JPH0441823B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a multicolor image forming method using a photoreceptor suitable for forming multicolor images by electrophotography. [Prior Art] Many methods and devices used therefor have been proposed for the purpose of obtaining multicolor images by electrophotography, but they can generally be classified into the following types. One method is to use a single photoreceptor and repeat the formation of a latent image by image exposure and development with color toner depending on the number of separated colors, so that the colors are overlapped on the photoreceptor, or the colors are transferred to a transfer material each time the development is performed. This is a method of transferring and overlapping colors on a transfer material.
The second method uses a device having a plurality of photoconductors corresponding to the number of separated colors, simultaneously exposes each photoconductor with a light image of each color, and transfers the latent image formed on each photoconductor to color toner. In this method, the image is developed with a 100% polyurethane resin, and then transferred onto a transfer material in order to obtain a multicolor image by overlapping the colors. The first method has a major drawback in that a plurality of latent image formation and development processes must be repeated, and image recording takes time, and it is extremely difficult to speed up the process. In addition, the second method uses multiple photoreceptors in parallel, so it is advantageous in terms of high speed, but
Since a plurality of photoreceptors, optical systems, developing means, etc. are required, the apparatus becomes complicated, large-sized, and expensive, making it impractical. In addition, both methods have major drawbacks in that it is difficult to align images during multiple image formations and transfers, and it is not possible to completely prevent image color shift. It also has the disadvantage that it is difficult to adjust. In order to fundamentally solve these problems, it is sufficient to record a multicolor image on a single photoreceptor with one image exposure, but the reality is that such a system has not yet been developed. [Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and is capable of forming a multicolor image on a single photoconductor at high speed with one image exposure, and has a compact device configuration. The purpose of the present invention is to provide a multicolor image forming method in which color reproduction can be easily adjusted. [Structure of the Invention] The present invention has an insulating layer on one side of a photoconductive layer and a conductive layer on the other side, at least one of the insulating layer or the conductive layer is translucent, and a plurality of types of filters are provided. A photoreceptor for forming a multicolor image having a layer having a distribution of A method of forming a multicolor image by repeating full-surface exposure and development that generates a potential pattern, characterized in that the density of the subsequent development is adjusted by changing the light amount and/or wavelength distribution of the full-surface exposure. The present invention is a multicolor image forming method, and this configuration achieves the above object. [Example] The present invention will be described below with reference to illustrated examples. In the following explanation, full-color reproduction is performed using red (R), green (G), and blue (B) filters that substantially transmit only red, green, and blue light, respectively, as color separation filters. Although the photoreceptor and the multicolor image forming method using the same will be described, the color of the color separation filter and the color of the toner used in combination with the color separation filter in the present invention are not limited thereto. 1 to 13 are cross-sectional views schematically showing examples of the laminated structure of the photoreceptor used in the method of the present invention, and FIGS. 14 to 16 are filter layers showing examples of the distribution of color separation filters, respectively. Plan, No. 17
The figures are process diagrams for explaining the multicolor image forming method of the present invention, FIG.
20 and 22 are schematic front views showing an example of a recording apparatus that implements the method of the present invention, and FIG. 21 is a schematic side view showing an image exposure portion of the recording apparatus shown in FIG. 20. 1 to 13, 1 is a photoconductor such as sulfuric acid, selenium, amorphous silicon or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc., or zinc, aluminum, antimony, bismuth, cadmium, etc. Inorganic photoconductors such as metal oxides such as molybdenum, iodides, sulfides, and selenides, or organic photoconductors such as vinylcarbazole, anthracenephthalocyanine, trinitrofluorenone, polyvinylcarbazole, polyvinylanthracene, and polyvinylpyrene. A photoconductive layer consisting of an organic photoconductor dispersed in an insulating binder resin such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluororesin, epoxy resin, etc. 2 is an insulating layer, and 3 is a conductive layer. The insulating layer 2 shown in FIGS. 1 to 4 and 9 to 13 is transparent and has red (R), green (G), blue
Filter layer 2 consisting of the distribution of color separation filters in (B)
It has a. Of these, Figures 1, 9, and 13
The insulating layer 2 shown in the figure is entirely a filter layer 2a, and an insulating material such as a transparent resin colored by adding colorants such as red, green, and blue dyes is placed on the photoconductive layer 1. It can be formed by adhering it to a predetermined pattern by printing or other means. On the other hand, in the insulating layer 2 of FIGS. 2 to 4 and 10 to 12, some layers are the filter layer 2a.
