JPH02211460A - Multicolor image forming device - Google Patents

Abstract

PURPOSE:To eliminate the erroneous judgment of colors even when there is isolated single color data between the 1st continuous color data and 2nd continuous color data on color CCDs, by converting this color data to any of the above- mentioned continuous data. CONSTITUTION:While the color data inputted by each piece from a color judging section 54 are latched by latches 81, 82 operated by a clock (not shown) synchronized with these inputs, the (n-2)th, (n-1)th, and n-th color data are inputted to a ROM 83 for removing the erroneous judgement. The ROM 83 indexes the table therein, removes the erroneous judged color data by converting the (n-1)th color data to the color data of either of the (n-2)th or n-th color data when all pieces of the color data are different. The converted color data is outputted to a data converting section 55 of the ensuing stage, which section converts the color data of the read unit to the color data of an erase unit. Since the areas of the read unit of the color CCDs 51 and the erase unit of an editing eraser vary, the conversion of the color data of the read unit by the CCDs 51 to the color data of the erase unit by the editing eraser is executed in the converting section 55.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus that reproduces multicolor images using an electrophotographic process.

(Prior art) Conventionally, an original image is read as image data for each color by an original reading means such as a CCD array, and a laser is driven and controlled based on the read color data to create electrostatic latent images for each color on a photoreceptor. Multicolor image forming apparatuses that reproduce multicolor images by repeating the steps of forming an image, developing it using toner of a corresponding color, and transferring the toner image to an intermediate transfer medium are well known.

On the other hand, an electrostatic latent image is formed on a photoreceptor by scanning the original, and depending on the color to be reproduced, the electrostatic latent image other than the part to be converted into a toner image is used with an LED array or the like for each toner developer used. There is also known a multicolor image forming apparatus that reproduces a read document in color by repeating the operations of erasing the toner with an eraser, converting it into a toner image, and transferring it to an intermediate transfer medium for each toner ( (See Japanese Patent Application Laid-open No. 194469/1983).

(Problems to be Solved by the Invention) All of these methods use a COD in which a reading unit of a set of three photoelectric conversion elements each having a filter for RGB is arranged in a row as a document reading means.

Although CCDs have become much smaller due to recent technological advances, they still have drawbacks. It is fine if the l reading unit covers only one color, but if two colors cover the l reading unit, such as at a color change, color misjudgment (so-called color ghost) will occur. . For example, if the l reading unit falls on the boundary between white and black, the photoelectric conversion element cannot judge that area separately as white and black, but judges it as red or cyan, which are completely unrelated. Sometimes I end up doing it. In a multicolor image forming device,
When such a misjudgment occurs, colors that do not originally exist in the original are reproduced in the reproduced image, which not only leads to a decrease in reproducibility (but also because colors that do not exist in the original are reproduced in the reproduced image). The developing device for that color will be operated, resulting in an extremely unnecessary cost in terms of expense and time.

An object of the present invention is to solve the drawbacks peculiar to elements such as the above-mentioned color CCD, which separate and read colors and judge colors, that is, misjudgment of colors.

(Means for Solving the Problems) In order to solve the above-mentioned problems, a multicolor image forming apparatus according to the present invention irradiates light onto an original and uniformly applies the reflected light to the surface of a photoreceptor. is exposed to light to form an electrostatic latent image corresponding to the original image, while the original reading means separates and reads the original image for each color, and based on the obtained image data for each color, the erase means The photoconductor on which the electrostatic latent image has been formed is selectively irradiated with light to leave the area to be developed with toner and erase the rest, and then the remaining electrostatic latent image is developed using toner of the corresponding color. The step of transferring the developed toner image to an intermediate transfer medium is repeated at least once to form a multicolor toner image on the intermediate transfer medium, and then transferred to paper and left to stand for a while to form a multicolor toner image. In a multicolor image forming apparatus that forms an image, color data read by an original reading means is input, and a single color data is generated between continuous first color data and continuous second color data on the original reading means. If the third color data is detected, the third color data is converted into either the first color data or the second color data and outputted. It is characterized in that the obtained color data is used as image data.

(Function) In a multicolor image forming apparatus, when there is an isolated nest of color data between one continuous color data and another continuous color data on the color CCD used for document reading, this is It is assumed that the color data has been misjudged, and is converted into one of the above continuous color data.

(5! Examples) Examples of the present invention will be described below with reference to the attached drawings.

Structure of Copying Machine FIG. 1 is a schematic sectional view of a copying machine to which a multicolor image forming apparatus according to the present invention can be applied.

A photoreceptor drum 3, which is an electrostatic latent image carrier, is installed approximately in the center of the copying machine main body l so that it can be rotated in the direction of arrow a. Eraser 5, developing device 6, transfer device 11. A cleaning device 22 and a main eraser 23 are installed.

The editing eraser 5 is an LRD array in which LED elements are arranged in a holder arranged along the axial direction of the photosensitive drum 3, and this editing eraser 5 is schematically shown in FIG. Each LED 65 faces the photosensitive drum 3, and is arranged in a line in a direction perpendicular to the plane of the paper of FIG. Further, the pitch P of each LED 65 is set to 1.2 m in this embodiment. As will be described later, the timing of turning on and turning off each LED 65 is individually controlled.

