JPS61163349A - Color image recording method - Google Patents

Abstract

PURPOSE:To prevent the generation of a color deviation in a recording color image and to permit the reduction in the size of a recorder by using two photosensitive layers having respectively two photoconductive layers and making conductive one photosensitive body by chromatic A and B color light and the other by C and D color light, respectively. CONSTITUTION:The one photoconductive layer of the 1st photosensitive body 10 of the two photosensitive bodies 10, 20 constituted by providing further the 2nd photoconductive layers 10-3, 20-3 onto the 1st photoconductive layers 10-2, 20-2 provided on substrates 10-1, 20-1 is made conductive by the irradiation of the A color light and the other photoconductive layer is made conductive by the irradiation of the B color light thereto. One photoconductive layer of the 2nd body 20 is made conductive by the irradiation of the C color light thereto and the other photoconductive layer is made conductive by the irradiation of the D color light thereto. The 1st and 2nd photoconductive layers of the bodies 10, 20 are charged in the directions reverse from each other to obtain the prescribed surfaces. The alpha and beta color images are written in the form of dots by the A and B color light onto the body 10 where the three primary colors are designated as alpha, beta, gamma. The images are developed by the alpha color toner and the prescribed color light is uniformly irradiated on the photosensitive body to invert the polarity of the potential on the surface thereof and thereafter the images are developed by the beta color toner. The images on the body 20 are similarly developed by the gammacolor and black toners and these images are transferred and fixed onto the recording sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color image recording method, and more particularly to a color image recording method using a photoconductive photoreceptor.

(Prior Art) As a color image recording method in which color image information is written onto a photoconductive photoreceptor using light, a method disclosed in Japanese Patent Laid-Open No. 59-67559 is known.

However, this method has the problem that the image information of each of the three primary colors and the black image are written on separate photoreceptors, so four photoreceptors are required, which increases the size of the recording apparatus.

Further, in order to transfer the visible images formed on four photoreceptors to the same recording paper, mutual alignment of the visible images during transfer of the visible images is required three times. This makes accurate alignment difficult and recording colors.

Another problem is that color shifts tend to appear in images.

(Purpose) The present invention has been made in view of the above-mentioned circumstances, and its purpose is to enable miniaturization of a recording device and to reduce the occurrence of color shift in recorded color images. The object of the present invention is to provide a new color image recording method.

(composition) The present invention will be explained below.

The color image recording method of the present invention uses two photoreceptors. These two photoreceptors are referred to as first and second photoreceptors, respectively.

Both the first and second photoreceptors have a first photoconductive layer provided on a conductive substrate, and a second photoconductive layer provided on the first photoconductive layer directly or via an intermediate layer. It has a similar configuration. An intermediate layer is provided for charge trapping if necessary.

When the first photoreceptor is irradiated with chromatic A color light, one photoconductive layer becomes mainly conductive, and chromatic B color light (B≠
The other photoconductive layer is prepared so that it becomes mainly conductive when irradiated with A). In addition, when the second photoreceptor is irradiated with chromatic C color light, one photoconductive layer becomes mainly conductive, and when irradiated with chromatic D color light CD'1FC), the other photoconductive layer becomes mainly conductive. Prepared so that The C color light may be A color light, and the D color light may be B color light. In other words, the first and second photoreceptors may be the same.

This will be explained below with reference to FIG. Note that for the sake of concreteness of explanation, the three primary colors α, β, and γ are assumed to be cyan, magenta, and yellow, respectively.

Now, in FIG. 1, the reference numeral 10 ((■) in FIG. 1) indicates the first photoreceptor, and the reference numeral 20 ((■) in FIG. 1) indicates the second photoreceptor.

The photoreceptor 10 has a structure in which a first photoconductive layer 10-2 and a second photoconductive layer 10-3 are laminated on a conductive substrate 10-1, and A color light is applied to the photoreceptor 10. The second photoconductive layer 10-3 and the first photoconductive layer 10-2 are prepared to be mainly conductive when irradiated with B color light, respectively.

On the other hand, the second photoreceptor 2o is placed on the conductive substrate 2o-1.
It has a structure in which the first photoconductive layer 20-2 and the second photoconductive layer 20-3 are laminated, and when the photoreceptor 2o is irradiated with C color light, the photoconductive layer 20-2 Further, when irradiating with D color light, the photoconductive layers 2o-3 are prepared to be mainly conductive.

