JPS6136764A - Multicolor image forming method - Google Patents

Abstract

PURPOSE:To form good multicolor images by sticking a toner to the whole of an electrostatic latent image in a unit with one or more developing devices and sticking the toner to electrostatic latent image parts having a high surface potential with other developing devices if the electrostatic latent image should be developed in colors different from one another and has a difference of surface potential. CONSTITUTION:The reflected light from an original is reflected on scanning mirrors 8- 10 and passes a focusing lens 11 and is reflected on another mirror 12 and reaches a photosensitive body 1 to focus the original image. This electrostatic latent image consists of red, green, blue, and black latent images corresponding to colors of the picture on the original. Though a part of the light reaching the photosensitive body 1 is transmitted through a half mirror 14, the light reflected on the half mirror 14 passes another focusing lens 15 and reaches a color scanner 16. The original image is focused on the color scanner 16 to discriminate individual colors of the original picture. The output from a CCD17 is inputted to a CPU18, and the proportion of each color toner which should be stuck to an electrostatic latent image part corresponding to the color designating unit is operated by the CPU18, thereby improving the quality of reproduced multicolor images.

Description

[Detailed description of the invention] Ai Toyobunmi The present invention relates to a multicolor image forming method.

In conventional multicolor image forming methods, one latent image carrier is rotated multiple times to obtain a visible image of a predetermined color each time, or multiple latent image carriers are used and each A common method is to obtain visible images of predetermined colors and sequentially transfer them to the same transfer material. However, if the latent image carrier is rotated multiple times, it takes time to complete the entire image forming process, and conversely, if multiple latent image carriers are used, the cost of the device increases and the device becomes large. cannot escape the drawbacks of becoming

Therefore, after forming an electrostatic latent image on a latent image carrier, the latent image is developed with toner of one or more colors for each color specified unit to obtain a multicolor image. Using a carrier,
Furthermore, a multicolor image can be formed in a short time by rotating this device once. However, when implementing this method, when electrostatic latent images to be developed in different colors coexist in the same color designation unit, the problem arises as to how to visualize these images. One method would be to visualize this color designated unit in a color intermediate between the colors to be developed, but this would reduce the sharpness of the completed multicolor image. Another method is to improve sharpness by making the color designation unit extremely small and increasing the density of the unit. However, if this method is adopted, the cost of the developing device will increase.

There is a risk that the image forming speed will decrease.

(2) The present invention provides a multicolor image forming method that includes the steps of forming an electrostatic latent image on a latent image carrier and developing the latent image with toner of one or more colors for each color designated unit. It is an object of the present invention to provide a new method that can easily solve the above-mentioned problems.

In the present invention, when there are electrostatic latent images with different surface potentials to be developed in different colors in the same color designated unit, the entire electrostatic latent image in the unit is developed using at least one developing device. The above object is achieved by adopting a configuration in which the toner is attached to the electrostatic latent image portion having a high surface potential and the toner is attached to only the electrostatic latent image portion having a high surface potential using at least one other developing device.

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

FIG. 1 shows a copying machine as an example of an image forming apparatus that implements the method according to the present invention. First, we will first explain its configuration and the basic operating mode that forms the basis of the present invention in which a multicolor image is created by this copying machine. We will clarify about this.

In the illustrated copying machine, the latent image carrier is constructed as a photoreceptor 1 formed in the shape of an endless belt, and this photoreceptor 1 is wound around three rollers 2, 3, 4 and driven in six directions of arrows. The photoreceptor 1 having the 9 parts has, for example, panchromatic spectral sensitivity. pc (organic photoconductor)
A photoreceptor containing the following can be used as appropriate.

A contact glass 5 is fixedly installed in the upper part of the copying machine, and an original 6 to be copied is placed on the contact glass 5.

The illustrated copying machine can copy multicolor images of any color, but in order to clarify the basic operation of the method according to the present invention, first, as shown in FIG. 2(a), a red image R1 a green image A case will be described in which a document 6 in which a blue image B, a blue image B, and a black image BL are formed on a white background W is to be copied.

During the copying operation, the light 11i7 located below the contact glass 5 illuminates the original 6 while scanning, as in a normal copying machine, and the reflected light illuminates the mirror 8, which also scans.
9. It is reflected by 10, passes through the imaging lens 11, and passes through the other mirror 1.
2 and reaches the photoreceptor 1, where an original image is formed. At this time, the photoreceptor 1 is driven in the six directions of the arrows and is uniformly charged to a predetermined polarity by the charger 13, so that an electrostatic latent image corresponding to the original image is formed on the photoreceptor 1 by the exposure. (In this example, the charging polarity of the photoreceptor 1 is negative, and the surface potential after being charged by the charger 13 is -700V).

