JP2005165360A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preferentially performing the prevention of reverse transfer and the shortening of copying time in accordance with user's requests as to an image forming apparatus comprising a developing device capable of developing an image by developers of a plurality of colors including black and capable of finally transferring developed images of respective colors which are visualized on an image carrier by the developers of the developing device to a transfer material. <P>SOLUTION: Image forming order by a black developer in a Bk developing unit 14 can be switched in accordance with copying modes included in the image forming apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that uses electrophotography such as a copying machine, a printer, and a facsimile machine that processes image data as a digital signal.

  In a color image forming apparatus which is one of image forming apparatuses, when a color image is created, toner images of three primary colors (cyan, magenta, yellow) of subtractive color mixing are formed on a transfer sheet.

  In digital image forming apparatuses that have been rapidly widespread in recent years, it is possible to process a document as a color-separated digital signal, so that black portions such as characters can be reproduced only with black toner as a developer. Therefore, for reproduction of a general color document, image formation is performed using black, cyan, magenta, and yellow developers.

  In addition, a method of scanning a document once before scanning for determining the color of the document, and a method of performing determination and performing image formation at the same time as scanning in order to increase the copying speed have been put into practical use in recent years. .

  In digital image forming apparatuses, as an output medium for image data, in addition to a scanner as a copying machine, a medium such as a computer or a facsimile is beginning to be put into practical use by using a controller.

It has a developing device that can be visualized with a developer of multiple colors including black, and finally the visualized image of each color visualized with the developer of the developing device on the image carrier is used for transfer paper and overhead projector. An image forming apparatus for transferring to a transfer material such as paper, and as a multiple transfer system of a typical full color image forming apparatus,
(B) Direct transfer system that mechanically and electrostatically fixes the transfer paper to the dielectric sheet and belt, and sequentially transfers the toner images of each color formed on the photoconductor (b) Medium resistance resin and rubber There is an intermediate transfer system in which toner images of respective colors formed on a photoreceptor are sequentially transferred to a belt / roller as an intermediate transfer medium formed in this manner, and finally all images are collectively transferred to a transfer agent.
A common problem with these transfer systems is that the toner image is transferred directly from the image carrier, such as a photoconductor, to the final transfer material, or the image is transferred from the image carrier to the intermediate transfer material once. In addition, when following the process of transferring from the intermediate transfer material to the final transfer material, if images are created at different locations for each color during the transfer process from the image carrier, the first visible image is displayed. When the image is transferred from the carrier to the transfer material and then another image is transferred from the image carrier to the transfer material, the first visible image already transferred onto the transfer material is reversed on the image carrier. There is a problem of being copied. This reverse transfer is likely to occur in the subsequent transfer process where no other color is transferred to the same location.

  In a full-color image, colors are reproduced by overlapping colors at the same location. Therefore, transfer of secondary colors and tertiary colors performed after the first transfer is sequentially performed at the same location. For this reason, reverse transfer from the transfer material to the image carrier is unlikely to occur.

  In the case where the color image and the black character image exist in different locations in the same image, this case is also a kind of full color image, but in such a full color image, in the black character portion reproduced only with black toner, Since there is no secondary color or tertiary color, it is most susceptible to reverse transfer. The amount of toner transferred onto the final transfer material is reduced and the density is reduced by the amount of reverse transfer. This causes problems such as difficulty in reading and degradation of image quality.

In an apparatus using a method of performing black part determination and image formation at the same time as the scan described above, black part image formation is performed first, and when it is determined that the original is a color document, color image image transfer is performed thereafter. In particular, reverse transfer becomes a problem.
On the other hand, there is a technique for forming an image in the order of Y, M, C, and Bk (see, for example, Patent Document 1). According to this technique, since the black image is formed last, the problem of reverse transfer does not occur as a result.

Japanese Patent Laid-Open No. 4-69677

  In the known technique, as a premise of this technique, it is impossible to determine whether the image is a color image or a black and white image unless scanning is completed once. For this reason, pre-scanning is performed. In the pre-scan, it is determined whether the original is color or black and white from the ratio of each color data when the original is color-separated.