The insulating layer 2 in FIGS. 2 and 10 is formed by providing a transparent insulating layer 2b made of transparent resin or the like on the photoconductive layer 1, and applying the above-described method of forming a filter layer thereon. The filter layer 2a is provided by a similar method or by a method of depositing a coloring agent in a predetermined pattern by means such as printing or vapor deposition, and the insulating layer 2 in FIGS. In the insulating layer 2 shown in FIGS. 4 and 12, a transparent insulating layer 2b is provided, and a filter layer 2a is provided on the photoconductive layer 1 in the same manner as described above, and a transparent insulating layer 2b is provided thereon. It is something. The transparent insulating layer 2b between the photoconductive layer 1 and the filter layer 2a in the insulating layer 2 in FIGS. 2, 3, 10, and 11 is transparent in its entirety or in part on the side of the photoconductive layer 1. It may also be an adhesive layer. That is, the insulating layer 2 may be formed into a film and bonded to the photoconductive layer 1 with a transparent adhesive. Unlike the above, the insulating layer 2 shown in FIGS. 5 to 8 does not have a filter layer, and is not limited to being light-transmitting, but may be non-light-transmitting. The conductive layer 3 in FIGS. 1 to 4 is a light-opaque conductive layer made entirely of metals such as aluminum, iron, nickel, copper, or alloys thereof, similar to those in conventional photoreceptors. On the other hand, the conductive layer 3 shown in FIGS. 5 to 13 is a transparent conductive layer, and includes aluminum, silver, lead, zinc, nickel, gold, etc. in contact with the photoconductive layer 1.
A conductive thin layer 3 capable of transmitting light, consisting of a vapor deposited layer or sputtering layer of a metal such as chromium, molybdenum, titanium, platinum, etc., or a vapor deposited layer of a metal oxide such as indium oxide, tin oxide, indium-tin oxide, etc.
c, and a filter layer 3a similar to that in the insulating layer 2 described above or a transparent layer 3b. Conductive layer 3 having such a filter layer 3a
If a conductive substance such as a conductive resin is used for the filter layer 3a or the transparent layer 3b, the conductive thin layer 3c may not be provided. In the present invention, the photoreceptor 4 having the laminated structure as described above is used in the form of a cylinder, a belt, or a plate. Note that the filter layer 2a of the insulating layer 2 and the filter layer 3a of the conductive layer 3 in the photoreceptor 4 shown in FIGS. 9 to 12 have exactly the same arrangement order as the arrangement pattern of the R, G, and B filters, and are of the same color. Although the filters correspond to each other, in the photoreceptor 4 shown in FIG. 13, the arrangement order is different and the colors correspond to each other by different color combinations. The shape and arrangement of the R, G, and B filters in the filter layers 2a and 3a are not particularly limited, but a striped arrangement as shown in FIG. 14 is preferred because pattern formation is easy; 15 and 16 in that a multicolor image is reproduced.
A mosaic arrangement as shown in the figure is preferred.
The R, G, and B filters may be arranged in any direction in the spreading direction of the photoreceptor, not only in a mosaic distribution but also in a stripe distribution. That is, for example, in the case of a rotating drum-shaped photoreceptor, the length direction of the stripes may be parallel to the axis of the photoreceptor, perpendicular to it, or spiral. However, if the individual sizes of the R, G, and B filters become too large, the resolution and color mixing properties of the image will decrease, resulting in deterioration of the image quality. Or even if it is less than that, it becomes more susceptible to the influence of other adjacent color parts and it becomes difficult to form a filter distribution pattern, so in the case of three types of filter distribution as shown in the example It is preferable that the width or size is such that the length l of one cycle of the repeating arrangement is 30 to 300 μm. Note that the combination of color separation filters is not limited to the three types of R, G, and B, and the colors and number of types can be changed, so if the number of types changes, the above length l
The preferred range of will also change. Next, the multicolor image forming method of the present invention using the above-mentioned photoreceptor 4 will be explained with reference to FIGS. 17 and 18. Note that FIG. 17 shows the photoconductive layer 1 of the photoreceptor 4.
17 shows an example in which an n-type semiconductor photoconductor such as cadmium sulfide is used, and in FIG. 17, the same reference numerals as in FIGS. 1 to 8 indicate the same functional members. FIG. 17 shows a state in which the photoreceptor 4 is uniformly charged from the insulating layer 2 side by positive corona discharge from the charger 5. In this state, positive charges are generated on the surface of the insulating layer 2, and correspondingly negative charges are induced at the interface between the photoconductive layer 1 and the insulating layer 2, and as a result,
The surface potential E of the photoreceptor 4 becomes uniform as shown in the graph. For convenience of explanation, FIG. 17 shows, as an example, changes in the charging state of the photoreceptor 4 with respect to the red component L _R of the image exposure light that is incident on the above-mentioned charged portion by the image exposure device 6. In this image exposure device 6, a discharger 61 applies an image exposure to the photoreceptor 4 while performing an alternating current discharge or a direct current discharge with a charge having the opposite sign to that of the charger 5. In this case, the photoreceptor 4 is insulated. 1 to 4 or 9, in which layer 2 has a filter layer 2a
It has a layer structure as shown in FIGS. 13 to 13. When the photoreceptor 4 has a layer structure as shown in FIGS. 5 to 8 in which the insulating layer 2 does not include a filter layer, image exposure is applied from the side of the conductive layer 3 having the filter layer 3a. become. In addition, the 9th
The photoreceptor 4 shown in FIGS.
May be given from the side. In the illustrated example, the red component L _R of the image exposure passes through the R filter portion of the insulating layer 2 and makes the portion of the photoconductive layer 1 below it conductive. The negative charge at the interface with the insulating layer 2 disappears. Also, G,
Since the B filter part does not transmit the red component L _R ,
In that portion, the negative charges of the photoconductive layer 1 remain as they are. As a result, the surface potential E of the photoreceptor 4
