JP2002149017A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing dust and toner from sticking to a sealing glass, which covers a laser beam exit aperture of a raster scanning unit, during an image forming operation and a stand-by period, and capable of reducing noise due to rotation of a blowing fan. SOLUTION: An optical path chamber for the passage of a laser beam is formed between an image forming engine and the raster scanning unit. On the other hand, in the optical path chamber, a shutter member is provided. The shutter member is capable of dividing the optical path chamber into two by properly projecting the shutter member into the optical path of the laser beam. Further, of the optical path chambers divided in two by the shutter member, the first optical path chamber positioned on the raster scanning unit side is provided with a blowing duct, which sends air into the first optical path chamber. To the contrary, the second optical path chamber positioned on the image forming engine side is provided with an exhaust duct, which expels the air from the second optical path chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a laser beam printer.
The present invention relates to an improvement in an image forming apparatus that forms a recorded image according to image information by exposing a photosensitive drum with a laser beam emitted from a raster scanning unit.

[0002]

2. Description of the Related Art Heretofore, after a photosensitive drum has been exposed to a laser beam emitted from a raster scanning unit, an electrostatic latent image formed on the photosensitive drum by the exposure has been developed with toner and developed. A so-called laser beam printer that forms a recording image according to image information by transferring a toner image onto a recording sheet is known. In the raster scanning unit, a laser light source that emits a laser beam modulated by image information, and scans the laser beam emitted from the laser light source along the axial direction of the photosensitive drum (hereinafter, referred to as “main scanning direction”). A polygon mirror and the like are provided. A laser beam scanned by a polygon mirror that rotates at high speed is refracted and reflected by a plurality of lenses and mirrors, and then a slit-shaped irradiation port provided in a housing of a raster scanning unit. And reaches the photosensitive drum.

[0003] In order to prevent dust and toner from entering the raster scanning unit, which is a precision optical device, usually,
The irradiation port is sealed by a seal glass, and the laser beam is irradiated on the photosensitive drum through the seal glass. However, if dust or toner adheres to the seal glass, the laser beam scanned in the main scanning direction will be blocked at a specific position on the seal glass, and the recorded image will appear in the rotation direction of the photosensitive drum (hereinafter referred to as the rotation direction). ,
White streaks along the “sub-scanning direction”) occur. Such adhesion of dust or toner to the seal glass is likely to occur, for example, when a photosensitive drum or a developing device made into a cartridge is attached to or detached from an image forming apparatus. It is also caused by leaking from Further, in recent years, the size of a laser beam printer has been reduced to a tabletop, and there has been a case where a raster scanning unit has to be arranged below a developing device due to an in-machine layout for achieving such size reduction. In such a case, the toner may unintentionally drop from the developing device onto the seal glass.

For this reason, in a laser beam printer disclosed in Japanese Patent Application Laid-Open Nos. 2-121748 and 3-92651, an air flow from a laser beam irradiation port to a photosensitive drum is formed in an optical path of a laser beam. The formed air flow prevents dust and toner floating in the atmosphere in the printer from adhering to the seal glass.

[0005]

However, in order to form the above-mentioned air flow between the raster scanning unit and the photosensitive drum, a blowing fan for sucking air from outside the printer is rotated. During the image forming operation, the main motor for driving the photosensitive drum, the developing device, and the like is rotating, so the sound of the blower fan is not so disturbing, but the main motor stops. During the standby, there is a problem that the rotation sound of the blower fan is unpleasant. On the other hand, it is actually practiced to stop the blower fan during standby, but in that case, there is a disadvantage that dust and toner floating in the atmosphere inside the apparatus easily adhere to the seal glass of the raster scanning unit.

At the time of standby when the developing device is stopped,
Although it is thought that there is little floating toner around the photoconductor drum, it is difficult to completely seal both ends of the photoconductor drum in the axial direction with respect to a fixed portion such as a housing. Also, there is a concern that dust entering through the gap between the photosensitive drum and the fixing portion may adhere to the seal glass.

Further, when the photosensitive drum and the developing device are replaced, when these are pulled out of the printer,
In some cases, the atmosphere in front of the seal glass is released to the atmosphere outside the printer, and there is a disadvantage that dust and toner easily adhere to the seal glass when replacing the drum cartridge or the developing cartridge.

The present invention has been made in view of such a problem, and an object thereof is to provide a seal glass covering a laser beam emission port of a raster scanning unit in both an image forming operation and a standby state. An object of the present invention is to provide an image forming apparatus that can prevent dust and toner from adhering and reduce noise caused by rotation of a blowing fan.

