JPH03235979A - Electrostatic recording device - Google Patents

Abstract

PURPOSE:To eliminate the influence of triboelectrostatic charging caused between a metallic cleaning blade and an image carrier which has an aluminum oxide film on the surface by applying a voltage to a cleaning blade by a voltage applying means. CONSTITUTION:A dielectric drum 1 is formed of an aluminum drum which has the aluminum oxide film 2 on the surface and the metallic cleaning blade 18 is pressed against the surface of the dielectric drum 1 so as to remove toner, paper powder, etc., remaining on the surface after a transfer and a fixing process. In this case, the specific voltage is applied to the cleaning blade 18 by a power source 21 as the voltage applying means. Consequently, even when the metallic blade 18 is used, the surface of the image carrier 1 is prevented from being charged triboelectrostatically to prevent an image from fogging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrostatic recording device that records an image by forming an electrostatic latent image using ions.

[Prior Art] Conventionally, as this type of electrostatic recording device, there are the following types. That is, as shown in FIG. 8, a dielectric drum 50 having an aluminum oxide coating is rotatably held, and an electrostatic recording head 5 is mounted on the surface of the dielectric drum 5O.
1, an electrostatic latent image is written. Then, the electrostatic latent image written on the dielectric drum 50 is transferred to a developing device 52.
to form a toner image. This toner image is transferred onto the recording paper 54 and fixed at the same time by passing the recording paper 54 between the dielectric drum 50 and the pressure contact drum 53 that is in pressure contact with the dielectric drum 50. Toner and paper dust remaining on or attached to the dielectric drum 50 are removed by a cleaning blade 55, and residual charges are erased by a static eliminator 56 in preparation for the next image forming process.

The cleaning blade 55 is made of a metal blade that comes into pressure contact with the surface of the dielectric drum 50, and scrapes off toner, paper dust, etc. adhering to the surface of the dielectric drum 50. Further, the snow remover 56 is configured to generate corona discharge by applying an alternating current voltage, and is used to erase charges remaining on the surface of the dielectric drum 50.

[Problems to be Solved by the Invention] However, the above prior art has the following problems. That is, the cleaning blade 55
is made of a metal blade, and when the cleaning blade 55 removes toner remaining on the surface of the dielectric drum 50, the surface of the dielectric drum 50 is rubbed by the cleaning blade and the dielectric drum 50. Frictionally charged. Due to this frictional charging, the surface of the dielectric drum 50 may be charged to a polarity opposite to that of the electrostatic latent image formed on the surface. Therefore, the dielectric drum 5
Even after the static electricity is removed by the static eliminator 56, a charge having a polarity opposite to that of the electrostatic latent image remains on the surface of the 0, and the potential contrast between the electrostatic latent image after static electricity removal and this triboelectric charge becomes large. Therefore, when conductive toner or the like is used in the developing device 52, the triboelectrically charged area on the dielectric drum 50 is developed due to the potential contrast, and the toner adheres to the area, causing problems such as image fogging. there were.

In order to solve the above problems, cleaning blade 5
5, it is also conceivable to use a material made of synthetic resin or the like that does not cause frictional charging between it and the dielectric drum 50.

However, in such a case, a new problem arises in that the cleaning blade 55 cannot sufficiently remove the toner etc. remaining on the surface of the dielectric drum 50 because the elastic modulus of synthetic resin etc. is smaller than that of metal. arise.

[Means for Solving the Problems] Therefore, the present invention has been made to solve the problems of the prior art described above, and its purpose is to use a metal blade as a blade for cleaning the surface of an image carrier. To provide an electrostatic recording device which prevents the surface of an image bearing member from being charged to a polarity that causes harmful effects due to frictional charging, and which does not cause fogging, etc., even when using a blade made of aluminum.

That is, the present invention provides an image carrier having an aluminum oxide coating on its surface, an electrostatic recording head that forms an electrostatic latent image on the surface of the image carrier, a developer that develops the electrostatic latent image, and a developer that develops the electrostatic latent image. The image carrier is configured to include a metal cleaning blade provided in contact with the surface of the image carrier, and voltage application means for applying a predetermined voltage to the cleaning blade.

The cleaning blade may be made of, for example, mild steel, hard steel, or stainless steel.

[Function] In the present invention, by applying a voltage to the cleaning blade by the voltage applying means, even if frictional charging occurs between the metal cleaning blade and the image carrier having an aluminum oxide coating on the surface, The effect of this frictional charging is prevented.

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows an embodiment of an electrostatic recording device according to the present invention. In the figure, reference numeral 1 denotes a dielectric drum as an image carrier, and the dielectric drum 1 is formed of an aluminum drum having an anodized aluminum oxide coating 2 on its surface. The dielectric drum 1 is rotatably provided in the direction of the arrow, and an electrostatic latent image of negative polarity, for example, is written on its surface by an electrostatic recording head 3.

