Pyroelectric Sensor Direction Detection for Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses face challenges in quickly determining user intention and reducing user wait time due to difficulties in accurately detecting human movement and direction with existing pyroelectric sensors, leading to prolonged wait times before returning to normal operation mode.
Innovation Solution
The implementation of a human body detecting device with a pyroelectric sensor and a lens system that forms variable detecting areas, including a non-detecting area, to produce output signals with peak values and frequencies, allowing for accurate judgment of user movement direction and intention, and switching between power supply modes to optimize operation based on detected user actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a pyroelectric sensor is used to detect human body movement, then power consumption is reduced and cost is lowered, but the sensor cannot accurately detect the direction of user movement
Solution Approach 1:
The detection area is divided into multiple segmented regions (first detection area, second detection area, third detection area) arranged in different directions. Each segment corresponds to a specific directional zone, allowing the system to determine movement direction by identifying which segment triggers the detection signal, thereby enabling directional detection while maintaining the low power consumption characteristics of pyroelectric sensors
Solution Approach 2:
A lens is introduced as an intermediary component between the pyroelectric sensor and the external environment. The lens focuses infrared radiation from different directions onto the sensor, enhancing the sensor's ability to detect directional movement while maintaining low power consumption operation
2Loss of energy
If the image forming apparatus waits for button press or hand detection before returning from power saving mode, then power consumption is minimized, but user wait time increases
Solution Approach 1:
The system performs preliminary detection of user approach using the pyroelectric sensor before the user actually interacts with the device. When movement is detected in the predetermined direction, the system proactively transitions from power saving mode to normal operation mode in advance, eliminating user wait time while still maintaining energy efficiency by only activating when needed
Solution Approach 2:
The system continuously monitors the detection output signal and uses this feedback to dynamically adjust power supply mode. The feedback loop enables real-time decision-making about when to transition between power saving and normal operation modes, optimizing both energy consumption and user experience
3Measurement precision
If the pyroelectric sensor detects temperature change when user approaches, then user presence can be detected, but the sensor cannot distinguish whether the user intends to operate the apparatus
Solution Approach 1:
The detection area is segmented into multiple directional zones, and the system analyzes which specific segment triggers detection. By determining the direction of approach based on segment identification, the system can infer user intention (e.g., approaching from the front suggests operational intent, while approaching from the side may indicate passing by), thereby recovering user intention information that would otherwise be lost
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 enables the image forming apparatus to rapidly switch to normal operation mode when a user approaches, reducing wait times and optimizing power consumption by accurately detecting user intention and movement, thereby enhancing user convenience and energy efficiency.
Implementation Method 1
a pyroelectric sensor (also referred to as piezoelectric infrared sensor) that is capable of detecting a human body with less power consumption at low costs. Such a pyroelectric sensor detects a temperature change when a person moves in a detection range of the pyroelectric sensor itself
Implementation Method 2
Japanese Unexamined Patent Publication No. H06-043025 discloses a human body detecting device having a single pyroelectric sensor and a concentrator
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An image forming apparatus(1) comprises: a piezoelectric sensor(202) that produces an variable output signal depending on the amount of infrared energy; a human body detecting device(200) having a lens(203) that forms a detecting area(205a) serving for detecting if the person enters; a peak detection means(104a) that detects a peak of an output signal produced when the person enters the detecting area(205a); an offset voltage judgment means(104a) that judges if the output signal falls to the offset voltage after the peak; a moving direction judgment means(104a) that judges the direction in which the person moves in the detecting area(205a); and a mode control means(104) that switches the power supply mode to a first mode if the power supply mode is found to be a second mode requiring less power than the first mode while the moving direction judgment means(104a) judges that the person moves toward the image forming apparatus(1).