JP2765360B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile, etc., and more particularly to a pressure transfer roll for transferring a toner image carried on a toner image carrying drum onto a transfer material. Alternatively, the present invention relates to an improvement in an image forming apparatus of a type which performs pressure transfer fixing.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, for example, Japanese Patent Publication No. 57-501348 or Japanese Patent Publication No.
There is one disclosed in 00831. This is because a hollow transfer fixing roll is disposed adjacent to a hollow dielectric drum, and a load is applied from both ends of the dielectric drum and the transfer fixing roll to a recording paper inserted between the dielectric drum and the transfer fixing roll. Is applied to apply pressure to transfer and fix the toner image formed on the dielectric drum on the recording paper.

[0003]

[Problems to be Solved by the Invention] By the way, Japanese Patent Publication No.
In the pressure transfer fixing device disclosed in JP-A-501348 or JP-A-60-500831, a load is applied to both ends of a hollow dielectric drum and a hollow transfer fixing roll to apply a pressure between the dielectric drum and the transfer fixing roll. Is occurring. In this case, the dielectric drum and the transfer fixing roll 2
If the rolls are arranged in parallel, the transfer rate is poor.
The rolls of the book are arranged crossing each other to cause a slight slip between the dielectric drum and the recording paper to improve the transfer rate.

By the way, in a type in which pressure is applied to two rolls by the above-described method to perform transfer and fixing,
If the intersection angle between the two is small, a large pressure is applied only to both ends, and the pressure at the center becomes small, so that the transferability and the fixability at the center are worse than those at both ends. Therefore, special table Sho 60-
As shown in 500831, the crossing angle is set to 0.5 ° or more. However, if the crossing angle is increased, when the recording paper passes between the dielectric drum and the transfer fixing roll, as shown in FIG. As described above, the recording paper 17 is inevitably skewed, so that the so-called oblique printing in which the printed arrangement of the transferred image G is oblique becomes a major technical problem. For example, when the crossing angle θ is 0.7 °, when vertical printing is performed on A4 size recording paper, the vertical lines at the upper and lower ends are δ = 3.63 m.
m also shifts. This is particularly noticeable when printing a chart that uses a lot of straight lines or a document with a small margin at the edges. Furthermore, the skew of the recording paper causes a technical problem that the recording paper is easily damaged due to shear force acting on the recording paper, such as wrinkling of the recording paper. Problem.

In order to avoid this, the diameters or thicknesses of the dielectric drum and the transfer fixing roll are increased to increase the rigidity of the two rolls, thereby suppressing the deflection of each roll.
Along with this, it is necessary to reduce the crossing angle of each roll body to make it closer to parallel, but increasing the rigidity of the two roll bodies results in an increase in the weight and size of the device itself, This is not the preferred solution.

In particular, when the two rolls are lengthened to obtain the same pressure, it is necessary to increase the acting load. However, when the acting load is increased, the transfer fixing roll is required. As the amount of deflection increases, it is necessary to increase the crossing angle between the dielectric drum and the pressure fixing roll in order to obtain a uniform pressure between the dielectric drum and the transfer fixing roll. Therefore, when the length of the dielectric drum and the transfer fixing roll is increased, the above-described technical problems are more remarkable.

In order to solve such a technical problem,
For example, it is conceivable to apply the technology described in Japanese Patent Application Laid-Open No. 49-77641. This is a technique related to a pressure roll fixing device, which supports one of two rigid rolls arranged in parallel in the axial center, and sets the second moment of area of the two rolls equal. In this way, the pressure acting between the two rolls is intended to be uniform.

[0008] However, even if such a technique is applied, the deflection curves of the dielectric drum and the transfer / fixing roll are changed due to the fundamentally different configuration of the two rolls of the dielectric drum and the transfer / fixing roll. It is extremely difficult to obtain a uniform pressure distribution between the two and it is extremely difficult to obtain a uniform pressure distribution between them. For example, as shown in Japanese Patent Application Laid-Open No. 3-150585, the deflection curves of the dielectric drum and the transfer fixing roll are completely adjusted. Therefore, there is a technical problem in that the configuration of the apparatus becomes complicated, for example, by processing the surface shape of one roll body in consideration of the degree of bending deformation.

