JP2002229285A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that a jamming is easily caused and the jamming processing is complicated and difficult since the space inside an image forming device is narrow, in a recent copying machine, etc., aiming space saving. SOLUTION: In the device, a large capacity paper loading means of high reliability is utilized for paper with high frequency of use and other paper feeding is carried out by a simple paper feeding tray with multiple trays. Furthermore, the image forming device with few cases of jamming is obtained by carrying out vertical installment of an intermediate transfer belt, vertical installment of a developing device, adopting vertically long ones, and making a carrying path as short and straight as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
The present invention relates to a facsimile, a printer, and a multifunction peripheral having these functions.

[0002]

2. Description of the Related Art <Conventional example 1> An old analog type copying machine has a document reading unit on the upper surface of an image forming apparatus main body, a paper feed cassette is laid out on one side, and paper is discharged on the opposite side. Most of it was very disturbing where the horizontal size was large and there was not much office space. FIG. 4 shows a typical example. In Conventional Example 1, a paper feed unit 51, a conveyance path 52, a registration roller pair 53, an image forming unit 54, a fixing unit 55, a discharge roller pair 56, a paper discharge tray 57, an automatic document feeder 58, an optical unit 59, etc. Consists of The paper fed from any of the paper feed cassettes (511 to 513) passes through the transport path 52, and is temporarily stopped by the registration roller pair 53 for synchronization with the timing of reading the original and alignment of the leading edge of the paper. At an appropriate timing, the toner image is transferred by the image forming unit 54, and subsequently, the toner image is fixed by being nipped and heated by the heat roller and the pressure roller at the fixing unit 55, and thereafter discharged to the paper discharge tray 57. In such a configuration, a plurality of paper feed cassettes (511 to 513) are set from the right side in the figure, and a considerable distance to the left end of the paper discharge tray 57 is required. Further, the sheet cassettes (511 to 511)
Since 513) is inserted / removed from the right direction, the installation direction with a space is required in the direction where the cassette is substantially located. However, since the transport path 52 is substantially horizontal in a straight line from the paper supply to the discharge, the occurrence of paper jams is small,
It can also be said that the processing was easy. Since the lower part in the figure is not particularly used, it is often placed on a large desk or on a dedicated desk 60 with casters.

<Conventional Example 2> Accordingly, a front loading system in which a drawer cassette capable of replenishing sheets from the front is laid out under the image forming apparatus main body has appeared, and sheets are transferred from a sheet feeding cassette below an image forming unit. Paper feed, vertical conveyance, conveyance in the horizontal direction, transfer of a toner image, fixing, and then discharge have become mainstream. As a result, since the cassette does not protrude in the lateral direction, considerable space saving can be realized. FIG. 5 is an example. The second conventional example includes a sheet feeding unit 61, a conveying path 62, a pair of registration rollers 63, an image forming unit 64, a fixing unit 65, a both-side branching unit 66, a pair of discharge rollers 67, a discharge tray 68, an automatic document feeder 69, Digital optical unit 70, switchback unit 71, double-sided conveyance path 72
In the case of one-eye printing, the paper fed from either the paper feed cassettes (611 to 613) or the paper feed tray 614 passes through the transport path 62 and the latent image from the LSU to the photosensitive drum. Synchronization with the write timing of the
And temporarily stops at the registration roller pair 63 to align the leading edge of the sheet.
The toner image is transferred onto the surface, and then the toner image is fixed by being nipped and heated by the fixing roller 65 and the heat roller and the pressure roller. For both sides,
The paper printed on the first surface is sent to the switchback unit 71 by the double-sided branching unit 66 to switch back the transport direction, joins the transport path 62 again, is printed on the second surface of the paper, and is discharged. However, in such a configuration, there is a problem that the transport distance from paper feeding to paper discharging is long even in one-sided printing. Immediately after the sheet is fed, the sheet is conveyed vertically upward against the gravity and turned 90 °. For this reason, the paper cassette (611-613)
, The lower the paper feed cassette 613, the higher the jam occurrence rate.

