Camera Sensors

Over the years, the security cameras are improved. Housings have gone from the behemoths of the 1970s and ’80s to the compact versions we see today. Images have gotten more obvious and have changed from black and white to color. However what has driven these remarkable changes? The cameras can’t get smaller unless the components inside the camera get smaller and use less power. Video can’t improve unless the image sensors and processors work better. An image sensor is the piece of camera that captures the light hitting the camera lens and turns it into electrical signals.

As light passes through your camera lens, it hits the image sensor. The sensor is made up for many little photosites (each photosite becomes a pixel in the video resolution), and the amount of light on each individual photosite determines how much light will be in each pixel of video. The light/dark sections of each pixel make up a cohesive image in the final video.

Image sensors for IP cameras are typically categorized into two main technologies: charge-coupled devices (CCD), complementary metal oxide semiconductor (CMOS). Both CCD sensor and CMOS sensor are actually using same kind of sensor called Photo diode. Even though analog CCD sensors are an old technology (around for over 30 years), requiring complex implementation systems and costly manufacturing processes, they are still the most common image sensor used in the security industry.

In CCD sensors, signal readout is an analog voltage, which is then converted to digital signals using additional, high-speed electronic components. Image quality is affected because signals are converted of analog to digital far away from the capture’s original point. CMOS image sensors utilize newer technology to record better HD resolution and fast-moving activity, and are found in the majority of IP new cameras.

CCD

CCD sensors generally record more resolution than CMOS sensors. Even though a CCD sensor has to spend more time and energy converting each pixel than an equivalent CMOS sensor, it can hold more across its surface. The noise level on a CCD sensor is inherently less than that on a CMOS sensor of the same size. In CCD sensor, colors tend to be more saturated and vibrant in contrast to those that are taken through a CMOS sensor.

CMOS

Each CMOS pixel is packaged with the circuitry to convert it to digital signal, thus each sensor takes up more space. CMOS sensor is become idle under 10 lux. The clutter on CMOS sensors reduces the light sensitivity of the chip. CMOS sensors have 10 times more fix pattern noise then CCD sensors.

CMOS sensor very useful for fast frame camera, the speed of frame can be as high as 400 ~2000 frame/sec. Early CMOS sensors were based on standard technology already extensively applied in memory chips inside PCs, for example modern CMOS sensors use a more specialized technology and the quality of the sensors is rapidly increasing. CMOS sensors also have a faster readout (which is advantageous when high-resolution images are need), lower power dissipation at the chip level.