JPH05346740A - Image forming device - Google Patents

Abstract

PURPOSE:To make the device small in size and low in cost by eliminating a mechanism for recovering residual toner on a photosensitive body. CONSTITUTION:This device is provided with the photosensitive body 3, an electrifying brush 1 by which electrifies the surface of the body 3, a belt 12 being an intermediate transfer medium which runs in contact with the photosensitive body 3, a heater 10 which instantaneously heats and presses the belt 12, and a pressure roller 15. In the device, a toner image on the photosensitive drum 3 is transferred once on the belt 12, a printing medium is run at almost the same speed as the belt 12, and transfer and fixing are simultaneously executed. A cleaning member 20a for removing residual toner on the belt 12 is disposed on the belt 12 in the position further downstream than the heater 10 and the pressure roller 15. At the time of starting printing, prescribed potential is applied to the photosensitive body 3 and the belt 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a facsimile and a copying machine which uses an electrophotographic process.

[0002]

2. Description of the Related Art A conventional image forming apparatus will be described with reference to the drawings.

FIG. 5 is a vertical cross-sectional view of a structural example of an image forming apparatus using a conventional electrophotographic process. In FIG. 5, in the conventional image forming apparatus, the toner on the photoconductor 101 is transferred to the recording medium 111 by the transfer charger 109 by the corotron method. Generally, the efficiency with which the toner on the photoconductor 101 is transferred to the recording medium 111 (hereinafter referred to as transfer efficiency) is approximately 80 to 90%.
There was always about 0.3 to 0.1 mg / cm ² of toner remaining on No. 01. The resistance of the recording medium 111 is
Since the type of the recording medium 111 and the environment such as temperature and humidity greatly vary, the transfer efficiency may be lower than the above value and the amount of residual toner may be higher than the above value in some cases. If the toner remains on the photoconductor 101, it adversely affects the charging, exposure, and development processes in the next process, and thus is removed by the box-shaped cleaner 107. Then, after the toner image on the photoconductor 101 is transferred onto the recording medium 111, it is thermally fixed by a heat rotor 112 using a halogen lamp as a heat source.

Immediately after the start of printing, the following three types of stains were generated.

(1) When the apparatus is stopped, the trace of the toner on the portion where the photoconductor 101 and the toner carrier 105 are in contact with each other,
Immediately after the start of printing, the toner adheres to the photoconductor 101 (hereinafter referred to as a development nip mark).

(2) The poorly charged toner on the toner carrier 105 adheres to the photoconductor 101 immediately after the start of printing (hereinafter referred to as initial fog).

(3) Toner carrier 105 immediately after the start of printing
The toner on the toner carrier 105 adheres to the photoconductor 101 when the developing bias applied to (1) rises (hereinafter, referred to as dirt when the developing bias rises). Such a stain at the start of printing is a box-shaped cleaner 107.
Had been removed.

[0008]

In the conventional image forming apparatus, as described above, the residual toner is always present on the photoconductor after the transfer, and for example, in order to collect the residual toner for printing several thousands of sheets, However, a box-shaped cleaner with a large capacity was required, which led to an increase in the size of the device.

Further, since the toner flows on the toner on the photosensitive member in the lateral direction in the lateral direction and the transfer is performed before the fixing is performed, the traveling distance of the recording medium becomes long and the traveling route of the traveling medium is complicated. And the size of the device was increased. Furthermore, the transfer by the corotron method is several kv on the wire.
Since the corona discharge is applied by applying the voltage, there is a pollution of the atmosphere due to the generation of ozone, and a filter and a fan for removing the pollution are required. In addition, in the heat fixing method using a heat rotor using a halogen lamp, it takes several tens of seconds until the temperature at which the toner can be fixed is reached, and it is impossible to use it immediately after turning on the power of the apparatus.

The present invention solves the above problems, and particularly provides a system for removing the developing nip trace at the start of printing.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to an electrostatic latent image carrier, charging means for charging the surface of the latent electrostatic image carrier, an intermediate transfer medium which runs on the electrostatic latent image carrier, Equipped with a heating / pressing mechanism that instantaneously heats and presses the intermediate transfer medium,
In an image forming apparatus that transfers the toner image on the electrostatic latent image carrier to the intermediate transfer medium once, and causes the print medium to run at substantially the same speed as the intermediate transfer medium for the entire period to perform transfer and fixing at the same time, It has a cleaning member arranged downstream of the heating / pressing mechanism on the intermediate transfer medium for the entire period.

Further, the cleaning member is
It may be mounted on a pressing mechanism, and further, the cleaning member may be excluded, and the brush-like, sheet-like, or sheet-like structure may be provided downstream of the intermediate transfer medium of the electrostatic latent image carrier and upstream of the charging unit. It may have any one of the felt-like members.

