JPS61292166A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent modulation error of a semiconductor laser or blur of various mirror systems and lens systems by providing a light scanning unit on a partition wall between a light scanning unit and an electronic photograph recording device, and at the same time, forming an aperture facing a photosensitive drum on a partition wall between an entrance side of a thermal fixing device and the photosensitive drum. CONSTITUTION:Air sucked from an aperture 6 facing a photosensitive drum formed on a partition wall 5 between entrance side of a thermal fixing device 4 and the photosensitive drum 2 and an aperture 6' formed in the thermal fixing device 4 side is discharged to outside along the direction of carrying passage of transfer paper 3 passing through a specified space 7 between the partition wall 5 and a light scanning unit 10. Accordingly, adsorbing and cooling of ozone around the photosensitive drum, suction of heated air generated from the thermal fixing device and cooling of the light scanning unit 10 can be made by the same ventilation passage. Thus, the blur due to fluctuation of temperature of a semiconductor laser, a mirror system, a lens system and other various members in the light scanning unit 10 can be prevented perfectly.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to an optical scanning means for forming an electrostatic image while repeatedly scanning a laser beam on a photoreceptor using a rotating polygon mirror, and It relates to an image forming device consisting of an electrophotographic recording means that visualizes and transfers the image onto a transfer paper, and then fixes the image using a heat fixing device. The present invention relates to an image forming apparatus that can prevent heat diffusion.

"Prior Art" Conventionally, a laser beam oscillated by a semiconductor laser is incident on a rotating polygon mirror as parallel linear focused light through a first imaging lens system, and is deflected by a predetermined angle by rotation of the rotating polygon mirror. There is a well-known optical scanning means that forms a predetermined electrostatic latent image while scanning the photoreceptor drum after the image is converted into uniform motion by being incident on a second imaging lens system having an fθ characteristic without being reflected. In this type of optical scanning means, when fluctuations in ambient temperature or humidity occur, various mirror systems and lens systems become cloudy, making beam scanning and beam detection inaccurate. Furthermore, when the above-mentioned temperature fluctuation occurs, the Kerr current characteristics of the semiconductor laser change, and due to modulation errors in the laser beam emitted from the laser, it becomes impossible to form an optical dot pattern with accurate pitch intervals. First, rotational fluctuations occur in the synchronous motor connected to the rotating polygon mirror, making it impossible to synchronize with the rotational speed of the photoreceptor drum, resulting in various problems such as jitter. For this reason, it has been proposed that the optical scanning means is equipped with a ventilation fan (Utility Model Application No. 55-1
111548).

On the other hand, such optical scanning means is generally incorporated into an electrostatic recording device based on a known electrophotographic recording method to form a predetermined image. Since a thermal fixing device for thermally fixing the image is incorporated, the heat from the thermal fixing device is likely to be transmitted to the photosensitive drum, and a means to prevent this is naturally required.

However, in the above-mentioned utility model, the electrophotographic recording means such as the fixing device is closed off by a partition wall, and no consideration is given to preventing heat propagation to the drum.

In particular, in an image forming apparatus having such a configuration, in order to downsize the apparatus and secure a toner storage capacity used for development, the optical scanning means is formed into a unit, and the unit is arranged in a free space above the heat fixing device. In many cases, in an apparatus having such a configuration, it is necessary to provide a means for preventing heat propagation between the heat fixing device, the photoreceptor drum, and the optical scanning unit.
This is an extremely important element in putting this device into practical use.

On the other hand, there has been no technology to completely isolate heat between the thermal fixing device and the optical scanning unit, but a technique to prevent heat diffusion in the thermal fixing device while slightly cooling the synchronous motor connected to the rotating polygon mirror. only exists. (Unexamined Japanese Patent Publication No. 59-
No. 55487) Figures 3 and 4 show an example of such prior art. To briefly explain its structure, a photosensitive drum 101 is surrounded by a developing device 102 and other various peripheral devices necessary for performing electrophotographic formation.

