Hewlett-Packard Product Number C6119A Maintenance Manual
Introduction This document acts as a guide for the maintenance and care of the Hewlett- Packard product number C6119A. The C6119A product is a disposable print cartridge system composed of a print head, a permanent clip and valve connection, and a black bulk ink supply. Background on Thermal Inkjet Technology The Hewlett-Packard product number C6119A is a cartridge used in a drop-ondemand thermal inkjet system. Inkjet systems fire small drops of ink to form text and images on various types of medium. Thermal inkjet uses a firing resistor to vaporize a small amount of ink. The vaporization process causes a small bubble to form. This bubble formation causes a small drop of ink to be forced out of the firing chamber through the nozzle. Figure 1 shows the major components of the thermal inkjet system. In the figure, the entire ink supply is located near the printhead of the pen. The C6119A product has a localized ink supply (supply is near the nozzles) as well as a bulk ink supply in the form of a reservoir. Back pressure is monitored in the local ink supply by a spring bag which prevents the ink from seeping out of the nozzles. The reservoir is not pressurized so it is necessary to handle the entire system with care. The filter screen keeps any large ink particles or air bubbles away from the firing chambers. Bubbles or particles in the firing chambers will prevent ink from coming out of the nozzle when the resistor heats up. There is a firing resistor, and an ink channel for every nozzle on the printhead. Ink Supply (Local or Bulk) Filter Screen Substrate Ink Barrier Orifice Surface Firing Resistor Nozzle Standpipe Section of a Printhead Figure 1: Anatomy of a Printhead Piezoelectric inkjet uses a piezoelectric crystal to push and pull a diaphragm under the firing chamber. The movement of the diaphragm creates a displacement in the ink chamber as shown in Figure 2. This displacement forces ink out of the nozzle and onto the paper.
Figure 2: Piezoelectric System Due to the advances in electronic circuitry, the necessary components to fire the resistor in thermal inkjet are a lot smaller than the mechanical components of the piezoelectric systems. This allows thermal inkjet printheads to have a high resolution without a large printhead. Reservoir/Pen System Care Set-up The back of the packaging shown in Figure 3 identifies the printhead as item number 1 and the Ink Reservoir as item number 2. When the Ink System box is open, the printhead (number 1) rests in the top of the box and the ink reservoir (number 2) is in the bottom of the box. Figure 3: Rear Panel of the Packaging The printhead should be removed from its packaging, and the reservoir should be slid out of the left side of the system packaging. Do not throw the packaging away until the system is installed in the printer. There are important directions on the packaging for attaching the pen to the reservoir. Do not attempt to remove the ink reservoir from its diamond-shaped box (see caution label on bottom panel of ink reservoir Figure 4).
Figure 4: Caution Statements Located on the Bottom of the Ink Reservoir It is also important that the ink reservoir does not get squeezed during the installation process. Squeezing the reservoir could cause ink to seep out of the printhead. The system can be connected with the help of the directions located on the printhead packaging. The location of these instructions can be seen in Figure 5. Figure 5: Valve Installation Directions Located on Printhead Box
The valve should be inserted into the clip on the pen until a clicking sound is heard or the operator feels the valve snap into place as illustrated in Figure 6. Figure 6: System Connection The valve and clip are symmetrical so there is no special orientation. Depending on the printer, it may be necessary to route the tube to keep it out of the way of the print mechanism. If this is the case, wait until all of the tubes are in place and the pen is ready to be placed into the printer before the tape is removed from the printhead. The tape will prevent the printhead from being damaged and it will also help to keep ink from leaking out of the printhead. If there is no need to route the tubes, remove the tape from the printhead and place it in the printer as quickly as possible. Note: it is important to take the tape off of the pen cartridge before the pen is placed in its holder. The pen will not make the proper electrical connection and the nozzles will not fire if the tape is still in tact. Handling Once the connection is made between the pen cartridge and the ink reservoir, it cannot be taken apart without damaging the system. It is best if the system is left in the machine, but sometimes this is not possible. When handling the system, it is important to keep the pen as close to the reservoir as possible without letting it go below the reservoir. Figure 7 demonstrates the proper orientation.
