JPH03101785A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a transfer material, a developing device, an electrifying device, etc., from being soiled by bringing the contact point of a scraper sheet with an image carrier downstream of an image carrier rotating direction, viewed from the vertex of the image carrier. CONSTITUTION:The scraper sheet 5 is brought into contact with the photosensitive drum 1 downstream of the photosensitive drum rotating direction, viewed from the vertex (b) thereof. Consequently, cohesive toner, paper dust, etc., pooling in front of the scraper sheet 5 do not fall down along the photosensitive drum 1, but are ground finely by the rotation of the photosensitive drum 1 or its butting against the scraper sheet 5. Then, they pass through the gap between the scraper sheet 5 and the photosensitive drum 1, enter a waste toner recovery chamber 3 where they are collected. Consequently, the soil of the transfer material, developing device, electrifying device, etc., which is caused by the drop of cohesive toner and paper dust pooling on the image carrier 1 therealong, is prevented and a satisfactory image is obtained stably all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, or an electrostatic recording apparatus.

(Prior Art) FIG. 7 shows a cross section of the main parts of an electrophotographic copying machine, in which a photosensitive tram 1 as an image carrier is used.
A toner image is formed on the photosensitive drum 1 through known processes such as charging, exposure, and development, and this toner image is transferred onto the transfer paper S by the transfer roller l3. At this time, the waste toner T remaining on the photosensitive drum 1 without being transferred onto the transfer paper S is scraped off by the cleaning blade 4 of the cleaning device 2 and collected into the waste toner storage chamber 3.

By the way, the photosensitive tram 1 includes a cleaning blade 4.
A scooping sheet 5 is brought into sliding contact with the waste toner T scraped off by the toner storage chamber 3 to hold it in the toner storage chamber 3. As shown in the figure, this scooping sheet 5 is positioned further away from the apex b of the photosensitive drum 1 in the rotational direction of the photosensitive drum 1. It was in contact with the photosensitive drum 1 on the upstream side (in the direction of arrow a in the figure).

(Problem B to be solved by the invention) However, if the contact position of the pick sheet 5 with the photosensitive drum 1 is located upstream of the apex b of the photosensitive tram l in the rotational direction of the photosensitive drum as described above, the agglomerated toner Agent S
The paper powder etc. that have separated from the paper are blocked from passing by the scoop sheet 5,
Problems arise in that these particles roll down along the photosensitive drum 1, staining the transfer agent S, staining the developing device and charging device (not shown), and disturbing the image. In particular, when the photosensitive drum 1 rotates quickly and its circumferential speed is high, the amount of agglomerated toner X, paper dust, etc. that remains on the pick-up sheet 5 is large per unit time, and the above problem becomes significant.

The present invention has been made in view of the above-mentioned problems, and its object is to cover a transfer material, a developing device, a charging device, etc. caused by the falling of aggregated toner and paper dust remaining on an image bearing member along the image bearing member, etc. It is an object of the present invention to provide an image forming apparatus that can prevent stains on the image forming apparatus and constantly and stably obtain good images. (Means for Solving the Problems) In order to achieve the above object, the present invention includes an image carrier that rotates at a circumferential speed of 20 cm/sec or more, and an image carrier that is disposed above the image carrier and that slides on the image carrier. In an image forming apparatus including a certain cleaning device having a cleaning member and a pick sheet in contact with each other, the point of contact of the pick sheet with the image carrier is set at a point in the rotational direction of the image carrier rather than an apex of the image carrier. Its distinctive feature is that it is located on the downstream side. (Function) According to the present invention, aggregated toner, paper powder, etc. that remain on the pick sheet on the image carrier are prevented from rolling down along the image carrier, and are broken down into small pieces and pass through the pick sheet, so that transfer is possible. This eliminates dirt on the material, developing device, charging device, etc., and allows you to consistently obtain good images. (Example) Examples of the present invention will be described below based on the attached drawings. FIG. 1 is a vertical cross-sectional view of the main part of an image forming apparatus showing a first embodiment of the present invention, in which l represents a photosensitive drum as an image bearing member, which is positioned in a predetermined direction in the direction of arrow a in the figure. Rotationally driven at speed. A cleaning device 2 is disposed above the photosensitive drum 1. Although not shown, in addition to the cleaning device 2, process means such as a charging device, an exposure device, a developing device, and a transfer device are arranged around the photosensitive tram 1 to form an image according to a known image forming process. will be done. Incidentally, the cleaning device 2 has a waste toner storage chamber 3 and a cleaning blade 4 and a scraping sheet 5 as cleaning members, and the cleaning member 4 and the scraping sheet 5 are in sliding contact with the photosensitive tram 1.

