JPH0749485Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention is to carry toner images of different colors formed on a plurality of photoconductor drums by a transfer belt that rotates in contact with each of the photoconductor drums in order. The present invention relates to a color image forming apparatus that performs superposition transfer on a transfer paper that is conveyed.

2. Description of the Related Art As shown in FIG. 3, a color image forming apparatus using an electrostatic photography process such as a color copying machine or a color printer has photosensitive drums 14 arranged in parallel with each other and in contact with one plane on the lower side. And a transfer belt 21 that rotates in contact with these photoconductor drums in sequence, and toners of different primary colors formed on the photoconductor drums, namely, three primary colors of black and cyan, magenta, and yellow. 2. Description of the Related Art There is known a color-separated image superposition transfer type image forming apparatus in which an image is superposed and transferred onto a transfer paper carried and conveyed by a transfer belt 21 and fixed to obtain a full-color recording.

The color copying machine shown in the figure has a document reading section 1, an image processing section 2 for electrically processing each color image information signal read by the original reading section 1, and an image processing section for processing the black, cyan, magenta, and yellow. The printer unit 3 forms an image based on a signal to be developed in each color and transfers the image onto a transfer paper to form an image.

In the document reading section 1, the document placed on the contact glass 4 is illuminated by a white lamp 5, and the reflected light is incident on a color separation prism 10 via mirrors 6, 7, and 8 lenses 9 and blue, green. , Separated into three colors of red, CCD11B, 11 respectively
It is read by G and 11R and output as a digital signal.

The output is subjected to necessary processing in the image processing unit 2 and converted into an image information signal to be developed in each color of black, cyan, magenta, and yellow, and each photosensitive drum 14BK of the printer unit,
Laser writing devices 12BK, 1 attached to 14C, 14M, 14Y, respectively
Input to 2C, 12M, 12Y. (Subscripts BK, C, M,
Y represents a member for forming an image developed with black, cyan, magenta, and yellow. In addition to the above, each photoconductor drum 14 is provided with a charging charger 15, a developing device 16, and a transfer charger 17, and each color recording device 13BK, 13C, 13M, 13Y is provided by these laser writing device 12 and process element devices.
Is formed.

The four color toner images formed on the respective photoconductor drums 14 by the known electrostatic photography process by the respective recording devices are fed to the paper feeding section.
A sheet feeding roller 18 from 19 passes the registration rollers 20 at the same timing to superimpose it on the transfer sheet fed to the transfer belt 21 under the action of the transfer charger 17, and the transfer sheet after the transfer is the transfer belt. Separated from 21, the fuser roller pair 22
A full-color image is fixed on the paper and discharged to the outside by the discharge roller 23.

Now, as in the above-mentioned color copying machine, a plurality of photoconductor drums are arranged in parallel, and toner images of different colors formed on the photoconductor drums are sequentially brought into contact with the respective photoconductor drums to be transferred. In the full-color recording and forming apparatus that superimposes and transfers the color images, there is a problem of color misregistration in which colors are not reproduced due to the transfer positions of the respective color images being shifted from each other. In order to prevent color misregistration due to parallel displacement of each color image, the shafts of the respective photoconductors are accurately supported by the rear side plate and the front side plate of the machine frame so that the distance between the respective photoconductors maintains a strict accuracy.

By the way, when the front and rear ends of the shaft of the photoconductor drum are supported by the side plates, as shown in FIG.
When it is mounted with an inclination of only, a straight line image which should be perpendicular to the transfer direction of the transfer paper P is written on the photoconductor 14 with an inclination of θ, and when transferred to the transfer paper P, the inclination is 2θ.
The resulting line shift Δx becomes 2Δx, resulting in color shift.

As a means for solving the problem of color misregistration due to the inclination of the photoconductor in the horizontal plane, for example, Japanese Patent Laid-Open Nos. 62-229,264 and 63-185,151 disclose one end of the shaft of each photoconductor drum. It is supported by the rear side plate of the machine frame, and the other ends of the shafts are individually attached to the face plate fixed to the front side plate through the adjusting means that can adjust the shaft support position in the transfer paper conveying direction. An apparatus is disclosed which is capable of holding the degree of accuracy accurately and thereby preventing color shift.

This device is shown diagrammatically in FIGS. 5 and 6.

The photoconductor shafts 28BK, 28C, 28M, 28Y are each supported at the rear end by the rear plate 124 of the machine frame, the front end is provided for each color recording device, and the upper end is swingably attached to the front plate 24 by a reference pin. The unit face plates 25BK, 25C, 25M and 25Y are rotatably supported via bearings. (To avoid cleverness in the figure,
Only 25BK is shown. ) Therefore, the photoconductor shafts 28BK, 28C, 2
8M and 28Y are cantilevered shafts with the rear end supported in the AB direction, and the position in the AB direction can be adjusted.

The mounting holes 50 are fitted to the positioning pins 29 provided on the left and right sides of the machine frame front side plate 24, fixed by the nuts 40, and the device face plate 31 positioned and attached to the front side plate 24 is provided for each photoconductor shaft. Position adjusters 30BK, 30C, 30M, 30Y are attached to, and the position of the bearing 34 can be finely adjusted in the AB direction by an adjusting screw (not shown) .Adjust the position of each bearing in advance, Each photoconductor shaft is fitted to this, and the face plate 31
By fixing to the front plate 24, the photoconductors are parallel to each other. In order to enable the above operation, as shown in FIG. 6, the positioning pin 29 is prevented from engaging with the hole 50 of the face plate 31 with the shaft end of the photoconductor fitted in the bearing 34 of the position adjusting device. ing.