<Conventional example 3> In recent years, since the space to be discharged is also obstructive, the discharge of the paper is performed on the upper surface of the image forming apparatus, and the copying machine has been digitized. The optical path for exposing to the photoconductor drum is eliminated, and the photoconductor drum can be exposed by laser or LED, so there is no restriction on the layout, and copiers and printers that discharge inside the cylinder have appeared, enabling further space saving. Was. FIG. 6 shows an example. In the third conventional example, a paper feed unit 68, a conveyance path 82, a pair of registration rollers 83, an image forming unit 84, a fixing unit 85, a discharge port 86, an in-body discharge tray 87, an automatic document feeder 88, a digital optical unit 89 The paper fed from either the paper feed cassettes (811 to 813) or the paper feed tray 814 passes through the transport path 82, and the timing of writing the latent image from the LSU to the photosensitive drum is determined. Sync,
The toner image is temporarily stopped by the pair of registration rollers 83 to align the leading edge of the sheet, the toner image is transferred to the sheet by the image forming unit 84 at a certain timing, and then the fixing unit 85 is nipped and heated by the heat roller and the pressure roller. After the toner image is fixed, the toner image is discharged to the internal discharge tray 68. However, in such a configuration, more space can be saved, but the paper conveyance repeats a sharp curve, so that the occurrence rate of the jam increases.
Jam processing is also becoming difficult due to the more complicated transport path.

[0005]

As described above, as the conventional front-loading method and the method of discharging the image onto the upper surface of the image forming unit or the inside of the drum become longer, the distance for transporting the paper becomes longer and the steepness is increased. Inversions on curves have come to be forced. For this reason, paper handling technology becomes complicated, and the occurrence of jam tends to increase. Further, since the paper transport path is complicated, the jam processing is also difficult, and it is necessary to provide an opening and closing mechanism everywhere, so that the entire image forming apparatus becomes complicated. In fact, when looking at a place where a jam has occurred in a copying machine or the like in recent years, it frequently occurs in a curved portion where the above-mentioned conveyance is impossible, a confluence of sheets, or the like.

On the other hand, in recent years, from the viewpoint of resource saving, recycled paper, recycled paper, reuse of paper printed on only one side, and poor quality paper such as rough paper have been used. It can be said that this tendency further increases the incidence of jams.

When looking at the usage of a copying machine in a general office, most use A4 plain paper. At present, other A3 paper and B-size paper are hardly used. Envelopes and postcards are often not copied at all. However, even if the size of the paper sheet is rarely used, the cassette occupies one stage. For this reason, the place of frequently used paper is cut off, and the paper is frequently set.

As described above, the concept of the present invention is to make the frequently used paper as straight and short as possible. Except for cassettes that store frequently used sheets, paper is basically fed from the bypass. By performing the conveyance from the paper supply to the discharge in the horizontal direction or from the top to the bottom, the jam due to the slip is reduced. For a paper supply unit that is frequently used, a paper supply technology with high reliability is used.

[0009]

According to a first aspect of the present invention, there is provided a paper cassette capable of stacking a plurality of paper sheets, and a paper cassette for feeding paper sheets one by one to a transport path. Paper means, a pair of registration rollers for adjusting the timing of adjusting the timing of the leading edge of the conveyed paper,
An electrophotographic image forming unit having a developing device provided with a developing roller for forming a toner image on a photosensitive drum; and a toner image formed by the image forming unit is transferred at a primary transfer position, and is transferred to a secondary transfer position. In an image forming apparatus having an intermediate transfer belt for transferring the toner image to a sheet, fixing means for fixing the sheet on which the toner image has been transferred, and discharge means for discharging the sheet, the intermediate transfer belt is substantially The first transfer is performed on the surface of the intermediate transfer belt that is positioned substantially perpendicularly to a horizontal transport path, and the second transfer is performed at a lowermost position of the intermediate transfer belt. The image forming apparatus is characterized in that the position of the sheet feeding unit, the position of the resist, the position of the secondary transfer, the position of the fixing unit, and the position of the discharging unit are substantially linear.

According to a second aspect of the present invention, the image forming means uses a vertical developing device in which a developing roller faces substantially upward of a photosensitive drum and a stirring means is arranged in a substantially vertical direction. The image forming apparatus according to the first aspect of the invention.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner container is laid out on the developing device and the upper portion of the intermediate transfer belt. The image forming apparatus according to the first or second invention is used.

According to a fourth aspect of the present invention, a plurality of simplified paper feed trays and one common bypass conveyance path are provided above the paper cassette, and a plurality of simplified paper feed trays are selectively provided. Paper is possible and this bypass transport is
The image forming apparatus according to any one of the first to third inventions, wherein the image forming apparatus merges in a conveying direction from a diagonally upward direction to a position downstream of a sheet feeding unit of the large capacity paper cassette and upstream of a registration roller pair. Used.

