Principle of CCD camera: Difference between revisions
Feedback

From WikiLectures

Visual
No edit summary
No edit summary
 
Line 1: Line 1:


'''CCD čip''' (''Charge-coupled device'') je moderním detektorem obrazu široce používaným v digitálních fotoaparátech, videokamerách i webkamerách. Vlastní princip, je poměrně jednoduchý, krok za krokem je naznačen na následujících obrázcích.
'''A CCD chip''' ( ''Charge-coupled device'' ) is a modern image detector widely used in digital cameras, video cameras and web cameras. The actual principle is quite simple, step by step is indicated in the following pictures.


Základem je destička z čistého křemíku, tedy vlastně intrinzického polovodiče. Na dolní straně je polovodič uzemněn, na straně druhé je kryt vrstvičkou oxidu křemičitého, který se chová jako izolant. Na této vrstvě jsou napařeny plošné elektrody.
The basis is a plate made of pure silicon, i.e. actually an intrinsic semiconductor. On the lower side, the semiconductor is grounded, on the other side it is covered with a layer of silicon dioxide, which acts as an insulator. Surface electrodes are vaporized on this layer.
[[File:CCD in front side illumination..png|center|thumb|553x553px]]




[[Soubor:CCDexpo.png]]
In pure silicon, no free charge carriers are theoretically present. The positive pole of the source is connected to the electrode with number 1, the negative pole is connected to the ground. So the silicon is in an electric field. If a photon hits the silicon, some valence electron can be knocked out of the bond to the silicon atom, and thus an electron-hole pair is formed. Due to the existing electric field, these two charge carriers are separated from each other and each travel to a different side of the silicon wafer. The number of charge carriers released in this way is proportional to the intensity of the incident radiation.
[[File:CCDshift1.png|center|thumb|553x553px]]


V čistém křemíku nejsou teoreticky přítomny žádné volné nosiče náboje. Na elektrodu s číslem 1 je připojen kladný pól zdroje, na uzemnění záporný. Křemík je tedy v elektrickém poli. Pokud do křemíku dopadne foton, může vyrazit některý valenční elektron z vazby na atom křemíku, a tak vznikne pár elektron-díra. Vzhledem k existujícímu elektrickému poli jsou od sebe tyto dva nosiče náboje odděleny a putují každý na jinou stranu křemíkové destičky. Počet takto uvolněných nosičů náboje je úměrný intenzitě dopadajícího záření.


In the next step, the positive charge is disconnected from electrode number 1 and attached to electrode number 2. The charge that was accumulated under electrode number 1 moves under electrode 2, i.e. to the right here in the picture.
[[File:CCDshift2.png|center|thumb|553x553px]]


[[Soubor:CCDshift1.png]]
Quite analogously, the positive charge switches from electrode 2 to electrode 3.
[[File:CCDshift3.png|center|thumb|553x553px]]


V dalším kroku se kladný náboj odpojí od elektrody číslo 1 a připojí se k elektrodě číslo 2. Náboj, který byl nakupen pod elektrodou číslo 1, se posune pod elektrodu 2, tedy zde na obrázku doprava.
And finally it switches from electrode 3 to electrode 1. However, the charge has already moved one whole "cell" to the right.


By repeating, the charge reaches the edge of the silicon wafer and can exit into the attached conductor. The captured current pulse corresponds to the brightness that was applied to the evaluated pixel. Since the switching of electrodes 1−3 is controlled, we have information about where the respective pixel is located at the same time as the brightness.


[[Soubor:CCDshift2.png]]
== Links ==
 
=== Related articles ===
Zcela analogicky se kladný náboj přepne z elektrody 2 na elektrodu 3.
* [[Digital image]]
 
* [https://en.wikipedia.org/wiki/Charge-coupled_device CCD chip on English Wikipedia]
 
* [https://cs.wikipedia.org/wiki/Charge-coupled_device CCD chip on Czech Wikipedia]
[[Soubor:CCDshift3.png]]
 
A nakonec se přepne z elektrody 3 na elektrodu 1. Náboj se však již posunul o jednu celou "buňku" doprava.
 
Opakováním se náboj dostane až na okraj křemíkové destičky a může vystoupit do přiloženého vodiče. Zachycený proudový impuls odpovídá jasu, který působil na hodnocený pixel. Protože je přepínání elektrod 1−3 řízené, máme současně s jasem i informaci o tom, kde se příslušný pixel nachází.
 
== Odkazy ==
=== Související články ===
* [[Digitální obraz]]
* [[w:en:Charge-coupled device|CCD čip na anglické Wikipedii]]
* [[w:cs:Charge-coupled device|CCD čip na české Wikipedii]]


=== External Links ===
=== External Links ===
* J.Březina: [http://www.grafika.cz/art/hw/clanek356807612.html CCD snímače I] na serveru Grafika ON-LINE
* J.Březina: [http://www.grafika.cz/art/hw/clanek356807612.html CCD snímače I] on the Grafika ON-LINE server
* J.Březina: [http://www.grafika.cz/art/hw/clanek472244131.html CCD snímače II]na serveru Grafika ON-LINE
* J.Březina: [http://www.grafika.cz/art/hw/clanek472244131.html CCD snímače II] on the Grafika ON-LINE server
* J.Březina: [http://www.grafika.cz/art/hw/clanek1508315895.html CCD snímače III]na serveru Grafika ON-LINE
* J.Březina: [http://www.grafika.cz/art/hw/clanek1508315895.html CCD snímače III] on the Grafika ON-LINE server
* J.Březina: [http://www.grafika.cz/art/hw/clanek216968175.html CCD snímače IV]na serveru Grafika ON-LINE
* J.Březina: [http://www.grafika.cz/art/hw/clanek216968175.html CCD snímače IV] on the Grafika ON-LINE server

Latest revision as of 22:09, 21 December 2022

A CCD chip ( Charge-coupled device ) is a modern image detector widely used in digital cameras, video cameras and web cameras. The actual principle is quite simple, step by step is indicated in the following pictures.

The basis is a plate made of pure silicon, i.e. actually an intrinsic semiconductor. On the lower side, the semiconductor is grounded, on the other side it is covered with a layer of silicon dioxide, which acts as an insulator. Surface electrodes are vaporized on this layer.

CCD in front side illumination..png


In pure silicon, no free charge carriers are theoretically present. The positive pole of the source is connected to the electrode with number 1, the negative pole is connected to the ground. So the silicon is in an electric field. If a photon hits the silicon, some valence electron can be knocked out of the bond to the silicon atom, and thus an electron-hole pair is formed. Due to the existing electric field, these two charge carriers are separated from each other and each travel to a different side of the silicon wafer. The number of charge carriers released in this way is proportional to the intensity of the incident radiation.

CCDshift1.png


In the next step, the positive charge is disconnected from electrode number 1 and attached to electrode number 2. The charge that was accumulated under electrode number 1 moves under electrode 2, i.e. to the right here in the picture.

CCDshift2.png

Quite analogously, the positive charge switches from electrode 2 to electrode 3.

CCDshift3.png

And finally it switches from electrode 3 to electrode 1. However, the charge has already moved one whole "cell" to the right.

By repeating, the charge reaches the edge of the silicon wafer and can exit into the attached conductor. The captured current pulse corresponds to the brightness that was applied to the evaluated pixel. Since the switching of electrodes 1−3 is controlled, we have information about where the respective pixel is located at the same time as the brightness.

Links[edit | edit source]

Related articles[edit | edit source]

External Links[edit | edit source]

Retrieved from "https://www.wikilectures.eu/index.php?title=Principle_of_CCD_camera&oldid=63297"