The role and professional terminology of cmos image sensor

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

The role and professional terminology of cmos image sensor

Posted Date: 2024-01-27

CMOS image sensors are a common image capture device that use complementary metal oxide semiconductor (CMOS) technology to achieve light sensing and image acquisition.

It plays an important role in many application fields, including digital cameras, smartphones, surveillance cameras, medical imaging, industrial inspection, etc. The following are some professional terms related to CMOS image sensors:

1. Pixel: The smallest image unit of the image sensor. Each pixel corresponds to a smallest area in the image and is used to record the brightness and color of light.

2. Resolution: The level of image detail that the image sensor can achieve, generally expressed in terms of the number of horizontal pixels and the number of vertical pixels.

3. Image photosensitive element (Photosite): The photosensitive unit corresponding to each pixel in the image sensor. They are responsible for converting optical signals into electrical signals.

4. Image Noise: Unexpected random pixel changes in images, usually caused by manufacturing processes, environmental conditions, or electronic noise.

5. Dynamic Range: The range of brightness changes that the image sensor can capture, usually expressed as the ratio of the darkest and brightest parts.

6. Frame Rate: The number of image frames collected by the image sensor per second, usually expressed in frames per second (fps).

7. Pixel Size: The physical size of each pixel, usually in microns.

8. Sensitivity: The image sensor's ability to respond to light, usually expressed in terms of the number of photons corresponding to each pixel.

The above terms are common professional terms used in the research, design and use of CMOS image sensors. They help understand and describe the performance and characteristics of image sensors.

The role of cmos image sensor

The main function of the CMOS image sensor is to convert light into electrical signals, which are further processed and converted into digital images. It is usually composed of a large number of tiny photosensitive elements (pixels), each of which is responsible for sensing and recording the brightness and color of light.

The following are some of the main functions of CMOS image sensors:

Image capture: CMOS image sensors sense the intensity and color of light and convert light signals into electrical signals to capture and record images.

Digitization: After the sensor converts the optical signal into an electrical signal, the analog signal is converted into a digital signal through the internal analog-to-digital converter (A/D converter) to facilitate subsequent digital image processing.

Image processing: The circuit inside the CMOS image sensor can perform image enhancement, filtering, cropping, color correction, etc. to improve image quality.

Real-time transmission: The circuit inside the sensor can transmit the digital image to other devices in real time, such as a display screen, a memory card or a network transmission device, so that the image can be viewed or stored in real time.

Special functions: Some CMOS image sensors also have special functions, such as providing high dynamic range (HDR), low-light enhancement (Low-Light Enhancement) and high-speed continuous shooting to adapt to the needs of different scenes.

The function of the CMOS image sensor is to convert optical signals into electrical signals and process and convert them to achieve image capture, processing and transmission. It is widely used in various fields such as photography, videography, medical imaging and industrial testing.

The difference between cmos image sensor and ccd image sensor

CMOS (Complementary Metal-Oxide-Semiconductor) image sensor and CCD (Charge-Coupled Device) image sensor are two common image capture technologies. They have some obvious differences in their working principles, structures and characteristics.

1. Structure:

- Each pixel of the CMOS image sensor has its own amplifier and signal processing circuit, so the entire sensor chip integrates a large number of converters and control logic elements. This structure enables CMOS sensors to have high integration, low energy consumption, and relatively low manufacturing costs.

- CCD image sensors use one or more shift registers to control the output of all pixels, requiring an external circuit chip for signal amplification and processing. CCD sensors have a relatively simple structure, but require additional external circuit support for use.

2. Pixel design:

- CMOS sensor pixels are highly independent, and each pixel unit includes a photosensitive element, an amplifier and an A/D converter, so it is complex on the integrated circuit.

- Data transmission and processing are carried out between pixel units of CCD sensors through shift registers. All pixels share the same output circuit, so CCD has some advantages in image quality compared to CMOS.

3. Circuit complexity:

- Because each pixel of the CMOS sensor has an independent control and signal processing circuit, the overall circuit is more complex, but it is also more flexible.

- The overall circuit of the CCD sensor is relatively simple, but requires additional external circuitry for signal processing.

4. Power consumption and speed:

- Since each pixel of a CMOS sensor has its own amplifier and A/D converter, it usually consumes less power than a CCD sensor.

- CCD sensors usually have advantages in high speed and low noise, and are suitable for applications that require very high image quality.

There are some significant differences between CMOS image sensors and CCD image sensors in terms of structure, pixel design, circuit complexity, power consumption and speed. Therefore, in practical applications, choosing a suitable image sensor depends on specific application requirements and cost considerations.

Review Editor: Huang Fei

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