Sometimes mouse equip by wheel 6 for scrolling (motion of image on the screen), that is between two buttons.
Optical mouse. In the design of optical mouse mechanical contacting with a surface is not used, although it also rolls on it, as mechanical. Basic advantage of this technology consists in that there are not mobile parts in optical mise.Instead of sensors a miniature video camera is built-in, which fixes the state of surface and by its change "calculates", where a mouse was sent and with what speed.
Wireless mousecarry out connection with a computer through infrared port. Their lack is an obligatory "visual" contacting between a receiver-transmitter and by a device. Thus, freedom of relocation, as well as for a wire mouse, limited.
Possible use of radio channel. Such devices are not interfere with the receiver-transmitter closed by anything, but in this case there is large influence of obstacles on operation stability of device.
Fig. 6.7. Design of mechanical mouse
Scanners − devices, which enable to enter in the computer the "images" of pictures, passed as text, pictures, sliding seats, photo or other graphic information. Inspite of considerable quantity of different models of scanners, they are classified by a few signs (or by criteria): by the degree of transparency of image original, after the kinematic mechanism of scanner (by a design; by the mechanism of motion), by the type of image which is entered, by the features of the programmatic and hardware providing.
A determinative is a method of head moving of scanner and paper relative to each other. By this criterion all scanners are divided into two types: manual (hand-held) and desktop. However there are combinative devices which combined possibilities of desktop and manual scanners.
Manual scanners. The oldest type of scanners was developed at the end of 80th of XX century by the firms Logitech and Genius. In basis of their operation the process of registration of the reflected ray of light-emitting diodes is fixed from the surface of the scanned sheet − document.An user moves a scanner on the surface of document, and the reflected ray is accepted by means of lenses and converts into a digital form.The flow of data from a scanner by means of software is converted into digital representation. The different types of scanners register black and white colors or tints grey. The modern models of manual scanners can operate with a color in depth to 24 bits (16,8 million colors). The first models of manual scanners were connected to the computer by means of separate of interface board. Presently almost all devices of this class are connected to parallel port, depriving an user from setting in the computer of separate card which requires certain resources and adjustment.
Desktop scanners name a page, plane-table and even by autoscanners. Such scanners enable to display an image of size 8,5 õ 11 or 8,5 õ 14 inches. There are three types ofdesktopscanners: plane-table (flatbed), roll-up(sheet-fed) and projection(overhead) (fig. 6.8).
The basic distinction of plane-table scanners is that a scan head moves relative to a paper by means of step motor. The plane-table scanners are usually expensive enough, but, obviously, and the most productive devices. Outwardly they remind photocopying machines − "xerox". For the scanning of picture it is needed to open a closer of scanner, to lay the scanned sheet on a glass plate by an image downwards, whereupon to close a lid. The all further controlling of scanning process is carried out from the computer keyboard under the special program which is supplied together with a scanner. This design of device enables to scan not only separate sheets but also pages of magazine or book. The most popular scanners of this type are models of firm Hewlett Packard.
Operation of roll-up scanners is similar to operation of ordinary fax machine. The separate sheets of documents are stretched out through a device, due to what their scanning takes place. So, a scan head remains in place, and a paper moves relative to it. Clearly, that the scanning of pages of books and magazines is simply impossible in this case. Scanners are widely enough used in industries, associated with optical recognition of symbols ÎÑR (Optical Character Recognition). For comfort of work roll-up scanners are equipped by devices for automatic presentation of pages.
Fig. 6.8. Chart of desktop scanner
The third variety of desktop scanners is projection scanners, which are similar projection hardware or photographic enlarger. Document, that introduced, lay on a surface of scanning by an image upwards, a scanning block is here also above. The device of scanning moves only. The basic feature of these scanners is possibility of scanning of three-dimensional projections.
Distinguish two technologies of scanning − ÑÑD (Charge - Coupled Device) and Ñ²S (Contact Image Sensor).
ÑÑD.In these models the ray of light passes a long path after and even before scanning, as for the scanning of the coloured images it passes through colour filters for decomposition on red, green and blue components. The ray of light falls on an original, reflected from it and through the system of mirrors gets on photosensitive diodes, where converts into electric signals.
Signals act on ADC, where they are converted in signals, which are the pixels of original − black, white, tints of grey or color. Then this digital information is passed to the computer for further processing.