The developing device 6 consists of four developing devices 7.8, 9.10,
As a whole, these directions are in the vertical direction (arrows).

b' direction) and remove the photoreceptor drum 3 from any developing device.
The toner can be supplied to the surface of the developing device 7.
Toners 1 to 10 contain toners containing yellow toner (TV), magenta toner (Tm), cyan toner (Tc), and black toner (Tbk), respectively. Note that the developing device 6 is not limited to a type that can move up and down as described above, but may be of a type that can selectively supply toner of different colors to the photoreceptor drum 3.

The transfer device 11 temporarily transfers the toner supplied onto the photosensitive drum 3 onto the transfer belt 15 and holds it.
This transfer belt 15 has a dielectric material such as polyethylene on the surface of a conductive base made of conductive polyester containing carbon resin, etc., and is wound around rollers 12, 13, and 14 arranged parallel to the photoreceptor drum 3. It is supported by

A pressure roller 16 is disposed inside the transfer belt 15 between the rollers 12 and 13, and these rollers approach and separate from the photoreceptor drum 3 integrally, and the vertical movement of the pressure roller 16 causes the transfer belt 15 to be is in contact with the photoreceptor drum 3 and separated from it. Further, a guide plate 18 is provided along the transfer belt 15 between the rollers 13 and 14, and a cleaning device 19 is provided on the outside facing the guide plate.
, a static eliminating charger 20, and a charging charger 21 are arranged. Further, a transfer belt 15 is provided below the roller 14.
A secondary transfer charger 24 facing the secondary transfer charger 24 and a separation charger 25 located on the side thereof are provided.

An optical system 27 is arranged at the top of the copying machine main body l.

In this optical system 27, an exposure lamp 29 and a first mirror 31 are installed on the first slider 28, and the first slider 28 is moved along the arrow d along the document table glass 26 provided at the top of the copying machine main body l. It is possible to scan in the direction.

A second slider 32 is arranged at the rear of the first slider 28, and a second mirror 33 and a third mirror 34 are provided therein, and the second slider 32 is moved in the direction of arrow d in synchronization with the first slider 28. In this case, the scanning is performed at half the speed of the first slider 28. Further, a main lens 35 and a fourth mirror 36 are fixed in front of the second slider 32 (on the scan side), and a fifth mirror 37 is arranged above the photosensitive drum 3. Furthermore, a filter 38 is provided between the main lens 35 and the fourth mirror. In the vicinity of the main lens 35, color 〇〇D51 and Hikara-C0D5 are provided.
14: [CCD lens 51 for focusing the draft image
a is fixedly arranged.

As the filter 38, two types of filters, an infrared cut filter and a cyan filter, are configured to be switchable in front of the main lens 35.

A copy paper feeding/conveying system is provided at the bottom of the copying machine main body l, and the paper feeding section 40 is composed of a first paper feeding section 41, a second paper feeding section 42, and a manual paper feeding section 43. has been done.

The copy paper 100 in the first paper feed section 41 is fed to the paper feed roller 4
4. The copy paper 100 manually fed from the manual paper feeder 43 is transferred to the transport roller pair 45.
Accordingly, the copy paper 100 in the second paper feed section 42 is further fed by the paper feed roller 47. Then, the fed copy paper 100 is moved to a timing roller 46, respectively.
The copy paper 100 is conveyed to the opposing part between the transfer belt 15 and the secondary transfer charger 24, and passes there.
The sheet is sent to a fixing device 49 by a conveyor belt 48 and then discharged to a paper discharge section 30 .

Operation of the Copying Machine The basic copying operation of the copying machine having the above configuration will be explained with reference to FIG.

When the print switch is turned on with an original placed on the original table glass 26, the photosensitive drum 3 rotates in the direction of arrow a based on the drive of the main motor 2, and
Its outer peripheral surface is charged to a predetermined potential by the discharge of the charger 4.

In the optical system 27, the sliders 28, 32 each correspond to the arrow d.
The reflected light of the light irradiated onto the document from the exposure lamp 29 is reflected by the mirrors 31, 33, 34 and the filter 3.
8. The photoreceptor drum 3 is exposed to light through the lens 35 and mirrors 36 and 37 to form an electrostatic latent image.

Next, the surface of the photoreceptor drum 3 is irradiated with light from the editing eraser 5 to the portions corresponding to the front end, rear end, and both ends of the image area on which the electrostatic latent image is formed, so that electric charges are generated. removed. As will be described later, based on the detection result of color 〇〇D5I, the charge of the image corresponding to the predetermined color is also erased.

Subsequently, toner is supplied to the electrostatic latent image from a predetermined developing device at a portion facing the developing device 6, and a toner image is obtained.

On the other hand, in the transfer device 11, the main motor 2 drives the pressure roller 16 to move upward to the state shown in FIG. is lightly touched, and in this state arrow C
While being rotated in the direction, a charge is uniformly applied by the electrification charger 21. Note that the moving speed of the transfer belt 15 is set to be the same as the circumferential speed of the photoreceptor drum 3, so that there is no relative variation between the two.

With the transfer device 11 set as described above,
When the toner image formed on the surface of the photosensitive drum 3 is sent to the contact portion with the transfer belt H5, the toner image is electrostatically applied to the transfer belt 15 based on the charge applied by the charger 21. Primary transfer is performed.

