Thermal print head and thermal printer

Patent metadata

Field	Value
Publication number	US-9827782-B2
Application number	US-201515112662-A
Country	US
Kind code	B2
Filing date	Jan 16, 2015
Priority date	Jan 21, 2014
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A thermal print head includes a base member, an electrode layer formed on the base member, and a resistor layer formed on the base member. The electrode layer includes a common electrode and individual electrodes. The resistor layer includes heating units aligned in a main scanning direction. The heating units each include a first heating element and a second heating element spaced apart from each other. The first heating element and the second heating element are electrically connected to the common electrode and one of the individual electrodes to which the first heating element is electrically connected.

First claim

The invention claimed is:

1. A thermal print head comprising:
a base member;
an electrode layer formed on the base member; and
a resistor layer formed on the base member,
wherein the electrode layer includes a common electrode and individual electrodes,
the resistor layer includes heating units aligned in a main scanning direction,
each of the heating units includes a first heating element and a second heating element spaced apart from each other,
the first heating element is electrically connected to the common electrode and one of the individual electrodes,
the second heating element is electrically connected to the common electrode and the one of the individual electrodes that is electrically connected to the first heating element,
the common electrode and the one of the individual electrodes that is electrically connected to the first heating element are spaced apart from each other in a sub scanning direction by a first distance with the first heating element disposed therebetween,
the first and second heating elements include first and second edges, respectively,
the first edge of the first heating element and the second edge of the second heating element are spaced apart from each other in the main scanning direction by a second distance, and
the one of the individual electrodes that is electrically connected to the first heating element includes a portion that has a size in the main scanning direction that is smaller than the second distance over a length in the sub scanning direction that is larger than the first distance.

2. The thermal print head according to claim 1 , wherein the first heating element and the second heating element are electrically connected in parallel.

3. The thermal print head according to claim 1 , wherein the individual electrodes are aligned in the main scanning direction and arranged adjacent to one another.

4. The thermal print head according to claim 1 , wherein a first groove is formed between the first heating element and the second heating element, the first groove penetrating through the resistor layer.

5. The thermal print head according to claim 4 , wherein the first groove penetrates through a part of the electrode layer.

6. The thermal print head according to claim 4 , wherein the first groove penetrates through the common electrode and the one individual electrode.

7. The thermal print head according to claim 6 , wherein a portion of the first groove penetrating through the common electrode has a size of 5 to 30 μm in the sub scanning direction.

8. The thermal print head according to claim 6 , wherein a portion of the first groove penetrating through the one individual electrode has a size of 5 to 30 μm in the sub scanning direction.

9. The thermal print head according to claim 4 , wherein the first groove extends in the sub scanning direction.

10. The thermal print head according to claim 9 , wherein the first groove is greater in length in the sub scanning direction than the first heating element.

11. The thermal print head according to claim 4 , wherein a second groove is formed between two adjacent ones of the heating units, the second groove penetrating through the resistor layer.

12. The thermal print head according to claim 11 , wherein the second groove penetrates through a part of the electrode layer.

13. The thermal print head according to claim 11 , wherein the second groove is greater in size in the sub scanning direction than the first groove.

14. The thermal print head according to claim 11 , wherein the second groove includes a narrowed portion and a widened portion,
the narrowed portion is smaller in width in the main scanning direction than the widened portion, and
the narrowed portion overlaps with an entirety of the first groove in the sub scanning direction.

15. The thermal print head according to claim 1 , wherein the common electrode includes a common electrode strip-shaped portion extending in the main scanning direction, and
the individual electrodes are opposed to the common electrode strip-shaped portion in the sub scanning direction with respect to the heating units.

16. The thermal print head according to claim 15 , wherein the common electrode includes protruding portions each extending from the common electrode strip-shaped portion, and
each of the protruding portions is in contact with one of the heating units.

17. The thermal print head according to claim 16 , wherein each of the protruding portions includes a common electrode base portion, a first common electrode joint portion, and a second common electrode joint portion,
the common electrode base portion is connected to the common electrode strip-shaped portion,
the first common electrode joint portion and the second common electrode joint portion are branched from the common electrode base portion,
the first common electrode joint portion is in contact with the first heating element, and
the second common electrode joint portion is in contact with the second heating element.

18. The thermal print head according to claim 16 , wherein each of the protruding portions each includes a constricted portion.

19. The thermal print head according to claim 1 , wherein each of the individual electrodes includes an individual electrode base portion, a first individual electrode joint portion, and a second individual electrode joint portion,
the first individual electrode joint portion and the second individual electrode joint portion are branched from the individual electrode base portion,
the first individual electrode joint portion is in contact with the first heating element, and
the second individual electrode joint portion is in contact with the second heating element.

20. The thermal print head according to claim 19 , wherein each of the individual electrodes includes a constricted portion.

21. The thermal print head according to claim 1 , wherein the resistor layer is disposed between the base member and the electrode layer.

22. The thermal print head according to claim 1 , wherein
a size of the first heating element in the main scanning direction is smaller than the first distance.

23. The thermal print head according to claim 22 , wherein the first distance is 60 to 100 μm, and the size of the first heating element in the main scanning direction is 40 to 60 μm.

24. The thermal print head according to claim 1 , wherein each of the heating units includes at least one additional heating element,
the at least one additional heating element is spaced apart from both of the first heating element and the second heating element in the main scanning direction, and
the at least one additional heating element is smaller in resistance than each of the first heating element and the second heating element.

25. The thermal print head according to claim 1 , further comprising a heat storage region disposed between the base member and the heating units.

26. The thermal print head according to claim 25 , wherein the heat storage region is made of a glass material.

27. The thermal print head according to claim 1 , further comprising an auxiliary conductive layer overlapping with the common electrode in plan,
wherein the auxiliary conductive layer is disposed between the electrode layer and the base member.

28. The thermal print head according to claim 27 , wherein the auxiliary conductive layer is made of Ag

Assignees

• Rohm Co Ltd

Inventors

• Nishi Koji

Classifications

• B41J2/33515

  Heater layers · CPC title

• B41J2/3351 Primary

  Electrode layers · CPC title

• B41J2/3354

  characterised by geometry · CPC title

• B41J2/3357

  Surface type resistors · CPC title