Ñ²S.In these scanners apply other type of receiving element − Ñ²S (Contact Image Sensor). This element consists of sensors line which directly perceive a light thread from an original, thus the line of sensors has a width which equals to the width of working area of scanner, and the optical system (mirrors, prisms, objective) is absence.
Interfaces of desktop scanners.All modern models of desktop scanners use for connecting to the computer the interface − parralel port or USB.
Parallel port is an interface which is applied in the scanners of low level. As there is parallel port in all computers, then scanners with this interface are the most universal. However scanners with the parallel connecting have a row of shortcomings. At first, not always it is succeeded to provide normal operation of scanner and printer or other devices, connected simultaneously to parallel port. Secondly, speed of data transfer is limited to speed of parallel port, id est about 1 Ìb/s. Finally, if a scanner "scans", then at this time it is impossible to do any operations on a computer, it does not react on external irritants. This type of connecting of scanner it is possible to use only then, if on any reasons other interfaces it is impossible to use.
Interface USB. Lately large enough popularity is used by the bus USB. This type of connecting most do for the untrained user − it is needed only to connect a cable, and the system will set necessary software independently. Speed of data transfer to port USB arrives 12 Ìb/s.
Video cameras. Modern video cameras are complex technical products, but they are simple enough in the use.
For the analog videotape recording apply such formats of cassettes.
Format VHS. Advantages: possibility of record on an ordinary cassette with the width of film 12,6 mm, in particular revision of the shooted material without using of additional devices and rewriting;most duration of record on the cassette − 240 min (480 min in the mode of Long Play with the corresponding loss of quality);possibility of the use of video camera as a portable videoplayer for the show of not only the shooted material but also purchased or written video films.
Shortcomings: not high quality of image (240 lines are for horizontals); a considerable decline of quality during the printing-down of the shooted material; high energy consumption; large overall sizes and mass; high enough cost.
Format VHS-Ñ (VHS - Ñîòðàñt). The camers of this format have analogical property of recordable signal, but a record is conducted on a compact-cassette with the size of film 12,6 mm.
Advantages: possibility of recreation on an ordinary videoplayer with using of the special adapter for a cassette (usually included in a complete set, but if necessary is at a sale); an energy consumption, overall sizes and mass is less comparatively with VHS-cameras; the most low prices are among amateur video cameras.
Shotcommings: not high clearness of image; the considerable worsening of quality is during a printing-down; small duration of record − 90 min in the usual mode and 180min in Long Play; mainly record only of monosound.
Format S-VHC (Sèðår - VHS). Advantages: the best quality of record (400 ÷ 420 lines for horizontals); less losses of quality during rewriting, than in VHS, VHS-C; a presence of disjoint S-Video (in most camers),that provides more high-quality signal transfer for a record and recreation;record of stereosound; possibility of the use of cassettes VHS (with the corresponding decline of quality of record).
Shortcommings: relatively high cost; large overall sizes and mass; impossibility of recreation of the videotape recording on usual VHS-videoplayer or videorecorder (a viewing is possible only after connecting to ÒV of video camera or S-VHS-videorecoder); small duration of record − 90 min in the usual mode and 180 min in Long Play.
Format S-VHC-Ñ (Super - VHS - Compact). Video cameras of this format are a small variant of S-VHC-format with the use of compact-cassette.
Advantages: the improved quality of record (400 ÷ 420 lines for horizontals); less losses of quality during rewriting, than in VHS, VHS-C; presence of socket S-Video (in most camers), that provides to the high-quality signal transmit for a record and recreation; record of stereo sound; possibility of the cassettes use VHS (with the corresponding decline of record quality); mass, overall sizes and energy consumption, is small comparatively with S-VHC.
Limitation: small duration of record − 90 min in the usual mode and 180 min in Long Play; relatively high cost of video cameras.
Format Video 8. The camers of this standard use the own format of video cassettes with the width of film 8 mm (from here and the name of format).
Advantages: large duration of record on one cassette − it is about 120 min in the usual mode and 240 min in the mode of Long Play; possibility to keep the shooted films for a long time due to the use of metallized films; relatively not high cost of cameras; small mass; many cameras write down stereo sound.
Limitation: the recreation of records is possible only after connecting of camera to ÒV or use of videoplayer/videorecorder of format Video 8; not high quality of image −240 ÷ 250 lines for horizontals (a firm Sony produced the improved variant of this format − Video 8ÕR with increased discrimination to 280 lines); the considerable worsening of quality during rewriting.
