JPH04274450A - Paper guiding device for image forming device - Google Patents

Abstract

PURPOSE:To offer a paper guiding device for an image forming device in which the number of paper guiding members in a paper carrying path is reduced. CONSTITUTION:A photosensitve body 24 opposingly arranged below a transfer part 39 by putting the paper carrying path 32 between them is provided so as to freely rotate. A process unit such as an electrostatic charging part 28, an exposing part 29 or a developing part 22 is arrayed around the photosensitive body 24 below the paper carrying path 32. By guiding a paper 4 by using a paper guiding surface 37 which is formed on the upper surface of a toner cartridge 36 attached to the upper part of the developing part 22, the paper guiding member need not be separately provided, structure for fixing the paper guiding member is omitted, and room is given to space where various kinds of process units are arrayed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper guide device for an image forming apparatus that forms images by electrophotography.

0002

2. Description of the Related Art Generally, in an image forming apparatus, various process units such as at least a charging section, an exposing section, and a developing section are arranged around a photoreceptor facing a transfer section with a paper conveyance path in between. A paper guide member for guiding the paper is provided on the paper transport path.

0003

[Problems to be Solved by the Invention] Paper guide members that guide paper require a certain length in order to be arranged along a paper conveyance path, but these paper guide members simply guide paper. Since the paper guiding member is provided separately for this purpose, the number of parts increases and a structure for fixing the paper guiding member is also required. Furthermore, there is a problem in that the presence of the paper guide member also affects the arrangement of various process units.

0004

[Means for Solving the Problems] The present invention provides rotatable photoreceptors that are arranged opposite to each other below a transfer section with a paper conveyance path in between, and process units such as at least a charging section, an exposure section, and a developing section. were arranged around the photoreceptor below the paper transport path, and a paper guide surface located on the paper transport path was formed on the upper surface of the toner cartridge mounted above the developing section.

[0005]

[Operation] Since the paper guide surface is formed on the top surface of the toner cartridge in the developing section, it is possible to omit a separate paper guide member or a structure for fixing this paper guide member, and it is also useful for various processes. It is also possible to have extra space for arranging units.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained based on the drawings. 1 and 2 are longitudinal sectional front views. In the figure, 1 is a paper storage section. This paper storage section 1 stores A4 size paper 4.
A flat paper feeding body 2 that is slightly larger than the above, a mounting plate 5 held movably in the width direction of the paper 4 by a protrusion 3 formed at the bottom of the paper feeding body 2, and a mounting plate 5 that is movable up and down on the paper feeding body 2. It consists of a pressing plate 6 held at Guides 7 for supporting both side edges of the paper 4 are formed on both sides of the mounting plate 5. Further, although the pressing plate 6 holds the sheets 4 in a stacked state and is biased by a spring 8 in a direction away from the mounting plate 5, the guide 7 may be provided with a stopper 9 that contacts the top layer of sheets 4. This limits excessive upward movement. Furthermore, an electrical equipment compartment 10 is provided at the bottom of the paper feed main body 2.
The electrical equipment compartment 10 is provided with an electrical equipment case 11 and a circuit board 12 connected to the electrical parts housed in the electrical equipment case 11. A plurality of legs 14 that come into contact with a desk top are fixed to a base plate 13 that closes the bottom of the electrical equipment room 10. Further, a lid 15 is provided on the upper surface of the paper feed main body 2 so as to be openable and closable.

Further, a printing unit 16 is provided above the paper storage section 1. This printing unit 16 includes a case 18 rotatably held on both sides of the paper feed body 2 by a fulcrum shaft 17, a support frame 19 and a mounting plate 20 fixedly provided on the case 18, and a fulcrum shaft. 2
It has a cover 21 rotatably held by 1a. The support frame 19 is provided with a developing section 22 that includes a developing roller 25 and a regulating roller 26 that regulates the thickness of the developer layer. In addition, this support frame 1
9 includes a paper feed roller 23, a drum-shaped photoreceptor 24,
A fixing roller 27 is rotatably held, and a motor (described later) for driving these rotating bodies including a developing roller 25 and a regulating roller 26 is fixed. Note that the outer diameter of the photoreceptor 24 is set to approximately half the outer diameter of the paper feed roller 23.

