Apple patents circuit that measures light flicker from ambient sources
Apple describes a hardware circuit that measures how much ambient light flickers, such as from screens or lights. It uses a photodiode to capture light and a folding circuit to keep the signal within a safe range before converting it to digital data.
In the filing’s own words
An electronic device may have a sensor to measure ambient flicker. The sensor may be a sigma-delta converter. The flicker may be calculated based on the voltage output of the sigma-delta converter and the number of times the sigma-delta converter is triggered during a predetermined period, thereby reducing the voltage output. In particular, a fast Fourier transform (FFT) may be used on these values to determine the flicker. If desired, filtering and/or non-uniform sampling may be incorporated to avoid aliasing. Additionally or alternatively, a Lomb-Scargle spectral analysis may be used to prevent the attenuation of the measured flicker signals. As an alternative to using a sigma-delta converter to determine ambient flicker, a folding capacitive transimpedance amplifier (C-TIA) circuit or a circuit with an analog to digital converter and digital filter may be used to measure the ambient flicker.
What exactly they claim (claim 1)
1. A folding capacitive transimpedance amplifier circuit, comprising: a photodiode configured to generate charge in response to ambient light; an integrating capacitor that receives the generated charge; a low pass filter configured to receive and filter the generated charge; a folding circuit coupled to the integrating capacitor, wherein the folding circuit is configured to complete a fold into the integrating capacitor to reduce the generated charge on the integrating capacitor when the generated charge exceeds a threshold voltage; an analog to digital converter configured to convert the filtered generated charge and produce an output voltage; a timing and logic unit coupled to the low pass filter, the analog to digital converter, and the folding circuit; and a comparator that receives the generated charge from the integrating capacitor and compares the generated charge to the threshold voltage, wherein the timing and logic unit is configured to receive a signal from the comparator, and wherein the timing and logic unit is configured to clock the low pass filter, the analog to digital converter, and the folding circuit based on the signal from the comparator.
Facts
- Company
- Apple (Apple Inc.)
- Official title
- Electronic devices with ambient flicker detection
- Patent number
- US12730001B2
- Application number
- 18613515
- Filed
- Mar 22, 2024
- Granted
- Sep 8, 2026
- Inventors
- 6
- Claims
- 8
Classified under
G01J 1/4204 Physics & computingG01J 1/44 Physics & computingG01J 1/46 Physics & computingH03F 3/08 Electricity & electronicsH03F 3/087 Electricity & electronicsG01J 2001/446 Physics & computingMore from Apple in Chips & hardware
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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.