  In the case of automatic color selection, a pre-scan is performed to determine whether a color original or a black original. Then, the black image is created last in the case of a color original, and the black image is created from the beginning in the case of a black original.

  However, if only such a mode can be executed, any document, whether color or black and white, will be pre-scanned, and an original that does not require pre-scan, such as a black-image original, will be used. In the case of image formation, reverse transfer does not occur even if a black image is created from the beginning. Therefore, if automatic selection is not performed, pre-scanning is not necessary, and the time for this pre-scan is lost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can give priority to prevention of reverse transfer and priority to shorten copy time as required by a user.

In order to achieve the above object, the present invention is configured as follows.
(1) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally developing the visualized images of the respective colors visualized with the developer of the developing device on the image carrier as a transfer material In the image forming apparatus to be transferred, the image forming order by the black developer can be changed according to the copy mode of the image forming apparatus.

(2) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visualized image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. In the image forming apparatus to be transferred, the image forming order with at least the black developer has a copy mode that is the first with respect to the image forming order with the developer of the other color, and a copy mode that is the first or subsequent copy mode. (Claim 2).

(3) Having a developing device that can be visualized with a plurality of colors of developer including black, and finally developing the visible images of each color visualized with the developer of the developing device on the image carrier as a transfer material In the image forming apparatus to be transferred, the image forming order by at least the black developer has the first copying mode and the last copying mode with respect to the image forming order by the other color developer (claim). Item 3).

(4) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visualized image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. The image forming apparatus to be transferred has a copy mode in which image formation must first be performed with a black developer and a copy mode in which image formation may not be performed first with a black developer. Therefore, the order of image formation by the black developer is changed (claim 4).

(5) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visualized image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. In the image forming apparatus to be transferred, the image forming apparatus has a first copy mode in which image formation with a black developer must be first, and a second copy mode in which image formation with a black developer need not be first, When the first copying mode is selected, the image formation with black developer is first, and when the second image forming mode is selected, the black image forming order is set to be the first and following. (Claim 5).

(6) A developing device that can be visualized with a developer of a plurality of colors including black, and a visible image of each color visualized with the developer of the developing device on the image carrier is finally used as a transfer material. In the image forming apparatus to be transferred, the image forming apparatus has a first copy mode in which image formation with a black developer must be first, and a second copy mode in which image formation with a black developer need not be first, When the first copying mode is selected, the image formation with the black developer is first, and when the second image forming mode is selected, the black image forming order is the last. Item 6).

(7) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, a visible image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. The image forming apparatus to be transferred has a copy mode in which image formation with a black developer must be performed first, and a copy mode in which image formation with a black developer need not be performed first, and which mode is selected. Standard or selectable is selected, and the order of image formation with the black developer is changed in accordance with the selected copying mode.

(8) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visualized image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. In the image forming apparatus to be transferred, the order of image formation with the black developer is changed in accordance with the output medium of the image data.
(9) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visible images of each color visualized with the developer of the developing device on the image carrier are used as transfer materials. In the image forming apparatus to be transferred, when the image data is based on an output medium that must first be imaged by a black developer, the black image forming order is changed to the image forming order by another color developer. On the other hand, if the output medium does not have to be the first image forming with the black developer, the image forming order with the black developer is set to the first and following (claim 9). .

(10) Having a developing device that can be visualized with a developer of a plurality of colors including black, and finally, the visualized image of each color visualized with the developer of the developing device on the image carrier is used as a transfer material. In the image forming apparatus to be transferred, when the image data is based on an output medium that must first be imaged by a black developer, the black image forming order is changed to the image forming order by another color developer. On the other hand, when the image formation with the black developer is performed with the output medium which does not need to be performed first, the image formation sequence with the black developer is performed last (claim 10).

(11) Having a developing device that can be visualized with a plurality of colors of developer including black, and finally, each color visualized with the developer of the developing device is used as a transfer material on the image carrier. In the image forming apparatus to be transferred, the image forming order with the black developer is changed in accordance with the copy mode and the output medium of the image data.
Operation Based on the prescan result, the pre-scan is premised, and the mode in which the black image is not formed first and the mode in which the pre-scan is not performed and the processing speed is given priority are widened.

