JPH03202868A - Full-color image forming method - Google Patents

Abstract

PURPOSE:To form an excellent full-color image in a single image forming process by forming electrostatic latent images corresponding to respective colors and electrostatic latent images for neutralization different in polarity in the same shape on the photoconductive layer on a compound photosensitive body, and eliminating image appearance on a surface temporarily. CONSTITUTION:The photosensitive drum has the photoconductive layer sensitive to light beams each different in wavelength, and an L, an M, and a U layer are laminated on an electrode 1a. The layers L, M, and U are charged electrostatically to have alternate potentials in the lamination order. At this time, the layers L, M, and U are exposed to pieces of luminous flux which have wavelengths corresponding to the photosensitivity values of the photoconductive layers while containing pieces of image information corresponding to the respective colors at the same time to form the electrostatic latent images corresponding to the colors and electrostatic latent images for neutralization different in polarity in the same shape. The electrostatic latent images for neutralization serve to prevent the electrostatic latent images from appearing on the surface until the end of process. Then the photosensitive drum is exposed uniformly to the pieces of wavelength light flux lambda1, lambda2 and lambda3 and thus potential distributions corresponding to the respective color electrostatic latent images are developed with respective color toner particles while visualized on the surface part of the compound photosensitive body. Thus, the full-color image formation can securely be performed in the single forming process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a full-color image forming method using a composite photoreceptor formed by laminating a plurality of photosensitive layers sensitive to light of different wavelengths.

(Prior Art) In general, in various full-color image forming devices such as copiers and printers that form full-color images, electrostatic latent images corresponding to each color image are formed on a photoreceptor, and a color developing device A two-component type or one-component type developer is held on a developing roller provided in the I, and the color toner in this developer is in the area facing the photoreceptor.
A developing operation is performed by being supplied to the electrostatic latent images of each color in the R body region. The visible toner images of each color obtained by development are superimposed on each other and transferred to the recording paper side, thereby producing a full-color image.

A full-color image forming method using such a general image forming apparatus involves forming a color image for each color on a plurality of photoreceptors (for example, a four-drum photoreceptor) (Japanese Unexamined Patent Application Publication No. 1983-1993). 38966, etc.),
One photoreceptor is conveyed over multiple cycles corresponding to each color image (Japanese Patent Laid-Open No. 58-7815
No. 7, etc.), or one in which a photoreceptor with a mosaic filter is uniformly exposed and the electrostatic latent images of each color are sequentially recalled and developed (Japanese Patent Laid-Open No. 58
-82270, etc.) have been proposed in the past.

(Problem to be Solved by the Invention) However, the apparatus configured to carry out such a conventional full-color image forming method has a complicated structure and high cost, and the color density of the formed image is low. It has not been possible to stably obtain a good full-color image due to a decrease in color density or a shift of one color.

On the other hand, a full-color imprinting method has been proposed in which an electrostatic latent image corresponding to each color is formed on each photoconductive layer of a composite photoreceptor made of five laminated photoconductive layers (Japanese Patent Application Laid-Open No. 59-121
According to this full-color image forming method, it is theoretically possible to form a full-color image using only Wang Kai's image forming apparatus with a simple structure. . However, it is actually difficult to create a full-color image using this method, and there are problems in putting it into practical use.

Therefore, an object of the present invention is to provide a full-color image forming method that can form high-speed, high-quality ** images using a small, low-cost device, and that can be easily implemented. do.

(Means for Solving the Problems) In order to achieve the above object, the invention described in claim 1 is such that after uniformly charging a photoconductive layer of a photoreceptor to a predetermined potential, image information for each color is generated. In a full-color image forming method, the electrostatic latent images corresponding to each color image are formed by performing haze light writing, and the electrostatic latent images corresponding to each color image are developed with each color toner to obtain a full color image. Each photoconductive layer of a composite photoreceptor is formed by laminating three photoconductive layers that are sensitive to light of different wavelengths, and each photoconductive layer is exposed in the dark or selectively and uniformly to light of a predetermined wavelength. A process of charging the conductive layers to a predetermined potential so that they have alternating polarities in the stacked order, and simultaneously exposing images and information corresponding to each color to light of each wavelength corresponding to the photosensitivity of each photoconductive layer. As a result, electrostatic latent images corresponding to each color and neutralizing electrostatic latent images of different polarities and the same shape to temporarily prevent the electrostatic latent images corresponding to each color from coming to the surface are formed on each of the three photoconductive layers. By forming the respective electrostatic latent images and selectively and uniformly exposing them to light of a predetermined wavelength, a potential distribution corresponding to each color electrostatic latent image is made visible on the surface of the composite photoreceptor, and corresponding to each color electrostatic latent image. The method includes a step of sequentially supplying toner of each color and performing development to obtain a full-color toner visible image.

Further, the invention described in claim 2 is a method for forming an electrostatic image corresponding to each color in the full-color image forming method described in claim 1, and the electrostatic latent images corresponding to each color are not temporarily brought to the surface. The electrostatic latent images for neutralization having different polarities and the same shape are visualized by a negative-positive reversal development method in which toner is attached to the light irradiated area.

