JPH02150883A - Color image forming device - Google Patents

Abstract

PURPOSE:To securely hold a photosensitive body and obtain an image of high picture quality and to facilitate maintenance such as the replacement of a photosensitive body by tapering either or both of the engagement parts of the end parts of a photosensitive drum and flanges which hold the photosensitive drum. CONSTITUTION:This device has the flanges 122 and 123 which hold the photosensitive drum 121 by engaging the end parts of the photosensitive drum 121 and a photosensitive drum guide 138 which guides the photosensitive drum 121 when the photosensitive drum 121 is inserted or extracted and normally form a gap with the photosensitive drum. In this case, either or both of the engagement parts of the end parts of the photosensitive drum 121 and the flanges 122 and 123 are tapered. Consequently, the deviation between the photosensitive drum and the flanges which hold it is eliminated to obtain the image of high picture quality without any rotational variation of the photosensitive drum, which can easily be detached during the maintenance such as the replacement of the photosensitive drum, thereby improving the maintainability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to image forming apparatuses such as color copying machines and color printers that apply electrophotography.

2. Description of the Related Art Conventionally, copying machines, printers, etc. that utilize electrophotography require accurate rotation of a photoreceptor drum that rotates while holding an electrostatic image, and fluctuations in this rotation may cause jitter or unevenness in the image. In addition, especially in devices that create color images, images are usually formed for each color and then superimposed to create a single color image, so the images for each color must be aligned accurately both partially and as a whole. There is a need. Therefore, a reliable structure for holding the photoreceptor drum is important. Usually, in copying machines, printers, etc., the photosensitive drum is held by a method in which flanges are integrally fixed to both ends of the photosensitive drum and the drum is rotatably supported around the flanges. Hereinafter, special public service 1975-20
The structure of such a conventional example used in the color copying machine shown in the No. 577 publication will be explained with reference to FIG. In FIG. 4, reference numeral 150 denotes a photoreceptor unit, and a front flange 152 and a rear flange 153 are integrally fixed to both ends of a photoreceptor drum 151. Bearings 154 and 155 are attached to the front flange 152 and the rear flange 153, respectively, and these photoreceptor units are rotatably supported around a shaft 156. A gear 157 is also integrally fixed to the rear flange 153, through which the photosensitive drum 151 is rotationally driven by a drive gear 158. In this device, the photosensitive drum 151 and the front flange 152 are used to insert and remove the photosensitive drum during replacement or maintenance.
, rear flange 153, bearing 154,155, gear 15
7 etc. are integrally inserted and removed from the shaft 156.

Problems to be Solved by the Invention In the configuration of this conventional example, the photoreceptor drum and each flange are engaged with each other at the cylindrical portion 159 and 160, but it is necessary to be able to insert and remove the photoreceptor drum for replacement. A gap is created. In particular, as the diameter of the photoreceptor drum becomes larger, the size variation in each diameter becomes larger, and the gap also becomes larger. The photosensitive drum is gear 157
, the photoreceptor drum is driven through the rear flange 160, and the photoreceptor drum receives external force through its outer circumferential surface from a developing device or other push means. Therefore, misalignment between the drive system and the photosensitive drum is likely to occur due to the gap between the photosensitive drum and the flange. If this deviation occurs, the speed of the photoreceptor drum will fluctuate even if the drive diameter is driven at a constant speed, and especially in color copying machines, the mutual positions of the images of each color to be overlapped will easily shift. . On the other hand, in order to eliminate this misalignment, there is a method of completely integrating the photoreceptor drum and flange with adhesive or other means, but in this case, when replacing the photoreceptor drum, the flange must also be discarded, which is wasteful. .

In view of these points, the present invention is capable of reliably holding the photoreceptor, thereby producing high-quality images without jitter or unevenness, and especially in the case of color, with no color shift. An object of the present invention is to provide an excellent color image forming apparatus that is easy to maintain.