After the photosensitive drum 3 has passed through the portion facing the transfer belt 15, residual toner is removed by a cleaning device 22, and then the residual charge is erased by a main motor 23 in preparation for the next image formation.

The toner image transferred to the transfer belt 15 is
5 is conveyed in the direction of arrow C.

The above copying operation is repeated for each color of yellow, magenta, cyan, and black, and toner images formed in each color are transferred onto the transfer belt 15 in an overlapping manner to form a multicolor image.

On the other hand, the copy paper 100 fed from the paper feed section 40 is fed out from the timing roller 46 in synchronization with the toner image, and at the portion facing the secondary transfer charger 24, the copy paper 100 is fed by the discharge of the secondary transfer charger 24. The toner image is secondarily transferred onto copy paper 100.

The copy paper 100 on which the toner image has been transferred is separated from the transfer belt 15 by the separation charger 25 and conveyed to the fixing device 49 by the conveyor belt 48, where the toner image is melted and fixed, and then transferred to the paper discharge section 30. is discharged.

Note that, after passing through a portion facing the second transfer charger 24,
The belt 15 that has lost toner is removed by a cleaning device 19
The residual toner is removed at the part facing the charger 2.
At 0, residual charges are erased to prepare for the next transfer operation.

Operation Panel FIG. 3 is a plan view of an operation panel provided in the copying machine main body 1, which instructs the copying machine main body 1 to perform various operations.

A key 300 is a print switch for starting a copying operation, and a key group 302 is a numeric keypad for setting the number of copies and inputting other information. Also, 30
1 is an LED for displaying the number of copies set using the numeric keypad 302.

Keys 305 and 306 are keys for setting the copy magnification, and 307 is an LED that displays the copy magnification. Keys 308 and 310 are manual exposure setting keys, key 308 is used to increase the exposure, and key 310 is used to decrease the exposure. This exposure level is displayed by LED group 311. Further, the key 309 is a key for setting automatic exposure, and the LED 322 is for indicating that automatic exposure is set. Key 303 is a clear/stop key, and key 304 is an interrupt key. 323 is a display area showing the status of the copying machine. 323a is a display indicating that the capacity of waste toner is exceeded, and 323b is an interrupt key 304.
323c is a paper jam display, and 323d is a toner empty display. 325
330 are switches and selection display LEDs corresponding to the developing devices of each color, respectively. Also, 331 and 332 are l
These are a switch for switching between the development copy mode and the multiple development copy mode, and a selection display LED.

Control configuration of the copying machine FIG. 4 is a schematic block diagram of the control of the copying machine in this embodiment.

Usually, a copying machine is not controlled by one microcomputer but by a plurality of microcomputers. In this embodiment, it is controlled by three microcomputers.

The main control unit 150 is a part that controls the processes of the copying machine, that is, sequence control of paper feeding, conveyance, fixing, exposure, etc., and control of input and display of the operation panel and communication between microcomputers.

The scanner control unit 160 controls a scan motor (not shown) that drives the first slider 28 and the second slider 32 of the optical system 27.

The ECP 58 mainly controls the data processing section 70, which includes the color separation section 52, the shading correction section 53, the color judgment section 54, the misjudgment line unprocessed section 80. Data conversion section 55, memory section 56, color limitation detection section 57, ECP
58 and an editing eraser controller 59, which will be briefly explained below.

Color〇〇The color information of the original read by D51 is R,
Since it is output as a G and B-column analog signal, it is separated into R, G, and B parallel signals by the color separation section 52, and further converted into a digital signal and output.

The shading correction section 53 corrects variations in output that occur due to various causes.

The color determination unit 54 determines the color for each unit of document reading by the CCD 51.

The misjudgment removal processing section 80 is related to the present invention and is provided to restore the misjudgment color generated by the color judgment section 54 to the older brother's color. This eliminates color misjudgments that occur at the transitions between colors of the original due to the drawbacks of color COD.

Since the reading unit by the color CD 51 and the erase unit by the editing eraser 5 have different areas, the data conversion unit 55 converts the color data in the reading unit into color data in the erase unit.

The color data after conversion by the data conversion unit 55 is stored in the memory unit 5.
6 and input to the color limited detection fi57.

The color limitation detection unit 57 detects only the colors that are actually reproduced when reproducing the original image.

The ECP 58 reads the contents of the memory section 56 and controls the edit eraser controller 59 to control the edit eraser 5 based on the contents of the color data.

The above blocks are connected and synchronized by communication lines for exchanging data.

Original Reading FIG. 5 is a flowchart showing the original reading operation in the control configuration of the copying machine shown in FIG.

In reading the original, first, the R, G, and B data output from the color CD 51 is converted into color data for each CCD reading unit (step #l), and then the present invention, which will be described later, is performed. A process for removing misjudgment (see FIG. 8) is performed (step #2), and a process for converting the color data of the COD reading unit into color data of the erase unit by the editing eraser 5 is performed (step #2). 3) Store the data in memory (step #4). This process is performed, for example, for A3 size documents. Although the process is divided into steps #1 to #4, in reality these processes are repeated.

Color Misjudgment Removal Process Here, the color misjudgment removal process (FIG. 5, Step #2) caused by the color CD will be explained.

(2) Principle of color misjudgment generation Before explaining the color misjudgment removal process, first, the principle of color misjudgment generation will be explained.

FIG. 6 shows an example of output characteristics for each of R, G, and B detected by a color COD sensor for each of seven colors of standard brightness.

