Image forming apparatus using thermal print head

• US 20070025789A1
• Filed: 04/26/2006
• Published: 02/01/2007
• Est. Priority Date: 07/26/2005
• Status: Abandoned Application

• Current Assignee: S-Printing Solution Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: S-Printing Solution Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Lee, Yong-duk
• Application Number:
  US11/411,025
• Publication Number:
  US 20070025789A1
• Time in Patent Office: Days
• US Class Current: 400/188
• CPC Class Codes: B41J 13/0045 concerning sheet refeed sections of automatic paper handling systems, e.g. intermediate stackers printing on both faces B41J3/60
• CPC Class Codes: B41J 13/076 Construction of rollers; Bearings therefor
• CPC Class Codes: B41J 13/103 for the sheet feeding section
• CPC Class Codes: B41J 13/106 for the sheet output section
• CPC Class Codes: B41J 3/60 for printing on both faces of the printing material

Abstract

An image forming apparatus using a thermal printing head, the image forming apparatus including a printing unit having a thermal printing head to print an image by applying heat to a medium and a platen roller facing the thermal printing head to support the medium, a conveying unit to convey the medium at a predetermined printing speed, and a guide roller disposed between the conveying unit and the printing unit to guide the medium, the guide roller having a curved portion formed in a width direction of the medium.

Claims

1. An image forming apparatus, comprising:

a printing unit having a thermal printing head to print an image by applying heat onto a medium, and a platen roller facing the thermal printing head to support the medium;

a conveying unit to convey the medium at a predetermined printing speed; and

a guide roller disposed between the conveying unit and the printing unit to guide the medium, the guide roller having a curved portion formed in a width direction of the medium.

2. The apparatus according to claim 1, wherein the curved portion has a positive curvature when a heating line of the thermal printing head is convex toward the guide roller, and a negative curvature when the heating line of the thermal printing head is concave toward the guide roller.

3. The apparatus according to claim 2, wherein the thermal printing head is transferable to a first position facing a first surface of the medium, and a second position facing a second surface opposite to the first surface.

4. The apparatus according to claim 3, wherein the thermal printing head is transferable to the first and second positions by revolving around the platen roller.

5. The apparatus according to claim 4, wherein the guide roller includes first and second guide rollers to guide the medium when the thermal printing head is located at the first and second positions, respectively.

6. An image forming apparatus, comprising:

a printing unit including a thermal print head to form an image on a medium as the medium is conveyed therethrough and to heat the medium according to image information; and

a guide unit to bias the medium along a widthwise direction as the medium is being conveyed so that a curvature of the width of the medium corresponds with a curvature of a line in which the image information is heated.

7. The apparatus according to claim 6, wherein:

the guide unit comprises at least one guide roller curved along a lengthwise direction thereof to transform an area on the medium upon which the printing unit exerts a force to have a shape that is substantially the same as a shape of the heating line.

8. The image forming apparatus according to claim 7, wherein the at least one guide roller is concave or convex along a lengthwise direction thereof.

9. The image forming apparatus according to claim 7, wherein the at least one guide roller comprises a plurality of guide rollers.

10. The image forming apparatus according to claim 9, wherein:

at least one of the plurality of guide rollers is concave along a lengthwise direction thereof; and

at least another of the plurality of guide rollers is convex along a lengthwise direction thereof.

11. The image forming apparatus according to claim 7, wherein:

the heating line is curved in a lengthwise direction of the thermal print head; and

a distance between a center portion of the heating line and an edge portion of the heating line in a conveying direction is less than about 100 μ

m.

12. The image forming apparatus according to claim 7, wherein the printing unit further comprises:

a platen roller to form a printing nib with the thermal print head; and

an elastic member to push the thermal print head toward the platen roller to exert the force on the medium and to form the printing nib.

13. The image forming apparatus according to claim 7, wherein the printing unit further comprises:

a conveying unit to convey the medium to and from the thermal print head.

14. The image forming apparatus according to claim 12, wherein the thermal print head is rotatable around the platen roller.

15. A conveying unit useable in an image forming apparatus having a thermal print head, the conveying unit comprising:

a conveying member to convey a printing medium to and from the thermal print head; and

a guide member to bias the printing medium along a widthwise direction as the medium is being conveyed so that a curvature of the width of the medium corresponds with a curvature of a heating line on the thermal print head.

16. A method of printing an image using an image forming apparatus having a thermal print head, comprising:

forming an image on a medium as the medium is conveyed through the thermal print head and heating the medium according to image information; and

biasing the medium along a widthwise direction as the medium is being conveyed so that a curvature of the width of the medium corresponds with a curvature of a line in which the image information is heated.

17. The method according to claim 16, wherein:

the forming of the image on the medium comprises forming an image on a first surface of the medium as the medium is conveyed through the thermal print head and heating the first surface of the medium according to the image information; and

the biasing of the medium comprises transforming an area on the first surface of the medium upon which the printing unit exerts a force to have a shape that is substantially the same as a shape as the heating line.

18. The method according to claim 17, further comprising:

rotating the thermal print head 180°

;

forming an image on a second surface of the medium as the medium is conveyed through the thermal print head and heating the second surface of the medium according to the image information; and

transforming an area on the second surface of the medium upon which the printing unit exerts a force to have a shape that is substantially the same as the shape of the heating line.

19. The method according to claim 17, wherein the heating line is curved in a length direction.

20. The method according to claim 19, wherein a distance between a center portion of the curved heating line and an edge portion of the curved heating line is less than about 100 μ

m.

21. The method according to claim 19, wherein the curved heating line has a convex or a concave shape.

22. The method according to claim 18, further comprising ejecting the medium having the printed images on the first and second surfaces thereof from the image forming apparatus.