Low-Voltage Microcontroller Drives Bistable Display via Charge Pump
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Solution Overview
Problem
Chip cards with dynamic cryptograms require bistable electrophoretic displays that face challenges due to the need for specific microcontrollers capable of providing the necessary voltage, which are expensive and not widely available, and existing solutions like using lithium batteries or external display controllers increase costs and complexity.
Innovation Solution
A process using a standard microcontroller with a programmable memory and a voltage generator to provide the required voltages for an electrophoretic segment display, allowing the display to be driven with a low voltage supply, such as 3V, and generating the necessary +5V and -2V voltages using discreet components like capacitors and transistors, enabling the use of a common low-voltage microcontroller to pilot the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a specific microcontroller integrating a driver for electrophoretic segment display is used, then the display can be controlled with the required voltage, but the cost increases and supply sources are limited
Solution Approach 1:
The patent divides the display control system into two independent parts: a standard low-voltage microcontroller for logic control and a separate voltage generator circuit for providing high voltages. This segmentation allows each component to be optimized independently, using widely available standard microcontrollers rather than requiring expensive specialized integrated solutions.
Solution Approach 2:
The patent introduces a voltage generator circuit as an intermediary component between the low-voltage microcontroller and the high-voltage display. This mediator converts the microcontroller's 0-3V output signals into the required +5V and -2V display voltages, enabling standard microcontrollers to control electrophoretic displays without requiring expensive voltage-capable alternatives.
2Power
If lithium batteries are used to raise voltage to 6V, then the display operating voltage is sufficient, but the cost and space occupied by the battery increase
Solution Approach 1:
The patent replaces the mechanical/chemical battery-based voltage boosting approach with an electronic voltage generator circuit. Instead of using multiple batteries in series or high-voltage batteries, the system uses a charge pump circuit with capacitors and transistors to electronically generate the required +5V and -2V voltages from the microcontroller's low-voltage signals.
3Power
If a DC-DC converter with capacitance-based charge pump is used to increase battery voltage, then the voltage requirement is met, but the efficiency decreases and current increases leading to poor power consumption performance
Solution Approach 1:
The voltage generator uses periodic switching of transistors Q1 and Q2 to charge and discharge capacitors C1-C4 in alternating phases. This periodic action allows the circuit to build up high voltages through capacitive energy storage and transfer, achieving voltage multiplication without the continuous high current draw that would result in poor power consumption performance.
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 allows for the cost-effective production of bistable electrophoretic displays by utilizing standard components and reducing the dependency on specific microcontrollers, making the technology more accessible and flexible for various applications.
Implementation Method 1
a DC-DC converter solution, if possible without inductance, should be used. Such a solution would use a capacitance-based charge pump
Implementation Method 2
a layer (or a film) of microcapsules containing colored particles suspended in a fluid or a gas
Data Source
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AI summary
Method for producing an electrophoretic display device comprising a low-voltage microcontroller. The invention relates to a method for producing a segmented electrophoretic display device (1A) comprising a bistable display (2) operating at predetermined opposing voltages (+dV; -dV) and an electronic circuit (10A, 25) with microcontroller (10, 24) for controlling the display according to a control programme (P). The method is characterised in that it comprises the following steps: - supplying the controller (24), which is different from a specific display controller for a bistable display and configured to deliver voltages (Vsegment), lower in absolute value to the predetermined voltages (+dV; -dV), - compensating said voltages (Vsegment) with at least one compensation voltage (Vcom) to at least reach the predetermined opposing voltages (+dV; -dV). The invention also relates to the corresponding device.