JPH02264971A - Image forming method - Google Patents

Abstract

PURPOSE:To increase copying efficiency and to simplify control by preventing generation of inefficient exposure by setting linear velocity of a latent image carrier in a monochrome mode to be faster than linear velocity in a color, editing, or color erasing copying mode. CONSTITUTION:The device is constituted so that the following control is carried out by CPU through an operating part. When linear velocity of a photosensitive body 18, electrifying quantity to the photosensitive body 18, and impressing bias voltage to a developing roller are made constant, light emitting quantity of an illuminating device 11 is made larger in the image formation where a color dissolving filter is utilized than when it is not utilized. Further, when linear velocity, exposing quantity, and the bias voltage are made constant, the electrifying quantity is lowered when the filter is utilized than when it is not utilized. Further, when the linear velocity, the light emitting quantity, and the electrifying quantity are made constant, the bias voltage is raised when the filter is utilized than when it is not utilized, and even when the potential of a base surface is rather high due to inefficient exposure, toner is prevented from adhering there. Thus inefficient exposure quantity is prevented, the copying efficiency can be increased, and further, the control can be simplified.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to electrostatic charging by projecting a light image passed through a color separation filter onto a latent image carrier that is rotationally driven and charged to a predetermined polarity. In the color copy mode, a latent image is formed, the latent image is visualized with color toner, and transferred to a transfer material.
A black-and-white copy that forms an electrostatic latent image by projecting a light image through a D filter or no filter at all, visualizes the latent image with black toner, and transfers it to a transfer material. A light image passed through a color separation filter is projected onto a latent image carrier which is rotated and charged to a predetermined polarity to form an electrostatic latent image with a portion omitted.

The latent image is visualized with color toner, transferred to a transfer material, and then passed through an ND filter or no filter at all on a latent image carrier that is driven once and charged to a predetermined polarity. A light image is formed and projected to form an electrostatic latent image corresponding to the part, the latent image is made visible with black toner, and the visible image obtained with color toner is transferred. Transfer the visible image of black toner obtained by an electrostatic latent image corresponding to the part onto the transfer material, and remove the part from the transfer material. The editing copy mode transfers a visible colored toner image obtained from an electrostatic latent image, and the optical image that passes through a color separation filter is formed on a latent image carrier that is rotated and charged to a predetermined polarity. The present invention relates to an image forming method capable of selecting each copy mode including an achromatic copy mode in which an electrostatic latent image is formed by projection, the latent image is visualized with black toner, and this is transferred to a transfer material.

[Prior Art and Problems to be Solved by the Invention] The above-mentioned image forming method employed in electronic copying machines, printers, facsimile machines, etc. has been conventionally known.

In this type of image forming method, first, the surface of a latent image carrier that is rotationally driven is uniformly charged to a predetermined polarity, a light image is formed and projected onto the surface, and the surface potential of the latent image carrier is selected. An electrostatic latent image is formed by dropping the latent image, and in this case, in order to increase copying efficiency, it is desirable to increase the linear speed of the latent image carrier as much as possible.

On the other hand, when forming an electrostatic latent image, a sufficient amount of light is applied to the area that should become the background area of the latent image, and the surface potential is sufficiently lowered to prevent toner from adhering there during development. There is a need. However, in order to increase copy efficiency,
If the linear speed of the latent image carrier is made too fast, the amount of exposure to the latent image carrier will be too low, and the amount of exposure to the background area will be insufficient, and toner will adhere there during development, causing background smearing. There is a fear.

In particular, when executing the color copy mode or the achromatic copy mode, an optical image that has passed through a color separation filter with a small amount of transmitted light is projected onto the surface of the latent image carrier.

Insufficient exposure to the surface of the latent image carrier is likely to occur. For this reason, the latent image carrier is rotated relatively slowly.

There is no choice but to irradiate a sufficient amount of light onto the area that should become the skin.

On the other hand, as in the black-and-white copy mode, the light image is projected onto the latent image carrier without passing through a color separation filter, instead passing through an ND filter that transmits a large amount of light, or without passing through a filter at all. Because the amount of light is large, even if the latent image carrier is rotated at a relatively high speed, a sufficient amount of light is applied to the area that should become the background, and the surface potential is sufficiently reduced.
It is possible to prevent toner from adhering here.

