CIS (Contact Image Sensor) and CCD technology appear almost at the same time. The photosensitive material used is generally the cadmium sulfide we use to make photoresistors. It is easy to make a long array, and the production cost is only 1/3 of the semiconductor isolation CCDs were mainly used in low-end black-and-white hand-held scanners and facsimile machines. Due to their large size, they were unable to use lens imaging, and they could only rely on close targets to identify targets. Therefore, the highest optical resolution was achieved. 200dpi, around 1994, with the colorization and high precision of the scanner, the contact-type light-sensing device itself has large noise, small dynamic range, and low-precision defects are undoubtedly exposed, quickly disappearing from the scanner market. In the following years, we could only see it on the fax machine.
The turnaround took place in 1998. At that time, the international scanner market was very competitive. Major manufacturers used the magic weapon of price reduction, resulting in the loss of scanner manufacturers. Some manufacturers began to relocate contact-sensitive light-sensing devices. After being improved, their resolution reached 600 dpi, and then they were crowned with the CIS technology name, and they were introduced to the market with the appearance of new technologies. They actually achieved considerable success. However, in terms of performance, there are serious congenital defects in contact-sensitive devices. First of all, due to the inability to use the lens, they can only scan close to the manuscript. In fact, the resolution is far below the nominal target. At the same time, the cadmium sulfide photo-resistor itself has a large leakage current. The interference between the photosensitive cells is severe, further reducing the sharpness, and since it is impossible to manufacture three parallel photosensitive cells and simultaneously achieving three-color scanning, the contact-type photosensitive device cannot use the commonly used cold cathode lamp and has to use light The array of diodes (LEDs) serves as a light source, which is relatively poor in light color and light uniformity. Moreover, since the LED array is composed of hundreds of light emitting diodes, once a single damage is caused, the whole array is scrapped. The life span of the product is relatively short, and the temperature coefficient of the light sensing device is large, and the ambient temperature changes to the scanner. The results of the scan have a great effect, so if you want a stable scan, it is best to work in a room with constant temperature.
The turnaround took place in 1998. At that time, the international scanner market was very competitive. Major manufacturers used the magic weapon of price reduction, resulting in the loss of scanner manufacturers. Some manufacturers began to relocate contact-sensitive light-sensing devices. After being improved, their resolution reached 600 dpi, and then they were crowned with the CIS technology name, and they were introduced to the market with the appearance of new technologies. They actually achieved considerable success. However, in terms of performance, there are serious congenital defects in contact-sensitive devices. First of all, due to the inability to use the lens, they can only scan close to the manuscript. In fact, the resolution is far below the nominal target. At the same time, the cadmium sulfide photo-resistor itself has a large leakage current. The interference between the photosensitive cells is severe, further reducing the sharpness, and since it is impossible to manufacture three parallel photosensitive cells and simultaneously achieving three-color scanning, the contact-type photosensitive device cannot use the commonly used cold cathode lamp and has to use light The array of diodes (LEDs) serves as a light source, which is relatively poor in light color and light uniformity. Moreover, since the LED array is composed of hundreds of light emitting diodes, once a single damage is caused, the whole array is scrapped. The life span of the product is relatively short, and the temperature coefficient of the light sensing device is large, and the ambient temperature changes to the scanner. The results of the scan have a great effect, so if you want a stable scan, it is best to work in a room with constant temperature.
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