JPS62196673A - Four-color electrophotographic copying method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Technical field〕 The present invention relates to a four-color electronic copying method.

(Prior Art) As a so-called color electronic copying method for copying color images, the Carlnon method is well known. However, this type of color electronic copying method essentially expresses a color image by superimposing a magenta visible image, a cyan visible image, and a yellow visible image, so when transferring each color visible image, Extremely high precision alignment of the visible images with each other is required.

Further, in the color copy gap, black is expressed by a mixture iC of six types of toner, so it is a cloudy black that is different from pure black.

On the other hand, in office documents that show most of the copied manuscript, even if it is called a color manuscript, only two to six colors are used in addition to black, and it is not necessarily full color. No need to copy. In addition, @office documents are mainly text information, which is essentially a line image, so in the Carlnon color copying method, color shifts are noticeable when the visible images of each color are superimposed. Cheap. Furthermore, most text information is black, but this is not expressed as pure black.

(Purpose) The present invention has been made in view of the above-mentioned circumstances, and its object is to be able to express each color image with a single type of toner, so that each color image can be expressed without color fading. To provide a new four-color electronic copying method capable of clearly reproducing images in pure colors.

(composition〕 The present invention will be explained below.

In the four-color electronic copying method of the present invention, a composite photoreceptor is used. The composite photoreceptor has 3-1 and a second photoconductive layer. The photoconductive layer of No. 1.1 has high photosensitivity to red light, no photosensitivity to blue light, and the photosensitivity gradually decreases from wavelength 600 nm to 500 nm Vc.

In FIG. 2, song @2-1 shows an example of such spectral sensitivity.

The second photoconductive layer has a photosensitivity to W color light, no photosensitivity to red light, and has a wavelength range of 500 nm to 600 nm.
Photosensitivity gradually decreases over nmVc.

In Figure 2, curve 2-3 shows an example of such spectral sensitivity.

In this way, the spectral sensitivities of the fang 1 and the second photoconductive layer are reversed in magnitude in the wavelength range of 500 to 600 nm. However, when referring to the spectral sensitivity of the first and second photoconductive layers, it should be noted that this spectral sensitivity does not mean the spectral sensitivity of the photoconductive layer alone, but the spectral sensitivity of the composite photoreceptor. Yes, since the first and second photoconductive layers are stacked on each other, the photoconductive layer located at the lower end is irradiated with light through the upper photoconductive layer, so that the lower photoconductive layer is exposed to light. The spectral sensitivity is limited by the spectral transmittance of the overlying photoconductive layer. For example, in Figure 2, if the lower photoconductive layer has a spectral window as shown in curve 2-2, but the upper photoconductive layer has a spectral transmittance as shown in curve 2-6, then The spectral sensitivity of the lower photoconductive layer within the photoreceptor is the spectral sensitivity of curve 2-6. photoconductive 4V
The spectral sensitivity related to C refers to the spectral sensitivity of such a composite photoreceptor.

Now, the four-color electronic copying method of the present invention uses a blue process,
It has a red process, an A color process, and a black process.

The blue process includes a reverse charging process, an image M light process, a developing process, and a transfer process.

The reverse charging step is a step in which the photoconductive layers 3.1 and 2 of the composite photoreceptor are charged in opposite directions to each other, and the surface potential of the photoreceptor becomes zero. This reverse charging process will be described in detail later, but the reverse charging process is performed in both the red process and the A color process, as will be described later.

The image exposure step is a step of irradiating the original light image onto the photoreceptor after one reverse charge, but in the blue process, this original irradiation is performed through a filter that transmits light with a wavelength of 550 nm or less. It is done. The spectral transmittance of this filter is, for example, as shown by curve 4-1 in Figure 4.

In the developing step, the electrostatic layer formed on the composite photoreceptor in the image exposure step is developed with blue toner.

The visible image formed by this blue toner is then transferred onto transfer paper in a transfer process.

The red process includes a reverse charging process, an image 1 exposure process, a developing process, and a transfer process. The reverse charging process is identical to that in the blue process.

In addition, the image exposure step in the red process is 550 n
This is carried out by irradiating an optical image of the original through a filter that transmits light with a wavelength of m or more. The spectral transmittance of this filter is, for example, as shown in the song @4-2 in Figure 4.

