JPH02148084A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce damage to a photosensitive body owing to paper dust, etc., by supplying a proper place of the surface of the photosensitive body with toner irrespective of picture information, in an image forming device provided with an elastic blade which removes toner remaining on the photosensitive body after transfer. CONSTITUTION:Toner is supplied to the areas P1 and P2 on the surface of the photosensitive body of a rotating drum 8 based on picture information from a computer; however, toner is also supplied to areas T1 and T2 virtually irrespective of picture information. The lateral length W is the same as the longitudinal length of the elastic blade 26 which removes and recovers toner remaining on the drum 8 after transfer, or is slightly shorter and the length L in a moving direction is in a range of 1-5mm. Although toner images in the areas P1 and P2 are transferred to a sheet member such as a recording paper, the toner in the areas T1 and T2 acts as lubricant between the drum 8 and the blade 26, thereby preventing the surface of the photosensitive body from being damaged by paper dust, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image forming apparatus, more specifically, to a photoreceptor surface G.
The present invention relates to an image forming apparatus equipped with an elastic blade for removing residual I/toner.

[Prior art and its drawbacks]

An image forming apparatus such as an electrostatic copying device or a laser beam printer includes an image bearing means such as a rotating drum having a photoreceptor on its surface, and a developing device that develops an electrostatic latent image formed on the surface of the photoreceptor into a toner image. , is equipped with a cleaning device for removing toner remaining on the surface of the photoreceptor after transfer. and,
2. Description of the Related Art Cleaning devices equipped with elastic blades are widely used because they have features such as simple construction.

However, when using an elastic blade, there are the following problems to be solved. Generally, when transferring a toner image, a sheet member such as a recording paper is brought into close contact with the surface of an image bearing means. Therefore, during this close contact, paper dust, etc. from the sheet member tends to adhere to the surface of the image carrying means, and the paper dust, etc. that adheres to the surface G (=j) is removed by the elastic blade during cleaning, and the free end of the elastic blade Therefore, when a certain amount of residual l.ner exists between the elastic plate and the image bearing means,
This residual l/toner acts as a lubricant, and the photoreceptor is not scratched by paper dust or the like. On the other hand, if there are continuous non-adhesive areas (areas that do not appear as an image on the recording paper) where toner is not applied, the amount of residual I/toner described above decreases, and this causes paper dust, etc. to act directly on the photoreceptor surface. Thus, the paper dust etc. cause scratches on the photoreceptor.The adhesion of paper dust etc. to the surface of the image bearing means is caused by so-called reversal development (-4 area where the toner adheres and where the toner adheres). Charges of the same polarity exist in the non-adhesive non-blue area, and the l-space has the same polarity as the black area, etc., and the absolute value of the potential is smaller than the non-adhesive area. This problem is particularly likely to occur when a developing method (in which the above-mentioned L/ner is applied to the area) is used, and therefore, damage to the photoreceptor is also likely to occur.

[Purpose of the invention]

The present invention has been made in view of the above facts, and its main purpose is to provide an excellent image forming apparatus that can reduce damage to a photoreceptor due to paper dust and the like.

[Summary of the invention]

According to the present invention, an image bearing means having a photoreceptor on its surface;
In an image forming apparatus that includes a developing device that develops an electrostatic latent image formed on the surface of the photoreceptor into a toner image, and an elastic blade that removes the toner remaining on the surface of the photoreceptor after the transfer, substantially no information is added to the image information. There is provided an image forming apparatus characterized in that 1 hener is supplied to the surface of the photoreceptor by the action of the developing device.

[Specific examples of the invention]

Hereinafter, a specific example of an image forming apparatus according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1, which shows a laser beam printer as an example of an image forming apparatus, the illustrated laser beam printer is equipped with a device housing 2 having a substantially rectangular parallelepiped shape, and a number 4 is designated as a whole in the approximate center of the device housing 2. The process unit shown is installed. Process unit 4 shown
has a unit frame 6, and a rotary drum 8 constituting an image carrying means is rotatably mounted on the unit frame 6.