As another solution, the pixel writing timing of the electrostatic latent image writing head is appropriately shifted by, for example, a software measure, or the electrostatic latent image writing head itself is moved with respect to the axis of the dielectric drum. Although it is conceivable to place the head diagonally, it is more costly than necessary in the case of software measures. At an angle of 2 °, the total length of the dielectric drum is 320
If the outer diameter is 100 mm, the difference between the distance between the electrostatic latent image writing head and the surface of the dielectric drum between the center and the end of the electrostatic latent image writing head is as large as about 300 μm. This greatly exceeds the allowable value for maintaining the normal image quality.

Such a technical problem similarly arises between a toner image carrier such as a dielectric drum and a transfer roll on which only transfer is performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problems, and it is an object of the present invention to increase the rigidity of a toner image carrying drum and a pressure transfer roll while effectively avoiding complication of the apparatus configuration. Another object of the present invention is to provide an image forming apparatus capable of effectively preventing oblique printing due to skew of a transfer material and damage to the transfer material and minimizing wear of a toner image carrying drum. Further, the present invention provides an image forming apparatus capable of solving the above technical problem without increasing the crossing angle and rigidity of the two rolls even when the toner image carrying drum and the pressure transfer roll are made longer. Is what you do.

[0012]

That is, the present invention provides:
As shown in FIG. 1, a toner image carrying drum 1 on which a toner image is carried, and a transfer material 2 which is arranged adjacent to the toner image carrying drum 1 and is pressed against the toner image carrying drum 1 to form a toner image Transfer material 2 from toner image on carrier drum 1
Pressure transfer roll 3 for pressure transfer or pressure transfer fixation to
In the image forming apparatus, one of the toner image bearing drum 1 and the pressure transfer roll 3 is supported by both end support portions 4 and 5 in the axial direction, and the other is supported by the central support portion in the axial direction. 6 and furthermore, both axes O1,
O2 crossed at a small angle θ in the range of 0 ° <θ <0.5 °
It is characterized by being placed .

In such a technical means, the toner image bearing drum 1 may be a dielectric drum on which a latent image can be written by an ion beam, or a light beam (a reflection of a document irradiated with light). Light, laser beam, LE
D, a fluorescent display tube, or a photosensitive drum on which a latent image can be written by an irradiation beam from an optical recording head such as an EL (electric luminescence element). More specifically, the dielectric drum is not limited to, for example, the one in which an aluminum substrate surface is anodized, but one in which a dielectric layer is formed on the surface of a conductive substrate and the surface is pressurized. Any material having sufficient strength to withstand the pressure required for transfer (including pressure transfer fixing) may be used. As an example, a substrate obtained by depositing an inorganic film such as silicon nitride or silicon carbide on a surface of an aluminum substrate by a method such as plasma CVD. Also, as for the photosensitive drum, for example, since the surface of the photosensitive drum using amorphous silicon as the photosensitive layer has strength enough to withstand high pressure, it is possible to apply pressure by directly pressing the pressure transfer roll 3. That is, since the pressure transfer step similar to that of the dielectric drum can be performed, it is included in the application of the present invention.

The pressure transfer roll 3 may be a roll for transferring and fixing the toner image on the toner image bearing drum 1 to the transfer material 2, or a toner image on the toner image bearing drum 1. The fixing device such as a fuser roll may be separately required as post-processing just by transferring the toner image to the transfer material 2.

Further, the support structure of the toner image bearing drum 1 and the pressure transfer roll 3 may be appropriately changed as long as one of them is supported at the axial center portion 6. In this case, the support range of the central portion can be appropriately selected as long as it is a range that can withstand a required load and a range that the support target can surely support without rattling. 10-1 / 2
It may be in the range of about 1/6, and more preferably in the range of 1/6 to 1/3.

