JPH09230667A - Method for forming toner image using two sorts of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a two-color toner image with a high resolution without risk of displacement to be caused by toner separation. SOLUTION: A toner image forming method according to the invention includes the first image formation using a discharge region development (DAD) and the second image formation using a electrostatic charged region development (CAD), whereby a two-color toner image is formed from two types of toners of the same color. If the second toner image exposes a photoconductive member in terms of imaging through a transparent bottom part, the resolution and sharpness of the first toner image are improved. Displacement, etc., caused by exfoliation of the first toner image in association with the development of the second image can be improved by using a rotary magnetic core as a developing solution containing a hard type magnetic carrier is moved in a soft brush 11 through contacting of the development zone with the electrostatic image.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the formation of toner images, and more particularly to the formation of images of two different types of toner, for example two different color toners.

[0002]

2. Prior Art and Problems to be Solved by the Invention 1
U.S. Pat. No. 5,001,028, issued March 19, 991 to Moshaua et al., Provides a multicolor toner by forming two unfixed images on one frame of a photoconductive image member. It is representative of many patents relating to image formation. Color printers according to this general method that use charged emission area development (DAD) and electronic exposure for each image are commercially available.

In the Moshauer patent, the second and subsequent images are toner developed by a special toner development process that uses a carrier with high coercivity and a rotating magnetic core. This process provides a very soft magnetic brush that is less likely to damage the previous toner image when compared to a conventional magnetic brush, even if the brush's brush touches the image member.

The "transfer by peeling" of a first image to a second station is frequently described in various documents, especially in repeated DAD tone development steps (DAD-DAD imaging). Many past references are DAD-D
It suggests a projection toner application method for applying toner for the second and second and subsequent images in the AD process. Using this method, the "peeling transfer" of the first image to the second toner application station is reduced, but at the same time the speed at which the second image is brought to correct and full density is reduced. U.S. Pat. No. 5,409,791, Kokeyenen et al., Issued April 25, 1995, is similar to the process described in the Moshouer reference, but uses brush brushes that are not in contact with the imaging member. It has been demonstrated that the toner application process used can reduce the release-induced migration of projected toner while applying toner at a higher rate (although not as fast as Moshauer contact toner application).

The use of projection toner application can significantly reduce stripping migration, and the use of the Koeinen invention can improve density even with faster toner application than conventional projection systems. However, the performance of projection toner application is greatly influenced by whether the gap between the toner application device and the image member is accurate. We know that it is very difficult to maintain this gap accurately during actual work, and in fact, to do so, the parts themselves must be more complex and more expensive. .

European Patent Application 94-107.101.1 (0625 73) dated November 23, 1994.
No. 0), the toner on the edge of the area of the first image in contact with the second image tends to move to the second image during the second exposure, the DAD-DAD system. About the problem. By superimposing the first image on the second image, this problem of this process can be solved. By exposing the second image from the base, the images can be easily overlaid.

Several references propose the combined use of charge area development and charge area development (DAD and CAD). For example, it discloses a method in which a first image is formed by DAD, and an image member is recharged and re-exposed by a second image formed by CAD, September 1991.
See Tab. US Pat. No. 5,045,893 dated March 3. Also in this regard, US Pat.
208,636, 5,241,356, 5,0
See also 49,949 and 5,258,820.

One object of the present invention is to improve upon the prior art multiplex image system described above.

[0009]

The above and other objects can be achieved by a method of exposing and exposing an image member to a first polarity to form an electrostatic image. The electrostatic image is similarly developed (DAD) with toner charged to the first polarity. The image member, preferably not recharged, is still exposed to form a second electrostatic image having the first polarity.
This image is coated with toner of a second polarity, opposite the first polarity (CAD). Preferably, the second toner application step uses contact development with a magnetic brush of Moshauer type. That is, in this method, a "hard" magnetic carrier and a rapidly rotating magnetic core are used to bring the moving developer solution into direct contact with the image member during the development process. Because of contact development, the gap between the toner applicator and the image member is no longer a significant issue and improves image density when toner is applied at high speed. Compared to the DAD-DAD process, the migration due to toner peeling is much less. This is because the developing electric field of the second station 2 is maintained at a level that repels the toner of the first polarity. Also, due to the developing electric field, over-application of toner to the first image by the second station will rarely occur.

