JPS6018358A - Magnetic printer - Google Patents

Abstract

PURPOSE:To almost perfectly remove a residual developer, by applying a charge to a developer remaining on a magnetic latent image carrier body, and thereafter, removing the residual developer from the magnetic latent image carrier body by electrostatic force. CONSTITUTION:The developer 12 remaining a magnetic latent image carrier body 1 after transfer receives the desired charge by discharge from a pre- cleaning corotron 8A arranged close to the feed path of the carrier body 1 and bias voltage is applied to the bias roll 13 arranged downstream from the pre- cleaning corotron 8A by a high voltage power source 14. An electrolytic field of the desired polarity and intensity is generated between the bias roll 13 and the opposed roll 15 arranged in opposed relation thereto. The residual developer 12 on the carrier body 1 is detached from the carrier body 1 by electrostatic force of the electrostatic field affecting the charge possessed by the residual developer 12 when passed between the bias roll 13 and the opposed roll 15 and adhered to the bias roll 13. By the above mentioned mechanism, the cleaning of the carrier body 1 is achieved.

Description

Detailed Description of the Invention (Field of Application) The present invention relates to a magnetic printer, and particularly to a magnetic printer equipped with a cleaning means that can effectively remove developer remaining on a magnetic latent image carrier. It is related to printers.

A magnetic printer forms a magnetic latent image on a magnetic latent image carrier,
An image developed using a magnetic developer is transferred onto plain paper or the like to obtain a hard copy, and has recently been attracting attention as a printer.

In this case, the magnetic latent image carrier is used repeatedly, and the developer remains on the magnetic latent image carrier even after the image is transferred, so the above-mentioned method is applied after the transfer and before the formation of the magnetic latent image. It is necessary to remove residual developer. For this purpose, a cleaning device is usually provided between the transfer section and the latent image forming section.

(Prior art) A typical technology that forms a latent image corresponding to the original image on a latent image carrier, visualizes it with a developer, and transfers this image onto plain paper, etc. to obtain a hard copy. There is xerography.

Cleaning devices for latent image carriers used in xerography include (1) vacuum fur brush, (2) vacuumless fur brush, (3) doctor blade, (4) wiper blade, and (5) web. Among the various cleaning devices mentioned above, vacuum cleaners are superior in terms of cleanability (residual developer removal ability), lifespan, and reliability, and have a track record of use. It's a fur brush.

In addition, with xerography, even after cleaning with a vacuum fur brush, the density is 0.015 by visual measurement.
Usually, a certain amount of developer remains on the latent image carrier.

In xerography, even if such a small amount of developer remains on the latent image carrier, it does not interfere with the formation of a latent image in the subsequent process.

This is because latent image formation in xerography is performed by inputting imagewise light, so a layer of several tens of μm thick is formed on the latent image carrier (photoreceptor).
This is because even if the developer having the size of 0.015 is scattered at a density of about 0.015, the photoreceptor is exposed to light as desired.

FIG. 1 is a schematic diagram of a general magnetic printer.

The magnetic latent image carrier 1 has a magnet 7 for both unidirectional magnetization and demagnetization.
The magnet is uniformly magnetized in one direction. The magnetic latent image carrier 1 is, for example, a tape in which CrO'z powder is coated as a magnetic layer on a Mylar base having a thickness of 75 μm.

The magnetic latent image carrier 1 is heated pixel by pixel according to an image signal by a thermal head 10 that is in sliding contact with the magnetic latent image carrier 1. At the same time, a bias magnetic field in the opposite direction to the unidirectional magnetization is applied to the heated portion by the bias magnetic field generating magnet 11.

As a result, a magnetic latent image corresponding to the image signal is formed on the magnetic latent image carrier 1 due to the thermal residual magnetization phenomenon. The magnetic latent image formed in this manner is processed by a developing device 2 using a magnetic developer (e.g., -component non-conductive magnetic toner;
It is visualized with a specific resistance of 1010 Ωcm).

The visualized developer is given, for example, a negative charge by the pre-transfer corotron 3.

When the magnetic latent image carrier 1 reaches below the transfer roll 4,
The plain paper 6 fed from the paper tray 5 joins together, and the magnetic latent image carrier 1 and the plain paper 6 advance at a constant speed.

Since a bias voltage is applied to the transfer roll 4 to attract the charge of the developer, the developer on the magnetic latent image carrier 1 is transferred onto the plain paper 6 by the transfer roll 4 . The plain paper 6 to which the developer has been transferred then passes through a fixing device (not shown) and becomes a hard copy.