Also, in the red process, development is done with red toner,
Visible 1 damage caused by red toner is transferred onto transfer paper in the transfer process. .

Next, regarding the A color process, this A color process also includes a reverse charging process, an image exposure process, a developing process, and a transfer process.

Even in the A color process, the reverse charging process is the blue process,
It is the same as that in the red process.

In the image exposure process, a filter that transmits light with a wavelength of 500 to 550 nm or a filter with a wavelength of 550 to 600 nm is used.
The optical image of the document is irradiated onto the composite photoreceptor through a filter that transmits light with a wavelength of nm.

A color toner is used in the development process, and A color toner is used in the transfer process.
A visible image of colored toner is transferred onto the transfer paper.

In the A color process, during the image exposure process, 500 to 550
If you use a filter that transmits light with a wavelength of nm, the green and cyan colors on the document will be different. : Can be reproduced in A color.

Furthermore, when a filter that transmits light with a wavelength of 550 to 600 nm is used, green, yellow, and 'rA colors on the original can be displayed.

Second, to explain the black process, the black process includes a charging process, an image exposure process, a developing process, and a transfer process.

The charging step is a step of charging only one of the first and second photoconductive layers in the composite photoreceptor, and in the image exposure step, the composite photoreceptor is irradiated with a document light image.

The formed blank image is then developed with black toner (development step), and the resulting black visible image is transferred onto transfer paper (transfer step).

Now, in the blue process, red process, A color process, and black process, the visible images of each color are transferred onto the same transfer paper, but during each transfer, the visible images of each color are aligned with each other. .

Note that the blue process, red process, A color process, and black process may be performed in any order.

This will be explained below with reference to the drawings. In order to give a more concrete explanation, it is assumed that the filter used in the image exposure step in the A-color process is one that transmits light with a wavelength of 500 to 550 nm, and is green, which is the color of the A-color toner. Therefore, hereinafter, the A color process will be referred to as the green process.

Further, it is assumed that there are images of four colors, black, red, spine, and green, on the color original, and that the background of the color original is white.

The filter used in the blue process has a spectral transmittance as shown in curve 4-1 in Figure 4, and the filter used in the red process has a spectral transmittance as shown in curve @4-2 in Figure 4. The filter used in the green process is
It is assumed that the spectral transmittance is as shown in the song @4-3 in the figure.

Now, in the case of a color document having a four-color image as described above, each color image portion of the document generally has a spectral reflectance as shown in FIG. That is, 1. In the tFS diagram, curves 6-1.6-2.6-3.6-4.6-5 represent the spectral reflectance in the white background area, blue image area, red image area, green image area, and black image area, respectively. show.

Now, in FIG. 1, the reference numeral 1u indicates a composite photoreceptor. The composite photoreceptor 10 includes two photoconductive layers 10A and 10B stacked on a conductive substrate 10C.

The photoconductive layer 10A has a spectral sensitivity as shown by curve 2-1 in FIG. In addition, the light guide layer 10
B has a spectral sensitivity as shown in curve 2-6 in FIG. This corresponds to what has been referred to as the second photoconductive layer in the explanation so far. However, the spectral sensitivity 2-6 (Fig. 2) in the photoconductive layer 10B is determined not by the spectral sensitivity of the photoconductive layer 2B alone, but by the spectral sensitivity of the composite photoreceptor 10Vc, that is, the spectral transmittance of the photoconductive layer 10A. It is regulated.

In Figure 1.1, the photoconductive layer of ].1 is the upper layer, but it should be noted that the photoconductive layer of 1.1 may also be the lower layer.

In Figure 1, the flow of arrows (I), (1), (1v)
indicates a black process, (1), (1), (V) indicates a red process, and (1), CI), (■) and (1)
, (1), and (■) indicate the blue process and green process, respectively.

Therefore, the black process, red process, blue process, and green process 110 will be explained below based on FIG.

Looking at the black process, Figure 1 (1) and (l
[) indicates the charging process, and Figure 3.1 (IV) shows 1i! 1
ilIIμ light step and development step are shown.