From this figure, it can be seen that yellow has a high output of R and G, red has a high output of R1, and cyan has a high output of G and B.

Based on the relative ratio and absolute value of these R, G, and B outputs, the color determination section 54 determines color data for each reading unit.

Next, FIG. 7 shows an example of a document, sensor arrangement, sensor output, and copying state, and explains the principle behind the occurrence of erroneous judgments. For convenience, only the width corresponding to one sensor line is shown for the original and copy states.

The sensor arrangement is Rt, c, Bt from the left in the figure.

R,,G,,B,,R,,G,,R3,R,,G,,B
,.

Rs, Gs, Bs, R1G@, Bs, Rt, Gt, By
The order is as follows. Here, the same subscript indicates that they are included in the same reading unit.

The 1st, 2nd, 4th, 5th, and 7th reading units completely cover the white, white, black, black, and white of the document, respectively, and the sensor output direction is also output correctly, so that The copy status is also normal. However, on the other hand, the 3rd and 6th reading units are located exactly at the boundary between white and black, R3 is white, Gs, R3 is black, and R1
is black, G.

Since B is overlaid on white, only the R output is high in the third reading unit, and the G and B outputs are high in the sixth reading unit. In the end, due to the COD sensor output characteristics shown in FIG. 6, red and cyan are erroneously determined, respectively, and copying cannot be performed correctly.

■Principle of misjudgment removal processing Therefore, if it is possible to detect in advance that a color misjudgment has occurred, the misjudgment part can be converted to one of the two colors that caused the misjudgment. Judgment can be removed.

Since color misjudgments occur at the boundaries between colors as described above, three adjacent color data converted by the COD sensor are examined for each line as one block. That is, the color data in a certain l block is D m-2+ D
Assume that they are arranged in the order *-1s D @. When all of these color data are different, the middle D s-1 is determined to be the misjudged color data.

In this way, it may be determined to be an erroneous judgment, or the result may be -1.

D, to eliminate misjudgments. At this time, various methods can be considered as to which color data to convert, but in this embodiment, the concept of color priority is introduced.

Here, an example of how to determine the priority order will be explained. Considering the actual color development of plotters, printers, felt-tip pens, markers, etc., the colors are usually black, red, cyan, green, and yellow, so the priority order is l... black 2... red 3... ...Cyan 4...Green 5...Yellow 6...Magenta 7...White can be used.

In this way, the priorities are determined in advance and, for example, D,
If -, is red and D, is magenta, red has a higher priority, so 5I) e-1 is removed, and -2's color data (red)
I decided to convert it to .

(2) Flow of Misjudgment Elimination Process The misjudgment removal process described above is shown in chart 70 of FIG. The explanation will be given below.

First, in order to determine whether it is a misjudgment, D a-1+D,
, , D are different color data (step #21).

In the case of all different color data (Y E S ), D−+
is determined to be misjudged data (step #22), and then %
Which color data to convert to, DS-1 or -8, is determined based on a predetermined color priority order (step #23), n, -.

and find out which has higher priority (step #
24) If ,D,, is high (YES), ,p,−.

Convert to -□ color data Step #25), D
If , is high (No), D, -1 is converted into color data of , (step #26).

This process converts the misjudged color data to the original color data with a higher priority, so that a reproduced image that looks natural can be obtained.

(2) Example of Misjudgment Elimination Processing FIGS. 9 and 1θ show examples of misjudgment elimination processing using this priority order.

In FIG. 9(a), it is checked whether or not a misjudgment has been made regarding the block whose range is indicated by an arrow. Here, the color data is red, red, and cyan, and since the three colors are not different from each other, it cannot be said that this block is a misjudgment. However, next time, by shifting the color data by one,
Considering the block indicated by the arrow in Figure (b), the color data is red, cyan, and black, and it is determined that an erroneous judgment has been made for this block, and the color data in the middle, cyan, is regarded as the erroneous judgment data. Since the priority order of colors is black>red, cyan is converted to black as shown in Figure Wc9 (C).

10 is similar to FIG. 9. Figure 10 (
Regarding the block a), the color data is red, red, and cyan, and it is not possible to determine whether it is a misjudgment or not, but as shown in Figure 1O (
Considering block b), the color data is red, cyan, and yellow, so cyan is considered to be misjudgment data, and the priority order of colors is red>yellow, so the color data is as shown in Figure 1O (C). , convert cyan to red.

Data Processing Unit FIGS. 11(a) and 11rXJ(b) are more detailed block diagrams of the data processing unit 7o shown in FIG. 4.

This will be explained below.

The image information detected by the color CD51 is R,
It is output as a G and H serial analog signal.

FIG. 12 shows an output example. From the figure, it can be seen that the outputs obtained when light passes through the R, G, and B filters are sequentially generated as serial analog values. The shaded area represents the signal level that is document information. (R-, G-1B6), (R
-++, G-+i, B-++) ,... are each 1
One set is the color information for each reading unit of the document.

In the color separation unit 52, only the R, G, and B signal components are extracted, and the timing is determined and decomposed into parallel signals. /D conversion is performed to convert it into a digital signal. This digital signal is sent to the shading correction section 53.

