What Is a Contact Image Sensor?

Contact Image Sensor (CIS), used in scanners, is to arrange the photosensitive units closely and directly collect the light information reflected by the scanned manuscript. Because of its low cost and no lens group, the structure can be made. The cost of a more compact scanner is also greatly reduced.

Contact image sensor

Contact image sensor (Contact Image Sensor,

CIS consists of LEn light source array (LEolightsource), micro self-focusing rod lens array (Rod Lens array), photoelectric sensor array (CMOS image sensor array) and its circuit board, protective glass, interface, housing and other parts. The components of the CIS are all concentrated in the housing. The structure is compact, small in size and light in weight. The production of its main components requires micro-manufacturing processes. When the CIS works, the light emitted by the LED light source array directly hits the surface of the object to be scanned (prints, etc.), and the light reflected back from the surface is focused by the self-focusing rod lens array, and imaged on the photoelectric sensor array (generally MOS device) It is converted into charge and stored. The light intensity of different parts of the scanning surface is different, so the light intensity received by different position sensor units (ie, pixels of the CIS) is different. The illumination time (charge accumulation time) of each pixel is the same in each reading cycle. After the accumulation time is reached, the analog switch is controlled by the shift register to turn on sequentially, and the electrical signals of the pixels are output in the form of analog signals in order to obtain Analog image signal of a banknote.

As a new type of image sensor, compared with traditional image sensors (such as CCD charge-coupled devices), CIS has the following outstanding advantages:

(l) The light source, sensor, and amplifier of CIS are integrated into one. Its structure, principle, and optical path are very simple, with small size, light weight, compact structure, and easy installation; .5mmx232mm, weighs only 659g)

(2) There are no glass devices such as lamps and optical lenses in CIS, so the shock resistance is good;

(3) CIS uses a single clock drive / timing logic, which is simpler to control;

(4) The CIS transitions from the power-saving state to the working state very quickly, so the scanner using CIS does not need to warm up;

(5) CIS mostly adopts ceramic substrate, which has good temperature characteristics:

(6) The semiconductor manufacturing process is adopted, and the production cost is low.