JPH0798529A - Formation method of composed toner image and write apparatus used for it - Google Patents

Abstract

PURPOSE: To provide a method for forming two toner images in the single frame of an image structure and a light device used for it. CONSTITUTION: Synthetic toner images composed of a first toner and a second toner are formed on the image structure 1. The electrostatic images of a first polarity are formed on the image structure 1 and toned by the first toner of the first polarity. The image structure 1 is exposed in terms of images so as to form the second electrostatic images of the first polarity. Exposure is performed while performing overlapping on the part of the image structure 1 under first toner images and the electric charge of the first polarity of a photoconductive layer under the first toner images is prevented from repelling the toner and being forced to an area where the second electrostatic images are discharged. The second exposure is performed through the base of the image structure 1 and it is preferable to completely expose the part of electrostatic images under the first toner images. It is convenient to expose the web image structure 1 through the base by a printing head provided in a printer. The printer is provided with the printing head and a positioning bar for placing a lens at an appropriate position from the image structure 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to the formation of two or more toner images in a single frame or area of an image construction. Although not limited thereto, the present invention is particularly applicable to a method and apparatus for forming an accent color image on a single frame of an image construct in one path.

[0002]

2. Description of the Related Art US Pat.
No. 8 is representative of many references that describe the process of uniformly charging a photoconductive image member and imagewise exposing it to produce an electrostatic image. is there. Toner is applied to the electrostatic image to produce a toner image. Development of the discharged areas is typically used in this process. Therefore, the applied toner has the same polarity as the electrostatic image. Toner images are deposited in the areas of least charge (most discharged areas) to form a toner image with maximum density in the image areas that are most exposed.

Although not absolutely necessary in this process, the image member has a charge of the same polarity as the original charge,
It is uniformly charged again. Then, in general, the second toner is applied to the part of the image forming body which is not covered with the first toner image.
Are imagewise exposed to form an electrostatic image of. The second electrostatic image is toned again with toner having the same polarity as the charge that produces the second toner image. This process can also be repeated for a third electrostatic image toned with a third color toner to form a three color image. Two
The color image (or more) is transferred to the copier in a single step and mixed in a single step.

Although not necessarily limited to such applications, this process is quite commonly used to provide accent color prints or reproductions using laser or LED printhead electronic exposure. This process has many advantages in accent color applications. It eliminates the tedious and expensive steps normally used to overlay images during transfer.

If separate exposure stations are used, the process can produce accent color output at the same rate as single color output. It is important that the second and subsequent toning steps do not disturb the first toner image. Otherwise, toner from the first toner image enters the second developing station and mixes (hereinafter referred to as "scavenging"), the second toner
Toner from the developer station of the above can be deposited on the first toner image (hereinafter referred to as "overtoning"). Recharging between images reduces overtoning.

Most of Mose Howell's prior art recommends the use of projection toning in the second and subsequent toning steps in order not to disturb the first image. The Mosehower patent suggests that excellent results can be obtained using a high coercivity carrier in a two-component magnetic brush with a rotating magnetic core. Mosehower's method has a higher process speed with less color mixing than other high density, high speed equipment.
It provides a high density image.

US Pat. No. 4,778,740 (Matsushita) makes the following note regarding the problems observed in such systems. That is, if the second electrostatic image includes a discharged area in the immediate vicinity of the first toner image, the first toner will tend to mix into the second image. The suggested solution to this is to leave one pixel gap from the first image during the second exposure. This can be done in an electronic exposure system where the registration between the two exposures is very accurate. However, it requires good stacking,
A light untoned area between the two images, ie a white line,
The so-called "hello" appears.

US Pat. No. 5,025,292 discloses a system in commercial use. In it, a series of color separation images are formed using liquid development in a single image member. The first image is heated, dried and fixed during the second exposure. The second exposure is performed through a transparent support that produces an electrostatic image that actually overlays the first color image. The electrostatic image is then toned to form overlapping color toner images. This process is also performed for the development of the discharged areas and the image member is recharged between images.

Many prior art patents disclose exposures through a photoconductor base for various purposes. Usually, the same magnetic brush is used for cleaning and development, or exposure and development are performed simultaneously. For example,
See US Patents 3,703,335, 5,159,389 and 5,053,821.

In solving the problem of the dry toner mixing from the first toner image into the adjacent second electrostatic image, the first problem is
It has been found to be significantly affected by the charge on the image member below the toner image. This charge occurs predominantly in one of the first two charging steps, perhaps in the second charging step. That is, the charge from the second charging step does not remain completely on the surface of the toner, but rather travels through the toner to the photoconductive surface itself (despite the insulating properties of the toner).
This charge is of the same polarity as the initial charge and the new charge on the toner itself. As described above, since the toner and the image forming body have the same polarity, the toner tends to be repelled by the image forming body.