Shading correction! 53, the digital signals are selected for each of R, G, and B by the selector 204, read out via the buffer 205, and are stored in the shading correction RA and M2O7 according to the address signal by the address generation unit 206, and the contents and shading correction are performed. According to the contents of the shading correction ROM 208 in which a table for shading is stored, variations in the appearance peculiar to pixels of the color CCD 51 and variations in output caused by the optical system 27 are corrected.

Note that the shading correction RAM 207 stores data obtained by reading one line of a reference white pattern (not shown) provided on the back side of a document scale provided at the end of the document placement portion of the document placement table.

The shading-corrected data is sent to the color determining section 54. The sent data is latched 209 for each R, G, and 3.
latched by a to 209c, and refer to the table in the color determination ROM 210 to determine which of the seven colors yellow, magenta, cyan, black, red, green, and white it is based on the values of each component of R, G, and B. and converted to color data. In Figure 13,
An example of output data from the color determination unit 54 is shown. As shown, the color data is coded for each color and output as a 3-bit digital signal. ooo""001","
010'', ``011'', ``100'', ``101',
"l l O"Hasot"L soit, yellow, magenta,
Represents cyan, green, red, black, and white.

However, when the color judgment unit 54 judges the color, there is a possibility that an erroneous judgment may occur due to the above-mentioned characteristics of the color CD. Misjudgment removal processing unit 8 according to the present invention in step
Color data is input to 0.

The color data inputted one by one from the color determination section 54 is passed through a latch 8 that operates with a clock (not shown) synchronized with the input.
While latched by 1.82, the (n - 2)th, (
n-1)th and nth color data are ROM for removing misjudgment.
83. ROM83 for removing misjudgment
indexes the table inside, and if these color data are all different, the (n-1)th color data is
-2) Convert to either the color data of the th or nth color data, remove the misjudged color data, and convert the color data of the next stage reading unit to the color data of the erase unit. The data is output to the data converter 55.

In this embodiment, since the area of the reading unit of the color CCD 51 and the area of the erase unit of the edit eraser 5 are different, the data conversion unit 55 converts the color data of the reading unit of the color 〇〇D 51 into the color data of the erase unit of the edit eraser 5. Perform the conversion to This is to prevent image information from being lost. Here, data conversion from a read unit to an erase unit will be explained.

The effective light receiving pixels of the color CD51 used in this example are 2.
250, and the scanning width of the document is 300m. Since the three data of R, G, and B are considered as one set, the image reading pitch is 300÷(2250÷3)-0,4(m
+), and the color of the document can be identified for each pitch. This pitch relates to the main scanning direction, and the reading pitch in the sub-scanning direction changes depending on the scanning speed of the optical system and the charge accumulation time of the COD, but in this embodiment, it is set to 0.4 m. Therefore, the reading unit data for the color CD 51 of this embodiment is data for an area of 0.4 nn x 0.4 m on the original.

Further, in the LED array of the editing eraser 5 used in this embodiment, the LEDs 65 are arranged at a pitch of 1.2-1 in the main scanning direction, as described above. Therefore, the erase unit in the main scanning direction on the photosensitive drum 3 is also 1.2
m pitch. Furthermore, the pitch of each erase unit in the sub-scanning direction on the photoreceptor drum 3 depends on the rotational speed of the photoreceptor drum 3 and the time it takes for the data processing section 70 to rewrite and output data to the LED eraser 5. In this example, it is 1.2 m. Therefore, the erase unit on the photosensitive drum 3 has an area of 1.2 mm x 1.2 nn. On the other hand, as mentioned above, the reading unit of the original with the color CD5J is 9.4 na may occur,
Color data of the scanning unit of the original by color〇〇D51,
It is necessary to convert the color data to the same size as the erase unit by the editing eraser 5. The data converter 55 performs this process.

FIG. 14 schematically shows this data conversion. Color 〇 Reading unit by CD51 is Q, 4+a+
+
lfl, 3×3 COD unit color data is converted into one LED erase unit color data using a predetermined calculation method.

FIG. 15 shows a simplified flow of an example of the calculation method for data conversion shown in FIG. 14.

First, the color data of nine color COD reading units is checked and divided into the following four cases.

(1) When one color data outside of white melon is the most common.

(2) When the color with the most own data can be selected from among the other colors.

(3) In case of own data only.

(4) When there are many colors outside of White Melon, but the color with the most amount cannot be selected, or when there is the most white data, but the color with the most amount of data cannot be selected among other colors.

In case (1), the most common color is stored in the memory section as color data for each LED erase unit.

In the case of (2), the second most common color after white is stored in the memory as color data for each LED erase unit.

In the case of (3), white is the color data for each LED erase unit.

In the case of (4), if the colors are completely different, in such a case there is no problem in determining that it is black to the human eye, so the color data of each LED erase unit is treated as black data, and similar colors are used. If many colors (for example, red and magenta) are mixed, a priority is given in advance and the one with the higher priority is selected.

In the cases (1) to (4) above, the reason why white is given lower priority than other colors is that white can be erased by the photosensitive drum due to the reflected light from the light irradiation on the original, even if it is not forcibly erased. This is because no electrostatic latent image is formed by exposure to light. Conversely, if you give priority to white, especially (1), (
In the cases 2) and (4), the color of the LED erase unit is set to white, which is inconvenient because information on the document is lost.

Specific conversion examples in cases (1) to (4) of 70- in FIG. 15 are shown in FIGS. 16 and 17.