Means for Solving the Problems The present invention provides a photoreceptor drum that rotates while holding an electrostatic image;
a plurality of developing means that sequentially form toner images of a plurality of colors on the photoreceptor drum; a flange that engages an end of the photoreceptor drum to hold the photoreceptor drum; and a flange that holds the photoreceptor drum. a photoreceptor guide that guides the photoreceptor drum when it is inserted or removed, and usually has a gap between it and the photoreceptor drum; This is a color image forming device with a color image forming system.

Effects of the Invention With the above-described configuration, the present invention eliminates the gap misalignment between the photoreceptor drum and the flange that holds it, provides high-quality images without fluctuations in the rotation of the photoreceptor drum, and eliminates maintenance such as replacement of the photoreceptor drum. The object of the present invention is to provide a color image device that is easy to maintain and allows the photoreceptor drum to be easily removed at times.

Embodiment FIG. 1 is a front view showing the overall configuration of a digital color copying machine to which the present invention is applied. Its configuration and operation will be explained below.

1 is a reading section of a digital color copying machine, which mainly includes an original table 2, an original illumination lamp 3, a lens 4, a color line sensor 5, a drive system 6 for moving these in the sub-scanning direction for scanning, and an image processing circuit ( (not shown in this figure).

IO is a writing section of the digital color copying machine.

Reference numeral 11 denotes a Se-based photoreceptor which has increased sensitivity to laser light having a wavelength of 780 to 810 nm, and is rotatably supported in the direction indicated by the arrow. 2 is a first charger for charging the surface of the photoreceptor 11 to a predetermined positive potential, and 26 is a laser beam.

Reference numeral 20 denotes a laser optical section, and the laser beam 26 is emitted from a laser oscillation block 21 and is configured to scan the photoreceptor 11 via a polygon scanner 22, a lens system 23, and mirrors 24 and 25. A part of the scanning light of the laser beam light 26 is reflected by the mirror 27, and the scanning light of the laser beam light 26 is reflected by the starting edge detection sensor 2.
8 is irradiated. There is a developing section 30 on the right side of the photoreceptor 11, and along the periphery of the photoreceptor 11, from the top, there are a Y developer 31 for developing yellow color, an M developer 32 for developing magenta color, and a C developer for developing cyan color. A developing device 33 (hereinafter collectively referred to as a color developing device) and a developing device 34 for developing black color are arranged. The Y developing device 3L, the M developing device 32, and the C developing device 33 are non-contact developing devices that use non-magnetic one-component toner, and are capable of developing while flying the toner onto the photoreceptor 11 without contacting it. be. The K developing device 34 is 2
Developing using a component developer while bringing the developer into contact f
It is an i-image device. Each developing device can take two positions, one close to the photoconductor 11 and the other a distance away, and by rotating the eccentric cam 35 to 3, the Y
Developer 31, Mft! The rear parts of the imager 32 and C developer 33 are pushed and moved horizontally to approach the photoconductor, and the K developer 34
M developing unit 3 is rotated counterclockwise around the shaft 3 and brought close to the photoreceptor and ready for development.
The case where only No. 2 is in a developable state is shown.

40 is an eccentric cam 35, 36, 37, 38 and a developing device 31
．． This is the motor that drives 32, 33, and 34.

Reference numeral 50 denotes a paper feed unit, which includes cassettes 51, 52 and manual paper feed unit 5.
The paper 56 can be fed one by one from each of the cassettes 51 and 56 in this figure. Paper 56 is fed to the lower surface of photoreceptor 11 via registration rollers 54 .

Reference numeral 60 denotes a transfer conveyance section, in which a semiconductive belt 63 suspended between rollers 61 and 62 can be in two states: a state in which a portion thereof is lightly pressed against the photoreceptor 11, and a state in which it is separated from the photoreceptor 11. It is also possible to move in the direction of arrow B at the same speed as the outer peripheral surface of the photoreceptor 11. In this figure, photoreceptor 1
1 shows the state of pressure contact. On the other hand, 64 is the second
A charger connects the belt 63 and the photoreceptor 11 via the belt 63.
A negative high potential is applied to the back surface of the paper 56 being fed during this period. Reference numeral 65 denotes a cleaning blade for cleaning toner remaining on the belt, and a collection box 66 is disposed below the cleaning blade.

