JPH04270353A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of easily making the circumferential speed of a photosensitive body coincide with that of a fixing roller. CONSTITUTION:In the image forming device, by forming a drum type photosensitive body 24 and the fixing roller 27 by making the base from the pipe stocks having the same outside diameter, the circumferential speed of the photosensitive drum 24 can be easily made to agree with that of the fixing roller 27, and furthermore, the cost of manufacture can be reduced by forming the photosensitive body 24 and the fixing roller 27 by use of the common pipe stock,. And also, it is facilitated to make the circumferential speed of the photosensitive body 24 coincide with that of the fixing roller 27 by connecting a gear fixed on the end of the photosensitive body 24 with the gear fixed on the fixing roller 27 by use of one idler gear,.

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 that forms images based on electrophotography.

0002

[Prior Art] Conventionally, an image formed on a photoreceptor is transferred to paper, and the paper with the image transferred is held between a fixing roller and a press roller to apply heat and pressure to the paper. In an image forming apparatus that fixes the image transferred to the paper, it is necessary to keep the circumferential speed of the photoreceptor and fixing roller constant in order to prevent deterioration in print quality due to variations in paper feeding pitch. .

0003

[Problems to be Solved by the Invention] Since the conventional photoreceptor has a larger outer diameter than the fixing roller, an error occurs in the reduction ratio between the photoreceptor and the fixing roller, making it difficult to equalize the circumferential speeds of both. It is. Furthermore, even if the drive source is shared, the power transmission path to the photoconductor and the power transmission path to the fixing roller are independent, which causes an error in the reduction ratio of both rotational transmission systems, resulting in a difference between the photoconductor and the fixing roller. It is difficult to keep the peripheral speed constant.

0004

[Means for Solving the Problem] The invention as claimed in claim 1 provides an image forming apparatus that forms images by electrophotography, in which a drum-shaped photoreceptor and a fixing roller are formed based on raw tubes having the same outer diameter. did.

The invention according to claim 2 is an image forming apparatus that forms images by electrophotography, in which a gear fixed to one end of a photoreceptor and a gear fixed to one end of a fixing roller are connected by one idler gear. .

[0006]

According to the first aspect of the invention, by forming the photoreceptor and the fixing roller based on raw tubes having the same outer diameter, it is easy to match the circumferential speeds of the photoreceptor and the fixing roller. Furthermore, production costs can be reduced by forming the photoreceptor and the fixing roller using a common tube.

According to the second aspect of the invention, since the gears fixed to the ends of the photoreceptor and the fixing roller are connected by only one idler gear, the circumferential speeds of the photoreceptor and the fixing roller can be matched. becomes easier. Furthermore, it becomes possible to simplify the rotation transmission structure.

[0008]

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. A developer container 22 containing developer is integrally formed on the support frame 19. Further, on this support frame 19, a paper feed roller 23, a drum-shaped photoreceptor 24, a developing roller 25, a regulating roller 26 that regulates the thickness of the developer layer, and a fixing roller 27 are rotatably mounted. A motor (described later) for driving these rotating bodies is fixed. Here, the outer diameter of the photoreceptor 24 is set to approximately half the outer diameter of the paper feed roller 23. Further, the photoreceptor 24 and the fixing roller are each formed based on a common aluminum tube having the same diameter. That is, the photoreceptor 24 has 20
The fixing roller 27 has a fluororesin layer of about 25 μm on the outer peripheral surface of the tube.

The mounting plate 20 includes a charger 28 that applies a voltage to the photoreceptor 24 to charge the photoreceptor 24, and a charger 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 developer container 22, the fixing roller 27 and the press roller 41, the charger 28, the exposure section 29, the auxiliary brush 30, and the exposure lamp 30a and the transfer roller 39 form an image forming section 31.

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.