In the cleaning device W2, the residual toner T adhering to the photosensitive drum 1 is scraped off by the cleaning blade 4 and stored in the waste toner storage chamber 3. The point of contact with the photosensitive drum 1 is located downstream of the apex b of the photosensitive drum 1 in the rotational direction (in the direction of arrow a in the figure). )
, urethane sheet, etc. are used.

Incidentally, normally, the residual toner T adhering to the photosensitive tram 1 moves toward the cleaning device 2 as the photosensitive drum 1 rotates, passes between the scraper sheet 5 and the photosensitive tram 1, and is scraped off by the cleaning blade 4. taken. This scraped waste toner T is then stored in the waste toner storage chamber 3.
accumulated within. At this time, the scooping sheet 5 serves to prevent the waste toner T from blowing out from the waste toner storage chamber 3. However, aggregated toner, coarse toner, or large pieces of paper dust coming from the transfer material remain in front of the pick sheet 5. However, in this embodiment, as described above, since the pick sheet 5 is in contact with the photosensitive tram l on the downstream side of the apex b in the rotational direction of the photosensitive tram, the agglomerated toner, paper powder, etc. remaining in front of the pick sheet 5 are removed. They do not roll down along the photosensitive drum 1, but are finely pulverized by the rotation of the photosensitive drum 1 and collision with the pick sheet 5, and eventually pass between the pick sheet 5 and the photosensitive drum 1 and enter the waste toner storage chamber 3. It enters and is collected. As mentioned above, since aggregated toner, paper powder, etc. are prevented from falling along the photosensitive drum 1, the problem of contamination of the transfer material, developing device, charging device, etc. is solved, and good images are always stably obtained. You will be able to do it.

Table 1 shows experimental results regarding the relationship between the circumferential speed of the photosensitive drum l and image stains in comparison with a conventional example (shown in FIG. 7).

Note that the contact points of the scraping sheet 5 in this embodiment and the conventional example are the contact points of the photosensitive drum 1 as shown in FIG.
The angles shown in the figure are on the downstream and upstream sides of the photosensitive drum rotation direction from the apex b (the angle between the straight line connecting the center 0 of the photosensitive drum l and the apex b, and the straight line connecting the center 0 and the contact point of the pick sheet 5). It is located at a position where α, = 8°, β = 3″.
In the experiment, a uniform black solid image was formed using 1-component toner by jumping development, and the condition of the image was examined on iooo sheets of transfer paper. In Table 1, ○ indicates that there is no image stain at all;
× indicates a state of severe image staining, and Δ indicates a state intermediate between O and × in which some image staining is observed.

Table 1 As is clear from Table 1 above, in the conventional example, image stains occur when the circumferential speed of the photosensitive drum 1 exceeds 20 amlsec, but in the wooden embodiment, the entire circumferential speed of the photosensitive drum 1 increases. No image stains occurred throughout.

Next, modified embodiments of the present invention are shown in Figs. 2 to 6, respectively. In the embodiment shown in FIG. 2, the squeegee 5 is brought into contact with the photosensitive drum 1 not against the edge but against the surface. If the squeeze 5 is made of a soft material such as urethane sheet and is placed against the belly as shown, the photosensitive drum 1 can be protected from scratches. In this embodiment as well, since the contact point of the scraping sheet 5 is located downstream of the apex b of the photosensitive drum 1 in the rotational direction of the photosensitive drum, the same result as that obtained in the first embodiment is obtained. You can get the effect. Note that the illustrated angle α2 is set to O″<α2≦45°.