69 is a third charger that sprinkles negative corona when the paper 56 is separated from the belt 63.

Reference numeral 70 is a fixing and paper ejecting section, in which a heat roller 72 heated by a fixing lamp 71 and a rubber roller 73 are rotatable while being in pressure contact with each other, and a paper ejection roller 74.7 is provided at the rear thereof.
5 and a paper discharge tray 76 are provided.

Reference numeral 80 denotes a cleaner which can take two states, a state in which the fur brush 81 is in light contact with the photoreceptor 11, and a state in which it is separated from the photoreceptor 11, and is rotatable in the direction indicated by the arrow. This figure shows a state in which it is in contact with the photoreceptor 11.

Furthermore, a collection roller 82 is rotatably disposed in contact with the fur brush 81, and a negative voltage is applied to the photoreceptor 11 to each of the fur brush 81 and the collection roller 82. A recovery screw 83 is installed at the bottom of the recovery roller 82.
A vibrator 84 is connected to the front end of 3 and connected to a collection box 85 through this. A fourth charger 84 for positively charging the toner on the photoreceptor 11 is provided at a position opposite to the photoreceptor at the bottom of the cleaner 80;
A static elimination lamp 87 for eliminating static electricity from the battery 1 is disposed.

Reference numerals 91 and 92 are cooling fans for sucking air from the lower and upper parts of the writing section 10 and discharging it outside the apparatus.

The above is an overview of the overall configuration of a digital color copying machine to which the present invention is applied.Next, its operation will be explained with a focus on the writing section.

When the original is placed on the document table 2 and the copying operation begins,
A document is read by a reading section 1, and an image to be recorded by a writing section 10 is determined accordingly.

In the writing section, signals to be recorded are manually input in the order of black, yellow, magenta, and cyan. First, a black signal is manually applied to the laser oscillation block 21, and the photoreceptor 11 is irradiated with a laser beam 26 modulated according to the black signal.

The photoreceptor 11 is rotated in the direction of the arrow while the first charger 12
After being uniformly charged to +850■, the area irradiated with the laser beam 26 according to the signal becomes +50V.
Static electricity is removed to a certain degree. Laser beam 11 on photoreceptor II
The main scanning of the light 26 is performed by the polygon scanner 22, and the sub-scanning is performed by rotating the photoreceptor 11 in the direction of the arrow, forming a latent image on the photoreceptor. When a latent image is first written on the photoreceptor, the developing unit 30 is set to a black developing state, and only the K developer 34 approaches the photoreceptor 11 by the operation of the eccentric cam 38, while the other developers move away. in a state. Therefore, the latent image corresponding to the black signal formed by the laser beam 26 is developed with black toner by the developing device 34 and passes through other developing devices without being affected. At this time, the timing of contact and separation of the developing device 34 is controlled so that the developing device 34 approaches the photoreceptor 11 before the laser beam 26 starts exposing it, and separates it after development. The image developed with black toner reaches the transfer conveyance section 60 as the photoreceptor 11 rotates, but at this time, in the transfer conveyance section 60, the rollers 67 and 68 are at a position slightly rotated clockwise around the axis of the roller 62. , the belt 63 is in a state separated from the surface of the photoreceptor 11, and the image passes through without being disturbed. Furthermore, the fur brush 81 is in a state separated from the photoreceptor 11 at a position slightly rotated counterclockwise around the axis of the collection screw 83, and here too, the black toner image passes through without being disturbed and returns to the first charger. Pass under 12. Photoreceptor 11
The portion where the black toner image was formed is again charged to the first charger 12.
The toner is recharged from above, and the area without toner becomes +
850■, the part where the toner is also apparently charged to +850V.