Another object of the present invention is to prevent dust or the like from entering the inside of the apparatus from outside the apparatus even when the developing cartridge or the drum cartridge is replaced, and thus the seal glass of the raster scanning unit can be removed. An object of the present invention is to provide an image forming apparatus capable of preventing dust from adhering.

[0010]

In order to achieve the above object, the present invention provides a raster scanning unit which emits a laser beam modulated by image information, and a photosensitive drum which is exposed by the laser beam. An image forming engine that forms a toner image corresponding to image information; and an image forming apparatus that transfers a toner image formed by the image forming engine to a recording sheet to form a recorded image. It provides two technical means.

That is, a first technical means is that a pair of optical path forming plates are provided between the image forming engine and the raster scanning unit in parallel with the axial direction of the photosensitive drum with the optical path of the laser beam interposed therebetween. Provided, while forming an optical path chamber through which the laser beam passes by these optical path forming plates, a shutter member capable of bisecting the optical path chamber by appropriately entering the optical path is provided in the optical path chamber,
Further, among the optical path chambers divided by the shutter member, the first optical path chamber located on the raster scanning unit side is provided with a blower duct for feeding air to the optical path chamber, while the first optical path chamber is located on the image forming engine side. The two optical path chambers are provided with an exhaust duct for discharging air from the optical path chamber.

According to such a technical means, it is possible to expose the photosensitive drum with the laser beam by retracting the shutter member during the image forming operation, and at the same time, to the first optical path chamber on the raster scanning unit side. Since the second optical path chamber on the photosensitive drum side is communicated with the second optical path chamber, when an air flow is sent from the air duct to the first optical path chamber, the air flow flows through the second optical path chamber to the exhaust duct, and raster scanning is performed. It is possible to form an air flow from the unit to the photosensitive drum. Further, at the time of standby when the exposure of the photosensitive drum is not performed, the shutter member is advanced to separate the first optical path chamber from the second optical path chamber, and in that state, an air flow is sent to the first optical path chamber. Such an air flow blows out from the gap between the shutter member and the optical path forming plate into the second optical path chamber. At this time, since the gap between the shutter member and the optical path forming plate is extremely small, even if the amount of air blown to the first optical path chamber is extremely small, air is rushed from the gap between the shutter member and the optical path forming plate. As a result, dust and toner can be effectively prevented from entering the first optical path chamber from the second optical path chamber through the gap. That is, it is possible to reduce the amount of air to be blown in the standby mode compared to the operation, and to reduce the power consumption and noise of the blowing fan in the standby mode.

On the other hand, a second technical means is that a pair of optical path forming plates are provided between the image forming engine and the raster scanning unit in parallel with the axial direction of the photosensitive drum with the optical path of the laser beam interposed therebetween. Provided, while forming an optical path chamber through which the laser beam passes by these optical path forming plates, a shutter member capable of bisecting the optical path chamber by appropriately entering the optical path is provided in the optical path chamber, Further, of the two optical path chambers divided by the shutter member, the second optical path chamber located on the side of the image forming engine is provided with a blower duct for feeding air to the optical path chamber, and exhaust air for discharging air from the optical path chamber. A duct is provided to retract the shutter member during exposure of the photoconductor drum by a laser beam to communicate the first optical path chamber and the second optical path chamber, while the photoconductor drum is exposed. The time of exposure is characterized in that it has configured to close the opening of the exhaust duct in the shutter member with separating the first optical path chamber and the second optical path chamber is advanced to the shutter member.

According to such technical means, the shutter member separates the first optical path chamber from the second optical path chamber during standby when the exposure of the photosensitive drum is not performed, and the exhaust member opened to the second duct. Since the duct is closed, the second
The air flow blown into the optical path chamber loses its destination and blows out from the gap between the axial ends of the photosensitive drum and a fixed portion such as a housing. At this time, the gaps at both ends of the photosensitive drum in the axial direction are extremely small.
Even if the amount of air blown into the optical path chamber is extremely small, air will be blown out vigorously from the gap, making it possible to effectively prevent dust from entering the second optical path chamber through the gap. Become. That is, similarly to the first technical means, it is possible to reduce the amount of air to be blown at the time of standby compared to the time of operation, and to reduce power consumption and noise of the blower fan at the time of standby.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the configuration of a tandem type color laser beam printer to which the present invention is applied. This laser beam printer includes four image forming engines 10Y, 10M, 10M that form toner images for each color of yellow, magenta, cyan, and black.
C, 10Bk, and an intermediate transfer belt (IBT) 20 on which a toner image is primarily transferred from each image forming engine. The toner image multiplex-transferred onto the intermediate transfer belt 20 is secondarily transferred onto a recording sheet P. To form a full-color image.

