JPH03116179A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent developer from adhering to the control electrode of an electrostatic charger and to uniformly electrostatically charge an image carrier by allowing the developer which leaks from a developing means or a cleaning means to adhere to an impressing means. CONSTITUTION:Conductive members 31 and 32 are respectively disposed along a photosensitive drum 2 between a scorotron charger 3 and a developing device 5 and between the scorotron charger 3 and a cleaning device 8. At the time of forming an image, toner t which is electrostatically charged to be positive leaks from the developing device 5 and the cleaning device 8 and suspends, and it is going to adhere to a grid 25 of the scorotron charger 3, which is electrostatically charged to be negative. However, the suspending toner t is attracted to the conductive members 31 and 32 which are electrostatically charged to be negative on the way to the grid 25. Thus, the toner t does not adhere to the grid 25 and the unevenness of discharge of the charger 3 is surely prevented, then the photosensitive drum 2 is uniformly electrostatically charged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus used as, for example, an electronic rear-photographer.

(Prior Art) In an electronic copying machine, the surface of a photosensitive drum is uniformly charged by a charger, an electrostatic latent image is formed on the charged surface of the photosensitive drum, and this electrostatic latent image is developed by a developing device. After toner is supplied and developed, this toner image is transferred onto paper by a transfer charger. Then, the paper to which this toner image has been transferred is peeled off from the photosensitive drum by a peeling charger, and then sent to a fixing device to fix the image. Then, after this image is fixed, the paper is discharged onto a paper discharge tray via a paper discharge roller.

Further, after the image transfer, the toner remaining on the photosensitive drum is cleaned by a cleaning device (cleaning means), and after this cleaning, the charge remaining on the photosensitive drum is removed to equalize the potential and prepare for the next process. It has become.

By the way, as the charger, for example, a scorotron charger is used. This scorotron charger can charge the photosensitive drum surface more uniformly than a corotron charger without a grid (control electrode), and this effect is particularly noticeable during negative discharge.

(Problem to be Solved by the Invention) However, since the scorotron charger has a grid to which a voltage is applied close to the surface of the photosensitive drum, toner leaking from the developing device or cleaning device flows along the photosensitive drum. In this case, the grid attracts the toner by attracting the electric charge of the toner.

As described above, when the grid is contaminated with toner, since toner is a dielectric substance, the electric potential on the grid surface appears to be uneven, and the photosensitive drum cannot be charged uniformly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that can uniformly charge an image carrier without causing developer leaked from a developing means or a cleaning means to adhere to a control electrode of a charger. .

[Structure of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention includes an image carrier, a charger that discharges and charges the surface of the image carrier through a control electrode, and a charger that charges the surface of the image carrier by discharging electricity through a control electrode. An electrostatic latent image forming means for forming an electrostatic latent image on the surface of an image carrier charged by a charger, and a developer is supplied to the electrostatic latent image formed by the electrostatic latent image forming means to develop it. a developing means for transferring the developer image developed by the developing means to a transfer material; a cleaning means for removing the developer remaining on the image carrier after the image is transferred by the transferring means; An application means is provided between the charger and the developing means and between the charger and the cleaning means, and applies a voltage of the same polarity as the control electrode of the charger. It is characterized by:

(Function) By causing the developer leaking from the developing means or the cleaning means to adhere to the application means, it is possible to prevent the developer from adhering to the control electrode of the charger.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 2 shows an electronic copying machine, and numeral 1 in the figure is the main body of the copying machine. A photosensitive drum 2 as an image carrier is rotatably provided in the copying machine main body 1, and around the photosensitive drum 2, a scorotron charger 3, an exposure section 4, a plus a developing device (developing means) 5 for supplying charged toner t; a transfer/separation charger 6.
7. Cleaning device (cleaning means) 8 and static eliminator 9
is installed.

Further, a conveyance path 10 is provided at the lower side of the copying machine main body 1, and this conveyance path 10 sequentially includes a paper feed roller 11, a registration roller 12, the transfer and peeling chargers along the conveyance direction of the paper P. 6.7, a conveyor belt 18, and a fixing device 13 are provided.

