COPYRIGHT © 2000 CANON INC. 2000 2000 2000 2000 CANON iR5000/iR6000 REV.0 JULY 2000CHAPTER 3 LASER EXPOSURE SYSTEM3-6 P3. Laser Driver Circuit3.1 Controlling the LaserThe laser driver circuit serves to drive the semiconductor laser in response to the laserdrive signal (LD) from the DC controller PCB.The following are control items associated with the laser driver circuit:1. Turning on/off laser light.2. Controlling the intensity of laser light (ACP control).3. Controlling the intensity of laser light to suit the surface potential of the drum.The following signals are used:[1] Laser drive signal.[2] Sample laser activation signal. Used to turn on laser light for an intensity sample (foreach scan).[3] Laser enable signal. Goes ‘0’ when the laser becomes ready after the Start key has beenpressed.[4] Laser write start signal. Used to start a laser write when paper reaches the laser writestart sensor (PS28), mounted in front of the registration roller.[5] The intensity of laser light is monitored while it is turned on to collect a sample; an ap-propriate value is fed back to the laser drive circuit.[6] The output is controlled so that the reference value from the DC controller (EEPROM)and the value returned as feedback will be identical.[7] Laser intensity reference signal. Used as the laser activation reference value, and is de-termined by potential control (EEPROM).Download Free Service Manual at http://printer1.blogspot.com
