JPS6289071A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image forming device not restricted in designing by arranging means of primary and secondary electrostatic charging, image exposure, tertiary electrostatic charging, and whole face exposure successively in oppositing to a photosensitive body having a surface insulating layer and showing two or more kinds of spectral sensitivity. CONSTITUTION:Whole face charge is given to a photosensitive body 41 by a primary electrostatic charger 4 while in rotation, and an original is exposed L by receiving corona discharge from a secondary electrostatic charger 5. Then, potential is smoothened by receiving AC or DC corona discharge from a tertiary electrostatic charger 14, and primary latent image forming is completed. Then, whose face exposure is made to blue light by a light source 6B and a blue filter FB, and developed by a sleeve Y of a yellow toner developing device 17Y. Then, electrostatic charging is made again by an electrostatic charger 15 and whole face green exposure is made by a light source 6G and a green light source filter FG, and developed by a sleeve 7M of a magenta toner developing device 17M. Then, a polychromic image is formed on the drum 41 through an electrostatic charger 16, a light source 6R, a red filter FR and developing by a sleeve 7C of a cyan toner developing device 17C, and transferred on a transfer paper 8 by a transfer electrode 9.

Description

[Detailed description of the invention]

A. Field of Industrial Application The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus suitable for forming multicolor images using electrophotography. Traditionally, in obtaining multicolor images using electrophotography,
Although many methods and devices used therefor have been proposed, they can generally be classified into the following types. Part 1
One is to repeatedly form a latent image using a photoreceptor and develop it with color toner according to the number of separated colors, and then repeat the color on the photoreceptor, or transfer it to a transfer material each time it is developed. This is a method of performing irotonne. Another method uses a device that has multiple photoreceptors corresponding to the number of separated colors, and simultaneously exposes each photoreceptor with a light image of each color, and the latent image formed on each photoreceptor is colored. It is developed with toner, sequentially transferred onto a transfer material, and the colors are superimposed to obtain a multicolor image. However, the first method described above has a major drawback in that it takes time to record an image, and it is extremely difficult to speed up the recording process, since the process of forming and developing a plurality of latent images must be repeated. In addition, the second method described above is advantageous in terms of high speed because it uses multiple photoreceptors in parallel, but it requires multiple photoreceptors, optical systems, developing means, etc., so it requires multiple devices. , large size, high price, and poor practicality. In addition, with both of the above methods, it is difficult to align images when repeating image formation and transfer multiple times.
This method has a major drawback in that it cannot completely prevent color shift in images. In order to fundamentally solve these problems, it would be possible to record a multicolor image on a single photoreceptor with a single image exposure, but a method that can effectively implement this method has not yet been developed. The reality is that there is not. In particular, no consideration has been given to the developing conditions for developing with toner of each color, and as a result, it is impossible to avoid disturbances in toner images, reductions in image density, and the like. C8 Process leading to the invention In order to fundamentally solve these problems, the present inventors first invented an apparatus that can form a multicolor image by performing one image exposure on a photoreceptor. did. The apparatus performs multicolor image formation as described below using a photoreceptor having a conductive member, a photoconductive layer, and a layer containing a plurality of different types of filters. That is, an image is formed by the interface charge density between the insulating layer and the photoconductive layer by applying imagewise exposure to the surface of the photoreceptor at the same time that the surface of the photoreceptor is charged, and by uniformly exposing the image forming surface to specific light, the photoreceptor A potential pattern is formed on the filter portion, and the potential pattern is developed by a developing device containing toner of a specific color to form a monochrome toner image. After potential smoothing, uniform exposure with light transmitted through a filter part different from the previous one and development using a developing device containing toner of a different color than the previous one are performed, thereby creating two toners on the photoreceptor. A colored toner image is formed. Thereafter, potential smoothing, uniform exposure, and development are repeated as many times as necessary. As a result, toner of different colors adheres to each filter portion of the photoreceptor, forming a multicolor image (Patent Application No. 59
-83096). According to this multicolor image forming apparatus, only one image exposure is required, so there is no risk of color shift occurring. As a result of repeated studies, the inventor of the present invention has found that the above-mentioned multicolor image forming apparatus has solved the problems of the conventional apparatus described above, but the following problems still remain. There was found. That is, in the above-mentioned apparatus, since image exposure is performed from the back side of the charger during charging, there are restrictions on the design of the apparatus. Further, since image exposure is performed simultaneously with charging, electrons or holes must be moved in a short time on the surface layer of the photoreceptor, and it is necessary to use a material that has a high movement speed in these materials for the photoconductive layer. in general,
An inorganic photoconductive layer such as CdS or 5e-Te has a high electron or hole movement speed, whereas an organic photoconductive layer has a slow moving speed. In this way, the selection of the photoconductive layer material is also subject to restrictions. On the other hand, when image exposure passes through a specific filter section,
The potential generated in the specific filter section by uniform exposure to specific light becomes approximately equal to the background potential such as the recharge potential. On the other hand, due to dark decay of the photoreceptor, potential increases occur in other filter sections. For this reason, under conditions in which the low potential portion of a specific filter is developed during development, toner also adheres to other filter portions, causing a problem of color mixing. If you change the developing bias and set the conditions so that color mixing does not occur, the result will be poor gradation,
A problem arises in that only copies with missing highlights are obtained. The present inventor has made the present invention as a result of repeated research to solve the problems still remaining in the multicolor image forming apparatus related to the above-mentioned Japanese Patent Application No. 59-83096. That is, the present invention preserves the advantages of the multicolor image forming apparatus disclosed in Japanese Patent Application No. 59-83096, while eliminating the limitations in the selection of photoconductive layer materials and the complexity of designing the image exposure device and charger. It is an object of the present invention to provide an image forming apparatus that is not subject to design constraints such as the above. It relates to an image forming apparatus in which a primary charging means, a secondary charging means, an image exposure means, a tertiary charging means, and an entire surface exposure means for specific color light are disposed in order facing each other.For example, a photoconductive layer is disposed on a conductive member. , is a photoreceptor in which an insulating layer including a plurality of filters of different colors is superimposed on the surface of the conductive layer.Furthermore, when carrying out the method of the present invention, a desirable embodiment is as follows (1) , (2) or (3). (1) In the developing step, the gap between the image carrier and the developer transport member is larger than the thickness of the developer layer formed on the developer transport member ( (2) Adopt a developing step of developing the latent image using a -component developer, and in this developing step, set the amplitude of the alternating current component of the developing bias to VAC (V) and the frequency to f (Hz). ), 0.2≦Vxc/(d-J)≦, where d (wm) is the gap between the image bearing member and the developer conveying body that conveys the developer.
