JPH0517657U - Electrophotographic 2-color printer - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the non-contact developing method using a non-magnetic one-component developer is adopted as the developing method for the second color in the electrophotographic two-color printer, the second developing device portion is used. The printer of this type is capable of preventing the character loss of the second color based on the prevention of defective developer conveyance in the above, and thus extending the life of the second developing machine. [Structure] In an electrophotographic two-color printer, the second color development is non-contact development with a non-magnetic one-component developer, and the second color development is carried out. The present invention is characterized in that a block-shaped developer retention preventing means for preventing block-shaped developer pieces from accumulating is provided between the roll member and the elastic sheet-shaped member. As an example, as shown in FIG. 1, the roll member 7a in the second developing machine 7 for developing the second color.
Is reversely rotated during the non-printing operation.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to improvements in an electrophotographic two-color printer.

[0002]

[Prior Art]

 The electrophotographic two-color printer is used, for example, as shown in Table 1 below, for printing characters to be emphasized in text, and further, underlining.

[0003]

[Table 1]

FIG. 4 is an operation explanatory diagram of the printing unit in the conventional electrophotographic two-color printer. In FIG. 4, the surface of the photosensitive drum 1 is uniformly charged by the first charger 2 to a surface potential of about 700V. Further, the first laser beam 3 forms a latent image of a portion to be printed with black toner. Further, in the portion of the first developing device 4, the latent image of the black toner printed portion is developed by the black toner. On the other hand, by the second charger 5, the surface potential of the photosensitive drum 1 is uniformly charged again to about 700V. Further, the second laser beam 6 forms a latent image of a portion to be printed with a non-magnetic one-component developer, that is, color toner. Further, in the portion of the second developing device 7, the latent image of the color toner printed portion is developed by the non-magnetic one-component developer (color toner). Then, when a high voltage is applied to the transfer device 9 via the printing paper 8, the toner images of two colors on the photosensitive drum 1 are transferred to the printing paper 8. The printing paper 8 to which the toner image has been transferred is heated and pressed by a heat roll (not shown) and a back-up roller, and the toner image is fixed to the printing paper 8. The photosensitive drum 1 after the transfer of the toner image is discharged by the erase lamp 10, and the cleaner 11 cleans and removes the toner remaining on the photosensitive drum 1 after the transfer, and shifts to the next printing process. .. That is, by repeating the operation as described above, it becomes possible to print toner images of two colors at the same time as shown in Table 1. By the way, conventionally, in the electrophotographic two-color printer, when the second developing device 7 develops the second color (color), it is necessary to scrape off the image of the first color (black toner) already on the photosensitive drum 1. There is a problem that the image is disturbed due to the above, and further, the toner density is lowered. In consideration of such problems, the so-called non-contact developing method has been adopted previously. In the conventional non-contact developing method, as described in, for example, Japanese Patent Laid-Open No. 62-5270, the non-magnetic one-component developer in the second developing machine indicated by reference numeral 7 in FIG. The layer is thinned by the member 7b, and at the same time, electrostatic charge due to triboelectric charging is applied to the non-magnetic one-component developer. The non-magnetic one-component developer conveyed by the rotation of the roll member 7a reduces the distance between the roll member 7a and the photosensitive drum 1 to 0.5 mm or less by applying a voltage of 600 V to the roll member 7a. It flies through the set gap and adheres to the surface of the photosensitive drum 1.

[0005]

[Problems to be solved by the device]

 However, according to the conventional electrophotographic two-color printer adopting the non-contact developing method, the second developing machine for the non-magnetic one-component developer for developing the second color (color) has the following problems. was there. That is, when about 20,000 pages are printed, a partially unprintable area may occur and the second color may be missed. Therefore, in the conventional case, about 10,000 pages were printed as a guideline for the second development. I try to replace the machine. As described above, the reason why the second color is omitted is that the non-magnetic one-component developer, that is, the color toner piece is sandwiched between the roll member 7a and the elastic sheet-shaped member 7b such as silicon rubber, so that the roll member 7a is not covered. It is considered that this is because the non-magnetic one-component developer runs out, that is, the non-magnetic one-component developer is poorly conveyed. An object of the present invention is to improve the printing reliability of an electrophotographic two-color printer which eliminates the above-mentioned drawbacks of the prior art and adopts a non-contact developing method using a non-magnetic one-component developer as a second color developing method. Another object of the present invention is to provide a printer of this kind which can extend the life of the second developing machine.