The intermediate transfer belt 20 is formed endlessly and wrapped around a pair of belt transport rollers 21 and 22. The intermediate transfer belt 20 is rotated by arrows in the direction of the arrow to be rotated by the respective color imaging engines 10Y, 10M, 10C and 10Bk. It is configured to receive primary transfer of the formed toner image. Further, one of the belt transport rollers 21 with the intermediate transfer belt 20 interposed therebetween.
A recording sheet P is inserted between the transfer roller 30 and the intermediate transfer belt 20 that are in pressure contact with each other, and the toner image is transferred from the intermediate transfer belt 20 to the secondary transfer roller 30. It is designed to receive secondary transfer. That is, the belt transport roller 21 functions as a backup roller of the transfer roller 30. On the other hand, a belt cleaner 23 of the intermediate transfer belt 30 is provided at a position facing the belt transport roller 22 located on the opposite side, and the toner remaining on the intermediate transfer belt 20 after the secondary transfer is removed on the intermediate transfer belt 20. Is configured to be removed from.

Below the intermediate transfer belt 20, the four image forming engines 10Y, 10M, 10C and 10B described above are provided.
k are arranged in parallel so that a toner image formed according to image information of each color is primarily transferred to the intermediate transfer belt 20. These four image forming engines are arranged in the order of yellow 10Y, magenta 10M, cyan 10C, and black 10Bk along the rotation direction of the intermediate transfer belt 20, and form the black image which will be used most frequently. The image engine 10Bk is arranged closest to the secondary transfer position. In addition, these image forming engines 10Y, 10Y
Below the M, 10C, and 10Bk, a raster scanning unit 40 that exposes the photosensitive drum 11 provided in each image forming engine in accordance with image information is provided. The raster scanning unit 40 includes all image forming engines 10Y, 10M,
Four semiconductor lasers (not shown) that emit a laser beam Bm modulated according to image information of each color and are shared by 10C and 10Bk, and these four laser beams Bm are rotated at a high speed and a photoconductor is used. A polygon mirror 41 that scans along the axial direction of the drum 11; Each laser beam Bm scanned by the polygon mirror 41 travels along a predetermined path while being reflected by a mirror (not shown), and then passes through each of the image forming engines through an irradiation port 42 provided above the raster scanning unit 40. 10
The Y, 10M, 10C, and 10Bk photosensitive drums 11 are exposed.

Each of the image forming engines 10Y, 10M, 1
Reference characters 0C and 10Bk denote a photosensitive drum 11, a charging roller 12 for charging the photosensitive drum 11 to a uniform background potential, and an electrostatic roller formed on the photosensitive drum 11 by exposure to the laser beam Bm. A developing unit 13 for developing a latent image to form a toner image;
And a drum cleaner 14 for removing residual toner and paper dust from the surface of the photosensitive drum 11 after the transfer to 0.
It is configured such that a toner image corresponding to image information of each color can be formed on the photosensitive drum 11. The developing device 13 is of a type using a two-component developer in which a toner and a carrier are mixed. In order to omit maintenance of replacement of the developer due to aging, the toner and the carrier are supplied from a replenishment cartridge (not shown). A so-called trickle developing method of replenishing the mixed developer and automatically discharging the deteriorated developer is used.

Each of the image forming engines 10Y, 10M, 10C,
The primary transfer roller 15 is positioned at a position facing the photoconductor drum 11 of 10 Bk so as to sandwich the intermediate transfer belt 20.
Y, 15M, 15C, and 15Bk are provided. By applying a predetermined transfer bias voltage to the transfer rollers 15Y, 15M, 15C, and 15Bk, the photosensitive drum 11 and the transfer rollers 15Y, 15M, and 15C are applied. , 1
5Bk, an electric field is formed, and the charged toner image on the photosensitive drum 11 is transferred to the intermediate transfer belt 20 by Coulomb force.

On the other hand, the recording sheet P is transferred from the paper feed cassette 2 stored in the lower portion of the printer housing 1 to the inside of the printer, specifically, to a secondary transfer position where the intermediate transfer belt 20 and the secondary transfer roller 30 are in contact. Supplied. Paper feed cassette 2
Is configured to be set by being pushed into the lower portion of the printer housing 1 from the front side of the printer housing (the front side in FIG. 1), and the upper portion of the set paper feed cassette 2 is inserted into the cassette 2. A pickup roller 24 and a paper feed roller 251 for pulling out the stored recording sheet P are provided side by side. Further, a retard roller 26 for preventing double feeding of the recording sheet P is provided at a position facing the paper feed roller 25.

