How a Modern Camera Sensor Captures Light and Converts It to Data

This patent describes a camera sensor technology that combines light-capturing elements with a special circuit to read out the image data quickly and efficiently, all on a single chip.

What it covers

The patent describes an imaging device, like a digital camera sensor, built on a single silicon chip using a common manufacturing process (CMOS). Each tiny picture element, or "pixel cell," has a photogate (Claim 1) that collects light and turns it into an electrical charge. This charge is then moved within the pixel by a small charge coupled device (CCD) section (Claim 1) to a sensing node. From there, a CMOS readout circuit (Claim 1) with an output field effect transistor (Claim 1) converts the charge into a voltage signal that can be read by the camera. For example, when light hits a pixel, the photogate gathers the light's energy, which is then quickly shifted by the CCD part to the readout circuit, allowing the camera to process the image.

What it doesn't cover

• —Image sensors that use only traditional CCD technology for both charge collection and readout across the entire chip.
• —Sensors where the charge is read out directly from the photogate without an intermediate charge coupled device section within the pixel.
• —Image sensors that do not use a complementary metal oxide semiconductor (CMOS) circuit for the pixel's readout.
• —Sensors that rely on different charge accumulation mechanisms other than a photogate.
• —Pixel designs where the charge transfer and readout are handled by entirely separate, off-chip components.

The clever bit

The innovation was integrating a small, efficient charge transfer mechanism (a CCD section) within each pixel of a CMOS sensor, allowing for faster and lower-noise readout than previous CMOS designs, while still benefiting from the cost and integration advantages of CMOS manufacturing.

Why it matters

This patent is foundational for the development of modern CMOS image sensors. These sensors became a key alternative to older CCD sensors, offering advantages in power consumption, manufacturing cost, and integration with other electronics. The technology enabled the widespread adoption of digital cameras in everything from smartphones to webcams and professional cameras.

Real-world examples

• 1.Smartphone camera sensors (e.g., Apple iPhone, Samsung Galaxy)
• 2.Digital single-lens reflex (DSLR) and mirrorless camera sensors
• 3.Webcams
• 4.Security cameras
• 5.Automotive cameras