JPH08258332A - Color image forming device - Google Patents

Abstract

PURPOSE: To increase image forming velocity and to reduce power consumption and to reduce consumption of toner and to prevent scattering of toner in the case of forming the image of a special color copy in which formation of an image with original full color is unnecessary. CONSTITUTION: A color image forming device is equipped with both a toner color specification means 57 for specifying toner color used in the case of forming a color image and a control means 50 by which image forming actuation is performed by only toner color specified through the toner color specification means 57.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color copying machine or a color facsimile.

[0002]

2. Description of the Related Art Conventionally, as color image forming apparatuses, color copying machines of various types are known. For example, in a certain type of color copying machine, only one image reproducing unit for performing an image forming operation is used. When copying a full-color image provided, repeat the image forming operation multiple times to
I'm getting a color copy. That is, in this color copying machine, in the full color mode for obtaining one color copy, cyan (hereinafter referred to as C), magenta (hereinafter referred to as M), yellow (hereinafter referred to as Y) and black (hereinafter referred to as B).
The image forming operation for the four basic colors (referred to as K) (or the three colors Y, M, and C) is sequentially performed to form images of those colors, and these images are formed on one recording sheet. Overprinted. Further, when executing the single color mode, one image is formed by one image forming operation.
Therefore, in this color copying machine, the copying operation is significantly different between the single color mode and the full color mode.

Further, in such a color copying machine,
In order to shorten the image forming operation of four times (or three times), a part of the original image is read and its color is registered, and the original image of the registered color is regarded as a single color, and the image forming operation is performed once. The one that can be done only once is disclosed in Japanese Patent Laid-Open No. 4-29.
It is described in Japanese Patent No. 0381.

[0004]

Actual manuscripts are not limited to those requiring full-color copying, but texts that are marked with color markers, texts that are underlined in red or blue, etc. There are various things. When such a document is copied by the color copying machine, the color copying machine executes the image forming operation four times (or three times). However, in general, the original document as illustrated above is provided with a color identification display for calling attention, and it is not necessary to make the original full-color copy.

When copying such an original, the color copying machine described in Japanese Patent Application Laid-Open No. 4-290381 requires only one image forming operation, but the underline or the like of the original is read and recognized. Due to the work, the copying speed decreases and the power consumption increases, the toner consumption increases, the toner scatters, and the color identification display for calling attention is regarded as a single color. .
The present invention solves the above problems and improves the image forming speed, lowers power consumption, lowers toner consumption, and toners when forming an image of a special color original that does not require the original full-color image formation. An object of the present invention is to provide a color image forming apparatus capable of preventing scattering.

[0006]

In order to achieve the above object, the invention according to claim 1 forms a color image by using toners of three or more colors, and each of the toner colors is formed when the color image is formed. In a color image forming apparatus that performs an image forming operation with respect to the above, a toner color specifying unit that specifies a toner color used when forming a color image, and an image forming operation only for the toner color specified by the toner color specifying unit are performed. It is provided with a control means to perform.

According to a second aspect of the present invention, a color image is formed from a plurality of basic color image data by using toners of three or more colors, and an image forming operation is performed for each toner color when the color image is formed. In the color image forming apparatus for performing the above, when forming a color image, a priority unit that preferentially uses image data of a toner color having a higher toner color density and lower saturation than a plurality of basic color image data, and a toner to be used. Toner color number setting means for setting the number of colors, and toner to be preferentially used by the priority means with the number of colors set by the toner color number setting means from a plurality of basic color image data when forming a color image And a control means for performing only an image forming operation based on color image data.