As mentioned above, in the copy mode using a one-color separation filter, the linear speed of the latent image carrier is lowered, and conversely, in the copy mode using an ND filter or no filter at all, the linear speed of the latent image carrier is increased. It can be seen that it is advantageous to configure it as follows.

In this way, in the former copy mode, insufficient exposure to the latent image carrier can be prevented from occurring, and in the latter copy mode, copy efficiency can be increased without any problem.

By the way, the editing copy mode described at the beginning includes both a step using a color separation filter and a step not using such a filter but using either no filter or an ND filter. In such a case, in order to control the linear velocity of the latent image carrier according to the above idea, the linear velocity of the latent image carrier should be lowered during the former process using a color separation filter, and the linear velocity of the latent image carrier should be lowered during the latter process when a color separation filter is not used. It is only necessary to increase the linear speed of the latent image carrier during the process.

However, when performing individual editing copies that perform continuous operations,
If the linear velocity of the latent image carrier is configured to be switched, the control becomes very complicated and the cost of the apparatus increases.

The present invention has been made based on the above-mentioned novel recognition, and its purpose is to prevent the occurrence of insufficient exposure to the latent image carrier and to increase copying efficiency as much as possible. It is an object of the present invention to provide an image forming method of the type mentioned at the beginning, which can be performed easily and, moreover, the control can be simplified.

[Means to solve the problem]

In order to achieve the above object, the present invention makes the linear velocity of the latent image carrier in black and white copy mode higher than the linear velocity of the latent image carrier in color copy mode, editing copy mode, and achromatic copy mode. We propose a fast image forming method.

In addition, a color developer that visualizes an electrostatic latent image with colored toner, and a black developer that visualizes an electrostatic latent image with black toner, are connected to a developing roller that rotates while carrying developer. When the developing rollers are provided, it is advantageous to rotate these developing rollers at high speed when the linear velocity of the latent image carrier is high, and at low speed when the linear velocity of the latent image carrier is slow.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a color copying machine for carrying out the method according to the present invention. First, to explain its overall configuration, an illumination device 11 moves to the right in the figure together with the first mirror 12, illumination scanning of the original is performed. The scanning light image at this time is the second light image moving in the same direction.
The light enters the lens 15 via the mirror 13 and the third mirror 14, and is then reflected by the fourth mirror 16, and is transmitted to a plurality of color separation filters 17R, 17G, 17B and an ND filter 17N.
The image is projected onto a drum-shaped photoreceptor 18, which is an example of a latent image carrier. Filter tribe! 17 is each filter 17R, 170, 17
B and 17N are arranged radially and rotate together to bring any one filter into the optical path.

The photoreceptor 18 rotates clockwise in the figure, and the photoreceptor 1
The surface of 8 is uniformly charged to a predetermined polarity by a charger 19 prior to the image projection described above.

Therefore, an electrostatic latent image is formed on the surface of the photoreceptor 18 by the image projection.

Around the photoreceptor 18, color developers such as a yellow developer 21Y, a magenta developer 21M, and a cyan developer 21C are provided, as well as a black developer 21B.

When the color copy mode is selected by pressing the copy mode selection key (not shown) on the operation unit (Fig. 7) attached to the copying machine main body, the lens 1 is pressed as described above.
The light image passing through 5 passes through one of the color separation filters in the filter group W117, for example, the red filter 17R,
An optical image of the red component is extracted, which forms an electrostatic latent image on the photoreceptor surface, as previously described. This latent image is transferred to the cyan developing device 21, which is one of the color developing devices.
C, it is visualized with cyan toner.

A transfer paper, which is an example of a transfer material sent from a paper feed section 23, is wound around a transfer drum 22 that is placed opposite to the photoreceptor 18 and rotates counterclockwise. The visual image is transferred. The toner remaining on the photoreceptor 18 after the visible image transfer is removed by a cleaning device! 27, and neutralized by a static eliminator 33.