Further, the other support structure of the toner image carrying drum 1 and the pressure transfer roll 3 may be appropriately selected as long as it is supported at least at both ends 4 and 5 in the axial direction. Any solid may be used, but from the viewpoint of weight reduction, a hollow shape is preferable.

The intersection angle θ between the toner image carrying drum 1 and the pressure transfer roll 3 may be appropriately selected according to the allowable range of image distortion on the transfer material 2. That is,
The transfer rate of the toner increases as the amount of slip between the toner image bearing drum 1 and the transfer material 2 increases, that is, as the intersection angle between the toner image bearing drum 1 and the pressure transfer roll 3 increases.
Approach. However, as the intersection angle increases, the image distortion increases, and paper wrinkles and the like tend to occur. Therefore, the intersection angle θ between the toner image carrying drum 1 and the pressure transfer roll 3 of the image forming apparatus according to the present invention is 0.
It is desirable that the range of ° <θ <0.5 ° is satisfied.

Further, from the viewpoint of making the working pressure between the toner image bearing drum 1 and the pressure transfer roll 3 more uniform, the toner image bearing drum 1 side, the pressure transfer roll 3 side, or It is preferable to provide an elastic layer on both. In this case, the material and thickness of the elastic layer may be appropriately selected as long as a sufficient transfer nip pressure can be obtained for the transfer material 2.

[0019]

According to the above-mentioned technical means, one between the toner image bearing drum and the pressure transfer roll is supported at both axial ends, and the other is supported at the axial center. Therefore, the toner image carrying drum 1 and the pressure transfer roll 3
The degree of flexural deformation of the surface portion of FIG. Further, since the toner image carrying drum 1 and the pressure transfer roll 3 are arranged in an intersecting manner, the transfer ratio to the transfer material 2 is improved by a slight slip acting between the toner image carrying drum 1 and the pressure transfer roll 3. I do. At this time, since the intersection angle θ between the toner image carrying drum 1 and the pressure transfer roll 3 is very small in a range where image distortion on the transfer material 2 is allowed, oblique printing and damage to the transfer material may be performed. In addition to recording an extremely small number of images, the wear between the toner image bearing drum 1 and the surface of the toner image bearing drum 1 is reduced as much as the slip between the toner image bearing drum 1 and the transfer material 2 is suppressed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. Embodiment 1 FIGS. 2 and 3 are explanatory views showing a schematic configuration of Embodiment 1 of an image forming apparatus to which the present invention is applied. In the figure,
The image forming apparatus according to this embodiment includes an electrostatic latent image writing head 11, a developing unit 12, a developing unit 12, and an image forming process, around a dielectric drum 10 in which a dielectric layer 10b is formed on a surface of a conductive substrate 10a. Transfer fixing roll 13, cleaner 1
4 and a static eliminator 15 are provided. The electrostatic latent image writing head 11 is disposed along the axial direction of the dielectric drum 10 while maintaining a constant gap between the electrostatic latent image writing head 11 and each of the pixels arranged along the axial direction. The on / off control of the ion irradiation output is performed independently. Further, a pressure fixing toner is formed in a thin layer on the developing roll 121 of the developing device 12. Further, the transfer fixing roll 13
Is pressed into contact with the dielectric drum 10 by pressurizing means (not shown), and a metal blade 141 is provided in the cleaner 14 so as to be in contact with the dielectric drum 10 at a predetermined angle. Have been. The static eliminator 15
Is composed of, for example, a normal corona discharger.

The image forming method of the image forming apparatus according to this embodiment is as follows. That is, the electrostatic latent image writing head 11 applies a charge corresponding to the image information to the dielectric drum 10 to form an electrostatic latent image. Next, the formed electrostatic latent image is developed with a toner by a developing device 12 to be visualized, and the toner image 1 is formed on a dielectric drum 10.
6a is formed. The toner image 16a is
The image is transferred and fixed by pressure on the recording paper 17 supplied between the transfer fixing roll 20 and the fixing image 16.
b is obtained. After the transfer and fixing, the toner 16c remaining on the dielectric drum 10 is mechanically scraped off by the metal blade 141. Further, the electric potential on the surface of the dielectric drum 10 is made uniform by the static eliminator 15, and one cycle is completed.