On the other hand, a thermal fixing device 104 is disposed near the side wall 103 of the apparatus on the downstream side of the transfer paper conveyance path, and is configured to eject the transfer paper onto which the toner image has been transferred, after heat fixing, to the outside.

Furthermore, an optical scanning unit 110 is disposed in the spare space on the side of the heat fixing device 104-L, covering almost the entire width in the longitudinal direction of the device.

The optical scanning unit) 110 is constructed by arranging a rotating polygon mirror 111 and other various scanning members at predetermined positions on the substrate m. It is placed directly above.

Therefore, in this prior art, since the heat from the heat fixing device 10g14 is directly transferred to the synchronous motor 13', the synchronous motor is surrounded by a partition wall 114, An exhaust fan 115 is provided on the rear side plate side of the partition wall 114, and an exhaust fan 115 is provided on the side of the front cover 118 of the apparatus (see FIG. 4) or the fixing roller 105 of the heat fixing device 104.
Each suction port 1 is arranged in a slit shape along the axis (see Figure 3).
1? a and 117b, and is configured to discharge the heated air propagated by the heat fixing device 104 to the outside.

"Problem to be Solved by the Invention" However, according to the prior art, the heat fixing port 11?
a. 11? The heated air on the heat fixing device 104 on the opposite side where b is formed is blocked by the air curtain formed by the suction port 117b, and is not propagated to other parts, rather than being transmitted to other optical scanning unit members other than the motor, for example, not shown. This tends to cause modulation errors in the laser beam propagated to the periphery of the semiconductor laser and oscillated by the laser.

Further, in the prior art, for example, in the technology shown in FIG.
Therefore, the ventilation direction of the air flowing inside the partition wall 114 is parallel to the axis of the fixing roller 105, and in the technique shown in FIG. In any case, almost no air remaining near the photoreceptor drum 101 can be sucked.

As a result, toner powder and other dust generated during the development, transfer, and cleaning steps remain around the photoreceptor drum 1O1, enter the optical scanning unit 110, and cause damage to the mirror system and lenses in the unit 110. It may contaminate the system.

Similarly, the ozone concentration generated by the transfer device and charger disposed around the photoreceptor drum 101 increases, and the ozone leaks out to the outside, which may have an adverse effect on the human body.

In view of the drawbacks of the prior art, the present invention prevents the heat propagation of the heated air generated from the heat fixing device toward the photoreceptor drum side, exhausts the heated air, and directs the air around the photoreceptor drum to the optical scanning unit. An object of the present invention is to provide an image forming apparatus in which an optical scanning unit is also cooled by passing between an optical scanning unit and a partition wall, and heat propagation from a thermal fixing device can be effectively prevented.

Another object of the present invention is to provide an image forming apparatus that can promptly discharge dust and the like generated near the photoreceptor drum to the outside and that prevents the dust from entering the optical scanning unit at all. be.

Furthermore, another object of the present invention is to adsorb ozone during the suction of cooling air on the photoreceptor drum side, to prevent ozone from stagnating in the vicinity of the photoreceptor drum, and to prevent the ozone from being removed from the outside. An object of the present invention is to provide an image forming apparatus that can prevent the image from being ejected.

"Means for Solving Problems" In order to achieve such technical problems, the present invention solves, for example, the first problem.
As shown in the figure, the laser beam L is
an optical scanning means A that forms an electrostatic image while repeatedly scanning the image on the photoreceptor drum 2;
In an image forming apparatus comprising an electrophotographic recording means B, the image is fixed by a thermal fixing device 4 after the image is transferred to the image forming apparatus. Partition wall 5-
1: An optical scanning unit 1O is disposed in , and an opening 6 is formed at an arbitrary location on the partition wall 5 between the photoreceptor drums 2 from the entrance side of the heat fixing device 4 so as to face the photoreceptor drum 2. While the air sucked through the opening 6 passes through the predetermined space 7 between the partition wall 5 formed above the heat fixing device 4 and the optical scanning unit 10 along the transfer direction of the transfer paper 3, Proposes a technical means configured to discharge to the outside,
In a particularly preferred embodiment, an ozone filter 8 is preferably installed in the opening 8.

