Optical Joystick Detection Circuit for Mobile Cursor Control
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Solution Overview
Problem
Existing mobile device joysticks face challenges in providing reliable, sensitive, and compact control with low power consumption and cost, especially as display sizes and menu complexity increase, requiring improved detection systems for precise cursor control.
Innovation Solution
A detection system comprising a light source, a reflecting unit, detectors, an analogue-to-digital converter, and a common mode controller, which converts light intensity changes into digital signals for precise detection of joystick movements, including the click function, using a simplified circuit arrangement that can be integrated on a single chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a joystick with five switches under a dome knob is used for cursor control, then the control functionality is achieved, but the device complexity and power consumption increase
Solution Approach 1:
The patent replaces the mechanical switch-based joystick system with an optical detection system. A light source emits light that reflects off a light reflecting unit on the movable object (joystick), and detectors detect the reflected light to determine movement. This substitution eliminates the need for multiple mechanical switches and dome structure, reducing device complexity while maintaining cursor control functionality.
Solution Approach 2:
The optical detection system serves multiple functions: it detects movement in the base plane (X and Y directions) for cursor control and simultaneously detects pressing operations (Z direction) for click functions. This multi-functionality is achieved through a unified optical detection architecture with detectors arranged to sense light intensity changes from different movement directions, eliminating the need for separate mechanical switch systems.
2Adaptability or versatility
If the display size and menu complexity increase, then the functionality of mobile devices is improved, but the requirement for precise and reliable cursor control increases the detection system complexity
Solution Approach 1:
The patent employs an optical detection system that uses light reflection and detection to determine movement of the movable object. This replaces complex mechanical switch arrays with a simpler optical system consisting of a light source, light reflecting unit, and detectors. The system achieves high precision detection suitable for large displays and complex menus through analogue-to-digital conversion of detector signals.
Solution Approach 2:
The system uses analogue-to-digital converters to convert detector signals into digital values, enabling precise measurement of light intensity changes. Common mode controllers regulate current sources to maintain stable detection despite variations in light intensity. These parameter changes and conversions enable high precision detection required for complex displays while keeping the physical detection system simple.
3Volume of moving object
If a compact and robust joystick is used, then the mobile device size is reduced, but the detection precision and reliability may be compromised
Solution Approach 1:
The patent replaces bulky mechanical switch mechanisms with a compact optical detection system. The light source, light reflecting unit, and detectors can be arranged in a compact configuration on a substrate, enabling miniaturization of the joystick while maintaining detection precision through optical signal measurement rather than mechanical switch actuation.
Solution Approach 2:
The system maintains detection precision in a compact form by using analogue-to-digital converters with common mode control. The converters precisely measure light intensity changes detected by the detectors, and common mode controllers stabilize the measurement against intensity variations. This enables high precision movement detection in a compact joystick design suitable for modern mobile devices.
4Ease of operation
If traditional joystick switches are used, then the click function is achieved, but the power consumption increases
Solution Approach 1:
The patent replaces power-consuming mechanical switch systems with an optical detection system. The light source can be implemented as an LED which is energy-efficient, and the detectors convert light signals to electrical signals without requiring continuous high power. The analogue-to-digital conversion and common mode control enable reliable click detection with lower overall power consumption compared to maintaining multiple mechanical switches in standby.
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
Enables reliable and precise detection of joystick movements and click functions with reduced circuit complexity, ensuring efficient and cost-effective integration in mobile devices, while maintaining low power consumption.
Implementation Method 1
a reflecting unit being arranged in functional connection with the movable object and being adapted for reflecting the emitted light
Implementation Method 2
at least one detector for detecting the reflected light and outputting detection signals
Implementation Method 3
an analogue-to-digital converter which includes at least one current source for obtaining a digital signal
Data Source
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AI summary
The present invention relates to a detection system for detecting movement of a movable object. The detection system comprises a light source (S) for emitting light, a reflecting unit (8) being arranged in functional connection with the movable object (6) and being adapted for reflecting the emitted light, at least one detector (D1 to D4) for detecting the reflected light and outputting detection signals for determining the movement of the movable object, an analogue-to-digital converter which includes at least one current source for obtaining a digital signal, and a common mode controller for outputting at least one common mode signal for controlling the at least one current source, wherein the digital signal which is indicative of the movement of the movable object in a predetermined direction being based on the output signal of the at least one detector and the at least one common mode signal. The present invention also concerns a method of detecting movements of a movable object, as well as an integrated circuit having implemented therein the detection system.