JP2000284639A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring about general satisfaction in image quality, recording speed and maintainability with the size of a device that can be utilized on a desk top by constituting a photoreceptor belt that is hung long in a vertical direction to be able to be extracted toward a top part of the device. SOLUTION: In this electrophotographic device, the photoreceptor belt 1 is installed vertically, each of developing devices 3 to 6 are lined up vertically along the photoreceptor 1 on one side, an intermediate transfer body drum 2, a cleaning device 13 for the photoreceptor belt, an electrifying device 11 and a laser exposure device 12 are stacked up in this order on the other side, a paper tray 21, paper carrying systems 15 and 17 and a fixing device 20 are installed below the developing devices 3 to 6 and the intermediate transfer body drum 2. As for the size of the device, a paper ejecting side of the recording paper is brought up front taking into account the paper sizes from an A4 size to an A3 size and side width is one where it can be sufficiently loaded onto a desk top taking into account space for a controller and a motor, etc. The device is constituted so that the photoreceptor is to be rotated 4 times enabling a high speed recording. Furthermore, the device is constituted so that a photoreceptor-developing device unit is inserted from above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording a color image, and more particularly to a compact color image recording apparatus utilizing an electrophotographic process.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for recording a color image from image information such as a computer, there is an electrophotographic recording apparatus utilizing an electrophotographic method. The electrophotographic method has a drawback that, because of a large number of printing processes, the configuration is complicated, the handling of the device is poor, and the entire device is easily enlarged. In particular, if the four developing machines are arranged around one photosensitive drum, the configuration of each developing machine is different.
This leads to an increase in the diameter of the photosensitive drum along with the complexity of the apparatus, such as the necessity of various types of developing machines. Therefore, a method in which a photoconductor having a relatively small diameter is used and the four developing machines are switched by sliding or rotating is disclosed in, for example, JP-A-2-189562 and JP-B-2-13304.
It is shown in Japanese Patent Publication No. However, in these configurations, a mechanism for moving the developing machine is required, so that the apparatus becomes complicated and the handleability is not sufficient.

On the other hand, a method of arranging three or four developing machines by arranging a photosensitive member in a belt shape and utilizing a flat portion of the photosensitive member has been proposed in Japanese Patent Application Laid-Open No. H2-213884. ing.

[0004]

In a conventional electrophotographic apparatus, when a color image forming apparatus is actually manufactured, it is difficult to satisfy image quality, recording speed, maintainability, and apparatus size comprehensively. However, problems such as a decrease in recording speed and an increase in the size of the apparatus occur. For this reason, although these various schemes have been proposed, a high-quality small-sized color electrophotographic apparatus having a device size usable on a desktop has not yet been provided.

Accordingly, an object of the present invention is to comprehensively configure a photoreceptor, an intermediate transfer body, a printing process such as charging, exposure, development, transfer, and fixing, a paper transport path, and a configuration and arrangement of each unit. It is an object of the present invention to provide a small-sized color electrophotographic apparatus which can easily be used on a desktop and which satisfies the image quality, recording speed, and maintainability comprehensively.

[0006]

According to the present invention, there is provided a photoreceptor belt stretched in a longitudinal direction and a plurality of toner images of different colors formed on the photoreceptor belt. A plurality of developing machines and a toner image formed on the photoreceptor belt are sequentially superimposed to form a color toner image, and an intermediate transfer member disposed on the other side of the photoreceptor belt has a photoreceptor belt. And can be taken out above the apparatus.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing an example of the configuration of a small color image recording apparatus using the electrophotographic process of the present invention.

First, the outline of the operation of each section when a color image is recorded by the present apparatus will be described. This apparatus comprises a photoreceptor belt 1 and an intermediate transfer drum 2. First, a uniform charging is performed on the rotating photoreceptor belt 1 by a charger 11. Next, by the laser exposure device 12,
Laser exposure according to the yellow image pattern is performed,
An electrostatic latent image is formed. The electrostatic latent image is developed by the yellow developing machine 3, and the developed image is transferred to the intermediate transfer drum 2. Subsequently, the photoreceptor belt 1 is cleaned by an eraser and a cleaning device 13 by erasing. The cleaning device 13 is provided with a waste toner box 14 in which waste toner generated by cleaning is collected. Next, after charging again, exposure according to the magenta image pattern is performed.
A magenta image is formed. The magenta image is transferred to be superimposed on the previously formed yellow image on the intermediate transfer drum 2. In this process, the formation of a cyan image by the cyan developing device 5 and the formation of a black image by the black developing device 6 are continuously performed, and an image composed of four colors of yellow, magenta, cyan, and black is formed on the intermediate transfer drum 2. To form In forming these images, the transfer device and the transfer mechanism including the cleaning device 19 around the intermediate transfer drum 2, the transfer roller 17 for transferring the paper to the paper, and the static eliminator 18 are in a non-contact retracting state. Subsequently, a sheet is picked from the sheet cassette 21 and the four-color image on the intermediate transfer drum 2 is collectively electrostatically transferred. The sheet after the transfer is removed by static elimination, heated by the fixing device 20 to mix the toners of the respective colors, and fused on the sheet to complete the full-color image recording.

When the transfer to the sheet is completed, the intermediate transfer drum 2 is cleaned by the cleaning device 1 for the intermediate transfer drum.
9, the residual toner is cleaned, and the waste toner is disposed in the waste toner collection box 1 of the cleaning device 13 for the photosensitive belt 1.
Collected in 4.

Further, the developing devices 3, 4, 5, and 6 are provided with toner storage chamber units 7, 8, 9, and 10, respectively, from which a necessary amount of toner is replenished when the toner in the developing device runs short. You.

In this embodiment, as shown in FIG. 1, a photoreceptor belt 1 is arranged vertically, and developing units 3 to 6 are vertically arranged on one side along the photoreceptor belt 1 to form developing units 3 to 6. The intermediate transfer drum 2, the photosensitive belt cleaning device 13, the charger 11, and the laser exposure device 12 are stacked in this order on the side opposite to the side where the drum 6 is disposed, and the developing devices 3 to 6 and the intermediate transfer drum 2, a paper tray 21 and a paper transport system 1
5 and 17 and the fixing device 20 are arranged.

By arranging as described above, when the paper size is considered from A4 size to A3 size, the total device height including the paper cassette having a height of about 40 mm becomes about 250 to 500 mm, and the recording paper When the paper ejection side is the front, the depth is about 290 mm to 400 mm, and the width is 350 mm to
It can be formed in a size of about 600 mm, and can be sized to be sufficiently placed on a desk.

Next, the reason for the configuration of each part of the internal configuration of the apparatus and the details of the configuration of each part will be described.

In order to construct a color image recording apparatus using an electrophotographic process such as a laser printer, a photoreceptor is provided for each color, and after the charging, exposure and development processes are completed, the image is transferred onto a recording paper. A fixing method is generally used. However, this method has a disadvantage that a photoconductor and an exposure and development unit for four colors are required, and the apparatus becomes large. As another method, a single photoconductor is used, and a recording process of charging, exposing, and developing is performed for each color on the photoconductor, and the process is repeated three to four times to repeat yellow, magenta, and cyan (for four colors, The image is formed by superimposing the images of the basic colors (using black).
The fixing method and the process up to the transfer to the recording paper in the above-described process are set as basic processes, a method of forming a full-color image by superimposing and fixing images of each color on the recording paper, and the method of the present invention. The image after color development is transferred onto an intermediate transfer body, and each color is superimposed on the intermediate transfer body,
There is a method in which the image is transferred onto a recording sheet and fixed when the superposition is completed. Each method has advantages and disadvantages. In particular, in the method using the intermediate transfer member, the influence of the recording paper,
The method using the intermediate transfer member of the present invention is excellent in obtaining a high-quality color image because it is hardly affected by changes in the surrounding environment (especially recording paper is easily affected by changes in the surrounding environment). The device will be described.

The electrophotographic process of the present invention requires many printing processes such as a charging process, exposure process, development process, transfer process, cleaning process, and fixing process of a photoconductor as a photoconductive material. For this reason, there is a disadvantage that the size of the apparatus is likely to be large. In order to solve this drawback, the present invention minimizes the size of each process, and achieves miniaturization by devising an arrangement configuration, and enables high-speed printing.

