Temperature control device for head of thermal printer

• US 4,651,166 A
• Filed: 05/12/1986
• Issued: 03/17/1987
• Est. Priority Date: 05/10/1985
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Katsuragi, Shigeru
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): Preston, Gerald E.
• Application Number:
  US06/862,047
• Time in Patent Office: 309 Days
• Field of Search: 346/76 PH, 400/120
• US Class Current: 347/194
• CPC Class Codes: B41J 2/375 Protection arrangements against overheating

Abstract

In a thermal printer, a difference between an actual temperature of a head of the printer and a sensed temperature is compensated for to accurately control temperature of the head. A rate of variation in the temperature of the head which has occurred within a predetermined period of time is detected so that an overheat temperature of the head is set up according to the detected rate.

Claims

1. A device for controlling temperature of a head of a thermal printer by compensating for a difference between an actual temperature of the head and a sensed temperature, comprising:

temperature sensing means for sensing an actual temperature of the head to produce the actual temperature as first temperature data; and

temperature compensating means for detecting a rate of variation of the first temperature data which has occurred within a predetermined period of time, compensating the first temperature data based on the detected rate, and producing the compensated first temperature data as second temperature data.

2. A device as claimed in claim 1, wherein the second temperature data is produced by adding to the first temperature data an amount of variation which has occurred during the predetermined period of time.

3. A device as claimed in claim 2, wherein the temperature compensating means comprises means for storing the first temperature data and means for comparing the first and the second temperature data to each other.

4. A device as claimed in claim 1, further comprising control means for generating a control signal to control the head responsive to the second temperature data.