Vector monitor

Last updated
A 24-hour clock displayed on an oscilloscope configured as a vector monitor in X-Y mode with dual R2R DACs to generate the analog voltages Oscilloscope clock.jpg
A 24-hour clock displayed on an oscilloscope configured as a vector monitor in X-Y mode with dual R2R DACs to generate the analog voltages

A vector monitor, vector display, or calligraphic display is a display device used for computer graphics up through the 1970s. It is a type of CRT, similar to that of an early oscilloscope. In a vector display, the image is composed of drawn lines rather than a grid of glowing pixels as in raster graphics. The electron beam follows an arbitrary path, tracing the connected sloped lines rather than following the same horizontal raster path for all images. The beam skips over dark areas of the image without visiting their points.

Contents

Some refresh vector displays use a normal phosphor that fades rapidly and needs constant refreshing 30-40 times per second to show a stable image. These displays, such as the Imlac PDS-1, require some local refresh memory to hold the vector endpoint data. Other storage tube displays, such as the popular Tektronix 4010, use a special phosphor that continues glowing for many minutes. Storage displays do not require any local memory. In the 1970s, both types of vector displays were much more affordable than bitmap raster graphics displays when megapixel computer memory was still very expensive. Today, raster displays have replaced nearly all uses of vector displays.

Vector displays do not suffer from the display artifacts of aliasing and pixelation—especially black and white displays; color displays keep some artifacts due to their discrete nature—but they are limited to displaying only a shape's outline (although advanced vector systems can provide a limited amount of shading). Text is crudely drawn from short strokes. Refresh vector displays are limited in how many lines or how much text can be shown without refresh flicker. Irregular beam motion is slower than steady beam motion of raster displays. Beam deflections are typically driven by magnetic coils, and those coils resist rapid changes to their current.

History

The vector display was first invented by Jonathan Zenneck via use of a Braun cathode-ray tube. His solution was able to produce fundamental waveforms using two deflection cowls a high-powered cathode inside of the tube to create a continuously swept image. [1] This device was utilized by early radio engineers, but was not practical until John Bertrand Johnson implemented the hot cathode to drastically reduce the voltage requirements for the device. The Cathode Ray Oscillograph was subsequently commercialized and became the basis for the modern oscilloscope. [2]

Oscilloscopes were used by electrical engineers to map out physical forces, as well as by recording engineers to understand the nature of human voices. [3] The displays also became a frequent add-on to advanced electronic analog computers to visualize complex forces. The first RADAR systems utilized vector graphic oscilloscopes to map aircraft positions.

Vector graphics in computers first emerged with the Whirlwind system built by the Massachusetts Institute of Technology's Lincoln Laboratory. Utilizing oscilloscope tubes, the Whirlwind displays could produce complex readings of airborne trajectory, as well as played host to the first graphical demo, Bouncing Ball (1951). In 1956, the first light pen was implemented on the Whirlwind system. These technologies then became the basis for the advanced US SAGE air defense system which was fully active in 1958. [4]

In 1963, Ivan Sutherland at MIT first used a vector graphic display for Sketchpad, his pioneering CAD program. In 1968, he and his team again used a vector monitor to display wireframe images of 3D models. This time the display was head mounted. The obviously heavy system was held up by a support arm structure called The Sword of Damocles. The system is widely considered to be the first computer-based virtual reality. Ivan Sutherland later co-founded the company Evans & Sutherland, which made high-end vector displays and flight simulators.

In 1970, at the UK Farnborough Airshow, Sperry Gyroscope (Bracknell, England) exhibited the first ever vector graphic video display from a UK company. It featured an analogue monochrome display with special electronics, designed by Sperry's John Atkins, that allowed it to draw vectors on screen between two pairs of coordinates. At Farnborough the display was used to demonstrate the capabilities of the new Sperry 1412 military computer - it was shown running software that drew, in real time, a wire-frame rotating cube that could be speed-controlled in any of its three dimensions. That demonstration created significant interest in the Sperry 1412 computer, which then went on to be at the heart of a number of major projects for the French Navy and the Royal Navy during the period 1972 to 1992.