At the start of printing, a voltage having a polarity different from that of the toner may be applied to the base material of the electrostatic latent image carrier, and the intermediate transfer medium may be connected to GND. The base material of the image carrier may be connected to GND and a voltage having the same polarity as the toner may be applied to the intermediate transfer medium. Further, a voltage having the same polarity as that of the toner may be applied to the base material of the electrostatic latent image carrier, and the intermediate transfer medium may be electrically floated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of the present invention. 2A and 2B are schematic diagrams showing the first and second embodiments of the present invention, and FIGS. 3A and 3B show the third and third embodiments of the present invention. It is a schematic diagram which shows a 4th Example. 4 (a) to 4 (d) are views for explaining changes in voltage between the base material and the belt in the first to fourth embodiments of the present invention.

The case of the reversal development method using a toner having a negative polarity will be described below.

In the first embodiment of the present invention, a non-voltage is applied to the charging brush 1 made of fibers such as acrylic and rayon,
One example of an electrostatic latent image carrier is an OPC (Organic Photocon
The photoconductor 3 such as a ductor) is uniformly negatively charged, and the photoconductor 3
The initial potential is applied to the surface of. A laser not shown,
Exposure 2 of image data is performed from a light source such as an LED or a liquid crystal to form an electrostatic line image. The toner 7 is guided from the stirring member 8 to the supply roller 5 made of a conductive or insulating sponge, aluminum, or the like, and the silicone rubber, urethane rubber,
The toner is guided to the toner carrier 4 made of a flexible material such as nitrile butylene rubber, natural rubber, or a member obtained by surface-treating a sponge.

The toner 7 guided to the toner carrier 4 is regulated by a regulating blade 6 made of a spring member made of metal such as stainless steel, phosphor bronze, nickel silver, etc. to form a uniform thin layer. The toner 7 is negatively charged by friction. A negative voltage is applied to the toner carrier 4, and the charged thin layer toner 7 on the toner carrier 4 is electrostatically charged on the photoconductor 3 when facing the photoconductor 3. The image is attached to the latent image and developed.

The photosensitive member 3 is composed of a conductive base material 3a such as aluminum and a photosensitive photosensitive layer 3b. A voltage having the same polarity as the toner charging polarity is applied to the base material 3a. ing. Further, the surface of the belt 12 on the side of the photoconductor 3 has an electric property, and is grounded to GND by a grounding member 19. The grounding member 19 is a conductive brush-like member made of fibers such as acrylic and rayon, and the transfer roller 11 has flexibility and presses the photoconductor 3 with the belt 12 interposed therebetween. ing. The transfer roller 11 is electrically driven,
It may have any one of insulating properties, and the shape is not limited to the cylindrical shape, and may have any shape as long as it is a member that presses the photoconductor 3. Then, according to the sequence shown in FIG. 4A, when the developed toner 7 on the photoconductor 3 faces the belt 12, it is transferred to the belt by the electric field applied between the base material 3 a and the belt 12. .. The toner 7 transferred to the belt 12 is the drive roller 14
Is conveyed to a heater 10 capable of instantaneous heating, the toner 7 is melted by the heater 10 and is pressed by a pressure roller 15, so that transfer and fixing are simultaneously performed on a recording medium 16 such as paper or an OHP sheet. ..

In FIG. 2A, immediately after the start of printing, the photosensitive member 3 and the toner carrying member 4 start rotating about 0.5.
When the photoconductor 3 and the toner carrier 4 having a width of mm to 1.5 mm are stationary, the toner 7 interposed therebetween, that is, the developing nip trace 21 is attached to the photoconductor 3. The development nip trace 21 on the photoconductor 3 is transferred to the belt 12 when facing the belt 12. On the belt 12, the heater 1
A simple cleaning member 20a made of felt or the like is attached at a position downstream of 0,
A simple cleaning member b made of felt or the like is attached on the pressure roller 15. And
The developing nip mark 21 on the belt 12 is formed by the cleaning member 2
0a and the cleaning member 20b. The developing nip mark 21 attached to the pressure roller 15 stains the back surface of the recording medium 16, so that the cleaning member 20b can be omitted depending on the degree of the stain.

In the second embodiment of the present invention, the method of developing the electrostatic latent image on the photoconductor 3 and transferring it to the belt 12 and then transferring and fixing it to the recording medium 16 is the same as the first embodiment. Is the same as. In FIG. 2B, in the sequence shown in FIG. 4B, only when the development nip trace 21 attached to the photoconductor 3 faces the belt 12 immediately after the start of printing, the toner 7 is reversely attached to the base material 3 a. When a polarity voltage (a positive voltage in the case of the reversal development method using the negative polarity toner of the embodiment of the present invention) is applied,
The development nip trace 21 on the photoconductor 3 is not transferred to the belt 12. The toner leveling member 22, which is located downstream of the belt 12 on the photoconductor 3, flattens or removes the current nip trace 21 on the photoconductor 3. The toner leveling member 22 includes, for example, a brush-shaped inner member, a sheet member, a felt member, and the like. It has been confirmed by experiments that if the development nip trace 21 is leveled to about 0.1 mg / cm ² or less, it does not affect the next process.

