JPS604971A - Electrostatic copying machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to an electrostatic copying apparatus that uses an endless belt photoreceptor and requires that the belt photoreceptor be flat in a portion of its conveyance path.

Conventional technology Exposure in electrostatic copying devices is generally performed by scanning a document through a slit and forming an image on a moving photoreceptor at a fixed point in space. Since the speed had to be the same as the linear speed of the photoreceptor, there was a limit to how high the speed could be increased due to the electrostatic copying process.

However, for example, in the exposure optical system as shown in Figure 1,
A document 0 placed stationary on a contact glass 1 is moved from one end A to the other end B by a distance 4 with all light sources 2 at a constant speed.
By moving the through lens 3 placed at an appropriate position at an appropriate speed, the image formation position can be fixed at a fixed point in space (
It is possible to move a distance of 4 from A/ to B' at a constant speed.

Therefore, if the photoreceptor 13 is made into an endless belt and moved in the opposite direction to the image movement direction, the movement speed of the photoreceptor can be reduced by the image movement speed.

For example, if the moving distance 4 of the image forming position is set to % of the scanning length t1, the linear speed can be set to % of the original scanning speed, making it easy to achieve high-speed copying. It will be reduced. (This is because the point on the photoreceptor at ``only needs to move to A' while the scanner returns, and the blank area on the photoreceptor decreases.'') However, in that case, during the exposure and imaging position movement range t2. In this case, it is necessary for the photoreceptor bell 1-13 to move while maintaining a perfect plane.

As mentioned above, in the conveyance path of the endless belt photoreceptor, a device for maintaining the flatness of the belt photoreceptor is provided in the parts where the belt photoreceptor requires flatness to eliminate belt vibration during traveling.
The back side of the belt photoreceptor is brought into close contact with this device as it is moved to eliminate any ``swells'' on the surface of the belt photoreceptor and to obtain a sufficiently smooth surface.

Of course, it is easy to attach and remove the belt. The requirement is that it can be done easily without any hindrance.

As such a device, a device is known in which a vacuum box having a flat wall portion with many holes is installed so that that portion comes into contact with the back surface of the belt photoreceptor. It is necessary to install a vacuum system on the tower, and the vacuum system is not very preferable because it produces noisy intake/exhaust noise and increases costs.

OBJECTS It is an object of the present invention to provide an electrostatic copying apparatus equipped with a flatness maintaining device that satisfies the above requirements and eliminates the above-mentioned drawbacks of conventional flatness maintaining devices for endless belt photoreceptors.

Configuration The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 2 is a diagram showing an embodiment in which the present invention is applied to a high-speed electrostatic copying machine using a flexible endless belt photoreceptor.

The exposure optical system of this apparatus is the same as the exposure optical system previously explained with reference to FIG.
The image is formed on the exposed portion of the transport path, and the image point moves within a length of 4 at a speed corresponding to the scanning range of the original on the contact glass l/(total scanning speed).

As shown schematically in cross section in FIG. 3, the endless belt photoreceptor 13 is coated with a polyester film 13aK1, a metal conductive material layer 13bi, and a highly sensitive organic conductive layer la.
It is constructed by laminating c. This belt photoreceptor 13 includes a driving roller 9 and a driven roller 10 having a rubber layer on the surface.
, 11 and 12 are in a tensioned state, and can rotate counterclockwise as shown by the arrow. This tension state can be achieved by using the driven roller 12 as a tension roller.

Along the conveyance path of the endless belt photoreceptor 13, there is a charger 14 with a driven roller io on the upstream side of the exposure section, and a developing device 15 with a drive roller 9 on the downstream side.
, a transfer charger 19, and a cleaning device 18 are provided. The optical image of the document exposed on the photoreceptor 13 in the exposure section forms an electrostatic latent image by a known electrostatic photographic process.
It is developed by the developing device 15 to form a toner image.

This toner image is transferred by a transfer charger 19 onto a transfer paper fed from a registration roller 17, and the transfer paper on which the l-toner image has been transferred is fixed by a fixing device 16 and placed on a paper output tray outside the machine. The copy is completed after being ejected. Note that reference numerals 20 and 21 in FIG. 2 are slide guides for removing and removing the belt photoreceptor.

