JPH03209276A - Color recording method - Google Patents

Abstract

PURPOSE:To print black and two other colors with a device of a small size by forming a negative latent image with a first exposure, carrying out reversal developing at a first developing, carrying out positive exposure at a second exposure, and carrying out positive developing with more than two developing devices provided with toners of different colors from the first developing. CONSTITUTION:An electrostatic latent image carrier is divided into more than two parts and electrified to different electrification levels, the negative image is formed by carrying out the first exposure 4 on a photosensitive body 1, reverse developing is carried out on this by the first developing device 5, and the black first image is formed, for example. Next, a background range is positively exposed by the second exposure 6, but since the photosensitive body 1 is divided into more than two different potential levels formed by the electrification, potential levels of different images are formed. Therefore, by setting bias of more than two developing devices 7 and a provided with toners of different colors from the first developing device, two more different colors of toner can be further developed in the positive. Thus, function of more than two tones of black and another color can be obtained, the cost can be reduced, and the device can be made compact.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a color recording method using an electrophotographic recording method, and more specifically, the present invention relates to a color recording method using an electrophotographic recording method. , relates to a color recording method that reproduces three or more colors.

(Prior art) Information output devices such as computers use printers that use lasers, LEDs, or liquid crystals that apply copying technology, electrostatic printers, or electrostatic images that have ions attached to dielectric materials. This is called ionography.

Alternatively, a method called magnetography that utilizes a magnetic latent image is known. The center of these information outputs is
Previously, black and white images were the main focus, but as information processing becomes more sophisticated, the need for printers that add color has increased, and many proposals have been made for this purpose. (Category: ■ Repeating and rotating a latent image carrier such as a photoreceptor multiple times,
A method of developing a different color each time ■ A method of using multiple photoconductors and having each photoconductor share the development of a different color and transferring it to the same paper ■ A toner image developed on a transfer drum There is a method of transferring a plurality of transferred toners to paper at once. There is a method of forming two latent images of different levels on one photoreceptor and developing different colors on them.

These methods have the following problems.

In case (2), it is necessary to rotate the photoreceptor by the number of times for one color, which slows down printing time and causes color shift.

In method (2), the same paper transfers the toner images on these photoreceptors at different locations (therefore, there is a problem that the positional shift of those colors is likely to occur, and Since it is necessary to install many sub-processes in the process, the equipment becomes complicated, takes up a lot of space, and costs are high.

Furthermore, there is a problem that reliability is also lowered.

Method (2), like method (2), requires multiple rotations of the photoconductor depending on the number of colors, which slows down the printing speed. However, there is a problem in that the overall size of the device increases.

Method (2) reproduces multiple colors by one rotation of the photoconductor, and moreover, development is done in multiple colors on the photoconductor and transferred at the same time, so the above-mentioned problem of ■■■ is solved. As such, it has received particular attention. This method is called a one-bath two-color process, and it was first published in Japanese Patent Application Laid-Open No. 5
Publication No. 9-2056, Japanese Unexamined Patent Publication No. 59-38762,
JP-A-59-60445, JP-A-59-1243
No. 53, JP-A-59-124354.

JP-A-60-46565, JP-A-60-5055
No. 3, Japanese Patent Application Laid-open No. 59-58442.

JP-A-61-15'8340, etc. These had two-level latent images, one for negative-negative development, and the other for negative-positive development. However, these were limited to black and one other color. On the other hand, there is an increasing need for printers that can output black and two or more other colors. For example, there is a request for three colors (one color for format and two colors for text). The basic latent image formation and development method to meet this demand is, for example, disclosed in Japanese Patent Application Laid-Open No. 6050.
As described in Japanese Patent No. 553, it was necessary to repeat the exposure process for forming a latent image and the development process for visualizing this latent image as many times as necessary.

In this method, it is necessary to write three or more images, and the cost required for these devices and processing of electrical signals increases significantly, leaving the problem that 0 cannot be used for general purposes. Furthermore, when developing a third color, there is a problem in that potential control is difficult.

[The problem that the invention tries to solve! ! ! ] The present invention was made in order to solve these problems, and an object of the present invention is to provide a color recording method that is relatively small and can print black and two other colors, for example. It is.

[Means for Solving the Problems] In the color recording method of the present invention, the electrostatic latent image bearing member is divided into sections, charged so that at least two sections have different conditions, and in the first exposure, a negative latent image carrier is charged. By forming an image, performing reversal development in a first development, positive exposure in a second exposure, and positive development in two or more developing devices having toner of a different color from the first development. It is characterized by printing in three or more colors.

