Laser printer drum assembly recycling and maintenance

The laser printer is a computer output device that was developed in 1980 and integrates optical technology, electronic technology, and mechanical technology into an integrated, highly automated computer. Although there are many kinds of laser printers, either black and white or color are composed of a laser scanning system, a toner cartridge mainly composed of toner and a photosensitive drum, and a circuit portion.

First, the working principle

The working principle of most laser printers can be divided into six steps:

Drum charging process

At the beginning of printing, the photosensitive drum is uniformly charged negatively on the outer surface of the drum. The primary corona discharge electrode is mounted in a long, narrow slot. High voltage is used to apply a high voltage to the primary corona discharge electrode. This causes the corona release electrode to have a high voltage of 6000 V. The high pressure then causes the surrounding air to become mobile. Electron ions. Underneath the primary corona discharge electrode is a grid. The grid is usually charged with a voltage of -600 V. It can attract the ions in the air surrounding the discharge electrode of the corona and move the negatively charged ions to the surface of the photosensitive drum. When moving, it limits the voltage of the negative ions so that the surface of the drum is evenly charged with a -600V charge layer.

2. The exposure process

After the charging process is completed, the laser generator generates a laser beam, which is reflected by the scanning mirror onto the photosensitive drum, so that the photosensitive layer of the irradiated part (word or image) becomes a conductor, and the -600 V charge on the surface is transferred to the ground. The bleed-off becomes a low pressure of approximately -100V. At this time, a dot with a voltage of -100V is written on the surface of the photosensitive drum, that is, an electrostatic latent image dot of an invisible text or image. The exposed drum surface still retains -600V of charge.

3. Development (on toner) process

The development is mainly focused on the photosensitive electrostatic latent image on the photoconductive drum to obtain visible text or image points. During the rotation of the photosensitive drum, after the latent image point meets the toner on the developing roller (drum), the high-voltage toner is adsorbed by the latent image point of the photosensitive drum at a lower voltage. At this time, the photosensitive drum is -100V latent image point becomes visible text or image.

4. The transfer process

While the developed photosensitive drum continues to rotate, when the surface of the photosensitive drum passes through the transfer corona, the developed character or image toner is transferred onto the printing paper. Because of the positive charge on the back of the paper, the text or image point of the negatively charged toner on the photosensitive drum is tightly absorbed on the paper. At the same time, a negative charge is also generated on the static eliminator to eliminate the attraction between the photosensitive drum and the printing paper, so that the printing paper can be easily separated from the photosensitive drum without being adsorbed.

5. The fixing process

After the text or image is transferred to the printing paper, it is further cured by the fuser (warming). When the printing paper passes through the fuser, the high temperature in the fuser melts the toner at 180°C to 220°C, and the pressure between the two rolls then forces the melted toner into the fibers of the paper to fix the text or image.

6. Preparation process

In the transfer process, when the toner is transferred onto the printing paper from the surface of the photosensitive drum, the surface of the photosensitive drum will always have some residual toner, and the rubber scraper on the photosensitive drum will collect the residual powder into waste. The silo keeps the photoreceptor drum clean. The photoconductor drum passes through the charging process after one rotation cycle and starts the next cycle.

Second, drum assembly (toner box)

Use regeneration technology to increase the utilization of the drum assembly (toner cartridge). While reducing the printing cost, without changing the performance of the drum assembly, it is necessary to understand the wear characteristics of the various components and the relationship between them and the interaction between them, so as to make correct judgments according to the printed products or fault phenomena.

A recycling drum assembly (toner cartridge) costs less than 1/4 of the original product, and has a longer life, allowing 3-5 times powder filling, which further saves printing costs. The economic benefits of the drum assembly (toner cartridge) are substantial, and the proper performance of the drum assembly (toner cartridge) is normal. The following breakdown of the drum assembly (toner cartridge) is as follows:

Photoconductor drum

The photosensitive drum is an original part of the drum assembly (toner cartridge); the charging, exposure, development, transfer, fixing, and preparation processes of the laser printer all work around the photosensitive drum; the photosensitive drum is also consumed by the laser printer. Material, a photosensitive drum whose service life is generally around 6000-10000 sheets, is a consumable material for the drum assembly (toner cartridge) integrated with the toner, (but some toner cartridges can be filled with ink The price of a new drum kit (toner cartridge) is about 1/10 of that of the whole machine. If it is in the frequent printing of sulfuric acid paper and printing paper samples, replace the drum kit (toner cartridge) for 3-6 months. The amount of money may reach or exceed the price of a complete machine.

Some laser printers adopt an integrated design of photoreceptor drums and toners to replace photosensitive drums and toners; if properly maintained and used, a drum kit (toner cartridge) can be replaced with a drum or powder 3-5 times. .

In the recycling drum assembly, the key components to be considered include: a photosensitive drum, a cleaning blade, a developing roller, and a primary charging roller. These components work together in the drum assembly, producing good print results and improper handling. It also affects the cycle of use.

There are three main types of photoconductor drum wear:

1 partial defect. It means that there is a defect in the black conductive layer outside the aluminum drum of the photosensitive drum, resulting in that the photosensitive drum cannot be used anymore.

2 full wear. It means that the photosensitive layer of the photosensitive drum is "aged" and can be used until the surface of the photosensitive drum cannot be charged and the printed product appears as a bottom ash.

3 groove wear. It refers to the photosensitive drum has "scratched" to form a groove or groove, there are many reasons.

In order to reduce the wear of the photosensitive drum, a layer of toner and talc powder may be spread on the photosensitive drum before the new photosensitive drum is used or after cleaning the photosensitive drum. When a new original drum assembly (toner cartridge) is opened, It can be noticed that it uses a liquid lubricant, and the wear rate of the photosensitive drum after use of the lubricant film has been reduced by about 30%.