[0008]

According to the present invention, the toner color used when forming a color image is designated by the toner color designating means, and the control means carries out the image forming operation only for the toner color designated by the toner color designating means. Let In the invention according to claim 2, the priority means preferentially uses the image data of the toner color having a higher toner color density and lower saturation than the plurality of basic color image data when forming the color image, and the toner to be used. The number of colors is set by the toner color number setting means. When the color image is formed, the control unit performs only the image forming operation based on the image data of the toner color which is preferentially used by the priority unit with the number of colors set by the toner color number setting unit from the plurality of basic color image data. To perform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an outline of an embodiment of the invention described in claim 1, and FIG. 3 is an enlarged view of a portion around a photosensitive drum and an intermediate transfer belt in this embodiment. This embodiment is an example of a color image forming apparatus including a digital color copying apparatus. A color image reading apparatus (hereinafter referred to as a color scanner) 1 illuminates a document 3 on a document table 2 with an illumination lamp 4, and a reflected light image thereof is transmitted to a color sensor 9 via mirror groups 5 to 7 and a lens 8. Image formation is performed and color image information of the original is color-separated and read for each of blue, green, and red, and converted into an electrical image signal. Color sensor 9
The blue, green, and red color-separated image signals obtained in step 1 are subjected to color conversion processing by an image processing unit (not shown) as image processing means based on their intensity levels, and BK, C, M, Y Is converted into image data of each toner color.

A color image recording device (hereinafter referred to as a color printer) 10 forms a full-color image by forming visible images of BK, C, M, and Y from image data of each color from the image processing unit and superposing them. Form.
Here, in order to obtain image data of toner colors of BK, C, M, and Y, the color scanner 1 receives a scanner start signal in timing with the operation of the color printer 10 from the control means, and the illumination lamp in FIG. 4 and optical system 5
By moving 7 to 7 in the direction of the left arrow, the document on the document table 2 is scanned, and the color scanner 1 repeats such an operation four times in total, and the color printer 2 causes the color printer 2 to output BK, C, M, Y from the image processing unit. Image data of each toner color of BK,
C, M, and Y visible images are sequentially formed, and these are superimposed to form a full-color image.

Next, the color printer 10 will be described. The writing optical unit 11 as an exposing unit converts the color image data from the image processing unit into an optical signal and performs optical writing corresponding to the original image on the photosensitive drum 12 as an image carrier to form an electrostatic latent image. To form.
The writing optical unit 11 includes, for example, a semiconductor laser 13
Is controlled by a light emission drive control unit (not shown) by the color image data from the image processing unit to emit laser light whose intensity is modulated by the color image data, and this laser light is rotationally driven by the motor 15. Rotating polygon mirror 14
Deflection scanning is performed by the f / θ lens 16 and the reflection mirror 1.
The light is applied to the photosensitive drum 12 via 7.

The photoconductor drum 12 is rotationally driven by a drive unit and rotates counterclockwise as shown by an arrow, around which a photoconductor cleaning device (pre-cleaning charge eliminator 18) is provided.
19), static elimination lamp 20, charging device 21, potential sensor 22, BK developing device 23, C developing device 24, M developing device 2
5, a Y developing device 26, a developing density pattern detector 27, an intermediate transfer belt 28, and the like are arranged.

Each of the developing devices 23 to 26 includes a photosensitive drum 12.
A developing sleeve 2 which holds a developer and rotates so as to face the photoconductor drum 12 in order to develop the electrostatic latent image thereon.
3a, 24a, 25a, 26a, and developing paddles 23b, 24 that rotate to scoop up and agitate the developer inside
b, 25b, 26b and toner concentration detection sensors 23c, 24c, 25c, 2 for detecting the toner concentration of the developer
6c and the like.

In the standby state, all of the four developing devices 23 to 26 are in the non-developing state, but the order of the developing operations of the developing devices 23 to 26 (BK, C, M and Y image forming operations) is performed. The order is the order of developing the electrostatic latent image in the order of BK, C, M, and Y. However, the order of image formation of each color is not limited to this, and may be any order.

At the start of the copying operation, the photosensitive drum 12
Rotates and is uniformly charged by the charger 21. Then, the color scanner 1 starts reading for obtaining BK image data at a predetermined timing, and the writing optical unit 11 receives the BK image data from the color scanner 1 via the image processing unit, based on the BK image data. A latent image is formed by performing optical writing with a laser beam. Hereinafter, the electrostatic latent image based on this BK image data is referred to as a BK latent image. The electrostatic latent images based on the C, M, and Y image data are also called C latent image, M latent image, and Y latent image.

