Canon BJC-8500 Service Manual

Also see for BJC-8500: User manual

Contents

5.2.3 Ink-out detection1) OperationThe ink sensor unit installed on the purge unit comprises an LED and photo-transistor. The light emitted from the LED enters the prism formed on the base ofthe ink tank at an angle of incidence of 45°. When the ink tank's ink compartmentcontains ink, the incident light is partially refracted due to the slight differencebetween the refractive indices of the ink tank (plastic) and the ink, and the amountof light entering the photo-transistor decreases. Whereas, when the ink tank's inkcompartment runs out of ink, incident light is totally reflected at the angle ofincidence of 45° due to the large difference between the refractive indices of the inktank (plastic) and the air, and the amount of light entering the photo-transistorincreases. The presence of ink in the ink tank's ink compartment is detected by thestrength of this incident light (voltage value after photo-voltaic conversion by thephoto-transistor) to this photo-transistor.2) Ink-out warning/ink-out errorWhen the printer has detected that the ink tank's ink compartment has run out ofink, the "ink-out" warning is displayed on the status monitor of the printer driver.The dot counter then starts counting the number of dots ejected. After the presetdot count is exceeded, the "ink-out" error (operator call) is generated and the printerstops printing. At this time, follow the instructions displayed on the host computer,and replace the ink tank with a new tank.You can, however, ignore this error and continue printing by pressing theRESUMEbutton to reset the dot counter. After you have pressed theRESUME button, the dotcounter then starts counting the number of dots ejected. After the preset dot countis exceeded, the "ink-out" error (operator call) will again be generated and the printerstops printing.Part 4: Technical Reference BJC-85004-46Figure 4-42 Principle of Ink-out DetectionAirPrismInk Compartment SpongeInk SensorInk Tank(Plastic)LED LEDPhoto-transistorInk Sensor(1) Ink Present (2) Ink-outInk Tank(Plastic)45°InkPhoto-transistor45°