According to a fifth aspect of the present invention, there is provided a method for lifting a sheet from a first discharge position for discharging the discharge tray to a second discharge position where the user can easily take out the discharged sheets. A first sheet discharging tray lifting means;
The image forming apparatus according to any one of the first to fourth aspects of the present invention is used.

According to a sixth aspect of the present invention, the paper cassette is capable of storing a large amount of paper, is built in the main body of the image forming apparatus, and can be pulled out to the front.
The image forming apparatus according to any one of the first to fifth aspects of the present invention is used.

[0015]

According to the first aspect of the present invention, the intermediate transfer belt is vertically disposed, and the primary transfer is performed on the surface of the intermediate transfer belt which is positioned substantially vertically on the horizontal conveyance path, and the secondary transfer is performed on the intermediate transfer belt. By performing the transfer at the lowermost position of the transfer belt, the space for transferring the toner image to the sheet is shortened, the distance between the registration roller and the fixing unit can be reduced, and the sheet conveyance distance is shortened. In addition, the number of paper cassettes that are frequently used is reduced to one, and the distance from the paper feeding position to the discharge is made substantially straight, so that the paper transport distance can be further reduced.

In the second aspect of the present invention, the space can be further reduced by using a vertical stirring means for the developing device.

In the third aspect of the present invention, since the toner storage container is laid out above the intermediate transfer belt and the developing device, the space formed by the toner storage container, the intermediate transfer belt and the developing device becomes vertically long, and the toner on the paper is formed. The image transfer space is shortened.

In the fourth aspect of the present invention, a plurality of simplified paper feed trays are used for feeding paper other than the main size paper cassette, so that paper that is rarely used can be fed from here. Since a plurality of the simplified paper feed trays are prepared, it is possible to set a plurality of types other than the main paper. Since the usage rate of the sheets other than the main sheet is less than a few percent of the whole, it is sufficient to feed the other sheets from the bypass at any time. Further, although the usage rate of the papers other than the main paper is low, since there are many types of each type (a small number of types), a plurality of simplified trays are provided. By providing a plurality of cassettes, more types of paper can be set in a smaller space. In addition, since these simplified paper feed trays are located above the main paper feed cassette, the paper is conveyed from above to below, and the slip of the conveyance rollers can be reduced.

In the fifth aspect of the present invention, since the sheet is conveyed from the top to the bottom, the sheet is discharged downward. Therefore, this is compensated for by lifting the discharge tray. This is because, if a paper path is provided and the paper is discharged upward, paper that may curl after fixing is conveyed from the bottom to the top. Discharged paper does not jam.

In the sixth aspect of the present invention, by using a large-capacity paper cassette as the paper cassette and incorporating the paper cassette in the main body of the image forming apparatus, the distance from paper feeding to paper discharging can be further reduced. Furthermore, by using a drawer that can be pulled out to the front, a space in the left-right direction is not taken up much. This is because the front loading system includes a special cassette, but the size is considerably large.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment employing the present invention will be described with reference to FIG. In the figure, the image forming apparatus includes a large capacity cassette 01, a sheet feeding unit 02, a registration roller pair 03,
, Conveying path 04, image forming means 05, intermediate transfer belt unit 06, secondary transfer roller 07, fixing means 0
8, a discharge means 09, a discharge tray 10, a simplified paper feed tray 11, a scanner 21, an automatic document feeder 22
It is composed of

The large capacity cassette 01 and sheet feeding means will be described with reference to FIG. In this figure, the large-capacity cassette 01 includes a cassette frame 011 and a sheet stacking plate 01.
2. Sheet sensor 0121, sheet loading plate elevating means 013
Etc., and only the main paper is loaded. In general offices, the paper size that is often used is A4, and digital copiers are mainly used in recent years. Further, from the viewpoint of increasing the number of printed sheets per time, the transport direction is preferably the horizontal direction. Since only one sheet cassette is provided, the space for other sheet cassettes is not secured, and the vertical conveyance path as described in the related arts 2 and 3 is not provided, so that a large capacity can be realized. Further, even if a large-capacity cassette having a large number of parts is used, the cost is not significantly increased because only one cassette itself is used. The paper sensor 012
Reference numeral 1 uses a photo sensor or the like to detect the presence / absence of paper loaded on the paper loading plate 012.