As a result of conducting an experiment using this process,
It has been found that the resolution of the image with lines tends to decrease. As a result of an analysis, this phenomenon was already disclosed in the patent application of Goose et al.
5 730), which is somewhat similar to the migration of toner during the DAD-DAD process described above, but also due to migration of toner during the second exposure step. The inventor has demonstrated that this problem can be solved by making a second exposure from the side of the image member opposite the side containing the first toner image. Therefore, the charge on the image member carrying the first image can be reduced to the charge level of the untoned portions of both images. It should be noted that this charge release is not the case for a superposed toner image as disclosed in the Guth application. This is because the image portion of the second image is completely separated from the first toner image. this is,
A solution based on reliable and complete charge release of the area under the first toner image in the second exposure.

Therefore, according to the preferred embodiment, "hard".
DAD-DA using contact development of a second image with a second exposure from the side of the image member opposite the side of the first toner image by a brush having a magnetic carrier and a rotating core.
The D process is used to form a high resolution two color toner image with no toner delamination migration.

[0012]

1-7 are seven step diagrams of a method for forming a two-color image; FIGS. 8-14 are sub-methods of the method of FIGS. 1-7; 15-FIG. 18 corresponds to FIG.
Another sub-method of four steps, different from the sub-method of FIG. 14; FIG. 19 is a schematic side view of the image forming apparatus; and FIG. 20 is a schematic side view of the developing station.

FIGS. 1-7 illustrate the formation of a two color toner image (sometimes referred to as the "secondary method") D.
This is the AD-CAD method. Referring to FIG. 1, the image member 1 includes an image surface 2 and an opposing or bottom surface 4. The image member 1 is preferably transparent. For example, polyester or other suitable transparent support belts or webs well known in the art and commonly used can be used. The image member has an image surface 2 coated with a suitable photoconductive layer to render the image member 1 photoconductive.
Includes a transparent conductive layer on top. The conductive layer and the photoconductive layer are
Very thin, not shown in the drawing. As an image member,
A glass drum on which a similar layer is applied can also be used.

The method of the present invention will be described using a negatively charged imaging member. It will be apparent to those skilled in the art that positively charged image members can be used as well.

The image member is uniformly charged to a negative potential.
The image member is image-wise exposed to form a negative electrostatic image and, as shown in FIG. 1, in the presence of an electric field that promotes the deposition of negatively charged toner according to the charge release of the electrostatic image. Then, the negatively charged toner is applied. That is, the toner shown in FIG. 1 adheres to the area of the lowest potential in the first electrostatic image and forms the first image formed by the DAD process, as shown in FIG.

As shown in FIG. 3, the image member is exposed from its bottom side 4 (preferably without recharging) to form a second electrostatic image. It is important that this exposure be done from the bottom side in order to discharge the charge below the first toner image, which is lower than the charge in the exposed areas surrounding the first toner image. If this charge cannot be discharged, then the negatively charged first toner will be forced by the charge into a region of the same or greater amount of charge adjacent to it, which causes The sharpness and resolution of one toner image are reduced. By exposing from the bottom side, the charge under the first toner image could be 50-100 volts lower than the charge in the area around the similarly exposed image. By doing so, the adjacent negative charge can hold the negatively charged toner of the first image in place.

Referring to FIG. 4, the second electrostatic image is tonered by a CAD toner application process. More specifically, the magnetic brush 11 containing positively charged toner applies toner to the image member 1 where there is an electric field that promotes toner adhesion on the high potential portions of the second electrostatic image. . Normally, in the case of CAD development, the electric field is biased, so in order to prevent the non-image part in the second electrostatic image from being developed, the magnetic brush 11 is The negative potential is slightly higher than the exposed part of the electrostatic image. The bias also prevents the negatively charged toner from being removed from the first image.

