5 major differences between CCD industrial cameras and CMOS

CCD industrial phase and CMOS are two commonly used image process technologies. The main difference between them lies in the different transmission methods. People who have used cameras will definitely be familiar with these two terms, but they do not know much about the performance differences between them. A simple comparative explanation will be given here.

1. Noise difference:

   Since each CMOS photodiode needs to be matched with an amplifier, if calculated in terms of megapixels, millions of amplifiers are needed. However, amplifiers are analog circuits, and it is difficult to make every result consistent. CCD industrial cameras only need an amplifier placed on the edge of the chip. Compared with CMOS, its noise and sound are relatively reduced, which greatly improves the image quality.

2. Difference in power consumption:

   CMOS uses an active image acquisition method, and the charge generated by the photosensitive diode is directly amplified and output by the adjacent transistor; while CCD uses a passive acquisition method, and a voltage of 12~18V must be applied to move the charge in each pixel to the transmission channel. Therefore, CCD must design more precise power circuits and withstand voltage strength, which makes the power consumption of CCD much higher than that of CMOS. According to calculations, the power consumption of CMOS is only 1/8~1/10 of CCD.

3. Resolution difference:

   Since each pixel of CMOS is more complex than CCD, and its pixel size is difficult to reach the level of CCD, when we compare CCD and CMOS of the same size, the resolution of CCD industrial cameras is usually better than that of CMOS sensors.

   For example: a CCD camera with a pixel size of 4.40μm*4.40μm has a resolution of 1628*1236, while a CMOS camera with a pixel size of 5.2μm*5.2μm has a resolution of 1280*1024. The comparison results clearly show that with the same size, the resolution of CCD is higher than that of CMOS, which means that the imaging quality is better than CMOS.

4. Sensitivity difference:

   Because the CMOS signal is a charge signal in dot units, while the CCD is a current signal in row units. When reading signals, CMOS reads signals directly from dots, while CCD reads signals indirectly from rows. Therefore, when the pixel size is the same, the sensitivity of CMOS is lower than that of CCD.

5. Cost difference:

   Since CMOS is the same as the existing large-scale integrated circuit production process, peripheral facilities can be integrated into the sensor chip at once, greatly saving the cost of peripheral chips; CCD uses charge transfer to output data. As long as one pixel transmission fails, a whole row of data will not be transmitted normally. Therefore, controlling the yield rate of CCD is much more difficult than that of CMOS. Therefore, the manufacturing cost of CCD is relatively higher than that of CMOS sensors.