit, and a gain-control-signal selection circuit to stabilize light emission and adjust gain based on light-emission control signals, ensuring consistent detection of writing start timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light sensor is used to detect the scanning position of the laser beam for synchronization, then the writing start timing can be determined, but detection omissions and errors occur when laser beam power varies or stray light is present
Solution Approach 1:
The patent changes the detection parameter by introducing a second light emitter with different color/wavelength light. The synchronization detector is designed to detect both the first light (from the laser beam) and the second light (from the second light emitter), allowing it to distinguish between actual laser beam presence and stray light conditions, thereby improving detection reliability under varying laser power conditions
Solution Approach 2:
The second light emitter acts as an intermediary reference signal. By detecting both the first light (laser beam) and the second light (reference light), the synchronization detector can determine writing start timing more reliably, using the second light as a mediator to calibrate or reference the detection process against stray light and power variations
2Device complexity
If the gain of the synchronization detection circuit is fixed, then the circuit is simple, but detection accuracy deteriorates when the amount of light fluctuates
Solution Approach 1:
The patent introduces dynamic gain adjustment capability to the synchronization detection circuit. The gain of the detection circuit can be switched based on the detected light conditions, allowing the system to adapt to fluctuating laser beam power while maintaining detection accuracy. This dynamic adjustment is achieved through control signals that switch between different gain states in the detection circuit
3Reliability
If multiple light emitters and gain switching circuits are added to improve detection reliability, then detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The second light emitter serves multiple functions: it acts as a reference signal for synchronization detection, provides a marker for timing reference, and enables the system to distinguish between actual laser beam presence and stray light conditions. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity
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 ensures reliable detection of writing start timing, preventing stray light and detection omissions, even with varying laser beam power, thereby maintaining image quality and reducing circuit complexity and cost.
Implementation Method 1
The optical writing device includes a first light emitter to irradiate the photoconductor with a first light of a first color and a second light emitter to irradiate the photoconductor with a second light of a second color
Implementation Method 2
The reflector has multiple reflection faces to rotate to deflect the first light emitted from the first light emitter and the second light emitted from the second light emitter to scan the photoconductor with the first light and the second light in one direction
Implementation Method 3
The synchronization detector detects the first light and the second light to detect the writing start timing of the electrostatic latent image on the photoconductor
Data Source
AI summary
An image forming apparatus includes a photoconductor to form an electrostatic latent image, an optical writing device, a first light emitter, a second light emitter, a reflector, a synchronization detector, and circuitry. The optical writing device includes a first light emitter to irradiate a first light and a second light emitter to irradiate a second light. The reflector deflects the first light and the second light. The synchronization detector detects the first light and the second light to detect a writing start timing of the electrostatic latent image. The circuitry outputs a light-emission control signal to control light emission state, outputs multiple gain signals corresponding to the first light emitter and the second light emitter, selects one gain signal from the multiple gain signals as a gain selection signal, and switches a gain of the synchronization detector based on the one gain signal.