The apparatus according to the embodiment of the present invention shown in FIG. 1 has a configuration in which the photosensitive member is rotated four times, and the recording speed is 5 pages per minute (A4 recording) when recording a full-color image, and is per minute when recording a single color. Although the number of pages is 20, it is possible to perform higher-speed recording with this configuration. That is, the recording speed of a single color according to the configuration of FIG. 1 is very high, from several tens of pages per minute to about 100 pages per minute. Therefore, even if the photoconductor is rotated three to four times for color printing, it is possible to record several pages per minute to several tens of pages per minute.
This speed is considerably higher than that of a color image recording apparatus using another method such as an ink jet method or heat sensitivity, and is also a sufficient recording speed for a small-sized color image recording apparatus used on a desktop. .

A color image has a larger amount of information than a single-color image. Since a color image recording apparatus is required to have high image quality, it is considered that a recording density of 400 to 600 dpi (a unit indicating the number of dots per inch) or more is required. When the paper size is A4 and the number of dots on paper at 400 dpi is
It is about 15.5 million. Considering the gradation of three colors and eight bits for each dot, the information amount is 46 MByte. For this reason, a current color printer requires several minutes to several tens of minutes to transfer and convert data in order to perform image recording. It is expected that the conversion transfer time will be increased in the future, but the recording speed of the color image recording apparatus will be the above-mentioned number per minute unless the speed is increased by several hundred to several thousand times or more. About ten to one hundred pages per minute is sufficient. In this sense, a desktop type small color electrophotographic apparatus in which a single photoconductor is rotated a plurality of times is effective. The details regarding the recording speed will be described later.

Next, in the method of superimposing the formed images of the respective basic colors, in the present invention, as described above, the photosensitive belt 1 is used.
When one color image is formed on the intermediate transfer drum 2, the image is transferred onto the intermediate transfer drum 2, the next color image is formed on the photoreceptor belt 1, and the image is sequentially formed on the same intermediate transfer drum 2 Are superimposed and transferred, and after all the colors have been superimposed on the intermediate transfer drum 2, they are transferred onto a recording paper and fixed.

First, regarding the shapes of the photosensitive member and the intermediate transfer member, a belt configuration and a drum configuration can be considered, respectively. Since the belt can be freely selected in its shape, there are few restrictions on the various printing processes arranged around it.However, there is a risk that the belt may meander when driven, and it is necessary to always apply a constant tension. There is a possibility that a mechanism such as a tensioner is required, and slippage may occur during driving.
For this purpose, it is necessary to provide protrusions on both sides of the belt and to select a material for the drive shaft and the inner surface of the belt so that sufficient frictional drive can be obtained. On the other hand, the drum configuration has a simple configuration and is easy to drive, but has a great restriction on the printing process arranged around.

The photoreceptor has a charger, an exposure,
It is necessary to arrange four developing machines together with the cleaning, erasing and intermediate transfer drums. In the case where the intermediate transfer member and the photosensitive member are configured as a drum, it is necessary to increase the diameter of the photosensitive member.In order to prevent this, a single developing device is brought into contact with the photosensitive member. A configuration in which the device is replaced by a slide mechanism or a rotation mechanism is required, and an increase in the size of the device is inevitable.

Further, when a plurality of developing machines fixed around the drum are arranged, the configuration of each developing machine is different. In order to simplify the manufacturing cost and the configuration, it is preferable that the three or four developing machines used are the same. For this reason, a configuration in which the photoconductors are belt-shaped and the same developing machines are arranged in parallel is important for realizing a compact color electrophotographic printer.

The process disposed around the intermediate transfer member is such that the same process member (developing machine in the case of the photoreceptor) does not exist as the photoreceptor and the process member disposed around the photoreceptor. Less is. Considering that the photosensitive member is a belt as described above, it is desirable that the intermediate transfer member has a drum configuration that is more stable and easier to drive than the belt. For this reason, in the present invention, a recording apparatus configuration in which the intermediate transfer drum 2 and the photosensitive belt 1 are combined is adopted.

In order to reduce the size of the color electrophotographic apparatus, it is necessary to first reduce the size of the intermediate transfer drum 2 and the photosensitive belt 1. In the method using the intermediate transfer drum of the present invention, the outer peripheral length must be longer than the length of the sheet on which recording is performed in the transport direction. If the A4 horizontal direction (short direction) is the transport direction, the required length of the outer periphery of the intermediate transfer member is 210 mm or more. If the A4 vertical direction (long direction) is the transport direction, the required length of the intermediate transfer member is 297 mm or more. It is. Further, when considering an apparatus capable of recording up to A3, the required length of the outer periphery of the intermediate transfer body is 4 in A3 vertical direction feeding.
20 mm or more. From this, when the intermediate transfer member is a drum, the drum diameter is 67 mm or more in A4 horizontal feed (= 2
10 / 3.14), 95 mm or more in A4 vertical feed (= 297
/3.14), 134mm or more in A3 vertical feed (= 420 /
3.14) Required.

The photoreceptor belt 1 is formed by bonding sheet-shaped photoreceptors in a loop shape, and thus has a seam. In order to record while avoiding the seam of the photoreceptor, the position where the seam of the photoreceptor and the intermediate transfer drum 2 are in contact with each rotation of the photoreceptor belt 1 is the same. The circumference of the intermediate transfer drum 2 needs to be longer than the value. For this purpose, the photoreceptor belt 1 needs to have a length that is a positive multiple of the outer circumference of the intermediate transfer drum 2. FIG. 2 is a diagram showing a positional relationship between the photosensitive member and the surface of the intermediate transfer drum when the rotation period of the intermediate transfer drum 2 is equal to the rotation period of the photosensitive belt 1 (1 time). In the case of FIG. 2, when the seam position of the photoconductor is set to 0 degree, considering the area as ± 10 mm, the color images can always be matched without overlapping the seam portion. FIG. 3 shows a case where the photosensitive belt 1 is longer than the intermediate transfer drum 2. As shown in the figure, if the image of the second color is to be superimposed on the image of the first color transferred to the intermediate transfer member, the image of the second color must be created at the seam portion of the photoconductor, and a beautiful image can be created. Disappears. In order to avoid this, the rotation of the photosensitive belt 1 and the rotation of the intermediate transfer drum 2 are controlled, respectively. If the image forming position on the photosensitive belt 1 is the same, the rotation speed of the intermediate transfer drum 2 is changed. After the alignment, it is necessary to transfer, and the configuration and control become complicated, which is not suitable for downsizing the apparatus.

Although it is possible to apply a photoreceptor to the seam portion to make the photoreceptor seamless, the photoreceptor at the seam portion is liable to be deteriorated when rotated many times. For this reason, it is desirable to use the photosensitive belt 1 except for the joint portion, and it is desirable that the length of the photosensitive belt 1 be a positive multiple of the length of the intermediate transfer drum 2.

Even when a seamless photosensitive member which does not cause deterioration at the joint portion is used, if the length of the photosensitive belt 1 is not a positive multiple of the intermediate transfer drum 2, the photosensitive belt 1 It is known that the rotation cycle of the intermediate transfer drum 2 and the rotation cycle of the intermediate transfer drum 2 deviate from each other, so that the positioning accuracy when the images of the respective colors are superimposed deteriorates.

Further, when the surface of the photosensitive member is damaged or deteriorated, the length of the photosensitive member belt 1 is
If it is not a positive multiple of, the rotation period of the photosensitive member and the intermediate transfer drum 2 is shifted, so that the position where the damaged portion or deteriorated portion affects the final image differs for each image of each color. For this reason, the number of locations affected by scratches and deterioration occurring in the final image is greater than when the length of the photosensitive belt 1 is a positive multiple of the intermediate transfer drum 2. Further, when the length of the photoreceptor belt 1 is a positive multiple of the length of the intermediate transfer drum 2, even if there is a degraded portion in the characteristics of the photoreceptor surface, occurrence of abnormal image density in the degraded portion is the same for each color. Therefore, the area only has a density abnormality, but if the image of each color shifts, the hue of the image at that position changes. For these reasons, it is desirable that the photosensitive belt 1 is a positive multiple of the intermediate transfer drum 2.

