Offset printer

1. An offset printer comprising:

a printing roller;

a coating unit configured to apply a printing substance to the printing roller;

a patterning unit configured to pattern the printing substance applied to the printing roller from the coating unit;

a printing unit that transfers the patterned printing substance to a printing medium; and

a cleaning unit configured to clean the printing substance remaining on the printing roller by a dry cleaning method;

wherein the coating unit includes a first drier configured to dry the printing substance applied to the printing roller; and

wherein the cleaning unit includes a cleaning plate configured to clean the printing roller.

2. The offset printer of claim 1 , wherein the cleaning unit further comprises

a cleaning stage configured to support the cleaning plate.

3. The offset printer of claim 2 , wherein the cleaning plate includes a metal or PDMS (polydimethylsiloxane).

4. The offset printer of claim 2 , wherein the cleaning unit further comprises a sweeper configured to remove the printing substance from the cleaning plate.

5. The offset printer of claim 1 , wherein the cleaning unit comprises a cleaning roller configured to clean the printing roller.

6. The offset printer of claim 5 , wherein the cleaning roller comprises a blanket roller.

7. The offset printer of claim 6 , wherein the blanket roller comprises a metal material, a ceramic material, a Teflon material, or a plastic material.

8. The offset printer of claim 5 , wherein the cleaning unit further comprises:

a cleaning bath containing a cleaning liquid for cleaning the cleaning roller; and

a second drier configured to dry clean liquid applied to the cleaning roller.

9. The offset printer of claim 8 , wherein the cleaning unit further comprises a cover configured to cover an upper end of the cleaning bath and selectively expose the cleaning roller to the cleaning liquid contained in the cleaning bath.