The two color toner image shown in FIG. 4 contains both negatively charged toner and positively charged toner. Image processing is performed so as to respond more evenly in the electric field to the movement of static electricity. This process is performed by a negatively biased corona charger 15, which sprays a negative charge onto the image surface of the image member 1, as shown in FIG. As is well known to those skilled in the art, a transparent image member 1 can be used to assist the operation of the charger 15 by an erase lamp 17 which can be placed on the opposite side of the image member 1, i.e. on the bottom surface. As shown in FIGS. 6 and 7,
The two-color image is transferred to the transfer promoting member or the roller 23 by the potential source 19
Is transferred to the image print sheet 30 in the presence of an electric field created by a bias and supplied by As shown in FIG. 7, the image print sheet 30 is separated from the image member 1 along with the printed bicolor image.

The use of CAD development with opposite polarity toner for the second image greatly reduces the tendency of the first toner to migrate to the second station due to delamination.
Or, the overcoating of the first toner image with the second toner is greatly reduced. Therefore, contact development can be used instead of projection development, an image with high density can be obtained at high speed, and the influence of the gap can be greatly reduced.

By using a brush similar to the brush of the Moshouer patent, the transfer due to toner delamination can be optimized. See Figure 2 for this brush.
It will be described in more detail at 0. This brush has a very soft brush that reduces the peeling effect of the first image of the brush and provides fast and very dense development at a relatively small development station.

The first resolution problem encountered was that caused by the toner in the first image migrating by peeling during the second exposure step. This toner migration is due to the negative polarity residual charge underneath the first toner, which pushes the toner onto the background of the second image with a lower residual charge after the second exposure. This problem has been virtually solved by exposing a second image from the bottom, as shown in FIG. 3 and as already explained.

Toner from the first image, which tends to migrate by peeling to the second toner station, tends to adhere to the background of subsequent images if the toner continues to carry the original charge. is there. The life of the developing device in the second station is determined by the extent of this toner movement. When a noticeable amount of the first negatively charged toner from the first image appears in the background of the second image, the second station developer must be replaced. Since the toner of the DAD-CAD process has the polarity shown in FIGS. 1 to 7, and as shown in FIG.
Since the developing brush is soft, this effect is very small, and the life of the developing device is relatively long. However, it has been found that the use of two sub-methods to increase the life of the second developing device further extends its life.

The first sub-method is shown in FIGS.
These figures show how if only the second color image is needed. That is, in the process of FIGS. 1-7, if the first toner image color is black and the second toner image color is red, the same device will occasionally redeem once or more times. In some cases, it may be necessary to form just an image. In the case of FIG. 8, when entering this process, the image member 1 has no charge. As shown in FIG. 9, the same charging device 9 used to form the first electrostatic image of FIG. 1 charges the image member 1 to a negative polarity. As shown in FIG. 10, the image member 1 is image-wise exposed to form a negative electrostatic image, and the electrostatic image is coated with positively charged toner from the magnetic brush 11, as shown in FIG. To be done.

The magnetic brush 11 has processed many images to date without changing the developer and contains some negatively charged toner from the first black image during the preceding two-color imaging process. . Some of the above negatively charged black toner particles tend to adhere to the background portion of the electrostatic image, as shown in FIG.

However, only the red image is needed in FIGS.
4, the processing step shown in FIG. 5 is not used and a red image with some black toner particles adhering to its background is transferred to the transfer station as shown in FIG. Sent. However, in the case of FIG. 12, the transfer electric field of FIG. 12 is opposite to the transfer electric field of FIG. 6 in order to facilitate the transfer of untreated positively charged (red) toner particles, while: The transfer of negatively charged (black) toner particles is prevented. Therefore, as shown in FIG. 13, the printing sheet 30 is separated from the image member 1 with the image of the red toner transferred to itself and the black toner transferred to the image member 1. As shown in FIG. 14, at the cleaning station, the image member 1 can be reused.
The cleaning device 29 removes the black toner from the image member 1.

