Image sensor including a photoelectric conversion film
This image sensor comprises a plurality of pixel electrodes, a photoelectric conversion film arranged on the plurality of pixel electrodes, a dummy electrode formed on an end of the photoelectric conversion film for ejecting charges generated in the vicinity of the end of the photoelectric conversion film and a first transistor for controlling ejection of charges flowing into the dummy electrode.
1. An image sensor comprising:
a plurality of pixel electrodes formed on a pixel region;
a photoelectric conversion film arranged on said plurality of pixel electrodes;
a dummy electrode formed in the vicinity of an end of said photoelectric conversion film for ejecting charges generated in the vicinity of said end of said photoelectric conversion film, formed in a dummy electrode region that is different from the pixel region; and
a first transistor for controlling ejection of charges flowing into said dummy electrode.
2. The image sensor according to claim 1 , wherein
said first transistor is arranged under a region provided with said dummy electrode.
3. The image sensor according to claim 1 , ejecting charges flowing into said dummy electrode by controlling said first transistor into an ON-state before an operation of reading charges from said pixel electrodes.
4. The image sensor according to claim 3 , ejecting charges flowing into said dummy electrode by controlling said first transistor into an ON-state in an imaging period before said operation of reading charges.
5. The image sensor according to claim 1 , wherein
said dummy electrode is electrically connected to a first source/drain region of said first transistor while a positive potential is applied to a second source/drain region of said first transistor.
6. The image sensor according to claim 5 , further comprising an interconnection layer for supplying said positive potential to said second source/drain region of said first transistor, wherein
said interconnection layer is so provided as to extend toward said end of said photoelectric conversion film with respect to said dummy electrode.
7. The image sensor according to claim 1 , wherein
said plurality of pixel electrodes are arranged in the form of a matrix, and
said dummy electrode is so formed as to enclose said pixel electrodes arranged in the form of a matrix.
8. The image sensor according to claim 7 , wherein
said pixel electrodes have a prescribed shape in plan view, and
a plurality of said dummy electrodes are so formed as to have the same shape as said pixel electrodes in plan view and to enclose said pixel electrodes.
9. The image sensor according to claim 8 , wherein
said first transistor is provided every said dummy electrode.
10. The image sensor according to claim 7 , wherein
four said dummy electrodes, having a rectangular shape in plan view, are formed along sides of a pixel array region provided with said pixel electrodes arranged in the form of a matrix.
11. The image sensor according to claim 7 , wherein
one said dummy electrode is so annularly formed as to enclose said pixel electrodes arranged in the form of a matrix.
12. The image sensor according to claim 1 , further comprising a second transistor connected to said pixel electrodes, wherein
the gate electrode of said first transistor is formed by the same layer as the gate electrode of said second transistor.
13. The image sensor according to claim 1 , so formed as to control the frequency for ejecting charges flowing into said dummy electrode in an imaging period.
14. The image sensor according to claim 13 , so formed as to control the frequency for ejecting charges flowing into said dummy electrode in response to the quantity of charges ejected from said dummy electrode.
15. The image sensor according to claim 14 , further comprising:
a capacitor temporarily holding charges ejected from said dummy electrode, and
a determination circuit for determining the quantity of charges held in said capacitor.
16. The image sensor according to claim 1 , further comprising a transparent electrode formed on said photoelectric conversion film for receiving a negative potential.
17. The image sensor according to claim 1 , further comprising a third transistor for amplifying charges flowing into said pixel electrodes.
18. The image sensor according to claim 1 , so formed that the interval between said pixel electrodes and said dummy electrode is identical to the interval between said plurality of pixel electrodes.