Apparatus for controlling ribbon tension in a thermal printer

• US 6,315,471 B1
• Filed: 10/13/1999
• Issued: 11/13/2001
• Est. Priority Date: 08/21/1999
• Status: Expired due to Fees

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chung, Chuan-Yuan, Hsieh, Chu-Cheng
• Primary Examiner(s): COLILLA, DANIEL JAMES
• Application Number:
  US09/417,330
• Time in Patent Office: 762 Days
• Field of Search: 400/234, 400/120.02, 400/120.04, 400/223, 347/215, 347/172, 347/177, 347/178, 347/217
• US Class Current: 400/234
• CPC Class Codes: B41J 35/08 with tensioning arrangements

Abstract

The invention described a thermal printer. The thermal printer has a supply reel, a take-up and a pair of motors. Each motor connects with the supply reel and the take-up reel, respectively. A detecting apparatus detects ribbon and the reel parameters while initializing the thermal printer. A memory stores a transforming table which can obtain the driving pulse width of each motor from a radius of the supply reel, a radius of the take-up reel and the ribbon tension. A control apparatus drive each motor with different pulse width according to parameters detected by the detecting apparatus and the transforming table. A thermal print head performs a printing process.

Claims

1. An apparatus for controlling ribbon tension, which apparatus is applied in a thermal printer, the apparatus for controlling ribbon tension comprising:

a pair of reels comprising a supply reel and a take-up reel;

a ribbon that is unwound from one reel and collected on another reel;

a pair of motors respectively connected to the reels;

a detecting apparatus that detects parameters of the ribbon and the reels while initializing the thermal printer; and

a control apparatus that stores a transforming table between ribbon tension and pulse width of each motor such that each motor is driven by a different pulse width as a function of the parameters detected by the detecting apparatus and the transforming table.

2. The apparatus of claim 1, wherein the motors include direct current motors.

3. The apparatus of claim 1, wherein the detecting apparatus further comprises:

a ribbon sensor for detecting ribbon parameters; and

a reel sensor detecting an angular velocity of the supply reel.

4. The apparatus of claim 1, wherein the control apparatus further comprises:

a motor controller controlling the motors.

5. A thermal printer, comprising:

a pair of reels comprising a supply reel and a take-up reel;

a ribbon that is unwound from one reel and collected on another reel;

a pair of motors respectively connected to the reels;

a capstan apparatus;

a detecting apparatus that detects parameters of the ribbon and the reels while initializing the thermal printer;

a memory that stores a transforming table between ribbon tension and pulse width of each motor;

a control apparatus that respectively drives the motors with different pulse widths as a function of the parameters detected by the detecting apparatus and the transforming table; and

a thermal print head for performing a printing process.

6. The printer of claim 5, wherein the motors include direct current motors.

7. The printer of claim 5, wherein the detecting apparatus further comprises:

a ribbon sensor detecting ribbon parameters; and

a reel sensor detecting an angular velocity of the supply reel.

8. The printer of claim 5, wherein the control apparatus further comprises:

a thermal print head controller controlling the thermal print head; and

a motor controller driving the motors.

9. The printer of claim 5, wherein the capstan apparatus further comprises:

a capstan roller; and

a pinch roller.

10. A method for controlling ribbon tension, which method is applied in a thermal printer comprising a supply reel and a take-up reel, each reel connecting to a motor, the method for controlling ribbon tension comprising the steps of:

establishing a transfer relationship between ribbon tension and pulse width of each motor, wherein a transforming table is stored in the thermal printer;

calculating a radius of the supply reel and a radius of the take-up reel while the thermal printer performs an initializing process; and

controlling ribbon tension by driving the motors with different pulse widths, respectively, as a function of the radius of the supply reel, the radius of the take-up reel and the transforming table to control ribbon tension.

11. The method of claim 10, wherein the thermal printer further comprises:

a ribbon sensor detecting ribbon parameters; and

a reel sensor detecting an angular velocity of the supply reel.

12. The method of claim 10, wherein the radius of the supply reel is calculated by detecting the angular velocity of the supply reel.

13. A method for controlling ribbon tension, which is applied in a thermal printer comprising a supply reel and a take-up reel, each reel connecting with a motor, with a memory storing a transforming table between ribbon tension and pulse width of each motor, the method for controlling ribbon tension comprising the steps of:

performing an initializing process to obtain a radius of the supply reel and a radius of the take-up reel;

obtaining a pulse width of each motor as a function of the radius of the supply reel, the radius of the take-up reel and the transforming table; and

performing a printing process to print a color on a print medium by respectively driving each motor with the pulse width.

14. The method of claim 13, wherein a preparation process is performed before the printing process.

15. The method of claim 13, wherein an overprinting process is performed to print another color after the printing process.

16. The method of claim 13, wherein the print medium includes paper.

17. An apparatus for controlling ribbon tension, which apparatus is applied in a thermal printer, the apparatus for controlling ribbon tension comprising:

a pair of reels comprising a supply reel and a take-up reel;

a ribbon that is unwound from one reel and collected on another reel;

a pair of motors respectively connected to the reels;

a detecting apparatus, comprising a ribbon sensor and a reel sensor that respectively detect ribbon parameters and angular velocity of the supply reel while initializing the thermal printer; and

a control apparatus that stores a transforming table between ribbon tension and pulse width of each motor, such that each motor is driven by a different pulse width as a function of the parameters detected by the detecting apparatus and the transforming table.

18. The apparatus of claim 17, wherein the motors include direct current motors.

19. The apparatus of claim 17, wherein the control apparatus further comprises a motor controller controlling the motors.

20. A thermal printer, comprising:

a pair of reels comprising a supply reel and a take-up reel;

a ribbon that is unwound from one reel and collected on another reel;

a pair of motors respectively connected to the reels;

a capstan apparatus;

a detecting apparatus comprising a ribbon sensor and a reel sensor that respectively detect parameters of the ribbon and angular velocity of the supply reel while initializing the thermal printer;

a memory that stores a transforming table between ribbon tension and pulse width of each motor;

a control apparatus that respectively drives the motors with different pulse widths as a function of the parameters detected by the detecting apparatus and the transforming table; and

a thermal print head for performing a printing process.

21. The printer of claim 20, wherein the motors include direct current motors.

22. The printer of claim 20, wherein the control apparatus further comprises:

a thermal print head controller controlling the thermal print head; and

a motor controller driving the motors.

23. The printer of claim 20, wherein the capstan apparatus further comprises:

a capstan roller; and

a pinch roller.