JPH0428306B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a multicolor electronic recording method in a multicolor electronic recording device using an electrophotographic recording method, an electrostatic recording method, etc. The present invention relates to a method that enables clear recording without any blemishes.

(b) Background of the Technology With the diversification of information in recent years, there has been a demand for multicolor electronic recording devices capable of recording information in two or more colors, and various devices and recording methods have been proposed.

(c) Prior art and problems Figure 1 is a schematic diagram for explaining a multicolor electronic recording device.To simplify the explanation of the prior art, we will explain the recording method using a two-color electrophotographic recording device. explain. FIGS. 2 to 7 show the photoreceptor in each step of forming a two-color toner image on a latent image forming medium (hereinafter referred to as photoreceptor) using the two-color electrophotographic recording apparatus shown in FIG. FIG. 3 is a diagram showing the above potential state.

As shown in these schematic diagrams and potential state diagrams, in the conventional two-color electrophotographic recording device, a photoconductive layer 2 such as selenium (Se) is laminated on a photoreceptor 1 on a conductive layer. , the initial charger 3 such as a charging corotron is used to uniformly charge the battery to a potential Vs as shown in FIG. Next, negative exposure corresponding to the first color information is performed on the photoreceptor 1 by a first exposure means 4 made of, for example, an OFT (Optical Fiber Tube), so that the potential of the exposed portion becomes as shown in FIG. A latent image 21 corresponding to the first color information attenuated to approximately OV is formed. Next, the latent image 21 is transferred to a first developing unit 5 of a two-component magnetic brush developing method using, for example, a two-component developer containing positively charged red toner.
Then, as shown in FIG. 4, an appropriate developing bias voltage VB ₁ is applied by the first developing bias voltage applying device 6 so as not to cause fogging in the background area, and development is performed to form a toner image 22 of the first color. form. At this time, the potential on the first color toner image 22 is _Vt1 . Next, before the second exposure means 8 performs negative exposure corresponding to the second color information, the body electric charge of the photoreceptor 1 is charged by the recharging device 7, which is a corotron with grid control, as shown in FIG. The potential Vs is recharged to a potential Vs ₁ at which a latent image strength necessary to obtain a sufficient toner image density in the second development using a one-component magnetic toner development method to be described later. At this time, by setting the grid voltage of the recharging device 7 to Vs ₁ , the potential Vt ₁ on the first color toner image 22 also becomes the same potential as the recharging potential Vs ₁ of the photoreceptor 1. Thereafter, the second exposure means 8 performs negative exposure corresponding to the second color information on the photoreceptor 1, and the potential of the exposed portion is reduced to approximately OV as shown in FIG. A latent image 23 corresponding to color information is formed, and subsequently, as shown in _FIG . A developing bias voltage VB ₂ is applied, and development is performed by a second developing device 9 using a one-component magnetic toner developer (black) to form a toner image 24 of a second color. The red and black toner images 22 formed on the photoreceptor 1 in this way,
24 is transferred onto the recording paper 12 by the transfer device 11, and fixed by thermocompression bonding or the like in a fixing section (not shown). On the other hand, the toner remaining on the photoreceptor 1 is neutralized by a static eliminator 13 and cleaned and removed by a cleaner 14. Furthermore, all charges on the surface of the photoreceptor 1 are removed by an optical charge eliminator 15, and a new recording cycle begins.

In the above recording method, the charging potential Vs of the photoreceptor 1 and the potential Vt 1 on the first color toner image (red toner image) 22 are changed to the charging potential Vs ₁ by recharging _.
The reason for this is that during development to form the second color toner image (black toner image) 24, the developer of the second color adheres to the first color toner image 22 that has already been formed. This is to prevent color mixture from occurring. Incidentally, when the recharging process is omitted in the above recording method, the first image formed by applying a predetermined developing bias voltage VB ₁ to the latent image 21 portion corresponding to the first color information, as shown in FIG. There is a potential difference between the potential Vt ₁ on the color toner image 22 and the charging potential Vs of the photoreceptor 1. In this state where there is a potential difference, negative exposure corresponding to the second color information is performed on the photoreceptor 1 as shown in FIG. 9, and the potential of the exposed portion is reduced to approximately OV to obtain the second color information. Then, a predetermined developing bias voltage VB ₂ is applied to the latent image 23, and a second color toner image 24 is formed by second development using a one-component magnetic toner (black). is formed, the potential difference (VB ₂ −
Vt ₁ ), the developer 24a of the second developer adheres to the already formed toner image 22 of the first color, resulting in color mixing.