The electrostatic latent images formed on the photoreceptor 1 are images R and G on the original 6, as schematically shown in FIG. 2(c).

B, red latent image R1, green latent image G1, corresponding to BL. Blue latent image B
1, and a black latent image BLI.

On the other hand, there is a half mirror in the optical path from the original 6 to the photoreceptor 1.
14 is interposed, and as mentioned above, the light that reaches the photoreceptor 1 passes through the half mirror 14, but the light reflected here passes through another imaging lens 15 and reaches the color scanner 16. The original image is imaged, and each color of the original image is determined.

As the color scanner 16, any suitable type of scanner known per se can be used, but in the illustrated example, a CCD 17 having a large number of light receiving sections arranged in a direction perpendicular to the plane of the paper of FIG. A color scanner is used which has three types of filters 17a, a red filter, a green filter, and a blue filter, superimposed on each of the light receiving sections, and the filters are arranged alternately in the above-mentioned order. The arrangement relationship between the CCD 17 and the photoreceptor 1 is schematically shown in FIGS. 2(b) and 2(c). This is a color scanner that uses three CCDs and superimposes red, green, and blue filters on the light receiving area of each CCD. , C
A scanner using a 1x sensor may be used instead of the OD, and when a 1x sensor is used, the imaging lens 15 can be omitted.

When light from the original 6 enters the color scanner 16 described above, the light selectively passes through red, green, and blue filters depending on its properties, and the output from the CCD 17 is sent to the CPU.
18 (FIG. 2(b)), the document 6 is divided into minute parts (reading units) in a manner known per se, and the color of each part is determined, and as described later, the electrostatic latent image is determined. At the time of visualization, the CPU 18 calculates the ratio of toner of each color to be applied to the electrostatic latent image portion corresponding to the color specified unit to reproduce the original image, and this information is stored in the memory 19 (second section). 2 (b)). At this time, if processing such as color correction (masking) and background processing (UCR) is performed by the CPU, it is advantageous because the image quality of the reproduced multicolor image can be improved.

On the other hand, as shown in FIG. 1, two or more (four in this example, four) developing units 20, 20a, 20b, and 20c are located around the photoreceptor 1 on the downstream side of the exposure position. It is located in The developing device shown here is manufactured by Japanese Patent Application Laid-Open No. 1986-
This is an application of the so-called LIST type developer disclosed in Japanese Patent Laid-Open No. 84955 or Japanese Patent Laid-Open No. 58-66954, and each developer is placed opposite to the photoreceptor 1 and rotated counterclockwise. Donor rollers 21, 21a, 21
b, 21C and the doctor 2 placed opposite each donor roller
2° 22a, 22b, 22c and a multi-stylus 23° 23a, 23b, 23c, respectively. The hopper of the third developing device 20b stores magenta toner MT, the hopper of the third developing device 20b stores cyan toner CT, and the hopper of the fourth and final developing device 20c stores black toner BLT. Photoreceptor 1
A positioning plate 25 is disposed on the opposite side of the donor roller from the photoreceptor 1 to the donor roller 21.
, 21a, 21b, and 21c are regulated.

As will be described later, the red latent image R1 formed on the photoreceptor 1 is formed by the yellow toner YT of the first developing device 20 and the second developing device 20a.
The green latent image Gl is visualized as a red color by the magenta toner MT of the first developer 20 and the cyan toner CT of the third developer 20b. The latent image Bl is made visible in blue by the cyan toner CT of the third developing device 20b and the magenta toner MT of the second developing device 20a, and finally the Kuroshio image BLI is made visible by the black toner BLT of the fourth developing device 20c. Imaged.

Each donor roller consists of a conductive rubber roller with a diameter of 36 nm, for example, and each multi-stylus 23, 23&, 23
b and 23c are a number of electrodes made of, for example, nickel plates arranged in a staggered manner in the direction transverse to the rotational direction of the donor roller or the running direction A of the photoreceptor 1, as illustrated in FIGS. 3 and 4. It consists of a needle 26 and a fixing material 27 made of, for example, epoxy resin, which fixes the needle.