The mounting plate 20 includes a charging section 28 that applies a voltage to the photoreceptor 24 to charge the photoreceptor 24, and a charging section 28 that irradiates the charged portion of the photoreceptor 24 with a light signal corresponding to an image signal. An exposure section 29 that forms an electrostatic latent image and a photoreceptor 24
An auxiliary brush 30 that evens out the developer remaining on the outer peripheral surface of the
and an exposure lamp 30a that removes the charge from the photoreceptor 24. The exposure section 29 is formed by arranging a large number of edge light emitting elements in a line. The aforementioned photoreceptor 24, the developing roller 25 and regulation roller 26 in the developing section 22, the fixing roller 27 and the press roller 41, the charging section 28, the exposing section 29, the auxiliary brush 30, and the exposing lamp 30a. An image forming section 31 is formed by a transfer roller 39 serving as a transfer section.

A paper conveyance path 32 is formed between the case 18 and the cover 21, and the paper conveyance path 32 and the extension surface (paper feed path) of the uppermost layer of paper 4 on the press plate 6 are different from each other. , a plurality of ribs 34 connected by a reversing path 33 formed by a part of the outer circumferential surface of the paper feed roller 23, and for promoting the guiding action of the paper 4 through this reversing path 33.
is formed in the case 18. Further, a manual paper feed port 35 is formed at the end of the paper transport path 32 on the paper feed roller 23 side.

Furthermore, a paper guide surface 37 located on the paper transport path 32 is formed on the toner cartridge 36 installed in the developing section 22, and a paper guide plate 38 facing the paper guide surface 37 is formed on the paper guide surface 37. It is held by the cover 21. The transfer roller 39 is rotatably held in the cover 21 in contact with the photoreceptor 24 . The paper guide plate 38 is formed of a leaf spring, and a pinch roller 40 and a press roller 41 are mounted on both ends of the paper guide plate 38 in the case 1.
It is biased towards the 8 side and held rotatably. As a result, the pinch roller 40 is brought into pressure contact with the paper feed roller 23, and the press roller 41 is brought into pressure contact with the fixing roller 27. Further, near the tip of the press plate 6 in the paper storage section 1, a lever 4 having a friction member 42 at the tip is provided.
3 is biased clockwise by a spring 44 and the support shaft 4
It is rotatably held around 5. Thereby, the friction member 42 is brought into elastic contact with the outer peripheral surface of the paper feed roller 23. Further, a connector 46 for inputting power supply voltage, image signals, etc. is fixed to the case 18 of the printing unit 16, and a connector 47 connected to the circuit board 12 is provided in the paper storage section 1, These connectors 46 and 47 are connected by a cable 48.

Furthermore, the case 18 is provided with a stop lever 49. As shown in FIG. 3, this stop lever 49 is urged clockwise by a spring 50 and is rotatably held by a support shaft 51, and a stop shaft 52 facing the side edge of this stop lever 49 is attached to the case 18. It is erected on the side of the Further, a protrusion 53 is formed at the lower end of the stop lever 49 and comes into contact with the upper surface 2a of the paper feed main body 2. Here, FIG. 3 shows the paper feed main body 2.
2 is a side view showing the relative relationship between the upper surface 2a of the printer and the case 18 of the printing unit 16. FIG. That is, when the case 18 rotates upward about the fulcrum shaft 17, the relative position with respect to the upper surface 2a of the paper feed main body 2 changes. When the relative position of the upper surface 2a to the case 18 is L, the case 18 is located at the lower position and is in contact with the upper surface 2a of the sheet feeding main body 2. In this state, the upper surface 2a and the projection 53 contact each other. The rotational movement of the stop lever 49 is blocked, so that the upper part of the stop lever 49 projects into the manual paper feed port 35. When the relative position of the top surface 2a with respect to the case 18 is H, the case 18 is located at the upper position and is separated from the top surface 2a of the paper feed main body 2. In this state, the stop lever 49 is moved by the spring as shown by the imaginary line. It rotates clockwise due to the biasing force of 50, and its tip retreats below the manual paper feed port 35.

FIG. 4 is a front view showing the support structure of the case 18 of the printing unit 16 with respect to the paper feed main body 2. The fulcrum shaft 17 and the pin 54 are provided on the front and back surfaces of the case 18.
has been erected. Further, on the front and back sides of the paper feed main body 2, an L-shaped groove 55 for holding the fulcrum shaft 17 and a pin 5 are provided.
A notch 56 having an opening on the top surface into which the pin 54 is fitted is formed, and a hook 58 that is rotatably held on the support shaft 57 and latched to the pin 54 is provided. This hook 5
8 is biased in one direction by a spring 59,
Excessive rotational movement is prevented by the pin 60.