The leading edge of the black toner image is recharged and exposed to the laser beam 2 again.
When reaching the irradiation position 6, the laser beam light 26 is modulated according to the yellow signal and is exposed from above the black toner image on the photoreceptor 11. Since the leading edges of the images are aligned and the scanning speed is constant, the black toner image and the latent image of the yellow signal are formed in positional alignment. Since only the Y developing device 31 of the developing section 30 is close to the photoconductor 11 and the other developing devices are separated, the latent image formed by the yellow signal is developed only with yellow toner and is not deposited on the photoconductor. A yellow toner image is formed in addition to a black toner image. At this time, the timing of approach and separation of the Y developing device 31 is controlled so that the Y developing device 31 moves close to the photoreceptor 11 before the exposure starts with the laser beam 26, and moves away after development. Further, since the yellow development is performed in a non-contact manner, the previous black toner image is not disturbed.

Thereafter, recharging is performed in the same manner, and a latent image is formed using a magenta signal.
Magenta development, recharging, latent image formation using a cyan signal, and cyan development are repeated.

At this time, the yellow toner and magenta toner pass through the laser light, so if you expose that part of the photoreceptor as necessary, the static electricity will be removed from that part of the photoconductor, and the magenta and cyan toner will be placed on top of the yellow toner, and the cyan toner will be placed on top of the magenta toner. You can layer toner. After the last cyan toner image is formed, just before the leading edge of the toner image reaches the transfer conveyance section,
The transfer conveyance unit 60 is brought into a state of being lightly pressed against the photoconductor 11, and the paper 56 enters between the photoconductor 11 and the belt 63 by the registration roller 54 at the timing when the leading edge of the toner image and the leading edge of the paper 56 match. It is fed as follows.

While the toner image is transferred to the paper 56 by the electric field generated by the second charger 64, the paper 56 is conveyed while being attached to the belt 63, but since the curvature of the roller 62 is large, it separates from the belt 63 and is separated from the fixing paper discharge section. Enter. At this time, in order to prevent the toner image on the paper 56 from being disturbed by the separation charge generated on the paper 56 when it is separated from the belt, negative corona is sprinkled from above by a third charger.

The toner image on the paper 56 is fixed when it passes through the fixing paper discharge section and is then stacked on the paper discharge tray. - The untransferred toner image remaining on the photoconductor 11 is positively charged by the fourth charger 86, which starts operating just before the leading edge approaches, and almost simultaneously moves into contact with the photoconductor 11. The electric field applied between the fur brush 81 and the photoreceptor 11 moves the photosensitive material to the fur brush 81 while being rubbed by the fur brush 81 . Furthermore, the toner inside the fur brush 81 is collected by a collection roller 82.
Due to the electric field applied between the fur brush 81 and the fur brush 81, the vibrator 8 is transferred to the collection roller 82 and dropped onto the collection screw 83.
4 and placed in the collection box.

The surface of the photoreceptor 11 is thereby cleaned, and on the other hand, the charge is removed by the charge removal lamp 87, and the photoreceptor 11 is returned to its initial state and ready for the next copy.

On the other hand, toner that accumulates in small amounts on the belt 63 of the transfer conveyance section 60 due to operational errors or normally is cleaned by a cleaning blade 65 and collected in a collection box 63.
Dropped within 6.

The above is an overview of the overall configuration and operation of a digital color copying machine to which the present invention is applied. Next, the structure and operation of the developing section of this digital color copying machine will be explained in detail.

FIG. 2 is a detailed view of the photoreceptor 11 and developing section 30 in FIG. 1, and this figure shows the M developing device 32 in a developing state.

