화면 보호기

	Before the proliferation of LCD screens, most computer screens depended on cathode ray tubes (CRTs). Images on a CRT monitor are generated using electron beams which are emitted from electron guns at the back of the tube, and manipulated by electromagnetic fields to form images line-by-line on the phosphorescent screen many times per second. In some situations the images displayed on the screen constantly change, but in other cases some areas of the screen, or the screen as a whole, change very little (the taskbar in Microsoft Windows, for example). When the same image is displayed on a CRT screen for long periods of time, the properties of the exposed areas of phosphor coating on the inside of the screen gradually and permanently change, eventually leading to a darkened shadow or "ghost" image on the screen. Televisions, oscilloscopes and other devices that use CRTs are all susceptible to phosphor burn-in, as are plasma displays to some extent. Screensaver programs were originally designed to help avoid these effects by automatically changing the images on the screen when the computer was not in use (thus "saving" the screen). They can be usually set up to launch automatically, waiting a specified amount of time after the last keystroke or the last mouse movement made by a user. The screensaver then blanks the screen, or more commonly produces animation effects, thus avoiding any "fixed" images. The screensaver remains active until a user presses a key or makes a mouse movement. At that moment, the screensaver closes and the former screen contents are restored, allowing the user to work again. For CRTs used in public embedded applications such as ATMs and railway ticketing machines, the risk of burn-in is especially high because a stand-by display is shown whenever the machine is not in use. Older machines designed without burn-in problems taken into consideration often display evidence of screen damage, with images or text such as "Please insert your card" (in the case of ATMs) visible even when the display changes while the machine is in use. Blanking the screen is out of the question as it would make the machine look out of service. Thus, in these applications, burn-in is prevented by moving the contents of the display around every few seconds, or by having a number of different images that are changed regularly. Modern CRTs are much less susceptible to burn-in than older models due to improvements in phosphor coatings, and because modern computer images are generally lower contrast than the stark green- or white-on-black text and graphics of earlier machines. LCD computer monitors, including the display panels used in laptop computers, are not susceptible to burn-in because the image is not directly produced by phosphors (although they can suffer from a less extreme and usually non-permanent form of image persistence). For these reasons, screensavers today are primarily decorative or for entertainment, and usually feature moving images or patterns and sometimes sound effects.

한역 : 요즘 아주 잘나가는 LCD 모니터는 괜찮은데, 아직도 구식 CRT 모니터를 쓰면 무조건 화면보호기를 적용해야 한다는 사실을 깨닫게 하고 있습니다. 만약에 CRT에서 화면보호기를 적용하지 않으면 CRT에서 잔상이 남는다고 합니다.

화면 보호기는 모니터에 잔상이 남는 것을 막기 위해 만들어진 소프트웨어이다. 많은 운영 체제에는 화면 보호기 기능이 있으며 화면 보호기가 구동될 때 CRT 모니터와 PDP 모니터의 경우에는 전력을 절약해 줄 수 있다.

효과

하지만 원작자의 말에 의하면 화면보호기는 절전에 아무런 도움이 안 된다고 한다. 단지 확실한 방법은 모니터를 끄는 것이다. 게다가 화면 보호기는 작업 내용을 보호하고 건드림을 방지하는 것이라는 주장도 있다. CRT 모니터의 경우 화면에 같은 게 너무 오래 떠 있으면 번인 현상이 생긴다고 한다. 대개 화면 보호기는 위의 장황한 영어 문장처럼 별 쓸데없는 (그리고 움직이는) 화면을 수시로 표시해준다.

그러나... 이 페이지의 앞에 있는 공포스러운 영어를 보는 순간 번인 현상을 막을 수 있을 것이다. 한 페이지에 고정하기 싫고 분명히 alt-x 혹은 임의 문서로 링크를 눌렀을 지도 모른다.

한편 컴퓨터 중독자들에게는 화면 보호기가 실행되어 있는 모니터를 보았을 때 그 화면 보호기를 꺼버리고 싶은 충동을 자제할 수 없는 일종의 정신병이 있기 때문에, 결국 대부분의 환경에서 화면 보호기는 제 역할을 하지 못한다.

주석