PWM Circuit Justification for Partial Pixel Printing
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Solution Overview
Problem
Current printer technologies lack the ability to accurately control the positional accuracy of ink or toner application, resulting in binary application methods that fail to achieve smooth grayscales and sharp edges in printed images, as they cannot apply ink or toner partially within a pixel space.
Innovation Solution
The implementation of pulse-width-modulation (PWM) circuits that generate left- and right-justified width-modulated pulses, allowing for partial pixel application by selecting between pixel data signals and their inverses based on justification needs, thereby enabling precise control over the shape and size of printed dots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If binary ink or toner application method is used, then the printing process is simple, but the image accuracy and grayscale reproduction are poor
Solution Approach 1:
The patent segments the binary pixel application into multiple sub-pixels within each pixel space. By dividing a pixel into several smaller sub-pixels that can be individually controlled, the system achieves grayscale reproduction and partial pixel application while maintaining the overall pixel structure. This segmentation allows for precise control of ink/toner distribution without requiring complete process redesign.
Solution Approach 2:
The patent introduces dynamic control of pixel justification (left, right, center alignment) and sub-pixel activation based on image content requirements. The system dynamically adjusts which sub-pixels are activated and their positional justification within each pixel space, enabling adaptive grayscale reproduction and sharp edge rendering. This dynamic approach transforms the static binary application into a flexible multi-level control system.
2Adaptability or versatility
If screens with offset color planes are used, then color images can be produced, but moire patterns appear in the final image
Solution Approach 1:
The patent applies different justification modes (left, right, center) to different pixels based on their local requirements. By analyzing the image content and applying appropriate justification locally to each pixel or group of pixels, the system optimizes edge rendering and grayscale accuracy in specific regions without affecting the entire image. This local adaptation helps prevent moire patterns by varying the dot distribution locally rather than using a fixed screen pattern throughout.
Solution Approach 2:
The patent performs preliminary processing of pixel data to determine justification requirements before actual ink/toner application. By pre-calculating which pixels require left, right, or center justification and which sub-pixels should be activated, the system prepares the optimal dot distribution pattern in advance. This preliminary action allows the offset color planes to be properly aligned and rendered, preventing moire patterns from appearing in the final composite image.
3Manufacturing precision
If partial pixel printing is implemented, then edge sharpness and halftone accuracy improve, but additional control circuitry is required
Solution Approach 1:
The patent combines multiple control functions (pixel justification selection, sub-pixel activation, PWM modulation) into an integrated control system. By merging the justification selection logic with the existing PWM pixel data processing, the system achieves partial pixel printing and edge sharpness enhancement without requiring completely separate control circuits. The combined approach leverages existing hardware resources while adding minimal additional complexity.
Data Source
AI summary
The methods and systems presented herein use well-known logic devices in combination with one or more pulse-width-modulation (PWM) devices in order to create left- and right-justified width-modulated pulses. In some embodiments, justification ability is added without the need to alter an existing PWM device. In some embodiments, the generation of justified pulses is accomplished by a logic circuit in combination with an inherently left- or right-justified PWM device. Some embodiments of the present invention may include, for example, any combination of logical selectors, inverters, and flip-flops. In some embodiments, a justification circuit may receive as input any combination of one or more bits of pixel data, one or more bits of justification selection data, and one or more clock signal. In some embodiments, a justification circuit may output one more signals representing left or right-justified pulses.