JPH07115491B2 - Image forming device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an image forming apparatus using an electrophotographic system such as a laser beam printer.

(Prior Art) A laser beam printer (LBP) using a laser beam as a light source is known as an example of an image forming apparatus using an electrophotographic system capable of obtaining a high quality image. Printers are meeting the demands of consumers greatly due to miniaturization and cost reduction.

FIG. 8 shows the configuration of the laser beam printer. In the figure, 1 is a cassette for stacking and storing recording sheets,
2 is a paper feed roller for separating and feeding the recording sheets in the cassette 1 one by one, 3 is a registration roller for aligning the leading ends of the recording sheets, and 4 is a transfer for transferring an image on the recording sheets. Rollers 5, a fixing device for fixing an image on a recording sheet, and 6 a discharge tray for stacking the recorded recording sheets.

A process cartridge (not shown) is mounted on the main body of the laser beam printer, and the image signal is scanned by the laser scanner unit 7 and is flickered on the photosensitive drum (not shown) of the process cartridge by the laser beam. Exposed.

Here, the structure of the main body of the laser beam printer will be described. An optical stay 8, an optical auxiliary stay 9, a paper feeding stay 10 and a transfer / fixing stay 11 are provided between two side plates. Further, 12 is a guide, and after the opening / closing cover 13 is opened, a process cartridge (not shown) can be attached and detached along the guide 12. The process cartridge is configured as a unit that integrally includes a photosensitive drum, a cleaner, a developing device, and the like.

In the laser beam printer having the above configuration, since the optical system does not move during jam processing or process cartridge replacement, accuracy can be easily obtained and high rigidity can be ensured to improve image quality. In addition, the structure can be simplified, and the size and cost can be reduced.

(Problems to be Solved by the Invention) By the way, in recent years, printers have been required to have higher image quality and lower cost, and in order to meet these demands, the rigidity of the frame is improved and the cost of the frame is reduced. Must be configured.

However, since the side plate is conventionally provided with several stays, the optical stay 8 is used in the example shown in FIG.
There is a problem that the strength and rigidity with respect to the twisting are insufficient and the vibration of the laser scanner unit 7 easily affects the image.

Also, the torsional rigidity of the various frames 8, 9, 10 and 11 is not sufficient, and when the device is installed on a floor with poor flatness, the frames 8 to 11 are twisted and the laser beam irradiation position is displaced. There was also the problem that it was difficult to achieve high image quality.

The present invention has been made in view of the above problems, and an object thereof is to maintain a high frame rigidity of an optical support system to stably obtain a high-quality image, reduce the number of parts and reduce costs. An object of the present invention is to provide an image forming apparatus capable of achieving a heat insulation and ensuring a ventilation path for heat insulation.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a scanner unit for exposing a photosensitive member and a scanner unit holding a holding table which is fixed to both side plates of the apparatus body and holds the scanner unit. In an image forming apparatus having a heating / quantifying device provided on the side opposite to the surface side, the holding base is reinforced so that a space having a polygonal cross section is formed on the heating fixing unit side of the holding base. The holding base reinforcing member is provided, and the holding base reinforcing member is provided with ventilation holes so that a ventilation path connecting the heat fixing device and the outside of the apparatus main body is formed through the space having a polygonal cross section.

(Operation) According to the present invention, since the holder and the holder reinforcing member form a bag-shaped frame structure having a polygonal cross section, the rigidity of the holding system of the scanner unit is increased and its twisting is prevented. Therefore, a high quality image can be stably obtained.

Also, a space with a polygonal cross section is formed on the side of the heat fixing device of the holding table, and since this space is used as a ventilation path connecting the heat fixing device and the outside of the main body of the device, the heat transfer from the heat fixing device to the scanner unit. Is effectively prevented by the heat insulation effect of the air flow.

Furthermore, the space with a polygonal cross-section formed by the holding base and the holding base reinforcing member is also used as the space for the air passage connecting the heat fixing device and the outside of the main body of the device and the reinforcing space of the holding base, reducing the number of parts and cost. It is possible to downsize and downsize the device body.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of an image forming apparatus (laser beam printer) according to the present invention, and FIG. 2 is a perspective view showing the structure of an optical support system of the image forming apparatus. In these figures, FIG. The same elements as those shown are denoted by the same reference numerals, and description thereof will be omitted below.