In order to develop this BK latent image from its tip, the developing sleeve 23a starts rotating before the tip of the latent image reaches the developing position of the BK developing device 23, and the BK latent image is transferred to the BK toner. To develop. After that, the developing operation of the BK latent image area on the photosensitive drum 12 is continued, but the latent image rear end portion is BK.
At the time when the BK developing device 23 has passed the developing position, the BK developing device 23 is in the developing inoperative state. This is completed at least before the leading edge of the C latent image by the next C image data arrives. At this time,
The other developing units 24-26 remain in the non-developing state.

The BK toner image on the photosensitive drum 12 is transferred onto the surface of the intermediate transfer belt 28 which is driven at the same speed as the photosensitive drum 12 (hereinafter, the photosensitive drum 1).
The toner image transfer from 2 to the intermediate transfer belt 28 is referred to as belt transfer). The belt transfer is performed by applying a predetermined bias voltage to the transfer bias roller 29 that is in contact with the intermediate transfer belt 28 while the photosensitive drum 12 and the intermediate transfer belt 28 are in contact with each other. Photoconductor drum 1
2 is a static eliminator 18 before cleaning after transferring the BK toner image
The photoconductor cleaning device 19 including the components is subjected to static elimination and cleaning, and is again uniformly charged by the charger 21. It should be noted that the intermediate transfer belt 28 is a belt transfer in which four colors are overlapped by sequentially transferring the BK, C, M, and Y toner images sequentially formed on the photosensitive drum 12 to the same surface. An image is formed, and then, the belt transfer image is collectively transferred to a transfer paper. Intermediate transfer belt 28
The configuration and operation of the intermediate transfer belt unit including will be described later.

On the side of the photosensitive drum 12, the BK image forming process is followed by the C image forming process. In this C image forming process, the color scanner 1 starts reading for obtaining C image data at a predetermined timing. , Writing optical unit 11
On the basis of the C image data obtained from the color scanner 1 via the image processing unit, optical writing is performed on the photosensitive drum 12 with laser light to form a C latent image.

In the C developing device 24, the developing sleeve 24a starts to rotate with respect to the developing position after the trailing end of the preceding BK latent image has passed and before the leading end of the C latent image reaches the developing position. The image is developed with C toner. After that, the C developing device 24 continues the development of the C latent image area on the photoconductor drum 12, but at the time when the trailing end of the C latent image passes, the development is not performed as in the case of the BK developing device 23. It becomes a state. This is also completed before the leading edge of the next M latent image arrives. C on the photoconductor drum 12
The toner image is transferred onto the surface of the intermediate transfer belt 28 that is driven at the same speed as the photosensitive drum 12. The photoconductor drum 12 has a static eliminator 18 before cleaning after the transfer of the C toner image.
The photoconductor cleaning device 19 including the components is subjected to static elimination and cleaning, and is again uniformly charged by the charger 21.

On the side of the photosensitive drum 12, the C image forming process is followed by the M image forming process. In this M image forming process, the color scanner 1 starts reading to obtain M image data at a predetermined timing and then writes. The optical unit 11 performs optical writing with laser light on the photosensitive drum 12 based on M image data obtained from the color scanner 1 via the image processing unit to form an M latent image.

The M developing device 25 is
The developing sleeve 25a starts to rotate after the rear end of the previous C latent image has passed and before the front end of the M latent image arrives, and the M latent image is developed with M toner. After that, the M developing device 25 continues the development of the M latent image area on the photoconductor drum 12, but at the time when the rear end of the M latent image passes, the development is inoperative like the case of the C developing device 24. It becomes a state. This is also completed before the leading edge of the next Y latent image arrives. The M toner image on the photoconductor drum 12 is transferred onto the surface of the intermediate transfer belt 28 that is driven at the same speed as the photoconductor drum 12. Photoconductor drum 1
After the transfer of the M toner image, 2 is subjected to charge removal and cleaning by the photoconductor cleaning device 19 including the pre-cleaning charge remover 18, and is uniformly charged again by the charger 21.