FIG. 2(d) shows the relationship between each electrode needle 26 of the first developing device 20 and the donor roller 21, and FIG. 2(f) shows the relationship between the second developing device 20
Although the relationship between the electrode needle 26 and the donor roller 21a in FIG.

The doctor 22, 22a, 22b, 22c has the photoreceptor 1.
A voltage of, for example, −100 V, which has the same polarity as the charged polarity of
A negative charge is injected into the toner carried by t 2 l b + 21 c and sent out from each hopper,
The toner is negatively charged. The doctor also serves to regulate the thickness of a layer of toner on the donor roller fed from the hopper to a predetermined thickness of, for example, about 30 microns.

After the toner layer on each donor roller has been charged as described above, each multi-stylus 23, 23a, 23b, 23c is applied to the area to which the toner is to be applied, more precisely to the electrostatic latent image, as described below. A charge having a polarity opposite to that of the latent image, that is, a positive polarity, is injected only into a portion of the toner layer that includes a portion corresponding to the latent image, and the charged polarity is converted to positive. In the illustrated example, the electrostatic latent image on the photoreceptor 1 is first developed by the first developing device 20.
The state at this time will be clarified. First of all
The information about which part of the latent image the yellow toner YT of the developing device 20 should be attached to and in what ratio with respect to toners of other colors, that is, the yellow information, is called up, and the positive pulse voltage based on this information is first set. The voltage is selectively applied to the electrode needle 26 of the first developing device 20 via the driver 28 (FIG. 2(d)).

Therefore, the amount of charge of the toner passing under the electrode needle to which voltage is applied is converted to positive polarity. In this way, the electrode needle 2
In one or more units (these are called color designation units) determined by the width W of 6 (Fig. 3), the charged polarity of one layer of toner becomes positive, and a charge pattern corresponding to yellow information 1 is formed (second (d)), in this example, Fig. 2(d)
In particular, voltage is applied to two electrode needles marked 126 and one electrode needle also marked 226, and four color designation units CUI of the toner layer passing under the electrode needle 126 and the electrode needle 226 are also applied. One color specification unit C of one layer of toner passing under
U2 is reversed to positive polarity, and its charge amount is +10μc/g
That's about it. The other toner layers remain negative and do not reverse.

As described above, a layer of positively or negatively charged toner faces the photoreceptor 1 as the donor roller 21 rotates, and comes into sliding contact with or approaches the surface of the photoreceptor. At this time, the single layer of positively charged toner corresponds to the red tide image R1 and the line latent image G1, and the toner on the donor roller charged to the opposite polarity to these latent images electrostatically transfers to these latent images, and the latent image R1 , Gl are visualized by yellow toner (FIG. 2(e)), in other words.

As shown with the 4m chain line in FIG. 2(c), a latent image R1 to be visualized in the first layer of positively charged toner within the range of color designation units CUI and CU2 described above.゜G1 is included in each electrode needle 126, 2 in advance based on the yellow information so that only one layer of the toner in the smallest color specification unit has positive polarity.
A voltage is applied to 26. Also, during development, the color specification unit C
Toners other than UI and CU2 remain negatively charged, so
It does not adhere to the latent images Bl and BLI, which should not be visualized, and development is performed through the cooperative action of positive toner and negative latent images, so that the toner of the positively charged color specified unit is not attached. Of these, toner in portions that do not match the latent images R1 and Gl does not adhere to these latent images.

Call up the magenta information in exactly the same way as shown in Figure 2(f).
As shown in FIG. 2, a pulse voltage is selectively applied to the electrode needles of the second developing device 20a (in this case, electrode needles 126 and 326),
The toner layer of the four color specification units CUI that can visualize the red tide image R1 is, for example, +15 μc/g, and the toner layer of the three color specification units CU3 that can visualize the blue latent image Bl is, for example, +10 μc/g. Magenta toner MT is deposited on both charged latent images R1 and Bl in an amount determined by the surface potential thereof and the amount of charge of the toner. As a result, the previous yellow toner YT and the current magenta toner MT adhere to the red tide image R1, forming a red visible image R2 (see Figure 2 (g).
)) In the same manner, the third developing device 20b applies cyan toner CT to the line latent image Gl and the blue latent image BI from above the yellow toner and magenta toner that have already adhered, respectively, to form a visible green color. 1. Next, a fourth developer 20C attaches black toner BLT to the black latent image BLL to form a multicolor image that is the same as or similar to the images R, G, B, and BL of the original 6. obtain. This multicolor image is stored in the paper feed section 29
The images are transferred all at once onto the transfer paper 30 fed from the transfer paper 30 (FIG. 1) by the discharge action of the transfer charger 31. Transfer paper 30
After being separated from the photoreceptor 1, it is sent to the fixing device @32,
Here, the multicolor image is fixed and discharged outside the machine. After the visible image has been transferred, the photoreceptor portion is subjected to a static eliminating action by a static eliminating charger 33, and residual toner is removed by a cleaning device 134.

