Image forming apparatus performing double-sided printing

• US 20060024108A1
• Filed: 07/06/2005
• Published: 02/02/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: S-Printing Solution Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Han, Dong-hun, Son, Myung-Bo, Lee, Yong-duk
• Granted Patent: US 7,431,520 B2
• Time in Patent Office: Days
• US Class Current: 400/120.170
• CPC Class Codes: B41J 13/009 Diverting sheets at a section where at least two sheet conveying paths converge, e.g. by a movable switching guide that blocks access to one conveying path and guides the sheet to another path, e.g. when a sheet conveying direction is reversed after printing on the front of the sheet has been finished and the sheet is guided to a sheet turning path for printing on the back
• CPC Class Codes: B41J 13/14 Aprons or guides for the printing section
• CPC Class Codes: B41J 2/325 by selective transfer of ink from ink carrier, e.g. from ink ribbon or sheet
• CPC Class Codes: B41J 3/60 for printing on both faces of the printing material

Abstract

An image forming apparatus is provided and includes a platen roller and a thermal printing head. The thermal printing head is elastically biased toward the platen roller and rotates about a pivot of the platen roller for moving between first and second positions to faces first and second surfaces of a medium. A transfer portion has driving and driven rollers which are rotatably engageable with each other to transfer the media. A guiding unit reduces a difference of media transfer force of the transfer portion when the thermal printing head is respectively located in the first and second positions.

Claims

1. An image forming apparatus comprising:

a platen roller;

a thermal printing head being elastically biased toward the platen roller and being rotatable about a pivot of the platen roller for moving between first and second positions to face first and second surfaces of a medium;

a transfer portion which includes driving and driven rollers being rotatably engageable with each other to transfer the media; and

a guiding unit to reduce a difference of a media transfer force of the transfer portion, when the thermal printing head is respectively located in the first and second positions, by controlling an entry angle by which the media enters the transfer portion.

2. The apparatus of claim 1, wherein the guiding unit controls the entry angle by which the media enters the transfer portion so that a contact area of the media and the driving roller is the same regardless of whether the thermal printing head is located in the first position or the second position.

3. The apparatus of claim 2, wherein the driving roller and the driven roller engage with each other to form a predetermined contact nip, and the guiding unit guides the media so that the media contacts the driving roller on a width of the contact nip.

4. The apparatus of claim 1, wherein:

the driving roller and the driven roller engage with each other to form a predetermined contact nip, and the driving roller is located in the first position from the contact nip and the driven roller is located in the second position from the contact nip, and

the guiding unit includes one or more first guiding element which guides the media to reduce a winding angle by which the media winds around the driving roller when the TPH is located in the first position.

5. The apparatus of claim 4, wherein the first guiding element is a roller which contacts the media and rotates.

6. The apparatus of claim 4, wherein the guiding unit further includes one or more second guiding element which guides the media to reduce a winding angle by which the media winds around the driven roller when the TPH is located in the second position.

7. The apparatus of claim 6, wherein the second guiding element is a roller to contact the media and rotates.

8. The apparatus of claim 1, wherein the media is a color printing media on which ink layers representing different colors from each other are formed on both sides, and when printing on the both sides is finished, images having different colors from each other are overlapped to form a color image.

9. An image forming apparatus comprising:

a platen roller;

a thermal printing head being elastically biased toward the platen roller and being rotatable about a pivot of the platen roller for moving between first and second positions to face first and second surfaces of a medium;

a driving roller and a driven roller being rotatably engageable with each other to form a contact nip having a predetermined width to transfer the media, and the driving roller is located in the first position from the contact nip and the driven roller is located in the second position from the contact nip; and

one or more first guiding elements to guide the media to reduce a winding angle by which the media winds around the driving roller when the thermal printing head is located in the first position.

10. The apparatus of claim 9, wherein the first guiding element is a roller to contact the media and rotates.

11. The apparatus of claim 9, further comprising one or more second guiding elements to guide the media to reduce a winding angle by which the media winds around the driven roller when the TPH is located in the second position.

12. The apparatus of claim 11, wherein the second guiding element is a roller to contact the media and rotates.

13. The apparatus of claim 9, wherein the media is a color printing media on which ink layers representing colors different from each other are formed on both sides of a substrate, and when printing on both sides is finished, images having different colors are overlapped to form a color image.