On the side of the photosensitive drum 12, the M image forming process is followed by the Y image forming process. In this Y image forming process, the color scanner 1 starts reading to obtain Y image data at a predetermined timing and then writes. The optical unit 11 performs optical writing with laser light on the photoconductor drum 12 based on Y image data obtained from the color scanner 1 through the image processing unit to form a Y latent image.

In the Y developing device 26, the developing sleeve 26a starts rotating with respect to the developing position after the trailing end of the previous M latent image has passed and before the leading end of the Y latent image arrives, and the Y developing device 26 is rotated. The image is developed with Y toner. After that, the Y developing device 26 continues the development of the Y latent image area on the photosensitive drum 12, but the development inoperative state occurs when the rear end of the Y latent image passes. This is also completed after the trailing edge of the Y latent image has arrived. The Y toner image on the photoconductor drum 12 is transferred onto the surface of the intermediate transfer belt 28 that is driven at the same speed as the photoconductor drum 12.

Next, the intermediate transfer belt unit will be described. The intermediate transfer belt 28 includes a driving roller 31, a belt transfer bias roller 29, and driven roller groups 32 and 3.
The drive roller 31 is driven by a drive motor (not shown) to rotate the intermediate transfer belt 28. The belt cleaning device 35 includes a brush roller 35.
a, a rubber blade 35b, a contact / separation mechanism 35c for the intermediate transfer belt 28, and the like. After transferring the BK image of the first color by the belt, the C image, the M image, and the Y image are transferred to the belt transfer bias roller 29. When the brush roller 35a and the rubber blade 35b are in contact with each other,
It is separated from the belt transfer bias roller 29 by 5c.

The paper transfer unit 36 is composed of a paper transfer bias roller 36a, a roller cleaning blade 36b, a contact / separation mechanism 36c for the intermediate transfer belt 28, and the like. Although the paper transfer bias roller 36 a is normally separated from the intermediate transfer belt 28,
When the four-color superposed images formed in 8 are collectively transferred to the transfer paper, they are pressed by the contact / separation mechanism 36c at a timing to abut on the intermediate transfer belt 28, and the paper transfer bias roller 36a is predetermined. Bias voltage is applied from the bias power source to transfer the four-color superimposed image on the intermediate transfer belt 28 to the transfer paper passing between the paper transfer bias roller 36a and the intermediate transfer belt 28.

In this case, the transfer paper is the transfer paper cassette 37-
The selected one of 40 is fed to the registration roller 45 by one of the paper feed rollers 41 to 44, or is fed from the manual paper feed tray 46 to the registration roller 45 by the paper feed roller 41. The transfer paper is sent at the timing when the leading end of the four-color superimposed image on the intermediate transfer belt 28 reaches the paper transfer position.

The transfer paper on which the four-color superposed toner images are collectively transferred from the intermediate transfer belt 28 is conveyed to the fixing device 48 by the paper conveying unit 47 and is controlled to a predetermined temperature of the fixing device 48. The toner image is fused and fixed by the fixing roller 48a and the pressure roller 48b and is carried out to the copy tray 49 as a full-color copy. Further, the photoconductor belt 12 after the belt transfer is uniformly discharged by the pre-cleaning static eliminator 18 by the photoconductor cleaning device 19, and the surface is cleaned by the brush roller 19a and the rubber blade 19b. The surface of the intermediate transfer belt 28 after the toner image is transferred onto the transfer paper is cleaned by the cleaning unit 36, and at this time, the cleaning unit 36 is pressed against the intermediate transfer belt 28 by the contact / separation mechanism 36c.

At the time of repeat copying in which copying is continuously performed, the operation of the color scanner 1 and the image formation on the photosensitive drum 12 are started following the Y (fourth color) image forming process for the first sheet, and at a predetermined timing. Proceed to the second BK (first color) image forming process. Further, the intermediate transfer belt 28 has its surface cleaned by the cleaning device 35 following the step of collectively transferring the four-color superimposed image onto the first transfer sheet, and the second BK toner image is transferred onto the belt by the cleaning device 35. It
After that, the same operation as that for the first sheet is performed, and thereafter, the same operation is performed for each sheet.