Each developing device 31, 32, 33, 34 has a developing rack 41.
This figure shows a part of the developing rack 41 cut away. Reference numeral 101 is a handle for pulling out the developing rack from the main body. Color developer 3L32
．． Reference numeral 33 denotes a return spring (not shown) installed in the developing rack 41 so that it returns to the position like the Y developing device 31 and C developing device in FIG. 2 in a free state without applying any external force.
is energized by Furthermore, when the developing device is supported by a shaft 39 and is not pushed by the eccentric cam 38, it is in a position as shown in FIG. 2 due to its own weight.

Eccentric cams 35, 36, 37, 38 are installed in the main body of the copying machine, and the stored developing device is connected to each leaf spring 44, 45, 46.
．． It can be pressed from the rear via 47, approximately 18
By repeating rotation stop every 0 degrees, the developing device can be in a pressed state and a released state.

Next, the structure and operation of the photoreceptor portion of this digital color copying machine will be explained in detail. FIG. 3 is an axial cross-sectional view of a portion of the photoreceptor. 121 is a photoreceptor drum with Se on its surface.
A photoconductive layer of the system is deposited, and the inner diameter portions at both ends form a tapered cylinder as shown in the figure. The tapered portion has a rear flange 122 and a front flange 123, respectively.
is fitted, and this flange 122, 123 is the shaft 124
By engaging with the photosensitive drum 121, the photosensitive drum 121 becomes unsupported. The shaft 124 is rotatably supported at both ends by bearings 125 and 126 by a rear side plate 127 and a front lid 128, respectively. The front lid 128 further includes a front side plate 129.
It is fixed by thumbscrews 130 and 131.

- A pin 132 is installed in the blade shaft 124 at the position of the rear flange, and both ends of this pin 132 are engaged with grooves 133 carved in the rear flange 122, so that the rear flange 122 and the shaft 12 are connected to each other.
It is a roundabout between 4 and 4. A screw 134 is cut into the other portion of the shaft 124, and a nut 135 is engaged with this screw. When the nut 135 is tightened, a force is applied between the bottle 132 and the nut 135 in a direction in which the rear flange 122 and the front flange 123 approach each other, and the photoreceptor drum 1
21 is fixed with scissors. A gear 136 is integrally fixed to the rear flange 122 and is rotationally driven by a drive gear 137. - A guide 138 is fixed on the opposite side of the edge flange 122 slightly inside the outer shape. The guides 138 are fixed to the surface of the rear flange 122 at three positions equally divided into arc shapes. The other side of the guide 138 is integrally fixed to a stop plate 139, and its tip further extends to pass through a hole in the front lid 123 and attach to the front lid 1.
It is close to 2B. The center of the stop plate 139 is the shaft 124
It is recessed so that it can be slid. A retaining E-ring 140 is attached to the shaft 124 on the outside of the stop plate 139.

The structure of the photoreceptor portion has been described above. Next, the operation of this structure will be explained. Normally, they are in the state shown in FIG. 3, but as mentioned above, the rear flange 122, front flange 123, and photosensitive drum 121 are pressed into contact with each other in the axial direction at the tapered portions. The photosensitive drum does not shift or wobble with respect to each flange. For example, as shown in FIG. 2, when a developer of a color to be developed is pressed against the photoreceptor 11, the photoreceptor drum 121 receives pressure in the circumferential direction or radial direction, and as explained in FIG. A similar pressure is applied when the conveying section 60 or the cleaner 80 approaches the photoreceptor. In our experiments, especially when there is a radial gap between the photoreceptor drum 121 and the rear flange 122 or the front flange 123 as in the conventional example, when the photoreceptor drum receives such an external force in the radial direction, The photoreceptor drum rattled against the flange, causing color misalignment and was expensive. On the other hand, with the structure shown in FIG. 3, a high-quality image without color shift or unevenness was obtained.

Next, the operation when replacing the photoreceptor drum will be explained.

When removing the photoconductor drum for replacement, remove thumbscrews 130 and 131 one by one, and then open the front cover 128.
Remove it from the front plate. This poetic sentiment 124 is bearing] 25
The receiver is supported by the portion 141. Next, Natsuto 13
5 and remove the front lid 123 from the shaft 124. At this time, the photosensitive drum is slightly tilted, but is supported by the guide 13B. Thereafter, the photosensitive drum is pulled out to the right in FIG. 3 and out of the apparatus while being guided by the guide 138.