(1) in FIG. 16 is an example in which red is used as the color data for the LED erase unit because red is the most common color data among the color data for nine COD reading units.

(2) in Figure 16 shows that among the color data for nine reading units by COD, red is the second most common color after white, so red is
This is an example of color data in erase units.

(3) of the 1611ffl is the reading unit 9 by CCD.
Since all the color data for each LED erase unit is white, this is an example in which white is used as the color data for each LED erase unit.

(4) in Fig. 16 is an example in which black is used as the color data for the LED erase unit, since the color data for nine units read by the CCD are completely different and do not include similar colors. .

Figure 17 shows that similar colors such as red and magenta are mixed in the color data for 9 reading units by COD, and when red is given a higher priority, red is set as the color data for the LED erase unit. This is an example.

In addition, although we used majority voting to select the most common color, we decided to prioritize (weighted) all the colors as described in the misjudgment removal process.
, you may decide.

FIG. 18(a) is an example of the structure of color data for each LED erase unit in the data conversion section, and is represented by 4-bit data. Bit B3. B2. Bl.

BO is a first developing device 7, a second developing device 8, and a third developing device, respectively.
They are assigned correspondingly to the developing device 9 and the fourth developing device IO. Here, if the bit is "l#", the LED lights up,'
0" means that the LED is off. Specifically, the 18th
This will be explained using the example shown in (b) of the figure. In this example, the LED
The color data for each erase unit is red. The upper two bits are 0# and the lower two bits are "1". In other words, the first
When operating the developing device 7 (yellow toner), since the bit B3 corresponding to the first developing device 7 is 0'',
The electrostatic latent image on the photosensitive drum 3 remains without being erased.
The yellow toner is applied, visualized, and transferred to the transfer belt 15.
transcribed into. Next, the second developing device 8 (magenta toner)
When operating the second developing device 8, the bit B2 corresponding to the second developing device 8 is "0", so the electrostatic latent image on the photosensitive drum 3 is not erased, but the magenta toner is visualized. Multiple transfer is performed on the previously placed yellow toner on the transfer belt 15, creating a red color.

When operating the third developing device 9 and the fourth developing device 10, the corresponding bits Bl and BO are respectively l#, so the electrostatic latent image on the photosensitive drum 3 is erased, and the cyan toner and No black toner.

With this data structure, in the ECP58 program that controls the editing eraser 5,
Edit eraser 5's LE can be erased by simply checking the status of each bit.
It becomes possible to control the D array, improving control speed.

Returning to the explanation of the data processing section 70 in FIG. 11 again.

In this embodiment, the data converter 55 processes every three lines. ■The data of the 2nd line and the 2nd line are stored in the line memory RAMs 213 and 214, respectively, and when the data of the 3rd line comes in, synchronization is achieved by a synchronization signal (not shown), and the latches 215a to 2
15c, the selector 216 selects 3 pieces of color data for each line, for a total of 9 pieces of color data, and the decoder 217 selects each color data from yellow, magenta, cyan, red, and green in the figure from top to bottom. , black, or white, the gates 218a to 218a correspond to these colors.
Output to 218g. Each gate 218a to 218g is
The data counting sections 219a to 219g are opened by the signal output from the decoder 217 and the data counting pulse inputted in synchronization with the signal output, and therefore the data counting sections 219a to 219g each have 9
Count the colors included in the data. Although not shown, when the counting of nine colors is completed, the data counting sections 219a to 219g are each reset to prepare for the next counting.

The selector 220 first selects the data count section 219a.
The values of ~219d (yellow, magenta, cyan, red) are sent to the next pitch conversion ROM 221, the converted values are held in the latch 222 while referring to the table therein, and then the data count units 2198 to 219g The values of (green, black, white) are sent to the pitch conversion ROM 221, and by referring to the values held in the latch 222 and the table in the ROM 221, one color is selected, converted, and held in the latch 223. The data latched by the latch 223 is color data for each erase unit, and is sent to the color limitation detection section 57 in parallel with the memory section 56, as shown in FIG. 11(b).

The memory unit 56 stores the color data in erase units from the data conversion unit 55 in the RAM 227 in accordance with the address signal created by the address creation unit 225. The data from the data converter 55 and the address signal from the address generator 225 are sent to the buffer 224 and the buffer 2, respectively.
26 to the RAM 227.

The color limitation detecting section 57 is provided to check and store the contents of the output data from the data converting section 55 in the memory section 56 in parallel with storing the output data in the memory section 56. The purpose of this is, for example, if the original color is only black, development operations are performed for each of yellow, magenta, and cyan toners, even though the developing devices are not used. In other words, the editing eraser 5, each electrostatic latent image is erased, which would cause a huge waste of time.
This is to omit the development of each color of cyan and perform only the development of black, thereby preventing loss from occurring.

FIG. 19 shows a schematic block diagram of the color limitation detection section 57, and the structure and operation of the color limitation detection section 57 will be explained.