The sub-method of FIGS. 8-14 provides a backgroundless copy with an old developer while actually removing some of the dirt on the magnetic brush 11. This type of extended monochromatic process cleans the second developer station, thereby extending the life of the developer.

FIGS. 15-18 show the steps of FIG. 8 for cleaning the second development station without actually creating an image.
Using a sub-method similar to that of FIG. As shown in FIG. 15, the image member charge is released by some means, such as the same exposing means that forms the electrostatic image of FIGS. 3 and 10. FIG.
As shown in FIG. 4, the magnetic brush 11 delays the application of any positively charged toner to the discharged image member 1 in the presence of an electric field that promotes the adhesion of the negatively charged toner to the image member 1. Attempt to apply toner. FIG. 16 shows an electric field that applies a slightly larger negative bias to the toner application station 11 than the negative bias used for development (FIGS. 4 and 11). Again, the processing steps of Figure 5 are not used. The transfer step of FIG. 6 is likewise not used.
There is no need to send a printing sheet. As shown in FIG.
The transfer promoting member 23 is separated from the image member 1. The transfer to the transfer promoting member 23 can also be prevented by adjusting the bias of the transfer promoting member 23, as shown in FIG. If electrostatic transfer is done by corona, then all that is required is to turn off the corona. The negatively charged (black) toner on the image member 1 can be removed by a cleaning device 29 as shown in FIG.

The sub-methods of FIGS. 15-18 can be used whenever the device is not in use. For example, the above sub-methods can be used as a routine while the device is warming up. Because this routine does not need to use the melter which requires the longest warm-up.

FIG. 19 shows an image forming apparatus 10 for executing all the three subsidiary methods shown in FIGS. As shown in FIG. 19, an image member 1 in the form of a transparent photoconductive band is placed around a series of rollers so that it can be moved in the path through a series of stations. The image member 1 is evenly charged by the charging station 9 and is image-wise exposed at a first exposure station, such as an LED print head 5, a laser, etc., to form a first electrostatic image. The first electrostatic image has a first polarity determined by the charge from charging station 9.

A first toner having a first color and a first polarity (eg, a negatively charged black toner) is applied by a suitable toner application station 7 to form a first toner image. One is applied to the electrostatic image. Since the polarity of the toner is negative, the toner adheres most heavily to the most charged-emissive portions of the first electrostatic image (DAD development).

The image member bearing the first toner image can be recharged to a negative potential by the charging station 6. (This step may not be necessary.) With or without recharging, the image member was placed behind the image member 1 to form a second electrostatic image. , Imagewise exposed by a second exposure station, such as an LED printhead 12, a laser, etc. The electrostatic image is applied with a second color (eg, red) positively charged toner from the second toner application station 11 already shown. Alternatively, the second electrostatic image can be applied from the third toner application station 13 with a positively charged toner of a third color, such as yellow.

Preferably, both toner application stations 11 and 13 are fast, even at relatively small stations, as described in FIG. 20, so that they have no effect on the first toner image. It is preferred to have a structure that provides a soft magnetic brush that forms images at very high densities.

If the toner colors at the toner application stations 7 and 11 (or 13) are different colors, the image member 1 has two images. Naturally, stations 7 and 1
It is possible that one toner has the same color but different characteristics. For example, one of the two toners may be black magnetic toner and the other may be black non-magnetic toner. Such a combination has certain advantages for certain processes. For the purposes described herein, a combination of non-magnetic black toner and magnetic black toner is
Essentially the same as a two color toner image.

The two color toner image is sent to a processing station consisting of a corona charger 15 and an erase lamp 17. The corona charger 15 is biased to change the polarity of one of the toners forming the two color toner image. For example, a corona charger can apply a negative charge to a two-color image, thereby changing the charge of the applied positively charged toner particles at either toner application station 11 or toner application station 13. You can As known to those skilled in the art, this process is enhanced by the use of an erase lamp 17 located at and / or in front of the corona charger 15 which further weakens the affinity of the toner for the image member 1. be able to.

The processed two-color image is transferred to the transfer promoting roller 23.
Is transferred to a transfer station including an electric potential source 19 that can be inverted, and transfer of toner from the printing sheet, which is sent from the printing sheet supply source 21, is accelerated.