Further, a paper guide surface 37 is formed on the toner cartridge 36 mounted in the developer container 22, and a paper guide plate 38 facing the paper guide surface 37 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 the press roller 41 are rotatably held at both ends thereof while being urged toward the case 18 side. 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 43 having a friction member 42 at the tip is biased clockwise by a spring 44 and is held rotatably about a support shaft 45. has been done. 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.

As shown in FIG. 6, gears 70 and 71 having the same diameter and the same number of teeth are fixed at one end of the shaft portion 24a of the photoreceptor 24 and one end of the shaft portion 27a of the fixing roller 27, respectively. One idler gear 72 is fitted into the support frame 19 and meshed with these gears 70 and 71, and is rotatably held by the support frame 19. In this embodiment, the photoreceptor 2
4 is connected to the motor.

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. 7(b),
A negative charge is uniformly applied to the photoreceptor 24 by the charger 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. 7(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 unit 29 and the potential of the unexposed portion, the potential of the developing roller 25 is attached to the unexposed portion of the photoreceptor 24 and the charger 28
The negatively charged residual developer is attracted (cleaned) by the developing roller 25.

In the transfer process, as shown in FIG. 7(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. 7(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 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.

As described above, by forming the photoreceptor 24 and the fixing roller 27 based on raw tubes with the same outer diameter and the same material, it is easy to match the circumferential speeds of the photoreceptor 24 and the fixing roller 27. becomes. Further, the outer diameter of the photoreceptor 24 can be made smaller to match the outer diameter of the fixing roller 27. In particular, in this embodiment, since development and cleaning of the photoreceptor 24 can be performed simultaneously, there is no need to separately arrange a cleaning device between the photoreceptor 24 and the fixing roller 27. The distance between the axes and the fixing roller 27 can be reduced. Along with this, a gear 70 fixed to the end of the photoreceptor 24 and the fixing roller 27,
71 can be connected by only one idler gear 72. This makes it possible to simplify the rotation transmission structure. Furthermore, the number of rotation transmitting members can be reduced, thereby reducing noise. Moreover, the outer diameters of the photoreceptor 24 and the fixing roller 27 are equal, and the gears 70 and 71 are also equal.
1 are connected by the idler gear 72, it is easy to match the circumferential speeds of the photoreceptor 24 and the fixing roller 27. Furthermore, production costs can be reduced by forming the photoreceptor 24 and the fixing roller 27 using a common raw tube.

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 of the outer diameter, the distance between the paper storage section 1 and the paper transport path 32 can be reduced, and the image forming section 31
It becomes possible to easily arrange each process unit for charging, development, transfer, etc. within 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.

[0029]

[Effects of the Invention] The invention as claimed in claim 1 is an image forming apparatus that forms images by electrophotography, in which a drum-shaped photoreceptor and a fixing roller are formed based on a raw tube having the same outer diameter. It is easy to match the circumferential speeds of the photoreceptor and the fixing roller, and production costs can be reduced by forming the photoreceptor and the fixing roller using a common tube. .

The invention of claim 2 is an image forming apparatus that forms images by electrophotography, in which a gear fixed to one end of a photoreceptor and a gear fixed to one end of a fixing roller are connected by one idler gear. Therefore, it is easy to match the circumferential speeds of the photoreceptor and the fixing roller, and furthermore, the number of rotation transmission members can be reduced to reduce noise and the rotation transmission structure can be simplified. have

[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 a front view showing a state in which a photoreceptor and a fixing roller are connected.

FIG. 7 is an explanatory diagram showing steps for forming an image.

[Explanation of symbols]

24 Photoreceptor 27 Fixing roller 70, 71 Gear

Claims (2)

[Claims] 1. An image forming apparatus that forms images by electrophotography, characterized in that a drum-shaped photoreceptor and a fixing roller are formed based on raw tubes having the same outer diameter. 2. An image forming apparatus that forms images by electrophotography, characterized in that a gear fixed to one end of a photoreceptor and a gear fixed to one end of a fixing roller are connected by one idler gear. Image forming device.