[0006]

[Means for Solving the Problems]

 The above-mentioned object is an electrophotographic two-color system including a first and second charging device, first and second optical systems, first and second developing devices, and one transfer device around one photosensitive drum. In the printer, the second color development is non-contact development with a non-magnetic one-component developer, and it is located in the second developing machine that develops the second color and is elastically connected to the roll member in the second developing machine. This is achieved by providing a lump developer retention preventing means for preventing lump developer pieces from accumulating between the sheet-shaped members.

[0007]

[Action]

 Therefore, according to the present invention having the above-described structure, even when the non-contact developing method using the non-magnetic one-component developer is adopted as the developing method for the second color in the electrophotographic two-color printer, In addition, it is possible to prevent the character loss of the second color based on the prevention of the developer conveyance failure in the second developing machine portion, and to extend the life of the second developing machine.

[0008]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is an operation explanatory view of a printing unit showing an embodiment of an electrophotographic two-color printer according to the present invention, which is the same as the conventional example shown in FIG. The reference numerals indicate the same parts. That is, in FIG. 1, in the case of performing ordinary printing, a rotatable roll made of, for example, a conductive brush is rotated with respect to a rotatable aluminum roll member 7a in the second developing machine 7, for example, a sandblasted surface thereof. Possible developer coating member 7c deposits a non-magnetic one-component developer. Further, a thin developer layer is formed on the surface of the roll member 7a by bringing the elastic sheet member 7b made of, for example, silicon rubber into contact with the roll member 7a. Then, in normal printing, the roll member 7a rotates in the direction opposite to the rotation direction of the photosensitive drum 1 (direction A). On the other hand, during the so-called non-printing operation such as when the printer is powered on or when the state where the printing paper 8 is exhausted is detected, the roll member 7a is moved forward (B direction) for a certain time with respect to the rotation direction of the photosensitive drum 1. ), It is possible to remove the developer pieces (lumps) accumulated between the roll member 7a and the elastic sheet-shaped member 7b, that is, the developer pieces (lumps) that hinder the conveyance of the non-magnetic one-component developer. FIG. 2 is an operation explanatory view of the second developing machine 7 showing the second embodiment of the printer of the present invention. That is, in the embodiment shown in FIG. 2, the roll member 7a of the second developing machine 7 is provided with a rotatable developer peeling member 7d such as rayon, which is charged with a polarity different from that of the non-magnetic one-component developer. The developer adhered to the surface of the roll member 7a is once peeled off from the roll member 7a before the developer is applied to the roll member 7a by bringing them into contact with each other. According to this, also by this, it is possible to eliminate the defective conveyance of the non-magnetic one-component developer on the roll member 7a. FIG. 3 is an operation explanatory view of the second developing machine 7 showing a third embodiment of the printer of the present invention. That is, in the embodiment of FIG. 3, the contact portion (point C) between the elastic sheet-shaped member 7b and the roll member 7a of the second developing machine 7 is moved in the time direction from the lowermost portion (point D) of the roll member 7a. It was installed at a position of 90 ° ± 30 °, and according to the experiment, it was possible to eliminate the defective conveyance of the non-magnetic one-component developer on the roll member 7a. As described above, according to the present invention including the embodiments of FIGS. 1 to 3, the non-contact developing method using the non-magnetic one-component developer is used as the developing method of the second color in the electrophotographic two-color printer. Even when adopted, it prevents the developer particles in the form of agglomerate from accumulating between the roll member 7a and the elastic sheet member 7b in the second developing machine 7 and causes the developer conveyance failure in the second developing machine 7 part. It is possible to prevent the character loss of the second color based on the prevention, and to extend the life of the second developing machine 7. As a modified example of the present invention, there is no problem in carrying out by appropriately combining the configurations of FIGS.

[0009]

[Effect of the device]

 The present invention has been described above, and according to the present invention, the printing reliability of the electrophotographic two-color printer which employs the non-contact developing method using the non-magnetic one-component developer as the second color developing method. It is possible to provide a printer of this kind which can be improved and the life of the second developing machine can be extended.