The method described above reads the original image in predetermined reading units, selectively applies voltage to the electrode needles based on the color information, and creates one or more electrostatic latent images in each predetermined color designated unit. It is developed using colored toners, and it is possible to obtain a multicolor image with one rotation of the photoreceptor. Moreover, since development is performed by the cooperation of the toner charge and the electrostatic latent image of the opposite polarity, a charge pattern corresponding to the visible image can be formed using only the multi-stylus, and a visible image can be created using only the toner charge. Compared to the method of obtaining
ws, thereby reducing the cost of the multi-stylus and increasing the image forming speed. Instead of using yellow, magenta, and cyan toners, it is also possible to use red, blue, green, yellow, and other toners to obtain a visible image without overlapping different color toners.

By the way, as long as the images of each color on the document are layered at a predetermined distance or more from each other as shown in FIG. 2(a), a multicolor image can be obtained without any problem using only the above-mentioned basic operations. However, if the images are close to each other or in contact with each other, one color specification unit may contain electrostatic latent images that should be visualized with toner of different colors. Movement alone will reduce the sharpness of the completed multicolor image.

For example, consider the case of copying a document portion 6a in which a round red image R is formed on a yellow background, that is, a yellow image Y, as shown in FIG. 5(a). The electrostatic latent image on the photoreceptor 1 obtained from this portion 6a is shown in FIG.
) as shown below. The surface potential of the red tide image R1 corresponding to the red image R is, for example, about -400V, and the surface potential of the yellow latent image Y1 corresponding to the surrounding yellow □ image Y is, for example, about -1200V. Further, as shown in FIG. 5(a) by dividing the part 6a into 16 equal parts, pXp (for example, p=0.5m
+), the color is determined for each reading unit, and the latent image shown in Fig. 5(b) is converted to PXP (for example, P; P; however, P=P does not necessarily have to be the case). ,
It is assumed that the latent image is visualized in each color specified unit (P may be an integral multiple of P, etc.) (Therefore, the width W of each electrode needle 26 shown in FIG. 3 is also is 0.5 m
). Also, for convenience of explanation, each reading unit and each color designation unit are marked with 1 as shown in FIG. 5<a) to (d).
16 to 16 to identify these.

As can be seen from FIG. 5(a), the yellow image Y and the red latent image R
are in contact, so the reading unit is 2゜3.5, 8, 9
, 12, 14, and 15, a red image R and a yellow image Y coexist, and therefore, these reading units are judged to be orange, which is between red and yellow, and the overall judgment state is shown in Fig. 5 (c). (Y indicates yellow, O indicates orange, and R indicates red). Correspondingly, as shown in FIG. 5(b), the color designation units are 2, 3.5, 8, 9, 12°14.
15, a red tide image R1 and a yellow latent image Y1 coexist.

Depending on the above-described color determination and the level of surface potential of the electrostatic latent image, the latent image is visualized for each color designated unit in the manner described above in connection with FIGS. 1 and 2, A visible image as shown in FIG. 5(d) is obtained.

The state of this visible image is not only based on the color judgment state shown in FIG. 5(b), but also depends on the surface potential of the latent image, so the yellow part Y2 shown by the roughest diagonal line. Next, there is a thin orange part 02 indicated by coarse diagonal lines, a dark orange part 022 indicated by the finest diagonal lines, and a red part R indicated by double diagonal lines.
2, but such a multicolor image cannot be said to be a faithful reproduction of the red image R and yellow image Y of the document portion 6a (the outline of the red visible image becomes unclear).

In order to eliminate the above drawbacks, the reading unit and color specification unit of the manuscript portion 6a should be made smaller, for example, P and P of both units should be 0.25 degrees or less, and the manuscript portion 6a should be divided into, for example, 64 portions. It is possible to read the latent image and visualize it in units of the same size.1 However, if this method is used, the cost of the multi-stylus and its driver will be high, and the image formation time will be increased.