Now, as shown in detail in FIGS. 4 and 5, between the driven roller 1O and the driving roller 9, there is a flatness maintaining member that comes into contact with the back surface of the belt photoreceptor 13 that is conveying the exposure section having a length of 4. 8
is provided. The plane maintaining member 8 is made of a conductive material such as aluminum so that the surface that contacts the photoreceptor is perfectly flat and has sufficient rigidity so as not to be deformed by external force. The plane of the flat surface maintaining member 8 that comes into contact with the belt photoreceptor 13 is set by a number 1111 from the common tangent of the drive roller 9 and the driven roller IO so that the belt photoreceptor 13 does not float.
11 (about 1 to 2 songs) outside. In addition, the front and rear edges of the flat surface maintaining member 8 in the belt photoreceptor conveying direction are as follows:
A static eliminator 7 and a charging device 6 are installed, respectively.

These static eliminator 7 and charging device 6 are corona dischargers formed by charging wires 26 and 25'iz stretched inside the case, and as shown in FIG. 7, charging device 6 is connected to a DC high voltage power source. An AC high voltage power source is connected to the static eliminator 7. In FIG. 2, reference numeral 22 is a unit side plate, and 23 and 24 are bearings.

Now, turn on the power of the copying machine and press the START - TO button, and at the same time as the belt photoreceptor 13 starts running, or when the part of the belt photoreceptor that has started to be charged by the charger 14 reaches the driven roller 10. When a voltage of DC5KV or more is applied to the charge wire 25 of the charging device 6 at this time, an electric charge is applied to the surface of the polyester film on the back side of the belt photoreceptor 13, and when that part is transported to the exposure section, the aluminum An electrostatic attraction phenomenon occurs between the flat contact surface of the flat surface maintaining member 8 and the belt photosensitive weight 3.
follows the surface of the plane maintenance device and runs while maintaining a perfect plane. When the tip of the charging section passes the front end of the flatness maintaining device 8, a voltage of 5 KV or more AC is applied to the charge wire 26 of the static eliminator 7 to remove the electric charge on the surface of the polyester film of the belt photoreceptor 13. As a result, it is possible to avoid paper dust and the like from being attracted to the back surface of the belt photoreceptor 13 during normal running, and from increasing the load due to unnecessary adsorption force on the slack side of the belt and causing it to slip with the drive roller 9.

Note that the static eliminator 7 may be arranged downstream of the drive roller 9. By doing so, it is also electrostatically attracted onto the drive roller 9, thereby preventing slippage and increasing the drive transmission force.

The shape of the flat part of the flat surface maintaining member 8 may be such that the entire surface is in contact with the belt photoreceptor 13VC, but in this embodiment, taking into consideration the sliding friction load, the shape of the flat part of the flat part of the flat surface maintaining member 8 may be changed to an appropriate shape as shown in FIGS. 4 and 5. There is a ``slip'' in the.

Now, as shown in Figure 6, the final copy of continuous copying (
or when copying only one sheet) When the image forming point reaches the final image forming position P, the charging device 6 is turned off, and the belt photoreceptor 1 is turned off.
Stop applying the charge to the back side of belt photoreceptor 1.
3, only the static eliminator 7 is operated to eliminate static electricity. When the copy is ejected to a paper ejection tray outside the machine and the point where the charging device is turned off reaches the static eliminator 7, the belt photoreceptor 13 stops running. Through this process, the entire circumference of the belt photoreceptor 13 is completely neutralized.

As a result, the belt photoreceptor 13 can be safely attached and detached. If you stop the belt photoreceptor, release the tension, and attach/detach the belt photoreceptor without performing the static electricity removal work, the belt photoreceptor itself may peel off between the driving roller, driven roller, and belt photoreceptor. Since electric charges are accumulated on the back surface of the belt photoreceptor due to charging or frictional charging at the sliding part, a discharge occurs between the operator's hand and the belt photoreceptor, and the worker feels an electric shock.

FIGS. 8 to 11 are diagrams showing other embodiments of the present invention, and correspond to FIGS. 4 to 7 of the above embodiment, respectively.