Format Hi 8. Video cameras of standard Í³8 use improved comparatively with Video8standard of record and cassette with more high-quality film (with the same sizes and width).
Advantages: the improved quality of record (380 ÷ 420 lines are for horizontals). A firm Sony produced the improved model − Í³8ÕR with the increased discrimination − about 440 lines for horizontals, by the less level of obstacles to coloured and brightness; by increased duration of record − 180 min in the usual mode and 360 min in the mode of Long Play; by the record of stereo sound (in most chambers); by presence of disjoint S-Video (in most cameras); by possibility of recreation of cassettes of format Video8 (with the corresponding decline of quality of image).
Analog video cameras are though widespread, but presently they unviable, that is why replaced by digital cameras.
Format Ì³ï³ DV. Advantages: record of picture-sound in the digit state;absence of quality losses during rewriting;possibility of the signal direct transfer to computer;presence of sockets S-Video, RÑÀ, DV input/output; miniature sizes of video cameras and cassettes (66 õ õ 48 õ a 12 mm with the width of film 6,35 mm); for the increase of bit density a compression is used with averagefactor5,1, that enables to attain quality of record, whichsmall yields professional Âåtàñàò SÐ; a discrimination almost answers televisional (about 500 lines for horizontals); a digital record isalmost deprived noises of coloured, peculiar analog record; high quality offilm enables to keep records for a long time; presence of video cassettes with memory (only for the video cameras of firm Sony)for the further editing of record of titles, maintenance of list of records on a cassette with further fast access to chosensegment or to the snapshot;digitising of sound is possible in two variants: 2channels by 16 bits/48 kHz or 4channelsby12 bits/32 kHz. The first variant enables to attain maximal quality of sounding (level of musical ÑD), second − reserves 2 channels for imposition ofaudio and vocal accompaniments in the process of editing.
Limitations: impossibility of recreation of records on ordinary video-players and videorecorders (only after connecting of video camera to ÒV oruse of professional DV-videorecoder); very high cost of video cameras and video cassettes; small duration of record on one cassette − 60 ÷ 80min in the usual mode and 90÷120 min in the mode of Long Play.
Format D³g³tàl 8. Video cameras of format Digital 8 were created for reduction of prices and distribution of digital video.
Advantages: digital record of sound and image with a discrimination about 500 lines for horizontals;digitising of sound is possible in two variants: 2 channelsby 16 bits/ 48 kHz or 4 channels by 12 bits/32kHz. The first variant enables to attain maximal quality of sounding (level of musical ÑD), second − reserves 2 channels for imposition of sound and vocal accompaniments during editing;possibility of cassettes using of Hi 8, Video 8 and a recreation of records) of these formats, and also digitising of analog records, is through analog inputes.
Limitations: small duration of record on one cassette − 60 ÷ 80 min in the usual mode and 90÷120 min in the mode of Long Play.
Newest format of video cameras Ì³ñrî ÌV. Firm Sony announced appearance on market a new generation of digital video cameras, that use format of record "Ì²ÑRÎ ÌV". Ì²ÑRÎ ÌV − first, developed by a firm Sony, format of record for amateur video cameras, that uses the standard of compression ÌÐÅG2.
It considerably simplifies placing of the shooted by videocamera material in a Internet network, as this open standard has an enormous amount of different additions. At transfer speed 12 Ìb/s Ì²ÑRÎÌV has an almost twice less data flow, than DV, that gives the considerable economy of place on the hard disk of the personal computer without the quality loss of image during a record.
A lens forms an image on the light-recording device − videocon or charge coupling device (CCD). Exactly this device provides the receipt of image. The matrix of CCD consists of large amount of cells − pixels. The more pixels are contained by the matrix of CCD, the more high-quality will be an image.
A video camera has a high-quality lens with variable focal distance, which can be changed both by hand and by means of electric drive. The change of focal distance enables to set the plan of shooting. Multipleness of focal distance (ratio of maximal focal distance to minimum) which is arrived by optical tools, equals to 10 ÷ 20, but the digital increase of multipleness is used.