As shown in FIG. 3, this electrostatic recording head 3 has a plurality of driving types t15.
... are provided in parallel to each other, and a plurality of control electrodes 6.6 ... are provided on the back surface thereof so as to intersect with these drive electrodes 5.5 ..., and the picture electrodes 5.5 ...・
・The matrix is made up of 6.6 rivers. The control electrodes 6.6, . . . include drive electrodes 5.5.
Openings 7.7... are formed at positions that intersect with.... In addition, on the lower surface of the control electrodes 6.6...
As shown in FIG. 2, a screen electrode 9 is provided with an insulating layer 8 interposed therebetween.

These insulating layer 8 and screen electrode 9 are provided with openings 10.10 and ion extraction openings 11 at positions corresponding to openings 7.7 of control electrodes 6.6. ．．
11... are formed.

As shown in FIG. 2, the electrostatic recording head 3 applies a high frequency high voltage between the drive electrodes 5,5... and the screen electrode 9, and also applies a DC voltage to the screen electrode 9. In addition, a pulse voltage corresponding to the image information is applied to the control electrodes 6, 6, . . . . By doing this, a creeping corona discharge is generated in the opening 7.7 between the drive electrode 5.5 and the control electrode 6.6, and the ions generated by this creeping corona discharge are of,
The ions are accelerated or absorbed by the electric field formed between the control electrodes 6, 6... and the screen electrode 9, and the ion emission is controlled to form an electrostatic latent image using ions according to the image signal. It has become. In the figure, reference numeral 12 indicates a head substrate covering the surface of the drive electrodes 5.5.

The electrostatic latent image written by the electrostatic recording head 3 is
As shown in FIG. 1, the toner image is developed by a developing device 13 using pressure-fixed toner or the like to form a toner image. This toner image is transferred onto the recording paper 15 and fixed at the same time by a pressure drum 14 that is in pressure contact with the surface of the dielectric drum 1 . The recording paper 15 is fed by a feed roller 16 from a paper feed cassette (not shown) to the surface transfer position of the dielectric drum 1, and the recording paper 15 on which the toner image has been transferred and fixed is
It is conveyed to the outside of the apparatus by feed rollers 17.

In this way, untransferred toner, paper dust from the recording paper 15, and the like remain attached to the surface of the dielectric drum 1 after the toner image transfer and fixing process has been completed. This is because the toner image is transferred and fixed onto the recording paper 15 by the pressing force of the pressure drum 14, which is brought into contact with the surface of the dielectric drum 1 under high pressure.

A metal cleaning blade 18 is pressed onto the surface of the dielectric drum 1 in order to remove residual toner, paper dust, etc. after the transfer and fixing process. As shown in FIG. 4 or FIG. 5, this cleaning blade 18 is provided with its base end 18a fixed to a support member 19. The metal material forming the cleaning blade 18 includes the aluminum oxide coating 2 on the surface of the dielectric drum 1.
has a hardness of 7 to 8 on the Mohs scale, so it is preferable that the metal has a hardness lower than this so as not to damage the aluminum oxide coating 2. In addition, considering the wear of the cleaning blade 18, for example, mild steel (hardness 5 to 6) is used.
), stainless steel (hardness 5-6), hard steel (hardness 6-6.
5) etc. are used.

Furthermore, although the cross-sectional shape of the cleaning blade 18 is arbitrary, if it is flat as shown in FIG. Since the cleaning blade 18 has a knife shape as shown in FIG.
It is also possible to use one formed into a knife shape. The thickness of the cleaning blade 18 is appropriately set depending on the elastic modulus of the selected metal material, and for example, the thickness is 100 mm.
μm is used. In the figure, T indicates toner and the like removed by the blade 18.

Further, on the downstream side of the cleaning blade 18, a static eliminator 20 is provided for erasing charges remaining on the surface of the dielectric drum 1. The static eliminator 20 is constituted by a corona discharger, and generates positive and negative ions by applying an alternating current voltage to attenuate and eliminate the residual charge on the surface of the dielectric drum 1.

By the way, in addition to the above-described configuration, this embodiment is configured to include a voltage application means for applying a predetermined voltage to the cleaning blade.

That is, as shown in FIG. 1, a predetermined negative DC voltage is applied to the cleaning blade 18 by a power source 21 serving as a voltage applying means. The reason why the voltage applied to the cleaning blade 18 is negative is to match the polarity of the electrostatic latent image formed on the surface of the dielectric drum 1. The reason why a voltage is applied to the cleaning blade 18 is to cancel the frictional electrification of the surface 0 of the dielectric drum 1 when the surface of the dielectric drum 1 is rubbed by the cleaning blade 18 . Therefore, the magnitude and polarity of the voltage applied to the cleaning blade 18 are different between the cleaning blade 18 and the dielectric drum 1.
It is set according to the polarity and magnitude of frictional electrification.