In this embodiment, a DC high-voltage power source and an AC high-voltage power source can be connected to the corona discharger 6 on the rear side of the flatness maintaining member 8 with respect to the traveling direction of the belt photoreceptor, by switching between the DC high-voltage power source and the AC high-voltage power source as shown in FIG. When a DC voltage is applied, it functions as a charging device, and when an AC voltage is applied, it functions as a static eliminating device. Therefore, the static eliminator 7 is not provided on the front side of the flat surface maintaining member 8. The rest of the configuration is the same as the previous embodiment.

In the apparatus of this embodiment, as shown in FIG.
Switch to voltage higher than KV. That is, the role of the static eliminator is changed from that of the static charger until now. Therefore, after that, the surface of the polyvarnish 7/lz film on the back side is neutralized by the belt photoreceptor 13ij and the corona discharger 6vc.
The belt stops running after the entire circumference of the belt photoreceptor is neutralized. As a result, the belt photoreceptor can be attached and detached safely as in the previous embodiment.

However, in the case of this embodiment, the static electricity is not removed from the film surface on the back side of the belt photoreceptor until the final copy, so the adsorption force becomes unduly large on the slack side of the belt, that is, in this example, around the developing section. It is necessary to appropriately adjust the amount of charge to prevent slipping with the drive roller.

In the embodiments described above, an example was explained in which the plane maintaining device according to the present invention was provided in an exposure section where the image forming point moves on one plane. It can also be used in areas that require flatness, such as the part facing the charging charger Z41C equipped with a plurality of charge wires 2 and the part facing the developing device I5 equipped with a plurality of developing rollers in the example shown in Fig. 2. be. Is there much suction force on the loose side, that is, in the vicinity of the developing section I5 in the apparatus shown in Fig. 2? If it increases, it may cause slippage with the drive roller as described above, so care must be taken.

Effects As described above, according to the present invention, the belt can be moved in areas where it is necessary to run the belt-shaped photoreceptor while maintaining a completely flat surface, such as in an exposure area where an image forming area moves on one plane. It is possible to improve the flatness of the photoreceptor, prevent vibration of the belt, and prevent electric shock when the belt photoreceptor is attached or detached.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an exposure optical system in which an image forming point moves on one plane, FIG. 2 is a cross-sectional view showing the overall configuration of a copying apparatus according to an embodiment of the present invention, and FIG. 3 is a belt exposure system of the same. 4 is a perspective view showing the vicinity of the horizontal maintaining member of the embodiment, FIG. 5 is a sectional view of the same part, FIG. 6 is a sectional view illustrating its function, and FIG. 7 1 is a circuit diagram showing the connection of a power source to a charger and a static eliminator in this embodiment. FIGS. 8 to 11 are drawings corresponding to FIGS. 4 to 7 in the aforementioned embodiment of another embodiment of the present invention. 6... Charging device (also serves as a static eliminator in the second embodiment) 7... Static eliminator 8... Flatness maintaining member 9... Drive rollers 10, 11, 12... Driven roller I3 ...Belt photoreceptor l31L...Dielectric film 13b...
Metal conductive material layer 13c...organic photoconductive layer FIG. 2, FIG. 3! '5'i Figure 4 pr, 5 j-1 Figure 6 Figure 8 Figure 9

Claims (5)

[Claims] (1) A flexible endless belt photoconductor, which is made of a dielectric film laminated with a conductive material layer and an organic photoconductive layer, is passed through the belt under tension by a plurality of rollers. A flatness maintaining member made of an electrically conductive material and having a flat surface that comes into contact with the back surface of the belt photoreceptor is provided in a portion where flatness is required. An electrostatic copying apparatus comprising: a charging device for a dielectric film; and a static eliminator for removing charges charged by the charging device. (2) The electrostatic copying apparatus according to claim 1, wherein the static eliminator is disposed downstream of the flatness maintaining member. (3) According to claim 2, the charging device is controlled to be released at the same time as the process step on the flatness maintaining member is completed in the final round of continuous copying of multiple sheets. The electrostatographic apparatus described. (4) The electrostatic copying apparatus according to claim 1, wherein the charging device is also used as the static eliminating device by switching its power source from a DC high voltage power source to an AC high voltage power source. (5) The charging and neutralizing device is controlled so that it functions as a charging device until the process step on the flatness maintaining member is completed during the final copy of continuous copying, and is switched to the static eliminating device at the same time as the process step is completed. An electrostatic copying apparatus according to claim 4, characterized in that the electrostatic copying apparatus is configured as follows.