The transfer paper cassettes 37-40 contain transfer papers of various sizes, and the paper feed rollers 41-44.
As a result, the transfer paper is fed to the registration roller 45 at a timing from the transfer paper cassette that stores the transfer paper of the size specified by the operation panel (not shown). The manual feed tray 46 is used for feeding OHP paper or thick paper in the manual feed mode.

FIG. 1 shows the electrical component of this embodiment. The control of the entire copying machine of this embodiment is performed by the system controller 50 which is composed of a microcomputer as a control means. The synchronization control circuit 51 generates a clock pulse that serves as a reference for control timing, and inputs and outputs various synchronization signals for synchronizing signals between the respective units. In this embodiment, the main-scanning synchronization signal, which is the basis of the scanning timing, is synchronized with the scanning start timing of the laser light due to the rotation of the rotary polygon mirror 14 in the color printer 10.

The color scanner 1 A / D-converts the red, green, and blue image signals obtained by scanning the original 3 to obtain 8 signals each.
Output as bit digital color image information. This image information is output to the color printer 10 after undergoing various processes in the image processing unit. Image processing unit is γ
Correction circuit 52, complementary color generation circuit 53, background removal (UCR)
It has a black generation circuit 54, a selector 55, and a gradation processing circuit 56.

The color image information from the color scanner 1 is γ corrected by the γ correction circuit 52, and the image information of each color of red, green and blue from the γ correction circuit 52 is complemented by the complementary color generation circuit 53. It is converted into image information of each Y, M, and C toner color. The UCR black generation circuit 54 combines the image information of all the Y, M, and C toner colors from the complementary color generation circuit 53, extracts the black component included in the combined image signal, and extracts this as the BK image information. And the black component is removed from the image information of each color of Y, M, and C from the complementary color generation circuit 53 and output.

The selector 55 is the system controller 50.
BK from the UCR black generation circuit 54 in response to an instruction from
Any one of the Y, M, and C toner color image information is selected and output to the gradation processing circuit 56. Gradation processing circuit 56
Binarizes the 8-bit image information from the selector 55 and performs dither processing on the binarized image information to enable the output of a halftone image. The binarized image information from the gradation processing circuit 56 is output to the color printer 10. Further, the operation board 57 can specify a toner color used when forming a color image, and an input signal from the operation board 57 is input to the system controller 50.

Next, a case of copying a red-blue original having only red information and blue information will be described. FIG. 4 shows a processing flow of the specific toner color copying of the system controller 50. In step S1, when the operator looks at the color of the red-blue original 3 and specifies the toner colors of the M toner and the C toner on the operation board 57 so as to perform copying with the M toner and the C toner, for example, the toner color is selected. A designation signal is input from the operation board 57 to the system controller 50.

The system controller 50 sends a signal BKFL using BK toner and a signal YF using Y toner.
A signal MFL that uses L and M toners, and a signal CFL that uses C toners are set according to the toner color designation signal from the operation board 57. Since it is a signal for specifying the toner color, MFL = 1 and CFL = 1. here,
Since BKFL, YFL, MFL, and CFL are cleared by the system controller 50 by default, BKFL
= 0 and YFL = 0.

Next, the system controller 50 checks the print start (copy start) signal from the copy button of the operation board 57 in step S2 to check whether or not the copy button is pressed, and the copy button is pressed. If so, in step S3, it is ticked whether or not BKFL = 1. The system controller 50 sets BKFL =
Since it is 0, it jumps to step S6 and ticks whether or not CFL = 1. Since CFL = 1, in step S7 the color scanner 1 starts reading the original image for obtaining the C image data, and The color printer 10 is instructed to start the image forming operation of the C toner color by the C image data from the gradation processing circuit 56 of the image processing unit.

Original images are sequentially read by scanning the original 3 by the color scanner 1, and the system controller 50 controls the selector 55 to send the C image data in the read image signal to the color printer 10. In the color printer 10, the writing optical unit 1
1 performs optical writing with laser light on the photoconductor drum 12 according to C image data from the gradation processing circuit 56 to form a C latent image, and the C latent image is developed by the C developing device 24 and the intermediate transfer belt 28. Is transcribed to.