An electrostatic photoreceptor is disposed on the circumferential surface of the rotating drum 8. A charging corona discharger 12 and a developing device 1 are arranged around the rotating drum 8 which is rotated in the direction shown by the arrow 10.
4. Transfer corona discharger 16 and cleaning device W18
A charging corona discharger 12, a developing device 14, and a cleaning device 18 are mounted on the unit frame 6.

A charging unit L1 discharger 12 charges the photoreceptor on the rotating drum 8 to a specific polarity. The developing device 14 is a hollow sleeve 2
0 and the permanent magnet 2 disposed within this hollow sleeve 20
The developer held by the magnetic brush mechanism 24 is supplied to the surface of the rotating drum 8. Although this developing device W14 is of a reverse development type in the specific example, it may be of a normal rotation development type. The transfer corona discharger 16 applies corona discharge to the back surface of the sheet member being conveyed through the conveyance path, as will be described later. The cleaning device 18 includes an elastic blade 26 that acts on the surface of the photoreceptor, removes toner remaining on the surface of the photoreceptor, and collects the toner in a toner collection chamber 28 .

Optical means 30 is disposed in the upper part of the device housing 2, that is, above the process unit 4.

The optical means 30 includes a laser light source 32 (FIG. 2), a rotating polygon mirror 34 rotated in a predetermined direction, a so-called fθ lens 36, and a first
, a second reflecting mirror 40 and a cylindrical lens 42. The laser light source 32 irradiates the rotating polygon mirror 34 with a laser beam that has been used for image information outputted from, for example, a combination unit 1-1. The laser beam reflected from the rotating polygon mirror 34 is reflected as shown by the dashed line arrow in FIG.
, 1θ lens 36 to the first reflecting mirror 38, and this first reflection! After being reflected by the 1-1 mirror 3B and the second reflecting mirror 40, it passes through the cylindrical lens 42 and is projected onto the surface of the rotating iron drum 8 at a projection area 446.

At the lower part of the device housing 2, that is, below the process unit 4, a transport mechanism designated by numeral 46 is disposed.

The arrangement mechanism 46 defines a conveyance path for conveying a sheet member such as a recording paper through a transfer area 48, and a pair of registration rollers 5.
6, a guide plate 52, a guide plate 54, and a pair of fixing rollers 56. In the specific example, the upstream end of the conveyance path is branched into two, one of which extends straight to the right in FIG. 1, and a manual feeding means 58 is disposed at the upstream end. The other end is curved and extends downward, and its upstream end (
Specifically, an automatic supply means 60 is disposed below the transport mechanism 46. The illustrated manual supply means 58 includes a table 62 that is pivotable between the supply position shown in FIG. table 62
is positioned at the supply position. When the sheet member is positioned on the table 62-hi and inserted through the opening 64,
Such a sheet member includes the f-plane of the guide piece 66 and the guide protrusion 6B.
The rollers are guided to a pair of registration rollers 50 by passing between the upper edges of the rollers. Further, the illustrated automatic supply means 60 includes a cassette 70 into which sheet members are loaded in a stacked state. The cassette 70 is removably attached to a cassette receiving portion 74 defined at the bottom of the device housing 2 through the opening lower 2 . A feeding roller 76 is provided above the cassette receiving portion 74.
is installed. Therefore, the feed roller 76 is
By being rotated in the direction indicated by , the sheet members in the cassette 70 are delivered every month, and the thus delivered sheet members are guided by the guide protrusion 82 provided on the upright wall portion 8o and the guide protrusion 68. and is guided to a pair of registration rollers 50.

Further, the downstream end of the conveyance path is also branched into two, and in connection with this, a part of the device housing 2, that is, a rectangular opening/closing portion 84 on the left side in FIG. It is possible to select a first position shown by a chain double-dashed line and a second position shown by a solid line in FIG. Opening/closing part 84
is in the first position, the sheet member delivered from the first pair of discharge rollers 86 is directly delivered to the device housing 2.
It is discharged to the outside and is received by the inner surface (the upper surface in the state shown by the two-dot chain line) of the opening/closing portion 84 described in (b). On the other hand, when the opening/closing section 84 is in the second position, the sheet member sent out from the first pair of discharge rollers 86 passes between the opening/closing section 84 and a part 88 of the device housing 2 and moves further upward. and is discharged to a receiving portion 92 defined on the inclined upper surface of the device housing 2 by the action of the second pair of discharge rollers 90 . Further, an auxiliary member 94 is attached to the upper end of the receiving portion 92 so as to be pivotable between a receiving position shown by a solid line in FIG. 1 and a storage position shown by a two-dot chain line in FIG.