If the second electrostatic image does not have a discharge area adjacent to the first toner image, the charge from the first and / or second charging steps located next to the toner image will be transferred to that space. It will prevent the toner from migrating. However, if the adjacent space is exposed in the formation of the second electrostatic image, its charge is dissipated and the toner is now repelled by the charge still under the toner and is no longer by itself. Enter an unprotected space. We call this a "toner gush."

Our solution to this problem is to discharge this charged portion that repels the first toner image. A second (and subsequent) exposure is preferably used to discharge this charge, for example by exposing it through the base of the imaging member. Portions of such exposure are allowed or designed to overlap with the first toner image. This discharges or reduces the charge on the photoconductor that would otherwise have a tendency to repel the toner. By losing this charge, the toner is repelled, eliminating the tendency to move to the adjacent discharge area of the second image.

The charge remaining on the first toner image tends to reduce the overtoning by the second image in the overlapping area. However, it seems to be the case with some overtoning. According to the preferred embodiment, this effect becomes less pronounced by superimposing the bright side of the two images on the dark side. This is easy to do if the second image is bright, but can also be done if the first image is bright.

Accordingly, it is an object of the present invention that at least a first image on the image member is less prone to one of the images moving to an adjacent part of the image member which is not intended to be part of the toner image. And providing a second toner image. This and other objects are achieved by the method according to claim 1.

According to a preferred embodiment, the method uses an image member having a photoconductive layer, preferably a transparent support. A first electrostatic image is formed on the image member and has a first polarity and a first polarity to form a first color toner image.
The toner is toned by applying a first dry toner having the above color. The second electrostatic image is formed by imagewise exposing the image member with an electric charge of the first polarity onto the image member, preferably through a transparent support. . The second electrostatic image is developed by applying a second color toner having a first polarity to form a second color toner image corresponding to the exposed portion of the electrostatic image. It

Preferably, in addition to producing the second electrostatic image, the exposure causes the first image portion to discharge a portion of the image member underneath the toner image that is associated with the second electrostatic image. Overlay on toner image. In a preferred embodiment of the present invention, the exposure feature passing through the support can be used in the process of color imaging as well as accent color imaging. The exposure through the support has many advantages over the previous image avoidance exposure.

For example, there is more room for the printhead writer assembly on the side of the image member opposite the toner station. The printhead will probably not get smeared by the flying toner. Development of charged areas is easy to use. Another advantage of exposure through a support is that simple and accurate placement of the print writer assembly can be easily designed. Therefore, one of the present invention
One purpose is to provide a printhead writer assembly that is easy to install for exposure through a web support. This assembly is particularly suitable for carrying out the method of claim 1, but can be used in other applications as well.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 2A-2F show a method of forming two dry and unfixed toner images on the same area or frame of image construction 1. Although this toner need not have different colors, multicolor application is the most attractive use of this process, and the following description is also in terms of color. Further, for the sake of explanation, 2
Although a color image of colors is described, the same process can be applied to three or more different color images.

According to FIG. 2A, the image construction 1 comprises a support 3 and a photoconductive layer 5. It is a typical image construct used in electrophotography. If the support 3 is not electrically conductive, the imaging member comprises a conductive layer between the support 3 and the photoconductive layer 5. Much more complex than described here may include charge generation layers, charge transfer layers, barrier layers and overcoat layers. However, for the purposes herein, the image member is simply described as a support with a photoconductive layer.

In FIG. 2A, the photoconductive layer 5 is uniformly charged with a first electric potential, for example, a negative electric charge. Figure 2
As shown in (B), an electrostatic image is formed on the image forming body 1 by imagewise exposing the charged photoconductive layer 5, for example, by exposing the photoconductive layer 5 with the LED print head writer 7. Is generated. In FIG. 2C, the electrostatic image is
A charge of a first polarity to produce a first toner image,
In this case, toning is performed by applying a dry toner having a negative charge. This toner is preferably of a first color, for example black.

As shown in FIG. 2D, the image construct 1 is composed of
Again, it is charged with a first polarity charge, ie a negative charge.
In FIG. 2 (E), a second electrostatic image is formed on the image member by imagewise exposing the image member, for example, by another or the same LED printhead writer 7. It In FIG. 2F, the second electrostatic image is toned by applying the second toner having the first polarity. The second toner adheres to the image member in the exposed portion of the second electrostatic image to produce a second toner image.

The second toner image can be of a second color, for example red. The image construct 1 is now black in the exposed parts of the first image, red in the exposed parts of the second image and free of toner in the previously unexposed parts. Additional images can be placed in the areas that have not yet been exposed, using differently colored toners to produce a three or more color image. The process may use a conventional optical copier, but preferably an electronic printer and copier.