B3 in the diagram. B2. Bl and BO are each bit of the color data of the LED erase unit explained in FIG. In addition, the data count pulse is a pulse that is output in synchronization with data conversion for each LED erase unit, and is a pulse that is output at the gate (g
l), (g2), (g3), and (g4) are input together with 83~BO, and the contents of 83~BO (“0” or “1”)
Accordingly, the next stage data counting section (hi), (h2)
, (h3), and (h4), it is determined whether or not to output count pulses. game) (gl)~(g4) is B3~
A data count pulse is output to the data count section only when the content of BO is "0". Taking the case where the color data is yellow as an example, the data is "0", "1#""l", and 'l# in order from the most significant bit, so the gate (
gl) is open. Therefore, a count pulse is output to the data count section (hl). The same applies to other cases, and for each color data of the LED erase unit, the data count section (h
1), (h2), (h3), and (h4) counting operations are performed.

If you perform the above operation for one document, the data count section (
In hl), (h2), (h3), and (h4), data necessary and unnecessary for the operation of the developing devices 7 to 10 is accumulated for one document, respectively.

After the reading of one document is completed, a signal is sent from the ECP 58 to the data selector i, and the data count sections (hl) and (h
2) The contents of (h3) and (h4) can be selectively read out, and if there is a count value of zero, the developing device of the corresponding color should not be used. Color-limited detection becomes possible.

Note that in this color limitation, if the count value is not zero, but is a value that can be ignored compared to the maximum value, it may be ignored.

This color-limited detection eliminates the need to operate a developing device that does not need to operate, thereby improving the image forming speed.

Further, one screen information of the color data of the document stored in the memory unit 56 is stored in buffers 228 and 229 by the microcomputer CPU 232 in the ECP 58 during the development operation.
The data is read out from the RAM 227 of the memory unit 56 via the memory unit 56 and output to the edit eraser controller 59 that controls the edit eraser 5.

The processing of reading the color information of the document using COD, the processing of storing it in the memory 227, and the color limitation detection processing described above are performed by hardware, thereby reducing the processing time.

Image forming operation FIG. 20 is a flowchart of the image forming operation.

First, the document is irradiated with a lamp to form an electrostatic latent image on the photoreceptor drum through the lens and mirror (formation of an electrostatic latent image by an analog process) (step #5), as shown in FIG. Based on the data stored in the memory in step #4 of 70- of original reading, unnecessary latent images are erased by the editing eraser 5 in correspondence with the developing color to be currently operated (step #6); With the currently selected developing device!・Visualization was performed using
Step #7), and transferring the toner image onto the transfer belt (Step #8). Additionally, the processes in steps #5 to #8 are repeated for each color toner, and when the process is completed for all colors (YES in step #9), the process is transferred to paper (step #10), and the melting theorem is satisfied. is applied (step #11), and the paper is ejected (step #12).

In this embodiment, normally the first developing device 7 (yellow), the second developing device 8 (magenta), and the third developing device 9 (cyan)
After each of the developing devices 10 and 10 (black) performs the processing in steps #5 to #8, the process moves to step #lO, and a color copying operation is realized.

FIG. 21 explains the color copying operation using an example.

FIG. 21(a) is an example of a color original 50. As shown in FIG. It consists of a black rectangle, a yellow square, a red circle, and a green triangle on a white background.

These are separated and separated from each other.

This original 50 is placed on the original table glass 26, and scanning for reading the original is executed. The reflected light from the original is C
The light enters the color CCD 51 through the CD lens 51a. The above-mentioned processing is performed on the output from the color 〇〇D 51, and the black, yellow, red, green, and white of each color-coded portion of the original image is determined.

A first scan is performed on the document (a), and the photosensitive drum 3 is exposed. Prior to this exposure, the photoreceptor drum 3 is uniformly charged to a predetermined polarity by a charging charger 4, and by exposure, an electrostatic latent image of the entire document is formed on the photoreceptor drum 3. This is shown in (bl) of FIG. 21 in this embodiment: yellow (y), magenta (m), cyan (c), black (
Since the developing devices are selected in the order of the toner colors b) and developed, only the electrostatic latent image containing the yellow component is left in the first time. The latent image in the rectangular portion is erased by the editing eraser 5. This situation is shown in Figure 21 (cl
) is shown. Note that since red is created by a mixture of yellow and magenta toners, and green is created by a mixture of yellow and cyan toners, the electrostatic latent images in the red circular portion and the green triangular portion are not erased.

Then, this yellow latent image passes through the first developing device 7, and the yellow toner is deposited on the photosensitive drum 3, as shown in FIG.
It is visualized as in di). This photosensitive drum 3
The upper yellow toner image is transferred to the transfer bell (15). This is shown in FIG. 21 (el). The second time is also the first
The same action as the first time is repeated. An electrostatic latent image is formed on the photoreceptor drum 3 from the document Ca) ((b2 in FIG. 21).
)) The electrostatic latent images in the black rectangular area, yellow square area, and green triangular area that do not require development with magenta toner are erased by the editing eraser 5, leaving only the latent image in the red circular area ( (c2) in Figure 821). Then, this is visualized by the magenta toner of the second developing device 8 ((d2) in FIG. 21), and the magenta toner is transferred onto the transfer belt 15 on which the yellow toner image was transferred in the first time. ((e2) in Figure 21). As shown in (e2) of FIG. 21, the circular area where yellow and magenta toners are mixed becomes red.

The same operation as above is repeated for the third time as well.