The printing sheet is separated from the image member 1 when the image member 1 passes around a small roller and is sent to the fusing device 25 and finally to the output tray 27. The cleaning station 29 cleans the image member 1 so that the image member can continue to be used during this process.

The above description relates to the operation of the image forming apparatus 10 when the sub method described with reference to FIGS. 1 to 7 is executed. When performing the secondary method shown in FIGS. 8-14, the charging station 9, exposure L
Exposure LE while forming a single color image using ED print head 12 and toner application station 11 or 13
The D print head 5 and the toner application station 7 are turned off. The corona device 15 and the erase lamp 17 are also turned off and the bias applied to the transfer promoting roller 23 from the reversible voltage source 19 is reversed, and as a result,
The red or yellow toner applied by stations 11 and 13 is actually transferred to the printing sheet, while all black toner deposited on the background on the image member 1 contained in either of the stations. The toner is removed by the cleaning device 29.

The sub-methods described with reference to FIGS. 15-18 are performed by the image forming device 10 during cycle up of the device 10, for example, when the device 10 is first turned on for the day. . During the cycle up,
While the fusing device 25 is warming up, the image member 1
Is driven through its endless path. LED print head 12 and toner application stations 11 and 13
One or both of the two are turned on. LED print head 12
Biases the stations 11 and 13 which erase all charge on the image member 1 and promote the deposition of black toner on the image member 10 which remains in the station. Black toner of negative polarity is repelled by the strong negative bias of toner application stations 11 and 13. Again, the corona device 15 and the erase lamp 17 are turned off and the transfer facilitating member 23 is separated from the image member 1 so that the black toner on the image member 1 is subsequently removed by the cleaning device 29. Naturally, no sheet is sent out from the printing sheet supply source 21 during this operation. As noted above, the transfer facilitating member 23 can be maintained in the correct position, but is biased against it to prevent toner transfer.

The operation of the image forming device 10 is controlled by a logic / control device 100 that turns on / off all subsystems at appropriate times, as is well known to those skilled in the art. As shown in FIG. 19, the logic / control device 100
Controls, among other things, the bias applied to the transfer facilitating roller 23, the operation of the corona device 15 and the erase lamp 17 for the operation of the sub-methods shown in FIGS. The apparatus also controls the bias of the development station, including the bias applied to stations 11 and 13 during the subprocess shown in FIGS.

FIG. 19 shows another toner applying station 22.
Is shown. This station can be used to supply a second primary color instead of the color supplied by the station 7 for DAD images. However, it can be used for different purposes to further prevent the toner supplied by the station 7 from moving due to peeling.
More specifically, for this purpose, station 22 contains a transparent toner of the same polarity as the toner of station 7. This station 22 is biased to apply a thin coat of transparent toner over the first toner image formed by stations 9, 5 and 7. This toner does not affect the density.
Because it is transparent. However, if any toner is removed from the image by station 11 or 13, it is likely that it is the top toner, ie,
It is likely to be clear toner supplied by station 22. Eventually, toner from station 7, such as black toner, will migrate within station 22 for delamination. This is because both such toners have the same polarity.

The use of a clear toner application station 22 greatly extends the life of the developer in stations 11 and 13. However, transparent toner has other drawbacks.
Very naturally, black toner gradually moves to the transparent station due to peeling, but this toner is
By measuring the light reflected or reflected or transmitted by the toner at station 22, the transferred toner can be easily measured. By doing so, the effect of toner movement on a properly calibrated system can be monitored, which allows the operator to know when to replace the developing devices at stations 11, 13 and 22.

This feature obtained through the use of clear toner at station 22 is illustrated in connection with the DAD-CAD process. In fact, this feature is particularly useful during all processes of toner-coating electrostatic images in the presence of unfixed toner images of any polarity. Since the DAD development is performed at the station 22, there is a possibility that the transfer to the toner due to peeling to the station may occur to the toner to the stations 11 and 13, both of which are CAD stations. Note that there is a higher likelihood that delamination migration will occur. Therefore, at station 22, projection toner application is preferred.