Next, the same document is illuminated and scanned again, and the light image from the document at this time passes through the green filter 17G provided in the optical path, and a green component light image is extracted. This light image is formed and projected onto the photoreceptor 18 in exactly the same manner as described above, and the electrostatic latent image obtained thereby is visualized with magenta toner of magenta developer WI21M. Ru. This visible image is also transferred to the transfer paper wrapped around the transfer drum 22 so as to be superimposed on the previous cyan visible image, and the photoreceptor 18 after the visible image transfer is transferred to the cleaning device! 27, the remaining toner is cleaned and static electricity is removed.

Similarly, a blue component optical image is extracted by the blue filter 17B, and this optical image is formed and projected onto the photoreceptor 18, and the electrostatic latent image thus obtained is yellow in the yellow developing device 21Y. This visible image is transferred to the transfer paper on the transfer drum 22 in a superimposed manner with the previous visible image, and the photoreceptor 18 after the visible image is transferred is cleaned by the cleaning device 27. It is cleaned and then neutralized.

After finishing the last transfer, transfer the transfer paper to the separate charger 2.
4 and separation claw 25 from the transfer drum 22,
The paper then passes through the fixing device 26 and is discharged outside the machine as full-color copy paper.

Next, when the black and white copy mode is selected by pressing the copy mode selection key, the image is reflected by the original and the lens 1
The light image passing through 5 passes through an ND filter (neutral density filter) 17N of a filter device 17,
An electrostatic latent image is formed on the photoreceptor 18 in exactly the same manner as in the color copy mode. The ND filter is a filter that basically passes all blue, red, and green component light. The latent image thus formed is visualized by black toner from the black developer 21B. This visible image is also transferred to the transfer paper on the transfer drum 22, and after this transfer, the transfer paper is removed from the transfer drum 22 and transferred to the fixing device 222.
, the transferred visible image is fixed onto the transfer paper. In this way, the transfer paper is discharged outside the machine as a copy paper of a black and white visible image. In this case as well, the surface of the photoreceptor after the visible image has been transferred is cleaned by the cleaning device fi27.

It is then energized.

Next, when the achromatic copy mode is selected by pressing the achromatic key (not shown) provided on the operation unit, the optical image obtained by illuminating and scanning the original as described above is
After passing through the lens 15 and being reflected by the mirror 16, any one color separation filter 17R, 1 selected by the operator is applied.
The image is projected onto the photoreceptor 18 through 7B or 17G.

When making a black and white copy from a color original, the achromatic copy mode erases any color image of the original before copying. For example, if you want to erase a red image in the original image, A red filter 17R is arranged in the optical path leading to the photoreceptor 18, and a light image passing through this filter 17R is projected onto the photoreceptor 18. Therefore, the charge on the surface of the photoreceptor corresponding to the red image of the original is substantially erased. More precisely, the surface potential is lowered to prevent toner from adhering to this portion.

The electrostatic latent image thus obtained is visualized with black toner from the black developer 21B. At this time, the above-mentioned surface area of the photoconductor corresponding to the red image of the original does not have a surface potential high enough for toner to adhere to it, so toner does not adhere there, and the image of other colors of the original image does not have enough surface potential to attract toner. Toner adheres to the corresponding photoreceptor surface area. The visible image is transferred to the transfer drum 22
The image is transferred to the upper transfer paper, and the photoreceptor after the transfer is subjected to cleaning and static neutralization. The transfer paper on which the visible image has been transferred is removed from the transfer drum 22 and passes through the fixing device 26, where the visible image is fixed. The red part of the image is missing. That is,
An achromatic copy image was obtained.

When deleting the green or blue image in the original image,
A green filter 17G or a blue filter 17B is provided in the optical path, and the light image passing therethrough is projected onto the photoreceptor, and the electrostatic latent image formed thereby is visualized by black toner to form a desired image. You will get a copy with no color.

Next, when the edit key on the operation unit is pressed, the edit copy mode is executed. In this copy mode, only the desired part of the color original image is reproduced as a black and white visible image, and the other parts are reproduced as color visible images to obtain copy paper. For example, the original shown in FIG. Of the color image, only the portion indicated by Dl is copied in black and white, and the remaining portion D2 is copied as a color image to obtain copy paper. In this case, the one-color separation filter 17R,
17G and 17B are used sequentially to obtain a color visible image transferred onto transfer paper, but the difference from the color copy mode is that each electrostatic latent image is transferred to developing devices 21C, 21M, and 2.
Before developing with 1Y, use the erase lamp 3 shown in Figure 1.
By 4.