The system controller 50 executes step S
In step 8, it is checked whether or not the reading of the original by the color scanner 1 and the creation of the C visible image by the color printer 10 (transfer of the C visible image to the intermediate transfer belt 28) are completed, and the reading of the original by the color scanner 1 is performed. Color printer 1
When the creation of the C image by 0 is completed, M is created in step S9.
Tick whether FL = 1.

The system controller 50 has MFL = 1.
Therefore, in step S10, the color scanner 1 is caused to start reading an original image for obtaining M image data, and the color printer 10 causes an image of an M toner color based on the M image data from the gradation processing circuit 56 of the image processing unit. Instruct to start the forming operation.

Original images are sequentially read by scanning the original 3 by the color scanner 1, and the system controller 50 controls the selector 55 to send the M image data in the read image signal to the color printer 10. In the color printer 10, the writing optical unit 1
1 performs optical writing with laser light on the photoconductor drum 12 according to the M image data from the gradation processing circuit 56 to form an M latent image, and the M latent image is developed by the M developing device 25 and the intermediate transfer belt 28. It is transferred on top of the C image.

The system controller 50 executes step S
At 11, the document is read by the color scanner 1 and the M image is made by the color printer 10 (intermediate transfer belt 28
(Transfer of M visible image to M) is finished, and when the reading of the original by the color scanner 1 and the creation of the M visible image by the color printer 10 are finished, step S12
Then, tick whether YFL = 1.

The system controller 50 sets YFL = 0.
Therefore, the process returns and the superposed image of the C visible image and the M latent image formed on the intermediate transfer belt 28 is collectively transferred to the transfer paper by the paper transfer unit 36 as in the normal copying operation. The transfer sheet is conveyed to the fixing device 48 by the paper conveying unit 47, the toner image is melted and fixed by the fixing device 48, and the transfer sheet is conveyed to the copy tray 49 as a two-color copy.

The system controller 50 is BK
If FL = 1, steps S3 to S4
Then, the color scanner 1 starts reading the original image for obtaining the BK image data, and the color printer 10 starts the image forming operation of the BK toner color by the BK image data from the gradation processing circuit 56 of the image processing unit. Instruct to start.

Original images are sequentially read by scanning the original 3 by the color scanner 1, and the system controller 50 controls the selector 55 to send the BK image data in the read image signal to the color printer 10. In the color printer 10, the writing optical unit 1
1 is BK by performing optical writing with a laser beam on the photosensitive drum 12 according to BK image data from the gradation processing circuit 56.
A latent image is formed, and this BK latent image is developed by the BK developing device 23 and transferred onto the intermediate transfer belt 28.

The system controller 50 executes step S
5, the document is read by the color scanner 1 and the BK image is created by the color printer 10 (intermediate transfer belt 28
Check whether or not the transfer of the BK image to the
When the reading of the document by the color scanner 1 and the creation of the BK visible image by the color printer 10 are completed, step S
Proceed to 6.

Similarly, the system controller 50 displays the Y
If FL = 1, steps S12 to S
In step 13, the color scanner 1 starts reading an original image for obtaining Y image data, and the color printer 10 causes the Y image data from the gradation processing circuit 56 of the image processing unit to form an image forming operation of Y toner color. Instruct to start.

Original images are sequentially read by scanning the original 3 by the color scanner 1, and the system controller 50 controls the selector 55 to send the Y image data in the read image signal to the color printer 10. In the color printer 10, the writing optical unit 1
1 performs optical writing with laser light on the photoconductor drum 12 according to Y image data from the gradation processing circuit 56 to form a Y latent image, and the Y latent image is developed by the Y developing device 26 and the intermediate transfer belt 28. Transcribed on. In step S14, the system controller 50 checks whether or not the reading of the document by the color scanner 1 and the creation of the Y visible image by the color printer 10 (transfer of the Y visible image to the intermediate transfer belt 28) are completed, and the color scanner is checked. When the reading of the original by 1 and the creation of the Y visible image by the color printer 10 are completed, the process returns.

