Screen of day before

A screen of day before is a Computer program of which the original goal was to preserve the quality of image of the screens of computers, by stopping posting the screen (black screen), or by changing the colors posted on each pixel (reasons and animations). The word English to indicate them is screensaver , which literally means “saver of screen”.

Utility

Currently (July 2006) the majority of the screens of computer which are manufactured rest on recent technologies such as posting with Liquid crystals. These technologies tend to replace gradually the technology of the Cathode tube which were until now the principal technology used for the monitors and Télévision S. These screens that one calls screens with cathode tube (or screens CRT in reference at the end English Cathod Ray Tube ) use rays of electrons which are emitted by the electron gun placed at the rear of the cathode tube and using electromagnetic fields deviates them to produce images line by line and this of many times a second. In certain situations, the images posted with the screen change constantly, but in other cases certain zones of the screen or the whole screen remain identical for one long period (as for examples the Barre of the tasks in Windows). When the same image is posted with the screen during an important time, the properties of the coverage areas of phosphorus inside the screen which are exposed change gradually and regularly and with final phenomenon of shade or “phantom image” can appear on the screen. Televisions, the oscilloscopes and other apparatuses functioning with a cathode tube are all likely to undergo this phenomenon of internal Combustion of phosphorus, like the plasma display screens to a certain extent.

The purpose of the screens of day before were thus in the beginning to protect the screens from this phenomenon by automatically changing the images posted with the screen at the end of a certain time from inactivity (from where the English name screensaver which means “saver of screen”). Usually, they can be regulated so that they start automatically after a certain time of inactivity, i.e. no event is produced during this period what results in the fact that no key of the keyboard was inserted and that the mouse was not moved. Generally the work of the screen of day before then consists in erasing the screen (there remains only one black uniform color then) or posting graphics animated, thus avoiding with the screen permanently posting the same image and worsening gradually. As long as no key of the keyboard is inserted and that the mouse is not moved, the screen of day before remains active. If the preceding event occurs, then the screen of day before stops and the screen again posts the image which it posted before the screen of day before does not start, thus making it possible the user to resume his work.

With regard to screens CRT used in the public terminals as the automatic counter of bank or them terminals for the reservation in the stations of train (as the terminals the SNCF), the risk of deterioration by internal combustion is particularly high since the screen posts the same image as soon as the apparatus is not used. This problem was rather obvious with the old machines for which the phenomenon of combustion interns had not been taken into account as the automated tellers on which a message of the kind “Insert your chart” remained visible even when the apparatus was used. With these apparatuses, out-of-question of returning the black screen because that could let think that it is out-service. And thus generally the problem is circumvented while making move the contents of the screen regularly or while making alternate various images with the screen.

Modern screens CRT are less likely to undergo the internal phenomenon of combustion compared with the old models bus of the improvements were brought to the coating phosphorus screens and the images posted with the screen less luminous and are generally nowadays contrasted that the images of the first computers which posted luminous green or white on a black bottom. Screens LCD of the computers (including the screens of the laptops) are not likely to undergo effect of combustion internal because the images are not produced using phosphorus (although they can suffer from a way less important of a phenomenon of Persistance of image and this in a temporary way). For these reasons, the screens of day before currently are used for decorative and ludic reasons. Usually, they post animated images or reasons and are accompanied sometimes by sound effects.

Reflection

The screens of computers consume the same quantity of energy when a screen of day before is active that when there is not. This quantity can vary between some Watt S for small screens LCD and several hundreds for more the big screens plasma. The majority of the recent computers can be configured to rock the screens in a mode of low fuel consumption while returning the black screen. The majority of the recent Operating systems generally propose options of management of the food and in particular a mode of energy saving for the screen.

Moreover, to use a screen of day before with a flat panel display or a screen LCD instead of extinguishing it can in makes reduce its lifespan, because the fluorescent lamp of the Rétroéclairage remains lit and thus ages more quickly than if the screen were completely extinct. As the fluorescent tubes age they become gradually increasingly weak, and they can be very expensive or difficult to replace. A traditional screen LCD loses approximately 50% of its luminosity during one lifespan of normal product, this luminosity is lost gradually continuously. (Generally, the tube is an integral part of liquid crystals and the whole assembly must be replaced).

Thus currently in the majority of the cases, the English name screensaver to indicate a screen of day before is not really quite selected because best the way of preserving a screen (and of saving electricity) would be quite simply that the computer extinguishes the screen.

Entertainment

After Dark was one of the first screens of day before for the platform Macintosh and which revealed with the screen eccentric objects like flying Grill-pain S. Several screens of day before continued to probably preserve this whimsical side in answer to the serious one of the work places in which they could be observed and made popular the inactive screens with animals, fish, plays, and entertaining Mathématiques like the Fractales.

This side diverting and ludic screens of day before is made profitable with an aim of promotion, to produce in particular a buzz for the products whose exit is planned like the Film S or the video games.

Artistic creation

The first starting constraint of the screens of day before is to present on the monitor of the computer of the forms moving. The second constraint was that these animations are pleasant to look at. It very natural that the savers of screens approach the culture of the demonstration or that of artistic creation on computer of the beginning of the Années 1970 (John Whitney for example), was strongly influenced by COp art/Kinetic art. Thereafter, of the artists screens of day before produced, like Francis Alÿs ( The Thief , produced by Walker art center).

Safety

Microsoft Windows

History

The first screen of day before was written for the IBM PC by John Socha, more known to have created the Gestionnaire of files Norton Commander. It is also at the origin of the term screensaver . This first screen of day before (named scrnsave since the file names at the time could not exceed 8 letters) was published in December 1983 in the magazine Softalk. It was satisfied then at the time quite simply returning the black screen at the end of three minutes (amount of time which could be modified only by recompilant the program!).

Subjacent architecture

The writing of screens of day before often calls upon graphic libraries such as OpenGL, GDI (Windows), DirectX (Windows), Quartz (Mac)…

Internal bonds

XScreenSaver

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