  According to the present invention, it is possible to provide an image forming apparatus in which priority can be given to prevention of reverse transfer and priority can be given to shortening of copy time as required by the user.

(one). Hereinafter, embodiments of the present invention will be described. FIG. 1 is a configuration diagram of a color copying machine according to the present invention, and FIG. 2 is an enlarged view around a photosensitive member as an image carrier and an intermediate transfer belt as a transfer material shown in FIG. The configuration and operation of this apparatus will be described below.

  The color copying machine has a color image reading device (hereinafter referred to as a color scanner) 1 and a color image recording device (hereinafter referred to as a color printer) 2 forming a printer unit.

  Hereinafter, description will be made with reference to FIGS. 1 and 2 as appropriate. The color scanner 1 forms an image of an original 3 on a color sensor 7 through an illumination lamp 4, mirrors 5-1, 5-2, 5-3, and a lens 6, and the color of the original. For example, image information is read for each color separation light of blue, green, and red, and converted into an electrical image signal. These decomposed lights are expressed as B, G, and R for convenience in the following description.

  Then, based on the B, G, and R color separation image signal intensity levels obtained by the color scanner 1, color conversion processing is performed by an image processing unit (not shown), and black (hereinafter referred to as Bk), Color image data of cyan (same as C), magenta (same as M), and yellow (same as Y) are obtained.

  This is visualized by using the Bk, C, M, and Y toners by the color printer 2 described below, and these toner images are superimposed to form a four-color full-color image.

  The operation method of the color scanner 1 for obtaining the image data of Bk, C, M, and Y is the illumination / mirror optical system shown in FIG. 1 in response to the scanner start signal that takes the operation and timing of the color printer 2. Scans the document in the direction of the left arrow and obtains one color image data for each scan.

  By repeating this operation four times, sequential four-color image data is obtained. Each time, the color printer 2 sequentially visualizes the images and superimposes them to obtain a four-color full-color image.

Next, an outline of the color printer 2 will be described.
The writing optical unit 8 converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on a drum-shaped photoconductor 9 as an image carrier. To do. In this latent image formation, the laser beam from the laser light source 8-1 is scanned through the polygon mirror 8-2 rotated by the drive motor 8-3, and the photosensitive member is detected by the fθ lens 8-4 and the reflecting mirror 8-5. It is formed by guiding the scanning light to 9.

  The photosensitive member 9 rotates counterclockwise as indicated by an arrow. Around the photosensitive member 9, a photosensitive member cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12, a potential sensor 13, and a BK developing unit 14 are provided. , C developing device 15, M developing device 16, Y developing device 17, development density pattern detector 180, intermediate transfer belt 19, and other devices for performing an electrophotographic copying process are arranged.

  In FIG. 2, each developing device includes a developing sleeve (14-1, 15-1, 16-1, and 17-1) that rotates so that the developer faces the photoconductor 9 in order to develop the electrostatic latent image. , Developer paddles (14-2, 15-2, 16-2, 17-2) that rotate to pump up and stir the developer, and toner concentration detection sensors (14-3, 15-3, 16-) of the developer 3, 17-3).

  In the standby state, the developer on each of the developing sleeves is in the ear cutting (development inactive) state for all four developing devices. The toner image formed on the photosensitive member 9 is transferred to the surface of the intermediate transfer belt 19 that is driven at the same speed as the photosensitive member (hereinafter, toner image transfer from the photosensitive member to the intermediate transfer belt is referred to as belt transfer). ).

  The belt transfer is performed by applying a predetermined bias voltage to the transfer bias roller 20 while the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other. On the intermediate transfer belt 19, the toner images of the respective colors sequentially formed on the photoreceptor 9 are sequentially aligned on the same surface to form a four-color superimposed belt transfer image, and then batch transfer onto the transfer paper. Do.

  Next, the intermediate transfer belt unit will be described. The intermediate transfer belt 19 is stretched around a drive roller 21, a belt transfer bias roller 20 and a driven roller group, and is driven and controlled by a stepping motor (not shown) connected to the drive roller 21.

  As shown in FIG. 2, the belt cleaning unit 22 includes a brush roller 22-1, a rubber blade 22-2, a contact / separation mechanism 22-3 from the belt, and the like. After the second, third, and fourth colors are transferred on the belt, the contact / separation mechanism 22-3 can be separated from the belt surface.