First, I will explain the charging process, which can be easily understood if you consider the spectral sensitivity of each photoconductive layer.
When the photoconductive layer 10A is irradiated with red light, only the photoconductive layer 10A becomes a conductor. Therefore, if the composite photoreceptor 10 is charged with positive polarity while being uniformly irradiated with red light, the result will be 1.1.
As shown in FIG. (1)K, the photoconductive layer 10B? electricity through 2
A state in which multiple layers are formed is realized. This state is referred to as the photovoltaic layer 10B being charged, with the photovoltaic layer 10B being viewed as a capacitor. The above-mentioned charging is referred to as primary charging.

When the photoconductive layer 10B is charged as shown in FIG.
It is induced at the interface between 0C and the photoconductive layer 10B.

Next, when primary charging and reverse secondary charging are performed in the dark, the photoconductive layer 10A acts as an electrical insulator, so the negative charge due to secondary charging is
The surface of the photoconductive layer 10A is charged. At this time, if the absolute value of the charge amount of the primary band 'torque' and the secondary phase 'torch is made equal, then 1
Positive charges due to secondary charging and negative charges due to secondary band '#IL form a pair 7, as shown in FIG. 1 (1), 5VC1 photoconductive layer 1
A state in which only 0A is charged is realized. At this time, the surface potential of the composite photoreceptor 10 is negative and developable.

Now, in this state that only the photoconductive layer 10A is charged, a light image of the original O is irradiated (image exposure step).

The effect 7 of this image exposure will be considered for each color image of the original O. Refer to (IV) in FIG.

First, if we look at the area corresponding to the white background of the document, we can see that the photoreceptor 1
This part of 0 is illuminated with white light. Since white light includes the entire spectrum, the charged state of the photoconductive layer 10A is released at this location, and the surface potential of the photoreceptor becomes O at this location. Furthermore, since the photoconductive layer 10A has high photosensitivity to red light Q, the charging state is resolved and the surface potential is reduced even at the photoreceptor portion corresponding to the red image area of the original (which is irradiated with red light). It becomes 0.

Next, the part of the photoreceptor corresponding to the green image of the original is illuminated with green light, and the spectrum of this green light is
7C500-600 nm as shown in curve 6-4 in Figure 6
Therefore, the photoconductive layer 10
It is made of AY conductor. Therefore, the charged state of the photoconductive layer 10A is eliminated at this portion as well, and the surface potential becomes O. Finally, consider the portion of the photoreceptor that corresponds to the blue image area of the original. Photoconductive j! 10A does not inherently have photosensitivity to back-colored light. However, the light from the blue image area of the original O is transmitted to the photoconductive layer 1, as shown in track @6-2 in Figure 5.
The long wavelength region having photosensitivity of 0A also has a tail, and therefore, due to this long wavelength component, the photoconductive layer 10A7
If it can be made into a conductor and exposed with a sufficient amount of light, the charged state of the photoconductive layer 10A can be canceled even at this part, and the photoreceptor surface potential can be reduced to 0, or at least the potential after secondary charging can be reduced. The surface potential can be set to be sufficiently low compared to the above.

Since most of the photoreceptor portion corresponding to the black image of document 0 is not irradiated with light, the surface potential after the secondary charging is substantially preserved in this portion.

Therefore, picture 11 as shown above! After the exposure process, a black visible gland corresponding only to the black drawing method of original 0 is obtained by exposure with positively charged black toner TICK. Then, the black color process is completed by transferring this onto a transfer paper (not shown in FIG. 1).

Next, the red process will be explained.

After positive primary charging (Fig. 1 (I)), negative secondary charging is performed, and if the absolute value of the secondary charging is smaller than that of the primary charging, it becomes 1,4'- Figure 1 (I
As shown in I), the photoconductive layer 10A.

A state in which an electric double layer is formed is realized through each of the electrodes 10B. Therefore, in this state, the photoconductive layer 10A
, If 10B is likened to a capacitor, both photoconductive layers 10A and 10B are in a charged state,
Since the directions of the dipole moment vectors in the electric double layer formed through each photoconductive layer are opposite to each other, this state is referred to as the photoconductive layers 10A and 10B being charged in opposite directions.