The sheet loading plate lifting / lowering means 013 includes a motor (01321, 0131b) and a driving pulley (0132).
a, 0132b), wires (0133a, 0133)
b) and idle pulleys (0134a, 0134b). When feeding paper, the upper surface of the uppermost sheet loaded on the sheet loading means 01 and the sheet feeding means 02
Is controlled so that the distance of the portion for sucking the sheet is maintained at a predetermined distance. The predetermined distance is determined by various related parameters such as the air volume of the sheet blowing unit 023, the suction force of the sheet suction unit 022, the weight of the sheet per sheet, the sheet size, and the coefficient of friction between sheets. When the sheet is being conveyed, the distance between the sheet and the sheet to be fed next is such that the sheet to be fed next does not start moving due to the frictional force between the sheet and the sheet to be fed next. The distance is such that one sheet of paper can be attracted to the lower surface side of the paper feeding belt 021 by the air flow amount and the suction force of the paper suction means 022. Alternatively, the predetermined distance may be set in advance, and the other related parameters may be determined. Further, the sheet stacking plate elevating means 013 is used for replenishing sheets and performing sheet jam processing.
It also plays a role such as lowering to a predetermined position.

The paper feeding means 02 includes a paper feeding belt unit 21, a paper suction means 022, and a paper blowing means 02.
The sheet blowing means 022 is configured to blow air from the downstream side in the sheet transport direction from the downstream side in the sheet conveyance direction through the air blowing port 0232 from the blowing fan 0231 to the upper part of the plurality of sheets stacked on the sheet stacking plate 012. The paper is blown by spraying. The paper feeding belt unit 021 has at least two rollers (0212, 021
3) and a plurality of belts (021) which are wound around the at least two rollers at substantially equal intervals and face the upper surface of the paper stacked on the paper stacking plate 012 on the downstream side in the paper transport direction.
1) and a part 0214 of a suction duct, and the paper suction means 022 is provided with a suction fan 022.
1 and a suction duct 0222. A plurality of paper suction holes (not shown) of the paper suction means 022 are provided, and when feeding paper from each of a plurality of holes of the belt, the paper stacking plate is provided. The uppermost one of the plurality of sheets stacked on the sheet No. 012 sucks the sheet to the lower surface of the plurality of belts 021, and further, when the belt is rotated to convey the sheet, the sheet is attracted to the lower surface. While being conveyed to the subsequent conveyance path 121.

Next, the basic operation of an image forming apparatus employing the above-described air suction type sheet feeding and conveying device will be described. First, it is determined whether or not there is a sheet on the sheet stacking plate 012. If there is no sheet, a paper empty is displayed and a replenishment of the sheet is requested. If there is a sheet, the distance between the lower surface of the sheet feeding belt and the upper surface of the uppermost sheet of the sheets stacked on the sheet stacking plate 011 is set to a predetermined distance, and the suction fan and the blowing fan 31 Check if it is working. Next, the paper is sucked by the lower surface of the paper feed belt 021. Subsequently, the paper feed belt 21 is rotated to transfer the paper to the paper feed path, and the paper feed belt is stopped. As described above, in the present invention, it is preferable to use a sheet capable of accurately feeding one sheet at a time.

The simplified paper feed tray 11 is provided with a plurality of paper feed trays similar to conventional bypass paper feeds. Here, the large-sized simplified paper feed tray 111, the medium-sized simplified paper feed tray 112, and the small-sized simplified paper feed tray 113
No matter when paper is fed from any of these, the paper feeding tray is inclined obliquely downstream of the paper feeding means 02 and upstream of the registration roller pair 03 via the bypass conveyance path 12 regardless of the paper feeding tray. Merges gently in the transport direction from above. For this reason, the fed paper does not go against gravity and the conveyance path does not have a particularly sharp curve, so that the occurrence of jams is extremely reduced. Each paper feed roller is made of ordinary urethane rubber, EPDM, or the like, and may be a simple roller having a flat knurl around the periphery to prevent slippage, or a complicated roller such as a gate system. This simplified paper feed tray is assumed to be used infrequently, so even if a simple paper feed roller is used, there is little wear and it is easy to replace, so it is enough to use a simple paper tray Play a role. Usually, such a schematic paper feed tray is openable and closable, and when it is not used, it often closes with the cover of the image forming apparatus, but in this embodiment, there are a plurality of schematic paper feed trays. Therefore, the sheet feeding position is provided inside the image forming apparatus main body, and a commonly used expanding and contracting tray is easily adapted.