1.6. (3) A developing step is adopted in which the latent image is developed using a developer consisting of a plurality of components, and in this developing step, 0.2 ≦VAc/(d − f) 1 (VAc/d) 1500 ”≦1.0. The above (11, (2), and (3) will be explained in detail later.) Hereinafter, the present invention will be implemented in a multicolor image forming photoreceptor (hereinafter simply referred to as photoreceptor) and a multicolor image forming process. An example will be explained in detail.In the following explanation, a color separation filter (a filter that passes only light in a specific wavelength range) will be used to filter red, green, and blue colors that transmit only red, green, and blue light, respectively. We will only describe the photoconductor for full color reproduction using a filter, but the color of the color separation filter and the color of the toner to be combined with it are not limited to the above. Let me explain the figure.The figure schematically shows the image formation process in a part of a photoreceptor that uses an n-type (that is, high electron mobility) photosemiconductor such as cadmium sulfide as a photoconductive layer. In addition, cross-sectional hatching of each part is omitted. In the figure, 1 and 2 are a conductive substrate and a photoconductive layer, respectively, and 3 is a three-color separation filter R and G.
, B is an insulating layer containing B. Further, the graph at the bottom of each figure shows the potential on the surface of each part of the photoreceptor. First, as shown in FIG. 1 [1], when a positive corona discharge is applied to the entire surface by the primary charger 4, a positive charge is generated on the surface of the insulating layer 3, and correspondingly, the photoconductive layer 2 and the insulating N3 A negative charge is induced at the interface. Next, as shown in FIG. 1 [2], alternating current or negative discharge is applied by the secondary charger 5 to erase the charge on the surface of the insulating layer 3, and then, as shown in FIG. 1 [3], a colored image is formed. Exposure, for example red image exposure, gives R. The red light passes through the red filter section R of the insulating layer 3, and in order to make the photoconductive layer 2 below it conductive, the charges in the photoconductive layer 2 are erased in the same filter section. On the other hand,
Since the green filter section IG and the blue filter section IB do not transmit red light, the negative charges on the photoconductive layer 2 remain as they are. Next, the first
Charging is performed by the tertiary charger 14 as shown in Figure [4],
Perform an operation to smooth the potential. Due to the tertiary charging, the red filter part R is not in an electrically balanced state like the other filter parts, and a potential pattern is generated by light irradiation, although it is small. The above corresponds to the first latent image formation, but at this stage,
Not only the portion of the red filter 8 from which charges have been erased, but also the portions fG and LB where charges remain have the same potential on the surface of the insulating layer, and therefore do not function as an electrostatic image. Figure 1 [2]
Although FIG. 1 [4] shows a case where the potential after charging is approximately zero, it may be charged to a negative value. Next, as shown in FIG. 1 [5], when the entire surface is exposed to light of the same color as the one color in the filter contained in the insulating layer 3, for example, blue light L8 obtained from the light source 6B and the blue filter FB, blue light is produced. Photoconductive layer 2 below filter 8 that transmits light
becomes conductive, and a portion of the negative charges on the photoconductive layer 2 and the charges on the conductive substrate 1 in this area are neutralized, and a potential pattern is generated only on the surface of the filter B. G, which does not transmit blue light,
No change occurs in the R portion. Then, when the charged image on filter B is developed with a developer containing negatively charged yellow toner TY, the toner adheres only to the 8 parts of the insulating layer that have a potential, and development is performed (Fig. 1 [6]). . Next, in order to eliminate the generated potential difference, charging is performed by the charger 15 as shown in FIG. 1 [7], and then as shown in FIG. 1 [8].
When the entire surface is exposed to the green light t, 6 as shown in FIG. This is shown in Figure 1.

When developing with magenta toner TM as in [9], magenta toner TM adheres only to the filter G portion. Subsequently, as shown in FIG. 1 [10], after being charged again in the same way, the entire surface is exposed to red light. Although a slight potential pattern is formed on the red filter portion R, development is performed with cyan toner. However, no cyan toner adhesion occurs. That is, the potential pattern is formed although small, and the developing bias is adjusted to prevent toner adhesion. This also applies to the developing bias in other filter sections. The potential generated in the specific filter section due to the ψ ray exposure is not approximately equal to the background section 1, such as the recharge potential, but a certain potential rise occurs. For this reason, due to the dark decay of the photosensitive layer,
Even if potential increases occur in other filter sections, no problem will occur. Conventionally, under conditions that affect the low potential portion of a specific filter during development, toner adheres to other filter portions, causing color mixing. If you change the developing bias and set the conditions so that color mixing does not occur, the problem is that only copies with poor gradation and scattered highlights are obtained. The potential is always high even in the areas where the developing bias is set to approximately that potential, and has the characteristic that there is no problem of toner adhering to the filter portion and color mixing caused by setting the developing bias to approximately that potential. When the toner image obtained in this way is transferred onto a transfer material such as copy paper and fixed, a red image created by a mixture of yellow toner and magenta toner is reproduced on the transfer material by a combination of primary and three primary color toners. will be carried out. In this table, -2 is the state of the first stage of electrostatic image formation, ○ is the completed electrostatic image, ・ is the state after development, ↓ is the top)
Indicates that the state of darkness remains intact. Sky) Darkness represents the part where the electrostatic image does not exist. Although the above explanation is based on an example using an n-type semiconductor layer, it is of course possible to use a p-type (i.e., high hole mobility) optical semiconductor layer such as selenium, and in this case, the positive and negative charges can be changed. The basic processes are all the same, just the signs of are reversed. Note that if it is difficult to inject charge during primary charging, uniform irradiation with light is also used. . As is clear from the above description, according to this embodiment, after charge injection, image exposure, and charging are applied to the multicolor image forming photoreceptor, light of the same color as one of the plurality of filters is applied to the entire surface of the photoreceptor. The steps of exposing and developing are repeated depending on the number of types of filters. That is, a fine color separation filter is placed on the photoreceptor, and charge injection (steps [1] to [2] in Fig. 1), image exposure (step [3] in Fig. 1), and charging (steps shown in Fig. 1 [3]) are carried out. After step 4), the entire surface is exposed to specific light (Fig. 1 [5], [8])
A potential pattern is formed for each color portion of the color separation filter, and development is performed using toner of the corresponding color (Fig. 1 [6],