When the photoreceptor drum 121 is separated from the rear flange 122, the falling ffts of the photoreceptor drum 121 is smaller than the distance g between the photoreceptor drum 121 and the end of the front side plate 129, so the photoreceptor drum 121 rubs against the front side plate 129. Never. Further, since the tip of the guide 138 extends almost to the position of the front side plate 129, the rear end of the photosensitive drum 121 comes off the guide 138 when the entire body has almost come out from the front side plate 129, and Photoreceptor drum 12 at the end
The structure makes it difficult to guess 1. Next, when a new photosensitive drum is installed, the operation is reversed.

However, when inserting the photoreceptor drum, when the end reaches the rear flange 122, the height t of the tapered portion is larger than the gap S between the photoreceptor drum and the guide 13B, so it will smoothly reach the position shown in FIG. 3. It's ready to go.

The above is an explanation of the configuration and operation of one embodiment of the present invention.
As mentioned above, the photoconductor drum and flange are butted against each other at the tabular part, so simply tightening the front flange with a nut will securely fix the gap between the photoconductor drum and the flange, preventing the photoconductor drum from wobbling or speeding up. No changes occur. Therefore, it is possible to obtain a high-quality image without jitter or unevenness, and without color shift. Further, since the photoreceptor drum and the flange do not need to be fixed with special adhesive or other means, when replacing the photoreceptor drum, only the photoreceptor drum can be easily removed and disposed of, and maintenance costs are also reduced. Furthermore, since the gap between the guide for inserting and removing the photoreceptor drum and the photoreceptor drum when the photoreceptor drum is installed is smaller than the height of the taper, the photoreceptor drum can be installed smoothly when the drum is inserted.

In addition, the guide extends through the front flange to the position of the front plate, so when removing or inserting the photoreceptor drum, there is no need to hit the photoreceptor drum against anything around the photoreceptor drum, such as the front plate, and damage it during maintenance. It is a highly functional device.

As described in detail, according to the present invention, it is possible to securely hold the photoreceptor, and therefore, it is possible to produce high-quality images without jitter or unevenness, and especially in the case of color, without color shift. Moreover, it provides an excellent color image forming apparatus that is easy to maintain, such as replacing photoreceptors.

[Brief explanation of the drawing]

FIG. 1 is a side view of a digital color copying machine according to an embodiment of the present invention, FIG. 2 is a side view showing details of its developing section, and FIG. 3 is a sectional view showing details of its photoreceptor. , FIG. 4 is a diagram showing a conventional method of holding a photoreceptor. l...reading section, 2...writing section, 11...
Photoreceptor, 30...Developing section, 31...Y developing device, 32
...M developer, 33...C developer, 34...K developer, 35-3 days...eccentric cam, 121...photosensitive drum, 122...rear flange, 123... ...Front flange, 124...shaft, 35...narato, 32...bin, 1 38...guide.

Claims (3)

[Claims] (1) A photoreceptor drum that rotates while holding an electrostatic image, a plurality of developing means that sequentially form toner images of a plurality of colors on the photoreceptor drum, and an end portion of the photoreceptor drum. a flange that holds the photoreceptor drum together, and a photoreceptor guide that guides the photoreceptor drum when the photoreceptor drum is inserted or removed and normally has a gap between the photoreceptor drum and the photoreceptor drum; A color image forming device in which either or both of the end of the drum and the mating part of the flange are tapered. (2) The color image forming apparatus according to claim 1, wherein a gap between the photoreceptor drum and the photoreceptor guide is smaller than a thickness of the taper. (3) The color image forming apparatus according to claim 1 or 2, wherein a portion of the photoreceptor guide extends through the flange to the outside of the photoreceptor drum.