Document Detection Using Dynamic Light Modulation
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Solution Overview
Problem
Existing document detecting apparatuses in multi-function peripherals face challenges in accurately distinguishing between projected light and stray light, leading to erroneous detection of document presence or absence.
Innovation Solution
A document detecting apparatus comprising a light-emitting element, a photoelectric conversion element, and a detection processor that adjusts the light quantity and detects the presence or absence of a document based on changes in the output value from the photoelectric conversion element, effectively differentiating between projected light and stray light through stepwise or continuous changes in light quantity and corresponding amplifier gains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflection-type or transmission-type sensor projects light to detect document presence, then document detection can be performed, but stray light causes erroneous detection
Solution Approach 1:
The patent applies dynamics by continuously changing the light quantity emitted by the light-emitting element and corresponding amplifier gain in a stepwise or continuous manner. This dynamic adjustment creates a time-varying detection scheme where the system transitions between different light quantity states, enabling differentiation between projected light (which changes with the light-emitting element) and stray light (which remains relatively constant).
Solution Approach 2:
The patent implements parameter changes by varying the light quantity parameter of the projected light and the amplifier gain parameter in coordination. By changing these parameters over time and observing the corresponding changes in the output value from the photoelectric conversion element, the system can identify patterns that distinguish projected light from stray light, thereby improving detection accuracy.
2Reliability
If the sensor receives stray light along with projected light, then detection coverage is maintained, but detection accuracy deteriorates due to erroneous detection
Solution Approach 1:
The patent employs feedback by continuously monitoring the output value from the photoelectric conversion element while systematically varying the light quantity and amplifier gain. The detection processor analyzes the relationship between the controlled parameter changes and the resulting output changes, using this feedback information to distinguish between projected light and stray light components, thereby maintaining reliable and accurate detection.
Solution Approach 2:
The system uses dynamic parameter adjustment of light quantity and gain, creating a time-varying detection process. This dynamic approach allows the system to observe how the output value responds to controlled changes, enabling reliable discrimination between projected light (which shows correlated changes) and stray light (which shows inconsistent or constant patterns).
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 approach enhances the accuracy of document detection by reliably distinguishing between projected light and stray light, ensuring high precision in detecting document presence and size, regardless of document density or environmental light interference.
Implementation Method 1
a photoelectric conversion element to output an electric signal obtained by converting the light from the detection position of the document
Data Source
AI summary
According to one embodiment, a document detecting apparatus includes a light-emitting element, a photoelectric conversion element, a light-emission controller and a detection processor. The light-emitting element projects light onto a detection position of a document. The light-emitting element is not used for reading an image of the document. The photoelectric conversion element converts light projected onto the detection position into an electric signal and outputs the electric signal. The light-emission controller changes the light quantity of the light emitted by the light-emitting element during a predetermined interval. The detection processor detects the presence or absence of the document at the detection position of the document based on whether a value of the output electric signal during the predetermined interval changes in correspondence to the change of the light quantity caused by the light-emission controller.