Step [9]) and repeat this to obtain a multicolor image. Therefore, according to this process, first image exposure is applied using a photoreceptor in which multiple color separation filters are arranged in a combination of fine stripes or mosaics on a photosensitive layer that is sensitive to the entire visible light range. , a first latent image is formed on the photosensitive layer below each filter in accordance with the resolved image density, and then the photoreceptor is entirely exposed to light of a specific color (in this example, the same color as the filter). A secondary latent image is formed only on the color filter, and a potential pattern is formed in accordance with the light intensity in the process of forming the primary latent image. Then, it is developed with a color toner of a color corresponding to the color of the filter, preferably a color complementary to the color that passes through the filter, and the same operation is repeated for each separated image to create a multicolor image on the photoreceptor. A multicolor image can be recorded on the transfer material at once by forming a multicolor image. FIG. 2 is a schematic diagram of an image forming section of a color copying machine in which the above process of this embodiment is carried out. In the figure, reference numeral 41 denotes a photosensitive drum made of a photosensitive member having the configuration shown in FIG. 1, and rotates in the direction of arrow a during a copying operation. While rotating, the photoreceptor drum 41 is irradiated with light by a light source 4A as needed, and the entire surface is charged with a charging electrode (primary charger) 4 (light may be irradiated immediately before charging), and the electrode ( The document is exposed to light by receiving an alternating current or corona discharge of the opposite sign from the electrode 4 from the secondary charger (secondary charger) 5, and then receives an alternating current or direct current corona discharge from the electrode (tertiary charger) 14 to smooth the potential. The first latent image forming step is completed. Next, the light source 6B and the light source blue filter FB
The entire surface of the toner is exposed to blue light obtained in combination with yellow toner, and developed by the developing sleeve 7Y of the developing device 17Y loaded with yellow toner. Subsequently, after recharging with the charger 15, the entire surface is exposed to green light from the light source 6G and the green light source filter F4, development is performed with the developing sleeve 7M of the developer 17M loaded with magenta toner, and after recharging with the charger 16, the light source 6R1 A multicolor image is formed on the photosensitive drum through full exposure with red light from the red light source filter FR and development by the developing sleeve 7C of the developing device 17C loaded with cyan toner. The obtained multicolor toner image is transferred by a transfer electrode 9 onto copy paper 8 that is supplied by a paper feeding means (not shown). However, 21 is a pre-transfer charging electrode, 2
2 is a pre-transfer exposure lamp. The copy paper 8 carrying the transferred multicolor toner image is separated from the photoreceptor drum 41 by the separation electrode 10 and fixed by the fixing device 13.
It becomes a completed multicolor copy and is ejected outside the machine. On the other hand, the toner remaining on the surface of the photoreceptor after the transfer is removed and the photoreceptor is used again. In the above image forming process, the developer used may be either a so-called one-component developer using non-magnetic toner or magnetic toner, or a so-called two-component developer using a mixture of toner and a magnetic carrier such as iron powder. I can do it. During development, a method of directly rubbing with a magnetic brush may be used, but especially after the second development, to avoid damage to the formed toner image, developer particles on the developing sleeve should be brushed against the surface of the photoreceptor. It is essential to use a non-contact development method that does not rub the surface. This non-contact method uses a one-component or two-component developer containing a non-magnetic toner or a magnetic toner, which can be colored freely, and will be described in detail below. In repeated development using an alternating electric field as described above, it is possible to repeat development several times on a photoreceptor on which a toner image has already been formed, but if appropriate development conditions are not set, This may disturb the toner image formed on the photoconductor in the previous stage, or the toner already attached to the photoconductor may return to the developing sleeve, which is a developer conveying body, and this may cause the development of a different color from the developer in the previous stage. It penetrates into the subsequent developing device where the agent is stored in ashes,
There is a problem that color mixing occurs. From the above considerations, the image forming conditions for achieving the desired density and without image disturbance or color mixing using a -component developer or a two-component developer are as follows: -component developer or two-component developer It has become clear that this exists in processes using each of these. Essentially, this development condition is essentially operating the developer layer on the development sleeve without contacting the photoreceptor. To this end, the gap between the image carrier and the developing sleeve is maintained to be larger than the thickness of the developer layer on the developing sleeve (provided there is no potential difference between them). More desirable conditions include the step of forming a latent image on the image carrier, and the step of developing the latent image using a -component developer to form a plurality of toner images on the image carrier. In the process, the amplitude of the AC component of the developing bias is changed to VAC (
v), 0.2≦VAc/(d-, f)≦1, where the frequency is f (Hz) and the gap between the image carrier and the developer conveying body that conveys the developer is d (mu). .6 must be satisfied. Further, in the image forming method, the step of forming a latent image on an image carrier, and developing the latent image using a developer made of a plurality of components to form a plurality of toner images on the image carrier, In each development process, the amplitude of the AC component of the development bias is set to V
AC (V), the frequency is fu-iz), and the gap between the image bearing member and the developer transporting member that transports the developer is d (mu), 0.2≦V, ac/(d-f ) 1. It is preferable to satisfy <vAc/d> −tsool /f−≦1.0. As a result of research on a method of forming an image by repeating the latent image formation and development, the present inventor discovered that AC bias,
It has been found that there are regions in which it is possible to obtain high-quality images without causing image disturbance or color mixing by selecting development conditions such as frequency and frequency. In the method of superimposing toner images, it is necessary to develop at an appropriate density without disturbing the toner image previously formed on the image carrier during development. A toner image is formed, and then an electrostatic latent image is generated on the image carrier by uniform exposure with specific light for recharging.
This refers to depositing toner on the electrostatic latent image from one or more developing devices to form a toner image. As a result of our study, we found that in order to satisfy this condition, it is difficult to obtain an excellent image even if the value of the gap d (mu) between the image bearing member and the developer conveying member in the development area is determined alone, and that these parameters are mutually dependent. It has become clear that they are closely related. Therefore, using the color copying machine shown in FIG. 2, an experiment was carried out using -component magnetic toner in the developing device 17 shown in FIG. 3 while changing parameters such as the voltage and frequency of the AC component of the developing bias. As a result, the results shown in FIGS. 4 and 5 were obtained. Note that the photosensitive drum 41
A toner image is previously formed on the surface. This developing device 17
1 corresponds to the developing units 17Y, 17M, and 17C shown in FIG. The developer is conveyed in the B direction -υ and is supplied to the development area. The developer is a -component magnetic developer, consisting of 70wt% thermoplastic resin, 10wt% pigment (carbon black), 20ivt% magnetic material,
A charge control agent is kneaded and pulverized to have an average particle size of 15 μm, and a fluidizing agent such as silica is added to the coarse particles. The amount of charge is controlled by a charge control agent. As the magnetic roll 43 rotates in the direction of arrow A and the sleeve 7 rotates in the direction of arrow B, the developer is conveyed in the direction of arrow B. The thickness of the developer layer is regulated by a spike control blade 40 made of a magnetic material during transportation. A stirring screw 42 is provided in the developer reservoir 47 to sufficiently stir the developer reservoir, and when the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. As a result, toner T is replenished from the toner hopper 38. A DC power supply 45 is provided between the sleeve 7 and the photoreceptor drum 41 to apply a developing bias, and the developer is vibrated in the development area E so that the developer is applied to the photoreceptor drum 41. AC power supply 4 to ensure sufficient supply.