The transport path 27 for the recording sheet P inside the printer is provided substantially vertically along the left side surface of the printer housing 1, and is drawn out of the paper feed cassette 2 located at the bottom of the printer housing 1. The recording sheet P rises along the sheet transport path 27, receives the transfer of the toner image at the above-described secondary transfer position, and is sent to the fixing device 3 provided immediately above the secondary transfer position. Then, the recording sheet P on which the toner image is fixed by the fixing device 3 is discharged face-down to a discharge tray 1a provided at an upper portion of the printer housing 1 via a discharge roller 28. still,
In FIG. 1, reference numeral 29 denotes a registration roller that controls the timing at which the recording sheet P enters the secondary transfer position.

In forming a full-color image by the color laser beam printer configured as described above, first, the raster scanning unit 40 operates the image forming engines 10Y, 10M, 10C, and 10B in accordance with the image information of each color.
k, the photosensitive drums 11 are exposed at a predetermined timing, whereby the image forming engines 10Y, 10M, 10C, 1
On the photoconductor drum 11 of 0Bk, a toner image corresponding to the image information is formed. Each imaging engine 10Y, 10M, 10M
The toner images formed at C and 10Bk are sequentially transferred to the rotating intermediate transfer belt 20, and a multi-toner image in which the toner images of the respective colors overlap is formed on the intermediate transfer belt 20. On the other hand, the recording sheet P is sent out from the paper feed cassette 2 at a predetermined timing, and
At a timing when the toner image primarily transferred onto the secondary transfer position reaches the secondary transfer position, the toner image is inserted between the secondary transfer roller 30 and the intermediate transfer belt 20. Thus, the multiple toner image on the intermediate transfer belt 20 is secondarily transferred to the recording sheet P. Then, the fixing device 3 fixes the toner image on the recording sheet P on which the secondary transfer has been performed, whereby a full-color image is completed on the recording sheet P.

[First Embodiment] FIG. 2 shows an image forming engine 10M.
FIG. 3 is an enlarged cross-sectional view showing a first embodiment of a structure between a scanning unit and a raster scanning unit; However, in this figure, the intermediate transfer belt 20 and the primary transfer roll 15M are omitted. Although not shown in FIG. 1, the raster scanning unit 4
0 and each imaging engine 10Y, 10M, 10C, 10Bk
A middle plate 50 provided with an optical path forming plate, a shutter member, and the like, which will be described later, is provided between the raster scanning unit 40 and each of the image forming engines 10Y, 10M, 10M.
C and 10Bk are partitioned. Each of the image forming engines 10Y, 10M, 10C, and 10Bk is a photosensitive drum 1
1, a process cartridge 51 in which the drum cleaner 14 and the charging roller 12 are integrated, and a developing cartridge 52 of the developing device 13 itself. Each of the cartridges 51 and 52 is inserted into the printer from the front side. , And is positioned at a position shown in FIG. 2 by a frame (not shown). On the other hand, the upper surface of the housing of the raster scanning unit 40 has a laser beam Bm
Is formed on the photosensitive drum 11 of each of the image forming engines 10Y, 10M, 10C, and 10Bk, and the irradiation port 43 extends from the front side to the rear side (the back side of the paper in FIG. 2). It is formed in an elongated slit shape. The irradiation port 43 is covered with a seal glass 44 so that the laser beam Bm passes through the seal glass 44 and reaches the photosensitive drum 11.

The middle plate 50 is provided with a laser beam Bm entrance port 53 so as to overlap with the irradiation port 43 of the raster scanning unit 40. This entrance 53
A pair of optical path forming plates 54 and 55 is provided between the optical path forming plate 54 and the photosensitive drum 11 so as to sandwich the optical path of the laser beam Bm. The optical path forming plates 54 and 55 form an optical path chamber 56. Each of the optical path forming plates 54 and 55 is provided over the entire length of the slit-shaped entrance 53, and the optical path forming plate 54 located on the charging roller 12 side with respect to the entrance 53 is fixed to the middle plate 50. It is erected in a state. On the other hand, an optical path forming plate 55 located on the side of the developing unit 13 at the entrance 53 is integrated with the developing unit 13 to constitute a developing cartridge 52, and the developing cartridge 52 is mounted in a printer. Is positioned at the position. In addition, the entrance 53 formed in the middle plate 50
A pair of incident port forming members 57 and 58 are fixed to both sides of, respectively. When the user cleans the surface of the seal glass 44 of the raster scanning unit 40, the entrance forming members 57 and 58 function as guide rails for guiding the cleaning member along the longitudinal direction of the seal glass 44. I have. Reference numeral 59 in FIG. 2 is a seal member for sealing between the entrance port forming member 57 and the optical path forming plate 55.