The operation of the laser beam printer described above is summarized as follows.

While the rotating drum 8 is rotated in the direction not shown by the arrow 10, the charging corona discharger 12 charges the photoreceptor of the rotating drum 8, and then the image from the laser light source 32 of the optical means 30 is projected in the projection area 44. Laser light carrying information is projected onto the photoreceptor, thus forming an electrostatic latent image corresponding to the image information on the surface of the photoreceptor. Thereafter, the electrostatic latent image is developed into a toner image by the action of the developing device 14. Next, the sheet member supplied to the conveying path from the manual supply means 58 or the automatic supply means 60 is brought into contact with the photoreceptor in the transfer area 48, and the toner image on the photoreceptor is transferred to the sheet by the action of the transfer corona discharger 16. transferred to the member. The sheet member onto which the toner image has been transferred is peeled off from the rotating drum 8 and then conveyed to a pair of fixing rollers 56, where the toner image is fixed on the surface of the sorting member by the action of the pair of fixing rollers 56.

The sheet member with the toner image fixed thereon is conveyed to a first pair of discharge rollers 86, and when the opening/closing section 84 is in the first position, it is discharged onto the opening/closing section 84 as it is. On the other hand, when the opening/closing section 84 is in the second position, the sheet member conveyed to the first pair of discharge rollers 86 is further conveyed upward and then transferred to the second pair of discharge rollers 9.
0 is discharged to the receiving portion 92 of the device housing 2''.

On the other hand, the rotating drum 8 continues to rotate, and the residual toner is removed from the surface of the photoreceptor by the action of the cleaning device 18.

In such an image forming apparatus, some toner is supplied before a toner image corresponding to image information. The image forming apparatus includes a control means 96, which may be constituted by a microprocessor, for example, and the operation of the laser light source 32, the feeding roller 76, and the pair of registration rollers 50 is controlled by signals from the control means 96 as described later. .

Further, a sheet member detection means 98 is arranged downstream of the registration roller 50, and a signal from the detection means 98 is sent to the control means 96. This control means 96 includes timer means 100 for measuring time.

The control by the control means 96 is as follows.

Mainly referring to FIGS. 1 and 3, feeding is carried out by a manual feeder, but when using the automatic feeding means 60, the tip is fed by energizing the feeding roller 76. When a paper feed signal from a computer (not shown) is sent to the control means 96 while the paper is nipped between the pair of registration rollers 50, step n-1
Then, the pair of registration rollers 50 is biased (such biasing is achieved by the clutch means provided on one side of the pair of registration rollers 50 being in a continuous state). Then, feeding of the sheet member nipped by the pair of registration rollers 50 is started, and the sheet member is transported toward the transfer area 48. Next, the process proceeds to step n-'l, where the timer means 100 of the control means 96 is cleared. Then, in the next step n-3, the timer means 100 is turned on and starts counting time. When this timer means lOO is turned on, the control means 96 generates a laser activation signal substantially independent of the image information from the computer, based on which the laser light source 32 is energized and the optical means 30
The rotating polygon mirror 34 is also rotated. Therefore, the rotating drum 8
Light from the laser light source 32 is projected onto the surface to which electric charge has been applied, and the electric charge at the projected site is made to disappear. The laser light source 32 is energized until the timer means 100 measures a predetermined period of time (for example, about 40 meters and 5 seconds) and the time is up. When the time is up, the process proceeds from step n-5 to step n-6 and the timer means 100 is turned off. Then, in step n-7, the laser light source 32 is deenergized. The laser light source 32 (=1) ends before the leading end of the sheet member reaches the detecting means 98, and when the leading end is conveyed to the detecting means 98, the process proceeds from step n-8 to step n-9. In step n-9, image information from the computer is accepted based on the signal from the detection means 98, and the image generation process described in -L is performed based on the image information.

