JPH02210379A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To use a shorter sheet, to reduce the number of parts and to simplify constitution by stretching a conveyer belt to a pressure roller and pushing the pressure roller to a heat roller via the conveyer belt. CONSTITUTION:The conveyer belt 41 is stretched to the pressure roller 42 which is pushed down to the heat roller 74 via the conveyer belt 41. The rotation of the pressure roller 42 drives the conveyer belt 41, which carries a having been transferred sheet 28 and leads it to a fixing means 33. The sheet is inserted between the heat roller 47 of the fixing means 33 and the pressure roller 42 together with the conveyer belt 41 to fix a transferred image on the sheet 28. Thus, a shorter sheet can be used, the number of parts can be reduced and the constitution can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to electronic devices such as laser printers, laser copying machines, and laser facsimiles that record images on paper using electrophotographic processes such as charging, writing, development, transfer, and fixing. Concerning photographic equipment.

Conventionally, in this type of electrophotographic apparatus, as shown in FIG. The image is transferred to the paper 2 using the steps shown in FIG. Then, it is guided by a guide plate 5 and sent to a fixing means 6,
There was one in which the transferred image was fixed by passing between the heat roller 7 and the pressure roller 8 of the fixing means 6.

However, this type of electrophotographic apparatus has a drawback that it is not possible to transport the paper 2 which is shorter than the distance from the transport roller pair 1 to the fixing means 6.

For this reason, some conventional electrophotographic devices, for example,
As shown in the figure, conveyance rollers 9 and 10 are arranged near each of the transfer means 4 and the fixing means 6, and
- There is one in which a conveyor belt 11 is stretched between 10 and 10, and the conveyor belt 11 sends the paper 2 after transfer to the fixing means 6.

However, this type of electrophotographic device also had its first problem.

■ Two conveyor rollers 9 and 10 along with the conveyor belt 11
, the number of parts increases.

(2) In order to drive the conveyance belt 11, it is necessary to provide a rotation transmission means for transmitting the driving force of the motor to rotate the conveyance roller 10, which makes the configuration complicated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such conventional problems in electrophotographic apparatuses, to enable the use of short sheets of paper, to reduce the number of parts, and to simplify the structure.

Therefore, in the present invention, an image on a photoreceptor 21 is transferred to a paper 28 by a transfer means 25, as shown in the illustrated embodiment below.
After the paper 28 is transferred to the fixing means 33 using the conveyor belt 41, the heat roller 4 of the fixing means 33
In an electrophotographic apparatus in which the transferred image is fixed by passing between It is characterized by being pressed against a roller 47.

Task - 1■ Then, the rotation of the pressure roller 42 drives the conveyor belt 41, and the conveyor belt 41 conveys the sheet 28 after transfer and guides it to the fixing means 33. The heat roller 47 and pressure roller 42 of the fixing means 33
The transferred image on the paper 28 is fixed through the gap between the paper 28 and the paper 28.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 shows a laser printer as an embodiment, and the reference numeral 20 in FIG. 1 shows the general structure of the internal mechanism of the laser printer. Inside the printer main body 2o, a belt-shaped photoreceptor 21 is provided approximately at the center.

A charging means 22, a writing means 23, a developing means 24, a transferring means 25, a neutralizing means 26, and a cleaning means 27 are arranged around the photoreceptor 21 in this order in the rotational direction (clockwise in the figure). Further, a paper feed tray 29 for storing paper 28 is removably loaded on the right side of the printer main body 20 in the figure.

The mounting portion of the paper feed tray 29 is provided with a paper feed section 32 having a calling roller 30, a pair of paper feed rollers 31, and the like. Further, the paper feed section 32 is provided with the above-described transfer means 25 in between.
A fixing means 33 is arranged on the opposite side. Then, the fixing means 33 communicates with the paper discharge tray 35 on the printer main body 20 through the paper discharge path 34. A pair of paper ejection rollers 36 is provided at the exit of the paper ejection path 34.

When the laser printer performs printing using an electrophotographic process, the paper 28 is sent out from the paper feed tray 29 by driving the calling roller 30. and,
It is transported by a pair of paper feed rollers 31.

Eventually, a registration sensor (not shown) detects the leading edge of the paper 28. However, the leading edge of the paper 28.

It hits the registration roller pair 37 and stops.

On the other hand, while rotating clockwise in the figure, the surface of the photoreceptor 21 is sequentially charged in a negative manner by a charging means 22, and then a laser beam is irradiated by a writing means 23 to form an electrostatic latent image on the surface. do. Subsequently, when passing through the developing means 24, the electrostatic latent image is successively visualized by toner, and a transferred image is formed on the surface of the photoreceptor 21.

Then, in synchronization with the transferred image, the paper 28 that had been in contact with the pair of registration rollers 37 mentioned above is moved onto the photoreceptor 2.
Send it towards 1. The transferred image on the photoreceptor 21 is then transferred onto the paper 28 by the transfer means 25. After the transfer, the charge remaining on the photoreceptor 21 is removed by the charge removing means 26, and the remaining toner is cleaned by the cleaning means 27.