An electrostatic latent image is formed on the photoreceptor drum 3 from the document (a) ((b3) in FIG. 21), and includes a black rectangular area, a yellow square area, and a red circular area that do not require development with cyan toner. The electrostatic latent image is erased by the editing eraser 5, leaving only the green triangular latent image ((c3) in FIG. 21). Then, this is visualized by the cyan toner of the third developing device 9 ((d3) in FIG. 21),
Cyan toner is transferred onto the transfer belt 15 onto which the first yellow toner image and the second magenta toner image have been transferred ((e3) in Figure 21) - (e3) in Figure 21
As shown in , the triangular area where the yellow and cyan toners are mixed becomes green.

The same operation as above is repeated for the fourth time as well.

An electrostatic latent image is formed on the photoreceptor drum 3 from the document (a) ((b4) in FIG. 21), and a yellow square part, a red circular part, and a green triangular part that do not require development with black toner are formed on the photoreceptor drum 3 ((b4) in FIG. 21). The electrostatic latent image is erased by the editing eraser 5, leaving only the black rectangular latent image (21st
(c4) in the figure). This is visualized by the black toner of the fourth developing device IO (Fig. 21 (d4)).
, the black toner is transferred onto the transfer bell (15) onto which the first yellow toner image, the second magenta toner image, and the third cyan toner image have been transferred ((e4) in FIG. 21).

In this way, the first to fourth operations are performed, and a toner image corresponding to the color of the original image is formed on the transfer belt 15. This is transferred onto the fed paper (FIG. 21(f)), and the actual color of the original is reproduced on the paper.

Note that marks are attached to the transfer belt 15, which are detected by a sensor (not shown) so that the toners of each color are transferred onto the transfer belt 15 without misalignment.

The present invention is not limited to the above embodiments, and various changes and modifications can be made within the scope of the claims.

(Effects of the Invention) According to the multicolor image forming apparatus according to the present invention, single color data isolated between one continuous color data and another continuous color data on the color CCD used for document reading. If there is, by converting it into one of the continuous color data mentioned above, it eliminates the misjudgment of color at the transition of the color of the original, which was a drawback of conventional color CDs, and eliminates color ghosts. It is possible to prevent this occurrence and accurately reproduce the color information of the original.

Further, since there is no need to operate developing devices for unnecessary colors, time and expense can be saved.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a copying machine to which the present invention can be applied. FIG. 2 is a schematic diagram of the LED array eraser. FIG. 3 is a plan view of an example of the operation panel of the copying machine. FIG. 4 is a schematic control block diagram of the copying machine. FIG. 5 is a flowchart of document reading. FIG. 6 is a diagram showing an example of output characteristics according to color of the COD sensor. FIG. 7 is a schematic diagram showing the principle of occurrence of color misjudgment by the COD sensor. FIG. 8 is a simplified flowchart of the erroneous judgment removal process according to the present invention. FIG. 9 and FIG. 10 are diagrams showing the state of the erroneous judgment removal process according to the present invention. FIGS. 11(a) and 11(b) are schematic block diagrams of the data processing section. FIG. 12 is a diagram showing an example of color COD output. FIG. 13 is a diagram showing an example of encoding of output data. FIG. 14 is a schematic diagram of conversion from read unit data to erase unit data in the data converter. FIG. 15 is a simplified 70-chart of data conversion. 16 and 17 are specific examples of data conversion according to FIG. 15. FIG. 18(a) is a diagram showing the structure of color data for each LED erase unit in the data converter. FIG. 18(b) is a diagram showing the structure of color data for red. FIG. 19 is a schematic block diagram of the color detection and limitation section. FIG. 20 is a 70-chart of image formation. FIG. 21 is a diagram showing the progress of a color copying operation. l... Copying machine, 3... Photosensitive drum, 5... Editing eraser, 7... First developing device, 8... Second developing device, 9... Third developing device, lO ...Fourth developing device,
15... Transfer belt, 29... Lamp, 49...
Fixing device, 50... Original, 51... Color CCD,
58...ECPL 70...Data processing section, 80.
...Misjudgment removal processing unit, 100...Paper patent applicant Minolta Camera Co., Ltd. Representative Patent Attorney Yasushi Yama et al. Figure 10 Figure 12 Figure 15 Figure 14 Figure 14 CCD tG cut sheep fl: 0.4 x 0.4 m
m / dotLED 7 Rayi L, -Su Hayabusa (fL:
1.2X+, 2 mm/dat Fig. 16 (a) Fig. 17 Fig. 18 (b) Fig. 19

Claims (1)

[Claims] (1) The original is irradiated with light, and the reflected light is exposed to the uniformly charged surface of the photoreceptor to form an electrostatic latent image corresponding to the original image, while the original image is colored by the original reading means. Based on the obtained image data for each color, the photoreceptor on which the electrostatic latent image has been formed is selectively irradiated with light by an erase means, leaving the area to be developed with toner. After erasing the other parts, the remaining electrostatic latent image is developed using toner of the corresponding color, and the process of transferring the developed toner image to the intermediate transfer medium is repeated at least once, and then the intermediate transfer medium is In a multicolor image forming apparatus that forms a multicolor toner image on a paper and then transfers it to paper and fixes it to form a multicolor image, the color data read by the original reading means is input, and the color data is input to the original reading means. If single third color data is detected between continuous first color data and continuous second color data, this third color data is replaced with the first or second color data. What is claimed is: 1. A multicolor image forming apparatus comprising: data correction means for converting the data into either one of the above and outputting the data, and using color data output from the data correction means as image data.