(Function) In the means provided with the configurations described in claims 1 and 2, full-color image formation is reliably performed by only one image forming process.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 4 shows a full-color copying machine as an example of an apparatus for carrying out the present invention. Around the photoreceptor drum 1, along the rotation direction (clockwise direction in the figure),
A charger that performs initial charging of the photoreceptor drum 2. A digital exposure system (not shown) (the exposure optical path is indicated by reference numeral 3) that forms each electrostatic latent image on the photoreceptor drum 1, and a cyan developing device 4 that develops the electrostatic latent image corresponding to cyan. A static elimination lamp 5 removes an electrostatic latent image corresponding to cyan, a magenta developing device [6] develops an electrostatic latent image corresponding to magenta, a static elimination lamp 7 removes an electrostatic latent image corresponding to magenta, a static elimination lamp 7 corresponds to yellow. Yellow developing device that develops electrostatic latent images! 8. A pre-transfer charger that adjusts the charging state of each color toner attached to the photoreceptor drum 1 side during development.9. Transfer charger 11 for transferring a visible toner image onto recording paper. A cleaning device 12 and the like for removing toner remaining on the photoreceptor drum 1 after transfer are arranged.

As shown in FIGS. 1 and 2, the photoreceptor drum 1 includes three
It has a photoconductive layer as a body, and an L layer, an M layer, and a U layer are laminated in this order from the inside on an electrode la as a base. The L layer consists of a selenium (Ss) layer deposited on the electrode la,
It has photosensitivity to blue light (wavelength λi). In addition, the M layer is a microcrystalline dispersed OPC overcoated on the L layer.
It has photosensitivity to red light (wavelength λ2). The U layer is composed of a functionally separated OPC formed by overcoating CTL and CGL on the L layer by a spray method, and has photosensitivity to near-infrared light (wavelength λ). At this time, light with wavelength λ1 passes through the M layer and U layer, and light with wavelength λ2 passes through the U layer. The above layer is used with positive charge, and the M layer is used with negative charge.

The U layer is used with positive charge, and the capacitance of each layer is set to be equal to each other.

Returning to FIG. 4, corresponding to the configuration of the photosensitive drum 1, the charger 2 includes a primary charger 2a equipped with a lamp that uniformly exposes light with a wavelength λ and light with a wavelength λ2; a secondary charger 2b equipped with a lamp that uniformly exposes the light of;
It consists of a tertiary charger 2c that does not include an exposure lamp, and a static elimination lamp 5 that removes an electrostatic latent image corresponding to cyan, and a lamp that uniformly exposes light of wavelength λ, and removes an electrostatic latent image corresponding to magenta. The static elimination lamp 7 that removes the light is composed of a lamp that uniformly exposes light with a wavelength of λ.

In addition, the exposure system (not shown) has a wavelength of λ0. λ2. It is configured to simultaneously emit laser light with three wavelengths of λ3, and the exposure action of this produces cyan, magenta, and
Three yellow electrostatic latent images are written on the photosensitive drum l at the same time. At this time, the wavelength λ,
The light is set at 442 nm, and is emitted from a He-Cd laser, and the wavelength is λ2.
The light with wavelength λ is set to 680 nm and is emitted from the semiconductor laser, and the light with wavelength λ is set to 780 nm and is emitted from the semiconductor laser.

Next, an image forming process in an embodiment of the present invention using such an apparatus will be described.

First, as shown in FIG. 1(a), -number charger 2
The photoreceptor drum 1 is primarily charged with a positive corona while being uniformly exposed to light of wavelength λ and light of wavelength λ2 by a. As a result, only the L layer is charged to +1500V, and the surface potential of the photosensitive drum 1 is also set to +L500V (see point a in FIG. 3).

Next, as shown in FIG. 1(b), the secondary charger 2b uniformly exposes the photoreceptor drum 1 to light having a wavelength λ while the photoreceptor drum 1 is secondary charged with a negative corona. The charge density of the negative corona at this time is 4
As a result, the M layer is negatively charged and the surface potential of the photosensitive drum 1 is set to -2500V (see the point in Figure 3).

Furthermore, tertiary charging is performed in the dark by the positive corona of the tertiary charger 2C. At this time, the charge density of the positive corona is 2/3 that of the positive corona in the primary charging, so that the U layer is negatively charged. As a result, the L layer is charged to +500V, the 1M layer is charged to 11000V, and the U layer is charged to +100V.
At this time, the surface potential of the photosensitive drum 1 is set to +5 oov (see point C in FIG. 3).

+500V in the above layer is for forming a yellow electrostatic latent image, -5oov in one 1000V of the M layer is for forming a magenta electrostatic latent image, and the remaining 500V is for forming a yellow electrostatic latent image. It is. This negative yellow electrostatic latent image in the M layer is the same as the positive yellow electrostatic latent image forming in the L layer, and has the role of not allowing it to surface until the end of the process. Similarly, +500V in the +100OV of the U layer is for forming a cyan electrostatic latent image, and the remaining +500V is for forming a positive magenta electrostatic latent image to neutralize the negative magenta electrostatic latent image of the M layer.

When the photosensitive drum 1 is brought into such a charged state, λ
4. λ2. Light images corresponding to three colors, cyan, magenta, and yellow, are simultaneously exposed and written using laser light having three wavelengths of λ.

That is, the light with wavelength λ carries yellow image information, the light with wavelength λ2 carries yellow image information and magenta image information, and the light with wavelength λ,
The light carries magenta image information and cyan image information. And what is light with wavelength λ2 and light with wavelength λ1? Exposure is performed with the output of λ, and the light of wavelength λ is
Exposure is performed with an output of /2, and on the other hand, each of the 1M layer and the U layer has an optical attenuation of 100 OV with the output I0, and a 500 V optical attenuation with the output I0/2. It is now possible to do this.

Table 1 shows the relationship between the original image (color) and the output of each laser at this time.

Table 1 The charge distribution after such exposure is shown in FIG. 2(a).

(B), (C) 0 As shown in the figure, Black, Cyan
.

The pixels corresponding to each color of green and blue are set to a surface potential of +500V (point d in Figure 3), and the pixels corresponding to each color of magenta,
The pixels corresponding to each of the colors yellow, red, and white are set to the surface potential of OV (see point d' in FIG. 3). Note that in FIG. 2, pixels corresponding to white are omitted.

First, as shown in FIG. 2(a), development is performed using negatively charged cyan toner, and black and cyan (Cy) are developed as shown by black circles.
an), Green and Blue
Cyan toner is applied to pixels corresponding to each color of ue).

Next, as shown in FIG. 2(b), after uniform exposure with light of wavelength λ (780 nm) is performed, development with magenta toner is performed. At this time, the wavelength λ3
Since more than 90% of the light passes through the cyan toner already attached, only the positively charged portion of the U layer is selectively attenuated, resulting in a charge distribution as shown in FIG. 2(b).

In other words, the positive magenta electrostatic latent image in the U layer is erased, and the negative magenta electrostatic latent image in the M layer is cursed, resulting in black,
The pixels corresponding to magenta, red, and blue are set to a surface potential of 1500 V (see point e' in Figure 3), and the pixels corresponding to the other colors cyan and green are set to a surface potential of 1500 V (see point e' in Figure 3). )
, Yellow and White
The pixels corresponding to each color of ite) are set to the surface potential of Ov (
(See point e in Figure 3).

In this state, development is performed using positively charged magenta toner, and as shown by the gray circles in FIG. 2(b), black and magenta toner
a) - Magenta toner is attached to pixels corresponding to each color of red (Red) and blue (Blue).

Furthermore, as shown in FIG. 2(c), after uniform exposure with light of wavelength λ2 (680 nm) is performed, development with yellow toner is performed. The magenta toner that has already been attached also allows the light of wavelength λ2 to pass through well.
As a result, only the negatively charged portion of the M layer is selectively attenuated by light, resulting in a charge distribution as shown in FIG. 2(C). That is, the positive yellow electrostatic latent image in the M layer is eliminated and the L
A negative yellow electrostatic latent image in the layer is cursed, which causes black, yellow
z), Red and Green
) is set to a surface potential of +500V (see point f in Figure 3), and the other color magenta (Ma
genta).

The pixels corresponding to each color of blue, cyan, and white are made to have a surface potential of Ov (see point f' in FIG. 3).

In this state, development is performed using negatively charged yellow toner, and as shown by the white circles in FIG. 2(c), black and yellow toner are developed.
), Red and Green
Yellow toner is attached to pixels corresponding to each color.

As a result, a full-color toner visible image is formed on the photoreceptor drum l.

In addition, in such 1501, development with magenta toner and development with yellow toner are preferably performed by so-called non-contact development.

The full-color toner visible image formed on the photoreceptor drum 1 is transferred and copied onto the recording paper side by the transfer charger 11, but before that, the toner composition by the pre-transfer charger 9,! 1111 is performed. In other words, after development, the cyan toner and yellow toner are negatively charged, and the magenta toner is positively charged, so the pre-transfer charger 9 is set so that the toner polarities are unified to the negative side. It has become. The transfer action by the transfer charger 11 is the same as normal corona transfer, and the transferred image is fixed on the recording paper by thermal fixation.

The full-color image obtained in this way is a high-density image with no positional deviation, and is especially true for cyan, magenta,
Even in the black image obtained by overlapping all of the yellow toners, there is no positional shift), so good reproducibility can be obtained.

Next, the embodiment shown in FIGS. 5 to 8 will be explained.

In this embodiment, a full-color copying machine shown in FIG. 8 is used. That is, around the photoreceptor drum 21, along the direction of rotation (clockwise direction in the figure), there are a charger 22 for initially charging the photoreceptor drum 21, and a charger 22 for forming an electrostatic latent image of each color on the photoreceptor drum 21. A digital exposure system (the exposure optical path is indicated by the reference numeral 23) with omitted, and a cyan developing device W124 that develops an electrostatic latent image corresponding to cyan.
, a static elimination lamp 25 that removes an electrostatic latent image for cyan, a magenta developing device 26 that develops an electrostatic latent image for magenta, and a static elimination lamp 2 that removes an electrostatic latent image for magenta.
7. A yellow developing device 28 that develops an electrostatic latent image corresponding to yellow; a pre-transfer charger 2 that adjusts a charged layer of toner attached to the photoreceptor drum 21 side by development;
9. A transfer charger 31 that transfers the toner visible image onto the recording paper, a cleaning device 32 that removes the toner remaining on the photosensitive drum 21 after the transfer, and the like are arranged.

As shown in FIGS. 5 and 6y1, the photosensitive drum 21 has three light guides 11M that are sensitive to light of different wavelengths, and is mounted on an electrode 21a as a base. An L layer, an M layer, and a U layer are laminated in this order from the inside. The L layer is selenium (Se) deposited on the electrode 21a.
It consists of layers and has photosensitivity to blue light (wavelength λL). The M layer is made of microcrystalline dispersed OPC overcoated on one layer, and has photosensitivity to red light (wavelength λ2). The U layer is composed of a functionally separated OPC formed by overcoating CTL and CGL on one layer using a spray method, and has photosensitivity to near-infrared light (wavelength λ). At this time, light with a wavelength λ passes through the M layer and the U layer, and light with a wavelength λ2 passes through the U layer. The above layer is used with positive charge, and
The M layer is used with positive and negative charges, and the U layer is used with positive charges, and the capacitance of each layer is set to be equal to each other.

Returning to FIG. 8, corresponding to the configuration of the photosensitive drum 21, the charger 22 is a primary charger 22a including a lamp that uniformly exposes light of wavelength λ2.

It consists of a secondary charger 22b that does not include an exposure lamp, and a static elimination lamp 25 that removes the electrostatic latent image corresponding to cyan, which consists of a lamp that uniformly exposes light of wavelength λ3.
The static elimination lamp 27 for removing the electrostatic latent image corresponding to magenta is composed of a lamp that uniformly exposes light of wavelength λ2.

Exposure systems not shown are λ□, λ2. λ.

It is configured to simultaneously emit laser beams of three different wavelengths, and by exposure with this, three electrostatic latent images of cyan, magenta, and yellow are simultaneously written on the photoreceptor drum 21. . At this time, the light with the wavelength λ is set to 442 nm and is emitted from the He-Cd laser, and the light with the wavelength λ2 is set to 680 nm and is emitted from the semiconductor laser. The light is set at 780 nm and is emitted from a semiconductor laser.

Next, an image forming process using such an apparatus will be explained.

First, as shown in FIG. 5(a), -water charger 2
2a, the photosensitive drum 21 is primarily charged with a positive corona while being uniformly exposed to light of wavelength λ2. As a result, the L layer and the U layer are each positively charged (charged) to +2000V, and the overall surface potential of the photoreceptor drum l is +
4000V (see point a in Figure 7).

Next, as shown in FIG. 5(b), secondary charging I
22b, the photosensitive drum 21 is exposed to negative corona in the dark.
Secondary charging is performed. Here, when the surface charge density of the photoreceptor drum 21 due to the secondary charging is Q, the surface charge density on the U layer and the electrode 21 due to the secondary charging are
The electrons induced in a are +1/2Q and −
1/2Q, +1000V to L layer and U layer, M
-100 OV is applied to the layer, and the overall potential is +1000.
V (see the point in Figure 7).

When the photosensitive drum 21 is brought into such a charged state,
λ8. λ2. Light images corresponding to three colors, cyan, magenta, and yellow, are simultaneously exposed and layered using laser light of three different wavelengths, λ.

That is, yellow image information is carried on the light of wavelength λ1, yellow image information and magenta image information are carried on the light of wavelength λ2, and further, yellow image information is carried on the light of wavelength λ3.
The light carries magenta image information and cyan image information. The light with the wavelength λ1, the light with the wavelength λ2, and the light with the wavelength λ3 are each processed separately. Exposure is performed with the output of , and this output ■. The light is attenuated by 100 OV depending on the exposure point.

However, the light of wavelength λ1 at this time carries yellow image information over the output of 6/2, and is processed independently of this. /2 output is uniformly exposed. In this way, light with wavelength λ is used. /2
As shown in FIG. 5(c), the potential of the L layer increases to +100O as shown in FIG. 5(c).
The voltage state is changed from the V state to the +500 V state.

This charging state is the same as the state after tertiary charging in the above-mentioned Embodiment I. At this time, the output ■. /2 wavelength λ,
For uniform exposure, use a separate light source from the charger! (It is also possible to irradiate with a lamp placed in the i position.

At this time, the relationship between the original image (color) and the output of each laser is shown in Table 2.

Table 2 The charge distribution after such exposure is shown in FIG. 6(a).

Shown in (b) and (c). As shown in this figure, black, cyan,
The pixels corresponding to each color of green and blue are set to a surface potential of +500V (see point C in Figure 7), and the pixels corresponding to the colors of magenta
.

The pixels corresponding to each color of yellow, red, and white are set to the surface potential of OV (see point C' in FIG. 7). At this time, for Black, the L layer is +500V.

The M layer has a voltage of 11000V, the U layer has a voltage of +100OV, and for cyan, only the U layer has a voltage of +500V. Even more green
For n), the L layer is +500V and the M layer is 1500V.
, the U layer is set to +500 V, and for Blue, the L layer is set to OV and the M layer is set to +500 V.
00V, and the U layer is set to +1000V.

First, as shown in FIG. 6(a).

Development is performed using negatively charged cyan toner, and the image is black as indicated by the black circle.

Cyan toner is applied to pixels corresponding to each color of cyan, green, and blue.

Next, as shown in FIG. 6(b), after uniform exposure with light of wavelength λ□ (780 nm) is performed, development with magenta toner is performed. At this time, the wavelength λ□
Since more than 90% of the light passes through the cyan toner already attached, only the positively charged portion of the U layer is selectively attenuated, resulting in a charge distribution as shown in FIG. 6(b).

In other words, the positive magenta electrostatic latent image in the U layer disappears, and the negative magenta electrostatic latent image appears in the M layer, and as a result, black,
The pixels corresponding to the colors magenta, red, and blue are set to a surface potential of 1500 V (see point d' in Figure 7), and the pixels corresponding to the other colors cyan, green ( Green
), Yellow and White
The pixels corresponding to each color of te) are made to have a surface potential of OV (see point d in FIG. 7).

In this state, development is performed using positively charged magenta toner, and as shown by the gray circles in FIG. 6(b), black and magenta are developed.
ta), Red and Blue
) magenta toner is applied to pixels corresponding to each color.

Furthermore, as shown in FIG. 6(c), after uniform exposure with light of wavelength λ2 (6gOn+*) is performed, development with yellow toner is performed. Since the already attached magenta toner also transmits light of wavelength λ2 well, only the negatively charged portion of the M layer is selectively attenuated, resulting in a charge distribution as shown in FIG. 6(c). Become.

In other words, the positive yellow electrostatic latent image in the M layer is erased, and the negative yellow electrostatic latent image in the L layer is cursed, resulting in black and yellow.
ow), Red and Green
The pixels corresponding to each color of n) are set to a surface potential of +500V (see point e in Figure 7), and the pixels corresponding to the other magenta (Mage
nta), Blue, Cyan
) and white (Vhite) pixels are OV
(see point e' in Figure 7).

In this state, development is performed using negatively charged yellow toner, and as shown by the white circles in Figure 6(C), black and yellow toner are developed.
), Red and Green
Yellow toner is attached to pixels corresponding to each color.

As a result, a full color toner visible image is transferred to the photoreceptor drum 21.
It will be formed on top.

Note that during such development, development with magenta toner and development with yellow toner are preferably performed by so-called non-contact development.

The full-color toner visible image formed on the photosensitive drum 21 is transferred to the recording paper side by the transfer charger 31.
Before being copied, toner authority adjustment is performed by the pre-transfer charger 29. That is, after development, the cyan toner and yellow toner are negatively charged, and the magenta toner is positively charged, and the pre-transfer charger 29 unifies the polarity of the toner to the negative side. There is. The transfer action by the transfer charger 31 is the same as normal corona transfer, and the transferred image is fixed on the recording paper by thermal fixation.

The full-color image obtained in this way is a high-density image with no positional deviation, and is especially true for cyan, magenta,
Even in a black image obtained by overlapping all of the yellow toners, there is no positional shift, so good reproducibility can be obtained.

Furthermore, the actual lost coins shown in the 9th @ to the 12th @ will be clarified.

In this embodiment, a full-color copying machine shown in FIG. 12 is used. That is, around the photoreceptor drum 41, along the direction of rotation (clockwise direction in the figure), there is a charge @ 42 for initial charging of the photoreceptor drum 41, and a charger @42 for forming an electrostatic latent image of each color on the photoreceptor drum 41. A digital exposure system (the exposure optical path is indicated by reference numeral 43), which omits the above, and a cyan developing device that develops an electrostatic latent image corresponding to cyan! 44
, a static elimination lamp 45 for removing the electrostatic latent image for cyan, a magenta developing device 146 for developing the electrostatic latent image for magenta, a static elimination lamp 47 for removing the electrostatic latent image for magenta, and a static elimination lamp 47 for removing the electrostatic latent image for yellow. A yellow image forming device 48 for developing an electrostatic latent image, a pre-transfer charger 49 for adjusting the charging state of the toner attached to the photosensitive drum 41 side by development. A transfer charger 51 that transfers a visible toner image onto a recording sheet, a cleaning device 52 that removes toner remaining on the photoreceptor drum 41 after the transfer, and the like are arranged.

As shown in FIGS. 9 and 10, the photosensitive drum 41 has three photoconductive layers that are sensitive to spring light of different wavelengths, and the electrode 41 serves as a base.
Layer L and layer 1M from the inside on a.

U layers are laminated in order. The L layer is composed of a selenium (Se) layer deposited on the electrode 41a, and is transparent to blue light (wavelength λ1).
) has photosensitivity. The M layer is made of a microcrystalline dispersed OPC overcoated on the L layer, and has photosensitivity to red light (wavelength λ2). The U layer is C on the L layer.
It consists of a functionally separated OPC made by overcoating TL and CGL using a spray method, and emits near-infrared light (wavelength λ,
) has photosensitivity. The above layers are used with negative and positive charges, the 1M layer is used with negative charges, and the U layer is used with negative and positive charges, and the capacitance of each layer is set to be equal to each other. has been done. Then, the light of wavelength λ passes through the M layer and the same layer, and
Light with wavelength λ2 is configured to pass through the U layer.

Returning to FIG. 12, corresponding to the configuration of the photosensitive drum 41, the charger 42 includes a primary charger 42a equipped with a lamp that uniformly exposes light of wavelength λ□ and light of wavelength λ3;
It consists of a secondary charger 42b that does not include an exposure lamp, and a static elimination lamp 45 that removes an electrostatic latent image corresponding to cyan, which consists of a lamp that uniformly exposes light of wavelength λ,
The static elimination lamp 47 for removing the electrostatic latent image corresponding to magenta is composed of a lamp that uniformly exposes light of wavelength λ2.

Exposure systems not shown are λ□, λ2. λ.

It is configured to simultaneously emit laser beams of three different wavelengths, and by this exposure, three electrostatic latent images of cyan, magenta, and yellow are simultaneously written on the photoreceptor drum 41. At this time, the wavelength λ is set to 442 nm, which is emitted from the He-Cd laser, and the wavelength λ2 is 68 nm.
The wavelength λ is set to 0 nm and is emitted from a semiconductor laser.

is set at 780 nm and is emitted from a semiconductor laser.

Next, an image forming process using such an apparatus will be explained.

First, as shown in FIG. 9(a), the negative charger 4
2a of light of wavelength λ1 and wavelength λ.

The photosensitive drum 1 is primarily charged with a negative corona while being uniformly exposed to light. As a result, the M layer is positively charged (charged), and the overall surface potential of the photoreceptor drum l is -2
000V (see point a in Figure 11).