The electrostatic latent image corresponding to the document image portion D1 shown in FIG. 2 is erased each time. As a result, an electrostatic latent image with a portion removed is obtained.

The erase lamp 34 is composed of, for example, a light emitting diode array having a large number of light emitting parts arranged in the axial direction of the photoreceptor 18, and when the electrostatic latent image portion formed corresponding to the document image portion D1 passes through the erase lamp 34, , the corresponding light-emitting section lights up to apply a charge-eliminating action to this electrostatic latent image area, thereby preventing it from being developed with toner. Therefore, in the visible image transferred to the transfer paper, the portion corresponding to the original image portion D1 is left blank.

Next, the same document is scanned with illumination again, but this time, the ND filter 17N of the filter device 17 is brought into the optical path as in the black-and-white copy mode, and the light image from the document passes through this filter 17N and is exposed to light. The image is projected onto the body 18, and an electrostatic latent image corresponding to the entire YK image is formed.

This latent image is transferred to the erase lamp 3 as the photoreceptor 18 rotates.
At this time, the electrostatic latent image corresponding to the image portion indicated by D2 of the original shown in FIG. 2 is erased by the erase lamp 34. Namely.

Only the electrostatic latent image corresponding to the document image portion indicated by Dl is left behind. In other words, when an electrostatic latent image was formed using a color separation filter, an electrostatic latent image with a part removed was obtained, but conversely, an electrostatic latent image corresponding to this part was obtained. A latent image is obtained. The electrostatic latent image thus obtained is processed by a black developing device 21B.

A visible image is created using black toner, and this visible image is transferred onto the transfer paper onto which the visible image previously obtained using color toner has been transferred. That is, a color visible image is formed,
A black-and-white visible image is transferred onto the transfer paper, which has some white spots.

The transfer paper onto which the visible image has been transferred in this manner is removed from the transfer drum 22, passes through the fixing device M26, and is discharged to the outside of the machine.

Contrary to what was described above, first obtain a black and white visible image corresponding to the Dl portion of the original, transfer this to transfer paper, and then
A color visible image corresponding to the second part may be obtained and transferred to the same transfer paper.

In addition, in the above-mentioned monochrome copy mode and edit copy mode, when forming the external electromagnetic latent image to be visualized with black toner, it is not passed through any filter, that is, the ND filter 17N is used.
Alternatively, the light image from the original may be directly projected onto the photoreceptor 18 without passing through the original.

Next, for understanding the present invention, each developing device 21Y, 21M, 2
The structure and operation of 1C and 21B will be explained.

First, the color developing devices 21Y, 21M, and 21G.

As shown in FIG. 3, a casing 3Y containing developer
, 3M, 3C, and developing rollers 4Y, 4M made of non-magnetic material and arranged close to the photoreceptor 18.

4C, and developer stirring and drawing members 7Y, 7M, and 7C placed opposite to these rollers. In this example, a two-component developer consisting of a magnetic carrier and toner is used as the developer. As can be seen from the explanation, yellow toner is used in the yellow developer 1121Y, magenta toner is used in the magenta developer 21M, and cyan toner is used in the cyan developer 21C. It is well known that additives are added to toners as necessary.

Inside each of the developing rollers 4Y, 4M, and 4G, a magnet group 5 is provided in the arrangement shown in the figure, and these are held in a non-rotating state. On the other hand, each of the developing rollers 4Y, 4M, and 4C is rotationally driven in the direction of the solid line arrow during the developing operation.

Here, as shown in FIG. 4, the magnet group 5, which is arranged inside the developing roller 4C to pick up the cyan developer 1121c, includes magnets 5a, 5b, and 5c arranged along the circumferential direction of the developing roller 4C.

5d, and the respective magnetic poles on the side facing the developing roller 4C are arranged as indicated by S and N in the figure.

Moreover, no magnet is provided between the magnets 5b and 5e,
A magnetic shorting plate 6 made of a soft magnetic member is bridged between these magnetic poles, and a magnetic field strength reduction region 113 is formed.