6 is provided in series with the DC power supply 45. R is a protective resistance. Figure 4 shows the current settings: the gap d between the photoreceptor drum 41 and the sleeve 7 is 0.7 mm, the developer layer thickness is 0.3 mm, and the DC component of the developing bias applied to the sleeve 7 is 50 V. 3 shows the relationship between the amplitude of the alternating current component and the image density of the black toner image formed on the non-exposed area (the exposed area potential is OV) on the photoreceptor drum 41. Amplitude EA of AC field strength
C is a value obtained by dividing the amplitude ■Ac of the AC voltage of the developing bias by the gap d. Curves A, B, and C shown in FIG. 4 indicate average charge amounts of magnetic toner of -5 μc/g and −3 μC/g, respectively.
, -2 μc/g. A,
For both curves B and C, the amplitude of the alternating current component of the electric field is 2.
When the voltage is 00 V/w or higher and 1.5 kV/m or lower, the image density is large, and when the voltage is 1.6 kV/m or higher, it is observed that a part of the toner image previously formed on the photoreceptor drum 41 is destroyed. Ta. Figure 5 shows the frequency of the AC component of the developing bias at 2.5k.
Hz, and shows changes in image density when alternating current electric field strength, etc. are changed under the same conditions as in the experiment shown in FIG. According to this experimental example, when the amplitude EAC of the alternating current electric field strength is 500 V/m or more and 3.8 kV/m or less, the image density is large, and when it becomes 3.2 kV/m or more (shown in the lower part of Figure 6),
A part of the toner image previously formed on the photoreceptor drum 41 was destroyed. As can be seen from the results shown in Figures 4 and 5, the image density changes to become saturated or to decrease slightly after a certain amplitude, and the value of this amplitude corresponds to curves A, B, and C.
As can be seen, this can be obtained without much dependence on the average charge amount of the toner. The reason may be as follows. In other words, it is expected that the charge amount of the -component developer is widely distributed across positive and negative directions due to mutual friction between toner particles. Therefore, although the average charge amount is a small value, in reality there is a certain proportion of toner with a large charge amount, for example, 20 μc/g or more in size, and it is thought that such toner is mainly used for development. It will be done. Even if the average charge amount is controlled by a charge control agent, the proportion occupied by these toners having a large charge amount does not change significantly, and as a result, it is considered that almost no change in the development characteristics is observed. Now, when experiments similar to those shown in FIGS. 4 and 5 were conducted while changing the conditions, the relationship between the amplitude EAC of the alternating current electric field strength and the frequency could be sorted out, and the results shown in FIG. 6 were obtained. In FIG. 6, the area marked with ■ is an area where development unevenness is likely to occur due to the low-frequency development bias, the area marked with ■ is an area where the effect of the AC component does not appear, and the area marked with ■ is a region that has already been formed. Areas where destruction of the toner image is likely to occur,
0 [F] is a region where the effect of the alternating current component appears, a sufficient development density is obtained, and the already formed toner image is not destroyed, and [F] is a particularly preferable region. This result shows that in order to develop the next (later stage) toner image at an appropriate density without destroying the toner image previously formed on the photoreceptor drum 41 (at the previous stage), the amplitude of the alternating current electric field strength must be It is shown that there is an appropriate range for that frequency, and the reason is considered to be due to the reasons described below. In a region where the image density tends to increase with respect to the amplitude EAC of the alternating current electric field strength, that is, for example, regarding the density curve A in FIG. The alternating current component of the developing bias serves to make it easier to exceed the darkness value at which the toner flies from the sleeve, and even toner with a small amount of charge adheres to the photosensitive drum 41 and is developed. Therefore, the amplitude E of the AC field strength
As AC increases, image density increases. On the other hand, the image density saturates or decreases slightly as the amplitude of the AC electric field becomes thicker (for example, for the 1-variation curve A in Figure 4, the amplitude EAC of the AC electric field strength is 1 kV).
There are several possible reasons for this. As the amplitude EAC of the alternating current electric field strength increases, the toner vibrates more strongly, and the clusters formed by toner aggregation become easier to break. Only toner with a large charge is selectively attached to the photoreceptor drum 41, and small Toner with an electric charge becomes difficult to develop. Furthermore, even if toner with a small charge adheres to the -transformed photo drum 41, its mirror image force is weak, so that it is likely to return to the sleeve 7 due to the alternating current bias. Furthermore, if the amplitude of the electric field strength of the AC component is too large, the photoreceptor drum 41
Due to the leakage of surface charge, a phenomenon in which the toner becomes difficult to develop also tends to occur. In reality, it is thought that these factors overlap to saturate or lower the image density. On the other hand, when the amplitude EAC of the alternating current electric field strength is increased, the toner image previously formed on the photoreceptor drum 41 is destroyed, as described above, and the greater the alternating current component, the greater the degree of destruction. The reason for this is thought to be that the AC component exerts a force on the toner adhering to the photoreceptor drum 41 to pull it back toward the sleeve 7 . When developing toner images by sequentially overlapping them on the photoreceptor drum 41, it is a fatal problem that the toner images that have already been formed are destroyed by the subsequent development process. Also, as can be seen by comparing the results in Figures 4 and 5, when we experimented by changing the frequency of the AC component, we found that when the frequency was high (I see, the image density tended to be lower),
This is because the toner particles cannot follow changes in the electric field, so the range in which they vibrate is narrowed, making it difficult for them to be attracted to the photoreceptor drum 41. Based on the above experimental results, the present inventor has determined that in each development step,
0.2≦V, qc/(d-, f
)≦1.6, it was concluded that subsequent development can be performed at an appropriate density without disturbing the toner image already formed on the photoreceptor drum 41. be. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, the image density should be 0.4, which is the region in which the image density tends to increase with respect to the alternating current electric field in FIGS. 4 and 5. It is more desirable to satisfy the following condition: ≦Vxc/(d−f)≦1.2. Furthermore, within this region, it is more desirable that the electric field satisfies the following: 0.6≦■^c/(d-, f)≦1.0, which corresponds to a region where the electric field is slightly lower than that at which the image density is saturated. In addition, in order to prevent uneven development due to the AC component, the frequency of the AC component is set to 200 Hz or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the AC component and the magnetic roll are In order to eliminate the effect of beat caused by the rotation of the AC component, the frequency of the AC component is set to 5.