Therefore, in the conventional two-color recording method described above, color mixing is prevented by the recharging process described above, and good two-color recording is made possible.

However, in the above-mentioned conventional two-color electrophotographic recording method, there are cases where the latent image strength required to obtain a toner information image with good color density is large, and when the first development and the second development are performed separately. If the difference in required latent image strength is large, the potential Vt ₁ on the first color toner image 22 and the charged potential Vs of the photoreceptor 1 may not be equal even after recharging. The first image that has already been formed during the second development process is
There was a drawback that color mixing occurred in the toner image 22 of the colors, and a good two-color toner image could not be obtained.
Incidentally, according to studies by the present inventors, this phenomenon of defects becomes noticeable when the electrostatic capacitance Cp of the photoreceptor is large. Ultimately, these problems are caused by an increase in the amount of charge required to obtain a predetermined charging potential.

ρ: Volume charge density of toner layer (image), dt: Thickness of toner layer (image), ε _p : Permittivity of vacuum, εr _l : Average relative permittivity of toner layer (image), Cp: Photoreceptor When capacitance, g: charge density on the photoreceptor, the potential Vt ₁ on the first color toner image 22 is given by the following equation. That is, Vt ₁ = 1/2(ρdt ₂ /ε _p εr _l )+ρdt/Cp+g/Cp In the above equation, the first term expressed as 1/2(ρdt/ε _p εr _l ) is the toner layer (image ) own potential,
The second term represented by ρdt/Cp is the potential of the photoreceptor due to toner charge, and the third term represented by g/Cp is the potential of the photoreceptor due to surface charge.

Then, for a given amount of potential charging, the capacitance Cp
If a photoreceptor with a large
ie, the voltage applied to the toner layer (image) increases. If the voltage becomes too large, the toner layer (image)
It was discovered that aerial discharge began to occur between the surface area and the photoconductor surface, and that this made it difficult to raise and equalize the potential of the toner layer (image) to the potential of the photoconductor. There is. Regarding the two-color electrophotographic recording device shown in FIG. 1, the first development involves two-component magnetic brush development (necessary latent image strength of 300 to 400 V or more);
One-component magnetic toner development (required latent image strength) for second development
700 to 800 V or more), but in this case, if the photoreceptor capacitance Cp exceeds approximately 1 μF/m ² , a problem of potential non-uniformity after recharging occurs. Note that the value of the capacitance Cp of the photoconductor where potential non-uniformity occurs after recharging is not an absolute value, but depends on the dielectric constant ε of the toner used.
It also changes depending on.

(d) Purpose of the Invention In view of the above-mentioned conventional drawbacks of the present invention, it is possible to use a toner image of the first color that has already been formed, regardless of the difference in capacitance, etc. of the photoreceptor that forms the multicolor toner image. The potential Vt ₁ and the charging potential Vs of the photoreceptor are
It is an object of the present invention to provide a new multicolor electronic recording method that can easily adjust the potential to obtain a sufficient toner image density in the next development and that can obtain good multicolor recording without color mixture. It is.

(e) Structure of the Invention According to the present invention, this object is to erase the charge in a portion corresponding to color information on a latent image forming medium that has been initially charged, using a latent image forming means such as light irradiation or electric discharge. to form a latent image, and after converting the latent image into an image by a developing means, recharging the surface of the latent image forming medium on which the toner image has been formed; a process of forming a latent image by erasing the charge in a portion corresponding to the next color information using a latent image forming means using next light irradiation or electric discharge; and a process of converting the latent image into a toner image by a developing means. In an electronic recording method in which multicolor information is recorded by sequentially repeating the above-mentioned initial charging potential, the latent image strength required for the development step in which the latent image strength is maximized among the development steps performed by sequentially repeating the above-mentioned initial charging potential can be obtained. At least one of the latent image forming means forms a latent image on the initially charged latent image forming medium. By providing a multicolor electronic recording method characterized in that a latent image is formed by removing only a part of the electrical charge held by an image forming medium without removing all of it. achieved.