The pair of registration rollers 03 is formed by appropriately pressing a rubber roller and a roller made of a resin such as polyacetal with good slipperiness, firstly sliding the conveyed paper tip against a resin roller, and sliding the paper by a nip. By stopping the tip, the tip is arranged parallel to the transport direction. The registration roller pair 03 rotates in synchronization with the image forming timing. Although the drawing is performed for a sheet fed from the large-capacity cassette 01, the air tray is used for the sheet feeding and the distance from the sheet feeding to the transfer position is very short. , And the double-side refeeding only, the distance from sheet feeding to discharge can be further reduced.

The image forming means 05 will be described with reference to FIG. In this figure, the image forming means 05 includes a photosensitive drum 051, a main charging device 052, an exposing device 053, a developing device 054, a drum cleaner 056, a toner container 057, and the like. Especially developing device 054
Uses a developing device having a vertical stirring means as in the second invention. The positional relationship between the transport path 04 and the developing device 054 is on the upper side so as not to interfere with the registration roller pair 03.

The photosensitive drum 051 has undergone a charging and exposing process before the development process. The main charging device 052 charges the surface of the photosensitive drum 051 to a predetermined surface potential. The one on which the information is exposed and an electrostatic latent image is formed on the peripheral surface is rotating.
The main charging device 052 uses a corotron system, a scorotron system, a charging roller, or the like, and generates a corona discharge by applying a high voltage or charges the surface of the photosensitive drum 051 to a predetermined surface potential by injecting charges. Let me. Here, the exposure means 053 uses LPH (LED PRINT HEAD) to save space, but LSU or the like may be used if space permits.

The developing device 054 includes a developing housing 054.
1, a developing roller 0542, a supplementary cutting plate 0543, a first stirring means 0544, a second stirring means 0545, a pumping roller 0546, and the like. The developing housing 0541 is a housing of the developing device main body, maintains components of the developing device in a predetermined positional relationship, and is a tank for the developer. In general, the material is made of a resin containing glass fiber or the like to achieve dimensional accuracy. First stirring means 0544,
The second stirring unit 0545 uses a stirring paddle or a spiral to stir the developer including the carrier particles and the toner,
The toner is uniformly mixed by being conveyed, causing frictional charging to charge the toner.

The developing roller 0542 is disposed in the developing housing 0541 in parallel with the photosensitive drum 051, and has a sleeve member that rotates in a forward direction with respect to the rotational movement direction of the peripheral surface of the photosensitive drum 1. It is constituted by a magnet provided in the sleeve member. The sleeve member attracts and transports the developer to the peripheral surface, sends the developer to a developing area where a nip is formed with the photosensitive drum 051, and applies the developer to the electrostatic latent image on the peripheral surface of the photosensitive drum 051. Form a toner image. Here, an appropriate developing bias is applied to the first sleeve member, and an electrostatic latent image on the peripheral surface of the photosensitive drum 1 is formed by forming an electric field using the photosensitive drum 051 as a counter electrode. A toner image is formed. Generally, the material of the sleeve member is an aluminum alloy, and the peripheral surface thereof is subjected to knurling, sandblasting, and wire brushing in consideration of improvement in developer transport performance. The magnet has multiple magnetic poles in the radial direction, and is made of a ferrite-based permanent magnet (sintered or binder magnet).

The cutting board 0543 is provided with a developing roller 0542.
And has an end located at a predetermined gap, and has a role of regulating the layer thickness of the developer conveyed on the peripheral surface of the developing roller 0542. As the material, metals such as stainless steel, brass, and aluminum alloy are used in consideration of abrasion resistance and prevention of toner adhesion. Setting the layer thickness requires precision.

The pumping roller 0546 is located at a position deviated from the developing area of the developing roller in the longitudinal direction, and when transferring the developer from the first agitating means 0544 to the second agitating means 0545, it moves upward from the bottom. In this case, the developer from the first stirring means 0544 is magnetically attracted to the surface of the pumping roller 0546 and is peeled off to the second stirring means 0545 by a simple blade.

The toner concentration detecting means 0547 uses a magnetic permeability sensor, and may be installed at any location where the toner and the carrier particles are sufficiently stirred and the mixed developer flows.