FIG. 5 shows the paper feed roller 2 partially in cross section.
FIG. 3 is a side view showing the support structure of No. 3; That is, a drive shaft 61 is provided that is connected to a motor via a spring clutch (not shown). The drive shaft 61 includes a hub 63 that is prevented from rotating by a pin 62, and a hub 63 that is fixed to the drive shaft 61 by a pin 62.
a hub 6 rotatably and slidably fitted in the axial direction of the hub 1;
4 and an elastic roller 65 that is rotatably fitted to one hub 63 and fixedly fitted to the other hub 64. The hub 64 is biased in one direction by a spring 66, and the hub 64 is biased in one direction by a spring 66.
A rotation transmitting portion 67 is formed on the opposing surfaces of the rotation transmitting portions 3 and 64 and is removably engaged with each other through a relationship between a protrusion and a groove. Further, a pair of rings 68 disposed on both sides of the paper feed roller 23 are fixedly fitted onto the drive shaft 61. These rings 68 are set to have an outer diameter smaller than the outer diameter of the paper feed roller 23, but a portion of the outer periphery is provided with a protrusion 6 that protrudes with a radius larger than the radius of the paper feed roller 23.
9 is integrally formed. These protrusions 69 function to press the top layer of paper 4 on the press plate 6 and separate the paper 4 from the paper feed roller 23 when the paper feed roller 23 is stopped. The spacing between the sides is set to match the width of the postcard.

In such a configuration, when printing using the paper 4 in the paper storage section 1, as shown in FIG. Maintain the state in which it is in contact with 2a. In this state, as described above, the tip of the stop lever 49 protrudes upward from the manual paper feed port 35, so that the paper feeding operation from the manual paper feed port 35 is prohibited. Then, when the paper feed roller 23 is driven clockwise, the sheets 4 stacked on the press plate 6 are separated one by one by the friction member 42 and pulled out, and are reversed toward the paper transport path 32 through the reversing path 33. . A photoreceptor 24 is attached to the paper 4 conveyed along this paper conveyance path 32.
The upper developed image is transferred by the transfer roller 39, and the transferred image is fixed by the fixing roller 27. The paper 4 with the image transferred in this way is discharged onto the top surface of the lid 15 of the paper storage section 1.

The above development is carried out by a known cleanerless reversal development method. That is, in the pre-exposure step, as shown in FIG.
As shown in (a), the photoreceptor 2 is exposed by the exposure lamp 30a.
4 are uniformly exposed, and the fatigue state of the photoreceptor 24 is made uniform.

In the charging step, as shown in FIG. 6(b),
A negative charge is uniformly applied to the photoreceptor 24 by the charging unit 28, and the photoreceptor 24 is negatively charged. At this time, the photoreceptor 24
If there is developer remaining after transfer, that developer is also negatively charged.

In the exposure process, as shown in FIG. 6(c),
The exposure section 29 partially exposes the photoreceptor 24 in accordance with the image data to attenuate the surface potential. In this process,
Even if a small amount of developer is present on the outer periphery of the photoconductor 24, the spot diameter of the exposed portion 29 is sufficiently larger than the developer particles, and the amount of light is also sufficient, so that even though the light is irradiated, there will be no residue. No exposed areas occur.

In the simultaneous development and cleaning process, FIG.
), the developer is attracted to the portion of the photoreceptor 24 where the potential is attenuated by the exposure section 29. At this time, since the developing bias potential of the developing roller 25 is an intermediate value between the potential of the portion exposed by the exposure section 29 and the potential of the unexposed section, it is attached to the unexposed section of the photoreceptor 24 and the charging section 28
The negatively charged residual developer is attracted (cleaned) by the developing roller 25.

In the transfer process, as shown in FIG. 6(e),
By applying a positive charge to the transfer roller 39, the developer on the photoreceptor 24 is transferred onto the paper 4.

In the auxiliary cleaning step, as shown in FIG. 6(f), even if a small amount of developer remains on the photoreceptor 24, the outer peripheral surface of the photoreceptor 24 is cleaned by the auxiliary brush 30.

In FIG. 3, the stop lever 49 is biased by a spring 50, and its protrusion 53 presses against the upper surface 2a of the paper feed main body 2, and the reaction force of the pressing force acts as an upward rotational force on the printing unit 16. However, when feeding paper from the paper storage section 1, as shown in FIG. Rotational movements are prevented.