At this time, the surface potential of the photoreceptor is determined by the amounts of primary charging and secondary charging, and by appropriately selecting these, the surface potential of the composite photoreceptor 100 after secondary charging can be set to >0.

Figure CI) shows a state in which the photoconductive layer 10A and IOB are charged in opposite directions so that the surface potential of the composite photoreceptor 10 becomes 0. A reverse charging process is realized by such primary and secondary charging.

Next, there is an image exposure step, and in the red process, this image exposure step is performed by exposing the composite photoreceptor 1 to the composite photoreceptor 1 through a filter having a spectral transmittance as shown in the curve @4-2 in Fig. 4.
This is done by irradiating the document light image onto the original document.

Then, in this image exposure process, the blue light is blocked from the composite photoreceptor 10 by the filter, so that
Composite photoreceptor! The color image I&I corresponding portion is maintained at the surface potential after secondary charging, that is, 0 potential, as in the black image corresponding portion. Further, in the areas corresponding to the white background area and the green image area, the composite photoreceptor 10 is irradiated with light, and the photoconductive layer 10A,
The charged state of both IOBs is resolved and the surface potential becomes 0 (
See Figure 1 (V)]. In addition, in the region corresponding to the red image area, the composite photoreceptor is irradiated with red light, and only the charged state of the photoconductive layer 10A, which is photosensitive to red light, is dissolved, and the surface potential at this region is The polarity becomes positive depending on the charged state of the photoconductive layer 10B. Therefore, when this image-exposed composite photoreceptor 10 is developed with a negatively charged red toner TR, a visible image corresponding only to the red image on the document 0 can be obtained with the red toner (fang 1 Figure (V)). Therefore,
This visible image is VC-transferred onto transfer paper. At that time, alignment is performed with respect to the previously transferred black visible image.

Next, the blue process will be explained.

In this blue process, the reverse charging step is the same as in the red process described above. After the reverse charging process, an image exposure process is performed. This image exposure step and the subsequent development step will be explained with reference to FIG. 1 (VI).

Image in the blue process In the lightless process, the original light image is
The composite photoreceptor 10 is irradiated with the light through a filter having a spectral transmittance as shown in the song @4-1 in FIG.

Then, due to the effect of this filter, the red light is blocked from the composite photoreceptor 10, so the photoreceptor parts corresponding to the black image area and the red image area in the original OVc are not irradiated with light, and therefore, these parts are not irradiated with light. At the location, the photoreceptor surface potential maintains the O potential after the reverse charging process.

On the other hand, in the photoconductor parts corresponding to the white background part and the green image part in the original OK, the charged state of both the photoconductive layer 10A and IOB is eliminated, and the photoconductor surface potential of these parts is also O, as in the case of the red process. becomes.

Further, the photoreceptor portion of the original O corresponding to the assigned image is irradiated with blue light, and the charged state of only the photoconductive layer 10B having photosensitivity to the back-colored light Vc is canceled, and the photoreceptor in this portion is irradiated with blue light. The surface potential becomes negative depending on the charging state of the photoconductive layer 10A.

Therefore, when development is performed with positively charged blue toner TB after the image exposure process, an evening visible image corresponding only to the blue image in document 0 is obtained, as shown in FIG. 1 (Vl). This visible image is transferred onto transfer paper.

Next, the green process will be explained.

In this green process, there is a first charge, a second charge (see Figure 1).
1), (11)) After the reverse charging process by vc, image +=a
However, in the image exposure step in the green process, a filter having a spectral transmittance as shown in track @4-6 in Figure 4 is used, so during this image exposure step, red light and blue light are , 51'j and are blocked by the composite photoreceptor 10. Therefore, the photoreceptor parts corresponding to the black image, W color image, and red image in the original OK are not irradiated with light, and in these parts, the photoreceptor surface potential remains at 0 potential due to the reverse charging process.

Now, the wavelengths that pass through the filter used in the image exposure step of this green process are substantially 500 to 55.
0 nm of light, therefore, during the image exposure process,
Of the photoreceptor parts, the parts that are irradiated with light are the part corresponding to the green surface image of document 0 and the part corresponding to the white background part.

Both of these parts are irradiated with light in the wavelength range of 500 to 550 nm, but as shown in Figure 3, the spectral reflectance of 6-1 in the white area of 51C1 is higher than that in the green image. Since the spectral reflectance is greater than 6-4, the amount of exposure light is greater in the portion of the composite photoreceptor corresponding to the white background than in the portion corresponding to the green image.

In addition, in the wavelength region of 500 to 550 nm, 1.
As is clear from Figure 2, both the photoconductive layer 10A and IOB have a spectral sensitivity of 2-1.2-3, but the photoconductive layer 10
B has relatively higher photosensitivity than the photoconductive layer 10A.

Therefore, after the reverse charging process, the composite photoreceptor has a wavelength of 500 to 500 nm.
When irradiated with 50 nm light, this light
Both EI*10A and 10B are made into conductors, but the degree of making them into conductors is greater in photoconductive layer 1[]B. Therefore, there is a difference in the speed of discharging in the photoconductive layers 10A and 10BIC, and in terms of time, the charged state of the photoconductive layer TOB is resolved first, and then the charged state of the photoconductive layer 10A is is resolved.

Therefore, referring to FIG. 6, the surface potential of the keyaki phosphor becomes D in the reverse charging process by primary charging and secondary charging. In this state, when the composite photoreceptor is irradiated with light of 500 to 550 nm, each of the photoconductive layers 10A.

Due to the difference in discharge rate between the photoconductive layers 10B and 10BK, the charged state of the photoconductive layer 10B is quickly resolved, so the photoreceptor surface potential increases as a negative potential, and then the photoconductive layer 10A becomes less charged. Along with the discharge, the surface potential increases to
K approaches.

Therefore, in the image exposure step in the green process,
Focusing on the surface potential of the photoconductor part corresponding to the blank area of document 0, the photoconductor surface potential at this part is as shown in Figure 6.
6-1.

On the other hand, at the photoreceptor portion corresponding to the green image of original O, the photoreceptor surface potential first increases to negative polarity as described above, then reverses and approaches O1i, but the green surface fl
Since the amount of bran light itself in the photoconductor part corresponding to RVC is smaller than that in the part corresponding to the white background, the change in the photoconductor surface potential is slower over time compared to that in the part corresponding to the white background. , it will be something like the song @6-2 of the 6th figure of the spear.

Therefore, by utilizing this fact, in the image exposure step in the green process, the difference between the photoreceptor surface potential Vw of the portion corresponding to the white background portion π of the document and the photoreceptor surface potential Vo of the portion corresponding to the green image portion is maximized. Image exposure is performed so that

After such an image exposure process, if development is performed with negatively charged green toner, a green visible image corresponding only to the green image mounds of document 0 can be obtained [Figure 1 (■)]. The green color process is completed by transferring this visible image onto transfer paper.

Then, if necessary, each color visible image is fixed on the transfer paper to obtain a desired four-color copy image. Note that if the development method is a wet method, a constant layer stopper is not necessary.

Hereinafter, specific examples will be described.

]・We prototyped a device as shown in Figure 5.

In the figure, numeral 100 indicates a composite photoreceptor. This composite photoreceptor 100 is drum-shaped and is rotatable in the direction of the arrow. The lamp charger indicated by the numeral 12 is a combination of a charger 12A and a red cold cathode tube 12F.

Symbol 14 (・Echarger, symbol F indicates a filter device.

Further, reference numeral 16 indicates a developing device. This developing device 16
16BK is a revolver set with a developing unit using black toner) 16BK is a developing unit using red toner 7)
16R, a developing unit 16B using back-to-back toner, and a developing unit 16G using green toner. Development can be performed by switching the order.

Reference numeral 17 indicates a pre-transfer charger, reference numeral 18 indicates a transfer drum, and reference numeral 20 indicates a transfer charger. Transfer drum 18
The transfer system using the transfer charger 20 and the transfer charger 20 is well known in connection with color copying apparatuses.

The composite photoreceptor 100 is a prototype, and was produced as follows.

As a conductive substrate, an aluminum drum 100CY having a diameter of 80 mm was used, and As28e5 was vapor-deposited to a thickness of 60 μm on the outer peripheral surface thereof to form a photoconductive layer 100B. This light guide layer 100B is the song @2-2 in Figure 22.
It has a spectral sensitivity as follows.

This As2Se3 layer was overcoated with phenol resin to a thickness of 11×n by a dipping method, and this was used as an intermediate layer for hole trapping.

On this intermediate layer, a eutectic OPC*25 .mu.m thick dipin dipping method was coated to form a photoconductive layer of 1 .mu.OA.

This eutectic OPC contains 3.9 g of 4'-(P-dimethylaminophenyl)-2,6-siphenylthiapyrylium perchlorate as a dye, 386 g of polycarbonate as a binder, and 4.4'- as a transfer agent. Screw(
It has a composition consisting of 260 g of diethylaminoco-2,2'-dimethyltriphenylmethane, 0.12 g of silicone oil as a peel preventer, 1 soo ml of dichloroetha and 1000 ml of form.

In addition, a photoconductive layer 100A &D made of this eutectic ○PC,
Spectral sensitivity like song @2-1 in Figure 2? and has a spectral transmittance as shown by curve 2-6 in FIG. Therefore, the photoconductive layer 100B alone has a panchromatic spectral sensitivity 11t'r as shown by curve 2-2 in the tF2 diagram, but when the photoreceptor 100K is irradiated with white light, the photoconductive layer 100A
The spectral intensity of the light that passes through the photoconductive layer 100B and reaches the photoconductive layer 100B is limited by the spectral transmittance 2-6 of the photoconductive layer 100A. It provides spectral sensitivity in the body.

Now, the filter device F has four filters F'1.
F2. F5. F4 are deployed and selectively Kl,l! By using this, it is possible to make the image non-lighting based on one image of original light LVc. A so-called clear filter is used as the filter F1, and a filter F2 is used as the filter F1.
The spectral transmittance of filter F60 is defined as curve 4-2 in Figure 4, and the spectral transmittance of filter F60 is determined as curve 4-2 in Figure 4.
1, and the spectral transmittance of filter F4 was determined as shown in Figure 4, song @4-3.

First, move toward the composite photoreceptor 100 in the direction of the arrow 10011111.
/SeC while rotating at the circumferential speed of lamp charger 1.
The red cold negative tube 12B of No. 2 is made to emit light, and the charger 12
+6 to A. OKV was applied to perform primary charging to 800 V on the surface of the photoreceptor 1000. Subsequently, a charger 14VC-5.5KV was applied to perform secondary charging, and the surface potential was set to -700V.

Image exposure using a light image of the original was performed using filter F1. As a result, the surface potential of the photoreceptor portion corresponding to the black image of the original is -650V, red, and blue.

The voltage was -200 to -300V in the area corresponding to the green image, and -50V in the area corresponding to the white background.

Therefore, development was carried out using the developing unit 16BK using black toner at a bias voltage of -350V.

The black visible image thus obtained was transferred onto transfer paper S. The transfer paper S is clamped on the transfer drum 18, and the transfer is performed by the transfer charger 20.

Subsequently, at the second rotation of the photoreceptor 1000, the lamp charger 12 performs primary charging at +7.0 KV to obtain a surface potential of +1600 V, and then the charger 14 performs secondary charging at a discharge voltage of -4.9 KV. , set the photoreceptor surface potential to 0, and filter F2
Image exposure is performed through the developing unit 16R1'.
(Development was performed using red toner.

Since this red toner is negatively charged, a discharge voltage of +5.2 KV is applied to the pre-transfer charger 17 to re-charge the visible image of the red toner to a positive polarity, and then it is placed on the transfer paper S. It was transferred in alignment with the black visible image.

At the 10006th rotation of the composite photoconductor, primary and secondary charging is performed under the same conditions as at the 2nd rotation, and the filter F6
The image is exposed through the developing unit 16B.
After developing with ! The color visible image was transferred onto transfer paper S by Vc. Needless to say, during transfer, alignment is performed with respect to the black visible image.

Note that the electrostatic bamboo image developed by the developing unit 16H [
The potential of the silent image corresponding to the red image is +700 V
, the potential of the Seidenkichi image (electrostatic a image corresponding to the f color image) developed by the developing unit 16B is -700V.

At the 10004th rotation of the composite photoreceptor, primary and secondary charging was performed under the same conditions as the 6th rotation, and then the filter F4
Images were taken through 4 lights. At this time, the voltage applied to the halogen lamp (not shown) that illuminates the original was set to 70 V (black process, red process).

When using the blue process, it is 64V) VcL.

After image exposure, the surface potential of the photoreceptor parts corresponding to the black, red, and blue image parts of the original is approximately 0, -100V in the white background part, and -400V in the green image part. there were.

Development was carried out using a developing unit 16GVC at a bias voltage of -150 .ANG., and the resulting green visible image was transferred onto the transfer paper S in alignment with the black visible@.

Thereafter, the transfer paper S is separated from the transfer drum 18, and the visible images of each color are fixed by a fixing device (not shown).
4 colors: red, back, and green; 4 colors: black, red, blue, and green, corresponding to tooth gaps.
A color copy image could be obtained.

Although not shown in Figure 5, the transfer drum 18
A static eliminating means and a cleaning means are provided between the lamp charger 12 and the lamp charger 12, and after each visible image is transferred,
The composite photoreceptor 100 was neutralized and cleaned.

Furthermore, when there was a cyan color picture on the manuscript, it was possible to copy it in green 1C, and it was also possible to copy a slightly darker yellow picture in green.

In the case of the device example shown in Figure 5, the black process, red process, blue process, and green process are combined depending on the type and number of colors of the image on the document to produce monochrome, two-color, and six-color images.
It is also possible to copy colors.

(Effects) As described above, according to the present invention, a novel four-color copying method can be provided. In this copying method, the four colors to be copied are each reproduced with separate toners, and the colors are not synthesized by overlapping toners, so each color is clear on the copied image.
Color turbidity due to color mixing does not occur.

Further, since each color visible image corresponds to the artist of each color on the original document, great precision is not required for positioning during transfer.

In addition to the method described with reference to FIG. 1, any known method may be used to charge the photoconductors 1- of the composite photoreceptor in opposite directions.

Further, when carrying out the black process, one photoconductive layer may be charged only once, and image exposure may be performed as it is.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the four-color electronic copying method of the present invention, Figures 2 to 4 are diagrams for explaining the invention, and Figure 5 is an apparatus for carrying out the present invention. Figure 6, which schematically shows only the essential parts of one example, is a diagram for explaining the present invention.

Claims (1)

[Scope of Claims] A first photoconductive layer having high photosensitivity to red light, no photosensitivity to blue light, and whose photosensitivity gradually decreases from wavelength 600 nm to 500 nm, and a first photoconductive layer having high photosensitivity to blue light; Sensitivity to red light, no sensitivity to red light, wavelength 500nm to 600nm
A method for copying four-color images in different colors using a composite photoconductor having a second photoconductive layer whose photosensitivity gradually decreases over time, the first
Then, the second photoconductive layer is charged in the opposite direction, image exposure is performed using a light image of the document through a filter that transmits light with a wavelength of 550 nm or less, and the resulting electrostatic latent image is developed with a blue toner. The first and second photoconductive layers are charged in opposite directions so that the surface potential of the composite photoreceptor becomes 0, and the blue color process transfers a visible image by toner onto a transfer paper. A red process in which image exposure is performed using a light image of the original through a filter that transmits light, the resulting electrostatic latent image is developed with red toner, and a visible image with the red toner is transferred onto the transfer paper; The first and second photoconductive layers are charged in opposite directions so that the surface potential of the photoreceptor becomes 0, and the wavelength is 500 to 550 nm.
A filter that transmits light of m or a wavelength of 550~
Image exposure is performed using a light image of the original through a filter that transmits 600 nm light, and the resulting electrostatic latent image is developed with tangible A color toner (red ≠ A color ≠ blue) to form a visible image using the A color toner. is transferred onto the above-mentioned transfer paper, and only one photoconductive layer of the composite photoreceptor is charged and exposed, and the resulting electrostatic latent image is developed with black toner. A four-color electronic copying method, comprising a black process for transferring a visual image onto the transfer paper, and aligning the visible images with each other when transferring the visible images of each color.