FIG. 20 shows the toner application station 11.
(And also station 13) is a detailed view of the preferred embodiment. As shown in FIG. 20, a toner application station 11 was first disclosed in US Pat. No. 4,546,060 to Miskinis et al., Dated October 8, 1985, and further to US Pat. , 001, 0
The technique disclosed in No. 28 is implemented. The toner application station 11 includes a housing forming a sump 39 in which the supplied developer is mixed by a suitable mixing helical member 51. The developer, when magnetically saturated, comprises a "hard" magnetic carrier having a coercivity of at least 300 Gauss, preferably 800 Gauss or more. The carrier is at least 20 EM per gram carrier in an applied magnetic field of 1,000 Gauss.
It has an induced magnetic moment of U. The toner is a conventional insulating toner that mixes thoroughly with the carrier (usually called the "developer" combination).

The developer is transferred by a suitable transfer device 53 from the sump 39 to a coating device 41 for coating the electrostatic image carried by the image member 1. The transfer device 53 is well known to those skilled in the art, and can include a valve device that can turn off the station by stopping the supply of the developing solution to the coating device 41. The applicator device 41 also comprises a rotatable non-magnetic sleeve, or rotatable magnetic core 43, which is installed inside a shell 45. The core or shell can be rotated in either direction, but most commercial embodiments rotate the core 43 clockwise to rotate the developer in the shell 45 counterclockwise. Spin at 1,000 revolutions per minute or more. When the shell 45 rotates counterclockwise, the flow of the developer is promoted. As another method, the developing solution can be rotated counterclockwise mainly by rotating the sleeve 45, and the core 43 can also be rotated counterclockwise. In this last case, the rotation of the core primarily serves to mix the developer, as the core actually promotes rotation of the developer in the direction opposite to the counterclockwise direction rotated by the shell 45.

The rapid rotation of the core causes a rapid transition of polarities on the surface of the shell 45 so that when the developer moves through the development zone 55 between the applicator 41 and the image member 1, it causes Carriers with high coercivity usually flip rapidly within the string of carriers. This reversal movement causes the carrier to move rapidly from the shell to the image member and vice versa, to recover lost charge and toner. After several years of using the above equipment and process, it has been found that very soft magnetic brushes provide the highest quality development. The Moshauer patent also pointed out that this brush is soft and can be useful in developing electrostatic images on images that have already formed unfixed toner images of different colors. . The skive 47 suppresses the height of the developing solution fluff, and the developing solution itself is cleared from the sleeve 45 by another skive 49, and as a result, falls into the sump 39 and is mixed there. The developer station itself is mounted on the applicator 41 in such a manner that it faces a set of ski-like members 60 that control the position of the image member 1. Similarly, the print head 12 also includes one or two ski-like members 62 that control the position of the image member 1 with respect to the applicator 41.

The axes of rotation of the illustrated core 43 and shell 45 are the same, but in some commercially available embodiments the axes of the core and shell are offset. When the axis is offset in this manner, the magnetic field in the developing zone 55 is strengthened, and the magnetic field in the portion of the sump 39 facing the developing zone where the developer returns is weakened. This structure is particularly effective when the developer moves only in the shell and the core only performs mixing. This is because the skive 49 has a relatively weak function in such an embodiment.

As shown in FIG. 20, the developer station 11 performs the highest quality development at a very high toner application speed and a very high density. Due to the polarity transitions and inversion of the strings of the carriers themselves, the above concentrations and velocities can be achieved even with very small stations. Due to this soft brush and the movement restraining magnetic field due to peeling in CAD development, the movement due to peeling is surprisingly small.

While the present invention has been described in detail with reference to certain preferred embodiments, it should be understood from the spirit and scope of the invention as described above and as set forth in the appended claims. It should be understood that various changes and modifications can be made without departing.

[Brief description of drawings]

1 is a schematic diagram showing one step of a method according to the invention for forming a two-color image.

FIG. 2 is a diagram showing one step of the method according to the invention for forming a two-color image.