From the above, the diameter of the intermediate transfer drum 2 for performing A4 recording is about 70 to 120 mm,
In A3 recording, about 150 mm is appropriate. If the outer circumference of the photoreceptor belt 1 is one time that of the intermediate transfer drum 2, the length of the photoreceptor belt 1 for performing A4 recording is about 220 to 380 mm, and about 47 to 47 mm in A3 recording.
It is about 0 mm. If the outer circumference of the photosensitive belt 1 is twice as large as the intermediate transfer drum 2, the length of the photosensitive belt 1 for A4 recording is about 440 to 760 mm.
In A3 recording, it is about 940 mm. As described above, when the length of the photosensitive belt 1 is twice as long as the outer circumference of the intermediate transfer drum 2, a considerably long photosensitive belt 1 is required. Therefore, in order to realize a compact color electrophotographic apparatus,
It is important that the length of the photosensitive belt 1 is the same as the outer peripheral length of the intermediate transfer drum 2.

Roller 100 for stretching photoreceptor belt 1
If the diameter is too small, the deterioration of the photoreceptor belt 1 is accelerated. Therefore, the diameter b of the roller 100 needs to be at least 10 to 20 mm. As shown in FIG.
When the photoreceptor belt 1 is stretched with two 0 mm rollers 100, the length a of the linear portion of the photoreceptor belt is about 78 to 16 on one side.
0 mm (for A4 recording) and about 200 mm (for A3 recording).

When four identical developing units 3 to 6 are arranged on one side of the photosensitive member, the width of one developing unit is about 25 to 50 mm.
It must be: Approx. 6 even for A3
5 mm or less. Obviously, a very thin developing device is required in consideration of the gap between the developing machines.

As the arrangement of the developing devices 3 to 6 with respect to the photosensitive belt 1, in addition to the method of arranging it on the side of the belt shown in FIG.

In a developing machine using the two-component developing system, the developer composed of toner and carrier must be circulated between the stirring chamber for charging the developer and the developing roll. For this reason, when the developing device is disposed above or below the photoreceptor belt, a mechanism for conveying the developer upward against gravity when supplying and collecting the developer to the developing roll is required.

For example, in a developing machine arranged above the photoreceptor belt, the supply of toner from the toner storage chamber to the stirring chamber and the transfer of the developer from the stirring chamber to the developing roll are in the direction of gravity, so that they are relatively difficult. Easy. However, the peeling of the developer from the developing roll and the transport to the stirring chamber are opposite to the direction of gravity. Therefore, it is difficult to return the developer separated from the developing roll by the blade on the developing roll to the stirring chamber, and the toner stays at a specific position in the developing machine.

For this reason, the construction of the developing machine is as follows. The toner on the developing roll is transferred to a magnet roll disposed above the developing roll, once conveyed upward, separated by a blade, and returned to a stirring chamber disposed on a side surface of the developing roll. Accordingly, in this configuration, it is difficult to configure the developing device having the above-described developing device thickness because the developing device has a large thickness.

On the other hand, as shown in FIG. 1, the method of arranging the developer laterally does not require a structure in which the developer and the toner are conveyed largely upward against the direction of gravity. For this reason, as shown in FIG. 5, while being transported to the developing roll 31 by transport by a stirring paddle (stirring roll) 32, the developer not consumed by the photoconductor is removed from the developing roll 31 by the blade 3.
3 and can be returned to the stirring chamber 34. Further, even when a plurality of stirring rolls 32 are arranged in order to sufficiently stir the developer, unlike the upper arrangement and the lower arrangement, the stirring rolls are arranged in parallel without increasing the thickness of the developing machine. It is possible. Further, the toner can be supplied to the stirring chamber 34 from the side, so that it is relatively easy.

In FIG. 5, the diameter of the developing roll 31 is 2
0 mm, and the thickness of the entire developing machine is about 30 mm. The stirring chamber 34 is disposed below the developing roll 31 and supplies the toner below the developing roll 31. The toner on the developing roll 31 after development is scraped off by the blade 33 and returned to the stirring chamber 34. FIG. 1 showing an embodiment of the present invention.
In order to secure the gap accuracy between the developing devices 3 to 6 and the photosensitive belt 1 and to facilitate the handling of the developing device and the photosensitive belt 1 and to facilitate the replenishment of the toner, 3 to 6 and the photoreceptor belt are integrated into a unit, and the toner storage units 7 to 10 are separated. For this reason, in the developing machine 3 of the embodiment of FIG. 5, a connection portion for connection to the toner storage chamber unit 7 is provided on the side of the stirring chamber. The connecting portion has a lid 35 that opens to the inside of the storage chamber, has a configuration that is easy when connected, and also prevents toner from spilling when not connected and when connected.

FIG. 5 shows the configuration of the toner storage chamber unit 7 connected and the state connected to the developing machine 3. The toner storage chamber has rotating blades 37 made of a PET film or the like having a thickness of about 100 μm. By rotating the rotating blades 37, the toner is transported to the developing device side. In order to prevent the toner from sticking in the toner case, a comb-shaped rotating body 36 made of metal is arranged on the side opposite to the rotating blades. In order to arrange a large amount of toner in a thin space, in the embodiment shown in the figure, two toner chambers in which the rotating blades 36 made of PET film and the comb-shaped rotating body 36 are arranged are arranged in parallel.

The toner supply port for the developing device 3 has a groove 38 for storing toner, and a foaming roller 39.
An exit gate consisting of The toner stored in the outlet groove by the rotating blades 39 is conveyed to the stirring chamber 34 in the developing device 3 by the rotation of the foaming roller 39. Foam roller 3
In the rotation of No. 9, replenishment is controlled so that the output value of a toner concentration sensor (not shown) in the developing machine stirring chamber becomes a predetermined constant value. These controls are controlled by the controller of the main body of the color image recording apparatus shown in FIG. Further, running out of toner in the toner storage chamber is detected by a toner sensor 40 disposed near the foaming roller 39 at the toner outlet. The out-of-toner detection is detected by a controller (not shown) of the color image recording apparatus main body, generates an out-of-toner signal, and requests the operator to supply toner.

Considering the frequency of toner replenishment, the capacity of the toner storage unit 7 seems to require at least a capacity for recording 1000 or more color images having an image density of about 10% for each color. The area of A4 is 623.7cm
² (= 21 cm × 29.7 cm), and the amount of toner required for a sufficient density is generally about 1 mg / cm ² , so the toner consumption per A4 sheet is about 0.06 for each color.
g / sheet. Therefore, in order to print 1000 sheets, a toner amount of about 60 g is required. Since the density when the toner is filled is about 0.3 to 0.4 g / cm ³ , the toner volume is about 150 to 200 cm ³ (= 60 /
0.3 to 0.4). Considering the stable transport of toner in the toner storage chamber and the prevention of toner coagulation,
Generally, the capacity of the toner storage chamber needs to be about two to three times as large. Therefore, the toner storage room is about 300 to 6
A volume of about 00 cm ³ is required. In the toner storage unit 7 in the color image forming apparatus according to the embodiment of the present invention shown in FIG. 1, assuming that the height in the toner storage chamber is about 2.5 cm and the width in the developing roller axial direction is about 28 cm,
The width in the direction perpendicular to the axis of the developing roll is about 4.3 to 8.5 cm. The toner storage chamber unit 7 in the color image forming apparatus of FIG. 1 and the embodiment shown in FIG. 5 is 70 mm wide. Further, the width of the entire developing machine is 120 mm.

Generally, in a non-magnetic one-component type developing machine,
The size can be reduced as compared with the component developing method. In the non-magnetic one-component developing system, there is no stirring chamber to charge the developer by a blade or the like. Therefore, the developing device can be relatively easily arranged above the photosensitive belt 1. However, in a configuration in which the developing device is arranged above the photoreceptor belt irrespective of one-component development or two-component development, the developer easily spills to the photoreceptor side, which is not preferable. In addition, the configuration in which the developing device is disposed below the photoreceptor belt requires the toner to be conveyed counter to the direction of gravity in order to supply the toner to the developing roll even in the non-magnetic one-component developing method, which is structurally difficult. . Further, in a developing device disposed below the photoconductor, there is a high possibility that the toner on the photoconductor drops into the developing device of another color and is mixed. For these reasons, in a configuration in which the photoconductor is rotated a plurality of times and the developing machine is sequentially switched to perform multicolor recording, a configuration in which the developing machine is arranged on the side surface of the photoconductor as shown in FIG. 1 is more effective. It is.

