Multiphase Clock PWM Generator for High-Resolution Image Forming
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Solution Overview
Problem
Existing PWM signal generation methods face challenges in increasing image resolution due to limitations in the operating speed of flip-flop circuits, making it difficult to further enhance the resolution of PWM signals in electrophotographic image forming apparatuses.
Innovation Solution
A PWM signal generating apparatus utilizing a multiphase clock generating portion to produce clocks with different phases, a PWM pattern converting portion to convert input pulse data into pattern data, and an encoder-decoder circuit to generate high-resolution PWM signals by synchronizing clock phases and bit patterns, allowing for precise control of pulse widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the operating speed of flip-flop circuit is increased to generate higher resolution PWM signal, then the PWM signal resolution is improved, but the circuit reaches its upper speed limit and becomes difficult to further increase resolution
Solution Approach 1:
The patent divides the high-resolution PWM signal generation into multiple stages using parallel serial conversion circuits. Each circuit processes a portion of the data bits, and their outputs are combined to achieve the final high-resolution PWM signal. This segmentation allows the system to achieve higher effective resolution without requiring any single flip-flop circuit to operate beyond its speed limits.
Solution Approach 2:
The patent transitions from a single-dimensional approach (one high-speed flip-flop circuit) to a multi-dimensional approach by using multiple parallel conversion circuits operating simultaneously. Each circuit handles a subset of bits, and the combined output achieves the target resolution. This dimensional expansion in the circuit architecture enables higher resolution without increasing the operating speed of individual components.
2Measurement precision
If parallel serial conversion circuit is used to generate PWM signal with higher resolution, then image resolution is improved, but the device complexity increases
Solution Approach 1:
The patent employs multiple parallel serial conversion circuits that can be configured to handle different bit assignments. These circuits serve multiple functions: they can process different segments of the PWM data, support various resolution requirements, and be adapted for different image forming applications. This multi-functionality reduces the need for completely different circuit designs for different resolution requirements.
Solution Approach 2:
The system dynamically assigns different bit patterns to different gray levels through the parallel conversion circuits. The circuit can adapt its operation based on the required resolution and image data characteristics, optimizing performance while managing complexity. The dynamic configuration allows the same hardware structure to serve multiple resolution requirements.
Data Source
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AI summary
A PWM signal generating apparatus configured to generate a PWM signal by applying parallel serial conversion to pattern data obtained by converting input data into a waveform pattern of a PWM signal having one pulse divided into a predetermined number of pulses, the PWM signal generating apparatus including: a clock generating circuit configured to generate a plurality of clock signals having mutually different phases; a conversion circuit configured to convert the input data into the waveform pattern of the PWM signal; an encoding circuit configured to generate, from the waveform pattern, a plurality of encoded signals synchronized with respective clocks of the plurality of clock signals generated by the clock generating circuit; and a decoding circuit configured to generate the PWM signal from the plurality of encoded signals output from the encoding circuit.