In the third embodiment of the present invention, the electrostatic latent image on the photoconductor 3 is developed, transferred to the belt 12, and then transferred and fixed on the recording medium 16. Is the same as. In FIG. 3A, in the sequence shown in FIG. 4C, the base material 3a is connected to the GND only when the developing nip trace 21 attached to the photoconductor 3 faces the belt 12 immediately after the start of printing. When a voltage having the same polarity as that of the toner 7 (a negative voltage in the case of the reversal development method using the negative polarity toner of the embodiment of the present invention) is applied to the belt 12, the development nip mark 21 on the photoconductor 3 is left on the belt 12. Not transferred to. Then, the toner leveling member 11 located downstream of the belt 12 on the photoconductor 3 flattens or removes the development nip trace 21 on the photoconductor 3.

In the fourth embodiment of the present invention, the method of developing the electrostatic latent image on the photosensitive member 3, transferring it to the belt 12, and transferring and fixing it to the recording medium 16 is the above-mentioned first embodiment. Is the same as. In FIG. 3B, in the sequence shown in FIG. 4D, only when the developing nip mark 21 attached to the photoconductor 3 faces the belt 12 immediately after the start of printing, the belt 12
Is electrically floated from the GND connection state. The development nip trace 21 remains attached to the photoconductor 3 due to the Van der Waals force and the image force, and the development nip trace 21 on the photoconductor 3 is not transferred to the belt 12. Then, at a position downstream of the belt 12 on the photoconductor 3,
The toner leveling member 22 levels out or removes the development nip trace 21 on the photoconductor 3.

[0024]

EFFECT OF THE INVENTION Since the toner on the photoconductor is limited to the intermediate transfer medium and transferred once, the transfer efficiency does not change even if the type of the recording medium changes, and a stable high transfer efficiency can be obtained. .. Further, the intermediate transfer medium is more stable and does not change in electric resistance and the like than the recording medium due to changes in environment such as temperature and humidity. Therefore, almost no toner remains on the photoconductor,
A box-shaped cleaner with a large capacity for collecting residual toner is not required, and only a small cleaning member that removes only the development nip trace at the start of printing can be covered.
The size of the device can be reduced.

Further, since the toner image is transferred and fixed on the recording medium at the same time, the lateral width of the apparatus can be shortened. Therefore, the distance that the recording medium travels is short,
Moreover, the path along which the recording medium travels is simplified, and the size and cost of the device can be reduced.

Further, as the transfer method, not the corotron method, but the bias transfer and the transfer by pressure and heat are adopted, so that ozone is hardly generated, and a filter or a fan for removing ozone is not required. Also, as a fixing system, a heating mechanism that can instantly heat is adopted,
It is possible to turn on the device and use it immediately.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

2A and 2B are schematic diagrams showing first and second embodiments of the present invention.

FIGS. 3A and 3B are schematic views showing third and fourth embodiments of the present invention.

4A to 4D are diagrams for explaining voltage changes between a base material and a belt according to first to fourth examples of the present invention.

FIG. 5 is a schematic view showing an example of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charging brush 2,10 Exposure 3,101 Photoconductor 3a Base material 3b Photosensitive layer 4,105 Toner carrier 5 Supply roller 6 Regulation blade 7,106 Toner 8 Stirring member 9,108 Static elimination light 10 Heater 11 Transfer roller 12 Belt 13 Tension roller 14 Drive roller 16,111 Recording medium 19 Grounding member 20a, 20b Cleaning member 21 Development nip mark 22 Toner leveling member 102 Charger charger 104 Toner hopper 107 Cleaner 109 Transfer charger 110 Separation charger 112 Heat roller

Claims (6)

[Claims] 1. An electrostatic latent image carrier, a charging means for charging the surface of the electrostatic latent image carrier, an intermediate transfer medium which runs while traveling on the electrostatic latent image carrier, and instantaneous heating and pressing of the intermediate transfer medium. The toner image on the electrostatic latent image carrier is once transferred to the intermediate transfer medium, and the print medium is run at substantially the same speed as the intermediate transfer medium to perform transfer and fixing. In the image forming apparatus which is performed at the same time, the image forming apparatus further comprises a cleaning member arranged downstream of the heating / pressing mechanism on the intermediate transfer medium. 2. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the cleaning member is mounted on the heating / pressing mechanism. 3. The image forming apparatus according to claim 1,
The cleaning member is excluded, and any one of a brush-shaped, sheet-shaped, or felt-shaped member is provided downstream of the intermediate transfer medium of the electrostatic latent image carrier and upstream of the charging unit. An image forming apparatus characterized by. 4. The method according to claim 3, wherein a voltage having a polarity different from that of the toner is applied to the base material of the electrostatic latent image carrier at the start of printing, and the intermediate transfer medium is connected to GND. Image forming apparatus. 5. The method according to claim 3, wherein the base material of the electrostatic latent image carrier is connected to GND and a voltage having the same polarity as the toner is applied to the intermediate transfer medium at the start of printing. Image forming apparatus. 6. The method of applying a voltage having the same polarity as that of toner to the base material of the electrostatic latent image carrier at the start of printing, and electrically floating the intermediate transfer medium. 3. The image forming apparatus according to item 3.