JPS6224293Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transfer type electrostatic copying machine, and more specifically, the present invention relates to a transfer type electrostatic copying machine, and more specifically, the invention relates to a transfer type electrostatic copying machine, and more particularly, to a transfer type electrostatic copying machine, in which a magnetic toner developed by a polarization phenomenon, a so-called one-component magnetic toner, is used to transfer the surface of a photoreceptor. The present invention relates to a transfer type electrostatic copying machine in which residual toner is cleaned using a magnetic brush.

Conventionally, in electrostatic transfer copying machines that use one-component magnetic toner as a developer, it has been extremely difficult to clean the photoreceptor. Two-component developers consisting of a carrier such as iron powder and an insulating toner are effectively cleaned by a fur brush cleaning method or a rubbing cleaning method using a web or an elastic wiping plate. . These cleaning methods cannot be applied to one-component magnetic toners. To explain the reason, first of all, the fur brush cleaning method is
By rubbing the surface of the photoconductor after transfer with a fur brush that rotates at high speed, the toner remaining on the photoconductor surface is knocked off, and the toner that is charged in the previous process is charged by the tip of the fur brush that is charged by friction. This device electrostatically captures the toner that is being used. However, since the one-component magnetic toner has a very small amount of charge, it cannot be captured by the fur brush, and therefore a good cleaning effect cannot be obtained. Next, in the rubbing cleaning method, a highly hard metal magnetic powder such as iron oxide contained in a one-component magnetic toner is interposed between the photoreceptor surface and a web or an elastic wiping plate. This is because it scratches the surface of the photoreceptor.

In addition, in a transfer type electrostatic copying machine that uses insulating toner that can be charged to a certain polarity by frictional charging,
A cleaning method using a magnetic brush is known (JP-A-52-76932, JP-A-50-122938, etc.). In this cleaning method, a bias potential with a polarity opposite to that of the toner is applied to the cleaning magnetic brush, and the electrostatic attraction generated by the toner's charge and the bias potential creates an electrostatic adhesion force between the toner and the photoreceptor surface. The residual toner on the surface of the photoreceptor is efficiently deposited on the cleaning magnetic brush to perform cleaning. When this cleaning method is applied to one-component magnetic toner, when a bias potential is applied to the magnetic brush, the toner present on the surface of the magnetic brush is polarized and charged, and the surface of the photoreceptor to be cleaned is developed and a satisfactory result is obtained. Unable to perform cleaning.

An object of the present invention is to provide a transfer type electrostatic copying machine that uses a one-component magnetic toner as a developer, which easily and reliably removes toner remaining on the surface of a photoreceptor after image transfer using a magnetic brush. It is in.

FIG. 1 is a simplified cross-sectional view of one embodiment of the present invention. A photoreceptor 2 is provided endlessly around the entire circumferential surface of a drum 1 which is rotated during copying. This drum 1 is rotationally driven in the direction of arrow 3. drum 1
A charging corona discharger 4, an exposure means 5, a magnetic brush developing means 6, a corona discharger 7,
Static elimination lamp 8, magnetic brush cleaning means 10
is placed. In this electrostatic transfer copying machine, one copying process is completed by the drum 1 rotating twice during copying.

During the first rotation of the drum 1 and therefore the photoreceptor 2, the photoreceptor 2 provided on the outer peripheral surface of the drum 1
is charged either positively or negatively by the charging corona discharger 4, depending on the electrical characteristics of the photoreceptor 2. The following explanation will be given as a negative charge, but the same applies to a positive charge, only the polarity is reversed. The exposure means 5 irradiates the charged surface of the photoreceptor 2 with a light image corresponding to the original, thereby forming an electrostatic latent image on the surface of the photoreceptor 2 . In the developing means 6, a one-component polarizable magnetic toner 1 is attached to the surface of a magnetic brush 11 by magnetic force.
2 is applied to the surface of the photoreceptor 2, and the electrostatic latent image is visualized. The visualized toner image is transferred onto a transfer paper 13 that is conveyed in synchronization with the rotation of the photoreceptor 2 in the rotation direction 3 by the discharge of the corona discharger 7 . This corona discharger 7 preferably uses the same polarity as the charging polarity, that is, negative corona discharge. The transferred transfer paper 13 is conveyed to a fixing device (not shown).