Similarly, 6° is an opening formed at an arbitrary location of the partition wall 5 facing the heat fixing device 4, and the heated air generated around the heat fixing device 4 is prevented from propagating toward the photoreceptor drum 2 side, and the space 7 is deflected. It is intended for suction.

Note that an ozone filter 8' (shown in phantom lines) may be attached to the opening 8' as well.

Furthermore, since the air passing through the space 7 is mainly air sucked from the vicinity of the photoreceptor drum 2, the frame 11 of the optical scanning unit 10 may be formed of aluminum or other metallic material; Since a portion of the heated air heated by the heat fixing device 4 is also sucked, it is preferable to use a material with poor thermal conductivity, such as a plastic material that can be precisely processed.

"Operation" According to this technical means, an opening θ formed in the partition wall 5 between the inlet side of the heat fixing device 4 and the photoconductor drum 2 so as to face the photoconductor drum 2, and an opening θ formed on the heat fixing device 4 side. The air sucked through the formed opening 6' is configured to be discharged to the outside while passing through a predetermined space 7 between the partition wall 5 and the optical scanning unit 10 along the transfer path direction of the transfer paper 3. Therefore, the optical scanning unit can be cooled in the same ventilation path in conjunction with ozone adsorption and cooling around the photoreceptor drum 2 and suction of heated air generated from the heat fixing device 4, reducing the need for ventilation means. .

As a result, it is possible to completely prevent fogging caused by temperature fluctuations of the semiconductor laser 12, mirror system, lens system, and other various members in the optical scanning unit IO.

Furthermore, the synchronous motor 13 exposed on the bottom side of the optical scanning unit 10 can also compensate for steady rotation without causing a temperature rise.

Further, according to this technical means, since the opening 6 is formed in the partition wall 5 between the photoreceptor drums 2 from the entrance side of the heat fixing device 4, facing the photoreceptor drum 2, the opening 6 is 6, the dust generated near the photoreceptor drum 2 can be quickly sucked up and discharged to the outside, and since the optical scanning unit 1O has a closed structure, these dust can be There is no fear of intrusion into the unit 10 at all.

Furthermore, according to the present technical means, by attaching the ozone filter 8 to the opening 8, ozone is adsorbed while the cooling air on the photoreceptor drum 2 side is being sucked, and the ozone filter 8 is attached to the opening 8.
It is possible to prevent ozone derived from the vicinity from stagnation and to completely prevent the ozone from being discharged to the outside.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. It's nothing more than that.

1 and 2 are front sectional views showing an image forming apparatus according to an embodiment of the present invention. First, the schematic structure thereof will be explained. The photosensitive drum 2 is arranged approximately in the center of the apparatus, and A light scanning unit 10, a developing unit 21 that visualizes the electrostatic latent image, a transfer device 22 that transfers the visualized electrostatic image onto the transfer paper 3, and a toner remaining after the transfer. A cleaning member 38 for removal, a static elimination lamp 23 for erasing residual charges on the surface, and a charger 24 for uniformly charging the surface of the photosensitive drum 2 in preparation for the next exposure are arranged. Paper feed cassette 25, M
Paper roller 2B, registration roller 27, conveyance guide 28,
A thermal fixing device 4 and the like are arranged so that the toner image formed on the photosensitive drum 2 by a known electrophotographic printing method is transferred and fixed onto the transfer paper 3, and then discharged to the outside. Further, 28 is a drive motor that rotates the photosensitive drum 2 and other rotating members.

Now, above the photoreceptor drum 2, a partition wall 5 for positioning and fixing the optical scanning unit 10 at a predetermined position is provided. a wall portion 51 and a vertical wall portion 54 provided on the paper discharge side;
It consists of a horizontal wall portion 52 extending in the direction of the heat fixing device 4 through an opening 6 having a sloped step shape and an opening B° formed at an arbitrary location facing the upper portion of the transfer paper entrance side of the heat fixing device 4; It is fixed to the device housing 30 at one end of the vertical wall portions 51,54.