As described above, the present embodiment is an embodiment of the invention described in claim 1, in which a color image is formed by using toners of three or more colors, and each color of toner is used when forming a color image. In a color image forming apparatus that performs an image forming operation for each of them, an operation board 5 having a toner color designating unit that designates a toner color used when forming a color image.
7 and the system controller 50 which also serves as a control means for performing an image forming operation only for the toner color designated by the toner color designating means, so that a special color original document which does not require the original full-color image formation is provided. By designating the minimum toner color with the toner color designating means when forming an image, unnecessary toner consumption and toner scattering during image formation can be suppressed, and low power consumption can be achieved. Only the image forming operation for the toner color can be performed, and the image forming speed can be improved.

FIG. 5 shows an electric component part of an embodiment of the invention described in claim 2. In this embodiment, the maximum value (MAX) detection circuit 58 is provided in the above embodiment, and the system controller 50 executes the processing flow of the specific toner color copying and the limited toner color number copying shown in FIGS. 6 and 7. That is,
As shown in FIG. 7, the operation board 57 has a toner color number setting means for setting the toner color number to be used, and step S21
When the operator specifies the toner color number n to be used by the operation board 57, the signal of the toner color number n is input to the system controller 50.

Next, the system controller 50 checks the print start (copy start) signal from the copy button of the operation board 57 in step S22 to check whether the copy button is pressed, and the copy button is pressed. In step S23, the color scanner 1 is caused to perform a prescan to read the original 3. Image signals of red, green, and blue from the color scanner 1 are passed through a γ correction circuit 52, a complementary color generation circuit 53, and a UCR black generation circuit 54, and toner colors Y, M, C, and BK required for reproducing an original image.
Image data y, m, c, bk are obtained.

Then, in step S24, the MAX detection circuit 58 detects the maximum value (high density) of the image data y, m, c, bk of each toner color from the UCR black generation circuit 54 during the prescan, The detection result is, for example, y = m = c>
It is assumed that it is bk. The system controller 50 checks in step S25 whether or not the prescan is completed. When the prescan is completed, in step S26, the detection result of the MAX detection circuit 58 and the image data of the basic colors BK, C, M, and Y are obtained. The toner color of the used toner color number n is determined according to the priority order of No. 1, and a signal for using the toner color is set.

That is, the system controller 50
If the number n of toner colors used is, for example, n = 2, image data of toner colors having a higher toner color density and lower saturation than the basic color image data of BK, C, M, and Y when forming a color image. Is preferentially used, that is, the priority is set to toner color (BK>C>M> Y), and n toner colors having high density Y and M are detected from the detection result of the MAX detection circuit 58. , C with high priority among M and C
And set MFL and CFL corresponding to the toner colors M and C among BKFL, YFL, MFL and CFL. Since BKFL, YFL, MFL, and CFL are cleared by the system controller 50 by default, BKFL = 0 and YFL = 0.

Thereafter, the system controller 50 proceeds to step S3 as shown in FIG. 6 and executes steps S6 to S11 by MFL = 1 and CFL = 1 as described above.
Is performed to sequentially form an M visible image and a C visible image and transfer them onto the intermediate transfer belt 28. The superposed image of the M latent image and the C visible image is transferred onto the transfer paper by the paper transfer unit 36. It is transcribed together. The transfer sheet is conveyed to the fixing device 48 by the paper conveying unit 47, the toner image is melted and fixed by the fixing device 48, and the transfer sheet is conveyed to the copy tray 49 as a two-color copy.