It is further desirable to set the frequency to 00 Hz or higher. Next, an experiment was conducted using a two-component developer using the developing device 11 shown in FIG. 3 in the same manner as described above, and the results shown in FIGS. 7 and 8 were obtained. The developer is a two-component developer consisting of a magnetic carrier and a non-magnetic toner.
The carrier has an average particle size of 20 μm and a magnetization of 30 emu 7.
g, a carrier created by dispersing fine iron oxide in a resin so as to exhibit physical properties with a resistivity of 1014 Ω-Cm,
The resistivity was determined by placing the particles in a container with a cross-sectional area of 0.50 cflI, applying a tough piston, applying a load of 1 kg/Cl11 on the packed particles, and applying a voltage of 1000 V/Cl between the load and the bottom electrode. This value is obtained by reading the current value when applying a voltage that generates an electric field of cm. The toner is made by adding a small amount of charge control agent to 90 w (%) of thermoplastic resin and 10 wt % of pigment (carbon black).
The material was kneaded and pulverized to have an average particle size of 10 μm. The toner was mixed with 80 wt % of the carrier at a ratio of 20 wt % to prepare a developer. Note that the toner is negatively charged due to friction with the carrier. In FIG. 7, the gap d between the photoreceptor drum 41 and the sleeve 7 is 1.0 degrees, the developer layer thickness is 0.7N, the maximum potential of the photoreceptor is 500cm, the DC component of the developing bias is 50cm, and the AC component is 50cm. It shows the relationship between the amplitude of the AC component and the image density of the black toner image formed on the non-exposed area (the exposed area potential is OV) on the photoreceptor drum 9 when the frequency of the component is set to 1 kHz. The amplitude EAc of the AC electric field strength is the value obtained by dividing the amplitude VAC of the AC voltage of the developing bias by the gap d. Curves A, B, and C shown in FIG. 7 each have an average charge amount of -30 μc.
These are the results when using those whose charge was controlled to /g, -20μc/g, and -15μc/g. For all three curves A, B, and C, the amplitude of the alternating current component of the electric field is 200 V/U.
With the above, the effect of the AC component appears, and the voltage is 2500 V/*
It was observed that when the temperature was higher than 10, the toner image previously formed on the photoreceptor drum was partially destroyed. Figure 8 shows the frequency of the AC component of the developing bias at 2.5k.
Hz, and shows changes in image density when alternating current electric field strength EAC is changed under the same conditions as in the experiment shown in FIG. According to this embodiment, when the amplitude EAC of the alternating current electric field strength exceeds 500 V/m, the image density increases, and when it exceeds 4 KV/m (not shown), the toner image previously formed on the photoreceptor drum 41 becomes Some parts were destroyed. As can be seen from the results in Figures 7 and 8, the image density changes to become saturated or slightly decrease after a certain amplitude, but the value of this amplitude is different from curves A, B, and C. As can be seen, this can be obtained without much dependence on the average charge amount of the toner. The reason may be as follows. In other words, in a two-component developer, the toner is charged due to friction with the carrier and mutual friction between the toners, and the amount of charge on the toner is expected to be distributed over a wide range, although not as much as in the -component developer. It is thought that toner with a large amount of charge is preferentially developed. Even if the average charge amount is controlled using a charge control agent, the proportion of toner with a large charge amount does not change significantly, and as a result, although changes in development characteristics may be observed, they are not considered to be significant. . Now, when we conducted an experiment similar to that shown in Figures 7 and 8 while changing the conditions, we were able to sort out the relationship between the amplitude EAC of the alternating current electric field strength and the frequency J, and obtained the results shown in Figure 9. . In Fig. 9, the area marked with ■ is an area where uneven development is likely to occur due to low-frequency development bias, the area marked with ■ is an area where the effect of the AC component does not appear, and the area shown with ■ has already been formed. Areas where toner image destruction is likely to occur, [F] and [F], are areas where the effect of the alternating current component appears and is sufficient.
! [F] is a particularly preferable region in which a high density can be obtained and the already formed toner image is not destroyed. This result shows that in order to develop the next (later) toner image at an appropriate density without destroying the toner image formed in the previous stage on the photoreceptor drum 41, the amplitude of the alternating current electric field strength and its frequency are required. This shows that there is an appropriate area for
The reason for this is the same as in the case of the one-component developer described above. That is, in a region where the image density tends to increase with respect to the amplitude EAC of the AC electric field strength, for example, in the density curve of FIG. 7, the amplitude EAC of the AC electric field strength is 0.2 to 1.2 KV/
For the dragon region, the AC component of the developing bias is
It functions to make it easier to exceed the darkness value at which the toner flies from the sleeve, and even toner with a small amount of charge is attached to the photoreceptor drum 41 and used for development. Therefore, as the amplitude of the AC field strength increases, the image density increases. On the other hand, in the region where the image density is saturated with respect to the amplitude EAC of the alternating current electric field strength, the amplitude Es of the alternating current electric field intensity Es
In the region where c is 1.2 KV/mm or more, this phenomenon can be explained as follows. That is, in this region, as the amplitude of the alternating current electric field strength increases, the toner vibrates strongly, and the clusters formed by collecting the toner in the tube become easily broken, so that only toner with a large charge selectively moves to the photoreceptor drum 41. Toner particles with a small charge attached to the surface are difficult to develop. Further, even if toner with a small charge adheres to the -transformation photo drum 41, its mirror image force is weak, so that it is likely to return to the sleeve 7 due to the alternating current bias. Furthermore, if the amplitude of the electric field strength of the alternating current component is too large, the charge on the surface of the photoreceptor drum 41 leaks, making it difficult to develop the toner. In reality, it is considered that these factors overlap and the image density remains constant despite the increase in the AC component. Furthermore, by increasing the alternating current electric field strength, for example, curve A in FIG.