Therefore, in FIG. 4, the spring 5
When the hook 58 is rotated counterclockwise against the biasing force of the spring 50 and removed from the pin 54, the stop lever 49 is rotated clockwise due to the biasing force of the spring 50, as shown by the imaginary line in FIG. Since the projection 53 presses the upper surface 2a of the paper feed main body 2, the reaction force causes the printing unit 16 to rotate upward about the fulcrum shaft 17. As a result, as shown in FIG. 2, a gap s is formed between the left upper surface of the paper feed main body 2 and the left lower surface of the case 18. In this state, the upper end of the stop lever 49 is retracted below the manual paper feed port 35, so that paper can be fed from the manual paper feed port 35.

Further, regardless of whether the paper 4 is fed from the paper storage section 1 or the manual paper feed port 35, the paper 4 is guided by a paper guide surface 37 formed on the top surface of the cartridge case 36. Therefore, the number of paper guide members can be reduced, and the structure for fixing the paper guide members can also be simplified. Note that the paper 4 is placed on the paper guide surface 37.
By forming the ribs along the conveyance direction, the contact resistance of the paper 4 with the paper guide surface 37 can be reduced.

As described above, the printing unit 16 is arranged within the range of approximately the upper surface of the paper storage section 1. Further, it becomes possible to convey the paper 4 in the paper storage section 1 and the paper inserted from the manual paper feed port 35 using only one paper feed roller 23. Furthermore, since the photoconductor 24 is disposed below the paper conveyance path 32, the mounting position of the printing unit 16 can be lowered, and the photoconductor 24 has an outer diameter equal to the outer diameter of the fixing roller 27, and the outer diameter of the paper feed roller 23 Since the outer diameter is approximately half that of the outer diameter, the distance between the paper storage section 1 and the paper transport path 32 can be reduced, and each process for charging, development, transfer, etc. of the image forming section 31 can be made small. The units can be easily arranged in a small space. Further, the paper 4 after printing can also be discharged onto the lid 15 of the paper feed main body 2. Therefore, the printing device can be extremely miniaturized.

In this embodiment, the outer diameter of the paper feed roller 23 is set to about 20 mm, and the outer diameters of the photoreceptor 24 and fixing roller 27 are set to about 10 mm. As a result, the length of the printing unit 16 in the paper feeding direction is approximately 70 mm, and the height is approximately 3 mm.
0mm, the width dimension corresponds to the width of A4 size paper 4,
It is small enough to be suitable for personal ownership. Furthermore, even if the size of the paper 4 used changes, the printing unit 16
Only the width dimension changes to some extent, and the height and length are maintained within a certain dimension.

[0026]

Effects of the Invention According to the present invention, photoreceptors are rotatably disposed opposite to each other under a transfer section with a paper conveyance path in between, and process units such as at least a charging section, an exposure section, and a development section are connected to the paper conveyance path. Since the paper guide surface located on the paper transport path is formed on the top surface of the toner cartridges arranged around the photoconductor below the path and mounted on the upper part of the developing section, the paper guide surface located on the paper transport path is formed. It is possible to guide the paper, thereby eliminating the need to provide a separate paper guide member or a structure for fixing this paper guide member. This has the advantage of allowing more space for the arrangement of process units.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing a state in which paper is fed from a paper storage section.

FIG. 2 is a longitudinal sectional front view showing a state of paper being fed from a manual paper feed slot.

FIG. 3 is a side view showing the opening/closing operation of the manual paper feed slot by the stop lever.

FIG. 4 is a front view showing the support structure of the printing unit with respect to the paper storage section.

FIG. 5 is a longitudinal side view of the paper feed roller.

FIG. 6 is an explanatory diagram showing steps for image formation.

[Explanation of symbols]

22 Developing section 24 Photoreceptor 28　　　　　Charging part 29 Exposure section 32 Paper conveyance path 36 Toner cartridge 37 Paper guide surface 39 Transfer section

Claims (1)

[Claims] 1. Photoreceptors are rotatably arranged opposite to each other below a transfer unit with a paper transport path in between, and at least process units such as a charging unit, an exposure unit, and a developing unit are located below the paper transport path. A paper guide device for an image forming apparatus, characterized in that a paper guide surface located on the paper transport path is formed on an upper surface of a toner cartridge arranged around the photoreceptor and mounted on the upper part of the developing section.