Further, an exposure lamp (latent image forming means) 22 is provided on the upper side of the copying machine main body 1 to expose an original G set on a movable original platen 21.

Furthermore, a paper feed cassette 1 is provided on one side of the copying machine main body 1.
5 is removably attached, and a paper discharge tray 17 is provided on the other side.

As shown in FIG. 1, the scorotron charging gj13 is formed into a U-shaped cross section, and includes a case 23 whose opening side faces the surface of the photosensitive drum 2, and a high voltage a charging wire 24 to which is applied;
The charging wire 24 is composed of a grid (control electrode) 25 provided between the charging wire 24 and the photosensitive drum 2. A power source 26 is connected to the grid 25, and a negative voltage is applied thereto.

Incidentally, conductive members 31 and 32 are disposed along the photosensitive drum 2 between the scorotron charger 3 and the developing device 5 and between the scorotron charger 3 and the cleaning device 8, respectively. . As shown in FIG.
(not shown) is supported by the copying machine main body 1.

The conductive members 31 and 32 are connected to the grid 2.
It is electrically connected to 5.

During image formation, the exposure lamp 22 irradiates the document G on the traveling document table 21 with light, and the reflected light from the document C forms an image on the surface of the photosensitive drum 2 . The surface of the photosensitive drum 2 is charged by a charger 3, and an electrostatic latent image of the original is formed thereon. This electrostatic latent image is sent to the developing device 5 by the rotation of the photosensitive drum 2, and is developed by supplying toner t from the developing device 5.

On the other hand, at this time, the paper P is taken out from the paper feed cassette 15 by the take-out roller 15a and sent to the registration roller 12 via the paper feed roller 11.

After the paper P is aligned by the registration rollers 12, it is sent between the photosensitive drum 2 and the transfer charger 6.
The image is transferred. The paper P to which this image has been transferred is peeled off from the photosensitive drum 2 by the action of the peeling charger 7. Then, this peeled paper P is sent to the fixing device 13, where the image is fixed, and then the paper is discharged onto the paper discharge tray 17.

Furthermore, the toner t remaining on the photosensitive drum 2 after the image transfer to the paper P is scraped off and removed by the cleaning blade 8a of the cleaning device 8.

After being cleaned in this way, the static eliminator 9
As a result, the charge on the photosensitive drum 2 is removed and the potential is made uniform, in preparation for the next process.

By the way, during image formation, the positively charged toner t leaks out from the developing device 5 and the cleaning device 8, floats around, and tends to adhere to the negatively charged grid 25 of the scorotron charger 3. however,
This floating toner t is attracted to negatively charged conductive members 31 and 32 on the way to the grid 25.

Therefore, the toner t does not adhere to the grid 25, and uneven discharge of the charger 3 can be reliably prevented, and the photosensitive drum 2 can be charged uniformly.

Note that in the above embodiment, the conductive members 31 and 32
is electrically connected to the grid 25, but the present invention is not limited to this, and a voltage may be applied to the conductive members 31 and 32 by a separate power source.

[Effects of the Invention] As explained above, according to the present invention, developer leaking from the developing means or cleaning means does not adhere to the control electrode of the charger, and uneven discharge of the charger can be reliably prevented. This has the effect that the image carrier can be charged uniformly.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a block diagram showing an image forming section, FIG. 2 is a schematic block diagram showing an electronic copying machine, and FIG. 3 is a block diagram showing a conductive member. It is. 2... Image carrier (photosensitive drum), 3... Charger, 5
...Developer (developing means) 6...Transfer device, 8...
Cleaning device (cleaning means), 25...grid (
Control electrode) 31.32... Conductive member (applying means).

Claims (1)

[Claims] An image carrier, a charger that charges the surface of the image carrier by discharging through a control electrode, and an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the image carrier charged by the charger. a developing means for supplying a developer to develop the electrostatic latent image formed by the electrostatic latent image forming means; and a transfer means for transferring the developer image developed by the developing means to a transfer material. and cleaning means for removing developer remaining on the image carrier after image transfer by the transfer device, and at least one location between the charging device and the developing device and between the charging device and the cleaning device. An image forming apparatus comprising: an applying means for applying a voltage of the same polarity as a control electrode of the charger.