Under the conditions obtained, if the amplitude is set to 2.5KV/f1 or more,
As mentioned above, it has been found that the toner image previously formed on the photoreceptor drum 41 is destroyed, and the larger the alternating current component, the greater the degree of destruction. The reason for this is thought to be that the AC component exerts a force on the toner adhering to the photoreceptor drum 41 to pull it back toward the sleeve 7 . When developing toner images by sequentially overlapping them on the photoreceptor drum 41, it is a fatal problem that the already formed toner images are destroyed during the subsequent development. Also, as can be seen by comparing the results in Figures 7 and 8, when we experimented by changing the frequency of the AC component, the higher the frequency, the lower the image density.This is because the toner particles This is because the vibration range is narrowed because it cannot follow changes in the electric field, making it difficult to adhere to the photoreceptor drum 41. Based on the above experimental results, the present inventor has determined that in each development step,
When the amplitude of the AC component of the developing bias is VAC (V), the frequency is f (H2), and the gap between the photosensitive drum 41 and the sleeve 7 is d (m), 0.2 ≦VAc/(d
-J) f(VAc/d) If development is performed under conditions satisfying -15001/j≦1.0, subsequent development can be performed at an appropriate density without disturbing the toner image already formed on the photoreceptor drum 41. The conclusion was that it could be done. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, among the above conditions, 0.5≦VAc/(d-f) lVAc/d) -15001/f≦1 It is more preferable to satisfy .0. Furthermore, if 0.5≦VAc/(d・su) 1(VA c/a)-15001/su≦0.8 is satisfied, a clearer multicolor image with no color turbidity can be obtained, and a multicolor image can be obtained many times. Even if the toner is operated, it is possible to prevent toner of a different color from entering the developing device. In addition, in order to prevent uneven development due to the AC component, the frequency of the AC component is set at 200
Hz or higher, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the frequency of the AC component is set to 500 Hz or higher in order to eliminate the influence of the beat caused by the AC component and the rotation of the magnetic roll. It is even more desirable to do so. . The image forming process according to the present invention is as exemplified above, and subsequent toner images are sequentially developed on the photoreceptor drum 41 at a constant density without destroying the toner image formed on the photoreceptor drum 41. To achieve this, as development is repeated, (1) Use toners with a larger charge amount. ■ Gradually reduce the amplitude of the electric field strength of the AC component of the developing bias. ■ Gradually increase the frequency of the AC component of the developing bias. It is more preferable to employ these methods individually or in any combination. That is, toner particles with a larger amount of charge are more easily affected by the electric field. Therefore, if highly charged toner particles adhere to the photoreceptor drum 41 during initial development, these toner particles may return to the sleeve during subsequent development. Therefore, the above-mentioned point (2) is to prevent the toner particles from returning to the sleeve during the subsequent development by using toner particles with a small amount of charge in the initial development. Method (2) is a method in which the toner particles already attached to the photoreceptor drum 41 are prevented from returning by decreasing the electric field strength sequentially as development is repeated (that is, as development progresses to later stages). Specific methods for reducing the electric field strength include a method in which the voltage of the alternating current component is gradually lowered, and a method in which the gap d between the photoreceptor drum 41 and the sleeve 7 is made wider as the developing stage progresses. In addition, the above-mentioned method (2) is a method in which the frequency of the alternating current component is gradually increased as development is repeated, thereby preventing the toner particles already attached to the photoreceptor drum 41 from returning. These ■
■■ is effective when used alone, but it is even more effective when used in combination, for example, by increasing the toner charge amount (and gradually decreasing the AC bias) as development is repeated. , When adopting the above three methods, appropriate image density or color balance can be maintained by adjusting the DC bias respectively. Figure 10 is a schematic cross-section of a photoreceptor that can be used in the present invention. A photoconductive layer 2 is provided on a conductive member or substrate 1, and a required color separation filter such as red (R
), green (G), and blue (B) filters.
fi3 is stacked. The conductive substrate 1 may be made of metals such as aluminum, iron, nickel, copper, or alloys thereof, and may have an appropriate shape and structure as necessary, such as a cylindrical shape or an endless belt shape. The photoconductive layer 2 is made of sulfur, selenium, amorphous silicon or Ti.
Photoconductors such as alloys containing t, selenium, tellurium, arsenic, antimony, etc.; or inorganic photoconductors of metal oxides, iodides, sulfides, and selenides such as zinc, aluminum, antimony, bismuth, cadmium, molybdenum, etc. Conductive substances: Organic photoconductive substances such as vinyl carbazole, anthracenephthalocyanine, trinitrofluorenone, polyvinyl carbazole, polyvinylanthracene, and polyvinylpyrene are combined with polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, and acrylic. resin, silicone resin,
It can be composed of a material dispersed in an insulating binder resin such as a fluororesin or an epoxy resin, or a functionally separated organic photoreceptor consisting of a charge generation layer and a charge transport layer. The insulating layer 3 is made of a transparent insulating material, such as various polymers,
It can be made of resin or the like, and has a colored portion on its surface or inside that acts as a color separation filter. As shown in FIG. 10 fa), the colored portion is formed by attaching an insulating material colored by adding a coloring agent such as a dye having a desired color onto the photoconductive layer 2 in a predetermined pattern by printing or other means. , or as in FIG. 10 (bl), the colorant is added to the photoconductive layer 2
It can be formed by adhering it in a predetermined pattern on a colorless insulating layer 3a that has been uniformly formed thereon by means such as printing or vapor deposition. Furthermore, even if a film-like insulating material on which a colored portion is formed in advance is attached on the photoconductive layer, it is possible to
It is possible to construct a photoreceptor having the structure shown in FIG. Although the shape and arrangement of the plurality of types of fine color separation filters constituted by the colored portions are not particularly limited,
In the case of a linear shape as shown in FIG. 11(a), for example, when the photoreceptor is drum-shaped, the lines may be perpendicular to the rotation direction, parallel to the direction of rotation,
Both can be used. Alternatively, the size of each filter is preferably 30 to 500 μm during color repetition (as shown in FIG. 11). If the size is too small, it will be susceptible to the influence of adjacent parts of other colors, and if the width of the filter is equal to or smaller than the particle size of the toner particles, it will be difficult to create. In addition, if the size of the filter becomes too large, the resolution and color mixing properties of the image will decrease, and the image quality will tend to deteriorate. It is preferable that each filter has a high resistance. If the filter has a low resistance, a gap should be provided. They are electrically insulated from each other by interposing an insulating material. Figure 12 shows the spectral sensitivity of the 5e-Te-based photoconductive layer, and its wavelength range changes depending on the Te content. , 20 when using a 5e-Te based photoconductive layer.