During the second rotation of the photoreceptor 2, the charging corona discharger 4 and the exposure means 5 are stopped, and the corona discharger 7 is stopped.
Then, the static eliminating lamp 8 is energized, and the residual toner on the photoreceptor 2 is cleaned by the magnetic brush cleaning means 10.

The configuration of the magnetic brush cleaning means 10 is as follows.
This will be explained in the figure. A hollow cylindrical sleeve 21 made of non-magnetic material is rotatably provided, and a cylindrical magnet 20 is installed inside this sleeve 21.
is provided. The rotational direction 22 of the sleeve 21 and the rotational direction 3 of the photoreceptor 2 are the same direction, so the running directions of the outer circumferential surface of the sleeve 21 and the surface of the photoreceptor 2 are opposite at the opposing portions thereof. Further, a certain amount of one-component magnetic toner is applied and held on the sleeve 21 in advance. During cleaning, the toner previously held in the sleeve 21 is rubbed on the surface of the photoreceptor 2 to separate the toner remaining on the surface of the photoreceptor 2 from the surface, and then captured on the sleeve 21 by magnetic force. It is something.

The magnetic brush cleaning means 10 may be of any configuration as long as it can magnetically attach toner and rub the surface of the photoreceptor 2 with the formed magnetic brush.

FIG. 2 shows the state of the surface of the photoreceptor 2 immediately after the transfer during the first rotation of the photoreceptor 2. FIG. The residual toner 15 is polarized and is attracted to the negative charges of the photosensitive layer 16 on the surface of the photoreceptor 2 . Furthermore, positive charges are induced in the conductive base 17 on the lower surface of the photosensitive layer 16 of the photoreceptor 2 in correspondence with the negative charges of the photosensitive layer 16. In order to remove the residual toner 15 from the surface of the photoreceptor 2 during the second rotation of the photoreceptor 2 in such a state immediately after transfer, the electrostatic attraction between the residual toner 15 and the photosensitive layer 16 is reduced by magnetic brush cleaning. It is necessary that the magnetic attraction between the cleaning magnetic brush 18 of the means 10 and the residual toner 15 be sufficiently weaker.

According to the present invention, in order to clean the residual toner on the photoreceptor 2 during the second rotation of the photoreceptor 2,
During the second rotation of the photoreceptor 2, the corona discharger 7 and the static elimination lamp 8 are energized. That is, during the second rotation of the photoreceptor 2 after the transfer, the photoreceptor 2 is first charged by the corona discharger 7 as shown in FIG. During the first rotation of the photoreceptor 2, the corona discharger 7 performs a discharge of the same polarity as the discharge during transfer, that is, a negative discharge in this embodiment. As a result, negative charges increase on the free surface of the toner 15 and the toner 1 on the photosensitive layer 16 increases.
The negative charge also increases on the surface to which 5 is not attached. A positive charge remains on the surface of the toner 15 adhering to the photosensitive layer 16. Further, positive charges are induced in the conductive base 17 in correspondence with the negative charges of the photosensitive layer 16. As shown in the third figure, when the corona discharge is performed by the corona discharger 7, the toner 15 has an increased negative charge, so the toner 15 and the photosensitive layer 16
The electrostatic attraction between them is considerably weaker than in the state immediately after transfer shown in FIG.