FIG. 6 shows the configuration of a non-magnetic one-component developing machine that can be mounted on the color image forming apparatus of this embodiment. A regulating blade 41 made of an elastic blade is disposed on the upper surface of the metallic developing roll 31. Behind the developing roll 31,
A stirring roll 32 that supplies toner to the developing roll 31 is provided. Above the stirring roll 32, there is a connection portion for connecting to the toner storage unit 7. As the toner storage unit, a unit of the same type as the toner storage unit 7 shown in FIG. 5 can be used.

The toner detecting sensor 43 disposed on a part of the wall of the developing machine 3 which comes into contact with the stirring roller 32 detects a decrease in the amount of toner and supplies toner from the toner storage unit 7. In the embodiment of FIG. 6, the width of the developing machine in a direction perpendicular to the developing roll axis is about 40 mm.

Four developing machines (3 to 6) each having a thickness of about 30 to 40 mm are provided in one linear region of the photosensitive belt 1 stretched vertically.
Are arranged on the other surface of the photoreceptor belt 1, the charging device 11, the laser exposure device 12,
The photoconductor cleaner 13, the erase lamp 325 and the intermediate transfer drum 2 must be arranged. The intermediate transfer drum 2 needs to be provided with an intermediate transfer member cleaner 19 and an image transfer roller 17 for transferring paper. FIG. 7 shows a portion to be transferred from the intermediate transfer drum 2 to a sheet. In the figure, a transfer roller 17 is arranged below the intermediate transfer drum 2, and a toner image is transferred to the recording paper 42 when the recording paper 42 passes therebetween.

In a small-sized apparatus, it is difficult to provide a mechanism for separating the sheet upward by suction or the like. When the sheet is separated after transfer, gravity acts in the direction of separation as indicated by an arrow 43 in FIG. Is desirable. In this sense, the transfer and peeling positions of the intermediate transfer drum onto the paper are determined by the intermediate transfer drum 2
It is desirable to be below.

For each of the above reasons, in the apparatus of the embodiment of the present invention shown in FIG. 1, the length of the linear portion of the photosensitive belt on the developing device side is set to 100 mm, and the internal roller 100 of the photosensitive belt 1 is Were 23 mm and 18.4 mm in diameter.
The diameter of the intermediate transfer drum 2 is 92 mm. The diameter of the internal roller 100 of the photoreceptor belt 1 is set to ５ and の of 92 mm in order to make the rotation fluctuation periods coincide.

Further, for each of the above-mentioned reasons, in the embodiment of the present invention shown in FIG. 1, the photosensitive belt 1 is developed from the side, and the image transfer to the sheet and the peeling position are performed below the intermediate transfer drum 2. Because of the necessity of disposing, the photosensitive belt 1 is disposed vertically longer on one side surface of the intermediate transfer drum, and the photoreceptor belt 1 is transferred below the intermediate transfer drum 2.
A peeling means is provided.

FIG. 8 is a diagram showing a detailed configuration of the photosensitive belt 1 of the present embodiment shown in FIG. The photoreceptor belt 1 has a thickness of 1
It is obtained by depositing aluminum on a 50 μm PET film 305 (polyethylene terephthalate film) and then applying a photoreceptor. The photoreceptor belt has an aluminum deposition layer 304 on a 150 μm PET film, and an insulating layer 303 on the upper portion thereof for maintaining a withstand voltage of the photoreceptor at the time of non-exposure.
Having a charge generation layer 302 and a charge transport layer 3 thereon.
01 is coated with a negatively charged organic photoreceptor. Since the layer thickness of the photoconductor 306 is about 20 μm, the total thickness of the photoconductor belt 1 is about 170 μm. The diameter of the inner roller 100 of the photosensitive belt 1 is 23 mm and 18.4 m.
m is configured to reduce the diameter by exactly this belt thickness.

The end of the belt in the width direction has a protrusion made of a rubber material having a width of about 1.5 mm and a thickness of about 0.5 mm.
Both ends of the internal roller 100 of the photoreceptor belt 1 are tapered, and meandering of the photoreceptor belt 1 is prevented by the protrusion of the photoreceptor belt 1 and the taper of the internal roller 100 of the photoreceptor belt. It is configured as follows.

FIG. 9 shows the charger 11 of the embodiment shown in FIG.
FIG. 3 is a diagram for explaining details of the configuration of FIG. Discharge wire 31
1 and shield case 312 and grid wire 313
Is a scorotron charger. Discharge wire 311
Uses a tungsten wire plated with gold to prevent deterioration due to discharge. It is difficult to handle wire diameters that are too thin or too thick. The diameter of the discharge wire of this embodiment is a 60 μm tungsten wire plated with 3 μm gold, but a discharge wire of about 40 to 100 μm is generally suitable. Shield case 312 and discharge wire 3
If the distance 11 is too short, there is a high possibility that abnormal discharge will occur due to the vibration of the wire during the discharge, and if it is too long, the discharge voltage will increase. The appropriate distance between the discharge wire 311 and the shield case 312 is about 10 mm, and thus the overall width of the charger is about 20 mm. Grid 31-3
It is known that there is a certain relationship between the distance between the photoconductor belt 1 and the surface of the photoconductor belt 1 and the pitch of the grid 313 in order to achieve both efficient charging characteristics and control characteristics. That is, since the grid pitch and the gap between the photoconductor and the grid are appropriately the same, in this embodiment, the grid pitch is 1.5 mm, and the gap between the photoconductor and the grid is 1.5 m.
m. The distance between the grid and the discharge line is about 8.5 mm in this embodiment. The voltage applied to the grid is set at 500 V with the charging potential of the photoreceptor set at 500 V as a target.
V. The voltage application means of the grid can be easily achieved by using a high-voltage zener diode. However, when it is necessary to change the charging potential of the photoconductor, a negative variable power supply must be provided.

In the configuration of this embodiment, the process speed (moving speed of the photoconductor) is 95 mm / s, and the A4 horizontal conveyance is performed. Therefore, the surface area of the photoconductor belt charged by the charger 11 every second is about 285 cm ² . is there. The capacitance of the organic photoconductor having a thickness of 20 μm is about 2.0 × 10 −10 F / cm ² . At this time, the capacity of the surface area of the photoreceptor belt charged in one second is 5.7 × 10 −8 F, and if the charging potential of the photoreceptor surface is 500 V, the current required to be supplied to the photoreceptor belt surface is 2 It is .85 × 10 −5 A, that is, 28.5 μA. In this charger configuration, it is necessary to supply a large amount of current to the grid in order to stabilize the photoconductor surface potential. Assuming that the grid current is about three times the current required on the photoconductor surface, the current flowing between the photoconductor surface and the grid is about 120
μA. In the above configuration, approximately three times the current flows through the shield case 312. For this reason, the corona discharge current is about 500 μA. This current value is a range that can be sufficiently achieved by applying a voltage of 5 to 7 kV to one corona discharge wire 311 having the above configuration. In the device configuration of the present embodiment shown in FIG. 1, this is achieved by an applied voltage of 5.8 kV.

In addition, a roller charging mechanism can be applied within the installation space of the present charger.

FIG. 10 shows the structure of the photosensitive member cleaner 13 used in the embodiment of the present invention shown in FIG. In this embodiment, since the photoreceptor belt 1 is long in the vertical direction, the photoreceptor at the cleaner position also moves substantially vertically. Other methods of cleaning the photoreceptor belt 1 include:
The configuration in which the elastic blade is pressed is the simplest configuration. However, in such a cleaning method, the scraped-down toner falls in the direction of gravity. Therefore, when used on the vertical photoreceptor belt surface having the configuration of the present apparatus, there is a high possibility that the toner leaks out of the cleaner.

