Cylindrical Prism Optical Sensor for Reflective Ink Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical sensors used in printers to detect ink levels are ineffective when the ink is reflective, as the reflective ink directs ambient light into the photodetector, leading to incorrect electrical signals and failure to detect the ink level accurately.
Innovation Solution
A reflective ink level optical sensor with a cylindrical prism is used instead of a conical prism, allowing the photodetector to generate signals indicative of whether a reflective fluid is contacting the prism, enabling accurate detection of both reflective and non-reflective ink levels in the reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conical prism is used in the optical sensor, then the sensor can effectively detect non-reflective ink levels through total internal reflection, but the sensor becomes inoperative when detecting reflective ink levels because reflected ambient light enters the photodetector
Solution Approach 1:
The patent changes the prism geometry from a symmetric conical shape to an asymmetric cylindrical shape with a flat exterior surface. This asymmetric design blocks the path of reflected ambient light from reaching the photodetector while preserving the total internal reflection mechanism for detecting ink levels, thereby resolving the contradiction between reliability with non-reflective ink and adaptability to reflective ink.
2Measurement precision
If the prism exterior surface is angled (conical), then total internal reflection occurs effectively for non-reflective liquids, but reflective liquids cause harmful light reflection into the photodetector
Solution Approach 1:
Instead of using an angled conical surface that directs reflected light toward the photodetector, the patent inverts the approach by using a flat cylindrical surface that blocks reflected light paths. This inversion of the light-blocking strategy eliminates the harmful reflection effect while maintaining measurement precision through the preserved total internal reflection mechanism.
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
The cylindrical prism design allows for effective detection of reflective ink levels, enabling the controller to accurately monitor and manage ink supplies in printers, ensuring timely replenishment and preventing overfilling.
Implementation Method 1
the conical prism totally internally reflects (TIR) the light on a path that is parallel to the emitted light beam so it strikes the photodetector
Implementation Method 2
the photodetector generates an electrical signal that is inversely proportional to the intensity of the light striking the photodetector
Implementation Method 3
the exterior surface of the cylindrical prism is parallel to the second end of the housing and the exterior surface having a width corresponding to a width of the second end of the housing to enable the photodetector to generate a signal indicative of whether a reflective fluid is contacting the prism
Data Source
AI summary
An optical sensor enables a level of reflective fluid to be detected. The optical sensor includes a prism mounted at one end of a housing. The prism has an exterior surface that is parallel to the end of the housing and a width that corresponds to a width of the end of the housing. A photoemitter and a photodetector are mounted at another end of the housing to enable light emitted by the photoemitter to be reflected by the prism when the prism contacts reflective fluid and to enable light emitted by the photoemitter to pass out of the sensor when the prism is in contact with air.