Of course, a plurality of regions may be divided and may include regions that are charged under the same conditions. Here, the electrostatic latent image carrier refers to a well-known photoreceptor such as a photoreceptor made of selenium, amorphous silicon, or an organic material. Any different areas of a charge carrier, such as a photoreceptor, can be charged under different conditions by using various types of discharges, such as bottle-like charging, flat plate type corona dischargers, and contact charging such as brushes, etc. means. The different conditions are the setting of charging conditions such that the photoreceptor can be divided into different potential levels, the insertion and removal of a shielding object, the electric field control that controls the flow of ions, the division of voltage application to the discharge generator, and furthermore, This includes all methods in which charging conditions are varied, such as a discharge device that selectively causes ions to flow out and adhere to the surface of a photoreceptor by controlling an electric field.

[Function] The color recording method of the present invention divides the electrostatic latent image carrier into two or more parts, charges them to different charge levels, and then forms a negative image by first exposing the photoreceptor to light. , this is reversely developed in the first development to form, for example, a black first image. Next, the background area is positively exposed in the second exposure, but since the photoreceptor is divided into two or more different potential levels formed by charging, the potential levels of different images are different. It is formed.

Therefore, by setting the bias of two or more developing devices having toner of a different color from the first development, it is possible to perform positive development of toner of two or more different colors.

This series of steps allows images of three or more colors to be developed with only one rotation of the photoreceptor.

[Example] FIG. 1 is a schematic configuration diagram of an apparatus used in an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the steps of latent image formation and visualization development process. In FIG. 1, 1 is a photoreceptor, 2 and 3 are chargers, 4 and 6 are exposure devices, 5, 7, and 8 are developing devices, and 10 is a transfer device.

Two chargers 2 and 3 installed on the photoreceptor l in Fig. 1
As a result, charges of different levels are formed on the photoreceptor 1 by dividing the top of the photoreceptor 1 into two sections as shown in FIG. 2A, for example.

This state is shown by (A) in FIG. 2, and a region 1 with a high charge density, that is, a high surface potential, and a region 1 with a lower surface potential are formed separately.

Next, as shown at 4 in FIG. 1, image information by a laser or the like is projected in the form of light, and the charge in that area is eliminated, and the Ia and Ila shown in (B) in FIG.
A latent image is formed.

This latent image is developed by a first developing device 5 with toner having the same polarity as the latent image. In this case, the developing bias of the developing roll is set to
By setting the level to the level indicated by the broken line in (C) of the figure, the latent images Ia and IIa are developed to approximately the same extent.

The toner of this first development 5 is usually black, but is not limited thereto. Next, as shown at 6 in FIG. 1, the image information is converted into an optical signal by the second exposure point.
A first image is projected onto the photoreceptor on which it is formed. The state of the latent image is at the level shown in FIG. 2(D). New electrostatic latent images are formed at different levels, such as Ib and nb. This is because the initial charge level of the photoreceptor is different, as shown in FIG. 2(B). (E) and (F) in FIG. 2 show the state in which the image is developed by the second developing device 7 and the third developing device 8, respectively, and (E) shows the state in which the image is developed by the second developing device 7. The developing bias is set at the level indicated by the broken line. (F) shows a state in which the image is developed by the third developing device 8.

In this case, the color developed by the third developing device 8 is the latent image Ib.
Since both nb and nb are developed, the result is a mixture of both colors. For example, if the second development is red and the third development is blue, in addition to black, black, which is reproduced as blue and purple, and two other colors will be reproduced. Since the multicolor toner images formed on the photoreceptor have charges of different polarities, they are charged by a corotron 9 or the like and aligned to the same polarity, and then the paper 13
The image is transferred onto the image using the transfer device 10. Thereafter, fixing of the toner onto a sheet of paper, cleaning of the photoreceptor, etc. are carried out by a cleaning pre-processor 11 and a cleaner 12, as used in ordinary copying machines and printers. In this way, the process shown in Figure 2 for one black and one color, which is the basic process, can be made with only a few changes such as changing the initial photoreceptor charge level. It is now possible to have the function of two colors,
We were able to bring about the great effect of using this function without sacrificing space, cost, or printing speed.

It will be understood that if three or more potential levels are set by charging and color development is performed accordingly, two or more colors, one black and two colors, can be printed.

FIG. 3 shows an example of the obtained record, where 14 is a black text area, 15 is a blue shaded area due to the third development, and 16 is an area where toner from the second and third development is overlapped. This is an example of purple shading.

One of the specific experimental conditions of the above-mentioned Examples will be explained below, but the present invention is not limited to these materials and set values. Photoconductor l uses a normal selenium photoconductor,
A drum type with a diameter of 200 mm was used. The charger 2 is a scorotron, and a voltage of 800 V is applied to the wire and grid of the scorotron as shown in FIG. 4(A). The axial length of the photoreceptor of the charger 3 is the same as that of the charger 2, but a portion of the opening of the discharger is covered with an insulator such as Mylar. In this way, the photoreceptor 1 is divided into a portion that is only charged by the charger 2 and a portion that is also charged by the charger 3. It is preferable to use a scorotron for the charger 3 to precisely control the photoreceptor potential, and the bias of the wire and grid is set so that the charger 3 brings the photoreceptor potential to 1100V. It is not only possible to use a scorotron using a wire (it is also possible to use a bottle-shaped charging device).

As shown in FIG. 5, the wires 19a and 19b are driven by a winding device 20 driven by a winding signal 21, and the shielding body that controls the charger 3 is connected to the shielding body 18.
, for example, a Mylar film 18 with a thickness of 100 microns.
enters and exits between the charger 3 and the photoreceptor l. This shield 1
8 does not need to be limited to Mylar, and may be an insulating material that is less likely to deteriorate due to ozone etc., such as ceramic film,
Mica, a metal surface coated with an insulator, plastic, etc. can be used.

As shown in FIG. 6, a fixed type charger 23, 24 divided into two may be used without using a shield. In addition to this method, as shown in FIG. 7(A), as a method for selectively controlling two charging levels, a scorotron grid 30 is used as a charger 3 and is stretched in the direction of movement of the photoreceptor. It is also possible to cross the grid and selectively apply a bias potential to this grid.

As an experimental example, as shown in FIG.
By dividing the photoreceptor into regions with a 300V level difference, the corresponding surface potential of the photoreceptor could be divided into regions in the initial state with a level difference of 300V.

The same idea can be applied to the scorotron 33 of FIG. 7(A) and the corotron 34 of FIG. All you have to do is do it. For example, under the condition that a voltage of 4KV is applied to the wire, by creating a region where 100V and -1000V are applied on the shield part, more ions will flow to the photoreceptor side in the region where 100OV is applied, and -[ 000V
It was possible to provide the photoreceptor with an initial potential that was approximately 300 V higher than the applied area. For exposures 4 and 6, a commonly used helium neon gas laser was used.

FIG. 8 illustrates another example of the charger, which uses an ion generator. Drive electrode 41 and $ control electrode 4
Ions are generated by the potential difference between the photoreceptor 3 and the photoreceptor 48, and the ions are transferred to the photoreceptor 48 by the screen electrode 45.

With such a device, it becomes possible to set divided regions more precisely. FIG. 9 is an explanatory diagram of this entire electrode arrangement.

Ions are generated only in the area where the drive electrode 41 and control electrode 43 interact, and the ions are emitted toward the photoreceptor through the hole in the drive electrode 41, and the charger 2 further increases the generated charge. I can do it. As a preferred implementation condition, stainless steel with a thickness of 30 microns was used for the drive electrode 41, control electrode 43, and screen electrode 45.

Alumina with a thickness of 50 microns was used for the insulating materials 42 and 44. A pulse signal having a low level potential of 600 V, a high level potential of 1000 V, and a pulse width of 10 microseconds was applied to the control electrode 43 from the ion control electrode 47. Further, an AC voltage of 2.5 KV peak-to-peak voltage and a frequency of 1.5 MHz from a high-voltage high-frequency power source 46 was applied to the drive electrode 41.

A voltage equivalent to the potential charged by the negative charger 2 is applied to the screen electrode 45 . Here, the screen electrode 4
The gap between 5 and the photoreceptor 48 was 200 microns.

Further, as a method for selectively attaching charges to the surface of the photoreceptor 48, it is also possible to use an ion flow control head disclosed in Japanese Patent Application Laid-open No. 138250/1983.

The present invention is not limited to the embodiments described above, and other elemental processes related to the present invention, such as those described below, may be used. For the first exposure 4 and the second exposure 6, in addition to the helium neon laser, a semiconductor laser or the like can be used depending on the sensitivity of the photoreceptor. Further, LED, liquid crystal, and fluorescent display tube type light input devices such as those disclosed in Japanese Patent Application Laid-open No. 169356/1986 can also be used. In the first exposure 4, as shown in FIG. 4(C), the image area was exposed and the surface potential was lowered to about 60V.

The first developing device 5 performs reversal development, that is, the exposed portion is developed.

Therefore, the toner is selected to be highly charged. As shown in the fourth factor (D), by applying 550 V as the developing bias m, the exposed area where the potential has been removed to 60 V is developed, and the area with a high surface potential is not developed.

Although the first developing device 5 can be used for either a normal two-component development method or a -component development method, an example in which a normal magnetic brush development method is used is shown here. '40m
A magnetic roll with a diameter of m is used, and the magnetic force in the development area is 1
The pressure was set to 200 Gauss, and the center part was set to 900 Gauss to increase the movement of the developer, thereby improving 2 development performance.

The carrier used was 80 micron ferrite. Of course, a carrier such as iron powder or a carrier in which magnetic powder is dispersed in a polymer can also be used.

The main parameters of the developing device are that the gap between the developer cutting plate and the developing roll is 0.4 mm, and the gap between the developing roll and the photoreceptor is 0.7 mm.

The center of the magnetic field lines of the magnet was set at an angle of +8 degrees with respect to the center of the photoreceptor, that is, directed upward.

The speed of the developing roll was set at twice the speed of the photoreceptor.

As for the development method, although ordinary magnetic brush development has been described here, it is also possible to use -component development or a two-component conductive magnetic brush. In the second developing device 7, a negatively charged yellow toner of 10 microns was used as a toner, and a type of carrier in which magnetic powder was dispersed in a polymer was used as a carrier. The gap between the developer cutting plate and the developing roll was 0.6 mm, the gap between the developing roll and the photoreceptor was 0.7 mm, and the angle of the center of the magnetic force of the magnet with respect to the horizontal line was +5 degrees. The speed of the developing roll was set at 1.5 times the speed of the photoreceptor. The configuration of the other developing devices is the same as that of the first developing device. The developing method of the second developing device 7 and the third developing device 8 is preferable because a material that forms magnetically soft spikes, as used here, does not disturb the toner in the first development.

From this point of view, a method using non-contact development is also suitable. The third developer is the same as the second developer except that cyan toner is used. The second and third developing units.

As shown in FIGS. 4E and 4F, each image is normally developed by applying development biases of 700V and 460V, respectively. That is, the charged areas are developed. In this manner, the black, cyan, and green prints formed are formed during one photoreceptor rotation cycle. The toner images on these photoreceptors are decapolar for black, and negatively charged for yellow and cyan, so
In order to collectively transfer these to paper, the toner on the photoreceptor is irradiated with a corona. This is represented as a transfer pretreatment indicated by 9 in FIG. When the photoreceptor is made of selenium, positive charges are easily removed, so it is desirable that all toner be converted by a positive corona. Suitable transfer conditions were as follows: the voltage applied to the wire was +4 KV, the gap between the corotron shield and the photoreceptor was 3 mm, and the gap between the corotron wire and the photoreceptor was 6 znm.

In this way, the polarity-converted toner is transferred onto the paper by the negative corona. The toner on the paper is fixed by a stationary device (not shown), and the untransferred toner remaining on the photoreceptor 1 is cleaned after being neutralized, and the next cycle is repeated.

In the above example, selenium was used as the photoreceptor 1, but of course it is also possible to use an organic semiconductor, and the polarity of the toner and the optimal image writing device can be selected based on this. Further, the photoreceptor 1 can be used not only in a drum shape but also in a belt shape, and furthermore, the technical idea of the present invention is to selectively form ions not only on the photoreceptor but also on the current reader. This technology can also be applied to ion jet printing, electrostatic printing, etc.

(Effects of the Invention) The present invention can produce two colors by simply adding a second charging device without imposing any major restrictions on a printer that has a basic configuration of only black and one other color. It is possible to obtain the above functions, and it is possible to perform compact color recording at high speed at extremely low cost. If black is not used, three colors can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used in an embodiment of the present invention;
Fig. 2 is an explanatory diagram of the relationship between the potential on the photoreceptor and development where multicolors are reproduced, Fig. 3 is an explanatory diagram of an example of printing, and Fig. 4 is
61 is a photoconductor, 2.3 is a charger, and 4.6 is an explanatory diagram of the relationship between the potential of a photoreceptor and a developing bias. FIGS. 5 to 9 are explanatory diagrams for obtaining divided charging potentials. Exposure, 5.
7.8 is a developing device,

Claims (1)

[Claims] The electrostatic latent image bearing member is divided and charged so that at least two colors are under different conditions, a negative latent image is formed in the first exposure, this is reversely developed in the first development, and a negative latent image is formed in the first development. By performing positive exposure with two exposures and performing positive development with two or more developing devices having toner of a different color from the first development, 3.
A color recording method characterized by printing more than one color