Next, the dielectric drum 10 and the transfer fixing roll 13 used in this embodiment will be described.
First, the dielectric drum 10 is, for example, as shown in FIG.
The surface of a cylindrical drum body 101 made of aluminum is anodized to form a dielectric layer 102 having a thickness of 35 μm. Both ends of the drum body 101 are closed with cap members 103. 10
A shaft member 104 for supporting rotation is integrally provided on the outside of the shaft 3, and the shaft members 104 on both sides are rotatably supported by bearings 105. Incidentally, the total length L in the axial direction of the dielectric drum 10 according to this embodiment is 230 m.
m, the outer diameter is 100 mm, and the thickness t1 is 17 mm.

Next, as shown in FIG. 3, the transfer / fixing roll 13 has a cylindrical roll main body 131 made of iron, a center support member 132 fitted and mounted at the center of the roll main body 131, and a center support member 132. A shaft member 133 for rotation support, which is integrally formed at both ends of the member 132, is provided.
At 34, the bearing is rotated. The surface of the roll body 131 is covered with an elastic layer 135 made of, for example, polyacetal resin. The overall length L in the axial direction of the transfer fixing roll 13 according to this embodiment is 230 mm, its outer diameter is 72 mm, and the thickness of the roll body 131 is 5.5 m.
m, the thickness of the elastic layer 135 is 6 mm.

In the dielectric drum 10 and the transfer / fixing roll 13 having such a configuration, the pressure distribution when the transfer / fixing roller 13 and the dielectric drum 10 are brought into pressure contact with each other so that their respective axes are parallel to each other. Is shown in FIG. In the figure, by changing the length dimension M of the center support member 132 by, for example, 20, 40, 60 (mm),
The pressure can be increased at the center or at the end, but it is understood that a substantially uniform pressure can be obtained in each case.

Further, in this embodiment, the toner image developed on the dielectric
In order to transfer the image on the recording medium, the dielectric drum 10 and the transfer fixing roll 13 are slightly crossed by θ (0.4 ° in this embodiment) as shown in FIG.
7 has a small slip. That is,
Since the recording paper 17 follows the transfer fixing roll 13 because the surface of the dielectric drum 10 is a mirror surface, a small slip occurs between the recording paper 17 and the dielectric drum 10 (see FIG. 6).

Since the pressure distribution between the two rolls becomes slightly higher at the center due to the intersection, the center support member 132 exerts a pressure when the two rolls are pressed in parallel. A length that is slightly higher at the end may be selected in advance. In this embodiment, the length of the center support member 132 is set to about 60 mm. In this way, by appropriately selecting the optimal length of the center support member 132 according to the length, diameter, wall thickness, intersection angle, and the like of the rolls, it is possible to always obtain a uniform pressure distribution between the rolls. You can.

In the image forming apparatus according to this embodiment, a total load of 700 kgf (350 kgf on one side) is applied to the end of the shaft member 133 of the transfer and fixing roll 13 so that the gap between the dielectric drum 10 and the transfer and fixing roll 13 is increased. When pressure was generated to perform transfer fixing, the transfer was performed at a better transfer rate than when the dielectric drum 10 and the transfer fixing roll 13 did not intersect at all, and the fixability was also good. confirmed.

Further, in this embodiment, the intersection angle θ between the dielectric drum 10 and the transfer fixing roll 13 is set to 0.1.
Although it is set to 4 °, the crossing angle θ of each roll body is related only to the amount of slip, and it is sufficient that the crossing angle θ has a minimum angle at which the transfer is sufficiently performed. Further, since the amount of the slip is constant with respect to the intersection angle θ regardless of the length of the roll body, it is not necessary to increase the intersection angle θ itself even if the roll body becomes longer. On the other hand, when the dielectric drum 10 and the transfer fixing roll 13 are both solid or hollow and supported at both ends, the intersection angle between the two is deeply related to the uniformity of the pressure distribution. Alternatively, the size of the roller is increased, and this tendency is particularly remarkable when the roll body is elongated.

