Polygon Mirror Speed Control for Stable Light Intensity
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Solution Overview
Problem
Existing image forming apparatuses require multiple PWM signals to control light intensity and polygon mirror rotation, leading to increased complexity and potential instability during light intensity changes.
Innovation Solution
An image forming apparatus with a light source, light driving unit, polygon mirror, detection unit, speed control unit, and light intensity control unit, where the light intensity control unit converts digital values to analog signals and the speed control unit performs neutral control during light intensity changes, reducing the need for multiple PWM signals and stabilizing polygon mirror rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PWM signals are used to control light intensity for reliable synchronization signal detection, then the reliability of synchronization detection is improved, but the device complexity increases
Solution Approach 1:
The patent changes the control parameter from multiple PWM signals to a single PWM signal combined with analog voltage control. The light intensity is controlled by adjusting the analog voltage level while using one PWM signal for timing control, thereby reducing signal complexity while maintaining detection reliability through precise analog intensity modulation.
Solution Approach 2:
The single PWM signal serves multiple functions: it controls the timing of light emission and works in conjunction with the analog voltage signal for intensity control. This multi-functional approach reduces the total number of signals needed while achieving the same reliability in synchronization detection.
2Manufacturing precision
If light intensity is changed during polygon mirror rotation control, then the image formation quality is improved, but the stability of polygon mirror rotation deteriorates
Solution Approach 1:
The system pre-adjusts the analog voltage signal that controls light intensity before changing PWM duty cycle. By preparing the analog voltage level in advance and coordinating it with PWM changes, the system maintains stable polygon mirror rotation while enabling quality image formation through proper light intensity control.
Solution Approach 2:
The system uses feedback from the synchronization signal detection to monitor polygon mirror rotation status and adjusts light intensity control accordingly. This feedback mechanism ensures that light intensity changes are coordinated with the actual rotation state, maintaining stability while achieving high-quality image formation.
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 allows for stable and efficient light intensity changes while maintaining polygon mirror rotation speed, reducing signal complexity and circuit costs by minimizing the number of PWM signals required.
Implementation Method 1
causing a light beam that a light source emits to reflect in a reflection surface of the polygon mirror
Implementation Method 2
a detection unit configured to detect light that the light source emits and that is reflected by the polygon mirror
Data Source
AI summary
An image forming apparatus includes: a detection unit configured to detect light that a light source emits and that is reflected by a polygon mirror in a predetermined direction, and to output a synchronization signal; a speed control unit configured to perform acceleration/deceleration control of the polygon mirror based on the synchronization signal at a target speed; and a light intensity control unit configured to decide an emission intensity of the light source and notify the digital value to the light driving unit. The speed control unit changes control of the polygon mirror to a neutral control in which neither acceleration nor deceleration control is performed in a case the light intensity control unit changes the light intensity of the light source when the speed control unit is performing the acceleration/deceleration control.