Both the R filter portion where the negative charge has disappeared and the remaining G and B filter portions have become uniform due to the discharge of the discharger 61. This is because the positive charges on the surface of the insulating layer 2 are distributed in accordance with the negative charges at the boundary between the photoconductive layer 1 and the insulating layer 2, and a balance is maintained. The green and blue components of image exposure give similar results. Therefore, the state of the surface of the photoreceptor 4 subjected to image exposure by the image exposure device 6 does not function as an electrostatic image. The same applies when image exposure is applied from the side of the conductive layer 3 having the filter layer 3a. The above is the first latent image forming process. FIG. 17 3 shows a photoreceptor 4 on which blue light L _B obtained by passing the light from the lamp 7 through a filter F _B is uniformly incident on the surface subjected to the above-mentioned image exposure.
It shows the change in the charging state of . In the case of the photoreceptor 4 shown in FIGS. 9 to 13, this entire surface exposure is performed as follows.
It may be performed from the side opposite to the image exposure. Blue light L _B is
The R and G filter portions are not passed through, so no changes are made to those portions, but the B filter portion is passed through and the photoconductive layer 1 in that portion is rendered conductive. This neutralizes the charges at the upper and lower interfaces of the photoconductive layer 1 in the B filter portion. As a result, in the B filter portion, a potential pattern appears on the surface of the insulating layer 2 giving a complementary color image of blue formed by the previous imagewise exposure. This is shown in the lower graph of FIG. 17. As shown in FIG. 18, the potential in this electrostatic image changes depending on the amount of light during full-surface exposure, and therefore the amount of toner adhering during development also changes. By adjusting the amount of light for full-surface exposure by appropriate means, the amount of toner adhesion in the next development step, that is, the development density is adjusted. The development density can be adjusted by changing the wavelength distribution of the entire surface exposure in the same way as adjusting the light amount. For example, with a halogen lamp used as a light source for full-face exposure, not only the amount of light but also the wavelength distribution can be changed by varying the applied voltage, and with a light source for full-face exposure that has a filter attached, changing the filter can change the light source. Wavelength distribution can be changed. Since the photosensitivity of the photoreceptor also has a wavelength distribution, if the wavelength distribution of the entire surface exposure changes, the potential of the potential pattern of the photoreceptor changes and the development density can be adjusted. FIG. 17 4 shows a state in which an electrostatic image formed by full-surface exposure to blue light L _B is developed by a developing device 8Y containing negatively charged yellow toner T _Y , which is the complementary color of blue. It shows. The yellow toner T _Y adheres only to the surface of the insulating layer 2 in the B filter portion where the potential has changed due to the whole surface exposure shown in FIG. 17, and does not adhere to the R and G filter portions where the potential has not changed. As a result, a color-separated one-color yellow toner image is formed on the surface of the photoreceptor 4. The potential pattern formed by full-surface exposure is
Although some of it is canceled out by development, it is usually not uniform. The lower graph of FIG. 17 4 illustrates this situation. FIG. 17 shows a state in which the surface potential of the photoreceptor 4 after development is made uniform by discharge by the charger 9 similar to the discharger 61 of the image exposure device 6. This step does not affect the charge distribution between the insulating layer 2 and the photoconductive layer 1 in the R and G filter portions. Note that the charger 9 can also be used as the discharger 61 of the image exposure device 6. Next, the entire surface of the photoreceptor 4 in the state shown in FIG. 17, on which the yellow toner image has been formed, is exposed to green light obtained by passing the light from the lamp 7 through a green filter. As a result, as described with reference to FIG. 17, a potential pattern appears which gives a complementary color image of green to the G filter portion. When this electrostatic image is developed by a developing device containing magenta toner, the magenta toner adheres only to the G filter portion and a magenta toner image is formed in the same manner as in FIG. Of course, in this case as well, the development density is adjusted by changing the light amount or wavelength distribution of the entire surface exposure. As a result, a two-color superimposed toner image with adjusted density balance is obtained. Furthermore, after making the surface potential of the photoreceptor 4 uniform with a charger in the same manner as in FIG. A potential pattern that provides a red complementary color image appearing in the R filter portion is developed by a developing device containing cyan toner to form a cyan toner image. Here, too, the development density is adjusted by changing the light amount or wavelength distribution of the entire surface exposure. Through the above process, there is no color shift or color turbidity.
A clear three-color toner image with excellent density balance is formed on the photoreceptor 4. The formed toner image is transferred onto recording paper or the like by conventionally known means and fixed. The above explanation is based on an example in which an n-type photosemiconductor is used for the photoconductive layer 1 of the photoreceptor 4.
Of course, it is also possible to use a type optical semiconductor. In that case, the basic process remains the same, except that the positive and negative signs of the charges in the above explanation are all reversed. In any case, if it is difficult for the charger 5 to inject charges into the photoreceptor 4,
One-shot irradiation with light may also be used. Table 1 shows the relationship between the colors of the original image and the image formation by the combination of the three-color separation method and the three primary color toners in the method of the present invention described above.

