JPH04304476A - Image forming device - Google Patents

Abstract

PURPOSE:To attain miniaturization and reduction in cost, and to improve cleaning efficiently by adding the functions of an electrifier and a destaticizer to a cleaning blade. CONSTITUTION:The cleaning blade 3 is made of a conductive material, and simultaneously, an AC voltage A and a DC voltage D which are independently controlled by a control means U, respectively, are communicated with the blade 3. While a photosensitive drum 1 is rotated, the AC voltage A is applied, and in this state, when the blade 3 is positioned at the image forming region of the drum 1, the DC voltage D is applied and the drum 1 is electrified to a prescribed change. When the image forming region passes, the application of the DC voltage is stopped, only the AC voltage A is applied, the drum 1 is discharged and simultaneously, the toner is discharged as well.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus using a photoreceptor (drum) such as a copying machine or a laser beam printer, and more specifically, the present invention relates to an image forming apparatus using a photoreceptor (drum) such as a copying machine or a laser beam printer. The present invention relates to a device for applying a predetermined voltage to a device.

0002

2. Description of the Related Art Generally, an image forming apparatus includes a cleaning device, a pre-static eliminating device, a primary charging device, etc. arranged around a photosensitive drum. The cleaning device has a cleaning blade that comes into sliding contact with the surface of the photosensitive drum.
The blade scrapes off the toner remaining on the drum to clean the drum surface. Further, the pre-static elimination device consists of a pre-exposure lamp or a corona discharger to which an alternating current voltage is applied,
Eliminate the remaining charge on the photosensitive drum. The primary charging device includes a corona discharger to which a predetermined DC voltage is applied, and charges the photosensitive drum with a positive or negative charge. In addition to corona dischargers, there are also contact type devices that use conductive rollers or conductive brushes as electrification/charging devices.

0003

Accordingly, conventional image forming apparatuses include an image exposure device, a developing device, a transfer/separation device, a cleaning device, a pre-static eliminating device, and a primary charging device around the photosensitive drum. This increases the complexity of the device and hinders further miniaturization and cost reduction of the image forming device.

[0004] Furthermore, it is difficult for the cleaning device to sufficiently remove toner that is strongly electrostatically attracted only by the scraping action of the cleaning blade. A pre-cleaning static eliminator such as a corona discharger or an exposure lamp to which a DC voltage of opposite polarity to the toner is applied is installed to weaken the electrostatic adsorption force of toner to the photosensitive drum and improve the efficiency of the cleaning action by the blade. However, installing the static eliminator causes the device to become complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus in which the functions of a charging device and a static eliminating device are added to a cleaning blade, thereby reducing the size and cost as well as improving cleaning efficiency. It is something to do.

[0006]

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned circumstances, and as shown, for example, with reference to FIGS. A blade (3) that scrapes off the toner (2) remaining on the photoconductor
In an image forming apparatus (6) comprising a cleaning device (5) having It is characterized by being provided with a control means (U) which communicates a direct current voltage (D) for body charging and applies these alternating current voltage and direct current voltage independently and appropriately according to the image forming operation. .

[0007]

[Operation] Based on the above configuration, when the control means (U) applies an alternating current voltage (A) with the start of rotation of the photoreceptor (1),
The surface of the photoreceptor (1) is neutralized via the blade (3). In this state, when the image forming area of the photoreceptor (1) reaches the blade (3), the control means (U) applies a predetermined DC voltage (D) to charge the photoreceptor surface with a predetermined charge. do. Then, by exposing the photoreceptor (1)
An electrostatic latent image is formed in the image forming area, and a developing device adsorbs toner (2) onto the surface of the photoreceptor to form a visible image, and the toner image is transferred onto a sheet. At this time, the photoreceptor (
When the image forming area 1) adds the blade (3) portion, the control means (U) stops applying the DC voltage (D),
Only the AC voltage (A) is maintained in the applied state. In this state, the surface of the photoconductor (1) becomes static-free, removing the electrostatic latent image, and the toner (2) is also static-free, leaving the surface of the photoconductor (1) free of charge.
Weakens the adsorption force to. Therefore, the residual toner adhering to the surface of the photoreceptor (1) is easily scraped off by the blade (3) of the cleaning device (5).

[0008]

[Effects of the Invention] As explained above, according to the present invention,
Since the blade (3) of the cleaning device (5) removes and charges the photoreceptor (1), the special charge eliminator and charging device that were conventionally required are not required, and the configuration of the image forming device (6) is simplified. This makes it possible to reduce the size and cost of the device.