On the other hand, the paper 28 is sent to a fixing means 33, and the transferred image is fixed by the fixing means 33. Thereafter, the recorded sheets 28 are sent out toward the paper ejection path 34 and ejected by the paper ejection roller pair 36 through the paper ejection path 34, and the recorded sheets 28 are sequentially stacked on the paper ejection receiver 35.

Incidentally, in the electrophotographic apparatus shown in FIG. 6, as shown in FIG. 1, a conveyance roller 40 is disposed near the transfer means 25 and supported rotatably. One side of the conveyor belt 41 is hung on the roller 40.

The conveyor belt 41 uses a heat-resistant material such as a polyester film with a thickness of about 0.2 cm as a base material, and coats the surface of the base material with a substance with good mold release properties such as fluororesin. It is formed endlessly with a width slightly wider than the maximum paper width. The other side of the conveyor belt 41 is applied to the outer periphery of the pressure roller 42 of the fixing means 33 . The pressure roller 42 is.

It is constructed by fixing a heat-resistant foam material 44 around a metal rod 43. Therefore, in the embodiment, the diameter of the central portion of the conveying roller 40 is slightly thicker than that of both ends, thereby preventing the conveying belt 41 from being biased to one side. In the illustrated embodiment, the proximal end is supported by a frame 45, and the tip of the blade 46 is pressed against the conveyor belt 41 to remove foreign matter adhering to the surface of the conveyor belt 41.

Then, as shown in FIG. 1, the pressure roller 42 is pressed against the heat roller 47 via the conveyor belt 41. As shown in FIG. 2, the heat roller 47 has a heater 48 at its center, and is supported at both ends by opposing side plates 50 (only one side plate 50 is shown in FIG. 2) via bearings 49. That is, on the side plate 50.

As shown in FIG. 4, a circular hole 51 and a rectangular hole 52 are formed vertically. Then, both ends of the heat rollers 47 are inserted into the corresponding circular holes 51 of the opposing side plates 50, and the second
As shown in the figure and FIG. 3, both are prevented from being removed by an E-ring 53. On the other hand, the corresponding rectangular hole 5 of the opposing side plate 50
2, both ends of the pressure roller 42 are inserted into each of them.

As shown in FIGS. 2 and 3, it is similarly prevented from being pulled out with an E-ring 54, and both ends are supported by opposing side plates 50 via bearings 55.

As shown in the figure, the pressure spring 56 is inserted between the bearing 55 and the lower edge 52a of the rectangular hole 52, and the bearing 55 is brought into contact with the upper edge 52b of the rectangular hole 52. As shown in FIG. 5, the pressure roller 42 is pressed against the heat roller 47 with a predetermined nip width N.

In FIG. 1, a reference numeral 57 indicates a separation claw that separates the fixed paper 28 from the heat roller 47.

Then, the rotation of the pressure roller 42 drives the conveyor belt 41, and the conveyor belt 41 conveys the sheet 28 after the transfer and guides it to the fixing means 33. Therefore, together with the conveyor belt 41, the heat roller 47 and pressure roller 42 of the fixing means 33
The transferred image on the paper 28 is fixed through the space between the paper 28 and the paper 28.

Effect of the invention Therefore, according to the present invention, there are the following effects.

■ Since the paper after transfer is sent to the fixing means using a conveyor belt, even short paper can be used.

- Since the number of conveyance rollers can be reduced by one compared to conventional electrophotographic devices that use conveyor belts, the number of parts can be reduced and costs can be reduced.

(2) Since the conveyor belt is passed around the pressure roller, the conveyor belt can be driven by the rotation of the pressure roller, and the configuration can be simplified without providing a separate means for transmitting rotation to the conveyor belt.

(2) Since the pressure roller is pressed against the heat roller via the conveyor belt, the hardness of the pressure roller can be made lower than before. Accordingly, in order to obtain a predetermined nip width in the fixing means, the diameter of the pressure roller can be small, and costs can be reduced. Furthermore, the pressing force of the pressure roller against the heat roller can be reduced, bearing loss torque can be reduced, drive torque can be reduced, and costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is an enlarged configuration diagram of the main parts of a laser printer that is an embodiment of the present invention, Fig. 2 is a sectional view of one end of the pressure roller and heat roller, and Fig. 3 is a left side view thereof. , 4th
The figure is a front view of a side plate used therein, FIG. 5 is an explanatory diagram showing the nip width between the pressure roller and the heat roller, and FIG. 6 is an overall schematic diagram of the internal mechanism of the laser printer. FIGS. 7 and 8 are partial configuration diagrams illustrating a conventional electrophotographic apparatus, respectively. 21...Photoreceptor 25...Transfer means 28...Paper 33...Fixing means 41... ...... Conveyor belt 42 ... Pressure roller 47 ... Heat roller Patent applicant stock

Claims (1)

[Claims] After the image on the photoreceptor is transferred to paper by a transfer means, the paper is sent to a fixing means using a conveyor belt, and the transferred image is fixed by passing it between a heat roller and a pressure roller of the fixing means. An electrophotographic apparatus, wherein the conveyor belt is stretched around the pressure roller, and the pressure roller is pressed against the heat roller via the conveyor belt.