【table】

〔Effect of the invention〕

According to the present invention, the entire surface charging and image exposure, which conventionally required multiple times, can be performed in one time, thereby eliminating the occurrence of color shift, and making it possible to easily adjust color balance and density, resulting in high The excellent effects of being able to obtain high-quality images and also making it possible to reduce the size, increase the speed, and improve the reliability of multicolor electrophotographic devices are obtained.

[Brief explanation of drawings]

1 to 13 are cross-sectional views schematically showing examples of the laminated structure of the photoreceptor used in the method of the present invention, and FIGS. 14 to 16 are filter layers showing examples of the distribution of color separation filters, respectively. Plan, No. 17
The figures are process diagrams for explaining the multicolor image forming method of the present invention, FIG.
FIG. 20 and FIG. 22 are a schematic front view and a second schematic view showing an example of a recording device implementing the method of the present invention, respectively.
FIG. 1 is a schematic side view showing the image exposure portion of the recording apparatus shown in FIG. 20. DESCRIPTION OF SYMBOLS 1... Photoconductive layer, 2... Insulating layer, 2a... Filter layer, R, G, B... Color separation filter, 2b... Transparent insulating layer, 3... Conductive layer, 3a... Filter layer, 3b... Transparent layer, 3c... Conductive Thin layer, 4... Photoreceptor, 5... Charger, 6... Image exposure device, 61... Discharger, 62... Mirror, 7... Lamp, _FB , _FG , _FR ... Filter, 8Y,
8M, 8C... Developing device, 9... Charger, P... Recording paper, 10... Transfer device, 11... Separator, 12... Fixing device, 13... Static eliminator, 14... Exposure device for static elimination, 15...
cleaning equipment.

Claims (1)

[Claims] 1. A photoconductive layer having an insulating layer on one side and a conductive layer on the other side, at least one of the insulating layer or the conductive layer being transparent and having a layer consisting of a distribution of multiple types of filters. A photoreceptor for color image formation is used, and after the photoreceptor is charged and imagewise exposed, an entire surface exposure is performed to produce a potential pattern on a specific type of filter portion of the filters on the surface of the insulating layer of the photoreceptor. A method for forming a multicolor image by repeating development, characterized in that the density of the subsequent development is adjusted by changing the light amount and/or wavelength distribution of the entire surface exposure. Method.