  The paper transfer unit 23 includes a paper transfer bias roller 23-1, a roller cleaning blade 23-2, a contact / separation mechanism 23-3 from the belt, and the like.

  The paper transfer bias roller 23-1 is usually separated from the surface of the intermediate transfer belt 19. However, when the four color superimposed images formed on the surface of the intermediate transfer belt 19 are collectively transferred to the transfer paper, timing is taken. The toner image is transferred onto the paper while being pressed by the contact / separation mechanism 23-3 and a predetermined bias voltage is applied by the paper transfer bias roller 23-1.

  As shown in FIG. 1, the transfer paper 24 is fed by a paper feed roller 25 and a registration roller 26 in accordance with the timing when the leading end of the four-color superimposed image on the intermediate transfer belt surface reaches the paper transfer position. The

  The intermediate transfer belt 19 can be moved in the following three ways as the operation method after the transfer of the first color BK toner image to the rear end portion. Or a combination of efficient methods (in terms of copy speed etc.) depending on the copy size.

(1) Constant-speed forward movement method (a) Even after the first color toner image is transferred to the belt, the forward movement is continued at a constant speed.

(B) When the leading edge position of the first color image on the surface of the intermediate transfer belt 19 reaches the belt transfer position at the contact portion with the photosensitive member 9 again, the photosensitive member 9 side is the leading edge of the next second color toner image. The image is formed at the timing so that the portion is exactly at that position.

  As a result, the second color image is accurately aligned with the first color image, and is transferred onto the intermediate transfer belt 19 while being transferred onto the belt.

(C) Thereafter, the same operation is followed to proceed to the third and fourth color image process, and a four-color superimposed belt transfer image is obtained.

(2) The toner image of the fourth color is continuously transferred to the transfer paper 24 as described above while moving forward as it is, following the toner image belt transfer process.

(2) Skip forward method (a) When the belt transfer of the first color toner image is completed, the intermediate transfer belt 19 is separated from the surface of the photoconductor 9 and is skipped at a high speed in the forward direction as it is, and when it moves a predetermined amount, Return to the forward speed. Thereafter, the intermediate transfer belt 19 is brought into contact with the photosensitive member 9 again.

(B) When the leading edge position of the first color image on the surface of the intermediate transfer belt 19 reaches the belt transfer position again, the leading edge portion of the next second color toner image is exactly at that position on the photosensitive member 9 side. As described above, images are formed at the timing. As a result, the second-color toner image is accurately aligned with the first-color toner image and transferred onto the belt in a superimposed manner.

(C) Thereafter, the same operation is followed to proceed to the third and fourth color image process to obtain a four-color superimposed belt transfer image.

(2) Following the fourth color toner image belt transfer step, the four color superimposed toner images on the surface of the intermediate transfer belt 19 are collectively transferred onto the transfer paper 24 at the same forward speed.

(3) Reciprocating (quick return) method (a) When the belt transfer of the first color toner image is completed, the intermediate transfer belt 19 is separated from the surface of the photosensitive member 9, and the forward movement is stopped and at the same time the high speed return is performed in the reverse direction. Let In the return, the front end position of the BK image on the surface of the intermediate transfer belt 19 passes through the belt transfer equivalent position in the reverse direction, and further, after moving a preset distance, is stopped and put into a standby state.

(B) Next, when the leading end of the second color toner image on the photoconductor 9 side reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is again started in the forward movement direction. Further, the intermediate transfer belt 19 is brought into contact with the surface of the photoreceptor 9 again. In this case as well, the belt transfer is performed under the condition that the second color toner image accurately overlaps the first color toner image on the surface of the intermediate transfer belt 19.

(C) Thereafter, the same operation is followed to proceed to the third and fourth color toner image processes to obtain a four-color superimposed belt transfer image.

(2) Following the belt transfer process of the toner image of the fourth color, the four-color superimposed toner image on the surface of the intermediate transfer belt 19 is collectively transferred to the transfer paper 24 without moving back at the same speed.