The horizontal wall portion 52 has a slit opening 55 formed at a position directly above the generatrix line of the photoreceptor drum 2 so that the scanning beam L can be incident on the photoreceptor generatrix line, and is located on the downstream side of the inclined step-shaped opening 8, i.e. The straight-L portion of the heat fixing device 4 is horizontally extended to form a predetermined space 7 between the horizontal wall portion 52 and the optical scanning unit 10 .

The predetermined space 7 has a width slightly larger than the height of the synchronous motor 13 attached to the bottom of the optical scanning unit 10, and is configured so that the synchronous motor 13 does not come into contact with the horizontal wall portion 52.

Further, a sponge-like water droplet absorbing material 31 is attached to the lower surface of the horizontal wall portion 52 directly above the heat fixing device 4 1, and a transfer paper 3
When water vapor generated from the water vapor is condensed on the horizontal wall portion 52, it is absorbed by the water droplet absorbing material 31 to prevent problems caused by adhesion and falling of water droplets. The water absorbed by the water droplet absorbing material 31 is successively evaporated by heating by the heat fixing device 4.

On the other hand, an ozone filter 8 is attached to the predetermined space side of the opening section 6, and a vertical wall section 25 located on the paper discharge side.
Paired air blowers 32 and 33 are arranged on both sides of the optical scanning unit IO inside the optical scanning unit 4 (see FIG. 2).

Note that the air blower may be installed in such a way that the ventilation path is the same as the axial direction of the fixing roller; in this case, the housing 3
The ventilation hole formed at 0 is on the back side of the device.

As a result, due to the rotation of the air blowers 32 and 33 during the recording operation, the internal air around the photosensitive drum 2 is sucked into the predetermined space 7 from the opening 8 through the ozone filter 8, and the optical scanning unit) Ozone generated near the photoreceptor drum 2 due to corona discharge from the charger 24 and the like is attached to the opening 6 and is discharged from the apparatus while passing around the synchronous motor 13 sandwiched between the synchronous motor 13 and the horizontal wall 52. The ozone is easily adsorbed by the ozone filter 8 and can prevent ozone harmful to the human body from being discharged to the outside.

The ventilation by the blowers 32 and 33 is provided by the synchronous motor 13.
At the same time as cooling, the heated air generated by the heat fixing device is sucked through the opening 8°, and is ventilated in the predetermined space 7 and discharged without being propagated to the photosensitive drum 2 side. As a result, steady rotation of the synchronous motor 13 is guaranteed, and errors due to temperature fluctuations of the semiconductor laser 12 disposed in the optical scanning unit 10 are prevented, and fogging etc. due to temperature fluctuations of various mirror systems in the optical scanning unit 10 are prevented. can be prevented.

Next, the configuration of the optical scanning unit 10 will be explained in detail.

11 is a frame body for assembling various parts of the optical scanning system in predetermined positions;
A frame main body 111 made of precision moldable plastic resin and having a side wall 111a erected around the frame main body 111, an upper cover 112 that hides the frame main body 111, and a reflective mirror 1.
4.15 It has a closed structure with the side plate 113 arranged on the mounting side.

Next, the arrangement relationships of various members assembled to the frame will be explained.

View of the frame body 111 - L left side (position directly above the heat fuser reef)
There is a rotating polygon mirror 1B connected to a synchronous motor 13, and a semiconductor laser 12 and a cylindrical lens 17 are positioned and fixed in a mounting passage 114 located on the side thereof in order from the open end side. - After converging the modulated beam L emitted from the beam L into a linear spot light parallel to the scanning direction, the modulated beam L is converged as a linear spot light parallel to the scanning direction, and then the beam L is focused at a rotating polygonal surface at a predetermined angle via the deflection mirror 18 disposed on the exit side of the mounting passage 114. Mirror 1
The beam is incident and imaged on the deflection plane of B.