In this embodiment, the brush cleaning method shown in FIG. 10 is employed. This method uses a conductive cleaning brush 321 that rotates in a direction opposite to the moving direction of the photosensitive belt 1, and applies a potential higher than the potential of the surface of the photosensitive belt 1 to the conductive cleaning brush 321. Accordingly, the toner is mechanically scraped and the toner is electrostatically sucked.
In the configuration of this embodiment, a voltage of about 600 V is applied to the base aluminum layer 304 of the photoreceptor belt 1 as a base voltage. For this reason, the cleaning brush 321 in the photoconductor cleaner 13 is set to the ground potential. Photoreceptor belt 1
600V as the base voltage for the base aluminum layer 304
The reason why is applied will be described later in detail with respect to the configuration of the intermediate transfer drum. The photoconductor cleaner 13 has a metal roller 322 disposed behind the cleaning brush 321 and applies a positive voltage. As a result, the toner scraped off by the cleaning brush 321
Copied to the side. The metal roller 322 has a blade 3
23 is disposed, and the attached toner is scraped down. The scraped toner is conveyed to the waste toner box 14 in FIG. 1 by the screw conveying mechanism 324 or the like.

In the apparatus configuration of the embodiment of the present invention shown in FIG. 1, cleaning can be sufficiently performed if the outer diameter of the cleaning brush 321 is about 20 to 25 mm. Also the rear metal roller
The 322 used had a diameter of about 10 mm. It is easier to clean the surface of the photoreceptor before cleaning if the charge is sufficiently removed. For this reason, in the present device configuration, a static elimination mechanism using an LED array is disposed below the cleaner, and by integrating the cleaner with the cleaner, handling and assembling work are facilitated.

In the apparatus configuration of the embodiment of the present invention shown in FIG. 1, the brush cleaner 321 is used to stretch the photoreceptor belt 1 vertically, but the photoreceptor belt is slightly inclined as shown in FIG. When the toner scraped off from the belt is configured to be separated from the belt, a cleaner 13 using an elastic blade shown in the drawing can be used. In other parts shown, the same parts as those in FIG. 1 are denoted by the same reference numerals. In this figure, the laser exposure apparatus 1 is used from the viewpoint of effective use of space.
2 are arranged vertically to reduce the size.

The width of the surface of the charger 11 facing the photosensitive member surface is about 20 mm, and the width of the photosensitive member cleaner unit 13 integrated with the erase lamp 325 facing the photosensitive member surface is about 35 mm. It is. These units are arranged such that when the intermediate transfer drum 2 is arranged in parallel with the center line of the roller below the photosensitive belt 1, as shown in the embodiment of FIG. It can be sufficiently arranged on the photoreceptor belt surface opposite to the surface.

Next, the details of the laser exposure apparatus 12 in this embodiment shown in FIG. 1 will be described. Regarding the laser exposure device 12, first, the exposure position is set. However, in the case of a photoconductor made of an organic material as described above, it generally requires 150 ms or more after exposure until a stable electrostatic latent image is formed. .
Therefore, the time from exposure to development is set to about 300 ms. In addition, when the position of the photoreceptor belt fluctuates at the exposure position on the photoreceptor belt 1, the focal length fluctuates, so that the exposure point is blurred and the resolution of the image is reduced. Therefore, it is necessary to perform the exposure position at a position where the behavior of the photosensitive belt 1 is stable, such as on the roller 100 inside the photosensitive belt. The developing device 3 closest to the exposure position in the present embodiment is a roller 1 inside the photosensitive belt.
The photoreceptor belt is arranged at a position apart from the photoreceptor belt 00.
The photoreceptor belt 1 is wound around the roller 100 in a range of approximately 180 degrees. The diameter of the roller 100 is 2
Since the length is 3 mm, the length around which the photosensitive belt 1 is wound is about 36 mm. In order to perform the exposure on the roller 100 at least 300 ms before the development, a maximum of 120 mm / s
(= 36 mm / 0.3 s).
In this embodiment, the angle between the developing position and the exposing position is set to 150 degrees. At this time, the maximum process speed possible is about 100 mm /
s. In this embodiment, the process speed 9
5 mm / s. As described above, since the diameter of the intermediate transfer drum 2 of this embodiment in FIG. 1 is 92 mm, the outer circumference is about 289 mm. At a process speed of 95 mm / s, the intermediate transfer drum 2 rotates about 19.7 revolutions per minute.
In the configuration of this embodiment shown in FIG. 1 in which one full-color image is recorded by rotation, a recording speed of about 5 pages per minute is possible. This is the main reason why the process speed in the above-described color image recording apparatus of the present embodiment is set to 5 pages per minute (A4 recording) for full-color image recording and 20 pages per minute for single-color recording. However, a higher recording speed is possible with the configuration of the present embodiment shown in FIG. 1 by changing the device size or the like.
As described above, this printing speed is sufficient for a small full-color image recording apparatus used for a desktop or the like.

FIG. 12 shows details of an example of the configuration of the exposure apparatus 12 in the embodiment of the present invention shown in FIG. The exposure apparatus 12 according to the embodiment of the present invention employs a laser exposure apparatus 12 for performing high-resolution image recording. In FIG. 12, a laser beam 351 emitted from a laser light source 354 is reflected and scanned by a polygon mirror 353, and the light passes through a reflection type fθ lens 355 and passes through two reflection mirrors 35.
2 and is emitted to the photoreceptor belt surface (not shown). FIG. 13 is a diagram showing a configuration of a scanning unit of the laser exposure apparatus. Semiconductor laser light 35
4 is reflected and scanned by the polygon mirror 353, and the transmission type fθ lens 355 determines the difference in the focal length due to the optical path difference to the surface of the photoreceptor belt 1 to be unexposed and the scanning surface per unit rotation angle of the polygon mirror 353. To correct the fluctuation of the moving distance. In order to secure the laser scanning width of the recorded image width, a long optical path length is required between the polygon mirror and the photosensitive belt. The smaller the scanning angle of the polygon mirror is, the smaller the correction amount based on fθ is, and it is easy to obtain a stable exposure amount in the scanning direction. However, when the scanning angle is small, the distance from the polygon mirror to the photoconductor becomes long, and the size of the entire optical system becomes large. Therefore, the scanning angle is about 100 degrees (5 on one side).
0 degrees) is the limit. Assuming that the scanning angle is 100 degrees, the optical path length required from the polygon mirror to the photosensitive member in order to perform scanning in the A4 longitudinal direction of about 300 mm is calculated by the following equation.

[0060]

(Equation 1)

In equation (1), S0 is the required optical path length, L is the scanning distance, θ is the scanning angle, and X0 is the distance from the scanning center on the scanning surface. Substituting the above values into this equation,
When 0 approaches 0, it becomes about 172 mm. In addition, in order to set the width of the fθ lens to 300 or less, which is the width of the scanning plane, in this setting, it is necessary to set the distance between the polygon mirror and the fθ lens to be equal to or less than the distance obtained by the following equation.

[0062]

(Equation 2)

Substituting the scanning distance L = 300 mm and the scanning angle θ = 100 degrees into Equation 2 results in about 126 mm. Therefore, in this configuration, about 126 mm from the polygon mirror 353
It is necessary to arrange the fθ lens 355 at the following position.

The optical system unit used in the color image forming apparatus of the embodiment of the present invention shown in FIG.
If the width is more than mm, the whole device will be enlarged. However, for a width of about 100 mm that is allowed as the width of the optical system unit, the required laser optical path length in the laser exposure apparatus 12 obtained from the above calculation result is considerably long.

Therefore, in the embodiment shown in FIG. 12, the optical path after scanning is changed to the reflecting mirror 352 in the longitudinal direction of the laser exposure device 12.
Is used twice. At this time, FIG.
In the configuration in which the fθ lens as shown in FIG.
The first reflected light after passing through the θ lens must not enter the fθ lens again. For this reason, it is necessary to increase the first reflection angle, and the size of the laser unit in the thickness direction increases. Therefore, in the configuration of the present embodiment shown in FIG. 12, the shape of the first-time reflection mirror is processed into a shape having fθ characteristics. In this configuration, since the angle of reflection from the first reflection mirror (mirror having fθ characteristics) can be reduced, the optical path length can be secured without increasing the thickness of the optical system in the thickness direction. Such fθ mirror is formed by plastic shape molding.
A mirror having a shape (a free-form surface irrespective of a spherical surface, an aspherical surface, an object, or an object) having all characteristics can be relatively easily created while being easily formed by evaporating aluminum or the like.

FIG. 15 shows another embodiment of the optical system. Behind the polygon mirror 353, a multiple folding mirror 357 having a parallel mirror for internally folding the laser light in multiple stages is arranged. The multiple return mirror 357 is a mirror formed by depositing aluminum or the like on the surface of a plastic or glass block. A long optical path can be ensured because the laser light is reflected a plurality of times inside the multiple folding mirror. In such a multiple folding system, since the angles at which the mirror enters the mirror are different between the center part and both ends of the image, a difference occurs in the attenuation state of the laser. To cope with this, in the example of FIG. 15, a polarization control unit 356 that polarizes the laser light before entering the multiple folding system is arranged. Depending on the polarization direction of the laser, the difference in attenuation after passing through the multiple folding mirror 357 can be corrected. In addition, laser light 3 on the photoconductor
In order to correct the attenuation at the exposure position 51, the laser light source 354 is synchronized with the rotation of the polygon mirror 353.
For example, a method of controlling the amount of light emission of the light emitting element can be considered.

By the above means, the laser exposure apparatus 12 in the embodiment of the present invention shown in FIG. 1 was made about 100 mm wide and about 30 mm high. As a method of reducing the size of the optical system, it is also possible to use a generally known LED array or a liquid crystal shutter type optical system. However, at present, the laser exposure method is more advantageous in terms of definition and stability of exposure light amount.

Next, the developing machines 3 to 6 are arranged in a line on the linear portion of the photosensitive member as described above. When a color image is formed, these developing machines must perform contact and retraction one by one in order in accordance with each rotation of the photoconductor. Further, in the two-component developing system, in order to realize stable high-quality image development, a gap between the developing roll and the photoconductor at the time of development is required to have a high gap accuracy of the order of 100 μm. In the configuration of the present embodiment, in order to maintain a high gap accuracy between the photoconductor and the developing device, the four developing devices and the photoconductor belt are integrally unitized. Further, in this embodiment, in order to facilitate toner supply, the toner cassette is provided separately from the developing device and the photoconductor unit so that the toner can be supplied independently.

FIG. 16 shows the details of an example of the developing device-contacting mechanism of the developing device and the photosensitive member unit in the present embodiment.
The developing machine 3 has a developing roller 31 on a developing roller shaft 398, and a cam mechanism having a groove on a part of the outer periphery on the photosensitive belt 1 side. These four cams 392
Are connected by gears 393 and 395, and when incorporated in the image forming apparatus, the drive mechanism on the image forming apparatus side rotates the end gear by a specified angle via a drive source connection gear 394, In this order, four developing machines are in contact with the photoconductor. FIG. 16 is a diagram in which a part of a gear arranged above the cam is cut away in order to write the cam. Basically, there are four positions where the developing devices of each color are in contact with one by one and positions where all the developing devices are retracted from the photoconductor. At the time of non-printing, the cam mechanism is set so that all the developing machines are retracted from the photoconductor, and at the time of printing, each developing machine is controlled so as to come in contact with the photoconductor and develop. A mark 396 is provided on a part of the gear connected between the developing device and the photoconductor unit, and the position of the mark 396 is detected by a sensor (such as an optical sensor) 397 provided on the image forming apparatus main body side. Developing device retraction mechanism controller on main unit (not shown)
Identifies a developing device that is in contact with the photoconductor, and controls contact and retraction of each developing device.

In a two-component developing machine, the gap accuracy during development is very important. In the configuration shown in FIG. 17, since the photoconductors are located on the surface of the roller 100 inside the photoconductor, the behavior of the photoconductor is stable and the gap can be easily maintained.

However, since the two developing machines at the center are located on the flat belt portion, it is necessary to arrange the guide member 406 as shown in FIG. Although the illustrated guide member 406 has a flat plate configuration, it is also possible to use the rotating roller 413 as a guide member as shown in FIG.

A description will be given of the contact and retraction structure when a non-magnetic one-component developing machine is used as the developing device. Non-magnetic 1
In the component development, it is not necessary to maintain a constant gap accuracy at the time of development as in the case of the two-component development, but the development is performed by bringing the toner layer having a thickness of several tens of μm formed on the development roll 31 into contact with the photoconductor. From the developing roll 31 and the photosensitive belt 1
Must be stably and completely contacted. Ideally, the photosensitive belt 1 and the developing roll 31 are in a contact state having a nip width. For this reason, inconvenience occurs in the developing device contact position and the guide configuration in the two-component developing device shown in FIG. FIG. 18 shows an embodiment of the configuration of the developing device contact position and the guide member of the photosensitive belt 1 when a one-component developing device is used. The photosensitive belt 1 is attached to the developing roll 31 of the developing machine for developing.
Need to be in contact with the nip. For this reason, the contact positions of the developing rolls 31 of the developing machines on both sides must be arranged inside the photosensitive member inner roller 100. As a result, the photoreceptor belt 1 bends along the developing roll 31 of the developing machine in contact therewith, and a stable nip can be easily secured. For the two central developing machines, a sufficient nip can be provided by moving the two guide rollers 413 to the developing machine side.

In addition, a guide member 40 as shown in FIG.
When 6 is used, a method of making the shape of the guide member 406 concave or a method of arranging an elastic body on the surface can be considered. Further, the developing roll itself is made of an elastic material,
A method of stably contacting the photoreceptor with the modification of 1 is also conceivable,
In a one-component developing machine having many blade friction members, the developing roll 3
In consideration of the life of the developing roller 1, it is preferable that the developing roll 31 is formed of a rigid body such as a metal body.

As described above, in the one-component developing method, since the developing devices cannot be disposed immediately above the photosensitive belts 1 at both ends, the allowable thickness of one developing device is slightly smaller than that of the two-component developing device. However, one-component development that does not require a stirring chamber, a magnet roller, and the like generally does not pose a serious problem because it can be made smaller than a two-component development system.

Next, the intermediate transfer drum 2 is configured to have a semiconductive layer or an insulating layer on the surface of the metal roller.
The surface is an elastic body of several hundred μm to several mm so as not to damage the surface of the photoconductor at the time of contact with the photoconductor belt 1.
In the color image forming apparatus shown in FIG.
By setting the base potential of the photosensitive belt 1 to about minus 500 V with respect to the ground potential, the negatively charged toner images formed on the photosensitive belt 1 are electrostatically transferred. Further, the composite image of each color image formed on the intermediate transfer drum 2 is
Is transferred onto a sheet by a transfer roller 17 disposed below the sheet. The image transfer to the sheet is performed electrostatically by applying a positive voltage to the transfer roller 17.

In order to prevent the intermediate transfer drum 2 from being charged by these processes arranged around the intermediate transfer drum 2, it is desirable that the surface insulating layer has a certain resistance or less. In the color image forming apparatus shown in FIG. 1, the process speed is 95 mm / s. The capacity of the layer on the surface of the intermediate transfer member is represented by C (F / cm ² ), and the resistance value is represented by R
(Ω / cm ² ), it takes about C × R seconds for the electric charge charged on the surface of the intermediate transfer member to escape. If this value is less than about 100 ms, the charge on the surface of the intermediate transfer drum 2 is eliminated while the intermediate transfer drum 2 moves about 1 cm. But,
If the intermediate transfer member is a conductor, a discharge or the like occurs at the time of contact with the photosensitive member or at the position of contact with the transfer roller 17, thereby causing a recorded image defect. For this reason, the surface layer of the intermediate transfer drum 2 needs to be a semiconductive material. In addition, when a charge eliminating mechanism for controlling the charging of the surface of the intermediate transfer drum 2 is arranged around the intermediate transfer drum 2, the resistance of the surface layer of the intermediate transfer drum 2 can be very high, and insulation can be achieved. As the charge removing mechanism for controlling the charging, a charge removing method in which a non-contact needle-like member is disposed, or a mechanism using discharge such as an AC corona discharger or a scorotron charger can be used.

In the color image forming apparatus according to the embodiment of the present invention shown in FIG. 1, a mechanism for transferring a color image formed on the intermediate transfer drum 2 to a sheet employs a roller transfer method. The toner image on the intermediate transfer drum 2 in which the color images of each color are combined has a different toner thickness in each part of the image. In order to transfer these images completely and reliably, it is important that the intermediate transfer drum 2 and the non-transfer medium, such as paper, are brought into close contact with each other. Therefore, in this embodiment, a roller transfer method is used. If the paper can be securely adhered to the intermediate transfer drum 2 by a paper guide or the like, corona transfer or the like can also be used.

In the color image forming apparatus according to the embodiment of the present invention shown in FIG. 1, a blade cleaning system is employed as a cleaner for the intermediate transfer drum 2.
FIG. 19 is a view showing another embodiment of the intermediate transfer drum cleaner 19 employed in the color image forming apparatus of FIG.
In the configuration of the present embodiment, since the position of the cleaner is below the side surface of the intermediate transfer drum 2, blade cleaning including the blade cleaner 473 having a simple configuration is employed. However, as described in relation to the photoconductor cleaner 13, it is desirable to apply a brush cleaning mechanism like the photoconductor cleaner 13 at a position where the cleaned toner drops toward the surface of the intermediate transfer drum 2. . The cleaner in FIG. 19 has a configuration in which a magnet roll 471 and a scraping blade 472 are disposed above to collect the carrier that has fallen from the developing roll. In the color image forming apparatus according to the embodiment of the present invention shown in FIG. 1, the waste toner and waste carrier conveyed from the photoreceptor cleaner 13 and the intermediate transfer drum cleaner 19 are conveyed by a rotating spiral in a tube. By 474, the sheet is conveyed to the waste toner box 14 in FIG.

Since the transferred paper remains on the back surface of the transferred paper, the paper adheres to the intermediate transfer drum 2 and cannot be separated by gravity alone, and the separated paper is transported to the fixing device. In the path, a discharge occurs between each component located in the surroundings, and a phenomenon that an image is disturbed occurs. Therefore, in the present embodiment, the intermediate transfer drum 2
A static elimination mechanism is provided in order to make it easy to separate from the fixing device and to prevent generation of electric discharge in the conveyance path to the fixing device. In the embodiment of the present invention shown in FIG. 1, a static elimination mechanism using AC corona discharge is used. However, a method such as brush static elimination in which a conductive brush or the like is brought into contact from the back of the sheet can also be used.

In the configuration of the color image forming apparatus according to the embodiment of the present invention shown in FIG. 1, a roller fixing device 20 is disposed below the developing device as shown in FIG. The process speed of this embodiment is 95 mm / s as described above. The outer shape and the set temperature of the fixing roller 481 are generally determined by the amount of heat supplied, the distance between the nip portions sandwiching the sheet, and the pressure thereof. In the configuration of a fixing device conventionally used in an electrophotographic printer or the like, the fixing roller 481 of the fixing device applicable at the process speed of the present embodiment has a fixing temperature of 100.
A fixing roller diameter of about 30 mm at ~ 200 ° C is appropriate.
However, these settings largely depend on the characteristics of the toner material used. Although the roller 481 of the fixing device in the color image forming apparatus having the configuration of the embodiment of the present invention shown in FIG. 1 has a diameter of about 30 mm, it can be seen that the configuration of the apparatus can be sufficiently arranged.

When the heat of the fixing device is transmitted to the toner storage unit of the developing device, a problem occurs such that the toner is melted and solidified in the developing device and the toner storage room. Because of this,
It is necessary to dispose a heat insulating member 482 such as a foamed resin plate between the fixing device, the developing device, and the toner storage chamber. Further, it is necessary to provide a heat discharging fan 483 in the sheet discharging direction and provide a mechanism for discharging heat. The present embodiment of the present invention shown in FIG. 1 has a unit configuration in which the upper and lower sides are surrounded by a heat insulating member 482 as shown in FIG.

As another method relating to the fixing machine, it is effective to apply a method using a belt-shaped conveying member and a heating element fixed at a fixing position. FIG. 21 shows an embodiment in which a fixing method using a belt-shaped conveying member 491 and a fixed heating element 492 is applied to the embodiment of the present invention shown in FIG. In this method, the amount of heat generated in the fixing device can be reduced, and the position of the heat source of the fixing device can be freely set because the heat is transferred by the belt. Further, by arranging the belt entrance of the fixing device near the transfer / peeling position of the paper, the paper transfer distance from the transfer roller 17 to the fixing device 20 can be reduced, so that recording on a small paper can be performed.

Next, the drive mechanism of the photosensitive belt 1 and the intermediate transfer drum 2 shown in FIG. 1 will be described. If the photoreceptor belt 1 and the intermediate transfer drum 2 are not completely synchronized and driven, the image positions of the respective colors cannot be accurately overlapped. Therefore, a method of controlling the rotation of both members with high accuracy using two pulse motors is conceivable. However, in order to perform such control, extremely high precision motor control and extremely high precision of the intermediate transfer drum diameter and each part of the photosensitive belt are required. Therefore, in this embodiment, FIG.
As shown in FIG. 2, the drive motor 505 is connected to the intermediate transfer drum 2.
And the photoreceptor belt 1 used a driving system that follows the belt. The rotation speed is detected by a rotation speed detection plate 501 provided on the center roller of the photosensitive belt 1 and a rotation speed detection sensor 502 for detecting the rotation speed, and is controlled to be constant. Also,
As another embodiment, as shown in FIG. 23, the roller is driven on the photoreceptor belt 1 side, and a rotation number detection plate 501 and a rotation number detection sensor 502 are installed on the intermediate transfer drum 2 side. And the intermediate transfer drum 2 is driven.

Next, a mechanism for applying tension to the photosensitive belt 1 will be described. The photoreceptor belt unit needs to be provided with a mechanism for adjusting the tension in order to absorb the belt elongation due to long-term use and the belt deflection at the time of contact with the intermediate transfer drum 2. FIG. 24 shows directions and members for applying tension to the photoconductor unit of the color image forming apparatus according to the embodiment of the present invention shown in FIG. The roller A mainly absorbs the elongation of the belt, and the rollers A and B absorb the belt deformation at the time of contact with the intermediate transfer drum. In this configuration, since the position of the roller B moves toward the intermediate transfer drum, the belt angle between the roller B and the roller C slightly changes. Therefore, in the present embodiment, the charger 11 and the photoconductor cleaner unit 13 are configured to move integrally around the fixed point D in the direction of the arrow shown in the figure. In the present embodiment, a tension applying mechanism is installed on the photoconductor inner roller C used as a guide for the laser irradiation position, since the inner roller of the photosensitive member provided with a tension applying mechanism for the photosensitive belt 1 operates. Did not.

FIG. 25 shows the open configuration of each part and the component insertion direction in the color image recording apparatus of the present invention shown in FIG. The color image forming apparatus according to the embodiment of the present invention is configured to operate with the left side in the drawing as the front. As shown in the drawing, the paper cassette 21 is configured to be inserted from the front of the apparatus. The paper is inserted and folded back from the front, and the transfer roller position 1 is disposed diagonally below the intermediate transfer drum 2.
7. The transferred sheet is discharged above the sheet cassette 21 via the fixing device 20 disposed below the developing devices 3 to 6 after being peeled off in the direction of gravity. As shown in the figure, the lid of the paper cassette 21 is configured to be able to be pulled out, and can be used as a paper tray after the paper is discharged.

Further, the toner storage chamber units 7 to 10 are also configured to be inserted from the left side in the drawing, which is the operation surface, and the photoconductor-developing unit 50 is configured to be inserted from above. Although the waste toner box 14 has a door for taking in and out on the back surface, as shown in FIG. 25, it is configured so that it falls down by opening the door, so that the taking out / in operation can be easily performed from above.

An opening for avoiding a jam is disposed below the rear surface. By making the internal transfer unit movable downward, the paper can be removed in the event of a paper jam. However, since this apparatus is small, even when the A4 paper jams, the paper cassette 21 or the fixing
It is possible to collect the jammed paper from the exit, and as described above, the fixing device 20 is unitized and configured to be pulled out from the front, so that it is possible to avoid jamming by pulling this out. is there.

In the configuration in which the paper cassettes are disposed below, it is also possible to adopt a configuration in which an additional paper cassette 21 'in addition to the main paper cassette 21 can be easily added downward as shown in FIG. .

The color image forming apparatus according to the embodiment of the present invention shown in FIG. 1 is for the purpose of A4 recording as described above.
Obviously, a color image forming apparatus capable of recording three images can be realized. However, as in the present invention, 400
A high-resolution color image forming device with a resolution of at least dpi
It is considered that there is little problem in image quality even if the image is reduced in A4 size by software processing, and printing on large paper such as A3 consumes a large amount of toner at the time of recording, and the printing area ratio is particularly high. The color image recording described in (1) requires a large amount of toner. Further, as described above, the amount of image information to be recorded is further increased to about 100 MByte or more. Considering these facts, in a small color image recording apparatus easily used on a desktop as in the present invention,
A paper size recorder of about A4 is considered appropriate. In this sense, the embodiments of the present invention mainly disclose the device size and dimensional configuration of the A4 recording machine.

FIG. 27 is a view for explaining another embodiment relating to the sheet conveyance of the present invention. Paper cassette 21
Is inserted from the right side in the figure, conveyed horizontally, and discharged to the left side. In this configuration, since the paper cassette 21 is not disposed below, it is possible to keep the height of the entire apparatus low. In the configuration of the embodiment in FIG. 27, the height of the printing apparatus main body 1000 is about 230 mm. However, in this configuration, since the color image forming apparatus needs to be operated from the left and right, there is a disadvantage that the installation space is widened as compared with the configuration of the embodiment of FIG.

FIG. 28 is a view for explaining another embodiment relating to the sheet conveyance of the present invention. The paper cassette 21 is placed vertically, and is inserted from above the printing apparatus main body 1000. The paper after recording is discharged vertically to the vertical discharge tray 560. In this configuration,
When the toner storage unit is inserted, the upper part of the paper discharge tray can be turned down. In this configuration, FIG.
In addition to achieving the same device height as the seventh embodiment, a relatively small installation space can be realized. However, since the direction in which the paper is drawn from the paper cassette is the direction of gravity, it is necessary to set the shape of the separation pad and the setting of the pressing pressure when picking the paper by the pick roller with high accuracy and to stabilize the setting.

FIG. 29 is a view for explaining another embodiment relating to the sheet conveyance of the present invention. In this apparatus, the sheet after fixing is sandwiched by the auxiliary roller 574, the sheet end face is detected by the sheet end face detection sensor 575, and the sheet passes through the return conveyance path 572 provided on the upper surface of the sheet cassette again by the conveyance direction switching claw 573. Thus, the image recording is performed via the pickup roller 15 and the registration roller 16. This enables color recording on both sides of the recording paper. This device is intended to reduce the size of the device. Therefore, a system that does not require a change in apparatus size is shown in the drawings as an embodiment. In addition to this, a method of arranging a switchback mechanism for double-sided recording inside the apparatus can be considered, but it is necessary to slightly increase the size of the apparatus.

FIG. 30 shows a configuration in which a cassette is set outside for recording only during recording without setting the paper cassette in the apparatus, and the recording paper conveyance path is inclined as shown in FIG. It is what it was. In this case, the laser exposure device 12 is arranged above the developing device and the toner cassette, and the arrangement of the intermediate transfer drum 2 is also located at the center of the photosensitive belt 1. It is necessary to provide an auxiliary roller to increase the nip. By arranging in this way,
Not only the size of the apparatus is reduced, but also the movement of the paper becomes almost linear, and the recording speed can be improved.

As described above, the photoreceptor is a belt, and the photoreceptor belt is disposed so as to be elongated in the vertical direction, and developing devices of different colors are stacked and disposed on one side surface of the photoreceptor belt 1. By placing the intermediate transfer drum on the side opposite to the side on which the machine is located, and by placing other equipment in each space, the size of the apparatus can be reduced, and the paper cassette and paper feed mechanism can be used. By arranging such that it also contributes to miniaturization,
A desktop type color laser printer can be realized.

[0095]

As described above, according to the present invention, it is possible to provide a small-sized color laser printer which is small, has high image quality and is easy to maintain, and can be easily used on a desktop.

[Brief description of the drawings]

FIG. 1 is a view showing an entire configuration of an embodiment of a color electrophotographic apparatus of the present invention.

FIG. 2 is a diagram for explaining a relationship between an outer peripheral length of an intermediate transfer member and a photosensitive belt.

FIG. 3 is a diagram for explaining a relationship between an outer peripheral length of an intermediate transfer member and a photosensitive belt.

FIG. 4 is a view for explaining dimensions of each part when the photosensitive belt is stretched by rollers.

FIG. 5 is a diagram for explaining a connection state between the toner storage chamber and the developing device main body.

FIG. 6 is a diagram illustrating a configuration of a non-magnetic one-component developing machine that can be mounted on the color image forming apparatus of FIG. 1;

FIG. 7 is a diagram for explaining the direction of gravity in the transfer unit.

FIG. 8 is a diagram illustrating details of a photoreceptor belt unit.

FIG. 9 is a diagram for explaining the details of the configuration of the charging machine.

FIG. 10 is a diagram for describing the details of a photoconductor cleaner configuration.

FIG. 11 is a diagram for explaining a configuration in which a photosensitive belt is inclined.

FIG. 12 is a diagram for explaining details of an exposure apparatus configuration.

FIG. 13 is a diagram illustrating a configuration of an optical scanning unit of the laser exposure apparatus.

FIG. 14 is a diagram for explaining an exposure unit configuration when an fθ lens is used.

FIG. 15 is a view for explaining another embodiment of the configuration of the exposure apparatus.

FIG. 16 is a diagram for explaining the detailed configuration of a developing device and a photoconductor unit.

FIG. 17 is a diagram for explaining a photoconductor guide configuration when a two-component developing machine is applied.

FIG. 18 is a view for explaining a photoconductor guide configuration when a one-component developing machine is applied.

FIG. 19 is a diagram illustrating another embodiment of the intermediate transfer drum cleaner according to the present invention.

FIG. 20 is a diagram for describing details of the configuration of a fixing device unit.

FIG. 21 is a view for explaining another embodiment of the fixing device.

FIG. 22 is a diagram illustrating a configuration of a drive system.

FIG. 23 is a diagram for explaining another configuration of the drive system.

FIG. 24 is a diagram illustrating directions and members for applying tension to the photoconductor unit of the apparatus in FIG. 1;

FIG. 25 is a diagram showing an open configuration of each unit and a component insertion direction in the apparatus of FIG. 1;

FIG. 26 is a diagram illustrating an example of adding a paper cassette.

FIG. 27 is a diagram for explaining another embodiment relating to paper conveyance.

FIG. 28 is a diagram for explaining another embodiment relating to paper conveyance.

FIG. 29 is a view for explaining another embodiment relating to paper conveyance.

FIG. 30 is a view for explaining another embodiment relating to paper conveyance.

[Explanation of symbols]

1: photoreceptor belt, 2: intermediate transfer drum, 3, 4,
5, 6 developing machine, 7, 8, 9, 10 toner storage unit, 11 charger, 12 laser exposure device, 13 photoconductor cleaner, 14 waste toner box, 15 pickup roller, 16 Registration roller, 17: transfer roller, 18: static eliminator, 19: intermediate transfer drum cleaner,
20: fixing machine, 21: paper cassette.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 G03G 15/00 554 (72) Inventor Nobuyoshi Hoshi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. 7 Hitachi, Ltd. Hitachi Research Laboratories (72) Inventor Seiji Maruo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory Hitachi, Ltd.

Claims (6)

[Claims] 1. A photoreceptor belt stretched in a longitudinal direction, and a plurality of developing devices that form a plurality of toner images of different colors on the photoreceptor belt and are stacked and disposed on one side of the photoreceptor belt. And an intermediate transfer member disposed on the other side of the photoreceptor belt to form a color toner image by sequentially superimposing the toner images formed on the photoreceptor belt. An electrophotographic device that can be taken out above the device. 2. The electrophotographic apparatus according to claim 1, further comprising a paper cassette for storing a recording medium on which the color toner image is transferred, wherein each of the plurality of developing machines and the paper cassette are attached and detached in the same direction. An electrophotographic device that is possible. 3. The electrophotographic apparatus according to claim 2, wherein the direction in which the recording medium onto which the color toner image has been transferred is discharged is the same as the direction in which each of the plurality of developing machines is removed from the apparatus. . 4. An electrophotographic apparatus according to claim 1, wherein said electrophotographic apparatus has an opening for avoiding a jam which can open an apparatus wall in a direction opposite to a direction in which each of said plurality of developing machines is taken out. . 5. The at least one electrophotographic apparatus according to claim 2, wherein said paper cassette includes a plurality of paper cassettes for storing recording media having different sizes, respectively, and said plurality of paper cassettes includes said photosensitive belt. An electrophotographic device stacked below. 6. The electrophotographic apparatus according to claim 1, wherein said intermediate transfer member has a drum shape.