The leading end of the optical path forming plate 55 integrated with the developing device 13 on the photosensitive drum 11 side is
The optical path forming plate 55 protrudes toward the charging roller 12 side from the closest position between the developing unit 13 and the developing unit 13 so that the optical path forming plate 55 receives the toner cluster even if the toner cluster unintentionally drops from the developing unit 13. This prevents the seal glass 44 of the raster scanning unit 40 from being stained. Further, an optical path chamber 56 formed by the pair of optical path forming plates 54 and 55.
The opening on the photosensitive drum 11 side is narrower than the entrance 53 formed in the middle plate 50, and is formed in a substantially triangular cross section. A substantially triangular partition wall (not shown) is provided upright on the middle plate 50 corresponding to the front side and the rear side of the optical path chamber 56. Prevents dust from entering.

Further, in the printer of the present embodiment, a swingable shutter member 64 is provided in the optical path chamber 56, and when the image forming operation is not performed, the shutter member 6 is used.
4, the seal glass 44 is shielded from the image forming engines 10Y, 10M, 10C, and 10Bk. FIG. 2 shows a state in which the shutter member 64 is open, and the laser beam Bm can cross the optical path chamber 56 and expose the photosensitive drum 11. Further, the shutter member 64 shown by a dashed line in FIG. 2 is in a state where the optical path of the laser beam Bm is closed, and the shutter member 64 connects the laser beam irradiation port 43 of the raster scanning unit 40 to the image forming engines 10Y, 10M, and 10M. It shields from 10C and 10Bk. As a result, during standby when the photoconductor drum 11 is not driven, a lump of toner or the like falls from the photoconductor drum 11 toward the seal glass 44 of the raster scanning unit 40, and the seal glass 44 is contaminated. It is possible to avoid it. The shutter member 64 is provided at a position that divides the optical path chamber 56 vertically into and out of two, and closes the distal end so as to abut the optical path forming plate 55 to thereby allow the optical path chamber 56 to be in the first position on the raster scanning unit 40 side. The light path chamber 56a and the second photosensitive drum 11 side
It is separated from the optical path chamber 56b.

In addition, since the one optical path forming plate 55 with which the swinging end of the shutter member 64 contacts is integrated with the developing cartridge 52, the inside of the optical path chamber 56 is exposed to the outside by removing the developing cartridge 52. The dust and toner attached to the shutter member 64 can be easily cleaned.

Further, in order to prevent the toner cloud from entering the optical path chamber 56 from the opening on the photosensitive drum 11 side, the inside of the optical path chamber 56 is directed toward the photosensitive drum 11 in the printer of this embodiment. It is configured such that a flowing airflow is formed. An air duct 62 is provided on the middle plate 50 below the charging roller 12, and the air duct 62 is open to the first optical path chamber 56a. In addition, all the imaging engines 10Y, 10M, 10C, 1 are located on the front side of the middle plate 50.
0Bk is provided with a common front duct (not shown), and this front duct is connected to the air duct 62. Further, an exhaust duct 63 is provided on the middle plate 50 below the developing device 13, and all the image forming engines 10 </ b> Y and 10 </ b> Y provided on the exhaust duct 63 along the rear side of the middle plate 50 are provided. 10M, 10
A common rear duct (not shown) is connected to C and 10Bk.

FIG. 3 shows the flow of air when the shutter member 64 is opened, that is, when the photosensitive drum 11 is exposed to the laser beam Bm. As shown by a broken line in this figure, the air sucked into the front duct by a fan (not shown) enters a ventilation duct 62 provided for each of the imaging engines 10Y, 10M, 10C, and 10Bk, and the ventilation duct After having spread in the axial direction of the photoconductor drum 11 in 62, it is blown into the first optical path chamber 56a. Since the shutter member 64 is not closed, the air blown into the first optical path chamber 56a flows to the photosensitive drum 11 through the second optical path chamber 56b, and further passes between the developing device 13 and the optical path forming plate 55. And flows into the exhaust duct 63 and is discharged out of the machine through the rear duct. Further, a part of the air is blown to the seal glass 44 of the raster scanning unit 40 through the entrance 53. A seal member 45 is provided in the gap between the middle plate 50 and the raster scanning unit 40 along the longitudinal direction of the seal glass 44, and between the front side and the rear side of the seal glass 44 between other devices. There is a slight gap, and the air blown to the seal glass 44 flows to the front side and the rear side as it is. Thereby, while each of the image forming engines 10Y, 10M, 10C, and 10Bk is forming a toner image, the photosensitive drum 11
Is discharged to the outside of the apparatus together with the air flow without entering the optical path chamber 56, and it is possible to effectively prevent the seal glass 44 of the raster scanning unit 40 from being stained by the toner. Has become.