Now, when the photoreceptor 10 is uniformly irradiated with B color light, the first
Since the photoconductive layer 10-2 becomes a conductor, if corona discharge of a predetermined polarity, for example, negative polarity, is applied in this state, the first
As shown in Figure (I), an electric double layer is formed via the photoconductive layer 10-3. This state is referred to as the photoconductive layer 10.
-3 was charged. In this manner, the photoreceptor is negatively charged until the surface potential reaches -2000V, for example. This process is called primary charging. Note that if holes are easily injected from the conductive substrate 10-1 to the photoconductive layer 10-2, uniform irradiation with B color light during primary charging is not necessary.

Next, secondary charging with a polarity opposite to that of the primary charging is performed in the dark to cancel out a portion of the negative charge caused by the primary charging on the surface of the photoreceptor 10. The positive charges on the interface between the photoconductive layers 10-2 and 10-3 become excessive, and the negative charges corresponding to the excess positive charges (holes) are transferred between the conductive substrate 10-1 and the photoconductive layer 10-. As shown in FIG. 1, the photoconductive layer 10-2.
A state in which an electric double layer is formed is realized through 10-3. In this state, both of the photoconductive layers 10-2 and 10-3 are charged, according to the above expression. However, since the directions of the dipole moment vectors in the electric double layer formed through each photoconductive layer are opposite, this state is referred to as the state in which the photoconductive layers 10-2 and 10-3 are oriented in opposite directions. It is said that it was charged. This secondary charging is performed, for example, so that the surface potential of the photoreceptor becomes -600V.

Similarly, as shown in FIG. 1 (■), the second photoreceptor 20 also charges the photoconductive layers 20-2 and 20-3 in opposite directions.

In a state where the first and second photoconductive layers are charged in opposite directions, the surface potential of the photoreceptor 100 needs to have a finite developable potential, for example, the above-mentioned 1600V. On the other hand, there is no particular restriction on the surface potential of the photoreceptor 20, and the photoreceptor surface potential may be 0 in a state where the two photoconductive layers are charged in opposite directions.

Next, an α color image and a β color image, that is, a cyan color image and a magenta color image, are written in a dot shape on the photoreceptor 10 using A color light and B color light. For this writing, an optical scanning method using deflection of a laser beam, a method using an LED array, etc., which will be described later, can be used.

The color image OR to be recorded now is black, white, red, blue, green, cyan, and magenta, as shown in FIG. 1(m).

Assume that the image has image components of each color of yellow.

At this time, the cyan image is an image component obtained by color-separating the chromatic image in the color image OR using a red filter, and specifically includes a green image component, a blue image component, and a cyan image component. is a set of

Similarly, the maze/red color image is an image component obtained by color-separating the chromatic image of the color image OR using a green filter, and specifically includes a red image component, a blue image component, and a magenta color image. It is a collection of components.

Furthermore, the γ color image to be described later, that is, the yellow color image in the example currently being described, is an image component obtained by color-separating the chromatic image of the color image OR with a blue filter, and specifically, the red image component, a green image component, and a yellow image component.

It goes without saying that the black image component of the color image OR is a black image.

Now, the cyan image is written in a dot shape using the A color light. That is, the cyan image is divided into pixels, and the pixel portions that are not the cyan image are irradiated with A color light in a dot shape.

Specifically, the photoreceptor portions corresponding to the black image portion, white image portion, red image portion, magenta color image portion, and yellow color image portion are irradiated with A color light. In the area irradiated with A color light, the photoconductive layer 10-3 mainly becomes a conductor, the charged state of the photoconductive layer 10-3 is eliminated, and the photoreceptor surface potential in this area changes from 1600V to, for example, +600V. Reverse polarity.

On the other hand, a maze/red color image is written in a dot shape with B color light, and pixel portions that are not magenta color images are irradiated with B color light in a dot shape. That is, the black image portion, the white image portion, the green image portion, the cyan image portion, and the yellow image portion are irradiated with B color light. At the part of the photoreceptor irradiated with the B color light, the charged state of the photoconductive layer 10-2 is released, and the surface potential of the photoreceptor at this part becomes -1200V, for example, depending on the charged state of the photoconductive layer 10-3. In addition, A
In the areas irradiated with colored light and B color light, that is, the black image area, the white image area, and the yellow image area, the charged states of the photoconductive layers 10-2 and 10-3 are both eliminated,
Therefore, the surface potential of the photoreceptor becomes 0 at this location (first
Figure (■)).