Next, the flow of the developer will be described. First, the stirring of the developer is performed by circulating the first stirring means 0544 and the second stirring means 0545 via the pumping roller 0546. Further, the first stirring means 054
Reference numeral 4 agitates while circulating the developer to the developing roller 0542. The developing roller 0542 magnetically attracts and holds the developer on the peripheral surface by the magnetic poles of the magnets disposed inside the sleeve member, and the pumped developer is moved by the ear-cutting plate 0543 as the sleeve member rotates. The amount of the toner is regulated, and the toner is conveyed by the carrier magnetic pole and rises by the magnetic field generated by the main pole, and is sent to the developing area where the sleeve member and the photosensitive drum 051 are formed. After the development, the developer is continuously transferred to the first stirring means 0544 near the peeling magnetic pole of the same polarity adjacent to the internal magnet by the rotational movement of the sleeve member. This first stirring means 05
The developer having consumed the toner collected in 44 again becomes the first toner.
The toner is supplied and maintained at a predetermined density while circulating the stirring means 0544 and the second stirring means 0545 via the pumping roller 0546.

The toner container 057 includes a toner supply roller 0571, a toner feeding unit 0572, and the like.
By rotating the toner replenishing motor, the toner replenishing roller 0571 is rotated, and the second developer agitating / conveying means 05 of the developing housing 0541 is opened through the lower opening.
The toner is dropped on the upstream side of 45. This toner drop is performed by comparing the toner density of the developer measured by the toner density detecting means 0547 with the set toner density, and replenishing the toner when the measured toner density is lower than the set toner density. Then, the toner supply is stopped when the measured toner density becomes higher than the set toner density. The toner feeding unit 0572 rotates so as to move the toner toward the opening, and is driven by the same driving as the driving of the toner supply roller 0571.

In the first transfer section, the intermediate transfer belt 061
The toner image is transferred to the printer. The details here will be described below in the description of the intermediate transfer belt. Drum cleaner 056 is the first
The toner remaining at the transfer position is scraped off with a blade and collected.

Next, the intermediate transfer belt unit 06 and the second transfer roller 07 will be described with reference to FIG. The intermediate transfer belt unit 06 includes an intermediate transfer belt 061, a driving roller 062, and a first transfer roller 06.
3. Second transfer facing roller 064, tension roller 0
65, a belt cleaner 066 and the like. As can be seen from the figure, the second transfer opposing roller 064 and the drive roller 062 are arranged in a vertically long positional relationship in a vertically upward direction with respect to the transport path 4.
At the first transfer position 063 on the side face on the upstream side in the sheet transport direction.
And the second transfer position is at the lowest position.

The material of the intermediate transfer belt 051 is generally a seamless belt using a thin sheet of PET (polyethylene terephthalate), polycarbonate, ETFE (ethylene-tetrafluoroethylene copolymer) or the like. The surface is subjected to a fluorine coating treatment or the like so that the toner is not stuck.
The material of the first transfer roller 063 is a material obtained by adding lithium perchlorate to a polyurethane elastomer, a material obtained by adding lithium perchlorate to a polyester elastomer, and a conductive carbon black to urethane rubber around a shaft core such as aluminum. All of them have volume resistance of 10
^{4 ~10 5 Ω} · cm, use those provided with the elastic layer about Asker C hardness 50 to 80 °. Aluminum Roller with Shaft Core The second transfer facing roller 064 uses an aluminum shaft. The belt cleaner scrapes the toner remaining on the intermediate transfer belt 051 with a blade pressed against the belt surface.

The material of the second transfer roller 07 is the first transfer roller 07 described above.
As in the case of the transfer roller 063, a polyurethane elastomer added with lithium perchlorate, a polyester elastomer added with lithium perchlorate, and a urethane rubber added with conductive carbon black around the shaft core of aluminum or the like And so on, all have a volume resistance of 10 ⁴ to 1
0 ⁵ Ω · cm, use those provided with the elastic layer about Asker C hardness 50 to 80 °.

The flow of transfer from the image forming means to the intermediate transfer belt and from the intermediate transfer belt to paper will be described. At the first transfer position 055, the toner image formed on the photoconductor drum 051 is applied to the first transfer roller 063 by a voltage having a polarity opposite to that of the toner and an electric field generated using the photoconductor drum 051 as a counter electrode. Is transferred onto the transfer belt 061. At the second transfer position 057 with the rotation of the toner image on the transfer belt, the voltage applied to the second transfer roller 07 and having the opposite polarity to the toner and the second transfer opposing roller 0
The image is transferred onto the conveyed sheet by the electric field created by the 64. The photosensitive drum 051 and the transfer belt 061 are in contact with each other, and an appropriate nip is formed. The second transfer roller 07 and the second transfer opposing roller 064 are in contact or have a positional relationship of about 0.1 mm. As the voltage applied to the first transfer roller 063 and the second transfer roller 07, an appropriate voltage of about 1 to 6 kV is applied from a high-voltage transformer.