On the other hand, the magnetic latent image carrier 1 that has completed the transfer is demagnetized by the magnet 7 for unidirectional magnetization and demagnetization, and is uniformly magnetized. The developer remaining on the magnetic latent image carrier 1 after the transfer is neutralized by a pre-clean corotron 8, and then removed by an appropriate cleaning device @9.

By repeating the above process, various hard copies can be obtained.

The present inventors installed the vacuum fur brush described above in a magnetic printer having the configuration shown in FIG. 1, and evaluated the printer as a cleaning device.

Note that this platform (1) has a thickness of 5 μnl as the magnetic layer of the magnetic latent image carrier 1;
When using Cr 02 E, its coercive force 1-I C is about 500 oersted, and the Curie point TO is 126°C.
(2) As the magnet 7 for both unidirectional magnetization and demagnetization, a magnet capable of generating a magnetic field of about 700 oersteds is used in the magnetic layer (CrOz) portion of the magnetic latent image carrier 1, (3 ) As the thermal head 10, one is used that can raise the temperature of the heating element itself to 350°C and the temperature of the magnetic layer of the magnetic latent image carrier 1 to nearly 200°C (more than the Curie point TO); (4.) As the bias magnetic field generating magnet 11, a magnet capable of generating a magnetic field of about 50 degrees in the magnetic layer of the magnetic latent image carrier 1 was used.

In a magnetic printer with this configuration, the residual developer after cleaning with a vacuum fur brush was determined to be 0 according to visual density measurement using the same method as the xerography described above.
．． It was about 002.

Although this value is better than the value in normal xerography, in a magnetic printer, the thermal head 10, which is a means for forming a latent image corresponding to an image, is pressed against the magnetic latent image carrier 1 and Because of the dynamic contact, residual developer adheres to and accumulates on the heating element of the thermal head.

Then, due to the influence of the accumulated developer, the heat of the heating element of the thermal head is not sufficiently transmitted to the magnetic latent image carrier 1.

For this reason, the thermal residual magnetization phenomenon of the magnetic latent image carrier 1 does not occur as designed, which causes a problem in the formation of a magnetic latent image.

As a result of repeating the copying process of forming a latent image → developing → transferring → demagnetizing → cleaning with the magnetic printer configured as shown in FIG. It was confirmed that there was a problem with image formation.

As mentioned above, the cleaning means in the conventional magnetic printer mechanically wipes off the residual developer on the latent image carrier, and therefore has the following drawbacks.

(1) If the contact state of the cleaning brush or the like with the 7VI image carrier is not good, the ability to remove residual developer (cleanability) will be reduced. Therefore, adjustment of the contact state is delicate and maintenance adjustment is difficult.

(2) The lifespan of cleaning brushes and the like that come into direct contact with the latent image carrier (the lifespan is short due to mechanical contact) is directly related to the lifespan of the cleaning means as a whole, resulting in a lack of long-term reliability.

(Objective) The present invention has been made to eliminate the above-mentioned drawbacks, and its object is to provide a magnetic printer that can remove almost 100% of the residual developer on the magnetic latent image carrier after transfer. Our goal is to provide the following.

(Summary) In order to achieve the above object, the present invention applies an electric charge to the developer remaining on the magnetic latent image carrier after transfer, and then transfers the remaining developer to the magnetic latent image carrier by electrostatic force. It is distinctive in that it is structured in such a way that it can be removed from the sea urchin.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic side view showing the main structure of an embodiment of the present invention. In the figures, the same reference numerals as in FIG. 1 represent the same or equivalent parts.

Developer 12 remaining on the magnetic latent image carrier 1 after transfer
is given a desired charge (polarity and charge amount) by discharge from a pre-clean corotron 8A disposed close to the travel path of the magnetic latent image carrier 1.

A bias voltage is applied by a high voltage power supply 14 to a bias roll 13 disposed downstream of the pre-clean corotron 8A. On the other hand, a counter roll 15, which is disposed opposite to the bias roll 13 with the magnetic latent image carrier 1 in between, is grounded.

Therefore, the bias roll 13 and the opposing roll 15
An electrostatic field of desired polarity and magnitude can be generated between the two.