Examples

Notable among vector displays are Tektronix large-screen computer terminals that use direct-view storage CRTs. (The CRT has at least one flood gun, and a special type of display screen, more complicated in principle than a simple phosphor.) But that permanent image cannot be easily changed. Like an Etch-a-Sketch, any deletion or movement requires erasing the entire screen with a bright green flash, and then slowly redrawing the entire image. Animation with this type of monitor is not practical.

Vector displays were used for head-up displays in fighter aircraft because of the brighter displays that can be achieved by moving the electron beam more slowly across the phosphors. Brightness was critical because the display needed to be clearly visible to the pilot in direct sunlight.

A free software Asteroids-like video game played on an oscillograph configured in X-Y mode Space Rocks (game).jpg
A free software Asteroids-like video game played on an oscillograph configured in X-Y mode

Vector monitors were also used by some late-1970s to mid-1980s arcade games such as Armor Attack , Asteroids , Omega Race , Tempest , and Star Wars , [5] and in the Vectrex home videogame console.

Hewlett-Packard made a series of large-screen X-Y (vector) displays, the first of which was the 20 MHz 8x10-inch model 1300. The CRT had an internal, specially contoured, very fine mesh operating at low potential, which was placed after the deflection plates at the gun exit. The 17KV electrostatic field between this mesh and the separate, conductive coating charged to final accelerating potential inside the CRT funnel, accelerated the electron beam axially as well as radially, expanding the possible image size to cover the 8x10" screen of the 17.75-inch long CRT. Without the mesh, the 8x10-inch CRT would have had to be almost three times as long. [6] Expansion mesh technology was developed in the early 1960s [7] by the need to drive deflection plates at high frequencies in compact high-brightness CRTs operating at high acceleration voltages, to take advantage of the then-new transistor technology which was limited to only low voltages. The much bulkier and less efficient vacuum-tube electrostatic deflection amplifiers were able to operate at hundreds of volts.

The Digistar planetarium projection system, made by Evans & Sutherland, was originally a vector display that could render both stars and wire-frame graphics. Later versions use high resolution raster projection, but the vector-based Digistar and Digistar II were installed in many planetariums, and a few may still be in operation. [8] [9] [10] A Digistar prototype was used for rendering 3D star fields for the film Star Trek II: The Wrath of Khan. Another E&S vector display, the Picture System II, was possibly also used for the film. [11]

Color displays

Some vector monitors are capable of displaying multiple colors, using either a typical shadow mask RGB CRT or two phosphor layers (so-called "penetration color").

Atari used the term color quadrascan to describe the shadow-mask version used in their video arcade games. [12] [13]

In the penetration tubes, by controlling the strength of the electron beam, electrons can be made to reach (and illuminate) either or both phosphor layers, typically producing a choice of green, orange, or red.

Tektronix made color oscilloscopes for a few years using penetration CRTs, but demand for these was low.[ citation needed ]

Some monochrome vector displays were able to display color using peripherals such as the Vectrex 3-D Imager.

See also

Related Research Articles

<span class="mw-page-title-main">Cathode-ray tube</span> Vacuum tube often used to display images

A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a frame of video on an analog television set (TV), digital raster graphics on a computer monitor, or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons.

<span class="mw-page-title-main">Vectrex</span> Vector display-based home video game console

The Vectrex is a vector display-based home video game console - the only one ever designed and released for the home market, that was developed by Smith Engineering and manufactured and sold by General Consumer Electronics. It was first released for the North America market in October 1982 and then Europe and Japan in 1983. Originally produced by General Consumer Electronics, it was later licensed to Milton Bradley after they acquired the company. Bandai released the system in Japan.

<span class="mw-page-title-main">Framebuffer</span> Portion of random-access memory containing a bitmap that drives a video display

A framebuffer is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Modern video cards contain framebuffer circuitry in their cores. This circuitry converts an in-memory bitmap into a video signal that can be displayed on a computer monitor.

The refresh rate, also known as vertical refresh rate or vertical scan rate in reference to terminology originating with the cathode-ray tubes (CRTs), is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate, which describes how many images are stored or generated every second by the device driving the display. On CRT displays, higher refresh rates produce less flickering, thereby reducing eye strain. In other technologies such as liquid-crystal displays, the refresh rate affects only how often the image can potentially be updated.

