| 摘要 |
PURPOSE:To maintain appropriate level of toner concn. by controlling a travel means based on judgement for the time of exchange of a protective sheet by a judging means. CONSTITUTION:The detecting surface 11 of a toner concn. sensor 10 is covered with the protective sheet 12a. The sheet 12a is formed in film shape, and is suspended between a rewind roller 16 and a delivery roller 17, and is sent out sequentially, and is exchanged with a new sheet 12a. The time of exchange of the sheet 12a is decided by counting the number of times of copying with the judging means 13 and send a signal to a control means 14. Then, a motor 15 that is the travel means is rotated with the command of the control means 14. Thereby, rollers 17, 18 are rotated, and the sheet is exchanged with the new sheet 12a, therefore, the toner concn. can be accurately detected, and the appropriate level of toner concn. can be maintained. |