% of Te is preferable. % in the figure represents the Te content (% by weight). Furthermore, some organic photoconductive materials (OPC) do not have spectral sensitivity to infrared light. Their spectral sensitivity characteristics are illustrated in FIG. As shown in Figure 14, the charge generation layer (CGL) 2
A two-layer structure consisting of a and a charge transport layer (CTL) 2b is preferable, but a single layer formed by mixing the two can also be used. In the case of a two-layer structure, it is preferable that the CGL is composed of a charge generating substance as the CGL and a CTL material as a binder. The materials constituting the photoconductive layer shown in FIG. 13 are shown in Table 2 below. All have almost no or low spectral sensitivity to infrared light. (1) is hardly sensitive to ultraviolet light. When using a photoconductive layer that has substantial spectral sensitivity to infrared or ultraviolet light, color separation filters B, G, and R should all be used for wavelengths of 400 nm or less (ultraviolet light component) or 700 nm or more (red light component). It is designed so that it does not have a spectral transmittance for external light (external light component), or it is designed so that it does not have an ultraviolet light or infrared light component for imagewise exposure. In the multicolor image forming apparatus shown in FIG. 15, a toner image of one color is formed by one rotation of the photoreceptor 41, and filters FB, F4 . This image forming apparatus differs from the image forming apparatus shown in FIG. 2 in that the entire surface is exposed by a lamp 6 equipped with a lamp F, and a charger 5 or 14 is used to make the surface potential of the photoreceptor 41 uniform after development. Similar to the multicolor image forming apparatus shown in FIG. 2, this multicolor image forming apparatus also performs the same image forming operation as described for FIG. A monochromatic image can be formed. That is, for example, when forming a three-color image, the photoreceptor 41 is charged by the primary charger 4, the surface potential is made uniform by the secondary charger 5, image exposure 4 is performed, and the tertiary charger 14 discharges the photoreceptor 41. Next, on the surface of the photoreceptor 4,
The entire surface is exposed with the light from the lamp 7 transmitted through the blue filter FB, and the potential pattern formed thereby is developed by the developing device 8Y to form a yellow toner image. This toner image is stored in a developer ff18M, an 8C1 pre-transfer charger 21,
The transfer device 9, the separator 10, the cleaning device 16 and the electric current generator 44 pass through without being affected. For example, when the photoreceptor 41 on which the toner image has been formed reaches the position of the tertiary charger 14, it receives a corona discharge and its surface potential becomes uniform, and the entire surface of the photoreceptor 41 is exposed to light obtained from the lamp 7 and the red filter FR. A potential pattern is formed. Subsequently, this is developed by the developing device 8C to form a cyan toner image. Similarly, a potential pattern is formed by the lamp 7 and the green filter F4, and development is performed by the developing device 8M, thereby obtaining a three-color toner image. The order in which the overall exposure and development devices are used is not limited to the above. This multicolor image forming apparatus has a simple configuration that is almost the same as a monochrome copying machine except for the increased number of developing devices.
It has the advantage of being able to achieve smaller size and lower cost. The same reference numerals as in FIG. 2 in FIG. 15 indicate the same functional members. Next, a specific example carried out with the configuration described above will be described using the apparatus shown in FIGS. 2 and 3. 1. A recording device shown in FIG. 2 was used. However, the photoreceptor 41 is a long-wavelength sensitized 5e-
A photoreceptor 41 having a thickness of 20 μm and having the structure shown in FIG. 10 (al) and FIG. The surface potential of the photoreceptor 41 was charged to -2000 V. Next, a secondary charger 5 consisting of a scorotron corona discharger having an AC component raised the surface potential of the photoreceptor 41 to +too much.
It was charged so that it became v. Next, image exposure was performed. J.I.
1. A halogen lamp was used during exposure, and infrared and ultraviolet light was filtered out in advance. Next, it was charged with a scorotron discharger (tertiary charger) 14 so that the surface potential became about +100V. Next, by performing uniform exposure through a blue filter, an electrostatic image having −300V was formed with respect to the background portion OV. The potential contrast generated at this time was about 1/3 of that in the case of using a transparent insulating layer because each filter had three divided potential contrasts. This electrostatic image was developed using a developing device 17Y as shown in FIG. In developing device 17Y, magnetite is contained in the resin at 50 wt%.
Contains dispersed particles, average particle size is 30μm, magnetization is 30emu
/g, with a carrier having a resistivity of 100 or more; an average particle size of 10 parts by weight of a benzidine derivative as a yellow pigment and other charge control agents added to a styrene-acrylic resin.
A developer consisting of a positively charged non-magnetic toner of 0 μm was used under conditions such that the ratio of toner to developer was 20 wt %. Further, the outer diameter of the developing sleeve 7 is 30 mm, the rotation speed is 100 rpm, the magnet body 43ON, the magnetic flux density of the S magnetic pole is 900 Gauss, the rotation speed is 11000 rpm, and the thickness of the developer layer in the developing area is 0.7 The gap between the developing sleeve 7 and the photoreceptor 41 is 1.0, and the amplitude is 2000
A non-contact development condition was applied in which a voltage of V) was applied. Note that while the electrostatic image is being developed with the developer +7Y, it is not being developed like the other one shown in Figure 2. 517M and 17C were kept undeveloped. In that case, it is necessary to disconnect the developing sleeve from the power source 45, 46 and set it in a floating state, or to ground it, or to actively supply the developing sleeve with a direct current of the same polarity as the electrostatic image (i.e., toner charging and 'f! polarity). This is achieved by applying a bias voltage, and it is particularly preferable to apply a DC bias voltage. In addition, the driving of the developing device was stopped during non-developing time. Since the developing devices 17M and 17C are also designed to perform development under the same non-contact developing conditions as the developing device 17Y, the developer layer on the developing sleeve does not need to be removed. This developing device 17M uses a developer in which the toner of the developing device +7Y is changed to a toner containing polytungstophosphoric acid as a magenta pigment instead of a yellow pigment, and the developing device 17C also uses toner. A developer was used in which the cyan pigment was changed to a toner containing a copper phthalocyanine derivative. Of course, color toners based on other pigments or dyes can be used, and the order of developing colors can be appropriately determined so as to obtain clear color images. In particular, the order of developing colors may be related to the sharpness of the color image and the potential contrast that can be obtained, and therefore needs to be carefully determined. The surface of the photoreceptor 41 developed by the developer 17Y was charged with a scorotron corona charger, and the surface potential of the electrostatic image was -300V with respect to the background area -○■. This electrostatic image
DC component -50V, AC component 2.5K to the developing sleeve
Hz and a voltage of 2000 V/7X circuit v was applied, but development was carried out in the developing device 17M under the same conditions as in the developing device +7Y. Similarly, a scorotron charger forms an electrostatic image with a surface potential of 1250 kHz, and this electrostatic image is transferred to a developing sleeve at a DC component of -50 V and an AC component of 2.5 kHz.
, 2,000 V was applied, but under the same conditions as in the developing device 17Y, development was performed using the developing device 17C. When this third development is performed and a three-color image is formed on the photoreceptor 41, the corona discharger 21 and the pre-transfer lamp 22 are activated, thereby transferring the color image. The image was easily transferred onto copy paper 8 using a transfer device 9, separated using a separator 10, and fixed using a heat roller fixer 13. The photoreceptor 41 to which the color image has been transferred is subjected to static electricity removal by the static eliminator 11 while being irradiated with white light.
The residual toner is removed from the surface by the cleaning blade of , and when the surface on which the color image has been formed passes through the cleaning device 12, one cycle of color image recording is completely completed. The color image recorded in the above manner was extremely clear, with no color mixing not only in areas where the color toners were loosely adhered to each other, but also in areas where they were closely adhered. Disaster Plate 1 CGL shown in Table 2 (11) and Figure 13 (ii). A charge injection layer is provided on the A1 substrate using a CTL material, and a 25 μm thick CTL layer is placed on top of the charge injection layer using polyester as a binder.