<span class="mw-page-title-main">Tektronix 4010</span> Text and graphics computer terminals

The Tektronix 4010 series was a family of text-and-graphics computer terminals based on storage-tube technology created by Tektronix. Several members of the family were introduced during the 1970s, the best known being the 11-inch 4010 and 19-inch 4014, along with the less popular 25-inch 4016. They were widely used in the computer-aided design market in the 1970s and early 1980s.

<span class="mw-page-title-main">Storage tube</span> CRTs designed for use as computer memory

Storage tubes are a class of cathode-ray tubes (CRTs) that are designed to hold an image for a long period of time, typically as long as power is supplied to the tube.

An output device is any piece of computer hardware that converts information or data into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be text, graphics, tactile, audio, or video. Examples include monitors, printers, speakers, headphones, projectors, GPS devices, optical mark readers, and braille readers.

<span class="mw-page-title-main">Direct-view bistable storage tube</span>

Direct-view bistable storage tube (DVBST) was an acronym used by Tektronix to describe their line of storage tubes. These were cathode ray tubes (CRT) that stored information written to them using an analog technique inherent in the CRT and based upon the secondary emission of electrons from the phosphor screen itself. The resulting image was visible in the continuously glowing patterns on the face of the CRT.

<span class="mw-page-title-main">Screen burn-in</span> Disfigurement of an electronic display

Screen burn-in, image burn-in, ghost image, or shadow image, is a permanent discoloration of areas on an electronic visual display such as a cathode-ray tube (CRT) in an older computer monitor or television set. It is caused by cumulative non-uniform use of the screen.

Cromaclear is a trademark for CRT technology used by NEC during the mid to late-90s. This adopted the slotted shadow mask and in-line electron gun pioneered by the 1966 GE Porta-Color and used by most then-current television tubes to computer monitor use. It was claimed that Cromaclear could offer the image clarity and sharpness of the Trinitron and Diamondtron aperture grille CRTs without the disadvantages e.g. expense and the horizontal damping wires.

Calligraphic projection is a system for displaying or projecting an image composed of a beam of light or electrons directly tracing the image, as opposed to sweeping in raster order over the entire display surface, as in a standard pixel-based display. Calligraphic projection is presently often used for laser lighting displays, whereby one or more laser beams draws an image on a screen by reflecting the laser beam from one or more mirrors attached to a deflecting mechanism.

<span class="mw-page-title-main">IMLAC</span> Graphical display system

IMLAC Corporation was an American electronics company in Needham, Massachusetts, that manufactured graphical display systems, mainly the PDS-1 and PDS-4, in the 1970s.

<span class="mw-page-title-main">Raster scan</span> Rectangular pattern of image capture and reconstruction

A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image systems. The word raster comes from the Latin word rastrum, which is derived from radere ; see also rastrum, an instrument for drawing musical staff lines. The pattern left by the lines of a rake, when drawn straight, resembles the parallel lines of a raster: this line-by-line scanning is what creates a raster. It is a systematic process of covering the area progressively, one line at a time. Although often a great deal faster, it is similar in the most general sense to how one's gaze travels when one reads lines of text.

Digistar is the first computer graphics-based planetarium projection and content system. It was designed by Evans & Sutherland and released in 1983. The technology originally focused on accurate and high quality display of stars, including for the first time showing stars from points of view other than Earth's surface, travelling through the stars, and accurately showing celestial bodies from different times in the past and future. Beginning with the Digistar 3 the system now projects full-dome video.

Electrically operated display devices have developed from electromechanical systems for display of text, up to all-electronic devices capable of full-motion 3D color graphic displays. Electromagnetic devices, using a solenoid coil to control a visible flag or flap, were the earliest type, and were used for text displays such as stock market prices and arrival/departure display times. The cathode ray tube was the workhorse of text and video display technology for several decades until being displaced by plasma, liquid crystal (LCD), and solid-state devices such as thin-film transistors (TFTs), LEDs and OLEDs. With the advent of metal–oxide–semiconductor field-effect transistors (MOSFETs), integrated circuit (IC) chips, microprocessors, and microelectronic devices, many more individual picture elements ("pixels") could be incorporated into one display device, allowing graphic displays and video.

