JPS6318750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative/positive electrophotographic recording method that can be effectively used when recording format information and character information on paper.

To print (record) information using electronic photography,
There are two methods: the positive-positive method (usually used in copying machines) in which the information is exposed to positive light and then developed in reverse, and the negative-positive method (usually used in optical printers) in which the information is exposed to negative light and then developed in reverse. . The positive-positive method is the first
As shown in the figure, (1) first, the surface of the photoreceptor 4 is uniformly charged by the charger 2; At this time, if the photoreceptor is p-type, it is charged positively, and if it is n-type, it is charged negatively, but in this example, since the photoreceptor is p-type, the negative side of the power supply 3 is connected to the base 6, and the same charge is applied. A charger 2 connected to the positive side charges the surface of the photoreceptor 4 with a positive charge.
Next, (2) when the positive film 8 is placed on the photoreceptor 4 and irradiated with light P to perform positive exposure, the positive image 8a absorbs the light P and does not irradiate the photoreceptor 4, so that the positive charge is Although the charges are not removed, the charges are removed by being irradiated with light in areas other than the positive image 8a. Next, (3) sequential development is performed with toner 10 having negative polarity, and the toner 10 is attached to the positive exposed area (charge remaining area). If you want to record on photosensitive paper, you can simply heat and fix it, but if you want to record on plain paper, you need to follow the next step (4).
As shown in FIG. 2, plain paper 12 is placed on photoreceptor 4 and positively charged by charger 2. As shown in FIG. As a result, the toner 10 with negative polarity adhering to the positive exposure area is attracted to the plain paper 12 and transferred. Next, (5) the transferred toner image 14 on the plain paper is fixed by heat h.

As shown in FIG. 2, in the negative-positive method, first (1) the surface of the photoreceptor 4 is positively charged in the same manner as in the above-mentioned positive-positive method, and then (2) a negative film 14 is placed on the photoreceptor. Negative exposure is performed by irradiating the exposure light P. At this time, since the negative image 14a passes the light P, the charge is removed from that part of the photoreceptor, and the other parts are not irradiated with the light P, so that the positive charges remain. Next, (3) reversal development is performed using toner 16 having positive polarity. At this time, the charge remaining portion is at a positive potential and the static eliminating portion is at a zero potential, but it appears to be in a state similar to a negative potential, and the toner 16 adheres to it while being trapped by the lines of electric force that enter the portion. In the case of recording on photosensitive paper, it is sufficient to heat and fix it, and in the case of transfer to plain paper, next, as shown in step (4), plain paper 12 is placed on the photoreceptor 4 and charged negatively by the charger 2. Then, the toner 16 with positive polarity adhering to the negative exposure area is attracted and transferred onto the plain paper 12. Next, (5) the transferred toner image 14 on the plain paper is fixed by heat h.

By the way, documents generally consist of a format and the characters written on it. In order to print (record) such a document, it is necessary to record two types: the format and the character group. Additionally, it is generally easier to see if the format and text are in different colors, which is why it is preferred. Various methods have been considered for recording such formats and characters, one of which is the preprint method, which prints the format on paper in advance and records the characters on the paper. This preprint method allows multicolor printing, but it requires storing multiple types of preprint paper on which various formats are printed in advance, and then taking it out and recording the text information using electrophotography. It is troublesome in that it is necessary to prepare preprinted paper and to replace the paper every time the format changes. Therefore, methods of printing format information together with character information have been considered, including film overlay methods, electronic overlay methods, and the like.

In the film overlay method, format information is held in the form of a negative film, light is projected onto a photoreceptor through the negative film, and the photoreceptor is scanned with light modulated in accordance with character information, and both are overlapped and exposed. This method has the advantage of requiring fewer types of paper to be stocked (any type necessary for the paper size, such as A ₃ or B ₅ ), and eliminating the need to change paper as long as the paper size is the same. However, it is inconvenient because the format information needs to be in the form of a negative film, the film must be replaced every time the format changes, and multicolor printing is not possible.

Next is the electronic overlay method, which electrically combines format information and character information and records them simultaneously. With this method, both negative and positive exposures are possible, and if the paper size is the same, there is no need to change the paper or film even if the format information is different, making it very convenient for work. However, the hole length, or resolution, of the format information In order to reproduce pattern details by increasing the memory capacity, the memory capacity must be increased, which increases the electrical burden. Also, this method does not allow multicolor printing. In addition to the above method, there is also a method using two developing units and two photoreceptors.
It is also possible to rotate the paper and print the format in one process and the text in two processes.This method also allows two-color printing, but it requires two processes to print on one sheet of paper, and printing Slow speed. Recently announced color copiers are similar to this, with cyan,
It uses three toner colors, magenta and yellow (sometimes containing black toner), and can perform color printing by repeating the charging, exposure, development, and transfer steps three times, but it takes a long time to copy. There are some drawbacks.

