Dot matrix

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Dot matrix pattern woven into fabric in 1858 using punched cards on a Jacquard loom. The Childrens Museum of Indianapolis - Jacquard coverlet - overall.jpg
Dot matrix pattern woven into fabric in 1858 using punched cards on a Jacquard loom.
Close-up view of dot matrix text produced by an impact printer. Dot printer ASCII0x7C+.png
Close-up view of dot matrix text produced by an impact printer.
"Bling Bling": Dot matrix-style skywriting. Bling-Bling Skywriting David Shankbone.jpg
"Bling Bling": Dot matrix-style skywriting.

A dot matrix is a 2-dimensional patterned array, used to represent characters, symbols and images. Every type of modern technology uses dot matrices for display of information, including mobile phones, televisions, and printers. They are also used in textiles with sewing, knitting and weaving.

Contents

An alternate form of information display using lines and curves is known as a vector display, was used with early computing devices such as air traffic control radar displays and pen-based plotters but is no longer used. Electronic vector displays were typically monochrome only, and either don't fill in the interiors of closed vector shapes, or shape-filling is slow, time-consuming, and often non-uniform, as on pen-based plotters.

In printers, the dots are usually the darkened areas of the paper. In displays, the dots may light up, as in an LED, CRT, or plasma display, or darken, as in an LCD.

Usage in computers

Although the output of modern computers is generally all in the form of dot matrices (technically speaking), computers may internally store data as either a dot matrix or as a vector pattern of lines and curves. Vector data encoding requires less memory and less data storage, in situations where the shapes may need to be resized, as with font typefaces. For maximum image quality using only dot matrix fonts, it would be necessary to store a separate dot matrix pattern for the many different potential point sizes that might be used. Instead, a single group of vector shapes is used to render all the specific dot matrix patterns needed for the current display or printing task.

All points addressable

All points addressable (APA), or pixel addressable, in the context of a dot matrix on a computer monitor or any display device consisting of a pixel array, refers to an arrangement whereby bits or cells can be individually manipulated, as opposed to rewriting the whole array, or regions such as characters, every time a change is needed. [1] [2]

Generally, text modes are not all-points-addressable, whereas graphics modes are. [2] With the advent of more powerful computer graphics hardware, the use and importance of text-only display modes has declined, and with graphics modes it is generally taken for granted that they are all-points-addressable.

Usage in printers

The process of doing dot matrix printing can involve dot matrix printers, both for impact and non-impact printers.

Almost all modern computer printers (both impact and non-impact) create their output as matrices of dots, and they may use

Except for impact dot matrix printers, it is not customary to call the others by that term. [3]

Printers that are not but what the New York Times calls a "dot-matrix impact printer" are not called dot matrix printers. Impact printers survive where multi-part forms are needed, as the pins can impress dots through multiple layers of paper to make a carbonless copy, for security purposes.

As an impact printer, the term mainly refers to low-resolution impact printers, with a column of 8, 9 or 24 "pins" hitting an ink-impregnated fabric ribbon, like a typewriter ribbon, onto the paper. It was originally contrasted with both daisy wheel printers and line printers that used fixed-shape embossed metal or plastic stamps to mark paper.

All types of electronic printers typically generate image data as a two-step process. First the information to be printed is converted into a dot matrix using a raster image processor, and the output is a dot matrix referred to as a raster image, which is a complete full-page rendering of the information to be printed. Raster image processing may occur in either the printer itself using a page description language such as Adobe Postscript, or may be performed by printer driver software installed on the user's computer.

Early 1980s impact printers used a simple form of internal raster image processing, using low-resolution built-in bitmap fonts to render raw character data sent from the computer, and only capable of storing enough dot matrix data for one printed line at a time. External raster image processing was possible such as to print a graphical image, but was commonly extremely slow and data was sent one line at a time to the impact printer.

Depending on the printer technology the dot size or grid shape may not be uniform. Some printers are capable of producing smaller dots and will intermesh the small dots within the corners larger ones for antialiasing. Some printers have a fixed resolution across the printhead but with much smaller micro-stepping for the mechanical paper feed, resulting in non-uniform dot-overlapping printing resolutions like 600×1200 dpi.

