JPS62127758A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the formation of black streaks in a formed image, by slightly rotating a photosensitive drum in the opposite direction by reversely driving a motor after completing or before starting an image forming process and, at the time of the reverse rotation, disconnecting the reverse rotation to a developing and fixing devices by using a clutch. CONSTITUTION:By slightly rotating a photosensitive drum 53 in the opposite direction by reversely rotating a main motor 81 after completing or before starting the image forming process, the formation of black streaks which are formed when the remaining toner T sticking to the blade 79 part of a cleaner 74 is transferred to paper (p) through the photosensitive drum 53 at the time of image formation is prevented. When the main motor 81 is reversely driven, the transmission of the reverse rotation from the main motor 81 to developing devices 55 and 56 and a fixing device 71 is disconnected by claw clutches 151 and 161. Therefore, developing rollers 77 and 78, a heat roller 69, and press roller 70 are not rotated in the opposite directions. The toner T never goes out from the developing devices 55 and 56 and paper waste sticking to the paper (p) never drops at the paper of the fixing device 71.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image forming apparatus such as a copying machine.

[Conventional technology]

For example, in an image forming apparatus such as a copying line, the surface of a photoreceptor drum is generally first charged with a charger after the surface of the photoreceptor drum is neutralized with a discharge lamp. Next, the document image is exposed by an n-light device to form an electrostatic latent image, and then this electrostatic latent image is developed by a developing device to form a toner image. Next, this toner image is transferred onto paper using a transfer charger and a peeling charger, and then fixed using a fixing device.

Further, toner remaining on the surface of the photoreceptor drum after transfer is removed by a cleaner.

By the way, as this cleaner, one constructed as shown in FIGS. 14 and 15 is conventionally known.

That is, 1 is a blade that scrapes off the toner T remaining on the surface of the photoreceptor drum 2. This blade 1 is pressed against the surface of the photoreceptor drum 2 when the solenoid 3 is energized, and the solenoid 3 is demagnetized. The biasing force of the spring 4 causes the photosensitive drum 2 to be separated from the photosensitive drum 2 by a distance of 11. Further, a scraping plate 5 is provided below the blade 1, and this scraping plate 5 prevents toner particles scraped off by the blade 1 from accumulating near the blade 1 by rotating back and forth. It looks like this. Furthermore, a screw 6 is provided below the scraping plate 5, and this screw 6 is configured to send 1 to ner T dropped downward by the scraping plate 5 to the outside.

[Problem that the invention seeks to solve]

In the above conventional device, as shown in FIG.
There was a problem in that the toner T remained on the top of the toner and was transferred onto the paper during the next image formation transfer, resulting in black streaks appearing on the paper.

Therefore, it is conceivable to slightly reverse the photosensitive drum 2 before or after the start or end of the image forming process.

However, when trying to drive the photoreceptor drum 2, developing device, and fixing device with one motor, the photoreceptor drum 2
With the reverse rotation, the presenter and fixer are also reversed.

Therefore, in the developing device, there is a problem that toner comes out from the developing device, and in the fixing device, paper residue adhering to the paper falls off.

The present invention has been made based on the above circumstances, and its purpose is to prevent black streaks from forming on images even if the photosensitive drum, developing device, fixing device, etc. are driven by a single motor. It is an object of the present invention to provide an image forming apparatus which can not only prevent the appearance of the problem but also prevent the developing device and the fixing device from being reversed.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention makes it possible to rotate at least the photosensitive drum, developing device, and fixing device in the forward and reverse directions among the photosensitive drum, developing device, cleaner, fixing device, etc. that constitute the image forming process. The motor is driven by a single motor, and the motor is reversed to slightly reverse the photosensitive drum after the image forming process ends or before the start of the image forming process, and when the motor is reversed, a clutch is used to drive the photoreceptor drum to the developing device and fixing device. The invention is characterized in that it is configured to cut off the drive of the motor.

