Time-of-Flight Sensor for Thin Media Detection
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Solution Overview
Problem
Current printing devices face challenges in accurately detecting the presence of print media in a media bin, especially when the thickness is below the minimum measurable threshold, and they often rely on contact or mechanical sensors that can damage the media and are prone to failure.
Innovation Solution
The use of a time-of-flight sensor with a first emitter and a second emitter to differentiate between signal and noise photons, allowing the detection of print media based on photon count and distance measurement, eliminating the need for contact sensors and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact or mechanical sensors are used to detect print media presence, then detection capability is provided, but media damage occurs and sensor failure rate increases
Solution Approach 1:
The patent replaces mechanical contact sensors with an optical time-of-flight sensor system that uses photons to detect media presence. The system employs a first emitter to send signal photons and a second emitter to send noise photons, with the sensor measuring the time difference for photons to reflect off the media surface. This non-contact optical measurement eliminates mechanical wear and media damage while maintaining reliable detection capability.
2Measurement precision
If time-of-flight sensor is used to detect thin media, then detection accuracy for thin sheets improves, but differentiation between signal and noise photons becomes more challenging
Solution Approach 1:
The patent segments the photon source into two distinct emitters: a first emitter that sends signal photons and a second emitter that sends noise photons. The sensor separately processes photons from each emitter and calculates the time difference between their reflections. This segmentation allows the system to differentiate between signal and noise photons even when detecting thin media, as each photon type has a distinct temporal signature that can be independently measured and compared.
Solution Approach 2:
The system uses periodic emission of signal and noise photons from the two emitters, with the sensor measuring reflections in alternating or sequential periods. By establishing periodic emission patterns and corresponding measurement intervals, the system can distinguish signal photons from noise photons based on their temporal patterns, enabling accurate detection of thin media despite the complexity of photon differentiation.
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
Accurately determines the presence of print media, including thin sheets, without damaging the media and reducing sensor failure, enabling reliable operation and media detection regardless of thickness.
Implementation Method 1
A printing apparatus detects the presence of a print media on a media bin or when the media bin is empty using a time-of-flight sensor
Implementation Method 2
A second emitter may transmit photons toward the sensor. When print media is on the media bin, the print media may diffuse photons from the second emitter reducing the count of photons received at the receiver of the sensor
Implementation Method 3
When print media is on the media bin, the print media may diffuse photons from the second emitter reducing the count of photons received at the receiver of the sensor
Data Source
AI summary
A printing apparatus includes a media bin and a sensor, directed toward the media bin, having a first emitter and a receiver. The printing apparatus further includes a second emitter to emit photons toward the optical sensor, and a controller. The controller determines presence of a print media on the media bin based on a count of photons received from a source other than the first emitter, including the second emitter.