A scotophor is a material showing reversible darkening and bleaching when subjected to certain types of radiation. The name means dark bearer, in contrast to phosphor, which means light bearer. Scotophors show tenebrescence and darken when subjected to an intense radiation such as sunlight. Minerals showing such behavior include hackmanite sodalite, spodumene and tugtupite. Some pure alkali halides also show such behavior.

This is a subdivision of the Oscilloscope article, discussing the various types and models of oscilloscopes in greater detail.

<span class="mw-page-title-main">History of the oscilloscope</span>


The history of the oscilloscope was fundamental to science because an oscilloscope is a device for viewing waveform oscillations, as of electrical voltage or current, in order to measure frequency and other wave characteristics. This was important in developing electromagnetic theory. The first recordings of waveforms were with a galvanometer coupled to a mechanical drawing system dating from the second decade of the 19th century. The modern day digital oscilloscope is a consequence of multiple generations of development of the oscillograph, cathode-ray tubes, analog oscilloscopes, and digital electronics.

A time base generator is a special type of function generator, an electronic circuit that generates a varying voltage to produce a particular waveform. Time base generators produce very high frequency sawtooth waves specifically designed to deflect the beam of a cathode ray tube (CRT) smoothly across the face of the tube and then return it to its starting position.

<span class="mw-page-title-main">Deflection yoke</span> Part of a cathode ray tube which moves the electron beam around

A deflection yoke is a kind of magnetic lens, used in cathode ray tubes to scan the electron beam both vertically and horizontally over the whole screen.

References

  1. ↑ Marton, L. (1980). "Ferdinand Braun: Forgotten Forefather". Advances in electronics and electron physics. Vol. 50. Academic Press. p. 252. ISBN   978-0-12-014650-5 . Retrieved 2011-01-19.
  2. ↑ "Western Electric Cathode Ray Oscillograph Tube". Journal of the Optical Society of America and Review of Scientific Instruments. 9 (6): XXIX. December 1924.
  3. ↑ Burt, Dr. Robert E. (1928-06-03). "How Science Photographs Music". The San Francisco Examiner. pp. 6K.
  4. ↑ Holzer, Derek (April 2019). Vector Synthesis: a Media-Archaeological Investigation into Sound-Modulated Light (PDF) (Thesis). Aalto University. urn:urn:NBN:fi:aalto-201905193156 . Retrieved July 31, 2020.
  5. ↑ Van Burnham (2001). Supercade: A Visual History of the Videogame Age, 1971-1984. MIT Press. ISBN   0-262-52420-1.
  6. ↑ Russell, Milton E. (December 1967). "Factors in Designing a Large-Screen, Wideband CRT" (PDF). Hewlett-Packard Journal. 19 - Number 4: 10–11.
  7. ↑ Peter A. Keller (December 2007) Tektronix CRT History Part 6 - CRTs for Solid-State Instruments
  8. ↑ "Nagoya City Science Museum - Exhibition Guide - Digistar II". www.ncsm.city.nagoya.jp. Nagoya City Science Museum. Retrieved 14 September 2024.
  9. ↑ "Evans_and_Sutherland Digistar-II". planetariums-database.org. Worldwide Planetariums Database. Retrieved 14 September 2024.
  10. ↑ "Listing of Planetariums using a Evans_and_Sutherland Digistar-II". planetariums-database.org. Worldwide Planetariums Database. Retrieved 14 September 2024.
  11. ↑ Smith, Alvy Ray (October 1982). "Special Effects for Star Trek II: The Genesis Demo" (PDF). American Cinematographer: 1038. Retrieved 14 September 2024.
  12. ↑ "Atari's New Color Quadrascan (X-Y) Monitor" (PDF) (Press release). Atari Incorporated. 1981-09-24. Retrieved 2012-05-06.
  13. ↑ "Wells-Gardner 6100 Vector Monitor FAQ and Guide" (PDF). 2002-03-01. Retrieved 2012-05-06.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.