The matrix of CCD is characterized by certain light-sensitivity, that is why video cameras lens has diaphragm, which enables to regulate the size of light flow which gets on a matrix depending on the object illumination. A shutter enables to choose the size of display (usually it takes place automatically). Therefore at a shooting a frequency of frames change is provided 25 frames by 1 s. The size of exposure and frequency of frames change are interconnected, that it follows to take into account in case of manual choice of exposure (at the choice of exposure over 1/25 s the noted frequency of frames change can be not provided).
The sound highway of video camera (mono- or stereophonic) does not differ in the main from a sound highway audio- or videorecorder. Video cameras have a built-in microphone, and some − nests for plug-in of external microphones. On many video cameras monochrome or coloured displays are set, that enables to choose the plan of object of shooting, and also in the mode of videorecorder to look over the shooted material. On a display the parameters of video filming are displayed also − date, time, degree of battery discharging, chosen parameters of shooting.
6.5. OUTPUT DEVICES − PRINTERS, PLOTTERS, PROJECTORS
Devices of output on a paper transmitter divide into printers, or print media, and plotters, or graphic devices. Consider that printers are intended mainly for the output of text (although can send to the printer graphic images), and plotters − for the output of graphic arts (it is although possible to print out texts also). Classification of devices of printing out on a paper carrier it is resulted in a table. 6.2.
The order of information output determines the volume of information, that is transmitted from buffer memory of peripheral unit for printing one memory access cycle.
The mechanical devices of output have shock operation principle − in the printers an image is recreated on a paper due to ink ribbonor paint which is coated on the surface of printing element.At the use of sensitive paper its color changes without carrier-paint.
Table 6.2. Classification of output devices on a paper carrier
|Order of data output||A method of image registration at output||Principle of symbols forming on a transmitter||Working format||Design||Operation with a pan||Internal data output|
|Symbol||Mechanical||Character display||Mean-format||Uses a paper clamp and motion of pen||Roundabout is used||Vectorial|
|String||Unmechanical||Fullsymbol||Large-format||Drum||Roundabout is not used||Bit-mapped|
In graphic devices for fixing of image use pencils, markers, ball point pens.
In unmechanical devices outputs thephysical and chemical processes are used which arise up in the special transmitters at the action of different energy sources (light flow, magnetic-field, electrostatic voltage, laser ray). They are such types: electrosensitive, magnetic- (or ferro-) graphic, electrostatic, thermal and ink-jet.
The Fullsymbol devices of output have the limited set of symbols, that printed-in on a paper.The printing machines in which a character set is set once and for all during their making belong to such devices.
Character devices enable to print-out any images. To such output devices a plotters belong, and also mechanical printers of matrix type and all unmechanical printers.
After a working format – differ three types of output devices which have formats accordingly: À4 and A3; À2 and À1 and anymore À0.
The drum output devices are differed from previous design that a paper sheet is placed on a drumthe rotation of which replaces the horizontal moving of sheet. In plane-table output devices apaper is immobile, and the outputhead moves in both directions.
Distribution of output devices by operation principle with pens is executed only for plotters. Plotters which use a roundabout, have the special storage for pens of different color, which is called roundabout and is placed one side from a paper sheet. If there is necessity of pen replacement, the output head moves to the roundabout, changes a pen and returns on previous a place for continuation of output. If a roundabout is not used and every pen is kept in the head, then the additional moving does not take place.
The vectorial output devices are used for presentation of output data, as a set of vectors in the system of coordinates X and Y.
The raster output devices are applied for presentation of images as a raster matrix, whichduring an output is scanned line after a line, that is why an image is consistently formed of points. Theunmechanical output devices operate by such principle.
Most widespread are matrix and electrophotographic printers, ink-get and thermal devices of output on a paper transmitter.
Matrix printers.Operation principle of matrix printing devices is based on that a necessary image is recreated of a set of separate points which are coated on a paper by a corresponding method. So, in the coloured matrix printers a needles of output head "humer in" an ink from a ribbon straight in a paper (fig. 6.9).
Unlike usual monochrome devices, in last case use a multicoloured ribbon. Control system of these printers is charged with not only for a certain needle but also for the colors of ribbon.
Fig. 6.9. Design of output
head of ninestylus printer:1 – stand - alone electrodrives for every needle; 2 − needles
Electrographic technology.The example of output device which uses ålectrographic technology is a laser printer, or plotter the chart of which is represented on fig. (6.10).