Further, in the embodiment shown in FIG. 3, a cleaning plate 8 with a back plate 9 is provided, and waste toner is stored on the right side of the figure. In this embodiment as well, since the contact point of the scraping sheet 5 is located downstream of the apex b of the photosensitive drum l in the rotational direction of the photosensitive drum, the same result as that obtained in the first embodiment is obtained. You can get the effect. Note that the illustrated angle α3 is set to O0<α3≦45°. FIG. 4 shows an example in which a 10-ft silicone rubber roller is provided between the cleaning blade 4 and the scraper sheet 5, which is driven in contact with the photosensitive drum 1. By polishing the surface of the photosensitive drum 1 with this roller 10, an image can be imaged. Disturbance can be prevented. That is, when the photosensitive drum 1 is made of an organic semiconductor, ozone is generated from a charging device (not shown), and nitrogen oxides are deposited on the photosensitive drum 1 due to the ozone. Disturbances occur in the image because the upper charge flows. Therefore, if nitrogen oxides deposited on the photosensitive drum 1 are removed by polishing using a silicone rubber roller 10, image distortion can be prevented. In this embodiment as well, since the contact point of the scraping sheet 5 is located downstream of the apex b of the photosensitive drum 1 in the rotational direction of the photosensitive drum, the same result as that obtained in the first embodiment is obtained. You can get the effect. Note that the angle α4 shown in the figure is set to O0<α4≦45°, and FIG. 5 shows the angle α4 shown in FIG.
An example in which a magnet roller 10' is provided instead of O is shown. This magnet roller 10' is not in contact with the photosensitive tram 1, and when magnetic toner is used as a developer, waste toner adheres to the magnet roller 10'.
This waste toner comes into contact with the photosensitive drum 1 and
Since the surface is polished, it is possible to prevent image distortion for the same reason as mentioned above.

In this embodiment as well, since the contact point of the cutting sheet 5 is located downstream of the apex b of the photosensitive drum l in the rotational direction of the photosensitive drum, the same result as that obtained in the first embodiment is obtained. You can get the effect. The illustrated angle α5 is set to O''<α5≦45°. Furthermore, in the embodiment shown in FIG. 6, a cleaning brush l1 and a brush removal rod l are used instead of the cleaning blade.
2 are provided. In this case, the waste toner particles that have passed through the scraper sheet 5 are removed by the rotating cleaning brush 1l, and the waste toner particles that have adhered to the cleaning brush l1 are removed by the rotating cleaning brush 1l.
is removed by brush removal rod l2. In this embodiment as well, since the contact point of the cutting sheet 5 is located downstream of the apex b of the photosensitive drum l in the rotational direction of the photosensitive drum, the same result as that obtained in the first embodiment is obtained. You can get some effect. Note that the angle α6 shown in the figure is O''
It is set to 〈α6≦45゜. (Effect of the invention) As is clear from the above explanation, according to the present invention, the peripheral speed is 20
(2) An image forming system comprising an image carrier that rotates at a speed of 1/sec or more, and a cleaning device having a cleaning sheet and a cleaning member disposed above the image carrier and in sliding contact with the image carrier. In the apparatus, since the point of contact of the scraping sheet with the image carrier is located downstream of the apex of the image carrier in the rotational direction of the image carrier, image carriers such as agglomerated toner and paper powder that remain on the image carrier are prevented. This prevents the transfer material, developing device, charging device, etc. from becoming dirty due to falling along the body, and good images can always be stably obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the main part of an image forming apparatus showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the main part of an image forming apparatus showing a second embodiment of the invention, and FIG. FIG. 4 is a vertical cross-sectional view of a main part of an image forming apparatus showing a third embodiment of the present invention, and FIG.
FIG. 5 is a vertical sectional view of the main part of an image forming apparatus showing a fifth embodiment of the present invention; FIG.
FIG. 6 is a vertical cross-sectional view of the main part of an image forming apparatus W showing a sixth embodiment of the present invention, and FIG. 7 is a vertical cross-sectional view of the main part of a conventional image forming apparatus. DESCRIPTION OF SYMBOLS 1... Photosensitive drum (image carrier), 2... Cleaning device, 4... Cleaning blade (cleaning member), 5... Screw sheet, b... Vertex of photosensitive tram.

Claims (1)

[Claims] An image forming system that includes an image carrier that rotates at a peripheral speed of 20 mm/sec or more, and a cleaning device that includes a cleaning member that is placed above the image carrier and comes into sliding contact with the image carrier, and a scoop sheet. An image forming apparatus characterized in that a point of contact of the scraping sheet with the image carrier is located downstream of a vertex of the image carrier in the rotational direction of the image carrier.