EXPERIMENTAL EXAMPLE In order to confirm the effects of the present invention, the present applicants conducted an experiment in which an image was actually formed using a resetting blade 18 as shown in FIG. cleaning blade 18
A material made of stainless steel (SUS304) was used. Further, on the surface of the dielectric drum 1, as shown in FIG.
As shown in a), an image was formed with -200 V in the image area and approximately OV in the non-image area. Furthermore, a voltage of −20 to −50 V was applied to the cleaning blade 18 by a power source 21.

The cleaning blade 18 was used to clean the surface of the dielectric drum 1 after the transfer and fixing process. As a result, the surface potential of the dielectric drum 1 was 11100 V in the image area and -20 V in the non-image area, as shown in FIG. 6(b). Further, the surface potential of the dielectric drum 1 after snow removal was 20 V in the image area and 110 V in the non-image area, as shown in FIG. 6<C>. As described above, since the potential difference between the non-image area and the image area was only about 10 V, no fogging occurred in the non-image area during the next image recording.

In this way, if the potential difference between the image area and the non-image area on the surface of the dielectric drum 1 is small, for example, even if a conductive toner that is developed by a potential difference is used as the developing toner, Since it is possible to prevent the non-image area from being charged to a polarity opposite to the potential of the image area due to frictional charging with the cleaning blade 18, it is possible to reliably prevent the occurrence of fogging and the like.

As described above, the application of voltage by the power supply 21 to the cleaning blade 18 has the effect of adjusting the charging polarity of the surface of the dielectric drum 1 before static electricity removal, and making the potential of each part uniform to facilitate static electricity removal.

2 Comparative Example Under the same conditions as in the above experimental example, a test was conducted to determine what happens to the potential of the dielectric drum surface before and after cleaning when the cleaning blade 18 is grounded. Dielectric drum 1
As shown in FIG. 7(a), an image of 1200 V in the image area and approximately OV in the non-image area was formed on the surface of the sample, as shown in FIG. 7(a).

The cleaning blade 18 was used to clean the surface of the dielectric drum 1 after the transfer and fixing process. As a result, as shown in FIG. 7(b), the surface potential of the dielectric drum 1 was 1100 cm in the image area, but the surface potential in the non-image area was +2
It was charged to 0V. Furthermore, the surface potential of the dielectric drum 1 after static elimination is 120 V in the image area and +10 V in the non-image area, as shown in FIG. 7(C).
It became. As described above, the potential difference between the non-image area and the image area was as large as 30 V, and fogging occurred during the next image recording.

In the above embodiment, a case has been described in which three power sources 21 are used as the voltage applying means, but the present invention is not limited to this, and a resistor may be used instead of the power source.

In addition, in the illustrated embodiment, the cleaning blade 1 is simply
Although the case where the toner etc. remaining on the surface of the dielectric drum 1 is removed by the cleaning blade 18 has been described, the toner etc. removed by the cleaning blade 18 may of course be removed by suction.

[Effects of the Invention] This invention has the above-described configuration and operation, and even when a metal blade is used as the blade for cleaning the surface of the image carrier, the surface of the image carrier is free from harmful effects due to frictional electrification. Since charging to the generated polarity can be prevented, it is possible to provide an electrostatic recording device that does not cause fogging or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an electrostatic recording device according to the present invention, FIGS. 2 and 3 are a cross-sectional view and a plan view showing an electrostatic recording head, and FIGS. 4 and 5 are Configuration diagrams showing different examples of cleaning blades, Figures 6(a), (b), and (C) are graphs showing the effects of experimental examples, and Figures 7(a), (b), and (C) are graphs showing the effects of experimental examples. A graph showing the effect of the comparative example, and FIG. 8 is a configuration diagram showing a conventional device. [Explanation of symbols] 1...Dielectric drum 2...Aluminum oxide coating 3...Electrostatic recording head 13...Developer 18...Cleaning blade 21...Power supply patent applicant Fuji Xerox Co., Ltd. Representative Patent Attorney Tomohiro Nakamura (1 other person) 21: Power supply diagram - 13 6 803 - () ■

Claims (1)

[Claims] an image carrier having an aluminum oxide coating on its surface; an electrostatic recording head that forms an electrostatic latent image on the surface of the image carrier;
A developing device for developing the electrostatic latent image, a metal cleaning blade provided in contact with the surface of the image carrier, and a voltage application means for applying a predetermined voltage to the cleaning blade. An electrostatic recording device characterized by: