JPH0980973A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing color smear and density unevenness, with high image quality by eliminating irregularities in driving caused by the drive transmission mechanism of a photoreceptor drum through the improvement of a driving mechanism. SOLUTION: In the image forming device provided with an electrophotographic drum-like image forming body to which flange members integrally molded with gears are concentrically and integrally combined to the outer periphery, the coefficient of dynamic friction between the gear and a driving gear fitted thereto is set <=0.15 and further, the gears 10T and 100T are concentrically and integrally provided on the outer peripheries of both end parts of the electrophotographic drum-like image forming body 10 and gear-driven respectively. Then, a torque limiter 101 is inserted into a driving part on either side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of charging means, image exposing means and developing means arranged in the vicinity of the peripheral surface of an image forming body, and rotates corresponding to the length of one image of the image forming body. The present invention relates to an electrophotographic image forming apparatus that forms a color image by superimposing toner images therein.

[0002]

2. Description of the Related Art As an apparatus for recording a multicolor image, a charging means, an image exposing means and a developing means of the same number as the kinds of colors required for image formation are arranged around an image forming body to form an image. While the body rotates according to the length of the image, charging, image exposure, and development are sequentially performed for each color, and the toner images are superposed to form a color toner image. A transfer type color image forming apparatus is known.

In such an apparatus, since the formation of the toner image of each color is continuously started with a slight time difference, the speed of color image formation is high, and a color image larger than the peripheral length of the image forming body is formed. It also has the feature that it can be formed.

In addition to this, as an apparatus for recording a multicolor image, a pair of charging means, image exposing means and developing means are arranged around the image forming body, and the image forming body is formed by the number of the respective separated colors. There is also known a color image forming apparatus of a type in which a toner image is rotated to form a color toner image and the toner images are collectively transferred onto a transfer material.

However, the quality of the image obtained is not always good due to the deterioration of the processing accuracy of the image forming body and the uneven rotation.

[0006]

As described above, in the image forming apparatus, particularly in the former image forming apparatus, many image forming devices such as image exposing and developing means are arranged around the drum-shaped image forming body. Since they are arranged in a high density, they can perform stable operation accurately, and in order to obtain high image quality, it is necessary to perform precision machining finish so that the drum-shaped image forming body becomes a cylinder of accurate size. It is essential that they are assembled and that their relative positions with each equipment are always kept constant.

However, even if such a basic condition is satisfied, if there is drive unevenness in the drive system, density unevenness and color misregistration occur, and the image quality of color images is significantly impaired.

An object of the present invention is to improve the image quality of a color image by using such a driving unevenness removing means.

[0009]

This object is achieved by any one of the following technical means (1) to (5).

(1) In an image forming apparatus having an electrophotographic drum-shaped image forming body in which a flange member integrally formed with a gear on the outer periphery is concentrically and integrally coupled, the material of the gear and the material of the drive gear meshing with the material. An image forming apparatus having a dynamic friction coefficient of 0.15 or less.

(2) The image forming apparatus according to item (1), wherein the drum-shaped image forming body is provided with a plurality of image exposing means.

(3) The image forming apparatus according to item (1) or (2), wherein the gear is a helical gear.

(4) An image forming apparatus characterized in that gears are concentrically and integrally provided on the outer periphery of both ends of the electrophotographic drum-shaped image forming body, and both gears are driven by gears.

(5) The image forming apparatus according to item (4), wherein a torque limiter is interposed in one of the two gear drives on both sides.

[0015]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Embodiments of each claim of the present invention, including the operation thereof, will be described with reference to FIGS.

FIG. 1 is a sectional structural view of an embodiment of a color image forming apparatus of the present invention. In this case, the image forming body is a drum-shaped image forming body, that is, a photosensitive drum 10, which is an optical glass or a transparent acrylic resin. Organic photosensitive layer (OPC) consisting of a transparent conductive layer on the outer periphery of a substrate formed of a transparent member such as
Is applied and is rotated clockwise while being grounded.

In the present invention, in the photoconductor layer of the photoconductor drum, which is the image forming point of the exposure beam for image exposure, a proper contrast is given to the light attenuation characteristics (photocarrier generation) of the photoconductor layer. It suffices that the exposure light amount has a wavelength that can be used. Therefore, the light transmittance of the transparent substrate of the photoconductor drum in the present invention does not have to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the translucent substrate, various translucent resins such as soda glass, Pyrex glass, borosilicate glass and fluorine, polyester, polycarbonate and polyethylene terephthalate used for general optical members can be used. Further, as the translucent conductive layer,
Indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, Ni,
A thin metal film that maintains translucency such as Al is used, and as a film forming method, a vacuum vapor deposition method, an active reaction vapor deposition method, various sputtering methods, various CVD methods, dip coating methods, spray coating methods, etc. are used. It As the photoconductor layer, an amorphous silicon (a-Si) alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, and various organic photosensitive layers (OP
C) can be used.

Reference numeral 11 denotes a scorotron charger, which is a charging means. The scorotron charger 11 performs a charging operation on the above-described organic photoconductor layer of the photoconductor drum 10 by a grid held at a predetermined potential and corona discharge by a discharge wire. A uniform electric potential is applied to the drum 10.

Reference numeral 12 denotes an exposure optical system which is an image exposure means, and includes LEDs, FL, E arranged in the axial direction of the photosensitive drum 10.
It is composed of light emitting elements such as L and PL and a Selfoc lens. The image signals of the respective colors read by the separate image reading device are sequentially taken out from the memory and input as electric signals to the respective exposure optical systems 12.
The emission wavelengths of the light emitting devices used in this example have the same wavelength and are in the range of 500 to 900 nm.

Each of the exposure optical systems 12 is mounted on a common columnar support member 20, and each exposure optical system 1
2 (Y), 12 (M), 12 (C) and 12 (K) are arranged at equal intervals and are housed inside the base of the photosensitive drum 10. The exposure optical system 12 is an LC in addition to the above light emitting element.
It may be composed of a combination of optical shutter members such as D, LISA, PLZT and an imaging lens such as a SELFOC lens.

Reference numerals 13Y, 13M, 13C and 13K denote developing units which are developing means for containing yellow (Y), magenta (M), cyan (C) and black (K) developers, respectively.
The developing sleeves 130 rotate in the same direction while maintaining a predetermined gap with respect to the peripheral surface of the photoconductor drum 10.

Each of the developing devices 13 is the charging device 1 described above.
The electrostatic latent image formed on the photosensitive drum 10 by the charging by 1 and the image exposure by the exposure optical system 12 is reversely developed in a non-contact state by applying a developing bias voltage.

Next, the process of the color image forming apparatus equipped with the image forming body of the present invention will be described.

The image of the original is read by an image reading device separate from the present device, and the image read by the image pickup device or the image edited by the computer is once used as an image signal for each color of Y, M, C and K. Stored and stored in memory.

When the image recording is started, the photoconductor drive motor is activated to rotate the photoconductor drum 10 in the clockwise direction through the drive system, and at the same time, a potential is applied to the photoconductor drum 10 by the charging action of the charger 11 (Y). Is started.

After a potential is applied to the photoconductor drum 10, image exposure is started by the electric signal corresponding to the first color signal, that is, the image signal of yellow (Y) in the exposure optical system 12 (Y), and the drum is started. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by the rotational scanning of.

The latent image is reversely developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second image of the exposure optical system 12 (M).
Image signal is performed by an electric signal corresponding to the color signal of (1), that is, a magenta (M) image signal, and non-contact reversal development by the developing device 13 (M) causes magenta () on the yellow (Y) toner image. The toner images of M) are sequentially superposed and formed.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing device 13 (C) further form a cyan (C) toner image corresponding to the third color signal.
Further, finally, a black (K) toner image corresponding to the fourth color signal is sequentially formed by the charging device 11 (K), the exposure optical system 12 (K), and the developing device 13 (K) to form a photoconductor. A color toner image is formed on the peripheral surface of the drum 10 within one rotation, and sometimes over one rotation.

The color toner image thus formed on the peripheral surface of the photosensitive drum 10 is a transfer material which is conveyed from the paper feed cassette 15 in the transfer device 14A and is fed in synchronization with the driving of the timing roller 16. It is transferred onto the transfer paper.

The transfer paper on which the toner image has been transferred is separated from the peripheral surface of the drum by removing the charge in the static eliminator 14B, and the toner is fused and fixed in the fixing device 17, and then the discharge roller 18 is fixed. Via the tray 20 on the top of the device
Is discharged above zero.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
The cleaning device 19 removes and cleans residual toner to continue forming the toner image of the original image, or temporarily stops and waits for formation of a new toner image of the original image.

The photoconductor drum 10 is composed of the chargers 1
1, a developing device 13, a cleaning device 19, a toner storage container 40 that supplies toner to each of the developing devices 13, and a waste toner container 50 that stores the toner collected by the cleaning device 19 are stored in the process cartridge 30. Thus, it is possible to integrally pull out and move from the apparatus main body, for example, in the horizontal direction, and further to take it out of the apparatus main body. This take-out structure will be described later.

FIG. 2 is a sectional view taken along the line AA in FIG. 1, in which the photosensitive drum 10 is concentrically fitted and fixed to the flange member 10A at the front end portion, and the flange member 10A is provided with a bearing B3. An intermediate portion near the end of the fixed shaft member 21 of the support member 20 of the exposure optical system 12 which is the image exposure means is concentrically supported, and the end of the fixed shaft member 21 is fixed to the wall surface of the process cartridge 30. The holes are concentrically fitted and directly fixed and supported. The rear end flange member 10B concentrically supports an intermediate portion near the opposite end of the fixed shaft member 21 via a bearing B4. At the same time, the opposite end of the fixed shaft member 21 is fixed and supported in a concentric fitting hole at the center of the disk member 30A that is attachable to and detachable from the process cartridge 30.

A gear 10T is integrally provided on either one of the flange members 10A and 10B, here 10B.

This FIG. 2 can be said to be a partial cross-sectional view showing the structure around the photosensitive drum, in which both ends of the photosensitive drum 10 are flange members 10A and 10B and concentric with no center runout and uniform and correct rotation. In addition to being able to do so, the assembly and adjustment can be performed in the simplest possible state.

That is, since the photosensitive drum 10 is made of plastic by the centrifugal polymerization method except that made of glass, the dimensional accuracy of the outer diameter is high. Therefore, by fitting the flange members 10A and 10B on the basis of the outer diameter of the photosensitive drum 10, it is possible to relatively easily perform highly accurate coupling in which the runout is less likely to occur.

At the same time, as shown in FIG.
Flange members 10A, 10 as also shown in the perspective view of FIG.
B is lightly press-fitted to fit the flange members 10A, 10B.
From the inside of the flange member 1 to a position corresponding to the contact surface of the contact roller 131 of the inner diameter portion of the photosensitive drum 10.
The flange members 10A, 10A are arranged so that the pressing member 10K integrally provided on the 0A, 10B abuts elastically.
It is molded integrally with B. As described above, the gear member 10T is integrally and concentrically provided on the flange member 10B.
The contact roller 131 is a roller provided concentrically at both ends of the sleeve roller 130, and regulates the interval of the sleeve roller 130 at the developing position with respect to the photosensitive drum 10. The abutting force of the abutting roller is considerably large, which may cause deformation and distortion of the thin photosensitive drum.
By B, the photosensitive drum is reinforced so that the correct shape is always maintained stably.

As a result, one of the basic conditions for maintaining high image quality in color image formation is established.

However, nevertheless, the photosensitive drum and the gear integrated therewith are concentric, and there is no eccentricity, and some eccentricity remains. When the drive system operates in such a state and the drive transmission is performed by the gear train, the rotation speed of the photosensitive drum fluctuates.
That is, the drive transmission to the gear is performed by the geometrical movement of the contact part through the contact between the teeth of the gear, but when the frictional force of the contact part is large, the load becomes large and the motor of the drive source becomes overloaded. Driving unevenness appears. There is a method of increasing the power of the motor as one means for removing the driving unevenness, but this is not a good idea at all because the space, weight and cost increase.

Therefore, in the embodiment of claim 1 of the present invention, an attempt was made to reduce the coefficient of dynamic friction between the teeth of the contacting gears. Therefore, as a means for reducing the coefficient of dynamic friction, mutual materials of the gears that mesh with each other were examined and tested, and the results shown in Table 1 below were obtained.

[0043]

[Table 1]

The material of the flange member concentrically connected to the photosensitive drum as the image forming body is polycarbonate (P
C) and acrylic resin (PMMA) are used, and the gear is also integrally molded. Therefore, if the materials of the driving gears meshing with this are the same polycarbonate (PC) or acrylic resin (PMMA) or the combination of polycarbonate (PC) and polyacetal (POM), the dynamic friction coefficient becomes large. Vibration and noise during transmission of the drive become large, causing color misregistration and uneven density of the image.

However, the respective materials of the combination of the gear of the flange member and the drive gear that meshes therewith are made of a combination of acrylic resin (PMMA) and polyacetal (POM), a combination of acrylic resin (PMMA) and nylon (PA), or polycarbonate. It has been found that when (PC) and nylon (PA) are combined, the dynamic friction coefficient becomes much smaller, vibration and noise during drive transmission are reduced, and image color deviation and density unevenness are almost eliminated. It was also found that if the coefficient of kinetic friction is 0.15 or less, the color misregistration and density unevenness can be suppressed to a level without problems.

Although the dynamic friction coefficient is small between POMs and PAs, the combination of the same materials causes another problem such as baking and deterioration in durability, but the object of the present invention can be achieved for the time being.

In the embodiment of the present invention, each exposure optical system is arranged at a high density on the circumference of the photoconductor drum, and the overlap of the image exposures is performed at a certain regular rotation of the photoconductor. Since it is influenced by not a regular driving unevenness which is repeated but a completely irregular driving unevenness within one rotation, the means for reducing the dynamic friction coefficient used in the present invention is a color image forming method having such an image forming method. Particularly effective for the device.

Further, when the gear is a helical gear, the meshing ratio increases as compared with the spur gear, so that much smoother drive transmission can be obtained. Further, it is more effective in reducing vibration and noise, and high image quality can be obtained.

Next, an embodiment of claim 4 will be described.

As shown in the front view of FIG. 5, gears 10T and 100T are concentrically mounted on both sides of the photosensitive drum 10, and both gears 10T and 100T are synchronized by drive gears 10Z and 100Z. It is designed to be driven. As a result, even if the photoconductor drum is a thin-walled cylindrical body, smooth rotation can be obtained without being subjected to twisting stress, and uneven driving is less likely to occur.

In the fifth embodiment, as shown in the front view of FIG. 6, the gears 10T and 100T on both sides are driven through separate drive transmission devices, and a torque limiter 101 is connected in the middle of one drive transmission device. It was provided by.

That is, the gear 10Z is meshed with the gear 10Z directly connected to the stepping motor 10M, and the gear 100
A gear 100Z meshes with T, and the shaft of the gear 100Z has a gear 10 directly connected to an AC or DC motor 104.
A gear 102 meshing with the gear 3 is concentrically arranged, and the gear 10
The torque limiter 101 is concentrically connected between 0Z and the gear 102, and is connected thereto.

In this way, the drive transmission by the stepping motor 10M on one side is transmitted to the photosensitive drum by the independent auxiliary drive transmission by the AC or DC motor on the other side, so that smooth rotation with almost no speed unevenness is transmitted to the photosensitive drum. To be

As a result, a high-quality image free from color misregistration and density unevenness can be stably obtained.

Now, as shown in FIGS. 7 and 8, the photosensitive drum 10 as an image forming body is attached and housed in the cartridge 30 of the process unit. The cartridge is different from the main body of the color image forming apparatus. It can be moved diagonally upward and horizontally. That is, the photosensitive drum 1
0 is movable in the direction perpendicular to the rotation axis. The structure of this movement will be described in detail.

The process cartridge 30 is moved horizontally obliquely upward by opening the side cover 80 forming the side member of the image forming apparatus main body, and then pulled out from the position, so that the process cartridge 30 is horizontally oriented toward the outside of the apparatus main body. Be moved to.

FIG. 7A shows a supporting structure of the process cartridge 30, and FIG. 7B shows a cross section BB which is a main part thereof. The long holes 60A of the
A pair of lift plates 61, which are connected to A by engaging a pin P1 from the inside, are slidably supported from diagonally above to diagonally below.

Inside each of the elevating plates 61, a guide member 70 capable of expanding and contracting in two stages by three rails called accuride rails is attached, and further, a moving plate 71 is attached to each inner rail. Is fixed.

Each of the moving plates 71 is provided with a pair of U-shaped notches at opposite positions, and each of the notches has a pin P.
The process cartridge 3 described above by engaging 2
Supports 0.

On the other hand, each of the elevating plates 61 is provided with a vertically elongated slot 61A, and the pin P3 on the arm which rotates about the rotation axis H as a fulcrum is loosely engaged with the side cover 80.

When the side cover 80 is rotated clockwise to be opened and placed at a horizontal stop position, the lift plate 61 is slanted upward by the movement of the pin P3 so that the pin P1 slides in the elongated hole 60A. Then, it moves diagonally downward and then stops. In this process, the process cartridge 30
Is the timing roller 1 from the image forming position (I).
6, the transfer device 14A, the static eliminator 14B, and the like are moved around to set the drawing position (II).

When the process cartridge 30 is pulled out from the pull-out position (II), it is moved to the outside of the image forming apparatus main body while maintaining the horizontal state as shown in FIG. 6 due to the extension of the guide member 70. In the process, the locking member 30B at the lower end of the cartridge 30 is attached to the side cover 80.
The recesses 81A and 81B of the elastic member 81 provided on the inner surface of the cartridge 30 are sequentially engaged so that the cartridge 30 can be restricted and stopped at a specified position.

That is, at the position where the locking member 30B engages with the recess 81A of the elastic member 81, the image transfer area of the main body of the image forming apparatus is opened and the upper cover 90 can be opened to process jammed paper. At the position where it engages with 81B, the above-mentioned exposure optical system 12 can be exchanged from the back surface of the cartridge 30, and it is further pulled out to bring the cartridge 30 into contact with the rising portion 80A of the side cover 80 at the stop position (II
In I), the waste toner container 50 can be taken out. Further, at the stop position (III), the engagement between the pin P2 and the moving plate 71 can be released to separate the cartridge 30 upward and remove it.

When the process cartridge 30 constrained at each of the specified positions and placed in the stopped state is moved so as to be pushed into the main body of the image forming apparatus, the process cartridge 30 is retracted to the above-mentioned pull-out position due to the contraction of the guide member 70. Will be restored. During this time, since the pin P1 is locked to the end of the elongated hole 60A of the substrate 60 by its own weight, the elevating plate 61 is kept stationary. Next, when the side cover 80 is rotated counterclockwise to be closed and brought into a vertical state, the pin P
3 is moved, the pin P1 of the lift plate 61 is moved to the above-mentioned long hole 60.
By sliding in A, it moves from diagonally above to diagonally below and stops at the initial position.
0 is returned to the image forming position (I) again without contacting the transfer device 14A or the like.

Therefore, inspection of the process cartridge 30
Each maintenance work such as replacement, jam paper processing, toner supply, waste toner collection, and the like can be easily performed by operating from one side surface of the apparatus main body.

In this embodiment, the exposure optical system 1
Although the apparatus of the type in which 2 is placed inside the photosensitive drum 10 has been described, the present invention is not limited to the exposure optical system 12 as shown in FIG.
Is also supported by a ring-shaped support member 20A concentrically provided on the outer periphery of the photoconductor drum 10 to perform image exposure from the outside to the photoconductor on the drum peripheral surface. As in the case of this embodiment, the cartridge is configured as a cartridge, and is realized by opening the side surface member of the apparatus and pulling it horizontally from the image forming position to the specified position.

[0067]

According to the present invention, the drive unevenness due to the drive transmission mechanism of the photoconductor drum is eliminated by improving the drive mechanism, and the color shift and the density unevenness can be eliminated. Therefore, an image forming apparatus capable of stably obtaining high image quality has been established.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an embodiment of a color image forming apparatus of the present invention.

FIG. 2 is a sectional view showing a built-in structure of a photosensitive drum and an exposure optical system.

FIG. 3 is a perspective view of a flange member.

FIG. 4 is a perspective view of a flange member.

FIG. 5 is a front view showing an embodiment in which both sides of a photosensitive drum are driven.

FIG. 6 is a front view showing another embodiment of driving both sides of the photosensitive drum.

FIG. 7 is an explanatory diagram showing a relationship between an image forming position and a drawing position of the process cartridge.

FIG. 8 is an explanatory view showing a structure for pulling out a process cartridge and restrictions on a specific position.

FIG. 9 is a sectional configuration diagram of another embodiment of the color image forming apparatus of the present invention.

[Explanation of symbols]

1 Color Image Forming Apparatus Main Body 10 Photosensitive Drums 10A, 10B Flange Member 10K Pressing Member 10M Stepping Motor 10T, 10Z, 100T, 100Z, 102, 103
Gear 11 Charging device 12 Exposure optical system as image exposing means 13 Developing device 20 Supporting member 21 Fixing member 21A Groove 30 Process cartridge 30A Disc member 30E stand 101 Torque limiter 104 Motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Hama ▼ Shuta Ta, 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Toshihide Miura 5-14-14 Midori-cho, Koganei-shi, Tokyo

Claims (5)

[Claims] 1. An image forming apparatus having an electrophotographic drum-shaped image forming body in which a flange member integrally formed with a gear on the outer periphery is concentrically integrally connected, and a material of the gear and a material of a drive gear meshing with the material. Dynamic friction coefficient between 0.1
An image forming apparatus characterized in that the number is 5 or less. 2. The image forming apparatus according to claim 1, wherein the drum-shaped image forming body is provided with a plurality of image exposing means. 3. The image forming apparatus according to claim 1, wherein the gear is a helical gear. 4. An image forming apparatus, wherein gears are concentrically and integrally provided on the outer periphery of both ends of an electrophotographic drum image forming body, and both gears are driven by gears. 5. The image forming apparatus according to claim 4, wherein a torque limiter is interposed in one of the both gear drives.