A photoreceptor having the structure shown in FIG. 14 was constructed by providing a photoreceptor layer having a thickness of 1 μm and a CGL layer, and further providing a mosaic filter having a thickness of 20 μm as in Example 1. 5e-T
In order to compensate for the lack of blue sensitivity compared to the e-photoreceptor, a blue fluorescent lamp is used in addition to a halogen lamp as the image exposure light source, and the circumferential speed of the photoreceptor is set to 50 mm/sec because of the low photosensitivity. Image formation was performed under the following conditions. Although the obtained potential contrast was about 2/3 lower than that of Example 1, a good color image was formed under the same developing conditions. In addition to the above-mentioned developing method, as a modification of the developing method that is performed without sliding contact with the photoreceptor, only the toner is taken out from the composite developer onto the developer transport carrier, and the toner is developed in an alternating electric field. Method of one-component development (Japanese Patent Application Laid-open No. 59
-42565, Japanese Patent Application No. 58-231434), a method in which linear or mesh control electrodes are provided and development is carried out using a one-component developer in an alternating electric field (Japanese Patent Laid-Open No. 56-125753).
No.), a method in which a similar control electrode is provided and development is carried out using a two-component developer in an alternating electric field (Japanese Patent Application No. 58-97973).
Needless to say, method No. 1) is also included in the multicolor image forming method according to the present invention. In the above embodiments, corona transfer is used as the toner image transfer method, but other methods may also be used. For example, Japanese Patent Publication No. 46-41679, No. 48-
When the adhesive transfer method described in Japanese Patent No. 22763 is used, transfer can be performed without considering the polarity of the toner. In addition, the layer structure of the photoreceptor can be made transparent by providing a transparent insulating layer, a photoreceptor layer, a conductive layer, and a filter to provide primary and secondary charging from the transparent insulating layer side, image exposure from the filter side, and overall exposure. A configuration may also be adopted in which development is performed from the insulating layer side. In addition, all of the above explanations have been made regarding examples of color copying machines that use so-called three-color separation filters and three primary color toners, but embodiments of the present invention are not limited to this, and various types of multicolor image recording Can be widely used in devices, color photo printers, etc. It goes without saying that the combination of the color of the separation filter and the color of the toner corresponding thereto can be arbitrarily selected depending on the purpose. For example, a process for obtaining two-color copies can be considered, but in this case, B (G
) It is possible to use a document in which filters are scattered and distributed, and a document consisting of two colors, a red part and a topping part, can be used. In this case, if you use basically the same process as above (however, the entire surface is exposed with G and R or G and B), the copy will be made from black toner and red toner for the main parts of the original. There is a process in which a black copy area that is almost black is obtained, and a red area made of red toner is obtained for the red area of the original. Therefore, the term "multiple types of filters" in this specification refers to a photoreceptor that has a layer consisting of a part of the car model that does not have a color filter (which may be transparent resin or air, etc.). Since the part without this filter can be regarded as a transparent filter, such cases are also included. Note that the term "electrification" as used herein includes cases where the surface potential becomes 0 or the surface charge disappears when "charging" is performed. In addition, in the above explanation, the spectral characteristics of the specific light for full-surface exposure are those of the same color as the filters of the photoreceptor, green (G), blue (B), and red (R), but the spectral characteristics is not limited to G, B, and R. In short, any spectral characteristic is sufficient as long as it forms a potential pattern only on a specific filter section (not necessarily constant) corresponding to specific light on the photoreceptor by full-surface exposure to specific light.For example, if a potential pattern is formed on a blue filter For example, when a pattern is formed, the entire surface is exposed using a material having broad spectral characteristics including wavelengths of approximately 500 nm or less and 400 nm or less. Furthermore, the present invention can be similarly applied to photoreceptors in which the photosensitive layer has a color separation function as described in Japanese Patent Application No. 59-199547 and Japanese Patent Application No. 59-201085. G. Effects of the Invention As explained above, based on the present invention (the image forming apparatus has two
The structure has a structure in which a parasitic charging means, a secondary charging means, an image exposure means, a tertiary charging means, and an entire surface exposure means for specific color light are sequentially arranged in opposition to a photoreceptor exhibiting a spectral sensitivity of spectral sensitivity or higher. The resulting images are free from defects such as color shifts and have high image reproduction fidelity. Furthermore, since the image exposure means and the charging means can be provided separately, there is no restriction on the photoconductive layer material, such as having to use a photoconductive layer material with a high hole or electron movement speed. There is a high degree of freedom of choice. Further, the design of the image exposure means and the charging means is freed from complexity.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention; FIG. 1 is a process flow diagram for explaining the image forming process; FIGS. 2 and 15 are a schematic front view of the inside of the image forming apparatus; Figure 3 is a cross-sectional view of the developing device, Figures 4 and 5 are graphs of data obtained when using a single-component developer, and Figure 6 is the amplitude of AC bias when using a single-component developer. Figures 7 and 8 are graphs of data obtained when using a two-component developer. Figure 9 is the amplitude of AC bias when using a two-component developer. Graph showing the relationship between and frequency, Figure 10 (al, (
bl, (C), (di and FIG. 14 are cross-sectional views of each photoreceptor, FIG. 11(a), FC) are plan views showing the arrangement of filters on the surface of the photoreceptor, and FIGS. FIG. 13 is a graph showing the spectral sensitivity characteristics of the photoconductive layer. In addition, in the symbols shown in the drawings, 1... Conductive substrate 2... Photoconductive layer 3... Contains a color separation filter. Insulating layer 4・
・・・・・・・・・− Human charger 5・・・・・・Secondary charger 6.6B, 6G, 6R・・・Exposure lamp 7
．． 7Y, 7M, 7C......Current (elephant sleeve 8...Copy paper 14...Tertiary charger 15.16... ...Recharger 17.17Y,
17M, 17C...Developer 41...
...Photoreceptor drum R...Red filter G...Green filter B...Blue filter Fa... ...Blue filter F, ......Green filter F, ......Red filter LR...Red light L8... ...Blue light L9...Green light TV...Yellow toner TM...
. . . Magenta toner D . . . Developer T . . . Toner.

Claims (1)

[Claims] 1. A primary charging means, a secondary charging means, an image exposure means, a tertiary charging means, and an entire surface exposure means for specific color light are arranged opposite to a photoreceptor having a surface insulating layer and exhibiting two or more types of spectral sensitivities. Image forming devices arranged in sequence.