The rotating polygon mirror 1B rotates in synchronization with the photoreceptor drum 2 by a synchronous motor 13, and sweeps the modulated beam L in the main scanning direction while outputting it from the rotating polygon mirror 16 as a scanning beam L that moves at a constant angular velocity in a fan shape. fθ lens system placed on the side
Inject it into the

After converting the scanning beam L into a constant velocity interlocking beam using the fθ lens system 1, the scanning beam L is made incident on the toroidal lens 18 via the reflection mirror 14.15, and after correcting the surface tilt of the rotating polygon mirror 1B, the slit aperture 111b, 55, the frame body 111 slit opening 1 on the exit side of the toroidal lens 19
A filter 38 is interposed in the portion 11b to prevent dust from entering the optical scanning unit 10.

On the other hand, a detection mirror 37 is located on the scanning beam L scanning start side on the exit side of the fθ lens system L, and a photodiode 38 is located outside the scanning area facing the detection mirror 37.
are arranged respectively, and each time the scanning beam L is repeatedly scanned by the rotating polygon mirror 1B, it is guided to the photodiode 38 via the detection mirror 37, and is configured to output a reference signal for regulating the modulation start timing of the scanning beam L. .

As described above, the optical scanning unit 10 has a closed structure with the frame body 11, and the front surface of the frame body 111 is exposed by opening the upper cover 112, so that it is easy to replace and adjust the various members. Repairs can be made.

``Effects of the Invention'' As described above, according to the present invention, the predetermined space formed between the optical scanning unit and the heat fixing device is used as a ventilation passage, and the air from the photoreceptor drum side is sucked, and the air is removed from the heat fixing device. Because the heated air can be discharged to the outside without heat propagating to the drum side, there is no temperature fluctuation within the unit, and there is no possibility of modulation errors in the semiconductor laser or fogging of various mirror systems and lens systems. Furthermore, it ensures steady rotation of the synchronous motor connected to the rotating polygon mirror, and as a result, the photoreceptor drum -
According to the present invention, it is possible to form a clear image without causing any pitch deviation or jitter in the optical dot pattern formed on the L.Furthermore, according to the present invention, dust generated near the photoreceptor drum can be promptly discharged to the outside. At the same time, these particles do not enter the optical scanning unit at all, and various problems such as poor control and reduction in image clarity caused by the adhesion of these dust particles can be prevented.

Furthermore, according to the present invention, an ozone filter is interposed during suction of the cooling air on the photoreceptor drum side, thereby adsorbing ozone generated near the photoreceptor drum and preventing the ozone from being discharged to the outside. I can do it. It has various effects such as

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a plan cross-sectional view of an optical scanning unit, and FIG. Figure 4 is an enlarged view of the main part with some modifications.

Claims (1)

[Scope of Claims] 1) Optical scanning means for forming an electrostatic image while repeatedly scanning a laser beam on a photosensitive drum using a rotating polygon mirror, and visualizing the electrostatic image and transferring it to a transfer paper. After that, in an image forming apparatus consisting of an electrophotographic recording means that fixes the image by a thermal fixing device, the optical scanning means is unitized to form a closed structure, and a partition wall that partitions the optical scanning unit and the electrophotographic recording means is provided. Along with arranging the optical scanning unit,
An opening is formed on the side of the partition wall facing the photosensitive drum and the side facing the heat fixing device, and air sucked through the opening is formed above the heat fixing device between the partition wall and the optical scanning unit. An image forming apparatus characterized in that the image forming apparatus is configured to be discharged to the outside while passing through a predetermined space of the image forming apparatus. 2) An image forming apparatus according to claim 1, wherein an ozone filter is attached to an opening facing the photosensitive drum. 3) A patent in which the frame of the optical scanning unit is formed of a material with poor thermal conductivity. Image forming apparatus according to claim 1 or 2.