FIG. 3 is a diagram showing one step of the method according to the invention for forming a two-color image.

FIG. 4 is a diagram showing one step of the method according to the invention for forming a bicolor image.

FIG. 5 is a diagram showing one step of the method according to the invention for forming a two-color image.

FIG. 6 is a diagram showing one step of the method according to the invention for forming a two-color image.

FIG. 7 is a diagram showing one step of the method according to the invention for forming a bicolor image.

FIG. 8 is a schematic diagram showing one step of a sub-method of the method shown in FIGS.

9 is a schematic diagram showing one step of a sub-method of the method shown in FIGS. 1 to 7. FIG.

FIG. 10 is a schematic diagram showing one step of a sub-method of the method shown in FIGS.

11 is a schematic diagram showing one step of a sub-method of the method shown in FIGS. 1 to 7. FIG.

FIG. 12 is a schematic diagram showing one step of a sub-method of the method shown in FIGS.

FIG. 13 is a schematic diagram showing one step of a sub-method of the method shown in FIGS.

FIG. 14 is a schematic diagram showing one step of a sub-method of the method shown in FIGS.

FIG. 15 is a schematic diagram showing one step of another four-step sub-method that differs from the sub-method of FIGS. 8-14.

FIG. 16 is a schematic diagram showing one step of another sub-method.

FIG. 17 is a schematic diagram showing a step in another alternative sub-method.

FIG. 18 is a schematic diagram showing one step of another sub-method.

FIG. 19 is a schematic side view of the image forming apparatus.

FIG. 20 is a schematic side view of a developing station.

[Explanation of symbols]

 1 Image Member 2 Image Surface 4 Bottom 5,12 LED Printing Head 6,9 Charging Station 10 Image Forming Device 11 Magnetic Brush 13,22 Toner Application Station 15 Corona Charger 17 Erasing Lamp 19 Potential Source 23 Transfer Accelerating Roller 30 Image Printing Sheet

Front Page Continuation (72) Inventor W. Charles Cassiske United States, New York, 14526, Penfield Weissair Drive, 5 (72) Inventor, Edward M. Eku United States, New York, 14482, Leroy Lake Lord 7988 (72) Inventor Garold F Fritz United States New York 14580 Webster Bending Bow Drive 638

Claims (12)