The residual developer 12 on the magnetic latent image carrier 1, which has been given a certain polarity (for example, negative) and a certain basic charge by the pre-clean corotron 8A, is transferred to the bias roll 13.
When the residual developer 1 passes between the bias roll 13 and the facing roll 15, an electrostatic field (for example, positive on the bias roll 13 side) generated between the bias roll 13 and the facing roll 15 causes the residual developer 1 to
Due to the electrostatic force exerted on the charge of the latent magnetic image carrier 1 , the latent magnetic image carrier 1 is detached from the magnetic latent image carrier 1 and attached to the bias roll 13 .

In this way, cleaning of the magnetic latent image carrier 1 is accomplished.

Bias roll 13. The developer attached to the bias roll 13 is lightly pressed against the bias roll 13, and is removed by the developer removal means (blade-shaped magnet) 16 in contact with the bias roll 13.
Departed from and collected. As a result, bias roll 1
The developer no longer accumulates on the surface of the bias roll 13, and the bias roll 13 can be kept clean for a long time.

In addition, when the blade-shaped magnet 16 is used as the developer removal means from the bias roll 13, by appropriately setting the magnetization size and polarity, as well as the arrangement position, (1) the blade-shaped magnet 16 (2) The magnetic field generated from the magnetic latent image carrier 1 can be prevented from having any influence on the magnetization state of the magnetic layer of the magnetic latent image carrier 1, or (2) it can be made to have a large influence, for example, on the magnetic latent image. It is also possible to make it possible to have both erase and unidirectional magnetization functions.

In the latter case, as is clear, the unidirectional magnetization/demagnetization magnet 7 can be omitted or simplified.

FIG. 3 is a schematic side view showing the main structure of a second embodiment of the present invention. In this figure, the same reference numerals as in FIG. 2 represent the same or equivalent parts.

As is clear from the comparison with FIG.
9, the residual developer can be removed without adhering to the bias roll 13, improving maintainability.

As can be easily seen from this figure, in operation, the web 19
is pulled out from the feed roll 17 and taken up by the take-up roll 18
It is wound up.

Therefore, when the developer remaining on the magnetic latent image carrier 1 is attracted toward the bias roll 13 by the electrostatic field generated between the bias roll 13 and the opposing roll 15, the residual development occurs. The agent will adhere to the tab 19 without adhering to the bias roll 13. and,
The web 19 is collected as it is on the take-up roll 18.

In this way, in this embodiment, the bias roll 13 is completely prevented from becoming dirty, and the new surface of the web 19 is always interposed between the bias roll 13 and the magnetic latent image carrier 1. , the residual developer removal effect can always be achieved as designed without deterioration of the residual developer removal effect.

In this embodiment, the web 19 also has cleaning capabilities as a wipe-type web cleaner in normal xerography. That is, according to this embodiment, the dual cleaning function enables more complete removal of residual developer.

FIG. 4 is a schematic diagram of a magnetic printer used in experiments by the present inventors. In this figure, the same reference numerals as in FIGS. 1 and 3 represent the same or equivalent parts.

As is clear from the comparison with FIGS. 1 and 3, this configuration corresponds to the conventional magnetic printer shown in FIG. 1 to which the residual developer removing means shown in FIG. 3 is added.

As the counter roll 15, a metal roll (60nunφ, ground potential) is used, and as the bias roll 13, a 6-resistance rubber roll (30n+mφ, resistance value of about 100Ω, hard fM
50'), and the distance between both rolls was such that the nip width was about 4 mm.

As the magnetic latent image carrier 1, a Mylar base having a thickness of 75 μm and a Cr 02 magnetic layer coated to a thickness of 10 μm was used. As the web 19, the same web used in a 220o type electronic copying machine manufactured by Fuji Xerox was used.

As the pre-clean corotron 8A, we used a developer (-component non-conductive magnetic toner, specific resistance 10Ω-am) that can make the toner specific charge about +15 μC/(+), and a metal shaft that is the axis of the bias roll 13. (1
0 mmφ), a voltage of minus 1 was applied.

Then, as a result of repeating the above-described copying process of latent image formation, development, transfer, demagnetization, and cleaning, an extremely good copy was obtained on the plain paper 6.

In addition, the disadvantages seen in the conventional example, such as the heating element of the thermal head 10 being contaminated by the developer and causing problems in forming a magnetic latent image, did not occur.

As a result of experiments, it was confirmed that good copies could be obtained even after repeating copy wrestling 100,000 times.