Figure 7: Handling Orientation If the pen is held more than 10 inches above the reservoir, air will be drawn into the pen. Air inside of the pen can not only cause print defects, it can also cause the pen to stop printing before all of the ink has been used. If the pen goes below the reservoir, ink will seep from the printhead, potentially damaging the system. This is reiterated on the back of the diamond-shaped reservoir packaging shown in Figure 8. Figure 8: Handling Cautions The reservoir and pen should always be held when handling the system. The system should never be held or carried around such that the pen or reservoir is dangling by the tubing. These actions could cause loss of ink containment. Storage If the printing system has a capping station, it is best to leave the pens in the printer even when the printer is not in use. If the printer does not have a capper, it is acceptable to leave the pens in the machine for a short period of time. The next time that the printer is used, the printhead will have to be cleaned as instructed (see printhead
maintenance section) in order to obtain optimum print quality. If the systems will not be used for long periods of time (more than two days), or if for some reason the print cartridges and reservoirs have to be taken out of the machine, the systems must be stored carefully. The pen must be stored above the reservoir in order to maintain the proper internal system pressure. The best way to keep the pressure regulated is to rubber band the system together with the pen resting on top of the ink reservoir as shown in Figure 9. The pen is resting on the flat surface of the reservoir. Figure 9: Storage of a Connected System It is very important to keep the printhead in an area that is relatively free of dust and paper particles and is not too dry. For long-term storage, the system can be placed in a Tupperware container with a damp sponge or towel to maintain humidity and prevent the pen from drying out. When the systems are ready to be used again the printhead will need to be cleaned in order to obtain acceptable print quality. Disposal When the ink system has reached the end of its life, it must be disposed of as a system because of the permanent pen to reservoir connection. There is nothing toxic within the system so it may be disposed of in normal garbage. What little ink is stranded in the system may leak out when it is placed in the garbage so it may be best to place the systems in plastic bags prior to disposal. An ink mess could also be avoided by kinking the tubing between the reservoir and the pen before it is placed in the trash. The tube can be kinked by bending the tubing and tying it in a knot. If there should be an ink spill, soap and water should clean up any problem areas. Lava soap also works well to get the ink off of hands. Printhead Care Inserting and Removing the Print Cartridge The print cartridge should stay in the carriage at all times except when the operator is replacing it, cleaning it, or storing it. When the cartridge is removed from the
carriage, it is important to hold the cartridge by the black side covers of the pen. Do not pull the cartridge out of its place by the tubing or the clip. The print cartridge should never be shaken or dropped. Shaking the print cartridge does not mix up the ink. It actually hurts the print quality because it allows little bubbles to form near the ink firing chambers. These bubbles prevent the nozzles from firing causing white streaks in print and images. Purging the Nozzles If the printhead sits inactive for a period of time, ink may dry in the nozzles. Address printing may not remove these ink plugs from the nozzles. White streaks will then show up in the printed text or graphic. In order to obtain better print quality, this ink plug needs to be forced out or purged. Some machines offer purging or servicing functions that may remove these ink plugs. If a machine does not have this capability, most ink plugs can be removed by printing a few addresses or graphics in a high resolution. The higher resolutions (600 dots per inch, for example) exercise more nozzles and push more ink out. This purging operation as well as wiping the printhead should be done after every extended period of down time in order to prevent unacceptable levels of print quality. Wiping One of the most critical paths to good print output is the maintenance of the printhead. During printing, ink can build up on the printhead causing black spray in the text. Paper fibers and dust can also build up on the printhead degrading the print quality. Proper printhead maintenance will allow the pen cartridge system to produce good print quality the whole life of the system. A cotton TexWipe and de-ionized water is one of the best ways to wipe ink and other build-up off of the printhead. A TexWipe is a 100% cotton, high-density cloth with no chemical additives. Something comparable is adequate to wipe the nozzles. For example, any soft cloth that doesn t leave fibers behind is acceptable. It is important to make sure that the cloth used does not have any small fibers that could be left behind to clog the nozzles. A sponge or toilet paper, for example, would both leave particles on the printhead. The cloth must also be soft so that it does not scratch the pen. Paper towels are not recommended because of their abrasiveness. De-ionized water is better than tap water because tap water contains an unmonitored amount of minerals. During wiping the water cleans out the nozzles and the firing chambers. The water mixes with the ink in the chambers. Over time, the minerals in tap water can leave behind deposits in the chambers that block it completely. A blocked chamber will show up as a white streak in text or graphics. The direction and force of the wipe is also important to note. During wiping, harmful particles on the top of the printhead can be wiped into the nozzles if not careful. It is important to wipe in the direction of the nozzles as shown in Figure 10. The printhead should be pointing down while it is being wiped. This position will prevent the nozzles from pulling little bubbles into the firing chambers.
Figure 10: Direction of Wiping A large pressure is not necessary to clean the particles off of the printhead. A large pressure can actually cause particles to scratch the printhead. Scratches can cause the nozzles to fire in improper directions adversely affecting print quality. It is very important to always be gentle when cleaning the printhead. It is also important to keep the electrical interconnects of the printhead clean. These pads can also be cleaned with a TexWipe and de-ionized water or even a Q-Tip. It is important to make sure that this section of the pen is dry before it is re-inserted into the printer to eliminate the chance of an electrical short. Trouble Shooting There are several things that can be done to recover damaged systems. The following list acts to troubleshoot any problems that may appear. Problem Action Air in tube The system will function properly with as much as 4 inches of visible air in the tube. Connect the system and use it to print. Pen will not print Check to make sure the tape is off of the printhead
Re-insert the pen into the carriage Install a new print cartridge White streaks in text or graphics Re-insert the pen into the carriage Wet wipe and purge the pen (There are clogged nozzles.) Clean the interconnects Black streaks around text Wet wipe the pen (There is ink buildup.) Ink is seeping from the nozzles Verify that the reservoir is below the pen (approximately 4 inches) Verify that the reservoir box is not being pinched The system isn t printing because the pen was held more than 10 inches above the reservoir. Hold the pen below the reservoir until ink starts to seep out of the nozzles. Once the ink is running freely, keep the pen above the reservoir. Wet wipe the pen to clean up any spilled ink. Text characters and graphics are light Verify that the reservoir is below the pen (approximately 4 inches) Replace printhead and reservoir