FIG. 4 shows a state in which the shutter member 64 is closed, that is, each of the image forming engines 10Y, 10M, 10M.
C and 10Bk are in a standby state without forming a toner image. In this standby state, since the shutter member 64 is closed, the air blown into the first optical path chamber 56a from the air duct 62 passes through a slight gap between the shutter member 64 and the optical path forming plates 54 and 55, so that the second optical path chamber 5 is closed.
Blow out to 6b. Since such a gap is extremely small, the first
At least the amount of air blown into the light path chamber 56a will blow out vigorously into the second light path chamber 56b,
It is possible to prevent dust and toner from entering the first optical path chamber 56a from the second optical path chamber 56b only by sending a small amount of air from the air duct 62. For this reason, in the printer according to the present embodiment configured as described above, even if the amount of air blown from the blower duct 62 during standby is smaller than that during the image forming operation, a sufficient dustproof effect can be obtained, and during standby, The number of rotations of the blower fan can be intentionally reduced to reduce noise and power consumption.

The image forming engines 10Y, 10M, 10
As in the operation of C and 10Bk, a part of the airflow blown into the first optical path chamber 56a is also blown on the seal glass 44 during standby, so that the rotation speed of the blower fan is temporarily increased during this standby. If the airflow is increased, most of the increased air volume will be blown to the seal glass 44, and dust and the like attached to the seal glass 44 can be blown off by the increased airflow. That is, it is possible to clean the seal glass 44 without using any cleaning member or the like while maintaining the standby state of the printer, and if such a cleaning program is executed during standby between print jobs, the printer is bothersome. Stop and seal glass 4
The sealing glass 44 can always be maintained in a clean state without performing the cleaning of Step 4.

Further, as shown in FIG. 5, in the printer of this embodiment, each of the image forming engines 10Y, 10M, 10C, 1
A collection box 70 for waste toner is provided adjacent to the front side of the image forming engine 10Bk.
The waste toner discharged from the drum cleaner 13 and the belt cleaner 23 of Y, 10M, 10C, and 10Bk is stored in the collection box 70. This collection box 70 is provided for each of the imaging engines 10Y, 10M, 10C,
For the purpose of dropping waste toner from the 10Bk drum cleaner 13, these image forming engines 10Y, 10M, 10
C, 10Bk, so that the collection box 70 is provided with the imaging engine 10Y, 1B.
It is adjacent to the front side of a middle plate 50 that partitions the raster scanning unit 40 from 0M, 10C, and 10Bk. For this reason, when the collection box 70 is attached to the printer, the raster scanning unit 40
A front opening of a space 71 (a space surrounded by a two-dot chain line in FIG. 4, hereinafter referred to as a “cleaning space”) formed between the seal glass 44 and the laser beam entrance 53 of the middle plate 50. Are in a state of being closed by the collection box 70. On the other hand, the collection box 70
When the collection box 70 is removed at the time of replacement, etc., the front side of the cleaning space 71 is completely opened, and dust enters through the opening during the replacement work and adheres to the seal glass 44. There is a concern that it will.

However, when the collection box 70 is exchanged or the like, as in the standby state shown in FIG. 4, if the air flow is formed with the shutter member 64 closed, the entrance of the middle plate 50 can be formed. Cleaning space 7 via 53
The air blown into the cleaning space 71 flows toward the opening on the front side generated by the removal of the collection box 70, that is, toward the near side in FIG. 4, and blows out from the opening. It is possible to avoid troubles such as intrusion into the seal glass 44 due to intrusion into the seal glass 44. Specifically, ON / O of the interlock switch when the printer housing door is opened
What is necessary is just to comprise so that the said blowing fan may rotate automatically according to FF.

In the first embodiment, the air duct 62 is provided adjacent to the optical path chamber 56, and air is blown from the air duct 62 into the first optical path chamber 56a, as shown in FIG. As described above, from the front duct 73 provided with the blower fan 72, without passing through the blower duct 62,
The airflow may be directly blown into the first optical path chamber 56a. Even with this configuration, the same effect as in the above-described case using the air duct 62 can be obtained.

[Second Embodiment] Next, the middle plate 50
A second embodiment of the configuration will be described. FIG. 7 shows a second embodiment of the configuration of the middle plate 50. Also in the second embodiment, a pair of optical path forming plates 80 and 81 are provided so as to sandwich the optical path of the laser beam Bm, and the optical path forming plates 80 and 81 form the optical path chamber 56. However, the light path forming plate 81 integrated with the developing cartridge 52 has a shorter tip on the photosensitive drum 11 side than the light path forming plate 55 of the first embodiment.

Also in this embodiment, a shutter member 82 is provided in the optical path chamber 56, and when the image forming operation is not performed, the shutter member 82 is provided.
2 to move the seal glass 44 of the raster scanning unit 40 to the image forming engines 10Y, 10M, 10C,
It shields from 10Bk. FIG. 7 shows the shutter member 82.
Is open, indicating that the laser beam Bm can cross the optical path chamber 56 to expose the photosensitive drum 11. Further, as shown by a dashed line in FIG.
2 is closed, the optical path of the laser beam Bm is closed, and the shutter member 82 connects the laser beam irradiation port 43 of the raster scanning unit 40 to the image forming engine 1.
0Y, 10M, 10C, and 10Bk are shielded. As a result, as in the first embodiment, during the standby time when the photosensitive drum 11 is not driven, a lump of toner or the like is removed from the photosensitive drum 11 by the seal glass 4 of the raster scanning unit 40.
4, and the inconvenience of soiling the seal glass 44 can be avoided. However,
What is characteristic in comparison with the first embodiment is that the shutter member 8
When the shutter 2 is closed, it comes into contact with the front end of the optical path forming plate 81 on the photosensitive drum 11 side and closes an air flow discharge flow path formed between the optical path forming plate 81 and the developing device 13. .

Further, in order to prevent the toner cloud from entering the optical path chamber 56 from the opening on the photosensitive drum 11 side, an air flow is formed across the opening in the printer of this embodiment. A blow duct 83 for blowing air between the charge roller 12 and the optical path forming plate 80 is provided on the middle plate 50 below the charging roller 12, and the blow duct 83 is provided on the front side of the middle plate 50. A common front duct (not shown) is connected to all the image forming engines 10Y, 10M, 10C, and 10Bk provided along. An exhaust duct 8 is provided on the middle plate 50 below the developing device 13.
The exhaust duct 84 is connected to a rear duct (not shown) common to all the imaging engines 10Y, 10M, 10C, and 10Bk provided along the rear side of the middle plate 50. ing.

FIG. 8 shows the flow of the air flow when the shutter member 82 is opened, that is, when the photosensitive drum 11 is exposed to the laser beam Bm. As shown by the broken line in this figure, the air sucked into the front duct by a fan (not shown) enters a ventilation duct 83 provided for each of the image forming engines 10Y, 10M, 10C, and 10Bk, and the ventilation duct 83 After being spread in the axial direction of the photoconductor drum 11 in the inside 83, it is blown onto the photoconductor drum 11 along the back surface of the optical path forming plate 80. On the other hand, the air blown to the photosensitive drum 11 flows between the developing units 10Y, 10M, 10C, and 10Bk and the optical path forming plate 81, flows into the exhaust duct 84, and is discharged outside the apparatus through the rear duct. . Middle plate 50
Since the gap between the scanning unit 40 and the raster scanning unit 40 is sealed by a sealing member (not shown), the optical path chamber 56 sandwiched between the pair of optical path forming plates 80 and 81 is located around the photosensitive drum 11 where the airflow is formed. There is no negative pressure with respect to the atmosphere, and the airflow flows to the exhaust duct 84 without entering the storage chamber 56. As a result, the toner cloud generated around the photosensitive drum 11 does not enter the optical path chamber 56 and is discharged to the outside of the apparatus together with the airflow, thereby preventing the seal glass 44 of the raster scanning unit 40 from being stained by the toner. It is possible to prevent it.

FIG. 9 shows a state in which the shutter member 82 is closed, that is, each of the image forming engines 10Y, 10M, 10
C and 10Bk are in a standby state without forming a toner image. In such a standby state, the shutter member 64 blocks the exhaust flow path provided between the optical path forming plate 81 and the developing device 13, so that the air flow blown to the photosensitive drum 11 flows into the exhaust flow path. Therefore, the pressure in the optical path chamber 56 between the shutter member 82 and the photosensitive drum 11 is slightly high. There are small gaps at the front and rear ends of the photosensitive drum 11 and the optical path forming plates 80 and 81, and dust easily enters the optical path chamber 56 from outside through these gaps, as shown in FIG. If the air flow is continuously sent while the exhaust passage is closed by the shutter member 82, the air blows out of the optical path chamber 56 from these gaps. In addition, since these gaps are extremely small, the amount of air blown from the air duct 83 at least blows out of the optical path chamber 56 at a vigorous rate. Therefore, it is possible to prevent dust from entering the inside of the optical path chamber. For this reason, in the printer according to the present embodiment configured as described above, even if the amount of air blown from the air blow duct 83 during standby is smaller than that during the image forming operation, a sufficient dustproof effect can be obtained.
It is possible to intentionally reduce the rotation speed of the blower fan during standby, thereby reducing noise and power consumption.

[0040]

As described above, according to the image forming apparatus of the present invention, the air flow is formed along the predetermined flow path not only at the time of the image forming operation but also at the time of the standby, so that the raster scanning unit can be operated. It is possible to always prevent dust and toner from adhering to the seal glass covering the laser beam emission port, and by changing the air flow path during standby and that during image forming operation,
The amount of air to be blown can be reduced as compared with the time of the image forming operation, and the power consumption and noise of the blower fan can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a tandem type color laser beam printer to which the present invention is applied.

FIG. 2 is a sectional view showing a structure of a middle plate according to the first embodiment.

FIG. 3 is a cross-sectional view illustrating a flow of an air flow in a state where a shutter member according to the first embodiment is released.

FIG. 4 is a cross-sectional view illustrating a flow of an air flow in a state where a shutter member according to the first embodiment is closed.

FIG. 5 is a schematic diagram illustrating a positional relationship between a waste toner discharge box and an image forming engine.

FIG. 6 is a perspective view showing a modification of the first embodiment.

FIG. 7 is a cross-sectional view illustrating a structure of a middle plate according to a second embodiment.

FIG. 8 is a cross-sectional view illustrating a flow of an airflow in a state where a shutter member according to a second embodiment is released.

FIG. 9 is a cross-sectional view illustrating a flow of an airflow in a state where a shutter member according to a second embodiment is closed.

[Explanation of symbols]

10Y, 10M, 10C, 10Bk ... imaging engine, 1
DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 40 ... Raster scanning unit, 54,
55: optical path forming plate, 56: optical path chamber, 62: air duct,
63: exhaust duct, 64: shutter member, Bm: laser beam

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C362 DA12 DA14 DA23 EA16 EA17 2H027 JA03 JB13 JB15 JB17 JB24 JB27 JB28 JB29 JC01 JC05 JC06 JC15 2H071 BA04 BA23 BA35 DA02 DA08 DA15 5C072 AA03 CA06 DA21 HA02 JA

Claims (4)

[Claims] A raster scanning unit for emitting a laser beam modulated by image information; and an image forming engine having a photosensitive drum exposed by the laser beam and forming a toner image corresponding to the image information. An image forming apparatus that transfers a toner image formed by the image forming engine to a recording sheet to form a recorded image, wherein the image forming engine and the raster scanning unit are arranged with the optical path of the laser beam interposed therebetween. By providing a pair of optical path forming plates in parallel with the axial direction of the photoreceptor drum and forming an optical path chamber through which the laser beam passes by these optical path forming plates, the optical path chamber is appropriately advanced into the optical path by passing through the optical path chamber. A shutter member capable of bisecting the optical path chamber is provided, and further, among the optical path chambers bisected by the shutter member,
The first optical path chamber located on the side of the raster scanning unit is provided with a blower duct for feeding air into the optical path chamber, while the second optical path chamber located on the side of the image forming engine is provided with an exhaust for discharging air from the optical path chamber. An image forming apparatus comprising a duct. 2. When exposing a photosensitive drum with a laser beam, the shutter member is retracted to communicate the first optical path chamber and the second optical path chamber, and a predetermined amount of air is blown from the air duct to the first optical path chamber. On the other hand, when the photosensitive drum is not exposed, the shutter member is advanced to separate the first optical path chamber and the second optical path chamber, and a smaller amount of air is blown to the first optical path chamber than during exposure. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein air is blown to the first optical path chamber even during maintenance of the image forming engine. 4. A raster scanning unit for emitting a laser beam modulated by image information, and an image forming engine having a photosensitive drum exposed by the laser beam and forming a toner image according to the image information. An image forming apparatus that transfers a toner image formed by the image forming engine to a recording sheet to form a recorded image, wherein the image forming engine and the raster scanning unit are arranged with the optical path of the laser beam interposed therebetween. By providing a pair of optical path forming plates in parallel with the axial direction of the photoreceptor drum and forming an optical path chamber through which the laser beam passes by these optical path forming plates, the optical path chamber is appropriately advanced into the optical path by passing through the optical path chamber. A shutter member capable of bisecting the optical path chamber is provided, and further, among the optical path chambers bisected by the shutter member,
The second optical path chamber located on the side of the image forming engine is provided with a ventilation duct for feeding air into the optical path chamber and an exhaust duct for discharging air from the optical path chamber. The shutter member is retracted to connect the first optical path chamber and the second optical path chamber, and when the photosensitive drum is not exposed, the shutter member is advanced to separate the first optical path chamber and the second optical path chamber, and to release the shutter member. Wherein the opening of the exhaust duct is closed.