(Function) When the photosensitive drum, the developing device, and the fixing device are driven by one motor, the developing device and the fixing device are not reversed even if the photosensitive drum is reversed in order to prevent the occurrence of black streaks.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 13.

FIG. 5 shows a two-color copying apparatus as an image forming apparatus according to the present invention, and numeral 41 in this figure is the main body of the copying apparatus. A document table 42 on which a document is placed is fixed to the upper surface of the main body 41. Further, an exposure device 5,000 consisting of a lamp 43, mirrors 44 to 49, a lens 50, etc. is provided below the document table 42. The document set on the document table 42 is exposed and scanned by the exposure lamp 43 and the mirrors 44 to 46 reciprocating along the lower surface of the document table 2 during the work. In this case, the mirrors 45 and 46 move at half the speed of the mirror 44 so as to keep the optical path length constant. The reflected light from the original due to the scanning, that is, the reflected light from the original due to the light irradiation of the lamp 43 is reflected by the mirror 4.
Copying magnification setting lens 5 after being reflected by 4 to 46
0 and is further reflected by mirrors 47 to 49,
The document is guided to a photoreceptor drum 53 through a slit 52, and an image of the document is formed on the surface of the photoreceptor drum 530. The photosensitive drum 53 rotates in a predetermined direction, and the surface is first charged by the charger 54, and then the image of the document is exposed to slit light to form an electrostatic latent image. or second developing device 5
5° 56 to form a visible image by adhering toner thereto.

On the other hand, the paper p is in the upper or lower paper feed cassette 57.5.
8 are taken out one by one by paper feed rollers 59 and 60,
Conveyance roller 61.61.62°62 and guide 63.
63 to a pair of registration rollers 64, 64, aligned by the registration rollers 64, 64, and sent to an image transfer section. The paper p sent to the image transfer section comes into close contact with the surface of the photoreceptor drum 53 by the transfer charger 65, and the toner image on the photoreceptor drum 53 is transferred by the action of the transfer charger 65. The paper to which the toner acid has been transferred is electrostatically peeled off from the photoreceptor drum 53 by the action of a peeling charger 66, and is then conveyed by a conveyor belt 68 stretched between rollers 67 and 67. The transferred image is sent to a fixing device 71 consisting of a heat roller 69 and a press roller 70 that are provided opposite to each other, and the transferred image is fixed by passing therethrough. After fixing, the paper p is discharged onto a tray 73 outside the main body 41 by paper discharge rollers 72, 72. Further, the photosensitive drum 53 after the transfer is configured such that after the residual toner on the surface is removed by a cleaner 74, the residual image is erased by a static elimination lamp 75 and the photosensitive drum 53 returns to its initial state.

The exposure device 51 has a variable magnification function, and the lens 50 and mirrors 47, 48 are displaced by a motor 76 according to the amount of variable magnification.

The first and second developing devices 55 and 56 have developing rollers 77 and 78, respectively, and the first developing device 55 disposed on the upper side carries, for example, black toner T. For example, red toner T is stored in the second developing devices 56 disposed on the side. In addition, these developing devices 5
5 and 56 can be independently moved toward and away from the photoreceptor drum 53, and one of them is brought close to the photoreceptor drum 53 to develop the electrostatic latent image on the photoreceptor drum 53. ing.

When a solenoid (not shown) is energized, the cleaner 74 moves the blade 79 onto the photosensitive drum 53 due to the weight of the weight 79a.
The toner T is scraped off from the surface of the photoreceptor drum 53, and the toner T is conveyed to the outside by the screw 80.

Further, between the fixing device 71 and the exposure device 51 in the main body 41, as shown in FIGS. A main fan 83 that operates during formation and mainly cools the optical system of the exposure device 51, and a sub fan 84 that operates all the time when the main power of the device is on and mainly cools the fixing device 71 are provided. It is being

Further, as shown in FIG. 8, a driving timing pulley 85 is attached to a portion of the rotating shaft 82 of the main motor 81 that protrudes to the rear side. A timing belt 86, which is a toothed belt, is li) passed. The timing belt 86 is also wrapped around the first to fourth driven timing pulleys 87 to 90.