In FIG. 1, reference numeral 15 is an optical system abutment for positioning the laser scanner unit 7, and 16 is an optical table reinforcement plate fixed to the optical system abutment 15 by screwing, spot welding or the like. The optical system base 15 and the optical base reinforcing plate 16 are firmly fixed to the side plates by screwing, caulking, spot welding or the like, and their widths are set equal to the distance between the side plates.

By the way, as shown in FIG. 2, the optical system support 15 is formed with an air discharge port 15a, and the optical base reinforcement plate 16 is formed with a plurality of air intake ports 16a (nine in the illustrated example). A duct 17 and a fan 18 are attached to the air outlet 15a.

When the fan 18 is rotationally driven, air between the process cartridge 14 and the fixing device 5 (see FIG. 1) is formed on the optical bench reinforcing plate 16 as indicated by an arrow A in FIG. The air inlet 16a flows into the closed space 19 having a triangular cross section formed between the optical system abutment 15 and the optical table reinforcing plate 16 and flows in the closed space 19 in the direction of the arrow B to support the optical system. The duct 17 and the fan 1 from the air exhaust port 15a formed in the base 15
It is discharged via arrow 8 in the direction of arrow D.

As described above, in the present embodiment, a bag-shaped frame structure is formed by the optical system abutment 15 and the optical table reinforcing plate 16, and the hermetically sealed structure formed between the optical system abutment 15 and the optical table reinforcing plate 16. Space 19
Is used as an air flow path, the heat from the fixing unit 5 receives heat from the laser scanner unit 7 due to the heat insulation effect of the air flow.
And the process cartridge 14 is effectively prevented from propagating to the side, and the laser scanner unit 7 and the process cartridge 14 are prevented from being adversely affected by heat.

Further, as described above, since the optical system abutment 15 and the optical table reinforcing plate 16 form a bag-shaped frame structure, their strength and rigidity are structurally increased, and their resistance to twisting is greatly increased. Enhanced resulting in higher quality images. According to the experiment, it is possible to obtain a sufficiently high torsional rigidity just by fixing an 80 mm x 30 mm square pipe-shaped one with a 1.6 mm thickness of iron plate between two iron plates of 400 mm x 300 mm size and 1.6 mm thickness. Was obtained. Therefore, it is possible to secure sufficiently high torsional rigidity without providing any other special stay, and the stay that has been required in the past is not necessary, so that the structure of the apparatus main body can be simplified and the cost can be reduced. .

Next, modified embodiments of the present invention are shown in FIGS. 3 to 7, respectively.

In the second embodiment shown in FIG. 3, the shape of the optical bench reinforcing plate 20 and the dimensions of the air suction port 20a are changed. That is, by constructing a bag-shaped frame structure having a rectangular cross section with the optical system support 15 and the optical base reinforcing plate 20, the second moment of area of the frame structure can be increased to further increase its torsional rigidity.
The air intake port 20a is small on the side close to the fan 18,
Each air intake by enlarging the side far from
The flow rate of air passing through 20a can be kept substantially constant.

In the third embodiment shown in FIG. 4, the side plates 21 and 22 are provided with air intake ports 21a and air exhaust ports 22a, respectively, and air is sucked into the closed space 19 from the outside of the apparatus body through the air intake ports 21a. As a result, the heat insulating effect of the fixing device and the optical system is further enhanced, and the fan 23 is arranged on the downstream side in the air flow direction in the closed space 19 to enhance the efficiency of exhaust heat.

In the above embodiment, the fans 18, 23 and the duct 17 are for exhaust, but they may be for intake.

Further, in the fourth embodiment shown in FIG. 5, the optical system abutment 24a and the optical base reinforcing plate 24b are formed by bending one sheet metal 24.
And are integrally configured, which makes it possible to further reduce the number of parts and reduce costs.

By the way, although the optical system does not move in the above-described embodiments, the present invention is also applicable to a so-called clamshell type structure.