The step of recharging the first member prior to the second exposure, shown in FIG. 2D, can theoretically be omitted. That is, the image construct under the conditions shown in FIG. 2C contains a charge in the unexposed areas, which charge can be used to form a second electrostatic image. However, it ensures that both toned and untoned areas are placed on a substantially uniform charge, so that the next toner image will only accumulate in the exposed areas of the second electrostatic image. It has been found that little overtoning occurs when the image member is recharged to The second charging step can also be used to compensate for material changes in the two toning steps.

FIG. 3 illustrates the problems encountered with the exposure producing the second electrostatic image. The exposure is also shown in FIG. 2 (E). As shown in FIG. 3, the toner at edge 11 of the first toned image tends to migrate to the exposed areas of the second electrostatic image adjacent that edge. That is, when the second electrostatic image includes the exposed area directly adjacent to the edge of the first toner image, as shown in FIG.
Toner along the edge 11 of the first toner image tends to move to the left.

This problem has been solved in the prior art by programming the second exposure so that it is not adjacent to the first toner image. However, this requires precise registration of the images, leaving untoned lines between the two toner images, which is unacceptable for high quality images. In an experiment and analysis on this issue, the uniform charging step described in FIG. 2 (D) flattens the charge on the combination of the image member and the first toner image, on the one hand, to charge of the first polarity. Was found to be the cause of the transfer of the toner to the image forming body through the first toner image.
This charge has the same polarity as the charge originally placed on the toner, thus further releasing the toner image.

The unfixed, dried first toner image is repelled by this charge on the image member. As long as the charge next to the toner image has the first polarity, there is no place for the toner to go. However, the second image is shown in FIG.
When exposed as shown in FIG. 3, exposure immediately adjacent to the toner image, eg, exposure of image edge 11, removes the charge holding the first toner image in place. At this point, the edged toner of the first toner image is repelled by the charge on the image member beneath that toner and moves to the immediate next to the exposed area. This spreads the first toner image and prevents proper toning of a portion of the second electrostatic image.

The first solution to this problem is shown in FIG. In FIG. 4, the second exposure, which corresponds to that shown in FIG. 2E, is preferably carried out through the support 3. This exposure dissipates the charge underneath the portion of the first image that tends to release toner, as shown in FIG. 4, and can overlap under the first image. In this respect,
The toner of the first image is not repelled by the charge beneath it. The charge is no longer present and there is no reason to move it to the adjacent exposure area as shown at edge 11 in FIG.

As shown in FIG. 2 (F), when the second toner image is applied, the toner adheres to the area discharged at a good image density to the original end of the first toner image. To do.
Depending on the strength of the exposure weight, the exposure may cause some overtoning. For this reason, the darker image is exposed to match the desired final image, and the brighter image is magnified where it is intended to touch the dark image.

The desired amount of exposure overlap depends on the materials used and can be empirically determined by those skilled in the art. The amount of weight is preferably designed in consideration of exposure of a bright image. Either the first or the second image may be a bright image. However, first, a dark first image and a bright second image are discussed below. The weights combine the first image and the second image, as described below, to extend the exposure to the side of the bright image pixel where the bright image pixel is adjacent to the dark image pixel. It is performed by an appropriate algorithm. The weight is spread as small as one picture element,
It has a beneficial effect on the tendency to move the toner to the second electrostatic image.

This approach has the additional advantage of blocking white lines between images when the exposure weight is imperfect. If different printheads are used for exposure (see FIG. 1), the system will produce productivity not possible with transport station registration. However, the large number of printheads increases the exposure overlay problem. Such an overlay problem causes white lines between adjacent images. This approach fills such white lines.

FIG. 5 shows an extension of FIG.
In FIG. 5, the electrical signals that make up the first electrostatic image and the second electrostatic image are fully merged so that the second exposure exposes the entire area under the first toner image. It This approach is suitable when the first image is always darker than the second image and is electrically very simple. The way is the first
There is the advantage of ensuring that the toner image is not prone to mix into the exposed portions of the second electrostatic image. It also removes the charge on the photoconductor that tends to repel the first toner image. This reduces the tendency of the first toner image to be scavenged by the second toning process (FIG. 2 (F)). However, this approach may cause more overtoning and may limit the available colors.

In order to reduce overtoning for a material, underneath some or all of the first toner image is exposed with a different intensity than the exposure of the area in which the second toner image is to be obtained. The way is preferable. The amount of exposure and the range of exposure are empirically determined by the person skilled in the art for the material used. What is important in this manner is to at least dissipate the toner-repelling charged portions of the first toner image that are adjacent to the exposed areas of the second electrostatic image.

In the manner shown in FIG. 4, where the overlap is limited to the portion of the first toner image adjacent the exposed area of the second electrostatic image, a relatively simple algorithm can be used. . In digital accent color copiers or printers, images are scanned or stored in the form of iconic bitmaps. Adjacent colors are detected by comparing adjacent pixels of input data from a scanner or previously stored bitmap. If, for example, the first pixel is a light color of the second color and the second pixel is a dark color of the first pixel, the second pixel is (first exposure In the second exposure (in addition to being exposed in), it is also exposed. This produces a second color into the adjacent first color.

Next, the algorithm compares the second picture element with the third picture element and expands the overlap if necessary. If one pixel is required to overlap and the second pixel already overlaps, then if something is found in the third pixel, nothing will be done in the overlap, Note that the algorithm can skip comparing the third pixel with the fourth pixel. After a row of adjacent images are overlaid, that row is compared, pixel by pixel, with the adjacent pixels in the previous row. In the simple case of making one weight for one picture element, if one picture element is immediately overlapped in any column, then the next pair is compared. If adjacent images are found, the separation for the bright image is greater, so that both images are exposed in the second exposure.

In the example shown in FIG. 5, the algorithm is much simpler. As noted above, weaken or not weaken the intensity of the portion where the second image overlaps the first image,
The second image is added to the first image. The exposure below the first image tends to increase the coercivity of the first image, thereby reducing the scavenging effect. At the same time, it tends to reduce any charge associated with the first image when the second image is toned, thus increasing overtoning. The amount of this overtoning is determined by the amount of charge remaining across the toner in the first image itself.

In the experiment, for most toners, for example,
Even with substantially insulating toners, the above has been shown to be likely only between 200 and 250 volts. Therefore, several options are available with this system. The second image can be toned with a toning bias provided to prevent toning of areas with potentials above 200 volts. Second, the exposure intensity of the over-exposure may be reduced so that the photoconductor retains most of the residual charge. Third, the first image can be overtoned, and the device has a bright image,
An extended and overtoned image can be used.

The latter method is preferable. Adjacent to the statue,
Where one of the colors is substantially brighter than the other, it is often desirable. For example, a black image next to a dark blue or dark red image is more practical than a black or dark red or dark blue image next to a bright yellow, light blue, bright orange, or bright pink image. Are extremely rare. Therefore, according to a preferred embodiment of the present invention, when a dark image is initially placed, its exposure is done exactly to match the desired appearance of the final image, i.e., not expanded. The opposite is done similarly. That is, the lighter colors are laid out first and the second darker colors laid. In each case, the second exposure is under a portion of the first toner image.

In more sophisticated imagers, grayscale exposure is used. In such a device, black toner can be used to create a range of image densities from dark black to light gray. Almost all images are processed using the black station initially placed to create a black image without expansion and to expand all other colors adjacent to it to black.

However, it will be appreciated that low density black (light gray) pixels rarely occur next to much higher density pixels of medium dark color such as red. Is within the skill of one in the art. In this case, the black image is expanded and the red image is not expanded. The first step in an algorithm that looks at two pixels of different colors is to first determine which is brighter. Then that part of the bright image is expanded. Although this approach preferably uses a wide range of tow tables, it is not complicated and is within the skill of those in the art. The previously described pixel-by-pixel algorithm for overlapping images for the case of a dark first image can be used if the second image is dark.

Note that the embodiment in FIG. 5 has the advantage of reducing the scavenging of the first image because it holds the first image to the image construct with greater force during the second toning step. Get it. However, the embodiment of FIG.
Requires a good superposition of the second exposure to prevent edging of the second color on the portions of the first image that are not intended to be adjacent to the image of. On the contrary,
The embodiment shown in FIG. 4 has the advantage of eliminating the overlay problem if the two images interfere, but does not add any advantage to the overlay problem if the images are not adjacent.

As explained in FIGS. 4 and 5, the support 3 must be transparent to the exposing radiation in order to be exposed through the base. The conductive layer 9 is generally arranged between the support 3 and the photoconductive layer 5 and must also be transparent. Transparent supports and transparent conductive layers are well known in the art. The transparency of the conductive layer is generally obtained by making a normally non-transparent material an extremely thin layer.
Nickel, tin, cuprous iodide and other conductive materials can be used for this application.

The charge under the first toner is dissipated by frontal exposure if the material making up the first toner image is selected to be transparent to the active radiation of the second exposure. be able to. This is a known method for supplying overlapping toner images. For example, an infrared laser is used for actinic irradiation with a suitable photosensitive photoconductive material in photoconductive layer 5.

Thus, the toner is opaque to visible light and gives a suitable color, but a material transparent to actinic radiation is chosen. Frontal exposure is feasible, but less desirable than exposure through a support for accent color applications. This is to limit the toner design and the order of the colors in which it is placed. Further, as shown in FIG. 1, use in the process of color applications where the exposure through the support is desired to superimpose the toner image, ie when the earlier image partially obstructs the next exposure. You can

It is well known that the initial toner image preferably consists of small particles, which are well retained for the image member. It is well known that the second toner image is composed of large toner particles, and the large toner particles have good aerodynamic characteristics for projection toning. For example, referring to FIGS. 4-6, the first toner image is comprised of small size dark toner particles, eg, black toner particles having an average diameter of 8 microns.

FIG. 4, as shown in FIG. 5, exposure is performed through the base with the desired overlap to produce a second electrostatic image, but the first toner image does not move. . In FIG. 6, for example, the second electrostatic image is toned with large, bright color toner particles, such as yellow, light blue, orange, and pink toner particles having an average diameter of 12 microns. The particles behave well to use projection toning to provide a second toner image that overlays the first toner image.

FIG. 7 illustrates another feature that reduces the tendency of toner ejection as well as scavenging. First
2), for example, after the step of producing a toner image as shown in FIG. 2C, but before the second charging step described in FIG. The blanket is exposed by irradiation. Upon irradiation, the image member is exposed through the transparent support 3 to remove as much negative charge as possible from the first electrostatic image on the image member.

There, the surface tension causes the toner to be held on the image member and compensate for the positive charge (electron holes) moving through the photoconductive layer which is attracted by the negative charge still remaining on the toner itself. To do. Although this step is somewhat destroyed by the charge in the second charging step, it is still expected to reduce the tendency of the toner jets in the second exposure step. this is,
Obviously, this is due to holes remaining near the surface of the photoconductive layer despite the second charging step. By overlapping the second exposure (FIGS. 4 and 5), more holes are attracted toward the surface, helping to hold the toner and immobilizing it.

FIG. 1 shows an apparatus for producing a two-color image. In this device, the second exposure is performed through the base. In FIG. 1, the image forming body 1 is in the shape of an endless belt that travels around a series of rollers including a tension roller 16 and a drive roller 18, and a series of electrophotographic stations known in the prior art are connected in series. Pass through.

The image forming body 1 is charged by the charging device 10 to a uniform potential, for example, a negative potential. The image formation 1 is imagewise exposed by an exposure device, for example an LED printhead 7, to produce a first electrostatic image. The first electrostatic image is toned at the first toner station 15 by applying toner of the same polarity, eg negative polarity, as the first charging station 10 and of small size particles, eg 8 micron particles. . Toner is thus applied to the areas discharged by the exposure station 7.

The image construct is provided with an additional charging station 20.
Recharged by. The charging station flattens a first polarity charge on the image member at a predetermined level.
This level need not be the same as the charge applied by station 10. However, the image construct is
Prior to recharging, it is exposed by the erase lamp 19 with general blanket radiation through its support. This causes the toner to be held firmly in the image member despite the charge from the charging station 20, as described above.

The magnetic scavenger 27 is arranged to attract the carriers that were accidentally picked up by the image member in the first toning step. The position of the scavenger 27 in front of the toning station 25 is to prevent the carrier used in the station 15 from carrying dark toner into the station 25.

The image construct 1 is then placed inside a second exposure station, for example the image construct 1, through which transparent support a second electrostatic image is produced. It is imagewise exposed by the exposing second print head 17. The second electrostatic image is toned by the second toning station 25. Second toning station 2
5 preferably applies toner of a different color than the color applied by station 15 to produce the second toner image on the image member. Also, particles larger in size than the toner, eg, 12 microns, are desirable, thereby forming a two-color or multicolor image on the image member.

The paper is sent from the paper feeder 29 to
The color toner image is brought into overlapping contact. The two color toner image is transferred to a sheet at a conventional displaced roller electrostatic transfer station 31 which leaves the image member as it rotates around a small roller 24. The paper is transferred to the fuser 35 by the vacuum transfer device 33, where the two-color image is fixed on the paper. The sheets are finally stacked in the output tray 37. The image member is cleaned by the cleaning device 39 so that the process can continue. This apparatus processes a two-color image at twice the speed as compared with the conventional method in which images are formed in separate frames and transferred in superposition. The device also avoids the complication of superimposing the two images due to the associated complex receiving process.

Toning stations 15 and 25 are 1991
US Pat.
It is preferable to configure as No. 001,028. For high quality, the first toning station is separated from the image member 1 by a distance less than the fluff of a magnetic brush. Thus, the brush is in direct contact with the image member and provides a high density image. The second toning station 25 has a sufficient distance that the fluff does not come into direct contact with the image construct 1.
Being separated from. Station 25 AC bias
The components serve to provide the desired density of the second image despite the gap between the fluff and the image construct.

8-15 show details of a linear printhead writer device 50 suitable for use as printhead 7 or printhead 17 of FIG. However, the construction is particularly suitable for placement on the back side and is therefore particularly applicable to the printhead 17 of FIG.

With reference to FIGS. 8, 9 and 13, a linear printhead writer device 50 includes a linear radiation source, eg a linear LED array (FIGS. 9 and 15), and a linear focusing means, eg a self-hook lens ( A linear lens 54, such as the Hitachi product name), and a suitable support housing. The LED array is supported by a support tile 64 (FIG. 8), which is supported by a mother board 62, which in turn is supported by a base plate 60. The base plate 60 is fixed to a pair of supports or reference plates 56 and 58 located at both ends thereof.

As shown in FIG. 13, the lens 54 is fixed to the lens support 55, and a pair of end supports 67 and 69 using the temperature compensating means described below are attached to the support 55. . Each of the end supports 67 and 69 includes a threaded hole 76, which supports plates 556 and 58.
It is arranged on a straight line with the stupid hole 66 (FIG. 8). The screws 65 each include a washer 68 (FIGS. 9 and 15) and are inserted into the screw holes 76 through the holes 66. Screws 65 can be moved within holes 66 to position lens 54 relative to LED array 52 and are used for final factory adjustment of these two parts.

According to FIGS. 8 and 9, one positioning bar 70 is installed between the support plates 56 and 58. LED array 52, lens 54 and positioning bar 70
Are all parallel to the Z axis and elongated. The orthogonal system X, Y and Z axes are shown in FIG. The upper surface of the positioning bar 70 is
As shown in FIGS. 9 and 15, it is in contact with the image construct 1 and adjusts the distance (in the Y-axis direction) between the image construct 1 and the lens 54 and the LED array 52. Factory and field adjustment of the positioning bar 70 is performed by eccentrically installing the positioning bar 70 on the shaft 74. Shaft 74 is attached to support plates 56 and 58. Knob 72 rotates shaft 74 and is used to rotate bar 70. Bar 7
Since 0 is eccentric with respect to the shaft 74, the top surface of the bar 70 will be LE as the bar 70 rotates.
It moves so as to move toward and away from the D array 52.

The focus of lens 54 on both conjugate axes is best shown by referring to FIG. 15, where unnecessary details have been omitted. In the factory, the writer device 50 is mounted on a suitable fixing device for adjusting the focus (see, for example, US Pat. No. 4,928,139, which is incorporated herein by reference). Lens 54 is moved through its fixture until LED array 52 is imaged by lens 54 at the desired linear exposure position 78. The linear exposure position 78 is also parallel to the Z axis.

This movement is accomplished by moving the screw 65 within the burred holes 66 of the plates 56 and 58. When the proper focus is obtained, screws 65 are tightened to secure lens 54 to LED array 52 and plates 56 and 58. Factory adjustment of the positioning bar 70 can be performed by simultaneously rotating the knob 72 and rotating the positioning bar 70 about an eccentric shaft 74.

A long web, for example a web of the same thickness as the envisioned imaging member 1, will determine whether the proper side of the web will be positioned at the exposure position 78 when the knob 72 is rotated. For ease, it is stretched across the bar 70. Focus determination can also be performed using any suitable device known in the art. The device 50 is shown in FIG.
When inserted into the image forming apparatus shown in FIG. 1, the apparatus 50 is fixed to the mechanism plate of the image forming apparatus.

As shown in FIG. 15, the positioning bar 70 intersects the path of the image member 1 and therefore the image member 1 is lightly pressed from its normal path, for example the rollers 16 and 1 of FIG.
It is located away from that path during the eight. If the toning stations 15 and 25 have parts that control the position of the image member 1, the bar 70 will cross the image member path between the development stations. Thus, the positioning bar 70 partially determines the path of the image construct 1.

During setup, a copy or print is made and the image resolution is measured or observed. At this point the knob 72 is rotated and the imaging member 1 is moved towards or away from the lens 54. This movement is
Using the back position shown, the first side 77 of the imaging member 1 having the radiation sensitive layer is aligned with the exposure position 78. The exposure position 78 is, of course, fixed within the image forming device by the fixing means of the assembly 50.

The positioning bar 70 has a function of moving the lateral position of the image forming body 1 in order to secure the sensitive portion of the image forming body 1 at an appropriate position with respect to the exposure position 78. This positioning structure does not rely on the use of springs to press the printhead device against the support member or the image member itself. The printhead device is fixed to the mechanical plate of the device. Very precise positioning of the printhead in the device is not important if the bar 70 intersects the path of the image construction 1.

Positioning bar 70 is shown in the figure so that it can be adjusted as a unit from one end by rotation, as described. Alternatively, an eccentric mount may be provided that allows in-situ adjustment of each end of bar 70 to the exposure position. This is usually not necessary. Because the adjustment of the distortion of the lens 54 (using the screw 65) at the factory is the exposure position 78 and the bar 7
This is because the parallel relationship between 0 is secured.