[Claims] 1. A method of forming a first electrostatic image of a first polarity on a first side of a photoconductive image member and forming a first toner image on the first side. ,
Opposite the first side to apply a first toner of a first polarity to the first electrostatic image and to form a second electrostatic image that registers with the first toner image. Exposure of the image member to the image from the second side of the image member and a first polarity to a second electrostatic image to form a second toner image that registers with the first toner image. And applying a second toner of opposite polarity. 2. The step of applying a second toner to the second electrostatic image is in contact with the second electrostatic image of a developer solution containing a mixture of hard magnetic carrier particles and toner particles. The image forming method according to claim 1, further comprising movement through a development zone. 3. The method of claim 2 wherein the step of applying the second toner comprises making a rapid magnetic polarity transition to the developer as it moves through the development zone. The image forming method described. 4. The rotation of the magnetic core inside the non-magnetic sleeve causes at least a portion of the developer to move through the development zone, whereupon the developer moves and the rotating magnetic core causes the polarity transition. Item 4. The image forming method according to Item 3. 5. The exposure step for an image according to claim 1, wherein the level of charge on the image member below the first toner image is lower than the level of charge in the exposed areas outside the first toner image. The image forming method described. 6. The step of applying a second toner reduces migration of the first toner image due to delamination of the toner,
6. The method of claim 5 further comprising applying toner in the presence of an electric field directed to reduce deposition of the second toner within the charge emitting portion of the second electrostatic image containing the first toner image. Image forming method. 7. A step of uniformly charging a first surface of a photoconductive image member with an electric charge of a first polarity; forming a first electrostatic image of a first polarity on the image member. To expose the image member to form an image, and to form a first toner image on the first side of the image member to form a first polarity image on the first electrostatic image. Applying a first toner, exposing an image member to image to form a second electrostatic image that registers with the first toner image, and first toner image Applying a second toner of a second polarity opposite the first polarity to the second electrostatic image to form a second electrostatic image for registration therewith, The step of applying the second toner brings the developer solution closer to or further from the second electrostatic image. While benefit is rapid magnetic polarity transitions go to the developer, through contact with the image member, an image forming method comprising the step of moving the developer containing a magnetic carrier particles and toner particles hard. 8. A step of forming a first electrostatic image on an image member, a step of applying toner to the electrostatic image to form a first toner image, and a second electrostatic image. Exposing the image member to form an image to form a toner, and applying toner to the second electrostatic image to form a second toner image that registers with the first toner image. And applying a transparent toner to the first electrostatic image after applying the first toner to provide a thin transparent toner coating on the first toner image, Thereby, the image forming method is characterized in that the first toner image is prevented from being moved due to peeling while the second toner is being applied. 9. Forming a first electrostatic image of a first polarity on an image member, and first forming a first toner image on the electrostatic image member to form a first toner image on the image member. Applying toner, exposing the image member to form an image to form a second electrostatic image that is registered with the first toner image, together with the first toner image A step of applying the second toner to the second electrostatic image to form a second toner image to be registered in A toner image consisting of a toner of a second polarity opposite the first polarity, processing two toner images to make the toner substantially one polarity, and a toner of one polarity In the direction of promoting transfer of the image to the image transfer surface. An image forming method for forming two toner images by a first sub-method including the step of transferring the two toner images to the image transfer surface by A single toner image is formed using the step of deciding to form a single toner image with only polar toners and the first sub-method that is otherwise applicable to the formation of a toner image without the use of a processing step. Forming a toner image, the transferring step applying an electric field directed in a second direction opposite the first direction,
An image forming method characterized by a second sub-method of facilitating transfer of an untreated single toner image to an image transfer surface. 10. The process step charges the two toner images with the same charge as on the first toner, and the direction of the electric field applied during the transfer step of the second sub-method is the first The image forming method according to claim 1, which is opposite to the direction of the sub method. 11. A step of forming a first electrostatic image of a first polarity on an image member, and a step of forming a first toner image on the image member to the electrostatic image. Applying toner, exposing the image member to form an image to form a second electrostatic image that is registered with the first toner image, together with the first toner image Applying a second toner to the second electrostatic image to form a second toner image to be registered in the presence of an electric field that promotes toner application of the second electrostatic image. , The developer containing the second toner is moved to contact the image member, one of the toner images is composed of the toner of the first polarity, and the other toner image is composed of the toner of the opposite polarity to the first polarity. A step consisting of two polar toners and one toner The step of processing the two toner images to make them polar and the transfer of the two toner images to the image transfer surface by applying an electric field in a direction that promotes the transfer of toner of one polarity to the image transfer surface An image forming method for forming two toner images by a first sub-method including the step of: Moving the developer into contact with the image member in the presence of an electric field that promotes the adhesion of any first toner onto the image member;
An image forming method characterized by a second sub-method comprising the steps of sending onto an image member and removing the adhered toner from the image member. 12. A first and second toner application station, wherein the first station comprises the first polarity toner and the second station comprises a second polarity toner. The second station applies toner to the first toner image by the first toner applying station when the toner applied by the first toner applying station tends to move to the second toner applying station by peeling. Is installed at the position to apply
Consisting of two toner images of different colors and different polarities,
Means for forming a bicolor toner image, means for processing the bicolor toner image to render the toner substantially one polarity, and in the presence of an electric field that promotes transfer of the one polarity toner, An image forming method, comprising: a means for transferring a two-color toner image onto a transfer sheet, wherein an electric field for promoting the adhesion of the first polarity toner existing in the second toner application station onto the image member. In the presence of a transfer member, the transfer member is operable to move the image member through the second toner application station and the adhered toner having the first polarity can be transferred through the transfer member on the image member. An image forming method comprising: a means for eliminating the toner and a means for removing the toner having the first polarity from the image member.