Basic parts of laser printer are a photoconductive drum 4, semiconductor laser 1 and precision optomechanical system 2, that moves the ray. A laser forms electronic image on light-sensitive photoreception coverage of drum consistently for Fig. 6.10. Laser printer: 1 − source of laser ray which is switched by a controlling microprocessor; 2 – six-sided mirror which sweeps a ray in a line; 3 − mirror of displaying; 4 − billow which gives from the special container coloring matter (toner) on drum; 5 − printing drum; 6 − cleaner of roll from a toner; 7 − block of image fixing.
every colortoner (ÑÌYÊ).
Before the acceptance of image line a drum is charged with the help of net which surrounds it. A net is under voltage, which results in appearance of ionized medium round a drum which charges it. A ray, getting on a drum, discharges some areas of drum. After forming of image line a step motor returns a drum for forming of next line.
If an image on a photosensitive layer is fully built, a sheet which is given is charged so that toner from a device 5 will get on a drum, and then attracted from a drum to the paper. After this image fastened on it due to heating of particles of toner to the melting temperature in a block 7. A toner contains a fusible matter − polymer or resin. At heating and increase of pressure powder is fused and united with a paper. The final fixing of image is carried out by the special rollers which press a molten toner to a paper.
Jetting technology presently is most widespread for realization of colour output devices. The simplified chart of jetting output device is represented on fig. 6.11.
Fig. 6.11. Chart of jet device
An ink comes in emitter under pressure from a nozzle. The block of acceleration electrifies and accelerates a drop thread. Thus each of drops receives a certain electric charge. In CB a flight path of drops changes by a help of deflection electrodes, and also there is turning on and off of stream. Thus the block of synchronization synchronizes operation of other devices.
The jet devices of output divide on the device of continuous and discrete action. The last, in turn, divide into two categories: with heating of ink ("bubble" technology) and with application of piezoeffect action.
Operation principle of device by technology of continuous action is based on that the stream of ink, which is constantly produced from the nozzle of printing head, gets or on a paper (for causing of image), or in the special transceiver, from where an ink again gets in a general reservoir. In a working chamber an ink is given by a micro-pump, and by element which predetermines its motion, usually there is piezosensor. However this operation principle is used presently in some of output devices.
For realization of discrete method with heating of ink there is a little element of heating in every nozzle of printing head, for example thin-film resistor. During passing of current through a resistor last for a few microseconds heated to the temperature about 500 °Ñ and gives the distinguished heat directly to ink. An ink steam bladder, which appears in the process of the sharp heating, wants to push out a drop of liquid ink through the outlet of nozzle. As after breaking contact a resistor cools off quickly, then a steam bubble, decreasing in sizes, "sucks" through an nozzle inlet a new portion of ink, which takes seat of ejected drop (fig. 6.12).
Fig. 6.12. Chart of thermo-jet head:
1 − nozzle plate; 2 − card; 3 − corps; 4 − reservoir for ink; 5 − microresistor; 6 − the nozzle let
Another method for a nozzle controlling by discrete technology is based on the action of diaphragm, connected with a piezoelectric element. Piezoeffect consists in deformation of piezocrystal under the action of electric-field. Change of piezocrystal sizes, placed from one side of the nozzle outlet and constrained with diaphragm, predetermines throwing out of ink drop and lug of new ink portion through inlet. Nozzles (channel lets) on the printing head of jet output devices, through which an ink is spraied, answer to the "shock" needles of matrix printers.
As a size of every nozzle considerably less, than diameter of needle, and an amount of nozzles can be more, then the got image in theory must be more clear. Unfortunately, in practice it is arrived at only in case of application of special link.
Thermal technology. Operation principle of output device with thermal transfer consists in that a thermoplastic coloring matter, deposited on the thin lining, gets on a paper exactly in a that place, where the proper temperature − about 70 ÷ 80 °Ñ is ensured by the heating elements of printing head. Structurally such method of printing is simple enough, besides it provides almost noiseless operation. For causing of the coloured image it is needed three or four passage-ways: by once for primary colors and one time at the use of black that increases duration of printing accordingly. Surely, the special paper is needed for this purpose.
To thermal printers the printers of sublimations belong also, as for transference of image on the paper they use heating.
Sublimation of imager. At such method for a generation the imager is transfered from a ribbon by means of thermohead heating by a different temperature. Depending on a temperature there is transference of greater or less amount of transmitter, due to what the different tints of color appear. Such method of sublimation is the slowest. For printing use the special paper with coverage, in which imager accumulates.