Infrared Receiver Comparing Circuit for Short Pause Pulse Accuracy
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Solution Overview
Problem
Infrared receivers face challenges in maintaining error prevention capabilities while ensuring output pulse stability, particularly when receiving transmission codes with short pulse widths and pause periods, as existing hysteresis comparator circuits struggle to adjust discharging periods effectively without degrading error prevention capabilities.
Innovation Solution
The comparing circuit incorporates a charging and discharging circuit with current-value adjusting means, utilizing multiple comparator circuits to compare capacitor voltages with varying threshold voltages, allowing for precise adjustment of charging and discharging periods to maintain pulse period consistency and error prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hysteresis comparator circuit is used to prevent errors, then error prevention capability is improved, but the output pulse period cannot match the input pulse period when pause periods are short
Solution Approach 1:
The patent applies dynamics by making the discharging current adjustable based on the input signal state. When the input signal is at a high level, the discharging current is set to a first value; when at a low level, it switches to a second value. This dynamic adjustment allows the circuit to adapt the discharging period to match the input pulse period, resolving the contradiction between error prevention and pulse period accuracy.
Solution Approach 2:
The patent changes the parameter of discharging current based on the input signal level. By switching between two current values (first value when input is high, second value when input is low), the circuit modifies its operational parameters to achieve both error prevention through hysteresis and accurate pulse period reproduction, even for short pause periods.
2Speed
If the discharging period is shortened to respond to short pulse widths, then responsiveness is improved, but error prevention capability is degraded
Solution Approach 1:
The patent uses dynamic adjustment of the discharging current based on input signal state. When the input is at a low level (indicating a short pause period), the discharging current is increased to a second value that is larger than the first value, thereby shortening the discharging period and improving responsiveness without compromising error prevention when the input is high.
Solution Approach 2:
The patent changes the discharging current parameter according to the input signal level. By setting the discharging current to a larger second value when the input is low, the circuit achieves faster response to short pulse widths while maintaining error prevention capability through the hysteresis mechanism when the input is high.
3Device complexity
If a single threshold voltage is used in the comparator, then circuit complexity is reduced, but the ability to maintain stable output pulses under varying conditions is worsened
Solution Approach 1:
The patent segments the threshold voltage into two distinct levels: a first threshold voltage for comparing when the input signal is high, and a second threshold voltage for comparing when the input signal is low. This segmentation allows the comparator to maintain stable output pulses under varying conditions by using appropriate thresholds for each state, while the overall circuit structure remains relatively simple.
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 configuration enables the output pulse to maintain the same period as the input pulse, even with short pause periods, while preventing errors by adjusting charging and discharging currents based on capacitor voltage states, thus enhancing responsiveness to short pulse widths and periods.
Implementation Method 1
a charging and discharging circuit to charge a capacitor with charging current and discharge the capacitor with discharging current
Data Source
AI summary
A comparing circuit of the present invention includes: a charging and discharging circuit to charge a capacitor with charging current and discharge the capacitor with discharging current alternately in response to a switch of an input pulse signal; a comparator circuit to compare a capacitor-voltage (Csig) of the capacitor with a first threshold voltage (Vth1) and the capacitor-voltage (Csig) with a second threshold voltage (Vth2), which is higher than the first threshold voltage, to generate a pulse signal responsive to a result of this comparison, and to supply an output-signal generating circuit with the pulse signal to switch a level of an output pulse-signal; and a logical operation circuit to adjust a value of the charging current and a value of the discharging current by generating a signal that is based on the pulse signal and is to adjust the value of the charging current and the value of the discharging current of the charging and discharging circuit and supplying the charging and discharging circuit with the signal thus generated. This configuration makes it possible for the comparing circuit to maintain capability of preventing errors, and at the same time, improve in capability of outputting a pulse having a same period as that of an input pulse having a short pause period.