Dot matrix

Last updated October 25, 2024

A dot matrix is a 2-dimensional patterned array, used to represent characters, symbols and images. Most types of modern technology use dot matrices for display of information, including mobile phones, televisions, and printers. The system is also used in textiles with sewing, knitting and weaving.

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 leave the interiors of closed vector shapes unfilled, or perform slow, time-consuming and often non-uniform shape-filling, 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.

Use 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.

Use 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

laser printing
inkjet printing
dot matrix printers

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

An 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.

Related Research Articles

In computing, a printer is a peripheral machine which makes a durable 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. Different types of printers include 3D printers, inkjet printers, laser printers, and thermal printers.

A plotter is a machine that produces vector graphics drawings. Plotters draw lines on paper using a pen, or in some applications, use a knife to cut a material like vinyl or leather. In the latter case, they are sometimes known as a cutting plotter.

PostScript (PS) is a page description language and dynamically typed, stack-based programming language. It is most commonly used in the electronic publishing and desktop publishing realm, but as a Turing complete programming language, it can be used for many other purposes as well. PostScript was created at Adobe Systems by John Warnock, Charles Geschke, Doug Brotz, Ed Taft and Bill Paxton from 1982 to 1984. The most recent version, PostScript 3, was released in 1997.

<span class="mw-page-title-main">Raster graphics</span> Image display as a 2D grid of pixels

In computer graphics and digital photography, a raster graphic represents a two-dimensional picture as a rectangular matrix or grid of pixels, viewable via a computer display, paper, or other display medium. A raster image is technically characterized by the width and height of the image in pixels and by the number of bits per pixel. Raster images are stored in image files with varying dissemination, production, generation, and acquisition formats.

Vector graphics are a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display and printing hardware, vector data models and file formats, as well as the software based on these data models. Vector graphics are an alternative to raster or bitmap graphics, with each having advantages and disadvantages in specific situations.

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 also be or include bitmaps of higher or lower resolution than the output device, which the RIP resizes using an image scaling algorithm.

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 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, 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 are a type of impact printer that prints using a fixed number of pins or wires and 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. They were also known as serial dot matrix printers. Unlike typewriters or line printers that use a similar print mechanism, a dot matrix printer can print arbitrary patterns and not just specific characters.

In computer graphics, rasterisation or rasterization is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image. The rasterized image may then be displayed on a computer display, video display or printer, or stored in a bitmap file format. Rasterization may refer to the technique of drawing 3D models, or to the conversion of 2D rendering primitives, such as polygons and line segments, into a rasterized format.

Daisy wheel printing is an impact printing technology invented in 1970 by 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 so named because of its resemblance to the daisy flower.

<span class="mw-page-title-main">Dots per inch</span> Measure of dot density

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, dots per centimetre refers to the number of individual dots that can be placed within a line of 1 centimetre (0.394 in).

<span class="mw-page-title-main">Thermal-transfer printing</span> Digital printing method

Thermal-transfer printing is a digital printing method in which material is applied to paper by melting a coating of ribbon so that it stays glued to the material on which the print is applied. It contrasts with direct thermal printing, where no ribbon is present in the process.

Thermal printing is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated elements. The coating turns black in the areas where it is heated, producing an image.

A computer font is implemented as a digital data file containing a set of graphically related glyphs. A computer font is designed and created using a font editor. A computer font specifically designed for the computer screen, and not for printing, is a screen font.

A letter-quality printer was a form of computer impact printer that was able to print 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.

UniDrv is a GDI-based Microsoft Windows universal printer driver and architecture for non-PostScript printers. It is used to simplify driver development of non-PostScript printers for printer manufacturers. Unidrv allows the creation of a printer-specific minidriver in the form of a GPD file, similar to a PPD file, which is much simpler than kernel mode driver development. Unidrv was introduced in Windows 2000 and replaced the Raster Device Driver (RASDD) interface used in Windows NT 4.0 and earlier versions.

ESC/P, short for Epson Standard Code for Printers and sometimes styled Escape/P, is a printer control language developed by Epson to control computer printers. It was mainly used in dot matrix printers and some inkjet printers, and is still widely used in many receipt thermal printers. During the era of dot matrix printers, it was also used by other manufacturers, sometimes in modified form. At the time, it was a popular mechanism to add formatting to printed text, and was widely supported in software.

Text-based semigraphics, pseudographics, or character graphics 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

↑ 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
1 2 Gonzalez, John Cambell (1982), Zippel, Richard E. (ed.), Implementing a window system for an all points addressable display (Thesis), Massachusetts Institute of Technology, hdl:1721.1/27922
↑ ERIK SANDBERG-DIMENT (June 4, 1985). "PERSONAL COMPUTERS; LETTER QUALITY, ALMOST". The New York Times.
↑ 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.

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[ibm-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

[mit-2] 1 2 Gonzalez, John Cambell (1982), Zippel, Richard E. (ed.), Implementing a window system for an all points addressable display (Thesis), Massachusetts Institute of Technology, hdl:1721.1/27922

[3] ERIK SANDBERG-DIMENT (June 4, 1985). "PERSONAL COMPUTERS; LETTER QUALITY, ALMOST". The New York Times.

[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.

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