[0009] Also, the AC voltage (A) to the blade (3)
By applying , it is possible to weaken the adsorption force of the toner (2), thereby increasing the toner scraping effect by the blade (3) and preventing toner from accumulating on the blade (3) portion, thereby improving the cleaning device. (5) Photoreceptor (1
) can be reliably removed.

[0010] Note that the above reference numerals in parentheses are for contrast with the drawings, but do not limit the structure in any way.

[0011]

[Embodiment] As shown in FIG. 2, a copying machine 6 has a photosensitive drum 1 constituting a photoconductor, and a selfoc lens 7 constituting an exposure device and a developing device are arranged around the photoconductor drum. 8, a transfer charger 9, a separation charger 10, and a cleaning device 5 are provided. Above the SELFOC lens 7, an original platen 11 that is reciprocated with respect to the main body is arranged, and light reflected from a light source 12 by a reflective shade 13 is placed on the glass surface of the original platen 10. The light is reflected by the original document P, guided to the lens 7, and formed into an image on the photosensitive drum 1. Further, a sheet introduction guide 15 extends from a paper feed cassette (not shown) so as to be guided to the transfer charger 9, and a pair of registration rollers 16 are interposed in the guide 15. Further, a conveyor belt 17 extends from the separation charger 10 so as to guide the sheet to a fixing device (not shown).

Further, the photosensitive drum 1 is made of OPC (organic semiconductor), and is driven to rotate in a predetermined rotation direction R at a predetermined timing based on a command from a control section. The developing device 8 has a case 19 containing the toner 2.
Inside, there are a stirring rod 20 for stirring the toner 2, a sleeve 21 for supplying the toner 2 to the photosensitive drum 1, and the sleeve 21.
A blade 22 is disposed thereon to uniformly deposit the toner. On the other hand, the cleaning device 5 has a case 23, and a screw conveyor 2 is installed in the case to convey the waste toner 2 in the case to a waste toner case (not shown).
5 and 26 are housed, and the blade support member 2
7 is rotatably supported.

The blade support member 27 is made of a non-conductive material, has a middle portion supported by a support shaft 29, has a weight 30 fixed to one end, and has a blade presser 31 fixed to the other end with a screw 32. The cleaning blade 3 is attached by being fixed. The cleaning blade 3 is made of an elastic member, and is in sliding contact with the surface of the photosensitive drum 1 based on a weight 30 provided on a support member 27. As the drum 1 rotates, the cleaning blade 3 removes toner 2 adhering to the drum.
may be scraped into the case 23.

As shown in FIG. 1, the blade holder 31 and the blade 3 are made of a conductive material, and are connected to a DC power source D.
and is connected to AC power supply A. Further, these DC power supply D and AC power supply A are connected to a control section (C
PU)U are independently controlled via drivers 35 and 36, respectively, to generate 750 VDC and 1500 Vp AC.
A voltage p is applied (biased) to the photosensitive drum 1 via the blade 3.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 and 4.

When the operator places the document P on the document table 11 and presses the start button from a standby state in which the photosensitive drum 1 is in a stopped state, the photosensitive drum 1 starts rotating (pre-rotation). Simultaneously with the start of the rotation, the control unit U applies a predetermined voltage (1500 Vpp) from the AC power supply A to the blade 3 (AC bias) (S1) to eliminate static electricity from the surface of the photosensitive drum 1. When the area of the photosensitive drum 1 where the image is formed reaches the blade 3, a predetermined voltage (750V) is applied to the blade 3 from the DC power supply D in addition to the AC voltage (DC bias) (S2), and the photosensitive drum 1 -750
Charge V uniformly. In this state, the charged portion of the photosensitive drum 1 is irradiated with reflected light from the original P from the SELFOC lens 7 (image exposure), and an electrostatic latent image is formed on the surface of the drum 1. Then, a developing device 8 is applied to the electrostatic latent image portion.
Toner 2 is adsorbed from the toner to form a visible toner image. On the other hand, transfer paper is being fed from a cassette (not shown) to a pair of registration rollers 16 along a sheet introduction guide 15, and based on a command from a control unit U, the registration rollers are moved in response to the rotation of the photosensitive drum 1. The pair 16 is driven, and the transfer paper is sent to the transfer charger 9 section. The transfer charger 9 transfers the toner image onto the conveyed sheet with the timing adjusted, and the separation charger 10 separates the sheet from the drum 1 and transfers it to the conveyor belt. 17
transported by.