The first driven timing pulley 87 is arranged outside the timing belt 86, and a gear 91 is fixed to the first driven timing pulley 87. A gear 92 meshes with this gear 91, and a timing pulley 93 is fixed to this gear 92. A timing belt 95 is stretched between the timing pulley 93 and a timing pulley 94 fixed to the photoreceptor drum 53, so that the photoreceptor drum 53 is driven. A gear 96 is fixed to the timing pulley 94, and the driving force from the gear 96 is transmitted to the collection roller 80 of the cleaner 74 through gears 97 and 98 in sequence.
A collection roller 80 is driven.

The second driven timing pulley 88 is arranged inside the timing belt 86, and a gear 99 is attached to the second timing pulley 88. And the second
When the developing device 56 approaches the photosensitive drum 53, a gear 100 fixed to the developing roller 78 meshes with the gear 99, and the developing roller 78 is driven. Further, a gear 101 is meshed with the gear 99, and a first gear 101 is engaged with the gear 99.
When the developing image B55 approaches the photosensitive drum 53, the gear 102 fixed to the developing roller 77 meshes with the gear 138 fixed to the gear 101, and the developing roller 77 is driven.

The third driven timing pulley 89 is for adjusting the tension of the timing belt 86, and is arranged inside the timing belt 86.

The fourth driven timing pulley 90 is arranged outside the timing belt 86, and a gear 103 is fixed to the fourth timing pulley 90. This gear 10
Gear 104 meshes with gear 3, and gear 1 meshes with this gear 104.
05 is installed. A gear 106 fixed to one of the rollers 67 meshes with this gear 105, thereby driving a conveyor belt 68.

Furthermore, the driving force from the gear 105 is transmitted via a gear 107 to a gear 108 fixed to the heat roller 69, thereby driving the heat roller 69. Further, a gear 109 fixed to the press roller 70 meshes with the gear 108, so that the press roller 57
0 is driven together with the heat roller 69. Furthermore, the driving force from the gear 108 is transmitted sequentially through gears 110 and 111 to gears 112 and 112 fixed to the paper discharge roller 72.72, thereby driving the paper discharge roller 72.72. ing.

Note that 114 is a paper feeding motor, and this motor 114
A gear 116 is fixed to a rotating shaft 115 of the rotary shaft 115 . The driving force from the gear 116 is then applied to the gear 117, the timing pulley 118, and the timing belt 11.
The above conveyance roller 61.61.62.6 via 9...
2, and is further transmitted to paper feed rollers 59, 60 via belts 120, . . . and pulleys 121, . Further, the driving force from the gear 116 is transmitted to the registration rollers 64, 64 via the gear 122.

Further, 123 is an exposure scanning motor, and this motor 1
23 drives an exposure lamp 43 and mirrors 44 to 46 via timing pulleys 124 . . . and a timing belt 125.

The main body 41 also includes the upper unit 1 with the paper conveyance path as its boundary.
26 and a lower unit 127 (see also FIG. 13), and the paper ejection side of the upper unit 126 opens upward around the support shaft 128 on the paper feed side, as shown by the imaginary line in the figure. ing. Further, the upper unit 126 can be held in a closed state or an open state by a support structure 129.

Further, as shown in FIG. 9, the main motor 81, the first to third driven timing pulleys 87 to 89, and the timing belt 86 are located on the front side of the subframe 130, and the exposure scanning motor 123 is located on the front side of the subframe 130. 130
are installed on the rear side of each.

Furthermore, as shown in FIG. 10, a driver PC board 131 for driving the motor, a logic PC board 132 for controlling the motor, and a PC board 133 for a high voltage transformer for the charger are attached to the rear side of the subframe 130. .

As shown in FIGS. 11 and 12, this subframe 130 is attached to the rear side of the main body 41, and in this state, gears 91 and 92, gears 99 and 101,
The gear 90 and the gear 105 mesh with each other, and the rotating shaft 82 of the main motor 81 and the main fan 83 are connected.