[Brief description of drawings]

FIG. 1 is an operation explanatory diagram of a printing unit showing an embodiment of an electrophotographic two-color printer according to the present invention.

FIG. 2 is an operation explanatory view of a second developing device 7 showing a second embodiment of the printer of the present invention.

FIG. 3 is an operation explanatory view of a second developing device 7 showing a third embodiment of the printer of the present invention.

FIG. 4 is an operation explanatory diagram of a printing unit in a conventional electrophotographic two-color printer.

[Explanation of symbols]

1 ... Photosensitive drum, 2 ... 1st charger, 3 ... 1st laser beam,
4 ... 1st developing machine, 5 ... 2nd charger, 6 ... 2nd laser beam,
7 ... 2nd developing machine, 7a ... Roll member, 7b ... Elastic sheet-shaped member, 7c ... Developer application member, 7d ... Developer peeling member, 8 ... Printing paper, 9 ... Transfer device, 10 ... Erase lamp, 11 ... Cleaner.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Kotaro Yamada, Inventor, Kotaro Yamada 1060 Takeda, Katsuta City, Ibaraki Prefecture Hitachi Koki Co., Ltd.

Claims (8)

[Scope of utility model registration request] 1. An electrophotographic system 2 comprising a first and second charging device, first and second optical systems, first and second developing devices, and one transfer device around one photosensitive drum. In the color printer, the development of the second color is non-contact development with a non-magnetic one-component developer, and is located in the second developing machine for developing the second color,
An electrophotographic two-color printer comprising a block developer retention preventing means for preventing block developer pieces from accumulating between a roll member and an elastic sheet member in the second developing machine. 2. A second developing means for developing a second color according to claim 1.
An electrophotographic two-color printer characterized in that a roll member in a developing machine is reversely rotated during a non-printing operation. 3. The roll member of claim 2, wherein the roll member of the second developing device is charged with a polarity different from that of the non-magnetic one-component developer.
An electrophotography characterized in that a rotatable developer peeling member is brought into contact with the roll member, and before the developer is applied to the roll member, the developer adhered to the surface of the roll member is once peeled from the roll member. Two-color printer. 4. The electronic device according to claim 1, wherein the contact portion between the elastic sheet-like member of the second developing device and the roll member is installed at a position of 90 ° ± 30 ° from the lowermost portion of the roll member. Photographic two-color printer. 5. The second developing device for developing a second color according to claim 1.
The roll member in the developing machine is reversely rotated at the time of non-printing operation, and the rotatable developer peeling member, which is charged with a polarity different from that of the non-magnetic one-component developer, is brought into contact with the roll member of the second developing machine. An electrophotographic two-color printer characterized in that the developer adhering to the surface of the roll member is once peeled off from the roll member before the developer is applied to the roll member. 6. The second developing device according to claim 1, wherein the second color is developed.
The roll member in the developing machine is reversely rotated during non-printing operation, and the contact portion between the elastic sheet-shaped member of the second developing machine and the roll member is 90 ° ± 30 ° from the lowermost part of the roll member.
An electrophotographic two-color printer characterized by being installed at the position. 7. The roll member of claim 2, wherein the roll member of the second developing device is charged with a polarity different from that of the non-magnetic one-component developer.
Before applying the developer to the roll member by bringing the rotatable developer peeling member into contact with the roll member, the developer adhering to the surface of the roll member is once peeled from the roll member, and An electrophotographic two-color printer characterized in that a contact portion between an elastic sheet member and a roll member is installed at a position of 90 ° ± 30 ° from the lowermost part of the roll member. 8. The second developing system according to claim 1, wherein the second color is developed.
The roll member in the developing machine is reversely rotated at the time of non-printing operation, and the rotatable developer peeling member, which is charged with a polarity different from that of the non-magnetic one-component developer, is brought into contact with the roll member of the second developing machine. Before the developer is applied to the roll member, the developer adhering to the surface of the roll member is once peeled off from the roll member, and the elastic sheet member of the second developing machine is contacted with the roll member. The electrophotographic two-color printer is characterized in that the section is installed at a position of 90 ° ± 30 ° from the lowermost part of the roll member.