FIG. 10 illustrates another embodiment. In FIG. 10, two positioning bars 70 and 80 are arranged on both sides of the lens 54, both in contact with the image construct 1.
This structure is very similar to the embodiment shown in FIGS. It has the advantage that the position of the image construction 1 can be accurately determined without consideration of the orientation of the assembly 50 in the device. However, the embodiments shown in FIGS. 8, 9 and 15 have the advantage of simplicity and the risk of being overly limited and not having the conditions that occur with two positioning bars. is there. Note that one or both of the positioning bars can be adjusted, depending on the amount of adjustment desired.

The image construct 1 has a slight break when in contact with the positioning bar 70. Because the direct installation of the assembly 50 is such that the imaging member 1 will be positioned by the positioning bar 7
This is because it is assumed that the path of the image construct 1 and the positioning bar 70 cross each other so that the position can be controlled by 0. Positioning bar 70 is shown as rotatable only to adjust the distance from lens 54. However, the positioning bar can also be a roller which can rotate with the image formation 1. This has the advantage of reducing the friction between the bar 70 and the image member 1, but
However, the eccentric installation of the bar is somewhat more complicated.

11 to 14 illustrate a temperature compensation device for the lens 54. As described above, the lens 54
Is fixed to the lens support 55, which in turn is rigidly fixed to the end supports 67 and 69. When an LED array is used, it gradually heats the lens and lens support. The lens and lens support are made of similar materials and expand simultaneously. However, the housing, eg, base plate 60, does not necessarily expand at the same rate. Therefore, it is customary to provide a coupling for temperature compensation between the housing and the lens support.

As shown in FIG. 14, the lens support 55 has a pair of pins 82 at both ends. This pin has an axis oriented in the X direction (FIG. 8) and traverses the longitudinal direction (Z direction) of the lens support 55. The pin 82 is inserted into a back hole 84 in the end supports 67 and 69 as best shown in FIG.

Thermal expansion in the Z direction, if uncompensated, will cause buckling of the lens support 55. Such thermal expansion is allowed due to the loose fit between the pin 82 and the dumb hole 84. Pin 8 in stupid hole 84
The actual position of the two is controlled by a suitable shock absorber 90, for example a spring or elastomer, which shock absorber is arranged to resiliently resist movement of the pin in the Z direction away from the center of the lens support 55. ing. Shock absorber 9
0 is an end support 67 by a shoulder screw 86 that is spring-loaded.
And 69. They are preferably rubber shock absorbers that allow the screws 86 to be loosened and tightened to alter the force exerted on the pins 82.

This method of thermal compensation has a feature that can be clearly distinguished from the conventional method of damping the vibration in the Z direction. The vibration of the lens 54 causes a slight movement of the image. The degree of significant imperfections that such movement causes to the final image depends on the degree of vibration. Prior art temperature compensators that firmly secure the lens support at one end do not have the effect of damping such vibrations. However, FIGS.
The approach shown in FIG. 14 dampens vibrations in addition to allowing thermal expansion. Note that both ends of the lens support are separated from the housing by a dampening structure 86. Moreover, the damping structure itself absorbs many vibrations without connecting it to the lens support 55. If one end of the lens support is fixed and the other end is free to move, as in the conventional thermal expansion approach, the vibrations will be completely transferred to the lens support via the fixed end. Let's do it.

In this case, by providing it at both ends and further by providing an elastic damping structure, the vibration from other parts of the machine transmitted to the housing does not transmit to the lens to a certain extent. In addition, the preferred rubber shock absorber for the shock absorber 90 is used to make adjustments to the damping force that can be adjusted to damp particular frequencies that are more troublesome in certain devices. The lens support 55 is secured to each of the end supports 67 and 69 using a shoulder screw (not shown) which is secured to the lens support hole 96 through a cap hole 98 in the end support.
The shoulder screw is tightened against a spring mounted between it and the end support.

The invention has been described in detail with reference to the preferred embodiments. However, it will be appreciated that variations and modifications can be accomplished within the spirit and scope of the invention as described and claimed.

[Brief description of drawings]

FIG. 1 is a schematic side view of an image forming apparatus.

2A to 2F are schematic side sectional views illustrating steps of an image forming method.

FIG. 3 is a schematic side cross-sectional view illustrating various aspects of the image forming method.

FIG. 4 is a schematic side sectional view illustrating various aspects of an image forming method.

FIG. 5 is a schematic side cross-sectional view illustrating various aspects of the image forming method.

FIG. 6 is a schematic side sectional view illustrating various aspects of an image forming method.

FIG. 7 is a schematic side sectional view illustrating various aspects of an image forming method.

FIG. 8 shows a partial perspective view of an LED printhead writer assembly.

