Digital Applanation Tonometer with Optical Projection and Rotary Sensor
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Solution Overview
Problem
Existing applanation tonometers face challenges with precise intraocular pressure measurement due to mechanical readouts, which are difficult to use in low-light conditions and prone to user error, and require time-consuming calibration, especially when retrofitting known mechanical tonometers to digital systems is not feasible.
Innovation Solution
A self-contained handheld applanation tonometer with a light source, measurement head, rotary potentiometer sensor, and microcontroller that converts mechanical pressure into a digital output, allowing for accurate and easy-to-read intraocular pressure measurements, and can be retrofitted onto existing mechanical tonometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical dial readout is used in the applanation tonometer, then the device can be constructed as a self-contained handheld unit, but the measurement precision and ease of reading are deteriorated due to difficulty in low-light conditions and user error
Solution Approach 1:
The patent replaces the mechanical dial readout system with an optical projection system that projects the pressure reading onto a illuminated scale visible in low-light conditions. This substitution eliminates the need for the user to directly read a mechanical dial in dark environments, thereby improving both ease of reading and measurement precision while maintaining the self-contained handheld design.
2Device complexity
If a mechanical dial readout is used in the applanation tonometer, then the device structure can be simplified, but the productivity is deteriorated due to time-consuming readings and calibration
Solution Approach 1:
The optical projection system replaces the mechanical dial, allowing readings to be taken rapidly by simply observing the projected position on the illuminated scale. This eliminates the time required to carefully read and interpret mechanical dial positions, significantly increasing the speed of taking repeat readings while maintaining relatively simple device structure.
3Ease of manufacture
If a mechanical calibration system is used in the applanation tonometer, then the device can be manufactured cost-effectively, but the loss of time is increased due to time-consuming calibration procedures
Solution Approach 1:
The optical projection system uses a light source and projection mechanism that can be calibrated more quickly than mechanical dials. The calibration involves adjusting the projection alignment and illumination, which can be done faster than mechanical zeroing and scaling adjustments, thereby reducing calibration time while maintaining cost-effective manufacturing.
4Ease of operation
If the applanation tonometer is designed as a self-contained handheld device, then the ease of operation is improved, but the measurement precision is worsened due to the necessity of using mechanical readouts
Solution Approach 1:
The patent successfully combines the convenience of a self-contained handheld design with improved measurement precision by replacing the mechanical readout with an optical projection system. The handheld device projects the pressure reading onto an illuminated scale that is visible in low-light conditions, eliminating the precision limitations of mechanical dials while maintaining portability and ease of operation.
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 provides a more accurate, user-friendly, and cost-effective method for measuring intraocular pressure with improved precision and reduced user error, enabling convenient operation in low-light conditions and efficient calibration processes.
Implementation Method 1
the sensor is a rotary potentiometer attached to the cam
Implementation Method 2
a microcontroller configured to convert the electrical output of the sensor into a digital output which corresponds to the pressure applied by the measurement head to the cornea
Implementation Method 3
a measurement head for applying an applanation pressure to a cornea
Data Source
AI summary
The present invention provides an applanation tonometer comprising a light source and a measurement head for applying an applanation pressure to a cornea. Control means for controlling the pressure applied by the measurement head to the cornea are provided and include a cam. The tonometer further comprises a sensor for detecting the rotational position of the cam. The sensor is configured to produce an electrical output and a microcontroller is provided which is configured to convert the electrical output of the sensor into a digital output which corresponds to the pressure applied by the measurement head to the cornea. The sensor is a rotary potentiometer attached to the cam or a digital compass configured to detect the rotational position of the cam.