Dot Matrix Printer Counter-Pressure Compensation Mechanism
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Solution Overview
Problem
Dot matrix printers often produce non-uniform print quality due to varying pressing forces along the counter-pressure element, resulting in decreased contrast in marginal areas of the print image.
Innovation Solution
A compensation mechanism using a torsion-proof compensating bar and conversion mechanisms with gear racks and gear wheels ensures a uniform pressing force across the entire print area by transmitting movements between the counter-pressure element's end regions, maintaining the element's parallel orientation to the transport plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one biasing element each is provided at both ends of the counter-pressure element, then the counter-pressure element is effectively supported, but the pressing force becomes non-uniform with maximum in the central area and decrease toward the ends
Solution Approach 1:
The patent introduces a compensating bar that changes the positional parameter of the counter-pressure element to compensate for the non-uniform pressing force distribution. By allowing controlled displacement and rotation, the system adjusts the pressing force distribution to achieve uniformity across the entire counter-pressure element length.
Solution Approach 2:
The compensating bar acts as an intermediary component between the biasing elements and the counter-pressure element. It mediates the force transmission and distributes the pressing force uniformly by converting the non-uniform end forces into a uniform distributed force along the counter-pressure element through its rotational movement.
2Stability of the object's composition
If the counter-pressure element is rigidly fixed, then structural stability is achieved, but the print contrast decreases in marginal areas due to non-uniform pressing force
Solution Approach 1:
The patent transforms the rigid fixed structure into a dynamic system where the counter-pressure element can displace and rotate relative to the print head through the compensating bar mechanism. This dynamic adjustment allows the system to maintain uniform pressing force distribution while preserving overall structural stability during the printing process.
3Adaptability or versatility
If the printing material thickness varies over the print area, then different pressing forces are naturally required, but a fixed counter-pressure element cannot adapt resulting in tilting and non-uniform print quality
Solution Approach 1:
The compensating bar enables the counter-pressure element to dynamically adjust its position and orientation in response to varying printing material thickness. This dynamic adaptation allows the system to maintain uniform pressing force across the entire print area regardless of material thickness variations, preventing tilting and ensuring consistent print quality.
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 achieves uniform print quality over the entire print area by maintaining consistent pressing force and preventing tilting of the counter-pressure element, even with varying printing material thickness, thereby enhancing image contrast.
Implementation Method 1
Each conversion mechanism comprises a gear rack and a gear wheel element, the gear wheel element engaging with the gear rack
Implementation Method 2
each biasing element comprises at least one coil spring
Data Source
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AI summary
A dot matrix printer (10) comprises a printing unit (14) including a print head (16) and an elongated counter-pressure element (20) between which a printing material can be guided along a transport plane, and at least one biasing element (18) on which the counter-pressure element (20) is mounted and biased against the print head (16). Both end regions (38, 40) of the elongated counter-pressure element (20) are each coupled via a conversion mechanism (34, 36) to a stationary, torsion-proof compensating bar (32) that is rotatably mounted about its longitudinal axis. A displacing movement of one of the two end regions (38, 40) of the counter-pressure element (20) directed transversely to the transport plane is converted via the associated conversion mechanism (34, 36) into a rotary motion of the compensating bar (32). This rotary motion of the compensating bar (32) is converted via the respective other conversion mechanism (36, 34) into a compensation movement of the other end region (40, 38) of the counter-pressure element (20), which compensation movement has the same direction as the mentioned displacing movement.