Therefore, in the configuration according to the present invention, in addition to the basic operations described above, when latent images to be visualized in different colors coexist in one reading or color designation unit, the following measures are taken.

That is, as shown in FIG. 6(a), for convenience of explanation, it is assumed here that the same original as shown in FIG. 5 is copied, the reading unit is pXp (p=o, 5I), and the color specification unit is PXP. (P=0.5-).

Figure 6 (b), (c,) are Figure 5 (b), (c)
shows exactly the same condition. The image of the document portion 6a is reproduced by the yellow L-Q YT of the first developing device 20 shown in FIG. 1 and the magenta toner MT of the second developing device 20a, but the image shown in FIG. 6(b) The electrostatic latent image is transferred to the first developing device 20.
The yellow toner YT on the donor roller 21
is attached to both the red tide image R1 and the yellow latent image Y. In other words, the yellow toner YT on the donor roller 21 corresponding to color designation units 1 to 16 shown in FIG. It is charged to such a high charge amount (in this example, this is assumed to be +15 μC7 g) that it adheres to the red tide image R1 of 1400 square meters. The charging state of the toner on the donor roller corresponding to each color specified unit at that time is shown in FIG.
It means that it is g.

FIG. 7 shows a state in which the relationship between the charge amount [μc/gl] of the toner and the density [LD] of the visible image formed by the toner changes depending on the surface potential on the photoreceptor. When toner is charged to +15μc/g, -2
The yellow latent image of the surface potential of 00V is at the concentration of Dl, and -40
The red tide image with a surface potential of 0■ is visualized at a density of D2. The state of the yellow visible image formed in this way is shown in FIG. 6(e), where the red tide image part turns deep yellow Y2,
The yellow latent image around it is pale yellow Y22.

Next, the latent image passes through the second developing device 20a, and magenta toner adheres to a predetermined portion of the latent image.

In the second developing device, the toner on the donor roller corresponding to the reading units determined to be red and orange is positively charged, but at this time, the magenta toner M on the donor roller 2ia
T is an amount of charge such that it adheres to the red tide image R1 with a high surface potential (on the negative side in this example) but does not adhere to the yellow latent image Y1 with a low surface potential (also on the negative side), for example +7 ，
It is charged to a charge amount of 5 μc/g. Figure 6(f)
indicates the charging state of the toner corresponding to each color designated unit, and 7.5 indicates that the toner is charged to +7.5 μc/g. Also, hue localization [1,4°13.
Since 16 does not include a red tide image, the toner at this potential is not positively charged, and the "-" written in these units indicates that the toner remains negatively charged. The magenta toner of such a donor roller 1- adheres only to the high red tide image on one surface, overlapping the yellow toner, and does not adhere to the yellow latent image.

As mentioned above, the red tide image is visualized by superimposing toner toner YT and magenta toner MT, so it becomes a red visible image, and the yellow latent image around it is visualized as yellow only by yellow toner YT. The two visible images are clearly separated (Fig. 6(g)).

In this way, a multicolor image with high sharpness can be obtained without making the color specification unit particularly small.

To change the amount of charge on the toner on the donor roller, change the height and/or pulse voltage applied to the electrode needle of the multi-stylus.
Alternatively, the pulse width (time) may be adjusted. That is, as shown in FIG. 8, if the initial charge amount on the donor roller injected by the doctor is -15μc/g, in order to charge it to +15μc/g, 0.3i+ is required.
If the pulse width is AEC, it is sufficient to apply a pulse voltage of +150V to the electrode needle, and to charge the toner to +7.5μc/H with a pulse voltage of the same pulse width, +75V is required.
A pulse voltage of V may be applied.

In the above method, when electrostatic latent images with different surface potentials to be developed in different colors coexist in the same color specified unit, the entire electrostatic latent image in the unit is processed using at least one developing device. This is because toner is applied to only the electrostatic latent image portion having a high surface potential using at least one other developing device.

Original images of any appropriate color other than the red and yellow original images can also be copied according to this method. For example, a yellow image and a recorded image (reproduced with yellow toner and cyan toner)
are adjacent to each other, a cyan image is adjacent to a green image, a cyan image is adjacent to a blue image (also reproduced with cyan toner and magenta toner), a magenta image is reproduced with a red image (also reproduced using magenta toner) It can be widely applied when a magenta color image and a blue image are adjacent to each other (reproduced with yellow toner), or when a blue image is adjacent to a magenta color image. In the example shown here, one image is reproduced with toner of a primary color and the other image is reproduced with toner of that primary color and secondary color. Even when the density of one image is lower than the sensitivity of the other image, such as when a black image is formed on the background, there is a difference in the surface potential of the latent image formed from these images, and therefore, there is a difference in the surface potential of the latent image. This image can be reproduced according to the method described above.

