CHARGE CONTROL AGENT FOR ELECTROPHORETIC DISPLAY

1 . A compound of the following formula:

(CH 3 ) 3 C—[—CH 2 —C(CH 3 ) 2 —] n -L-NR 1 R 2 R 3+ X −

wherein L is a linking chain;

R 1 , R 2 and R 3 are independently an alkyl of 1-4 carbon atoms; and

X − is a counter ion.

2 . The compound of claim 1 , wherein L is a saturated or unsaturated alkylene or amide-alkylene chain of 2 to 6 carbon atoms

3 . The compound of claim 2 , wherein L is —CRR—CR═CR—CRR—, —CRR—CRR—CRR— or —NHC(O)—CRR—CRR—CRR— wherein the R's are independently hydrogen or an alkyl of 1-4 carbon atoms.

4 . The compound of claim 3 , wherein L is —CH 2 —CH 2 —CH 2 —, —CH 2 —CH═CH—CH 2 —, —CH 2 —CH 2 —CH(CH 3 )—, —CH 2 —CH(CH 3 )—CH 2 — or —NHC(O)—CH 2 —CH 2 —CH 2 —.

5 . The compound of claim 4 , wherein L is —CH 2 —CH 2 —CH(CH 3 )—.

6 . The compound of claim 1 , wherein R 1 , R 2 and R 3 are methyl.

7 . The compound of claim 1 , wherein X − is F − , Cl − , Br − , R′SO 3 − , R′SO 4 − or R′CO 3 − , wherein R′ is an alkyl of 1-4 carbon atoms or an aryl of 6 to 18 carbon atoms optionally substituted with an alkyl of 1-4 carbon atoms.

8 . The compound of claim 7 , wherein X − is R′SO 4 − wherein R′ is an alkyl of 1-4 carbon atoms.

9 . The compound of claim 8 , wherein R′ is methyl.

10 . The compound of claim 1 , wherein X − is R′SO 3 − wherein R′ is a phenyl optionally substituted with an alkyl of 1-4 carbon atoms.

11 . An electrophoretic fluid comprising charged pigment particles and a compound of claim 1 in a solvent or solvent mixture.

12 . The fluid of claim 11 , wherein the compound of claim 1 has L being —CH 2 —CH 2 CH(CH 3 )—, R 1 , R 2 and R 3 being methyl and the counter ion being R′SO 4 − wherein R′ is methyl.

13 . The fluid of claim 11 , wherein the concentration of the compound of claim 1 is in the range of 0.05% to 0.6% by weight.