Comparison Avision AV332U vs Fujitsu fi-7140

— CIS, abbreviation for "Contact Image Sensor" — contact image sensor. The simplest type of optical element: it is a line across the entire width of the scanner's working space, on which photocells that read the image and LEDs that provide illumination are located in a row. They are inexpensive and take up little space, which, accordingly, makes the scanners themselves cheaper and smaller. On the other hand, CIS sensors have a shallow depth of field, and even small bumps in the scanned image can be out of focus. However, in general, they are quite suitable for both personal and not too complex professional tasks.

— CCD, short for "Charge-Coupled Device" — a charge-coupled device. A much more complex design than CIS, includes a fluorescent lamp, lens and mirror. CCD scanners are larger, heavier and much more expensive than their counterparts in CIS. On the other hand, this type of optical element provides high-quality colour reproduction and a good depth of field, coping well with complex-shaped media. Therefore, advanced professional scanners are usually equipped with a CCD.

— CMOS. The abbreviation for "Complementary Metal-Oxide-Semiconductor" is a complementary metal-oxide-semiconductor structure (the designation CMOS is also used in Russian). A key feature of CMOS sensors is that they capture the scanned image as a whole, similar to photography (and not...line by line, as in other types of optical elements). In fairness, it should be noted that the "instantaneous" scanning does not give a tangible advantage in speed, because. processing the captured image takes quite a long time. However, this feature is extremely useful in cases where it is difficult to ensure the immobility of the scanned material and/or uniform movement of the optical element relative to this material. Such situations often arise when working with book and handheld scanners (see "Type"), so CMOS elements are most popular in such devices.

The maximum image size that the scanner can process at one time, both horizontally and vertically. You should pay attention to this parameter if you need the exact dimensions of the scanner's working area, down to a millimetre: although standard formats are used to designate these dimensions (see "Format"), in fact the dimensions may differ from them.

Under the internal colour depth is meant the number of shades of the image that the scanner itself can recognize; it should not be confused with external depth, which is the amount of hue transmitted to the computer (see below). Colour depth is expressed as the number of bits of information used to encode data about each colour. The total number of colour shades in this case is 2 to the power of n, where n is the colour depth. So, a 24-bit scanner recognizes 16.7 million colours — which is more than one and a half times more than the human eye, and quite enough for simple everyday tasks. In more advanced professional models, colour depth can reach 96 bits. Although the characteristics of the image transmitted to the computer are described by the external colour depth (which can be less than the internal colour depth), the internal depth, however, also affects its quality: other things being equal, a scanner with a higher internal depth provides more accurate colour reproduction.

The maximum number of pages that the scanner can process per day without overloading and the negative consequences associated with them. Most often indicated for A4 format. Even the most modest models of modern scanners have duty cycles measured in dozens of pages, which is quite enough for simple everyday tasks. Therefore, you should pay attention to this parameter if you have to scan numerous materials every day.

The maximum number of sheets of standard weight (80 g/m²) paper that can be placed in the scanner's auto feed system at a time. These systems are similar to those installed in printers: a stack of sheets is installed in a special tray, and each of them is fed in turn for scanning. It is worth paying attention to models with this function if you often have to work with numerous documents: you will not need to monitor the process and manually feed sheets — just load the originals into the automatic document feeder and press the button. Many document feeders, some flatbeds, and almost all combination scanners have an ADF (see "Type"). It works, however, only with separate sheets and cannot cope with larger media.

Availability of duplex scanning function in the device. Duplex scanning in this case means such an operating mode in which the scanner simultaneously captures an image from both sides of the processed medium (sheet of paper). The convenience of this feature is obvious: the media does not have to be turned over to scan each side separately, and the processing time is significantly reduced. Double-sided scanning is found mainly in the models of traction or combined type (see above), however, there are also flatbed scanners with this capability.

The scanner has its own display. Such displays can vary from simple indicators that display a minimum of service information (selected mode, work process, some errors, etc.) to full-colour touch screens that significantly expand the capabilities of the device. Anyway, the display makes the operation of the scanner more convenient and intuitive.

The maximum noise level produced by the scanner during operation. Theoretically, the lower this parameter, the more comfortable the use of the device, however, the vast majority of scanners have a noise level much lower than the general sound background in a small office (this background is 40-50 dB). Therefore, it is worth paying special attention to the noise level if you plan to use the device at home at a later time, or in other environments where even a slight noise may be undesirable.

The maximum power consumed by the scanner during operation. The higher the power, the more energy the scanner consumes, but this only applies to the scanning process itself — in standby mode, power consumption is negligible. And even at the peak in most models, the power is so low that in fact this parameter has practically no effect on electricity bills and is more of an auxiliary value (for example, it is used to calculate the total power of devices connected to an uninterruptible power supply).