After corona discharge by the corona discharger 7,
Next, the photosensitive layer 16 of the photoreceptor 2 is uniformly exposed to light using the static elimination lamp 8. This state is shown in FIG. Photosensitive layer 16 to which toner 15 is not attached
The surface of the conductive base 17 neutralizes the positive charge and the negative charge disappears. Therefore, even if the photosensitive layer 16 approaches the cleaning magnetic brush 18 in the magnetic brush cleaning means 10 in this state, the toner 15 on the surface of the cleaning magnetic brush 18 will not be polarized, and the toner on the surface of the cleaning magnetic brush 18 will not be polarized. The toner 15 is not adsorbed to the photosensitive layer 16 again. Note that the surface of the photosensitive layer 16 to which the toner 15 is attached remains as it is and maintains a negative charge state.

When the photoreceptor 2 in the state shown in FIG. The residual toner 15 is attracted by the magnetic attraction of the cleaning magnetic brush 18, which overcomes the electrostatic attraction between it and the photosensitive layer 16.

As is clear from FIG. 1, the charging corona discharger 4 and the exposure means 5 are arranged at positions in the circumferential direction of the photoreceptor 2 where the light from the static elimination lamp 8 is blocked by the photoreceptor 2 and does not reach them. ing. Therefore, photoreceptor 2
At the latest at the start of the second rotation, it is possible for the static elimination lamp 8 to be turned on, so that by the end of one rotation just after the second rotation, the entire circumferential surface of the photoconductor 2 is covered with electricity. It becomes possible to perform cleaning over the entire area.

Next, the reason why the corona discharger 7 must have the same polarity as the charging corona discharger 4 will be described below. FIG. 5 shows a state immediately after transfer (FIG. 3) in which a corona discharger 7 generates a discharge of opposite polarity to the charging corona discharge, that is, a positive discharge. That is, the residual toner 15 is positively charged over the entire surface. The surface of the photosensitive layer 16 to which the residual toner 15 is not attached is also positively charged. The surface of the photosensitive layer 16 that is attached to the residual toner remains negatively charged. Further, the entire surface of the conductive base 17 has a negative polarity. Therefore, the electrostatic attraction between the residual toner 15 and the photoreceptor 2 increases by the amount of the positive charge of the residual toner 15. FIG. 6 shows a state in which the photosensitive layer 16 is uniformly exposed to light by the static elimination lamp 8 in this state.
The surface to which residual toner 15 is not attached neutralizes the negative charge of the conductive base 17, and the positive charge disappears. However, the surface to which the residual toner 15 is attached remains as it is. In the above state, the electrostatic attraction between the residual toner 15 and the photosensitive layer 16 is the same as in FIG.
The increase is due to the increase in the positive charge of . Therefore, the residual toner 15 is not cleaned.

Examples of the present invention are described below.

Example 1 A photoconductor 2 made of polyvinylcarbazole sensitized with tetranitrofluorenone was used.
During the first rotation, the surface of the photoreceptor 2 is charged to about -300 V by applying corona discharge of -7 KV with the charging corona discharger 4, and then an electrostatic latent image is formed by the exposing means 5. Next, a toner image is created using the developing magnetic brush 11, and the toner image is applied from the back side (non-transfer side) of the transfer paper using a corona discharger 7.
The photoreceptor 2 is exposed to a 5.2KV corona discharge.
The image is transferred onto a transfer paper 13 that is conveyed in synchronization with the image data.
During the second rotation of the photoconductor 2, the remaining toner that was not transferred is given a corona discharge of minus 5.2 KV by the corona discharger 7, and then uniformly discharged with a 10W white fluorescent lamp as the static elimination lamp 8. Apply exposure. In this state, the residual toner that reached the cleaning magnetic brush 18 was completely removed from the surface of the photoreceptor.

Example 2 The same procedure as in Example 1 was carried out using zinc oxide as the photoreceptor 2, and the residual toner was completely removed from the surface of the photoreceptor 2.

Example 3 The same procedure as in Example 1 was carried out using Se as the photoreceptor 2, and the residual toner was completely removed from the surface of the photoreceptor 2.