Also, from the equipment shown in Figure 4, the Preclean Corotron 8
It was also confirmed that the copying process proceeded satisfactorily even when the vacuum fur brush 9 was omitted and the cleaner was formed using only the residual developer removing means shown in FIG.

In this case as well, it was confirmed that good copies could be obtained even after repeating the copying process 100,000 times.

(Modification) The present invention can be modified and implemented as follows.

(1) The opposing rolls do not need to be rolls, and may be simply opposing flat plates or pressure plates.

(2) The cleaning means may be placed at any position as long as it is between the transfer means and the thermal head.

(Effects) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) The cleaning means is based on electrostatic force,
Since the cleaning force (electrostatic force) acts on all the residual developer, the cleanability is greatly improved and almost 100% cleaning is possible.

(2) Since no mechanical contact is involved, there is a high degree of tolerance for relative position adjustment such as the contact pressure between the cleaning means and the magnetic latent image carrier or the nip width between the bias roll and opposing rolls. This simplifies maintenance and adjustment.

(3) The life of the cleaning means is extended, and the long-term reliability of the magnetic printer as a whole is also increased.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the schematic configuration of a conventional magnetic printer;
FIG. 2 is a side view of essential parts of an embodiment of the present invention, FIG. 3 is a side view of essential parts of a second embodiment of the invention, and FIG. 4 is a side view showing a schematic configuration of an embodiment of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1... Magnetic latent image carrier, 2... Developing device, 3... Pre-transfer corotron, 4... Transfer roll, 5
... Paper tray, 6 ... Plain paper, 7 ... One-way magnetization and degaussing magnet, 8,8A ... Pre-clean corotron, 9 ... Cleaning means, 1° ...
・Thermal head, 11...Magnetic latent image carrier, 12.
...Residual developer, 13...Bias roll, 14...
・High voltage power supply, 15... Opposing roll, 1... Web agent patent attorney Michito Hiraki and 1 other person

Claims (5)

[Claims] (1) a magnetic latent image carrier that travels in one direction along a scheduled route; a magnet device that is arranged along the scheduled route and uniformly magnetizes the magnetic latent image carrier in the scheduled direction; a thermal head device that heats a latent image carrier pixel by pixel according to an image signal and forms a magnetic latent image on the magnetic latent image carrier by a thermal residual magnetization phenomenon; and a thermal head device that applies a developer to the magnetic latent image. a developing device for making the magnetic latent image visible, a means for transferring the visualized developer image onto plain paper, and a developing device disposed between the thermal head device and the image transfer means, A magnetic printer comprising a cleaning means for removing residual developer on an image bearing member, the cleaning means comprising means for charging the residual developer with an electric charge of a predetermined polarity, and a magnetic printer provided downstream of the charging means. a high-voltage power source that applies a voltage to the bias roll arranged and applies an electrostatic force to the residual developer on the magnetic latent image carrier passing under the bias roll, thereby causing the residual developer to be attracted to the bias roll; A magnetic printer characterized by: (2) A patent characterized in that it further includes means for removing residual developer attached to the bias roll. (3) The magnetic printer according to claim 2, wherein the means for removing residual developer attached to the bias roll is a blade-shaped magnet. (4) A magnetic printer according to claim 3, characterized in that the blade-shaped magnet also uses a magnet device for uniform magnetization. (5) a magnetic latent image carrier that travels in one direction along a predetermined route; a magnet device that is arranged along the predetermined route and uniformly magnetizes the magnetic latent image carrier in the predetermined direction; a thermal head device that heats a latent image carrier pixel by pixel according to an image signal and forms a magnetic latent image on the magnetic latent image carrier by a thermal residual magnetization phenomenon; and a thermal head device that applies a developer to the magnetic latent image. a developing device for making the magnetic latent image visible, a means for transferring the visualized developer image onto plain paper, and a developing device disposed between the thermal head device and the image transfer means, A magnetic printer comprising a cleaning means for removing residual developer on an image bearing member, the cleaning means comprising means for charging the residual developer with an electric charge of a predetermined polarity, and a magnetic printer provided downstream of the charging means. A bias roll arranged, a TC web movably arranged between the bias roll and the magnetic latent image carrier, and a voltage applied to the bias roll to remove the residue on the magnetic latent image carrier passing under the TC web. A magnetic printer comprising: a high-voltage power source that applies electrostatic force to the developer and causes it to be attracted to the two nibs.