The fixing device 08 is composed of a heat roller 081, a fixing heater 0811, a pressure roller 082, and a guide plate 083. The fixing heater 0811 is built in, so that a predetermined temperature required for fixing is controlled. The pressure roller 082 is also formed by covering the periphery of a roller made of aluminum or the like having good thermal conductivity with an elastic layer made of heat-resistant urethane rubber and further having a release layer made of a fluorine-based resin such as PTFE on the outer periphery. Guide plate 083
Guides the leading edge of the conveyed paper toward the heat roller 081. Heat roller 081 and pressure roller 0
Reference numeral 82 is pressed by an appropriate pressure, and the paper having the unfixed toner transferred on its surface is nipped and pressed in the nip formed by the two rollers and is fixed. Here, the sheet on which the toner image is fixed is sequentially discharged to the discharge tray 10 by the discharge unit 09.

The discharge tray 10 will be described again with reference to FIG. Here, as in the fifth invention, a paper discharge tray lift means 101 is provided, and the paper discharge tray 10 can be raised and lowered as necessary. This is because, in the layout of the present case, the discharge position is low, so when the user takes the printed paper, it is difficult to take it in the low position.
After the last sheet of the job is discharged, it is lifted up to the position shown by the broken line in the figure. When the next job is entered and printing is started in a state where the printed sheet is not removed, control is performed so as to return to the original sheet discharge position again. Recently, many copying machines have a finisher. In this case, such a lifting means is not required.

[0044]

According to the first aspect of the present invention, the intermediate transfer belt unit is vertically disposed, the primary transfer is performed on the side of the intermediate transfer belt, and the secondary transfer is performed at the bottom of the intermediate transfer belt. By performing the operation at the position, the space for transferring the toner image to the sheet is shortened, the distance between the registration roller and the fixing unit can be reduced, and the sheet conveyance distance is shortened. In addition, by using a single paper cassette that is frequently used, and by making the paper feed position to the discharge substantially straight, the paper transport distance is further reduced and the transport path is not bent, so that jams can be reduced.

According to the second aspect of the present invention, the space can be further reduced by using the developing device of the vertical stirring means.

According to the third aspect of the present invention, since the toner container is laid out above the intermediate transfer belt and the developing device, the space formed by the toner container, the intermediate transfer belt, and the developing device becomes vertically long, so The transfer space for the toner image is shortened.

According to the fourth aspect of the present invention, since a plurality of simplified paper feed trays are used for feeding paper other than the main paper cassette, paper that is rarely used can be fed from here. Since a plurality of the simplified paper feed trays are prepared, it is possible to set a plurality of types other than the main paper. In the related art, even a sheet of less frequently used paper occupies one cassette, and the number of main paper sheets that are frequently used is limited because of the less frequently used paper. Was. For example, if the usage rate of the main sheet is 95%, 95% of the sheets that can be set in the entire copying machine may be the main sheet. That is, since the usage rate of the sheets other than the main sheet is less than a few percent of the whole, it is sufficient to feed the other sheets from the bypass at any time, which is more convenient for the user. Further, although the usage rate of the papers other than the main paper is low, since there are many types of each type (a small number of types), a plurality of simplified trays are provided. In conventional bypass paper feeding, 1
Although only the type of paper can be set, in this case, it is possible to set more types of paper in a smaller space by providing a plurality of bypasses that do not require much manufacturing cost than providing a plurality of cassettes. Further, since these simplified paper feed trays are located above the main paper feed cassette, the paper is conveyed from above to below, so that the slip of the conveyance rollers can be reduced and the occurrence of jams is reduced.

According to the fifth aspect of the present invention, since the sheet is conveyed from the top to the bottom, the sheet is discharged to the lower position. Therefore, this is compensated for by lifting the discharge tray. This is because, if a paper path is provided and the paper is discharged upward, paper that may be curled after fixing is conveyed from the bottom to the top. Discharged paper does not jam. If a large amount of paper is accumulated in the paper discharge tray, the paper can be lowered.

According to the sixth aspect of the invention, by using a large-capacity paper cassette for the paper cassette and incorporating the paper cassette in the main body of the image forming apparatus, the distance from paper feeding to paper discharging can be further reduced. . Furthermore, by using a drawer that can be pulled out over the entire surface, a space in the left-right direction is not taken up much. This is because the front loading system includes a special cassette, but the size is considerably large. If expensive but extremely stable paper feeding means such as air paper feeding is used for the large-capacity paper feeding cassette having only one, there is no doubt that a jam is further reduced.