The configuration shown in FIG.
1M and 21Y have exactly the same configuration.

As explained above, when the color copy mode or the edit copy mode is selected, first the cyan developer 21C performs a developing operation, but at this time, the developing roller 4C rotates normally in the direction of the solid line arrow, and the aforementioned developer The stirring and pumping member 7C rotates counterclockwise to pump up the developer present at the bottom of the casing 3C to the developing roller 4C. The developer supplied to the developing roller 4C in this way is supported on the developing roller 4C by the magnetic force of the magnet group 5, and is conveyed in the rotation direction by the rotation of the developing roller 4C. The developer is scraped off and the amount of developer is regulated. In this way, the developer carried on the normally rotating developing roller 4C is carried to the opposing area between the developing roller 4C and the photoreceptor 18, where it is developed into the electrostatic latent image formed on the photoreceptor. The toner in the agent transfers electrostatically, turning this electrostatic latent image into a visible image. The developer used for development is further transported,
When reaching the magnetic field strength reduction region 113, the magnetic field in this region is weak, so the developer on the developing roller 4C falls downward under its own weight and is stirred by the developer stirring and pumping member 7C.

The magenta developing device $21M and the yellow developing device 21Y also visualize the electrostatic latent image using the toner of each color in exactly the same manner.

Note that when one developing device finishes its developing operation, the developer on that developing roller is removed, and unnecessary parts are removed from the visible image or electrostatic latent image formed by the next developing device. It is configured to prevent toner from adhering. This developer removal operation is generally referred to as the ear cutting operation. For example,
When the cyan developing device 21C finishes its developing operation, its developing roller 4C is driven to rotate in the direction of the dashed arrow, which is opposite to the rotational direction up to that point. During this rotation, the magnetic field strength reduction area 113 is
, the TIL developer is transferred to the developing roller 4. The developer that has not been pumped up by the developing roller 4C and has been carried on the developing roller 4C until then is transported in the same direction as the rotating direction of the developing roller 4C, and falls downward from the developing roller 4C under its own weight. . After the ear cutting operation is completed, the developing roller 4C stops.

The magenta developing device 21M continues to perform the developing operation, but even after that operation, the cutting operation is performed in exactly the same manner as described above, the developing roller 4M stops, and the yellow developing device 21Y then performs the developing operation. Also, after the operation is completed, the ear cutting operation is performed, and then the developing roller 4Y
stops.

Next, the black developing device 21B will be explained with reference to FIG. 5. This developing device 21B also contains a two-component developer consisting of black toner and magnetic carrier to which additives are added as necessary. It has a casing 3B, a developing roller 4B made of a non-magnetic material and placed opposite to the photoreceptor 18, and a developer stirring and pumping member 7B. Inside the developing roller 4B, there is a magnet group 5B consisting of magnets labeled Pl to P5.
.

is fixedly placed.

During the black developing process in the black and white copy mode, achromatic copy mode, or edit copy mode, the developing roller 4B and the developer stirring and pumping member 7B are rotated counterclockwise in FIG. 4, and the developer is deposited on the developing roller 4B. is supplied. The supplied developer is supported on the developing roller 4B by the magnetic force of the magnet group 5B, and is conveyed in the same direction as the rotation direction by the rotation of the roller 4B, and is transferred to the doctor part 12B.
After regulating the developer amount, the photoreceptor 18 and the developing roller 4
The black toner in the developer transfers to the electrostatic latent image and makes the latent image visible.

At this time, magnet P2. A soft magnetic member 37 occupies the position shown by the solid line so as to cover the area between P3, and the strength of the magnetic field on the surface of the developing roller facing the soft magnetic member 37 is weakened. Therefore, when the developer used for development reaches this area, the developer separates from the developing roller 4B due to its own weight and falls downward.

When the mode is switched from black and white copy mode to color copy mode, or during the color image forming process in edit copy mode, the soft magnetic member 37 moves to the position shown by the chain line in FIG. 5, and the developer is transferred to the developing roller 4B. The developer on the developing roller 4B is removed as the roller 4B rotates. In other words, the ear cutting operation is performed.