Next, as shown in FIG. 1 (IV) K, positively charged cyan toner, that is, cyan toner T
When developed with c, a cyan image is visualized. Thereafter, when the photoreceptor 10 is uniformly irradiated with light of a predetermined color, that is, color A light in this case, as shown in FIG. This is resolved, and the photoreceptor surface potential has only a positive polarity distribution. That is, the polarity of the potential of the blue image portion in the cyan image is reversed to, for example, +600V. Therefore, if development is performed with a maze/red toner TAI which is negatively charged and has a polarity opposite to that of the cyan toner Tc, a magenta image is visualized as shown in FIG. 1 (Vl).

The visible image thus obtained on the photoreceptor 10 is shown in FIG.
), the image is transferred onto a sheet-like recording medium such as paper, that is, a recording sheet S.

On the other hand, as mentioned above, each photoconductive layer 20 of the photoreceptor 20
~2.20-3 are also charged in opposite directions (first
Figure (■)). Therefore, a black image and a yellow image are written onto the photoreceptor 20 using C color light and D color light. In this example, the black image is written with D color light, and the yellow color image is written with C color light, each in a dot shape (first
Figure (■)). That is, parts of the photoreceptor other than the pixels corresponding to the black image of the color image OR are irradiated with D color light in a dot shape, and the charged state of the photoconductive layer 20-3 is released. Further, the photoreceptor parts other than the pixels for the yellow image are irradiated with C color light in a dot shape, and the charged state of the photoconductive layer 20-2 is released.

As a result, the electrostatic latent image corresponding to the black image is formed by a negative surface potential distribution (depending on the charging state of the photoconductive layer 20-3), and the electrostatic latent image corresponding to the yellow image is formed by the positive polarity surface potential distribution. (depending on the charging state of the photoconductive layer 20-2). Therefore, the negatively charged black toner TN and the positively charged yellow toner T
, to develop these electrostatic latent images.
), and the two-color visible image thus obtained is transferred onto the recording sheet S. At this time, the previously transferred visible image and the newly transferred visible image are aligned. Then, a desired color image can be obtained as a toner image on the recording sheet S (FIG. 1 (XI)), and by fixing this on the recording sheet S, a desired recorded color image can be obtained. I can do it.

Specific examples will be described below.

Two aluminum drums with a radius of 4 Qmm are prepared, and these are used as conductive substrates.
An alloy (Tg 6 wt %) was deposited to a thickness of 60 ttm and served as the first photoconductive layer. On top of this, a second photoconductive layer made of eutectic OPC was formed to a thickness of 20 μm by a dipping method. This second photoconductive layer is a charge generating layer (
The CGL has a structure in which a charge transport layer (CTL) and a charge transport layer (CTL) are laminated, and the CGL has a structure as shown in FIG.
The CTL provided above has a structure as shown in FIG. In this way, two identical photoreceptors were obtained, and these were designated as the first and second photoreceptors.

The first photoconductive layer (deposited layer of Be-Tg) in these photoreceptors has a spectral sensitivity as shown by curve 5-1 in FIG. On the other hand, the second photoconductive layer (eutectic OPC layer) has a spectral sensitivity as shown in curve 5-2 in FIG. 5, and a spectral transmittance as shown in curve 5-3 in FIG.

Using these two photoreceptors, an apparatus as shown in FIG. 2 was constructed. Photoconductor 100 is a first photoconductor, and photoconductor 200 is a second photoconductor.

The photoreceptors 100 and 200 were arranged parallel to each other with a distance between their axes of 251,771 m. This center distance is 251 mm.
is equal to the circumference of each photoreceptor.

Around each photoreceptor, a charger 102 for primary charging,
202. Charger 104 for secondary charging. 204,
Optical writing device 106.206, developing device 108.208.
112°212, pre-transfer charger 114.214
, transfer charger 115.215, static elimination lamp 116
．． 216, cleaning device //J', zt7 were correspondingly provided, and a belt 210 for conveying the recording sheet and a fixing device 250 were also provided. In addition, the developing device 108
A fluorescent lamp 110 that emits green light was installed between and 112.

The photoreceptors 100, 200 and the belt 210 can each rotate in the direction of the arrow, but the circumferential speeds due to rotation are equal to each other. Further, the developing device 108.11 for the photoconductor 100
2, the former uses cyan toner, and the latter uses magenta toner. Further, the developing device 208 uses black toner, and the developing device 212 uses yellow toner. These developing devices 108.112.208
．． The developing method of No. 212 is a mag brush method. Note that during development, the developing devices 112 and 212 need to perform soft-touch development so as not to disturb the previously formed visible image. (This is important because the adhesion of the cyan toner is reduced by the previous green light irradiation.) However, in addition to the above-mentioned mag brush method, there are other developing methods that can perform this kind of soft-touch development. method, jumping development method, etc.