The fifth embodiment shown in FIG. 6 is a type in which the upper frame unit 30 supporting the optical system is rotated around the shaft 28 to open it as shown when the jam is removed or the process cartridge 14 is replaced. An example in which the present invention is applied to the above laser beam printer is shown. In the figure, 25 is an optical system support for supporting the laser scanner unit 7, and 26 is an optical system support 25.
An optical stand reinforcing plate integrally fixed to the upper frame unit 30, and a side plate 27 of the upper frame unit 30.

Therefore, in this embodiment, as a result of the rigidity of the upper frame 30 being increased, even if the upper frame 30 is repeatedly opened and closed, the upper frame unit 30 or the optical system is unlikely to be deformed, and the position of the high optical axis is high. Accuracy is secured. Moreover, since the vicinity of the shaft 28 (center of rotation) of the upper frame unit 30 is reinforced, the upper frame unit 30 is roughly opened and closed to secure sufficient strength.

In the sixth embodiment shown in FIG. 7, the laser scanner unit 36 is arranged below the process cartridge 34 to irradiate the laser beam from the lower side. The laser beam unit 36 from below, and the optical plate reinforcing plate 38
Are fixed to the optical system base 37 integrally, and these optical base reinforcement plates
38 and the optical system abutment 37 constitute a bag-shaped frame structure, and the fixing device 35 is mounted on the optical table reinforcing plate 38.

Thus, in this embodiment, the same effect as described above can be obtained. However, in this embodiment, since the optical bench reinforcing plate 38 also serves as the fixing stay, the number of parts can be further reduced and the cost can be reduced.

(Effects of the Invention) As is apparent from the above description, according to the present invention, the scanner unit for exposing the photosensitive member and the scanner unit holding of the holding base fixed to both side plates of the apparatus main body for holding the scanner unit. In an image forming apparatus having a heat fixing device provided on the side opposite to the surface side, the holding base is reinforced so that a space having a polygonal cross section is formed on the heating fixing unit side of the holding base. The holding system of the scanner unit is provided because the holding table reinforcing member is provided, and the ventilation holes are provided in the holding table reinforcing member so that a ventilation path connecting the heating fixing device and the outside of the apparatus main body is formed through the space having the polygonal cross section. It is possible to obtain high quality images stably by increasing the rigidity of the device, reduce the number of parts, reduce the cost and downsize the device body, and secure the ventilation passage for heat insulation. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus (laser beam printer) according to a first embodiment of the present invention, FIG. 2 is a perspective view showing a configuration of an optical support system of the image forming apparatus, and FIG. 2 is a perspective view of an optical support system showing a second embodiment of the present invention, FIG. 4 is a perspective view of an optical support system showing a third embodiment of the present invention, and FIG. 5 is an image forming apparatus showing the fourth embodiment of the present invention. 6 is a sectional view of an image forming apparatus showing a fifth embodiment of the present invention, and FIG.
FIG. 9 is a sectional view of an image forming apparatus showing a sixth embodiment of the present invention,
FIG. 8 is a sectional view of a conventional image forming apparatus. 5,35 …… Fixer, 15,24a, 25,37 …… Optical abutment, 15a, 22
a …… Air outlet (vent), 16,20,24b, 26,38 …… Optical stand reinforcing plate (reinforcing member), 16a, 20a, 21a …… Air outlet (vent), 17 …… Duct (Ventilation path), 18,23 ... Fan, 19 ... closed space, 21,22 ... side plate.

Claims (1)

[Claims] 1. A scanner unit for exposing a photosensitive member, a holder fixed to both side plates of an apparatus main body for holding a scanner unit, and a holder unit provided on a surface opposite to a scanner unit holding surface side. In an image forming apparatus having a heating stationary unit, a holding base reinforcing member for reinforcing the holding base so that a space having a polygonal cross section is formed on the side of the heating fixing unit of the holding base. An image forming apparatus characterized in that a ventilation hole is provided in the holding base reinforcing member so that a ventilation path connecting the heat fixing device and the outside of the apparatus main body is formed through a polygonal space.