As described above, the present embodiment is an embodiment of the invention described in claim 2, in which a color image is formed by using a plurality of basic color image data using toners of three or more colors, and a color image is formed. In a color image forming apparatus that performs an image forming operation for each of the toner colors when the color image is formed, an image of a toner color that has a higher toner color density and a lower saturation than a plurality of basic color image data when forming a color image A system controller 50 having a priority means for preferentially using data, an operation board 57 having a toner color number setting means for setting the number of toner colors used, and a plurality of basic color image data when forming a color image. There is a control means for performing only an image forming operation with the image data of the toner color which is preferentially used by the priority means with the number of colors set by the toner color number setting means. Since the system controller 50 is provided, the toner color number is set when forming an image of a special color original that does not require the original full-color image formation, so that unnecessary toner consumption and toner scattering during image formation are possible. It is possible to reduce the power consumption, reduce the power consumption, perform only the image forming operation for the minimum toner color, and improve the image forming speed. Further, the operator does not need to consider the toner color to be used, and only needs to input the number n of toner colors to be used.

In the above embodiment, the MAX detection circuit 5
8 detected the maximum value (high density) of the basic color image data from the UCR black generation circuit 54 during the prescan,
You may make it detect the maximum value (high density) of basic color image data, such as red, green, and blue. Further, the present invention can be similarly applied to color facsimiles other than digital color copying machines.

[0056]

As described above, according to the first aspect of the invention, a color image is formed by using three or more color toners, and when the color image is formed, an image is formed for each toner color. In a color image forming apparatus that operates, a toner color designating unit that designates a toner color used when forming a color image, and a control unit that performs an image forming operation only on the toner color designated by the toner color designating unit. Since it is equipped with, the minimum toner color is specified by the toner color specification means when forming an image of a special color original that does not require the original full-color image formation, thereby eliminating unnecessary toner consumption during image formation. Toner scattering can be suppressed, power consumption can be reduced, and only the image forming operation for the minimum toner color can be performed, thereby improving the image forming speed. Rukoto can.

According to the second aspect of the invention, a color image is formed from a plurality of basic color image data using toners of three or more colors, and when forming a color image, an image is formed for each toner color. In a color image forming apparatus that performs a forming operation, a priority unit that preferentially uses image data of a toner color having a higher toner color density and lower saturation than a plurality of basic color image data when forming a color image, and Toner color number setting means for setting the number of toner colors to be used, and when the color image is formed, the priority number means preferentially uses a plurality of basic color image data with the number of colors set by the toner color number setting means. And a control means for performing only an image forming operation based on the image data of the toner color
By setting the number of toner colors when forming an image of a special color original that does not require the original full-color image formation, unnecessary toner consumption and toner scattering during image formation can be suppressed and low power consumption is achieved. Therefore, the image forming operation can be performed, and the image forming speed can be improved.
Further, the operator does not need to consider the toner color to be used, and only needs to input the number of toner colors to be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electric component section of an embodiment of the invention described in claim 1. FIG.

FIG. 2 is a sectional view showing the outline of the embodiment.

FIG. 3 is a cross-sectional view showing an enlarged part of the embodiment.

FIG. 4 is a flowchart showing a processing flow of specific toner color copying of the system controller in the embodiment.

FIG. 5 is a block diagram showing an electric component section of an embodiment of the invention described in claim 2;

FIG. 6 is a flowchart showing a processing flow when copying a specific toner color of the system controller in the embodiment.

FIG. 7 is a flowchart showing a processing flow when copying the limited toner color number of the system controller in the embodiment.

[Explanation of symbols]

 1 Color Scanner 10 Color Printer 50 System Controller 55 Selector 57 Operation Board 58 MAX Detection Circuit

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Claims (2)

[Claims] 1. A color image is formed in a color image forming apparatus which forms a color image using toners of three or more colors and performs an image forming operation for each toner color when the color image is formed. A color image forming apparatus comprising: a toner color designating means for designating a toner color to be used at that time; and a control means for performing an image forming operation only on the toner color designated by the toner color designating means. 2. A color image forming apparatus for forming a color image from a plurality of basic color image data using toners of three or more colors and performing an image forming operation for each toner color when forming the color image. A priority means for preferentially using image data of a toner color having a higher toner color density and lower saturation than a plurality of basic color image data when forming a color image, and a toner for setting the number of toner colors to be used. An image based on the color number setting means and the toner color image data that is preferentially used by the priority means with the number of colors set by the toner color number setting means from a plurality of basic color image data when forming a color image. A color image forming apparatus comprising: a control unit for performing only a forming operation.