  Now, the transfer paper 24 onto which the four-color superimposed toner images have been collectively transferred from the intermediate transfer belt surface is conveyed to a fixing device 28 by a paper conveying unit 27 in FIG. 1, and a fixing roller 28-1 controlled to a predetermined temperature. The toner image is melted and fixed by the pressure roller 28-2 and carried to the copy tray 29 to obtain a full color copy.

  The surface of the photoreceptor 9 after the belt transfer is cleaned by a photoreceptor cleaning unit 10 (pre-cleaning static eliminator 10-1, brush roller 10-2, rubber blade 10-3), and uniform by a static elimination lamp 11. To be neutralized.

  Furthermore, the surface of the intermediate transfer belt 19 after the toner image is transferred to the transfer paper 24 is cleaned by pressing the cleaning unit 22 again with the contact / separation mechanism 22-3.

  In the intermediate transfer belt 19, the second toner image is belt-transferred to the area where the surface is cleaned by the cleaning unit 22 following the batch transfer process of the first four-color superimposed image to the transfer paper. So that After that, the operation is the same as the first sheet.

  In FIG. 1, transfer paper cassettes 30, 31, 32, and 33 store transfer papers of various sizes, and register with timing from the size paper storage cassette designated on the operation panel (not shown). Paper is fed and conveyed in the direction of the roller 26. Reference numeral 34 denotes a manual paper feed tray such as OHP paper or cardboard.

  The copy mode for obtaining four full colors has been described above. However, in the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times.

  In the single color copy mode, the intermediate transfer belt 19 remains in contact with the surface of the photosensitive member 9 with only the developing unit for that color being in a developing operation (spreading state) until the predetermined number of sheets is completed. The copying operation is performed while the belt cleaner 22 is in contact with the intermediate transfer belt 19 while being driven at a constant speed in the forward movement direction.

The intermediate transfer belt 19 has a volume resistance of 10 ⁷ to 10 ¹⁰ Ωcm, as in the case of the paper transfer roller 23-1, by dispersing a conductive material in a resin such as polycarbonate or polyester.

On the other hand, at a position facing the back surface of the paper transfer roller 23-1, a volume resistance of 10 ⁷ to 10 ¹² Ωcm is set by using a material that does not include a conductive material such as hydrin rubber for the core metal such as an installed metal. There is provided a belt drive roller 21 that is covered with a member.

  Further, this image forming apparatus is connected to a controller 37 for outputting well-processed image data to the computer 36 and the facsimile 38, and output other than the image data read by the scanner 1 is also possible. ing.

(2) Embodiment (A) Reversal of Black Image Formation Order in Copy Mode (Claims 1 to 7) The image forming apparatus according to this example has at least the following modes as copy modes. The user can select any mode as desired.

a "Automatic color selection" mode 1
At the same time as scanning for image formation, the document color is determined, and black image formation is first performed regardless of whether the color of the document image is black or color. When the color of the original image is black only, the copying process ends with black image formation. Even if the color of the original image is a color image, the first image is a black image portion. Based on the above determination, the copying process is not terminated even after the black image has been formed, and a command to enter the color image is entered. Is executed and the copying process is completed.

  When this mode is selected, reverse transfer does not occur in the case of a color image, but the copy time is shortened by no blur scan.

b "Automatic color selection" mode 2
In this mode, the image forming apparatus determines and executes all the order of image forming colors. For this reason, prior to scanning for image formation, a dedicated pre-scan for determining the document color is performed, and then a main scan for reading an image is performed.

  If the color of the original image is determined to be color in the pre-scan, the black image is placed at the last or any order after the first color image to prevent reverse transfer of the black image. In this way, the image forming order is changed. This mode corresponds to the copying mode or the first copying mode in which image formation with a black developer must be performed first.

  If it is determined that the color of the original image is black, there is no possibility of reverse transfer, so black image formation is performed from the beginning and the copying process is terminated. This mode in which black image formation is performed from the beginning corresponds to a copying mode or a second mode in which image formation with a black developer does not have to be performed first.

c “Full Color” Mode When the user knows in advance that the color of the original image is full color, the user executes this mode. In this mode, since the color of the document image is known in advance, the color of the document is mechanically changed as in “automatic color selection” mode 1 and “automatic color selection” mode 2 as in the automatic color selection mode. It is not necessary to make an automatic determination beforehand. If the user selects this mode, the black image order will be the last for other color images, or the next image after the first color image, and the next image after the first color image. Eliminate the problem of reverse transcription.