In the image forming apparatus shown in FIG. 1, an electrostatic latent image is formed on the photoreceptor by illuminating the original with an analog optical system, but the present invention can also be used when forming a latent image digitally instead. It can be applied as is. For example, after uniformly charging the photoreceptor 1 to a predetermined value (for example, -700V) by using a light emitting diode array (LED array) having a large number of light emitting parts about 127 m long and placed opposite to the photoreceptor 1, as shown in FIG. (
The light emitting part of the LED array corresponding to the yellow latent image Y1 shown in b) is caused to emit light based on the image signal to form a yellow latent image Y with a surface potential of, for example, -200V, and the light emitting part corresponding to the red tide image is made to emit light based on the image signal. A highly sharp multicolor image can be obtained by forming a red tide image with a surface potential of -700 V, for example, without emitting light, and otherwise in exactly the same manner as the method described above. It goes without saying that images of other colors as exemplified above can also be reproduced by this method.

Even when a latent image is formed by a multi-stylus on a latent image carrier including a photoreceptor or dielectric instead of an LED array, the present invention can be applied to an image signal containing one-color information by adjusting the surface potential of the latent image. When forming a latent image based on the image, it is not necessarily necessary to read the original image with a color scanner and determine its color as in the embodiment shown in FIG.

Furthermore, in the above embodiments, by changing the amount of charge of the toner on the donor roller, the toner was controlled to adhere to or not adhere to the latent image, but by adjusting the bias voltage applied to each donor roller, the same It is also possible to obtain results.

In this case, as shown in FIG. 6, the red tide image R1 and the yellow latent image Y1 exist in the same color designated unit.
V, yellow toner is attached to both latent images, and the donor roller 21a of the second developing device 20a is supplied with, for example, -200V.
If a developing operation is performed by applying a bias voltage of , even if the same level of charge, for example +15 μc/g, is applied to the predetermined toner on each donor roller 21, 21a by the electrode needle.

The same results as shown in FIG. 6 can be obtained. The same applies when reproducing other colors.

The developing device used in the method according to the present invention is not necessarily the first one.
In addition to the LIST type developing device shown in the figure, it is also possible to use a developing device that can deliver toner only to necessary areas.

Further, the number of developing devices used may be the same as the number of colors to be reproduced, and the black latent image may be visualized by superimposing yellow, magenta, and cyan toners. Furthermore, it is clear that the present invention can also be applied when forming a multicolor image by using red toner, blue toner, green toner, and black toner in the necessary amounts instead of yellow, magenta, and cyan toners. .

According to the present invention, it has become possible not only to obtain multicolor images in a short time and with a small-sized apparatus, but also to form images with excellent sharpness.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of a copying machine that implements the method according to the present invention, and FIGS. 2(a) to (g) show multicolor images formed by the copying machine shown in FIG. 1. A schematic explanatory diagram showing the procedure, Figure 3 is a bottom view of the multi-stylus, Figure 4 is its side view, and Figures 5 (a) to (d) are diagrams when different color latent images coexist in the same color specification unit. 6(a) to 6(g) are explanatory diagrams showing an example of the method according to the present invention. FIG. 7 is an explanatory diagram illustrating the inconvenience. Figure 8 is a graph showing the relationship between the pulse voltage applied to the electrode needle of the multi-stylus and the amount of charge on the toner. 20.20a, 20b, 20cm developer YT, MT, C
T... Toner Figure 1 JI Jl Figure 2 Figure 3 Figure 5 ((F) (b) 6th (G) (c) (e) (7) (b) (d) <g>

Claims (1)

[Claims] The process includes a step of forming an electrostatic latent image on a latent image carrier, and a step of developing the latent image with toner of one or more colors for each color designated unit, and the step of developing the latent image with toner of one or more colors in the same color designated unit. When there is an electrostatic latent image with a difference in surface potential to be developed, at least one developer applies toner to the entire electrostatic latent image within the unit, and at least one other developer A multicolor image forming method characterized by attaching toner only to an electrostatic latent image portion with a high surface potential.