The present invention has been made in view of the above points, and it is possible to integrate and combine character information of a negative image and format information of a positive image in one process, print on the same surface, and also perform multicolor printing. , is characterized by uniformly charging the surface of the photoreceptor, then projecting a negative image, performing reversal development on the charge-eliminating portion of the surface of the photoreceptor onto which light is projected, and then projecting a positive image. A process of removing static electricity from the residual charge area on the surface of the photoreceptor other than the positive image projection area, and performing forward development on the residual charge area of the positive projection area to form two types of toner images, negative and positive, on the same surface. It lies in having. Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 3A shows an example of an apparatus for carrying out the present invention, and FIGS. 3B and 3C show examples of negative and positive images used in the present invention. 18 is a drum-shaped photoreceptor, 2
0 is a charger such as a corotron, 22 is a reversal developer, 24 is a forward developer, 26 is a charger similar to 20, 28 is a transfer device, 30 is plain paper, 34 is a static eliminator, and 36 is a cleaning device such as a fur brush. It is a vessel. Reference numeral 21 indicates a negative exposure section consisting of a light source such as a laser light source and its modulation and deflection control system, and 23 indicates a positive exposure section consisting of a system similar to the optical system of a copying machine.

To explain the operation of this device with reference to FIG. 4, first, the surface of the photoreceptor 18 rotating in the direction indicated by the mark a is uniformly charged (positively charged in this example) by the charger 20. 4 Set the state as shown in Figure 1. Next, a negative image (which becomes character information) having a pattern as shown in FIG. 3B is projected, and the positive charge on the illuminated part, that is, the image F part is eliminated as shown in FIG. 42. Next, a toner having a positive polarity is sprinkled by the first developing device 22, and reversal development is performed as shown in FIG. 4. Next, a positive image with a pattern as shown in Figure 3C (this becomes format information) is projected, and Figure 4
The charge on the light irradiation part is removed as shown in . Next, a toner having a negative polarity is sprinkled on the second developing device 24 to perform sequential development as shown in FIG. 4.
Next, the charger 26 charges the toner of both positive and negative polarity adhering to the photoreceptor to either polarity (positive polarity in this example) or eliminates the charge with an AC voltage, and the charger 28 removes the charge. The back side of the plain paper 30 traveling in the direction of arrow b is charged with the opposite polarity, and the toner image (character information and format information) adhering to the photoreceptor 18 is transferred to the plain paper 30. Thereafter, the toner image transferred onto the plain paper is fixed by heating by the fixing device 32. Residual charge on the surface of the photoreceptor is removed by a static eliminator 34, and residual toner on the surface of the photoreceptor is removed by a cleaner 36 to bring the photoreceptor to an initial state. One step is completed as described above, and is repeated thereafter.

FIG. 5 shows the development performed in this process. Figure 5 1 shows the initial state where the photoreceptor surface is uniformly positively charged, 2 shows the state where the negative image is exposed and the charge on the light irradiated area is removed, and 3 shows the state where the negative image is reversely developed with toner having positive polarity and the negative image is removed. 4 shows a state in which toner is attached to the exposed area, 4 shows a state in which a positive image is exposed and the charge on the light irradiated part is removed, 5 shows a state in which positive image sequential development is performed, and 6 shows a positive and negative electrode for transfer. This shows a state in which both positive polarity toner images are made into positive polarity toner images.
Note that by color-coding the toner used in the first development and the toner used in the second development, two-color printing with different colors for the character image and the format image can be performed.

As explained in detail above, according to the present invention, character information and format information can be printed in one step, there is no need to store paper on which format information has been printed in advance, and only one type of paper can be used if the paper size is the same. It is possible to print documents in various formats, and furthermore, the electrical burden such as memory capacity does not become large, and since it is possible to print in two colors, it can meet the demand for color printing, and the value of its use is Extremely large.

[Brief explanation of the drawing]

Figures 1 to 5 are explanatory diagrams showing the development process using the positive-positive method, Figures 2 1 to 5 are explanatory diagrams showing the development process using the negative-positive method, and Figures 3 A to C are illustrations showing the method of the present invention. Explanatory diagram showing an example of a device for
1 to 5 are explanatory diagrams of the process according to the method of the present invention,
FIG. 5 is an explanatory diagram showing an example of the state of development carried out by the method of the present invention. In the figure, 18 is a photoreceptor, 20 is a charger, 22 is a reversal developer, 24 is a forward developer, and 34 is a static eliminator.

Claims (1)

[Scope of Claims] 1. The surface of a photoconductor is uniformly charged, a negative image is then projected, and reversal development is performed on the charge-eliminating portion of the surface of the photoconductor onto which light is projected, and then a positive image is projected and A process of removing static electricity from the residual charge area on the surface of the photoreceptor other than the positive image projection area, and performing forward development on the residual charge area of the positive projection area to form two types of toner images, negative and positive, on the same surface. An electrophotographic recording method comprising: 2. The electrophotographic recording method according to claim 1, wherein toners of different colors are used in reverse development and forward development.