A dot matrix is useful for marking materials other than paper. In manufacturing industry, many product marking applications use dot matrix inkjet or impact methods. This can also be used to print 2D matrix codes, e.g. Datamatrix.

LED matrix

A LED matrix display scanning by rows to make the letter W Dot matrix.gif
A LED matrix display scanning by rows to make the letter W

A LED matrix or LED display is a large, low-resolution form of dot-matrix display, useful both for industrial and commercial information displays as well as for hobbyist human–machine interfaces. It consists of a 2-D diode matrix with their cathodes joined in rows and their anodes joined in columns (or vice versa). By controlling the flow of electricity through each row and column pair it is possible to control each LED individually. By multiplexing, scanning across rows, quickly flashing the LEDs on and off, it is possible to create characters or pictures to display information to the user. [4] By varying the pulse rate per LED, the display can approximate levels of brightness. Multi-colored LEDs or RGB-colored LEDs permit use as a full-color image display. The refresh rate is typically fast enough to prevent the human eye from detecting the flicker.

The primary difference between a common LED matrix and an OLED display is the large, low resolution dots. The OLED monitor functionally works the same, except there are many times more dots, and they are all much smaller, allowing for greater detail in the displayed patterns.

See also

Related Research Articles

Printer (computing) permanently copies digital text or graphics

In computing, a printer is a peripheral device which makes a persistent representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. The different types of printers include, 3D printer, Inkjot printer, laser printer, thermal printer etc.

Pixel a physical point in a raster image

In digital imaging, a pixel, pel, or picture element is a physical point in a raster image, or the smallest addressable element in an all points addressable display device; so it is the smallest controllable element of a picture represented on the screen.

PostScript (PS) is a page description language in the electronic publishing and desktop publishing business. It is a dynamically typed, concatenative programming language and was created at Adobe Systems by John Warnock, Charles Geschke, Doug Brotz, Ed Taft and Bill Paxton from 1982 to 1984.

Raster graphics Dot matrix data structure, representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium

In computer graphics, a raster graphics or bitmap image is a dot matrix data structure that represents a generally rectangular grid of pixels, viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats.

Vector graphics type of 2D digital illustration that uses geometric and styling definitions to represent images

Vector graphics are computer graphics images that are defined in terms of 2D points, which are connected by lines and curves to form polygons and other shapes. Each of these points has a definite position on the x- and y-axis of the work plane and determines the direction of the path; further, each path may have various properties including values for stroke color, shape, curve, thickness, and fill. Vector graphics are commonly found today in the SVG, EPS, PDF or AI graphic file formats and are intrinsically different from the more common raster graphics file formats such as JPEG, PNG, APNG, GIF, and MPEG4.

2D computer graphics graphics that use a two-dimensional representation of geometric data

2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them. The word may stand for the branch of computer science that comprises such techniques or for the models themselves.

Raster image processor

A raster image processor (RIP) is a component used in a printing system which produces a raster image also known as a bitmap. Such a bitmap is used by a later stage of the printing system to produce the printed output. The input may be a page description in a high-level page description language such as PostScript, PDF, or XPS. The input can be or include bitmaps of higher or lower resolution than the output device, which the RIP resizes using an image scaling algorithm.

Laser printing electrostatic digital printing process

Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image. The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated in order to permanently fuse the text, imagery, or both, to the paper. As with digital photocopiers, laser printers employ a xerographic printing process. Laser printing differs from traditional xerography as implemented in analog photocopiers in that in the latter, the image is formed by reflecting light off an existing document onto the exposed drum.

Dot matrix printing class of printers

Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers typically use a print head that moves back and forth or in an up-and-down motion on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like the print mechanism on a typewriter or line printer. However, a dot matrix printer is able to print arbitrary patterns and not just specific characters.

Rasterisation process of describing an image in terms of a pixel or voxel grid (named after the Latin word for rake, as the picture/volumetric elements are usually arranged in lines like those produced by a rake)

Rasterisation is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image. The rasterised image may then be displayed on a computer display, video display or printer, or stored in a bitmap file format. Rasterisation may refer to either the conversion of models into raster files, or the conversion of 2D rendering primitives such as polygons or line segments into a rasterized format.

Daisy wheel printing impact printing technology

Daisy wheel printing is an impact printing technology invented in 1970 by Dr Andrew Gabor at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to three times faster. Daisy wheel printing was used in electronic typewriters, word processors and computers from 1972. The daisy wheel is considered to be so named because of its resemblance to the daisy flower.

Dye-sublimation printer heat transfer printer

A dye-sublimation printer is a computer printer which uses heat to transfer dye onto materials such as a plastic, card, paper, or fabric. The sublimation name was first applied because the dye was considered to make the transition between the solid and gas states without going through a liquid stage. This understanding of the process was later shown to be incorrect, as there is some liquefying of the dye. Since then, the proper name for the process became to be known as dye-diffusion, though this has not eliminated the original name. Many consumer and professional dye-sublimation printers are designed and used for producing photographic prints, ID cards, clothing, and more.

Dots per inch unit of measurement

Dots per inch is a measure of spatial printing, video or image scanner dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch (2.54 cm). Similarly, the more newly introduced dots per centimeter refers to the number of individual dots that can be placed within a line of 1 centimeter (≈ 0.393 in).

Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a character set. Text mode is contrasted to all points addressable (APA) mode or other kinds of computer graphics modes.

Dot matrix printer dot matrix printer that uses impact rather than a nozzle, light, or other means to transfer dots from a dot matrix to the printing surface

A dot matrix printer is an impact printer that prints using a fixed number of pins or wires. In contrast, inkjet and laser printers technically exhibit dot matrix printing, but they are not considered "dot matrix printers".

A computer font is implemented as a digital data file containing a set of graphically related glyphs, characters, or symbols such as dingbats. Although the term font first referred to a set of movable metal type pieces in one style and size, since the 1990s it is generally used to refer to a set of digital shapes in a single style, scalable to different sizes. A font family or typeface refers to the collection of related fonts across styles and sizes.

A letter-quality printer was a form of computer impact printer that was able to printing with the quality typically expected from a business typewriter such as an IBM Selectric.

Printer Command Language, more commonly referred to as PCL, is a page description language (PDL) developed by Hewlett-Packard as a printer protocol and has become a de facto industry standard. Originally developed for early inkjet printers in 1984, PCL has been released in varying levels for thermal, matrix, and page printers. HP-GL/2 and PJL are supported by later versions of PCL.

Semigraphics method used in early text mode video hardware to emulate raster graphics

Text-based semigraphics or pseudographics is a primitive method used in early text mode video hardware to emulate raster graphics without having to implement the logic for such a display mode.

Near letter-quality (NLQ) printing is a process where dot matrix printers produce high-quality text by using multiple passes to produce higher dot density. The tradeoff for the improved print quality is reduced printing speed. Software can also be used to produce this effect. The term was coined in the 1980s to distinguish NLQ printing from true letter-quality printing, as produced by a printer based on traditional typewriter technology such as a daisy wheel, or by a laser printer.

References

  1. Matick, R.; Ling, D. T.; Gupta, S.; Dill, F. (2006) [1984], "All points addressable raster display memory", IBM Journal of Research and Development, 28 (4): 379, doi:10.1147/rd.284.0379 , retrieved 2013-09-28
  2. 1 2 Gonzalez, John Cambell (1982), Zippel, Richard E. (ed.), Implementing a window system for an all points addressable display, Massachusetts Institute of Technology, hdl:1721.1/27922
  3. ERIK SANDBERG-DIMENT (June 4, 1985). "PERSONAL COMPUTERS; LETTER QUALITY, ALMOST".
  4. Claus Kühnel (2001). BASCOM Programming of Microcontrollers with Ease: An Introduction by Program Examples. Universal Publishers. pp. 114–119. ISBN   978-1-58112-671-6.