As described above, in the copying machine shown in FIG. 1, it is possible to select a color copy mode, a monochrome copy mode, an editing copy mode, or an achromatic copy mode to obtain copy paper with various types of images.

When executing such a copy mode, as described above, the faster the linear velocity, that is, the circumferential velocity, of the photoreceptor 18, the faster the
The copy efficiency can be improved. However, like in color copy mode or achromatic copy mode,
During an image forming operation using a color separation filter, since the amount of light transmitted through this filter is small, the amount of light reaching the surface of the photoreceptor 18 is reduced. Therefore, in such a case, if the linear velocity of the photoreceptor 18 is increased too much, the surface of the photoreceptor 18 becomes the background area, that is, the area where the surface potential should be lowered to prevent toner from adhering.

Due to the exposure accompanying the projection of the optical image, it becomes impossible to provide a sufficient static elimination effect. If the surface potential of the background portion cannot be lowered sufficiently, toner will adhere there during development and background smear will occur. There is a method of increasing the amount of light emitted by the illumination device 11 shown in FIG. It is not possible to cope with the insufficient exposure amount when rotating the photoreceptor 18 at high speed.For this reason, the linear speed of the photoreceptor cannot be increased much during a copy mode using a color separation filter.

On the other hand, when a light image is formed and projected onto the photoreceptor 18 without using a single color separation filter, such as in the black and white copy mode, a large amount of light can be irradiated onto the photoreceptor 18, so the linear speed of the photoreceptor 18 is Even if the speed is fast, a sufficient amount of light can be applied to the surface area, which lowers the surface potential and prevents the occurrence of background stains.

Therefore, in the present invention, from the above-mentioned viewpoint, the linear speed of the photoreceptor 18 in the monochrome copy mode is set to be faster than the linear speed of the photoreceptor 18 in the color copy mode. Similarly, the slow speed of the photoconductor 18 in the black-and-white copy mode is set higher than the linear speed of the photoconductor 18 in the one-color erase copy mode.

If the linear speed of the photoreceptor 18 is set in this way, the photoreceptor 18 will rotate at a low speed when executing the color copy mode and color printing copy mode that use one-color separation filters, so that the area that should be the background will be By irradiating a sufficient amount of light, the surface potential can be lowered sufficiently.

It is possible to prevent the occurrence of scumming. On the other hand, in the black-and-white copy mode, the photoreceptor 18 can be rotated at high speed to improve copy efficiency.

The next problem is that the photoconductor 18 in the edit copy mode
When in edit copy mode, the linear speed is 0.

forming an electrostatic latent image using a color separation filter;
The process of forming an electrostatic latent image using the D filter 17N (or without the filter) is performed continuously. Therefore, in this case, when using the ND filter 17N as in the latter case, compared to when using the color separation filter as in the former case,
By increasing the linear velocity of the photoreceptor 18, insufficient light quantity can be prevented.

Moreover, copying efficiency can be improved, so it can be said to be ideal. However, these edit copy modes are normally performed continuously without stopping the photoreceptor 18, so if the linear speed of the photoreceptor 18 is changed when executing each edit copy mode, the control becomes very complicated.

Therefore, in the present invention, in Collection II Copy Mode 1, Photoreceptor 1
In addition, the linear speed of the photoreceptor in this copy mode is set to be slower than the linear speed of the photoreceptor in the black-and-white copy mode. With this configuration, the linear velocity of the photoreceptor 18 can be kept constant during execution of the edit copy mode, and its control becomes simple. Moreover, it is possible to maintain the linear velocity of the photoreceptor 18 constant during the execution of the editing copy mode, and moreover, during the process of forming an electrostatic latent image using a color separation filter. Also, the amount of exposure is insufficient,
It is possible to prevent the problem of background stains.

The linear velocity of the photoreceptor 18 is also relatively slow during the process of forming an electrostatic latent image using the ND filter 17N, but even if this is done, the copying efficiency will decrease to some extent.
There is no problem in forming an electrostatic latent image, and background stains can be reliably prevented.

In addition to the above-mentioned copy modes, the copying machine shown in the figure also has one color developing device 21Y.