(f) Embodiments of the invention Examples of the invention will be described in detail below with reference to the drawings.

FIGS. 10 to 15 show potential states on the photoreceptor during each recording process when an embodiment of the multicolor electronic recording method according to the present invention is applied to the two-color electrophotographic recording apparatus shown in FIG. 1. FIG.

An embodiment of the present invention will be explained using the configuration diagram of a two-color electrophotographic recording apparatus shown in FIG. It is uniformly charged to a potential Vs that provides the latent image strength necessary for one-component magnetic toner development, which is the final development. FIG. 16 shows the recharging characteristics of the recording apparatus of this example. This means that the potential difference between the potential on the first color toner image before recharging and the potential on the photoconductor 1 in the background area is 300V.
This is the case. When recharging is performed such that the potential change on the photoconductor in the background area exceeds 100V, the potential on the first color toner image changes to the photoconductor 1 in the background area.
It can be seen that the potential is no longer aligned with the potential above. For this reason, the initial charging potential is set in advance so that when the potential on the photoreceptor 1 is increased by recharging, the increase in potential will be 100 V or less until the potential at which the latent image strength required for one-component magnetic toner development is obtained. is set to a potential Vs that provides the latent image strength necessary for one-component magnetic toner development.

Next, for example, OFT (Optical
The first exposure means 4 consisting of Fiber Tube)
By controlling the exposure amount and performing negative exposure corresponding to the first color information, the potential of the exposed portion is determined to be a potential Vk at which the latent image strength necessary for the first development described below is obtained, as shown in FIG. A part of the charge on the photoreceptor 1 is removed so that a latent image 2 corresponding to the first color information is formed.
form 1. Next, the latent image 21 is developed, for example, by a first developer 5 of a magnetic brush development method using a two-component developer containing positively charged red toner and a first development bias voltage applicator 6, as shown in FIG. Apply an appropriate developing bias potential VB ₁ so as not to cause fogging in the background area, and perform development.
A toner image 22 of color is formed. Next, recharging is performed by a recharging device 7 consisting of a corotron with grid control. Since the potential on the photoreceptor 1 before recharging is the potential Vs at which the latent image strength necessary for one-component magnetic toner development is obtained, there is no need to increase the potential of this portion by recharging. Therefore, the first
From the results shown in Figure 6, the first
The potential Vt ₁ on the toner image 22 of the color can be made equal to the electrical voltage Vs.

Thereafter, the second exposure means 8 performs negative exposure on the photoreceptor 1 corresponding to the second color information, and the potential of the exposed portion becomes approximately OV as shown in FIG.
A latent image 23 is formed corresponding to the second color information that has been lowered to 100. Subsequently, as shown in FIG. development bias voltage equivalent to
By applying VB ₂ and performing development using the second developer 9 using one-component magnetic toner (black) to form the toner image 24 of the second color, the photoreceptor 1
Two-color (red, black) toner image 22 with no color mixture on top,
24 is obtained. Therefore, as in the conventional case, the first and second color toner images 2 formed on the photoreceptor 1
2 and 24 onto the recording paper 10 in the transfer section 8 and fixed by thermocompression bonding or the like in the fixing section 9, it becomes possible to clearly record two-color information without color mixture.