Next, as shown in FIG. 9(b), the secondary charger 42b charges the photosensitive drum 41 with a positive corona in the dark.
Secondary charging is performed. Here, the surface charge density of the photosensitive drum 41 due to the above-mentioned -order charging is Q. When this happens, the surface charge density on the U layer and the electrode 41 increase due to the secondary charging.
The electrons induced in a and a become +1/2Q and -1/2Qo, respectively, and the L layer and U layer receive +1000V,
-100OV is added to the M layer, and the overall potential is +1000.
(See the point in Figure I1).

When the photosensitive drum 41 is brought into such a charged state,
λ□, λ2. Light images corresponding to three colors, cyan, magenta, and yellow, are simultaneously exposed and written using laser light having three wavelengths of λ. That is, the light of wavelength λ carries yellow image information, the light of wavelength λ2 carries yellow image information and magenta image information, and the light of wavelength λ3 carries magenta image information and cyan image information. Contains image information. The light of wavelength λ□, the light of wavelength λ2, and the light of wavelength λ□ are each exposed at an output of Io, and the outputs are different. A light attenuation of 100 OV is caused by exposure of 100 OV.

However, the light of wavelength λ at this time carries yellow image information corresponding to the output of I0/2, and is processed independently of this. /2 output is uniformly exposed. In this way, light with wavelength λ□ is processed. By performing uniform exposure over the output of /2, the image shown in Fig. 9 (c
), the potential of the L layer is changed from +100OV to +500V. This state is the same as the state after the third IS in the first embodiment.

Also, this crab. It is also possible to irradiate the light with a wavelength λ of /2 with a lamp installed as a light source separate from the *2 device.

At this time, Table 3 shows the relationship between the original image (color) and the output of each laser.

Table 3 The charge distribution after such exposure is shown in FIG. 10(a).

Shown in (b) and (Q). As shown in this figure, black, cyan,
The pixels corresponding to each color of green and blue are set to a surface potential of +500V (point C in Figure 11), and the pixels corresponding to each color of magenta,
Pixels corresponding to each color of yellow, red, and white are set to the surface potential of OV (see point C' in FIG. 11). However, at this time, the L layer of the black unit is +500V.
, M layer is 11000V, U1! F is set to +1ooov, and cyan is +500V only in the U layer. Furthermore, green (Gr.
een), the L layer is +500V and the M layer is 150V.
0V, the U layer is set to +500V, and for blue, the L layer is set to OV, and the M layer is set to +500V.
00V, and the U layer is set to +100Ov.

First, as shown in FIG. 10(a), development is performed using negatively charged cyan toner.
Black, cyan, and green as indicated by the black circles in the figure.

Toner is attached to pixels corresponding to each color of blue and blue.

Next, as shown in FIG. 10(b).

After uniform exposure with light of wavelength λ1 (780 nm), development with cyan toner is performed. wavelength λ,
Since more than 90% of the light passes through the cyan toner, only the positively charged portion of the U layer is selectively attenuated, resulting in a charge distribution as shown in FIG. 10(b). In other words, the positive magenta electrostatic latent image in the UM disappears, and the negative magenta electrostatic latent image appears in the M layer.
agent), Red (Red) and Blue (B
The pixels corresponding to each color (blue) are made to have a surface potential of 1500V (see point d in FIG. 11), and the pixels corresponding to the other color, cyan.

Pixels corresponding to each color of green, yellow, and white are set to a surface potential of Ov (see point 11 (iiid)).

In this state, development is performed using magenta toner that is positively charged, and black and magenta are developed as shown by the gray circles in FIG. 10(b).
ta), Red and Blue
Magenta toner is applied to pixels corresponding to each color.

Furthermore, as shown in FIG. 10(c), the wavelength λ2
After uniform exposure with light (680 nm), development with magenta toner is performed. Magenta toner also transmits light with wavelength λ2 well, so only the negatively charged portion of the M layer is selectively attenuated, as shown in Figure 10 (c).
) The charge distribution will be as shown in . In other words, the positive yellow electrostatic latent image in the M layer disappears and the negative yellow electrostatic latent image appears in the L layer, resulting in a black (
Black), Yellow, Red (
The pixels corresponding to each of the colors Red and Green are set to a surface potential of +500V (see point e in FIG. 11).

Other colors such as magenta, blue (
Blue), Cyan and White
The pixels corresponding to each color of ite) are made to have a surface potential of Ov (see the 11th pii e' point).

In this state, development is performed using negatively charged yellow toner, and black and yellow toner are developed as shown by the white circles in FIG. 10(c).
w) Toner is attached to pixels corresponding to each color of red (Red) and green (Green). From this point on, a full-color toner visible image is formed on the photoreceptor drum 41.

During such development, it is preferable that the magenta toner development and the yellow toner development be carried out by a so-called non-contact developer.
The full-color toner visible image formed thereon is transferred to the recording paper side by the transfer charger 51, but before that, the toner composition is adjusted by the pre-transfer charger 49. That is, after development, the cyan toner and yellow toner are negatively charged, and the magenta toner is positively charged, and the pre-transfer charger No. 49 unifies the polarity of the toner to the negative side. I'm going to cram school. Transfer action 11 by transfer charger 51 is the same as normal corona transfer, and the transferred image is fixed on the recording paper by heat fixing.

Full-color image obtained in this way 1. It is a high-density image with no misalignment at all, and even a black image obtained by superimposing all of the special cyan, magenta, and yellow toners is ti! Since there is no deviation, good reproducibility can be obtained.

Next, the embodiment shown in FIGS. 13 to 15 will be described.

In this embodiment, the full-color copying machine according to the first embodiment shown in FIG. 4 is used, and its explanation will be omitted.

Next, the image forming process in this embodiment will be explained.

First, as shown in FIG. 13(a), the photoreceptor drum 1 is exposed with a positive corona while being uniformly exposed to light of wavelength λ and light of wavelength λ2 by the negative charger 2a (see FIG. 4). Perform primary charging. As a result, only the L layer is charged (charged) to +1500V, and the surface potential of the photosensitive drum 1 is also +15.
00V (see point a in Figure 14).

Next, as shown in FIG. 13(b), the photoreceptor drum is secondary charged with a negative corona while being uniformly exposed to light of wavelength λ1 by the secondary charger 2b (see FIG. 4). The charge density of the negative corona at this time is set to 4/3 of the positive corona in the primary charging, so that the MM is negatively charged and the surface potential of the photoreceptor drum 1 is set to -2500V (see the point in Figure 15). .

Furthermore, tertiary charging is performed in the dark using the positive corona of the tertiary charger 2c (see FIG. 4). The charge density of the positive corona at this time is set to 273 for the positive corona in primary charging, and the U layer is thereby negatively charged. As a result, layer 1 is charged (charged) to +500V, and layer M is charged to +500V.
000V, the U layer is charged (charged) to +100OV, and the surface potential of the photosensitive drum l is set to +500V (see point C in Figure 15).
.

At this time, +500v of one layer is for forming a yellow electrostatic latent material, and +500v of +500v of one layer of 1M layer is for forming a yellow electrostatic latent material.
V is for magenta electrostatic latent image formation, and the remaining 500V
is for forming a yellow electrostatic latent image. Further, the negative yellow electrostatic latent image of the M layer is the same as that of the first layer for forming the positive yellow electrostatic latent image, and has the role of not allowing it to surface until the end of the process.

Similarly, +500V out of +100OV for the c layer is for forming a cyan electrostatic latent image, and the remaining +500V is for forming a positive magenta electrostatic latent image to neutralize the negative magenta electrostatic latent image for the M layer.

When the photosensitive drum 1 is brought into such a charged state, λ
0. λ2. Light images corresponding to three colors, cyan, magenta, and yellow, are simultaneously exposed and written using laser light having three wavelengths of λ.

That is, the light of wavelength λ carries yellow image information, the light of wavelength λ2 carries yellow image information and magenta image information, and the light of wavelength λ□
The light carries magenta image information and cyan image information.

During this exposure writing, in the first embodiment described above, the pixels to which toner is not attached are exposed, but in this embodiment, the pixels to which toner is attached are exposed. . For example, regarding a pixel to be black, in the first example JIi, λ8. λ2. The laser beams of three types of wavelengths λ, .
λ2. Laser beams of three different wavelengths, λ, are both turned on.

The charge distribution after such exposure is shown in FIG. 14(a). As shown in this figure, black
) +Cyan, Green
The pixels corresponding to each color of blue and blue are set to the surface potential of Ov (see point d in Figure 15), and the pixels of magenta and yellow are set to the surface potential of Ov.
), red, and white pixels are set to a surface potential of +500V (see point d' in FIG. 15). Note that in the 14th @ pixel corresponding to white color is omitted.

First, as shown in FIG. 14 (,), reversal development by the positively charged cyan toner is
This is carried out under a bias voltage of 0 V, and cyan toner is deposited on pixels corresponding to each color of black, cyan, green, and blue as indicated by black circles.

Next, as shown in FIG. 14(b), the wavelength λ,
After uniform exposure with light (780 nm), development with magenta toner is performed. Since more than 90% of the light with wavelength λ passes through the cyan toner already attached, only the positively charged portion of the U layer is selectively attenuated, resulting in a charge distribution as shown in Figure 14(b). becomes. That is, the positive magenta electrostatic latent image in the U layer disappears, and the negative magenta electrostatic latent image appears in the M layer, resulting in black and magenta.
genta) Red and Blue
) are set to the surface potential of Ov (see point e in Figure 15), and the pixels corresponding to the other colors, cyan (Cyan
), Green and Yellow
The pixels corresponding to each color (low) are made to have a surface potential of -500V (see point e' in Figure 5).

In this state, reversal development is performed using negatively charged magenta toner, and as shown by the gray circles in FIG.
a) Magenta toner is applied to pixels corresponding to each color of red (Red) and blue (Blue).

Furthermore, as shown in FIG. 14(c), the wavelength λ2
After uniform exposure with light (680 nm), development with yellow toner is performed. Since the already attached magenta toner also transmits light of wavelength λ2 well, only the negatively charged portion of the M layer is selectively attenuated, resulting in a charge distribution as shown in FIG. 14(c). Become. That is, the positive yellow electrostatic latent image in the MM disappears and the negative yellow electrostatic latent image appears in the L layer, resulting in black, yellow,
Pixels corresponding to each color of red (Red) and green (Green) are set to a surface potential of oV (first
(See point f' in Figure 5)・Other magenta (Magenta)
, Blue.

The pixels corresponding to each color of cyan and white are set to a surface potential of +5oov (I5
(See point f in the figure).

In this state, reversal development is performed using the positively charged yellow toner, and as shown by the white circles in FIG. 14(c), black and yellow C1- (Yel
low), Red (Red) and Green (Gr
Yellow toner is attached to pixels corresponding to each color (e.e.n). As a result, a full-color toner visible image is formed on the photoreceptor drum 1.

Note that during such development, development with magenta toner and development with yellow toner are preferably performed by so-called non-contact development.

The full-color toner visible image formed on the photoreceptor drum 1 is transferred to the recording paper side by the transfer charger 11 (see FIG. 4), but before that, the toner is transferred by the pre-transfer charger 9. Pole Ij, t14 adjustment is performed. That is, after development, the cyan toner and yellow toner are positively charged, and the magenta toner is negatively charged, and the pre-transfer charger 9 unifies the toner polarity to one side, positive or negative. It looks like this. Transfer charger 11
The transfer action is the same as normal corona transfer, and the transferred image is fixed on the recording paper by thermal fixation.

In the full-color image obtained in this way, in addition to being able to obtain a good full-color image without any positional deviation, as in each of the above embodiments, the reproducibility of edots in particular is improved in terms of image density. As a result, the gradation reproducibility of highlighted areas has been improved.

This fourth embodiment uses the apparatus in the above-mentioned embodiment, but the above-mentioned second and third embodiments are improved by inserting bias light data that reduces the charge of the L layer by half at the exposure point of λ. This can be similarly applied to the apparatus in the embodiment.

(Effect of the invention) As described above, according to the invention described in the claims and claim 2, each photoconductive layer of a composite photoreceptor formed by laminating three photoconductive layers , electrostatic latent images corresponding to each color and these corresponding to each color! A neutralizing electrostatic latent image of different polarity and the same shape is formed to prevent the pm latent image from temporarily coming to the surface, and a full-color image can be satisfactorily formed with a simple structure and only one image forming process. High-speed, high-quality images can be formed using a small, low-cost device, and the device can be easily implemented.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (c) are side explanatory views explaining the charging process of the photoreceptor in the first embodiment of the present invention, and FIGS. 2(a), (b), and (c) are FIG. 3 is a diagram showing surface potential fluctuations of the photoreceptor in the first embodiment of the present invention. FIG. 4 is a diagram showing the surface potential fluctuation of the photoreceptor in the first embodiment of the present invention. FIGS. 5(a), 5(b), and 5(c) are explanatory side views showing a full-color copying machine as an example of an image forming apparatus for implementing the process of charging a photoreceptor in a second embodiment of the present invention. 6th side explanatory diagram explaining
Figures (a), (b), and (C) are side explanatory views explaining the developing process of the photoreceptor in the second embodiment of the present invention, and Fig. 7 is the surface potential of the photoreceptor in the second embodiment of the present invention. FIG. 8 is a diagram showing fluctuations, and FIG. 8 is a side explanatory view showing a full-color copying machine as an example of an image forming apparatus for carrying out the present invention. FIGS. 9(a), (b), and (C) ) is a side explanatory view illustrating the charging process of the photoreceptor in the third embodiment of the present invention,
10(a), (b), and (c) are side explanatory views illustrating the developing process of the photoreceptor in the second embodiment of the present invention;
FIG. 1 is a diagram showing surface potential fluctuations of a photoreceptor in a third embodiment of the present invention, and FIG. 12 shows a full-color copying machine as yet another example of an image forming apparatus for carrying out the present invention. Side explanatory view, Fig. 13 (a), (b), (c
14A and 14B are explanatory side views illustrating the charging process of the photoreceptor in the fourth embodiment of the present invention. (C) is a side explanatory view illustrating the developing process of the photoreceptor in the fourth embodiment of the present invention, and FIG. 15 is a diagram showing surface potential fluctuations of the photoreceptor in the fourth embodiment of the present invention. L, 21. /! l...Photoconductor tram, 2,22゜42.
...Charger, 4,24.44...Cyan developing device. 6.24.44...Magenta developing device, 8,28°48
...Yellow developing device.

Claims (1)

[Claims] 1. After uniformly charging the photoconductive layer of the photoreceptor to a predetermined potential, image information for each color is written by exposure to form an electrostatic latent image corresponding to each color image; In a full-color image forming method in which a full-color image is obtained by developing an electrostatic latent image corresponding to each color image with each color toner, a photoconductive layer is formed by laminating three photoconductive layers sensitive to light of different wavelengths. charging each photoconductive layer of the composite photoreceptor to a predetermined potential so that the photoconductive layers have alternating polarities in the stacking order while selectively and uniformly exposing each photoconductive layer to light of a predetermined wavelength in the dark; By simultaneously exposing image information corresponding to each color to each wavelength light corresponding to the photosensitivity of each photoconductive layer, an electrostatic latent image corresponding to each color and these images are formed on each of the three photoconductive layers. A process of forming neutralizing electrostatic latent images of different polarities and the same shape to temporarily prevent the electrostatic latent images corresponding to each color from appearing on the surface, and a process of selectively and uniformly exposing the electrostatic latent images of a predetermined wavelength to a composite photoreceptor. a step of developing by sequentially supplying each color toner corresponding to each color electrostatic latent image while making the potential distribution corresponding to each color electrostatic latent image visible on the surface portion of the image to obtain a full-color toner visible image; A full-color image forming method comprising: 2. In the full-color image forming method as set forth in claim 1, electrostatic latent images corresponding to each color and a neutralizing static image having the same shape and different polarity for temporarily preventing the electrostatic latent images corresponding to each color from coming to the surface. Negative image with toner attached to the light irradiated area
A full-color image forming method that uses positive reversal development for visualization.