Then, when the above-described image forming area on the photosensitive drum 1 comes off from the blade 3 portion, the control unit U stops applying the DC voltage D (S3), so that only the AC voltage A is applied to the photosensitive drum 1. When the static electricity is removed,
The electrostatic latent image on the photosensitive drum 1 is removed. Furthermore, the photosensitive drum 1 continues to rotate (post-rotation), but in this state, only AC voltage is applied to the blade 3 (AC bias), and at the same time as the photosensitive drum 1 is neutralized, the toner 2 itself is The electrostatic adsorption force is also reduced, and the toner remaining on the surface of the drum 1 is easily and reliably scraped off by the blade 3. When the post-rotation of the photosensitive drum 1 is also stopped, the control unit U also stops applying the AC voltage A (AC bias) (S4) and returns to the standby state again.

Next, a partially modified embodiment will be described with reference to FIGS. 5 and 6. In this embodiment, the same parts as in the previous embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, a pre-cleaner exposure lamp 40 is attached in front of the cleaning device 5. The pre-exposure lamp 40 is turned on when the photosensitive drum 1 is rotating, similar to the application of AC voltage (bias) by the blade 3.

Due to the exposure by the pre-cleaner exposure lamp 40, the potential of the entire surface of the photosensitive drum 1 is lowered, and the transfer and
This helps remove the charge remaining on the photosensitive drum 1 after separation, thereby ensuring the removal of the electrostatic latent image on the photosensitive drum 1 based on the application of an alternating current voltage (AC bias) to the blade 3, and the toner 2 itself. The electrostatic adsorption force of the blade 3 is weakened to ensure that the toner is scraped off by the blade 3.

FIG. 7 is a diagram showing a further modified embodiment. In the previous embodiment, the cleaning blade 3 was installed in opposition to the rotational direction of the photosensitive drum. This embodiment is different in that it employs a forward method in which the blade 3 is in contact with the photosensitive drum in the forward direction relative to the rotational direction of the photosensitive drum.

That is, the cleaning blade 3 is attached to the support shaft 2.
Blade support member 2 rotatably supported by 9
A spring 41 is attached to the tip of the support member 27 at an angle in the rotational direction R of the photosensitive drum 1, and a spring 41 is attached to the other end of the support member 27.
is stretched to urge the tip of the blade 3 into contact with the surface of the drum 1. Further, as in the previous embodiment, the blade 3 is made of a conductive material, and is connected to a DC power source D and an AC power source A, each of which is independently controlled by a control section.

In the above-described embodiment, it is also conceivable to apply only a DC voltage to the cleaning blade 3 to perform only primary charging on the photosensitive drum. In this case, the application of the DC voltage is maintained in an applied state (DC bias) while the photosensitive drum 1 is rotating, and is maintained in a primary charging state, or a pre-exposure lamp is attached, as in the above embodiment. Similarly, DC bias is applied only when the image forming area is located in the blade 3 portion to perform primary charging.

[0024]Although the above embodiment has been described with respect to a copying machine, the present invention is not limited to this, and a laser beam printer, etc.
It goes without saying that the present invention can be similarly applied to other image forming apparatuses using photoreceptors and cleaning blades.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a cleaning blade portion which is the main part of the present invention.

FIG. 2 is a schematic side view showing an image forming part of a copying machine using the blade.

FIG. 3 is a time chart showing the operating status of each component.

FIG. 4 is a flowchart.

FIG. 5 is a schematic side view showing another embodiment.

[Fig. 6] Its time chart.

FIG. 7 is a sectional view showing a partially modified cleaning blade.

[Explanation of symbols]

1 Photoconductor (drum) 2 Toner 3 (cleaning) blade 5
Cleaning device 6 Image forming device (copying machine) A
AC voltage (power supply) D DC voltage (power supply)

Claims (1)

[Claims] 1. An image forming apparatus comprising a cleaning device having a blade that comes into sliding contact with the surface of a photoreceptor to scrape off toner remaining on the photoreceptor, wherein the blade is made of a conductive material. At the same time, on the blade,
A control means is provided for communicating an alternating current voltage for removing static electricity from the photoreceptor and a direct current voltage for charging the photoreceptor, and for applying these alternating current voltage and direct current voltage independently and appropriately in accordance with the image forming operation. Features of the image forming device.