The above explanation has been made according to FIGS. 1 and 10 to 16, but in reality, each potential condition is adjusted in consideration of dark decay of the potential on the photoreceptor 1, leakage voltage during development, etc. Must be set. The specific potential conditions in this example are as follows. The electrostatic capacitance Cp of the photoreceptor 1 is 1.3 μF/m ² . The initial charging potential Vs is set to a value of about 1000 V, which is higher than the potential 800 V at which the latent image strength necessary for one-component development is obtained, taking into consideration dark decay, leakage voltage during development, and the like.
The potential Vk after the first exposure is about 400V, and the first development bias voltage _VB1 is set to 800V to perform development.
At this time, the potential on the photoreceptor 1 is attenuated to approximately 800V due to leakage voltage during development. When the potential conditions were set in this manner, the potential on the first color toner image could be raised to 800 V by recharging, and a good two-color image without color mixture etc. was obtained.
In the above embodiment, in order to simplify the explanation, two
Although an example of a color electrophotographic recording method has been described, the present invention is not limited to this example, and it goes without saying that it is applicable to a recording method of a multicolor electronic recording device that uses three or more colors. The same effect can be obtained. Furthermore, the present invention is not limited to multicolor recording using the electrophotographic recording method as explained in the above embodiments, but can also be applied to multicolor recording using an electrostatic recording method using a latent image forming means such as a pin electrode. Needless to say, it is applicable.

(g) Effects of the Invention As is clear from the above explanation, according to the multicolor electronic recording method of the present invention, the initial charging potential for the photoreceptor can be set such that the required latent image strength is the highest among the developing means. By setting the developing means to a potential that provides the necessary latent image strength or a potential higher than that, and reducing the amount of recharging in the recharging process, regardless of the difference in the capacitance of the photoreceptor, it is possible to The potential of the toner image being formed can be easily made to the same potential level as the charged potential of the photoreceptor.
As a result, it has the advantage that good multicolor recording without color mixture can be obtained, which is extremely advantageous in practice. Therefore, excellent effects can be achieved when applied to this type of electrophotographic recording system or electrostatic recording system multicolor electronic recording apparatus.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining a multicolor electronic recording device using a two-color electronic recording device of an electrophotographic recording method, and FIGS. Latent image forming medium (hereinafter referred to as photoreceptor)
FIGS. 10 to 15 are diagrams illustrating potential states when forming a two-color toner image, and FIGS.
Fig. 16 is a diagram of the state of potential on the photoreceptor in each recording process when applied to a color electrophotographic recording device, and shows the potential changes on the photoreceptor during recharging, the potential on the photoreceptor after recharging, and the toner image. FIG. 3 is a diagram showing the relationship between the potential of In the drawing, 21 is a latent image corresponding to the first color information, 22 is a toner image of the first color, 23 is a latent image corresponding to the second color information, 24 is a toner image of the second color, Vs is the initial charging potential of the photoreceptor, VB ₁ and VB ₂ are the developing bias voltages, Vk is the exposed area potential after the first exposure to obtain the necessary latent image strength in the first development,
Vt ₁ indicates the potential on the first color toner image 22.

Claims (1)

[Scope of Claims] 1. On a latent image forming medium that has been initially charged, a latent image is formed by erasing the charge in a portion corresponding to color information by a latent image forming means, and the latent image is transferred to a toner by a developing means. After the toner image is formed, the surface of the latent image forming medium on which the toner image has been formed is recharged, and the next latent image forming means corresponds to the next color information on the recharged latent image forming medium. In an electronic recording method in which multicolor information is recorded by sequentially repeating the process of erasing the charge of a portion to form a latent image and the process of converting the latent image into a toner image by a developing means, the initial charging potential is A latent image forming medium that is set at a potential equal to or higher than the potential that provides the latent image strength necessary for the development step in which the latent image strength is maximized in the sequentially repeated development steps, and that is subjected to the initial charging. Among the respective latent image forming means that form a latent image on the latent image forming medium, at least one of the latent image forming means removes only a part of the electrical charge held by the latent image forming medium without removing all of it. A multicolor electronic recording method characterized in that a latent image is formed using a multicolor electronic recording method. 2. The latent image forming means is a light irradiation means, and the latent image is formed by removing only a part of the electrical charges on the latent image forming medium by controlling the light energy. A multicolor electronic recording method according to claim 1. 3. The latent image forming means is a discharging means, and by controlling the amount of ions or electrons generated by discharge, only a part of the electrical charge on the latent image forming medium is removed to form a latent image. A multicolor electronic recording method according to claim 1, characterized in that: