JPH07113793B2 - Electrophotographic copying machine - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an improvement of a ventilation cooling device for an exposure section in an electrophotographic copying machine.

BACKGROUND OF THE INVENTION

The exposure section of the electrophotographic copying apparatus is divided into unit states because a high-intensity exposure lamp is used and the exposure section itself does not like dust,
If it is used continuously for a long time, the temperature inside the machine may rise, which may cause damage such as deformation and damage to the platen glass and others. Particularly in a copying apparatus equipped with a moving original exposure type capable of copying a long original image, the exposure lamp is stopped at a certain place for a long time, and this tendency has a strong influence. Therefore, it is necessary to forcibly install a cooling device in the exposure section of such a copying machine, and in general, a ventilation cooling system using a fan, which has the simplest structure and is inexpensive, is adopted.

[Problems to be Solved by the Invention]

The ventilation cooling inside the exposure unit is often provided mainly by the two blower fans mounted on the front and back sides for the purpose of cooling the rod-shaped exposure lamp. It is also necessary to ventilate the whole body to prevent it from becoming locally high in temperature, and a ventilating cooling system having such an air blowing path is desired. Further, since the air intake hole of the blower fan is provided on the side surface of the exposure section, generally on the side plate on the front side, and configured to intake air, there is a high possibility that the toner powder floating from the image forming section, especially near the developing device, will be inhaled. , Measures for this must also be taken. However, it has been extremely difficult to satisfy these conditions without changing the basic layout of the copying machine and without increasing the manufacturing cost of the copying machine. As a result of solving the problems and improving the present invention, the present invention has a ventilation cooling function that is efficient and does not hinder the layout of each constituent unit in the copying apparatus and keeps the exposed portion clean, and also in the paper output reversing portion. The purpose of the present invention is to provide an electrophotographic copying apparatus which prevents the occurrence of dew condensation.

[Means for solving problems]

The above-mentioned objects are: an exposure unit for irradiating a photoconductor drum with a document table surface on the upper side, and an image forming unit for charging, developing, transferring, and cleaning around the photosensitive drum in the vicinity of the center, and its side. In an electrophotographic copying apparatus provided with a fixing unit and a paper discharge reversing unit on one side, the exposure unit is shielded, an intake hole is provided on the front surface of the exposure unit and a blower fan is provided behind it, and an exhaust hole and a first unit are provided on the rear surface of the exposure unit. An exhaust fan is provided, and a communication hole and a second exhaust fan are provided on the lower surface of the exposure unit.
The exhaust air exhausted by the exhaust fan is divided into two parts, a part of which is discharged from the side of the copying apparatus, a part of which is discharged to the paper output reversing unit, and the front surface of the image forming unit is shielded by an opening / closing door. The present invention is achieved by an electrophotographic copying apparatus characterized in that the opening / closing door is configured to block an air flow between the air intake hole and the image forming unit.

【Example】

FIG. 1 is a block diagram showing an embodiment of the electrophotographic copying apparatus of the present invention. In the figure, a document feeding device 80 is provided on a document table glass 81, an exposure device 30 is provided under the document feeding device 80, a photosensitive drum 11 having an image bearing member on its peripheral surface is provided below the exposure device 30, and a charger 12 is provided at the peripheral portion. , A developing device 13 having a developing roller 13a, a transfer pole 1
4, a separating electrode 15, a removing electrode 16, and a cleaner portion 17 are provided. Further, a supply device 110 for the recording paper P is provided on the right side so that the recording paper P from each paper feed cassette reaches the transfer pole through a transport path 120. Further, a conveyor 130 for conveying the recording paper P after the transfer of the toner image, a fixing unit 140, a conveyance switching gate 150 having a guide plate 154 which rotates around an operating shaft 152, a branch conveyance path 160, a backside copying conveyance path 163,
165, a recording paper intermediate stocker 170, and a backside copying conveyance path 180 are provided below. Then, a collection stand 156 is provided on the left side of the gate 150 via a delivery member. Further, the exposure device 30 forms an optical system by an exposure lamp 32, a first carriage having a mirror 34, a second carriage having mirrors 35 and 36, a projection lens 37 and a mirror 38, and a glass platen for a document table.
A photosensitive body in which the irradiation screen of the original D on 81 is charged by the charging electrode 12.
It is designed to form an image on 11. The exposure device 30 is capable of adopting an optical system moving exposure method in which the first and second traveling bases of the optical system travel parallel to a stationary document on the platen glass to scan. ,
As another form, the optical system is fixed at a specific position,
An original moving exposure system is adopted in which the original D is scanned and exposed by traveling on the original table glass 81 in synchronization with the photosensitive drum 11. That is, two modes are incorporated. Further, the exposure device 30 enables variable-magnification copying including the same size. At the front edge of the upper surface of the recording device, there is provided an operation panel (not shown) on which a display unit, a numeric keypad, a magnification selection button, a double-sided copy selection button, an exposure setting volume, a transfer paper size selection button, a copy start button, etc. are arranged. ing. When the copy start button is operated, the exposure lamp 32 irradiates the original D which is conveyed by the original feeding device 80 and is placed on the original glass 81, and the optical image of the original D passes through the exposure device 30 including the projection lens 37. And is guided to the surface of the photosensitive drum 11, which is an image carrier. The photoconductor drum 11 is provided with a Se photoconductive layer on the outer peripheral surface of a grounded metal cylinder, and rotates clockwise in conjunction with exposure scanning of the document D. The photoconductive layer of the photoconductor drum 11 is positively and uniformly charged by the charger 12 to which a high DC voltage is applied before the photoimage arrives, and when the photoconductive layer in this state receives the photoimage. , The conductivity of the part that received the light becomes high, the charged electric charge of that part escapes to the metal cylinder, and the positive electric charge remains in the dark part according to the degree of light and dark,
As a result, an electrostatic latent image corresponding to the image of the original is formed on the surface of the photoconductive layer. The developing unit 13 contains a two-component developer and is a stirring member.
When stirred by 13b, the toner becomes negatively charged,
The uniformly stirred developer adheres to the peripheral surface of the developing sleeve 13a and is carried to the developing area. When the portion of the photosensitive drum 11 on which the electrostatic latent image is formed reaches the portion of the developing sleeve 13a, the toner having a negative charge is attracted by the electrostatic force to the portion of the positive charge remaining on the surface of the photosensitive drum 11. It As a result, a toner image corresponding to the electrostatic latent image is formed on the surface of the photosensitive drum 11. On the other hand, the transfer paper P in the supply device 110 selected by the transfer paper size selection button is sent out by the paper feed roller 120a at a timing such that the front end of the transfer paper P coincides with the front end of the toner image. The toner image on the surface of the photosensitive drum 11 is transferred by the transfer pole 14 to which a DC voltage is applied to P. After that, the transfer paper P is separated from the photoconductor drum 11 by the separation pole 15 to which the AC high voltage is applied, and is sent to the fixing unit 140 by the conveyer 130 to fix the toner image, and the toner image is discharged onto the collecting table 156. Further, after the toner image is transferred onto the transfer paper P, the residual toner remaining on the peripheral surface of the photosensitive drum 11 is further discharged by the removing electrode 16 and cleaned by the cleaner unit 17, so that the next copying operation is possible. And The copy process described above is continuously performed. Single-sided copy by double-sided copy selection button (first mode)
When is selected, the documents D sequentially arranged on the document stock table 84 of the document feeding device 80 are sequentially fed from the uppermost one by the document feeding rollers 86, pass through the conveyance path 87, and are conveyed by the conveyance belt 83. Above, it is sent to a predetermined position and stopped. In this state, the optical system is provided with a function of traveling to perform scanning exposure. By repeating this process, the one-sided originals are sequentially arranged on the collection table 93 in the same order as they were on the first original stock table 84. However, the whole upside down is reversed. Further, the recording sheets P, which have been copied on one side, are turned upside down by the transport switching gate 150 and stacked in order on the collecting table 156. When the double-sided copy (second mode) is selected by the double-sided copy selection button, the front and back sides of the double-sided original are copied as the double-sided copy. That is, as described above, due to the document reversing function of the document feeding device 80, the one-side exposed document D on the document table glass 81 is reversely rotated by the reverse rotation of the conveyor belt 83.
After passing through the conveyance path 87 again, the conveyance belt 83 switched to the normal rotation again reaches a predetermined position on the platen glass, and the exposure on both sides is completed by scanning exposure while traveling the optical system. The manuscript D is placed on the collection table 93 in page order or stock table 84.
The pages can be collected by arranging them in reverse page order. In this case,
The document feed roller 86 feeds the document at the bottom. On the other hand, the recording paper on which one side has been copied passes from the branch conveyance path 160 through the conveyance path for back side copying and the intermediate stocker section, and then again on the conveyance path.
After being transferred through 120 and fixed again by the fixing device 140, the conveyance switching gate 150 determines the front side and the back side, and the sheets are collected on the collecting table 156 in page order. The high-speed printer having the one-sided copy function and the two-sided copy function described above also has a variable magnification function,
The line speed of 11 also changes depending on the variable magnification as shown below. The above conversion is performed by the control unit in the electrophotographic copying apparatus, and when the copy magnification is selected by the magnification selection button, the optical system of the exposure device 30 moves to the optical system position corresponding to the magnification and the line speed in the copying process. Is also switched. The ventilation cooling device in the electrophotographic copying machine is constructed as follows. The substrate cover on the front surface of the exposure unit 30 is provided with a plurality of parts as shown in FIGS. 1 and 3 at a portion corresponding to the position of the exposure lamp 32 when the scanning exposure method is set to the original movement exposure mode. An intake hole 20a composed of a small hole and a dust filter is opened, and the outside air is sucked into the exposure unit 30 by a blower fan attached to the inner surface thereof. Most of the sucked outside air flows while cooling the exposure lamp 32 by the suction of the first exhaust fan attached to the target position of the blower fan, and the exhaust air opened in the rear cover of the apparatus shown in FIG. It is discharged from the machine through the hole 20b. Note that neither the blower fan nor the first exhaust fan is shown. At the same time, part of the outside air sucked in passes through the inside of the exposure unit 30 and is discharged to the lower part inside the apparatus by the second exhaust fan 21. The second exhaust fan 21 is an axial fan driven by a motor 21a attached to the end of the second exhaust fan 21, and is installed in a communication hole 1a opened in the middle frame of the device. The second exhaust fan 21 divides a part of the intake outside air discharged below the exposure unit 30 into two parts, one of which is through an exhaust hole 20c opened in the left side cover of the apparatus shown in FIG. The remaining outside air discharged to the outside of the machine is sent to the transfer switching gate unit 150 of the discharge reversing unit. The outside air sent to the transfer switching gate 150 is blown onto the transfer surface of the transfer paper P that has been fixed, and at that time, the outside air whose temperature has risen appropriately by passing through the exposure unit 30 is contained in the recording paper P. It is effectively used to remove moisture and dew condensation near the transfer switching gate 150. The outside air is supplied to the intake hole 20a through a plurality of elongated holes H opened at the side edge of the left front door 41 shown in FIG. The left side door 41 is an exterior member that shields the front side of the apparatus together with the right front door 42. However, since the left side door 41 has a structure in which a slight gap is left even when the door is closed, it is possible to sufficiently suck the outside air from the elongated hole H. It is possible, and by adopting such a method, the appearance of the device is simply configured.
A plurality of the elongated holes H are also provided in the upper edge 41a of the left front door 41. When the left front door 41 and the right front door 42 are closed to shield the front of the device, the shield plates 22a, 22 provided on the inner surface of each door
b is a stepped portion 23a, 23b formed by the exposure unit 30 and the image forming unit unit.
And a shielding plate 22c provided on the left front door 41 is inserted into a gap 23c formed by the exposure unit 30 and the image forming unit unit to partition an image between the exposure unit 30 and the image forming unit unit. Air in the vicinity of the formation unit is blocked so that the air is not sucked into the exposure unit 30 through the air inlet 20a. In the image forming unit section, the developing device 13 is provided with a toner powder collecting device as shown in FIG. 4 so as to prevent the toner powder from floating during development. Opposite the upper and lower surfaces of the main body 13c of the developing device 13 and the photoconductor drum 11,
That is, a total of three rear side surfaces are airtightly covered by a cover plate 13d slightly apart from the main body 13c, and slit-shaped end surfaces on the upstream side and the downstream side facing the photoconductor drum 11 are formed. Intake holes S1 and S2 are formed, respectively. On the other hand, the space formed by the main body 13c on the rear side surface of the developing device 13 and the cover plate 13d is connected to a duct 13e extending to the rear surface of the apparatus main body, and a third exhaust fan attached to the end of the duct 13e. (Not shown) is subjected to a strong suction action during development. Therefore, even if a part of the toner powder carried by the developing sleeve 13a is scattered in the air due to friction with the photosensitive drum 11 during development, the toner powder is not immediately floated and the intake hole is immediately released.
It is sucked by S1 or S2 and is stored in a collection container provided on the back surface of the apparatus main body. Further, the cleaner portion 17 of the image forming unit portion shields the outer edge portion so that the toner removed by the cleaning blade or the like does not scatter to the outside of the cleaner portion 17. In this way, the image forming unit is kept in a state of being shielded from the outside, and at the same time, toner scattering inside is prevented.

【The invention's effect】

According to the present invention, it becomes possible to introduce a large amount of outside air into the exposure device without being contaminated with toner or paper powder, and as a result, without exposing the original document or the optical system to a high temperature,
In addition, since it can be kept clean at all times, the performance of image formation is enhanced, and an electrophotographic copying apparatus capable of obtaining high quality images is provided.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram of an electrophotographic copying apparatus of the present invention. FIG. 2 is an external perspective view of the device. FIG. 3 is a front view in which the device is opened. FIG. 4 is a sectional configuration diagram of a developing device included in the apparatus. FIG. 5 and FIG. 6 are perspective views showing the external appearance of the mechanical portion of the apparatus. 13 ... Developer, 20a ... intake hole 20b, 20c ... exhaust hole, 21 ... exhaust fan 22a, 22b, 22c ... shield plate, 23a, 23b ... step 23c ... gap, 30 ... exposure Part 41 (42) …… Left (right) side front door S1, S2 …… (slit-like) air intake hole H …… long hole, D …… original P …… recording paper

Continuation of the front page (56) References JP-A-64-59253 (JP, A) JP-A-59-149340 (JP, A) JP-A-54-136324 (JP, A) Actual development 63-150944 (JP , U) Actually open 63-146842 (JP, U) Actually open 63-115151 (JP, U) Actually open 61-34154 (JP, U) Special public Sho-57-46549 (JP, B2) Actual public 5-24924 (JP, Y2)

Claims (3)

[Claims] 1. An exposure unit for irradiating an image of a document on a photoconductor drum with a document table surface as an upper face, and an image forming unit for charging, developing, transferring, and cleaning around the photoconductor drum near the center. In an electrophotographic copying apparatus provided with a fixing section and a paper discharge reversing section on its sides, the exposure section is shielded, an intake hole is provided in front of the exposure section and a blower fan is provided behind it, and an exhaust hole and One exhaust fan is provided, a communication hole and a second exhaust fan are provided on the lower surface of the exposure section, and the exhaust air discharged by the second exhaust fan is divided into two parts and a part is discharged from the side surface of the copying apparatus. The sheet is discharged to the sheet discharge reversing section, the front surface of the image forming section is shielded by an opening / closing door, and the air flow between the intake hole and the image forming section is blocked by the opening / closing door. Characterized by Child copying machine. 2. The electrophotographic copying machine according to claim 1, wherein the opening / closing door is provided with an air flow shielding plate. 3. A third exhaust fan, which is provided with intake holes on the upstream and downstream end surfaces of a developing device facing the photoconductor drum and exhausts exhaust air from the intake holes from the rear surface of the copying machine. The electrophotographic copying apparatus according to claim 1 or 2, wherein the electrophotographic copying apparatus is provided.