Editing Cathode-ray tube (section)

====Shadow mask====
{{Main|Shadow mask}}
The shadow mask absorbs or reflects electrons that would otherwise strike the wrong phosphor dots,<ref name="auto91"/> causing color purity issues (discoloration of images); in other words, when set up correctly, the shadow mask helps ensure color purity.<ref name="auto6"/> When the electrons strike the shadow mask, they release their energy as heat and x-rays. If the electrons have too much energy due to an anode voltage that is too high for example, the shadow mask can warp due to the heat, which can also happen during the Lehr baking at ~435&nbsp;°C of the frit seal between the faceplate and the funnel of the CRT.<ref name="auto66"/><ref>{{Cite web|url=https://patents.google.com/patent/US4327307A/en|title=Shadow mask for color cathode ray tube|accessdate=18 December 2022}}</ref>

Shadow masks were replaced in TVs by slot masks in the 1970s, since slot masks let more electrons through, increasing image brightness. Shadow masks may be connected electrically to the anode of the CRT.<ref>{{Cite web|url=https://patents.google.com/patent/US3543072A/en|title=Color cathode ray tube with metallic contactor ribbon bonded on inside wall of tube between the high voltage terminal and the shadow mask frame|accessdate=18 December 2022}}</ref><ref name="auto40"/><ref>{{cite web |url=https://global.sharp/100th/pdf/gravure.pdf |archive-url=https://web.archive.org/web/20210126133217/https://global.sharp/100th/pdf/gravure.pdf |archive-date=2021-01-26 |url-status=live |title= Sharp radios over the years|website=global.sharp |access-date=2020-12-11}}</ref><ref name="auto14">{{Cite web|url=https://stweb.peelschools.org/pcsweb/pc_tut/06crtmon.htm|title=CRT Monitors|website=stweb.peelschools.org|access-date=8 December 2020|archive-date=16 April 2020|archive-url=https://web.archive.org/web/20200416205016/http://stweb.peelschools.org/pcsweb/pc_tut/06crtmon.htm|url-status=dead}}</ref> Trinitron used a single electron gun with three cathodes instead of three complete guns. CRT PC monitors usually use shadow masks, except for Sony's Trinitron, Mitsubishi's Diamondtron and NEC's [[Cromaclear]]; Trinitron and Diamondtron use aperture grilles while Cromaclear uses a slot mask. Some shadow mask CRTs have color phosphors that are smaller in diameter than the electron beams used to light them,<ref name="auto103">{{Cite web|url=https://patents.google.com/patent/US4251610A/en|title=Method of making multicolor CRT display screen with minimal phosphor contamination|accessdate=18 December 2022}}</ref> with the intention being to cover the entire phosphor, increasing image brightness.<ref name="auto55">{{Cite magazine|title=Mac's Service Shop: Zenith's 1973 Color Line<!--http://www.rfcafe.com/references/popular-electronics/macs-service-shop-zenith-1973-color-tv-popular-electronics-march-1973.htm -->|date=March 1973|magazine=Popular Electronics}}</ref> Shadow masks may be pressed into a curved shape.<ref>{{Cite web|url=https://patents.google.com/patent/US4482334A/en|title=Method for making CRT shadow masks|accessdate=18 December 2022}}</ref><ref>{{Cite web|url=https://www.freepatentsonline.com/4859901.html|title=Color CRT shadow mask with wrinkle-free corners|accessdate=18 December 2022}}</ref><ref>{{Cite web|url=https://books.google.com/books?id=jniJTaz6zDMC&q=shadow+mask+crt+tapered&pg=RA1-PA57|title = Official Gazette of the United States Patent and Trademark Office: Patents|year = 1990}}</ref>