Furthermore, as shown in FIG.
0 is attached to the rear frame 134 of the upper unit 126, and the fourth driven timing pulley 90 is attached to the rear frame 135 of the lower unit 127, respectively. Thereby, when the upper unit 126 is opened, the first to third driven timing pulleys 87 to 89 and the fourth driven timing pulley 9o are separated, and the timing belt 86 is loosened.

Furthermore, as shown in FIGS. 1 and 2, between the second driven timing pulley 88 and the gear 99, when the main motor 81 rotates normally, the second driven timing pulley 88 is connected to the gear 99. A dog clutch 151 is provided which transmits drive to the engine and cuts off the drive when reverse rotation occurs. That is, a support shaft 152 is cantilever-supported by the subframe 130, and the second driven timing pulley 88 and gear 99 are externally fitted onto the support shaft 152 so as to be rotatable and movable in the axial direction. The end surface of the second driven timing pulley 88 facing the gear 99 is provided with a
a! ! Teeth 153 are provided. On the other hand, the gear 9
One tooth 154 that meshes with the tooth 153 of the second driven timing pulley 88 in the circumferential direction is provided on the end face facing the second driven timing pulley 88 of No. 9 . Further, a spring bearing member 155 is rotatably fitted onto the support shaft 152, and a compression spring 1 is rotatably fitted onto the spring bearing member 155.
56 is externally fitted and supported, and the gear 99 is biased toward the second driven timing pulley 88 by this compression spring 156. Also, this splash receiver is the gear 9 of the member 155.
A convex portion 157 is provided on the 9 side, and this convex portion 157 is slidably fitted into a concave portion 158 provided on the opposite side to the teeth 154 of the gear 99, so that the spring receiver is connected to the member 155 and compressed. The spring 156 is configured to rotate together with the gear 99. In addition, 159 is a stopper for preventing removal. Thus, when the main motor 8 rotates in the normal direction, the main motor 8 is engaged as shown in FIG. 1, and when the main motor 8 rotates in the reverse direction, the engagement is released as shown in FIG. 2.

Furthermore, as shown in FIGS. 3 and 4, the gear 1
Also between 04 and gear 105, there is provided a dog clutch 161 that transmits drive from gear 104 to gear 105 when main motor 81 rotates in the normal direction, and cuts off the drive when the main motor 81 rotates in reverse. That is, the rear frame 135 of the lower unit 127
A support shaft 162 is supported in a cantilever manner, and this support shaft 162
The gears 104 and 105 are externally fitted so as to be rotatable and movable in the axial direction. And gear 104
On the end face facing the gear 105, there is a developing roller 577.7.
Since the rotation ratio of the heat roller 69 to the heat roller 8 is 1:1/3, three teeth 163 are provided in the circumferential direction. On the other hand, three teeth 164 that mesh with #1183 of the gear 104 in the circumferential direction are provided on the end surface of the gear 105 facing the gear 104. Further, a spring bearing member 165 is rotatably fitted onto the support shaft 162, and a compression spring 16 is fitted onto the spring bearing member 165.
6 is externally fitted and supported, and the gear 105 is biased toward the gear 104 by this compression spring 166. In addition, this spring receiver is provided with a convex portion 167 on the gear 105 side of the member 165, and this convex portion 167 is formed by the teeth 164 of the gear 105.
· is slidably fitted into a recess 168 provided on the opposite side, so that the spring receiver member 165 and the compression spring 166 rotate together with the gear 105. Note that 169 is a stopper for holding the reed. Thus, when the main motor 81 rotates in the normal direction, the main motor 81 is engaged as shown in FIG. 3, and when the main motor 81 rotates in the reverse direction, the engagement is released as shown in FIG. 4.

Furthermore, in the apparatus configured as described above, the main motor 8 is
1 is reversed, the photosensitive drum 53 is slightly reversed (approximately 5fflIR to 20ml1l).

