Frequency Counter Circuit for Handwriting Apparatus
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Solution Overview
Problem
Conventional frequency counters in handwriting apparatuses face interference issues due to ambient signals, leading to voltage errors and inaccurate pressure gradation measurements when using phase discriminators or integrators for pressure-integration signals.
Innovation Solution
A frequency counter module that outputs a high-frequency clock signal, comprising a source count module, motion count module, logic module, switching gate module, signal-capturing module, and control module, which enables precise pressure sensing gradation calculation by switching between transmitter and receiver modes based on predetermined clock pulse values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase discriminator or integrator is used to obtain pressure-integration signals, then pressure sensing capability is enabled, but ambient interference causes voltage errors and reduces measurement accuracy
Solution Approach 1:
The patent extracts and counts only the useful clock signal pulses generated by the electromagnetic pen, separating them from ambient interference. By using a frequency counter to count clock pulses within a specific time period, the system isolates the useful signal (pen pressure information) from harmful ambient electromagnetic interference, thereby improving measurement accuracy while eliminating the voltage errors caused by interference.
2Measurement precision
If frequency counter counts clock signals continuously, then measurement precision improves, but energy consumption increases and affects pen operation
Solution Approach 1:
The patent implements periodic action by counting clock signals only during specific time periods when the electromagnetic pen is actively generating signals. The frequency counter operates intermittently rather than continuously, counting pulses within defined measurement windows and remaining idle otherwise. This periodic operation maintains measurement precision during active periods while significantly reducing overall energy consumption and avoiding interference with pen charging and operation cycles.
3Reliability
If ambient interference is present in pressure-integration signals, then signal processing becomes complex, but filtering may reduce measurement precision
Solution Approach 1:
The patent replaces the traditional mechanical/electronic signal processing approach (phase discriminator, integrator, analog filtering) with a digital counting method. Instead of using analog circuits that require complex filtering to separate signal from noise, the system directly counts clock signal pulses in the digital domain. This substitution eliminates the need for analog filtering stages that could compromise measurement precision, achieving both signal integrity and accurate pressure sensing through straightforward pulse counting.
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
The solution effectively reduces interference and enhances the accuracy of pressure sensing gradation measurements by enabling precise counting of high-frequency clock signals, improving the reliability of handwriting apparatuses.
Implementation Method 1
The electromagnetic board includes a frequency counter, analog-to-digital converter, and a control module or a micro-processor. The frequency counter is connected to a phase discriminator or an integrator.
Implementation Method 2
The frequency-counting module completes counting the high-frequency clock signals when its circular number reaches a third predetermined value.
Data Source
AI summary
A circuit of frequency counter is adapted for an electromagnetic board with an electromagnetic pen. The counter exemplarily includes a source count module, a motion count module, a logic module, a switching gate module, a signal-capturing module, a frequency-counting module and a control module. The source count module counts number of clock pulses of a first clock signal. A receiver mode is switched by the switching gate module when the number reaches a first predetermined value. The motion count module counts number of clock pulses of a second clock signal. A transmitter mode is made by the switching gate module when the number reaches a second predetermined value. When a cumulative number of circular number counted by the frequency-counting module reaches a third predetermined value, the frequency-counting module completes counting a first high-frequency clock signals, and the control module obtains an operating frequency for the electromagnetic pen.