When the above operations are carried out, an I-ner is applied to the surface of the photoreceptor of the rotating drum 8, as shown in FIG. That is, the areas TI and T2 are adhesion areas to which toner is applied substantially regardless of image information, and toner is applied to substantially the entire area of the adhesion areas T1 and T2. The lateral lengths W of the regions T and T2 may be substantially larger than the length of the elastic blade 26 in the longitudinal direction, or may be somewhat smaller than the length of the elastic blade 26 in the longitudinal direction, and The length I7 in the moving direction may be about 1 to 5III1++, preferably about 2 to 311. It should be noted that if the length I5 of the photoreceptor in the moving direction is made thicker (this will result in wasted toner consumption), on the other hand, if the length is made smaller, the desired effect will not be achieved (also, the area P , and P2 are adhesion areas to which toner is applied based on image information from a computer, and the toner applied to these areas P1 and P2 is transferred to a sheet member such as a recording paper as a l.toner image.

In the laser beam printer described above, some toner is applied to the area P where the toner image is formed, and before P2, substantially independent of the image information, so that such toner rotates with the free end of the elastic blade 2G. Elastic blade 2 between drum 8
6 over substantially the entire length thereof. Therefore, the interposed toner acts as a lubricant between the two, preventing paper dust or the like or the elastic blade 26 from directly acting on the surface of the photoreceptor, effectively preventing damage to the photoreceptor.

In the specific example, each time the image forming process is performed, toner is applied to the upstream side of the areas P+ and P2 where a toner image is formed, but instead of the upstream side, the toner is applied to the downstream side of those areas A toner may be applied to the side. Note that when the toner is applied to the downstream side, the toner is not applied to the first sheet member as required, which causes scratches on the photoreceptor.

Further, in the specific example, toner is applied over substantially the entire length of the elastic blade 26 in each image forming process, but in order to reduce toner consumption, toner is applied a predetermined number of times (for example, 5 or 10 times). ) A toner may be added to the strawberries. Alternatively, the toner may be applied over substantially the entire width of a sheet member one size smaller than the largest size sheet member used. Paper dust, etc. is most present in particular at both ends of the sheet member, and paper dust, etc. adheres to the surface of the photoreceptor in areas where these both ends come into close contact, but the image on the photoreceptor is substantially In the area where toner is not formed, there is virtually no problem with the adhesion of paper dust, etc., so it is sufficient to apply toner to substantially the entire width of a sheet member one size smaller than the largest sheet member used. effect is achieved.

Although the embodiment of the image forming apparatus according to the present invention has been described above, the present invention is not limited to such a specific example, and various modifications and modifications can be made without departing from the scope of the present invention.

For example, in the illustrated specific example, the description has been made with reference to a type of reversal development; I, which has a polarity opposite to the polarity of the charge in the area, etc., and has a larger absolute value of voltage than the toner-free area.
・Development method in which the above toner is attached to the Qi 41 area)
It can be similarly applied to a form in which this is carried out. In such a case, a charging corona discharger may be energized corresponding to the area to which toner is to be applied, and the charge may be applied by the charging corona discharger.

[Brief explanation of the drawing]

FIG. 1 is a simplified sectional view showing a specific example of a laser beam printer as an example of an image forming apparatus according to the present invention. FIG. 2 is a simplified diagram showing part of the control system in the laser beam printer of FIG. 1. FIG. 3 is a flowchart showing part of the control by the control system of FIG. 2. FIG. 4 is a simplified diagram showing the relationship between the toner applied to the surface of the photoreceptor of the rotating drum in the laser beam printer of FIG. 1 and the toner image formed on the surface, with the rotating drum developed. 8...Rotating drum 14...Developing device 18...Cleaning device 26...Elastic blade 96...Control means T and Tz...Area P to which toner is applied and P
2...Area where a toner image is formed 1.48084 (9
)

Claims (1)

[Scope of Claims] 1. An image carrying means having a photoreceptor on its surface, a developing device for developing an electrostatic latent image formed on the surface of the photoreceptor into a toner image, and a toner image that remains on the surface of the photoreceptor after transfer. An image forming apparatus comprising an elastic blade for removing toner, characterized in that the toner is supplied to the surface of the photoreceptor by the action of the developing device, substantially regardless of image information.