However, in this mounting device, as described above, the shaft of the photoconductor is a cantilever shaft, and the shaft is tilted.
It is troublesome to match the positions of the mounting holes 50 of 29 and the device face plate 31. Further, this disagreement may occur even when the positional relationship between the front side plate 24 and the rear side plate 124 is displaced due to distortion of the device structure or the like. Pin the device face plate 31 in such a state
When fitting and mounting to the 29, the device face plate 31 is searched for the fitting position of the pin and the hole while correcting the position in the AB direction, but the pin and the hole are made to a dimensional tolerance that reduces rattling. Therefore, its operation is extremely difficult. Further, in the worst case, the axis of the photoconductor may be bent during the position correction work in the AB direction, which causes a positional deviation due to rotational shake of the photoconductor.

SUMMARY OF THE INVENTION In view of the above-mentioned problems when adjusting the parallelism of the photoconductor of the image forming apparatus having the above-mentioned configuration, the present invention is easy to mount on the device face plate and does not require the photoconductor shaft. An object of the present invention is to provide an image forming apparatus that does not easily bend.

Means for Achieving the Object In order to achieve the above object, the present invention provides an image forming apparatus having the above-described configuration, in which a face plate is provided with a shaft supporting hole for supporting a shaft on the other end side of each photosensitive drum. After the fitting of the positioning pin and the mounting hole, the shaft support hole and the other end side shaft of each of the photosensitive drums are fitted and mounted,
The positioning pin is characterized in that its tip is set so as to protrude from the tip of the other end side shaft of each of the photosensitive drums.

With the above configuration, after adjusting the bearing position of the adjusting device for each photoconductor shaft provided on the device faceplate, the mounting hole of the faceplate is inserted into the front plate while the end of the photoconductor shaft is not engaged. Can be engaged with the positioning pins of the. In this state, the end of each photoconductor shaft is appropriately chamfered, so that each photoconductor shaft is naturally fitted to the bearing by further pushing the face plate deep into the positioning pin.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the conventional apparatus described in FIGS. 5 and 6 above.

Therefore, the same members as those of the conventional device are designated by the same reference numerals.

In FIG. 1, the pin 129 is provided with a positioning portion 129a having a diameter that fits into the positioning holes 50 formed at both ends of the device face plate 31, and the length of the positioning portion 129a. Is longer than the length of the positioning portion of the pin 29 of the conventional device. As shown in FIG.
The front end portion of the positioning portion 129a of 129 has the positioning hole 50 of the face plate 31.
In the state in which the photoconductor shafts 28BK, 28C, 28M, and 28Y are engaged with each other, the tip ends of the photoconductor shafts 28BK, 28C, 28M, and 28Y are separated from the inside of the face plate 31. Other configurations are the same as those of the conventional device.

Since this device is configured as described above, when the face plate 31 in which the position of each bearing 34 is adjusted in advance is fitted to the positioning pin 129, the vicinity of the tip of the positioning portion 129a of the positioning pin 129 engages with the mounting hole 50. In the state, each photoconductor shaft 28BK,
Since the tip ends of 28C, 28M, and 28Y are separated from the face plate 31, the work of positioning the face plate 31 in the AB direction is easy. When the face plate 31 is further inserted into the back side (direction of arrow C) along the pin 129, the photoconductor shafts 28BK, 28C, 28M and 28Y in the cantilever state having an appropriate chamfered portion at the tip end correspond to the corresponding bearings 34. The photoconductor is positioned as it is inserted naturally.

Further, as shown in FIG. 2, by making the portion of the face plate 31 where the mounting hole is formed into a boss shape as shown by reference numeral 150,
The length of the hole becomes longer, the holding length when the positioning pin 29 is inserted can be made longer, and the device face plate 31 is prevented from inclining in the direction shown by the arrow D-E in the figure, and the photosensitive member thereafter. The shafts 28BK, 28C, 28M, 28Y can be smoothly inserted.

As described above, according to the present invention, in the image forming apparatus having the above-described structure, it is possible to easily mount the face plate that supports the front end of the photoconductor shaft and easily insert the photoconductor into the position-adjusted bearing. Therefore, the working efficiency is improved and the bending of the photoconductor shaft is prevented.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view showing a structure of a front end support portion of a photoconductor shaft of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a horizontal sectional view showing a modified embodiment thereof, and FIG. FIG. 4 is a cross-sectional view showing the overall structure of an example of an image forming apparatus, FIG. 4 is an explanatory view for explaining color misregistration due to the inclination of the photoconductor drum, and FIG. 5 is an example of the structure of a conventional photoconductor shaft front end support portion. FIG. 6 is an exploded perspective view of FIG. 14BK, 14C, 14M, 14Y ... Photoconductor drum 24 ... Front plate 28BK, 28C, 28M, 28Y ... Photoconductor shaft 31 ... Face plate, 34 ... Bearing 50 ... Mounting hole, 129 ... Positioning pin 129a ... Positioning part

Claims (1)

[Scope of utility model registration request] 1. A plurality of photosensitive drums, which are in contact with each other on one plane on the lower side and are arranged in parallel with each other, and a transfer drum which sequentially slides in contact with these photosensitive drums to carry and convey a transfer sheet. A color image forming apparatus for superposing and transferring toner images of different colors formed on the above-mentioned photoconductor drums onto a transfer paper carried and conveyed on the above-mentioned transfer belt. Of the image forming apparatus, one end of which is supported by one side plate, and the other end of which is supported by a face plate attached by fitting a mounting hole into a positioning pin implanted in the other side plate. A shaft support hole for supporting the shaft on the other end side of the photosensitive drum is provided, and after the positioning pin and the mounting hole are fitted, the shaft support hole and the other end side shaft of each of the photosensitive drums are Above position so that it can be fitted and installed The image forming apparatus is characterized in that the tip of the deciding pin is set so as to protrude from the tip of the other end side shaft of each of the photosensitive drums.