Computer Monitor

    

     

         A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD), while older monitors use a cathode ray tube (CRT).

           The size of an approximately rectangular display is usually given as the distance between two opposite screen corners, that is, the diagonal of the rectangle. One problem with this method is that it does take into account the fact that when a rectangle with a given length to its diagonal, becomes more rectangular, and less square (its aspect ratio increases), and at the same time its diagonal remains the same, then the area of the rectangle decreases. That is, given the same diagonal, the area of the display decreases if its aspect ratios increases. For example, a 4:3 21 in (53 cm) monitor has an area of about 211 sq in (1,360 cm2), while a 16:9 21-inch widescreen has about 188 sq in (1,210 cm2).
                  This method of measurement is inherited from the method used for the first generation of CRT television, when picture tubes with circular faces were in common use. Being circular, only their diameter was needed to describe their size. Since these circular tubes were used to display rectangular images, the diagonal measurement of the rectangle was equivalent to the diameter of the tube's face. This method continued even when cathode ray tubes were manufactured as rounded rectangles.
                  Another problematic practice was using the size of a monitor's imaging element, rather than the size of its viewable image, when describing its size in publicity and advertising materials. Especially on CRT displays, a substantial portion of the imaging element is concealed behind the case's bezel or shroud in order to hide areas outside the monitor's safe area due to overscan. These practices were seen as deceptive, and widespread consumer objection and lawsuits eventually forced most manufacturers to instead measure viewable size.

Contact image sensor

Contact Image Sensors (CIS) are a relatively recent technological innovation in the field of optical flatbed scanners that are rapidly replacing CCDs  in low power and portable applications. As the name implies, CISs place the image sensor in near direct contact with the object to be scanned in contrast to using mirrors to bounce light to a stationary sensor, as is the case in conventional CCD scanners. A CIS typically consists of a linear array of detectors, covered by a focusing lens and flanked by red, green, and blue LEDs  for illumination. The use of LEDs allows the CIS to be highly power efficient, allowing scanners to be powered through the minimal line voltage supplied via a USB  connection. CIS devices typically produce lower image quality compared to CCD devices; in particular, the depth of field is greatly limited, which poses a problem for material that is not perfectly flat. However, a CIS contact sensor is smaller and lighter than a CCD line sensor, and allows all the necessary optical elements to be included in a compact module, thus helping to simplify the inner structure of the scanner. With a CIS contact sensor, the scanner can be portable, with a height of only around 30 mm. CIS is a both a key component of, and widely used in, scanners (especially portable scanners), electrographs, bar code readers and optical identification technology.

Mother Board

        Motherboard is the central printed circuit board in many modern computers  and holds many of the crucial components of the system, while providing connectors for other peripherals. The motherboard is sometimes alternatively known as the main board, system board, or, on Apple computers, the logic board.It is also sometimes casually shortened to mobo.
        Prior to the advent of the microprocessor, a computer was usually built in a card-cage case or mainframe with components connected by a backplane  consisting of a set of slots themselves connected with wires; in very old designs the wires were discrete connections between card connector pins, but printed circuit boards soon became the standard practice. The Central Processing Unit, memory and peripherals were housed on individual printed circuit boards which plugged into the backplane.
        During the late 1980s and 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard. In the late 1980s, motherboards began to include single ICs Capable of supporting a set of low-speed peripherals: keyboard, mouse, floppy disk drive, serial ports, and parallel ports. As of the late 1990s, many personal computer motherboards supported a full range of audio, video, storage, and networking functions without the need for any expansion cards at all; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as a separate component.
     The early pioneers of motherboard manufacturing were Michronics, Mylex, AMI, DTK, Hauppauge, Orchid Technology, Elitegroup, DFI, and a number of Taiwan-based manufacturers.
     The most popular computers such as the Apple II and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse-engineering and third-party replacement motherboards. Usually intended for building new computers compatible with the exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment.
     The term mainboard is archaically applied to devices with a single board and no additional expansions or capability. In modern terms this would include embedded systems and controlling boards in televisions, washing machines, etc. A motherboard specifically refers to a printed circuit with the capability to add/extend its performance.