(B) Reversal of black image forming order by image data output medium (Claims 8 to 11) The image forming apparatus of this example is an output medium for inputting image data for image formation to the main body. As shown in FIG. 1, a computer 36 and a facsimile 38 connected to a scanner main body of the apparatus main body via a controller 37 are provided.

a When the image data output medium is a “scanner of the apparatus main body” The output medium on which the image data must first be imaged with a black developer in claims 9 to 11 is referred to in this example. Corresponds to the “scanner of the apparatus main body”.

  In this example, an image is formed without using the controller 37 shown in FIG. When the apparatus is used as a copying machine, image data is processed and imaged in real time by a scanner of the apparatus body. In this case, regardless of the mode, the image formation order of black images may be the first with respect to the image formation order of other colors, or the image formation order of black may be changed depending on the copy mode as described above.

b When the image data output medium is an image output medium such as the computer 36 or the facsimile 38 shown in FIG. 1, the output that does not require the first image formation with the black developer in claims 9 to 11 The medium corresponds to an output medium such as the computer 36 or the facsimile 38 referred to in this example. An image is formed via the controller 37 shown in FIG.

  In this case, the image forming apparatus has only a function as an image output apparatus that visualizes image data, and an image forming mode is defined in advance by the image output medium. The black image formation order is the last for the other colors.

  As described above, according to the present invention, various modes can be selected, and a mode without pre-scan and a mode for preventing reverse transfer can be arbitrarily selected according to the type of document and the output medium. is there.

1 is a front view illustrating a configuration of an image forming apparatus as an embodiment of the present invention. It is a front view of the principal part of the developing device as an embodiment of the present invention.

Explanation of symbols

14 BK developing unit 15 C developing unit 16 M developing unit 17 Y developing unit 17

Claims (11)

  An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, the image forming order by the black developer can be changed in accordance with the copy mode of the image forming apparatus.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, the image forming order with at least a black developer has a copy mode that is the first with respect to an image forming order with another color developer, and a copy mode that is the first or subsequent copy mode. Image forming apparatus.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, the image forming order with at least black developer has a first copying mode and a last copying mode with respect to the image forming order with other color developer. .   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier The forming apparatus has a copy mode in which image formation must first be performed with black developer and a copy mode in which image formation is not required first with black developer. An image forming apparatus, wherein the order of image formation by a developer is changed.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier The forming apparatus includes a first copying mode in which image formation with a black developer must be performed first, and a second copying mode in which image formation with a black developer need not be performed first. When the copy mode is selected, the image formation with the black developer is first performed, and when the second image formation mode is selected, the black image formation order is set to the first and subsequent images. Image forming apparatus.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier The forming apparatus includes a first copying mode in which image formation with a black developer must be performed first, and a second copying mode in which image formation with a black developer need not be performed first. When the copy mode is selected, image formation with black developer is the first, and when the second image formation mode is selected, the black image formation order is last. .   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier The forming apparatus has a copy mode in which image formation with black developer must be first, and a copy mode in which image formation with black developer need not be first, and which mode is the standard. An image forming apparatus characterized in that the order of image formation with a black developer is changed according to the selected copy mode.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, the image forming order by the black developer is changed in accordance with the output medium of the image data.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, if the image data is from an output medium that must first be imaged with a black developer, the black image sequence is first compared to the image sequence with the other color developer. An image forming apparatus characterized in that the image forming order with the black developer is set to the next or later when the output with the black developer is not necessarily the first.   An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, if the image data is from an output medium that must first be imaged with a black developer, the black image sequence is first compared to the image sequence with another color developer. An image forming apparatus characterized in that the image forming order with the black developer is last when the image forming with the black developer is based on an output medium that does not have to be the first. An image having a developing device that can be visualized with a developer of multiple colors including black, and finally transferring a visible image of each color visualized with the developer of the developing device onto a transfer material on an image carrier In the forming apparatus, the image forming order by the black developer is changed in accordance with the copy mode and the output medium of the image data.

Images