The optical writing devices 106 and 206 have the same configuration, and to explain the optical writing device 106 as an example, as shown in FIG.
1.1062, modulator 1063.1064, mirror 10
65, half mirror 1o66, beam expander
1067, Scanner 1068 with rotating polygon mirror, f
The θ lens 1069 is composed of a large number of lenses.

The light source 1061 is a Hg-Ne laser light source and emits a laser beam with a wavelength of 633 nm (red). light source 1
062 is a He-Cd laser light source with a wavelength of 442
Emits an nWL (blue) laser beam. Modulator 10
63 and 1064 are, for example, acousto-optic elements, which turn on and off the laser beam in accordance with the applied image signal. The image signal is obtained, for example, by color-separating and reading a color original.

The laser beams exiting the modulators 1063 and 1064 are combined into one laser beam by a mirror 1065 and a half mirror 1o66, and then sent to a beam expander 1067.
The diameter of the luminous flux is expanded by
Due to the action of the fθ lens 1069, it is focused into a spot, and when the rotating polygon mirror of the scanner 1068 rotates, the photoreceptor 10
Light scanning is performed by repeating 0 in the generatrix direction.

Now, as shown in Figure 5, with a wavelength of 442 nm,
The light from the Hg-Cd laser light source passes through the second photoconductive layer and turns only the first photoconductive layer (Sg-Tg alloy layer) into a conductor. On the other hand, light with a wavelength of 663 nm from the Hg--Ne laser light source turns only the second photoconductive layer (eutectic opcO layer) into a conductor.

A color image recording process using the apparatus shown in FIG. 2 will be described below. When the device is operated, first, the photoreceptor 100
, 200, and the belt 21o each start rotating at the same peripheral speed in the direction of the arrow.

First, the chargers 202 and 204 operate to perform primary charging and secondary charging on the photoreceptor 200K, thereby charging each photoconductive layer in opposite directions. The primary charging is performed so that the surface potential of the photoreceptor is -2000V, and the surface potential after secondary charging is set to OV.

If we consider each photoreceptor as a capacitor, the first photoconductive layer is +
1000 V, the second photoconductive layer would have been charged to -too v.

Subsequently, a black image is written with laser light (f color) from an Hg-Cd laser light source, and only the pixel portions of the black image are irradiated with light to form an electrostatic latent image with a potential distribution of -1000V. On the other hand, when writing a yellow image, Ha
- Laser light (red) from a Ne laser light source is used to irradiate only the pixel part of the yellow image, and +10
An electrostatic latent image is formed with a potential distribution of 00V. The image signal used was one obtained by reading a color original.

This writing method is different from the writing method described with reference to FIG. 1 (IX). In this way, various optical writing methods are possible.

The electrostatic latent image thus formed is transferred to the developing device 208 and 212.
A two-color visible image of black and yellow is obtained on the photoreceptor 200. This two-color visible image is transferred to the pre-transfer charger 214.
The charging polarity is unified to positive polarity.

Transfer paper S1 (plain paper) serving as a recording sheet is conveyed by a belt 210 at an appropriate timing, and the two-color visible image is transferred by a transfer charger 215. After the visible image has been transferred, the photosensitive weight OO is neutralized by a static eliminating rung 216.
Further, residual toner is removed by a cleaning device, and the sheet is ready for further use.

On the other hand, regarding the photoconductor 100, 1
Secondary charging is performed, and the first photoconductive layer is charged to +60
0 V, the second photoconductive layer is charged to -1200V. Therefore, after secondary charging, the surface potential of the photoreceptor 1000 is -6
It becomes 00v.

Next, after starting writing to the photoconductor 200, the photoconductor 200
After waiting for one rotation of the photoreceptor 100, writing of the cyan image and magenta image onto the photoreceptor 100 is started. Photoreceptor 10
0,200, the writing position is at the top of the circumferential surface of the photoreceptor, and the transfer position is at the bottom. And a photoreceptor 100,
The interaxial distance of 200 is equal to the length of these photoreceptors. Therefore, as described above, the start of optical writing on the photoreceptor 100 is
When the photoconductor 200 is shifted by one rotation with respect to the start of writing on the photoconductor 200, the transfer charger 115 causes the photoconductor 100 to
When the upper visible image is transferred onto the recording note S1, it will be self-aligned with respect to the previously transferred black-yellow two-color visible image.

