Exposure Head Variable-Gap Structure for Stable Optical Output
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Solution Overview
Problem
Conventional LED exposure heads in electrophotographic image forming apparatuses face fluctuations in optical output due to temperature rises from the driver IC, which are not adequately addressed by existing heat dissipation methods.
Innovation Solution
The exposure head design includes a substrate and lens array separated from a holder by an adhesive, with varying gap sizes to stabilize the relative positions and reduce optical output fluctuations through controlled thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat dissipation member is in contact with the driver IC and holder to dissipate heat, then the temperature rise of the driver IC is reduced, but the relative positions of the LED and lens array and the image bearing member still change due to thermal expansion, causing fluctuations in optical output
Solution Approach 1:
The substrate is divided into two distinct facing portions: a first facing portion with a smaller gap to the holder and a second facing portion with a larger gap. This segmentation allows different regions of the substrate to experience different thermal expansion effects, with the adhesive primarily acting through the second facing portion to maintain stable positioning despite temperature changes.
Solution Approach 2:
The gap sizes between the substrate and holder are intentionally made asymmetric, with the first gap being smaller than the second gap. This asymmetric design creates a controlled thermal expansion path where the adhesive fixes the substrate at specific points, allowing the substrate to expand uniformly away from the holder without causing relative position shifts between the LED and lens array.
2Stability of the object's composition
If the substrate and holder are fixed closely together, then structural stability is improved, but thermal expansion causes relative position changes that fluctuate optical output
Solution Approach 1:
Different regions of the substrate have different gap characteristics: the first facing portion has a smaller gap providing localized structural support, while the second facing portion has a larger gap that accommodates thermal expansion. The adhesive is applied specifically at the second facing portion where the larger gap exists, creating a localized fixation point that allows overall thermal expansion without compromising structural stability.
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 effectively minimizes optical output fluctuations by reducing thermal expansion-induced movements, maintaining consistent light quantity despite temperature changes.
Implementation Method 1
The substrate includes a first facing portion facing the holder with a first gap therebetween in a lateral direction of the substrate, and a second facing portion facing the holder with a second gap therebetween which larger than the first gap in the lateral direction, and the adhesive fixes the substrate and the holder via the second facing portion
Data Source
AI summary
There is provided an exposure head including: a holder; a substrate on which a plurality of light-emitting elements is mounted along a rotational axis direction of the image bearing member, a lens array including a plurality of lenses configured to transmit light emitted from the plurality of light-emitting elements and condense the light on the image bearing member; and an adhesive fixing the substrate and the lens array to the holder in a state in which the plurality of light-emitting elements and the lenses face each other and in a state in which the substrate and the holder are separated from each other. The substrate includes a first facing portion facing the holder with a first gap therebetween in a lateral direction of the substrate, and a second facing portion facing the holder with a second gap therebetween which is larger than the first gap in the lateral direction, and the adhesive fixes the substrate and the holder via the second facing portion.