In order to reduce the unnecessary wear of the photosensitive drum and prolong its service life, the following issues must be noted:

1 The photoreceptor drum is a silicone photoconductor, and working on the drum for a long time has fatigue problems. In the work, the author recommends that the conditional unit use two drum assemblies (toner cartridges) interchangeably, and the cross-use time is preferably one week.

2 When printing about 6000-10000 sheets, it was found that the text and image of the printed product were light in color and uneven in depth. After excluding the transfer electrode, toner, etc., the service life of the photosensitive drum was terminated and it should be replaced.

(3) Replacing the photoreceptor drums The photoreceptor drum surface can be easily treated with the photoreceptor drum surface with no damage to the drum surface. The method is to use 3-5g of chromium oxide, directly with the absorbent cotton rubbed with chromium oxide in the direction of the drum shaft light and uniform, and wipe it all over again.

4 Pay attention to the consumption of toner and the number of prints in the drum kit (toner cartridge). When the toner is low or there is no toner, it is very disadvantageous for the drum.

5 In order to avoid rough paper damage to the drum, it is best to use offset paper within 70g-120g for printing paper, because the offset paper adds a coating layer to the paper surface to fill the uneven surface of the paper. The paper to be used is preferably sealed with kraft paper or placed in a plastic bag, and cannot be scattered to prevent the paper from getting damp.

6 To prevent toner, toner, and paper dust from damaging the photoconductor drum, when the toner cartridge in the drum assembly is filled with new toner, the remaining toner, granules, and paper scraps in the toner supply container must be blown out. .

2. Drum (development roller)

The drum is located above the supply silo. The center of the drum is a fixed permanent magnet. The outside of the fixed magnet is a rotating metal sleeve. There are four magnetic poles N1, N2, S1, and S2 on the upper and lower sides of the magnet. The four magnetic poles have different Magnetic strength. The N2 and S2 poles are responsible for toner handling. N1 is responsible for stacking toners. S1 is responsible for developing jobs. The roller sleeves have DC high voltage and AC high voltage. When the drum is working, the friction between toner ions and the surface of the roller cover is negatively charged with the friction of other toner particles. At the moment of the negative half cycle of the AC, the toner particles are repelled at the developing pole S1 from the roller sleeve. It was pushed to the photoconductor drum. The latent image area on the photoconductor drum has enough attraction force for the toner particles and the toner does not return to the roller sleeve to complete the development process.

The solution to the problem with the drum is as follows:

1 Reduced print density. It is mainly the aging of the black conductive layer on the metal sleeve outside the drum. When using the drum assembly (toner cartridge), increase the print density (as with the original product) and replace the dampened black roller cover.

2 Ink concentration decreases. The black conductive layer of the Canon LBP-BX printer's developer roller is worn faster because the toner cartridge contains a charging blade. Its function is to control the amount of toner on the drum surface and increase the ink by increasing friction. The amount of powder charge. However, the friction of the charging sheet accelerates the wear of the black conductive layer of the drum, so that the refilled toner cartridge is significantly reduced in print darkness. In order to ensure the printing effect, the magnetic roller sleeve is replaced or the black conductive layer is applied to overcome the problem. The above drawbacks, the second is to replace the new drum, do not try to imitate.

3. Cleaning blade

The cleaning blade is made of rubber. Soft, transparent book. Its role is to scrape off the remaining toner on the drum, so that the photosensitive drum surface maintains a uniform -100v charge. At work, how to identify the quality of the cleaning blade is summarized as follows:

1 After the cleaning blade has been used for a long time, the color of the blade becomes amber, and it becomes hard and brittle. Replace with a new blade to avoid scratching the photosensitive drum due to hardness.

2 The cleaning blade must be replaced with a new one due to aging.

4. Charging roller

The charging roller consists of a metal shaft, a conductive foam rubber layer, a resistive layer, and a protective layer. The conductive rubber layer not only provides the charging circuit but also the pressure of the charging roller on the drum surface. The role of the resistive layer is to limit the charging current from the charging roller to the drum. The role of the charging roller is to erase the electronic characters and images left on the photoreceptor drum, and charge the surface of the drum with -100 volts. During operation, DC high voltage and AC high voltage are applied between the charging roller and the photosensitive drum, and the two represent superposition. At the peak of the exchange, the charge roller transfers the charge to the photosensitive drum to form a ribbon charging area. The density of the distribution of the ribbon charging area on the photosensitive drum depends on the frequency of the alternating current. In other words, the higher the printing speed, the higher the required frequency of AC voltage.

In the regeneration drum assembly (toner cartridge), the charging roller is one of the important components, and it is also a relatively sensitive component. The following breakdown of the charging roller is summarized as follows:

1 The print has light grey bottom ash and ghosts. The main reasons are: A. The protective layer of the charging roller is damaged, which affects its moisture-proof, chemical-proof and other properties, resulting in a decrease in the charging effect; B. Conductive layer, resistive layer, and protective layer of the charging roller conductive Poor performance; C. Market to buy rough, uneven charging roller and sticky charge roller surface accumulation toner particles, paper dust, etc. to reduce the charging effect; D. fuser roller contamination; E. If the fuser roller produces ghosting The failure occurred during the image formation due to the charge roller or photoconductor drum.

2 The vertical direction and repeated black spots appear on the prints: A. The charging roller has small pits. After the toner is trapped and filled with small pits, it is contaminated on the photosensitive drum. B. If the charging roller is intact, it can be taken from the drum. , Fusing roller and other aspects of inspection.

3 Printing produces horizontal black lines: The replaced charging roller does not have a patented resistance layer, and the DC current is relatively large, and horizontal black lines are prone to occur, causing damage to the photosensitive drum.