According to the above configuration, the 8 main motors are reversed to slightly reverse the photosensitive drum 53 after the end of the image forming process or before the start of the image forming process, so that the toner remaining on the blade 79 of the cleaner 74 is It is possible to prevent T from being transferred to the paper p via the photosensitive drum 53 and appearing as black streaks during the next image formation.

Moreover, when the main motor 81 is reversed, the dog clutches 151 and 161 cut off the drive from the main motor 81 to the developing devices 55, 56 and the fixing device 71, so that the developing rollers 77 and 78 and the heat roller 6
9. Press roller 70 does not rotate reversely. Therefore, in the developing device 55, 56, the toner T does not come out from the developing device 55, 56, and in the fixing device 71, the paper p
The paper residue attached to the paper will not fall off.

Also, since dog clutches 151 and 161 were used,
Compared to one-way clutches, it has a simpler structure as it can be supported on a cantilever, resulting in lower costs and space savings.

Hey, when the main motor 81 reverses, the main fan 83
etc. are also reversed, but there is no problem in answering this.

〔Effect of the invention〕

As described above, according to the present invention, there are provided a photoreceptor drum, a developing device, a cleaner, a fixing device, etc. that constitute the image forming process, and a forward and reverse direction for driving at least the photoreceptor drum, the developing device, and the fixing device. a rotatable motor,
A clutch is provided that cuts off the drive to the developing device and the fixing device when the motor is reversed, and the motor is reversely rotated to slightly reverse the photosensitive drum after or before the start of the image forming process. Therefore, even if the photoreceptor drum, developing device, fixing device, etc. are driven by one motor, it is not only possible to prevent black streaks from appearing on the formed image, but also to drive the photosensitive drum, developing device, fixing device, etc. It has the advantage of being able to prevent the reversal of the flow.

[Brief explanation of drawings]

1 to 13 show an embodiment of the present invention. FIG. 1 is a plan view showing the engaged state of the dog clutch on the developing device side, and FIG. 2 is a plan view of the dog clutch on the developing device side. FIG. 3 is a plan view showing the dog clutch on the fuser side in an engaged state; FIG. 4 shows the dog clutch on the fuser side in a disengaged state. A plan view, FIG. 5 is a vertical sectional front view schematically showing the internal structure, FIG. 6 is a vertical sectional plan view showing the fan section, FIG. 7 is a vertical sectional front view also showing the fan section, and FIG. 8 is a driving force transmission. A diagram schematically showing the system, Figure 9 is an exploded perspective view showing the relationship between the main motor, timing belt, etc. and the subframe, and Figure 10 is the driver PC.
An exploded perspective view showing the relationship between the TFI and logic PC board and the subframe, Figure 11 is an exploded perspective view showing the relationship between the subframe and the main body, and Figure 12 is a perspective view showing the subframe attached to the main body. , Fig. 13 is a sectional view showing the subframe attached to the main body, Figs. 14 to 16 show conventional examples, Fig. 14 is a longitudinal sectional front view showing the internal structure, and Fig. 15 is a drive FIG. 16 is a perspective view showing how the motor is installed, and FIG. 16 is a perspective view showing how the drive motor and PC board are installed. 53... Photosensitive drum, 55... First phenomenon device, 5
6...Second developer, 74...Cleaner, 71.
...Fuser, 81...Main motor, 151, 161
...An engaging clutch. Patent attorney Takeshi Suzu

Claims (2)

[Claims] (1) A photoconductor drum, a developing device, a fixing device, etc. that constitute the image forming process, a motor capable of forward and reverse rotation that drives at least the photoconductor drum, developing device, and fixing device, and a reversible rotation of this motor. and a clutch that cuts off the drive to the developing device and the fixing device, and is configured to reverse the motor and slightly reverse the photosensitive drum after or before the start of the image forming process. image forming apparatus. (2) The image forming apparatus according to claim 1, wherein the clutch is a dog clutch.