21M and 21C can also be used to select a single copy mode in which a monochrome visible image is obtained. Similar to the black and white copy mode, this copy mode forms an electrostatic latent image on the photoreceptor 18 without using a color separation filter, and transfers this to one of the color developers 21Y and 21M selected by the operator. Or 21G is used to visualize the image, which is then transferred to transfer paper and fixed. In this way, since a single color separation filter is not used even in the single color copy mode, a large amount of light can be irradiated onto the photoreceptor 18 when forming a latent image.
Even if the line speed of 8 is increased, scumming can be prevented. Therefore, the linear speed of the photoconductor in this single color copy mode should be set faster than the linear speed of the photoconductor in the color copy mode, edit copy mode, and achromatic copy mode, just as in the monochrome copy mode. is desirable.

By the way, in this example, as explained earlier, each developing device 21Y
, 21M, 21G, and 2P1B, developing rollers 4Y and 4M rotate while carrying developer.

4G and 4B are used, but when the linear velocity of the photoconductor 18 is high, the Tyt image roller is rotated at high speed in order to increase the amount of toner supplied per unit time to the electrostatic latent image on the surface. It is necessary to do so. This is because if the amount of toner supplied to the electrostatic latent image is small, the quality of the visible image deteriorates. On the other hand, when the linear speed of the photoreceptor 18 is slow, the number of revolutions of the developing roller may be lowered.From this viewpoint, in the present invention, in the monochrome copy mode where the linear speed of the photoreceptor 18 is fast, the developing roller is lowered. The rotation speed of the developing roller 4B is increased, and the rotation speed of the developing roller is lowered during color copy mode, editing copy mode, and achromatic copy mode in which the linear speed of the photoreceptor 18 is slow. In this way, the quality of the visible image can be maintained at a high quality regardless of the linear velocity of the photoreceptor 18.

Here, to give an example, the photoreceptor 18 in black and white copy mode
．． The linear speed of the photoreceptor 18 is set to 226 m/see, and the rotational speed of the developing roller 4B is set to 270 rpm. The rotation speed of the developing roller is set to 113 rpm/see and 135 rpm. The numerical values shown here take into consideration that the amount of exposure to the photoreceptor 18 changes depending on the amount of light emitted from the illumination device W111 shown in FIG.
9 shows the results when the amount of light emitted is changed according to each copy mode. In addition, in the numerical example above, the number of rotations of the developing roller in the color copy mode, edit copy mode, and achromatic copy mode are all 135 rp@, but the photoreceptor 18 due to the charger 19 shown in FIG. The rotation speed of the developing roller 4B in the stiff copy mode may be changed depending on the difference in the amount of charge on the image forming apparatus.For example, the rotation speed of the developing roller 4B in the edit copy mode may be set to 135 rp, and the rotation speed of the developing roller 4B in the achromatic copy mode may be changed to 135 rpm. The number of rotations of the same roller 4B is 22
It can also be set to 5RP.

By the way, as can be seen from the above explanation, in order to compensate for the decrease in the amount of exposure to the photoreceptor 18 when forming a latent image using a color separation filter, in addition to changing the linear speed of the photoreceptor 18, the illumination device 11 can be adjusted. It is desirable to change the amount of light emitted and the amount of charge on the photoreceptor 18 by the charger 19, and each developer 21Y,
Developing rollers 4Y and 4M in 21M, 21G, and 21B
, 4C.

4B, a bias voltage is applied as is known in the art to make it difficult for toner to adhere to the background portion of the electrostatic latent image on the photoconductor 18 and prevent background smearing, but this bias voltage also affects color separation. It is desirable to change the time when a filter is used and when it is not used.

To give a specific example, the linear velocity of the photoreceptor 18 is constant, the charger 19
Assuming that the amount of charge on the photoconductor 18 is constant and the bias voltage applied to the developing roller is constant, when forming an image using a color separation filter, the amount of light emitted by the illumination device 11 is increased compared to when the color separation filter is not used. , to compensate for insufficient exposure to the photoreceptor 18.

Furthermore, assuming that the linear velocity of the photoreceptor 18 is constant, the amount of light emitted by the illumination device 11 is constant, and the bias voltage applied to the developing roller is constant, when forming an image using a color separation filter, the charger is To reduce the amount of charge on the photoreceptor 18 caused by the photoreceptor 19.

