Canon BJC 50 Service Manual - Page 93

BJC-50 1.4 Print Drive Part 4: Technical Reference The printer outputs control signals from the ASIC's printer controller to the BJ head to eject ink from the BJ head for printing. The control signals consist of the print control signal for ejecting ink from the head's nozzles and the temperature control signal for adjusting the head's temperature so that the amount of ink ejected is uniform. To archive optimum printing, both these control signals are optimized by the printer controller and sent from the carriage ribbon cable's signal contacts to the BJ head. The drive frequency varies depending on the printing mode and BJ cartridge type. 1.4.1 Printing drive control a) Black BJ cartridge drive control The black BJ cartridge drive control is executed by dividing the head's 128 nozzles into 8 blocks (16 nozzles each). These blocks are further divided into odd and even blocks (8 nozzles each). The odd blocks eject ink simultaneously and the even blocks do so as well. The control signals for the former are the block enable 0, 1, and 2 signals (BENB 0, 1, 2) and for the latter the signals are the even/odd enable signals (Even/Odd ENB). The heat enable A and D (HENB A, D), which are the heater drive control signals for ejecting the ink, comprise of a prepulse and main pulse. To constantly archive optimum ink ejection, the internal conditions such as the head's rank, printer temperature, and head temperature are monitored and the heater drive pulse width is varied before the pulse is output. Furthermore, the print drive signal from the printer controller is transferred to the BJ head's shift resistor according to the HLATCH timing. The printing drive signal (HDATA) is latched and when the print control and heater drive control signals are output together, the heater for the applicable nozzles is driven and the ink is ejected. b) Color BJ cartridge (Large/Small Drop) drive control The two-size droplet type color BJ cartridge has a print head with 136 nozzles and each nozzle has two heaters, one infront of the other, that regulate the ejection of large and small ink droplets. The 136 nozzles are divided into 8 functional blocks, each block consisting of 16 nozzles. Ink is ejected consecutively from each block. The order and selection of nozzles to be used are controlled by BLOCK ENABLE signals (BENB 0,1,2) and the EVEN/ODD ENABLE signal (Even/Odd ENB). HEAT ENABLE signals (HENB A,B,C,D) control the heater boards. BE1 BE2 BE3 BE4 BE5 BE6 BE7 BE8 O E O E O E O E O E O E O E O E A A A A A A A A A A A A A A A A B B B B B B B B B B B B B B B B A A A A A A A A A A A A A A A A B B B B B B B B B B B B B B B B 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 BE1 to BE 8 : Block Enable 1 to 8 E : Even Enable O : Odd Enable A : Heat Enable 0 B : Heat Enable 1 Figure 4-3 Print Sequence (Black BJ Cartridge in HQ Mode) 4-5 : :