Thermal printer

• US 5,694,159 A
• Filed: 08/21/1996
• Issued: 12/02/1997
• Est. Priority Date: 03/25/1994
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Sato
• Original Assignee: Kabushiki Kaisha Sato
• Inventors: Takeuchi, Sakae, Kajiya, Hiroshi
• Primary Examiner(s): TRAN, HUAN HUU
• Application Number:
  US08/701,040
• Time in Patent Office: 468 Days
• Field of Search: 347/197, 347/222, 406/120.16
• US Class Current: 347/197
• CPC Class Codes: B41J 2/32 using thermal heads
• CPC Class Codes: B41J 25/316 with tilting motion mechanisms relative to paper surface

Abstract

In a thermal printer having a printer frame to which the thermal print head is swingable attached and supported on a print head holder, the orientation of the print head with reference to a platen roller is set and the print head is permitted to move with reference to the platen roller without changing their orientations. An engagement pin on the printer frame receives a fourth engaging member on the end of the thermal print head holder. A positioning pin on the print head holder is received in a positioning hole in the print head holder mounting plate. Fixing pins at each side of the first positioning pin are received in fixing holes in the mounting plate and are held there by fixing elements. The engaging pin and engaging member permit the print head holder to move with reference to the platen roller to accommodate different thickness papers.

Claims

1. A thermal printer comprising:

a main frame;

a rotatable platen roller supported on the main frame;

first print head engaging means on the main frame;

a print head frame mounted on the main frame and movable with respect to the main frame toward the platen roller for printing and openable away from the main frame;

a thermal print head detachably mounted on the openable head frame;

the print head including a holder having an end and a second engaging means at the end of the holder;

a first positioning member located generally toward the center of the holder; and

a first fixing member located to a side of the first positioning member;

a print head holder mounting plate connectable to the head frame and including a second positioning member which corresponds in position to the first positioning member so that they might be engaged;

a second fixing member in position to engage the first fixing member;

the first and second engaging means, the first and second positioning members and the first and second fixing members all being respectively so positioned that upon respective engagement of each of the first and second engaging means, the first and second positioning members and the first and second fixing members, the print head is positioned relative to the platen roller for bringing the print head into contact with the platen roller to print paper between them;

the first and second engaging means being structured and arranged to enable relative positioning of the print head above the platen roller for varying thickness paper to be printed;

the first and second positioning members being engagable and being structured and arranged for setting the contact position of the print head on the platen roller and the first and second fixing members being engagable and being structured and arranged for setting a fixed position between the print head and the print head holder mounting plate and for urging the print head against the platen roller.

2. The thermal printer of claim 1, wherein there is a respective first engaging means at each end of the main frame and a respective second engaging means at each end of the holder for engaging the respective first engaging means there.

3. The thermal printer of claim 2, wherein there is a respective first fixing member at each side of the first positioning member on the print head holder and a second fixing member at each side of the second positioning member and in a position to correspond to the respective first fixing member.

4. The thermal printer of claim 3, wherein one of the first and second positioning members comprises a pin on one of the thermal print head holder and the head holder mounting plate, and the other of the first and second positioning members comprises a hole for receiving the pin enabling play in spacing between the print head holder and the head holder mounting plate but prohibiting shifting with reference to the position of the platen roller.

5. The thermal printer of claim 4, wherein one of the first and second fixing members comprises a respective projecting element and the other comprises a hole for receiving a projecting element;

means on the projecting element for being fixed to the other of the print head holder and head holder mounting plate for fixing them against shifting in position relative to the platen roller while permitting adjustment of the spacing between the print holder and the mounting plate.

11. The thermal printer of claim 5, wherein a compression spring is provided on the projecting element for urging the print head against the platen roller.

6. A thermal printer comprising

a main frame;

a rotatable platen roller supported on the main frame;

first and second print head engaging members on the main frame;

a print head frame mounted on the main frame and movable with respect to the main frame toward and away from the platen roller;

a respective engaging pin at each side of the main frame;

a thermal print head mounted on the print head frame;

the thermal print head including a holder having a respective engaging member at each end thereof in position to correspond with the respective engaging pins at the sides of the main frame when the holder is moved to the respective engaging pin;

a positioning member located generally in the center of the holder;

a respective fixing member at each side of the positioning member on the holder;

a holder mounting plate having a respective positioning hole thereon in a position corresponding to that of the positioning member when the holder mounting plate and the holder are brought together;

the holder mounting plate further having a respective fixing hole therein on each side of the positioning hole in a position corresponding to that of the respective fixing member on the print head holder, such that when the holder and the holder mounting plate are moved together, the positioning member is received in the positioning hole for positioning the contact location of the printing head on the platen roller and the fixing members are received in the fixing holes for fixing the orientation of the holder with respect to the holder mounting plate thereof;

the respective engaging pins engaging the engaging members for relatively positioning the plate roller and the print head and allowing there spacing apart dependent upon the paper that is printed between them.

7. The thermal printer of claim 6, wherein each of the engaging members is comprised of a fork including an engagement opening between the arms of the fork and the engaging pin on the printer frame is received between the arms of the fork such that when the print head is brought into contact with the platen roller, the print head is movable and guided by the engaging members for enabling adjustment of the spacing of the print head from the platen roller depending upon the paper therebetween without change to the orientation of the print head with reference to the platen roller.

8. The thermal printer of claim 7, wherein the engaging members are symmetrically located with respect to the positioning member on the head holder across the width of the print head.

9. The thermal printer of claim 6, wherein the engaging members are symmetrically located with respect to the positioning member on the head holder across the width of the print head.

10. The thermal printer of claim 9, further comprising means on the holder mounting plate for engaging the fixing members when they are installed at the holder mounting plate for holding the fixing members against moving out of engagement with the holder mounting plate.

12. The thermal printer of claim 6, wherein each fixing member is provided with a respective compression spring to urge the print head against the platen roller.