In this way, at least the amount of light during exposure can sufficiently reduce the surface potential of the background portion of the electrostatic latent image.

Further, when the linear velocity of the photoconductor 18 is constant, the amount of light emitted by the illumination device 1111 is constant, and the amount of charge on the photoconductor 18 by the charger 19 is constant, when forming an image using a color separation filter, when not using it, compared.

The bias voltage applied to the developing roller is increased to prevent toner from adhering to the background area even if the potential of the background area becomes high due to insufficient exposure.

In reality, the linear velocity of the photoreceptor 18, the amount of charge on the photoreceptor 18,
Lighting equipment! ! It goes without saying that each value of the amount of light emitted in 11 and the bias voltage applied to the developing roller should be set comprehensively to suit each copy mode.

FIGS. 6(a), (b), and (c) show the operation flow of the copying machine associated with selection of each copy mode. FIG. 7 is a block diagram thereof.

The present invention can also be applied when a one-component developer containing no carrier or a non-magnetic developer is used in each developing device.

〔Effect of the invention〕

According to the configuration described in claim 1, it is possible to prevent insufficient exposure to the latent image carrier, increase copying efficiency, and also achieve simplification of control.

According to the configuration described in claim 2, even if the linear velocity of the latent image carrier changes, the quality of the visible image can always be maintained at high quality.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a color copying machine that implements the method according to the present invention, FIG. 2 is an explanatory diagram showing a document to be copied in edit copy mode, and FIG. An enlarged view of the color developing device, FIG. 4 is a partially enlarged view of the same, FIG. 5 is an enlarged view of the black developing device, and FIG.
) and (c) are flowcharts showing operations corresponding to each copy mode, and FIG. 7 is a block diagram thereof. 4Y, 4M, 4C, 4B...Developing rollers 17R, 17
B, 17G... Color separation filter 17N... ND filter 21Y, 21M, 21C, 21B... Developer agent
Patent Attorney Norio Hoshino Figure 6 ('t)) Figure 6 CC)

Claims (2)

[Claims] (1) An electrostatic latent image is formed by projecting a light image passed through a color separation filter onto a latent image carrier that is rotationally driven and charged to a predetermined polarity, and the latent image is painted with color toner. A color copy mode that visualizes the image and transfers it to a transfer material, and a latent image carrier that is rotated and charged to a predetermined polarity.
A black-and-white copy mode in which an electrostatic latent image is formed by projecting a light image through an ND filter or no filter at all, and the latent image is made visible with black toner and transferred to a transfer material. and a latent image carrier that is rotationally driven and charged to a predetermined polarity,
A light image passed through a color separation filter is projected to form an electrostatic latent image with a portion removed, and the latent image is made into a visible image with colored toner and transferred to a transfer material, and then After that, an electrostatic latent image corresponding to the part is formed by projecting a light image onto a latent image carrier that is rotationally driven and charged to a predetermined polarity through an ND filter or without passing through a filter at all. Then, the latent image is made visible with black toner, and this is transferred onto the transfer material on which the visible image obtained with color toner has been transferred, or an electrostatic latent image corresponding to the part is transferred. an editing copy mode in which a visible image of black toner obtained by the image is transferred to a transfer material, and a visible image of color toner obtained by the electrostatic latent image with the part removed is transferred thereon; , a latent image carrier that is rotationally driven and charged to a predetermined polarity,
Each copy mode includes an achromatic copy mode in which a light image passed through a color separation filter is projected to form an electrostatic latent image, which is visualized with black toner and transferred to a transfer material. An image forming method in which the linear speed of the latent image carrier in black-and-white copy mode is higher than the linear velocity of the latent image carrier in color copy mode, editing copy mode, and achromatic copy mode. Image forming method set quickly. (2) A color developer that visualizes an electrostatic latent image with color toner, and a black developer that visualizes an electrostatic latent image with black toner, which rotate while carrying developer. 2. The image forming method according to claim 1, wherein the developing rollers are rotatably driven at high speed when the linear speed of the latent image carrier is high and at low speed when the linear speed of the latent image carrier is slow. .