As described above, according to the present invention, in a transfer-type electrostatic copying machine using one-component magnetic toner, the processes of charging, exposing, developing, and transferring are performed during the first rotation of the photoconductor, and cleaning is performed during the second rotation of the photoconductor to visualize the electrostatic latent image, so that the residual toner on the photoconductor surface after transfer can be easily and reliably cleaned. In particular, the corona discharger energized for the purpose of transfer during the first rotation of the photoconductor is arranged to charge the photoconductor with the same polarity as during transfer for the purpose of cleaning during the second rotation of the photoconductor, thereby simplifying the structure.

The charging corona discharger 4 and the exposure means 5 are arranged at positions in the circumferential direction of the photoreceptor 2 where the light from the static elimination lamp 8 is blocked by the photoreceptor 2 and does not reach, so that the exposure by the exposure means 5 is not possible. Regardless of the operation, the static elimination lamp 8 can be turned on during the second rotation of the photoconductor 2, and therefore the second rotation of the photoconductor 2
It becomes possible to clean the entire circumferential surface of the photoreceptor 2 by just making one rotation at the rotation point. In this way, the photoreceptor 2 only needs to be rotated twice to perform complete cleaning over the entire circumference of the photoreceptor, and there is no need for further rotations of the photoreceptor 2, allowing for continuous copying. The time required for each copying process can be shortened. Furthermore, by rotating the photoreceptor 2 twice, the entire circumferential surface of the photoreceptor 2 is cleaned, so the circumference of the photoreceptor can be set to the maximum length of the document to be copied. It becomes possible to efficiently use the photoreceptor along its circumferential length, thereby making it possible to downsize the photoreceptor 2. In addition, in this invention, the photoreceptor 2
In the second rotation, the toner remaining on the surface of the photoreceptor 2 is removed by the magnetic brush developing means 6 and the magnetic brush cleaning means 10, so that the toner is reliably removed.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional view of an embodiment of the present invention, FIG. 2 is a diagram of the charging state of the residual toner 15 and the photoreceptor 2 immediately after the transfer, and FIG. 3 is a corona with the same polarity as the charging. Figure 4 is a diagram showing the state when a discharge occurs, Figure 4 is a diagram showing the state when uniform exposure is performed after the above corona discharge, Figure 5 is a diagram showing the state when a corona discharge with the opposite polarity to the charging is performed, Figure 6
The figure is a diagram showing a state in which uniform exposure was performed after corona discharge with opposite polarity. DESCRIPTION OF SYMBOLS 1... Drum, 2... Photoreceptor, 4... Charging corona discharger, 5... Exposure means, 6... Magnetic brush developing means, 7... Corona discharger, 8... Static elimination lamp, 10... Magnetism brush cleaning means, 15
...Residual toner, 16...Photosensitive layer, 17...Conductive base.

Claims (1)

[Claims for Utility Model Registration] A charging corona discharger 4, an exposure means 5, This includes a magnetic brush developing means 6 using a one-component polarizable magnetic toner, a transfer corona discharger 7, a static elimination lamp 8, and a magnetic brush cleaning means 10 using a one-component polarizable magnetic toner. The charging corona discharger 4 and the exposure means 5 are arranged in a position in the circumferential direction of the photoreceptor 2 where the light from the static elimination lamp 8 is blocked by the photoreceptor 2 and does not reach the photoreceptor. 2, the charged corona discharger 4
The photoreceptor 2 is given photosensitivity and charged, an electrostatic latent image corresponding to the original is created on the photoreceptor 2 exposed by the exposure means 5, and the developed image is transferred to a charging corona discharger. 7 onto a transfer paper, and during the second rotation of the photoreceptor 2, the charged corona discharger 4
The exposure means 5 is stopped, the transfer corona discharger 7 is energized to charge the photoreceptor 2 to the same polarity as during transfer, and the static elimination lamp 8 is energized. Electric copying machine.