Now, when a negative polarity one (corresponding to a cyan image) of the electrostatic latent image obtained by writing is developed with cyan toner (positively charged), green light emitted by the fluorescent lamp 110 is emitted. Uniform irradiation is performed, the charged state of the second photoconductive layer is released everywhere, and the polarity of the surface potential is reversed to positive polarity. Subsequently, the developing device 112 performs development using magenta toner. After unifying the polarity of the thus obtained visible image to positive polarity using a pre-transfer charger,
This visible image is transferred to the transfer paper S by the transfer charger 115.
Transfer to 1.

The transfer paper S1 is conveyed as it is to the left by the belt 210, and after the visible image is fixed by the fixing device 250, it is discharged from the apparatus. Photoreceptor 100 after visible image transfer
After the static electricity is removed by the static elimination lamp 116, the cleaning device 118 cleans it.

According to experiments, the circumferential speed of the photoreceptors 100 and 200 was set to 80 r.
ILnL/l! It was possible to obtain 10 A4 size color image records per minute. No color shift was visually observed in the recorded color images obtained.

One of the reasons why there is no color shift is that the visible images are aligned only once, which enables highly accurate alignment.In addition, in the case of this example, , other causes are also at play. Generally black, cyan, magenta,
When a color image is obtained by superimposing toner images of each color of yellow, the color shift that is most noticeable is the color shift between the cyan image and the magenta image. In the above embodiment, the cyan image and the magenta image are formed on the same photoreceptor, and color misregistration between these visible images may occur during transfer, so this also helps prevent color misregistration. It used to be.

(Effects) As described above, according to the present invention, a novel color image recording method can be provided. In this method, since two photoreceptors are used, the recording apparatus can be made smaller and lower in cost. Furthermore, since the mutual alignment of visible images during transfer only needs to be done once, highly accurate alignment is easily possible and color shift can be effectively prevented.

Furthermore, miniaturizing the device leads to a reduction in the travel distance of the recording sheet, thereby improving recording efficiency.

Note that in the embodiment shown in FIG. 2, the order of transferring the visible images is opposite to the order explained for FIG. 1, but the order of transfer is as follows: Good too.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention, FIG. 2 is an explanatory front view showing an example of an apparatus for carrying out the present invention, and FIGS. 3 to 5 are the same as those in FIG. FIG. 6 is a diagram for explaining the photoreceptor in the embodiment, and FIG. 6 is a diagram for explaining the optical writing device. DESCRIPTION OF SYMBOLS 10... First photoreceptor, 10-1... Conductive substrate, 10-2... First photoconductive layer, 1o-3...
- Second photoconductive layer, 20... second photoreceptor, OR...
・Color image to be recorded, A...A color light, B
...B color light, C...C color light, D...D color light,
To...Cyan t+, 'rM...Magenta toner, TY...Yellow toner, TN...
Black toner, S...recording sheet.

Claims (1)

[Claims] Two photosensitive materials having a structure in which a first photoconductive layer is provided on a conductive substrate, and a second photoconductive layer is provided on the first photoconductive layer directly or via an intermediate layer. Among the bodies, the first photoreceptor is A
When irradiated with colored light, one photoconductive layer is exposed to B colored light (B≠A
) is prepared so that the other photoconductive layer is mainly made into a conductor, respectively, and the second photoreceptor is prepared so that one photoconductive layer is made mainly conductive by light irradiation with C color light (C=A or C≠A). is prepared so that the other photoconductive layer is mainly made into a conductor by irradiation with D color light (D≠C, D=B or D≠B), and these first and second photoconductive layers In each body, when the first and second photoconductive layers are charged in opposite directions to set the photoreceptor surface potential to a predetermined potential, and the three primary colors are α, β, and γ, the first photoreceptor For this purpose, an α color image and a β color image are written in the form of dots using A color light and B color light, and after development with α color toner, uniform irradiation is performed with light of a predetermined color to change the polarity of the photoreceptor surface potential. The image is reversed and developed with β color toner charged to the opposite polarity to the α color toner, and the γ color image and black image are formed into dots on the second photoconductor using C color light and D color light, respectively. Write, γ
An electrostatic latent image corresponding to a color image and an electrostatic latent image corresponding to a black image are formed as surface potential distributions with opposite polarities, and these electrostatic latent images are converted into gamma color, which is charged with opposite polarities. A color image recording method characterized by developing with toner and black toner, and aligning and transferring visible images formed on each photoreceptor onto the same recording sheet and fixing them.