FIG. 9 shows a side view of another embodiment of an LED printhead writer assembly.

FIG. 10 shows a side view of another embodiment of an LED printhead writer assembly.

FIG. 11 shows a side view of another embodiment of an LED printhead writer assembly.

FIG. 12 shows a partial perspective view of an LED printhead writer assembly.

FIG. 13 shows a partial perspective view of an LED printhead writer assembly.

FIG. 14 shows a side view of another embodiment of an LED printhead writer assembly.

FIG. 15 shows a side view of another embodiment of an LED printhead writer assembly.

[Explanation of symbols]

 1 ... Image construction body 3 ... Support body 5 ... Photoconductive layer 52, 55 ... Irradiation source 54 ... Focus device 56 ... Support housing 70 ... Positioning bar 77 ... First surface 78 ... Exposure focus

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 15/00 303 15/02 102 15/04 111 9122-2H 15/22 105 B 21/08 ( 72) Inventor Eric Karl Sterter, USA, New York, 14618, Rochester, Warrington Drive, 285 (72) Inventor, Esung Energy, USA, New York, 14450, Fairport, Great Garland, Rise, 15 (72) Inventor Frank Joseph Ketter United States New York 14468 Hilton Salmon Creek Drive 83

Claims (12)

[Claims] 1. A process of forming a first toner image comprising dry toner particles having a first polarity on an image member (1), and an image member (1) having the first toner image. First
Charging an electric charge having a polarity of 2), irradiating the charged image forming body (1) imagewise to generate an electrostatic image, and the electrostatic image having a first polarity. A step of applying a second toner to form a second toner image, wherein the imagewise irradiation includes at least a partial overlap with the first toner image. The method of forming a composite toner image, wherein the discharged area of the second electrostatic image is adjacent to the first toner image. 2. Forming a first electrostatic image of a first polarity on the first side of an image member (1) having at least one photoconductive layer (5) on the first side. Applying a first dry toner of a first polarity to the first electrostatic image to form a first toner image on the first surface of the image member (1);
A step of uniformly applying a charge having a first polarity to the first surface of the image construct (1) and imagewise irradiating the photoconductive layer (5) to produce a second electrostatic image. And a step of applying a second dry toner to the second electrostatic image without fixing the first toner image to form a second toner image on the first surface of the image member. In the method of forming a synthetic toner image, the image forming body (1) has a transparent support (3), and the imagewise irradiation is performed through the transparent support. Image formation method. 3. The imagewise irradiation step comprises dissipating the first toner image in order to dissipate the charge of the first polarity that tends to repel the toner particles that make up the first toner image. The method of claim 2 including the step of illuminating at least some areas of the underlying image construct. 4. The method of claim 3, wherein the irradiating step comprises irradiating the entire area under the first toner image. 5. Irradiation underneath the first toner image comprises a second irradiation
The method of claim 3, wherein the method is limited to illuminating underneath a portion of the first toner image that is adjacent to a discharged portion of the electrostatic image of. 6. The method further comprises after the step of forming the first toner image and before the step of irradiating to form the second electrostatic image. 3. The method of claim 2 including the step of uniformly charging the to a first polarity charge. 7. The step of forming the electrostatic image comprises the step of applying a charge of a first polarity to the first surface of the image member (1) and the step of forming the image member from the first surface. Irradiating selectively. 8. The method comprises the step of uniformly illuminating the image member after the step of forming the first toner image and before the step of uniformly charging the image member. 7. The method according to claim 6, characterized in that 9. The method according to claim 8, wherein the step of applying the second dry toner comprises applying a toner of a color lighter than the color of the first dry toner. 10. An elongated linear irradiation source (55) in a light device comprising a linear printhead for use in a web-shaped image construction having at least one irradiation-sensitive layer on a first side (77). And an elongated linear focusing device (54) for focusing the irradiation from the linear irradiation source to an elongated exposure position, and in relation to fixing both the irradiation source (52) and the focusing device (54) to each other, And a support housing (56) for fixedly supporting the exposure focus (78) of the illumination source, wherein the focusing device (54) and the exposure focus (78) are elongated in the Z direction. The position of the image member (1) having a radiation-sensitive layer, which is fixed relative to the image member (1), is elongated in the Z direction and is supported by the housing (56) to engage the image member (1). To control the exposure focus (78), it is accurately positioned by considering the exposure focus,
A light device comprising at least one positioning bar (70). 11. The positioning bar (70) comprises a support housing (56) and a focusing device (5) for adjusting the distance between the engaged imaging member (1) and the focusing device (54).
4. Adjustable with respect to 4).
The light device according to item 0. 12. A light device for using an image construction with a transparent base (3), said device being positioned to contact said base for exposing through said base. Claim 1 characterized by the above.
The light device according to item 0.