As described above, by using an image forming apparatus having a new layout created by combining existing technologies such as the present invention, the number of jams is small, and even if a jam occurs, the conveying path is short. Therefore, it is possible to provide an image forming apparatus in which the location where a jam occurs can be easily specified and the processing can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 2 is a schematic diagram of a large capacity paper cassette and air feeding according to the present invention.

FIG. 3 illustrates an image forming unit, a transfer belt unit, and a transfer belt unit according to the present invention.
FIG. 5 is a schematic diagram of a second transfer roller and a fixing unit.

FIG. 4 is a schematic diagram of an image forming apparatus according to a related art <conventional example 1>.

FIG. 5 is a schematic diagram of an image forming apparatus according to a related art <conventional example 2>.

FIG. 6 is a schematic view of an image forming apparatus according to a related art <conventional example 2>.

[Explanation of symbols]

 01; large-capacity paper cassette 02; paper feeding means 03; registration roller pair 04; transport path 05; image forming means 051; photoconductor drum 052; main charging device 053; 055; first transfer position 056; drum cleaner 057; toner container 06; intermediate transfer belt (vertical) 061; belt 062; drive roller 063; first transfer roller 064; A second transfer roller 08; a fixing means 09; a discharge roller 10; a discharge tray 11, a simplified paper feed tray 111; a large size tray 112; a medium size tray 113; a small size tray 12; Digital optical system 22; automatic document feeder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/16 G03G 15/16 103 3F101 15/08 507 15/00 554 3F343 15/16 103 15/08 507Z F-term (reference) 2H032 AA05 BA09 BA19 BA23 2H071 BA03 BA29 BA41 DA08 DA09 DA12 DA15 DA22 EA04 2H072 BA03 BA12 BA13 CA01 CB03 CB09 FB10 2H077 AA12 AA15 AB02 AB03 AC02 AC03 AD02 AD06 AD13 AD18 AD10 AE02 A08 AC03 AC05 BA04 BD02 3F101 FB01 FE19 LA02 LA05 LA07 LB03 3F343 FA02 FB02 FB03 GA01 GB01 GC01 GD01 HA16 HA17 HD16 KB03 LA14

Claims (6)

[Claims] A sheet cassette capable of stacking a plurality of sheets;
Paper feeding means for feeding the paper one sheet at a time to the transport path, a pair of registration rollers for adjusting the leading edge of the transported paper and adjusting the timing, and forming a toner image on the photosensitive drum An electrophotographic image forming unit having a developing device having a developing roller, and a toner image formed by the image forming unit is transferred at a primary transfer position, and the toner image is transferred to a sheet at a secondary transfer position. In an image forming apparatus having an intermediate transfer belt, a fixing unit that fixes the sheet onto which the toner image has been transferred, and a discharge unit that discharges the sheet, the intermediate transfer belt is disposed vertically elongated substantially upward, The primary transfer is performed on the surface of the intermediate transfer belt that is substantially perpendicular to the horizontal transport path, the secondary transfer is performed at the lowermost position of the intermediate transfer belt,
An image forming apparatus, wherein a position of a pair of registration rollers, a position of a secondary transfer, a position of a fixing unit, and a position of a discharge unit are substantially linear. 2. The image forming means uses a vertical developing device in which a developing roller faces substantially upward of a photosensitive drum and a stirring means is arranged in a substantially vertical direction.
The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein a toner container is laid out above the developing device and the intermediate transfer belt. 4. An upper portion of the paper cassette has a plurality of simplified paper feed trays and a common single bypass conveyance path, and paper can be selectively fed from the plurality of simplified paper feed trays. 4. The apparatus according to claim 1, wherein the bypass conveyance path joins a position downstream of the paper feeding means of the large-capacity paper cassette and upstream of the pair of registration rollers in a conveying direction from an obliquely upward direction. Image forming device. 5. A discharge tray lifting means for lifting from a first discharge position for discharging the discharge tray to a second discharge position where a user can easily take out the discharged sheets. The image forming apparatus according to claim 1, further comprising: 6. An image forming apparatus according to claim 1, wherein said sheet cassette is capable of storing a large amount of sheets of paper, is built in the image forming apparatus main body, and can be pulled out to the front.