Embodiment 2 In this embodiment, a case where the present invention is applied to a system which is longer than in Embodiment 1 will be described. In this embodiment, the dielectric drum 10 and the transfer fixing roll 1
The diameter, material, basic configuration of the system, and image recording method are the same as those in the first embodiment, but the total length of the dielectric drum 10 and the transfer fixing roll 13 is 320 mm. still,
Electrostatic latent image writing head 11, developing machine 12, cleaner 1
4. The static eliminator 15 is also elongated according to the dielectric drum 10 and the transfer fixing roll 13.

FIG. 7 shows the axial distribution of the pressure generated between the two rolls in a comparative example in which a hollow roller (made of iron) supported at both ends is used as the transfer fixing roll 13. Show. According to FIG. 7, from the viewpoint of the uniformity of the pressure distribution, it is understood that the intersection angle θ between the dielectric drum 10 and the transfer fixing roll needs to be an angle close to 2 °. It has been confirmed that the degree is fatal and the occurrence rate of paper wrinkles and the like is extremely high.

For this reason, in this embodiment, as the transfer fixing roll 13 of such a long system, only the center portion in the axial direction of the roll main body 131 is supported by the center support member 132 as in the first embodiment. Was used. That is, parameters other than the entire length of the transfer fixing roll 13, that is, the outer diameter, the thickness, the material, the configuration, and the like of the dielectric drum 10 and the transfer fixing roll 13 are all the same as those in the first embodiment. Further, in this embodiment, a sensor support member 132 having a length of 75 mm is used as the transfer fixing roller 13.
The intersection angle with the dielectric drum 10 was set to 0.4 °.

In this embodiment, the steps of forming an electrostatic latent image, developing, transferring and fixing, cleaning, and removing static electricity were sequentially performed in the same image forming process as in the first embodiment.
The obtained image was good in both transfer rate and fixability.

Further, when the uniformity of the pressure between the rolls of such an image forming apparatus was quantitatively examined, the following results were obtained. First, when the transfer fixing roll 13 is arranged in parallel with the dielectric drum 10 and a load is applied to both ends of the two rolls, the axial distribution of the pressure generated between the two rolls is shown. FIG. Note that FIG. 3 shows the results of changing the length of the center support member M to 90, 75, and 60 mm. According to the figure, it is confirmed that a substantially uniform pressure is obtained between the rolls even when the rolls are elongated. Then, the transfer and fixing roll 13 is moved relative to the dielectric drum 10 by θ = 0.
When crossed by 4 °, as shown by the solid line in FIG.
It was confirmed that the uniformity of the pressure between the roll bodies was maintained. In FIG. 9, the dotted line shows an uneven pressure distribution even though the hollow transfer fixing rolls of the same weight condition are arranged to cross the dielectric drum 10 by θ = 0.4 °.

Further, in this embodiment (the same applies to the first embodiment), the surface of the transfer fixing roll 13 is covered with an elastic layer 135. As shown by a solid line in FIG. Type without layer 135 (shown by dotted line in the figure)
It can be understood that the uniformity of the pressure distribution between the two roll bodies is further improved as compared with the case of FIG. That is, the elastic layer 13
5 is capable of absorbing a bending deformation degree error of the surface portions of the dielectric drum 10 and the transfer fixing roll 13, so that the bending deformation degrees of both surface portions become equivalent to a state in which they are completely matched. Is considered to be kept more uniform.

Example 3 This example has basically the same configuration as Examples 1 and 2, and the weight of the dielectric drum 10 and the transfer fixing roll 13 is 6.0 and 7.7 kg. The intersection angle θ between the two is 0.4 °, the length of each roll body is 380 mm, and the load applied to each roll body is 1156 g. The images obtained by this embodiment are the same as those in the first embodiment.
As in the case of No. 2, both the transfer rate and the fixability were good.
At this time, Comparative Example 1 (both ends supporting both the dielectric drum and the transfer and fixing roll) having the same weight conditions as in Example 3 and Comparative Example 2 (Dielectric Drum,
When the conditions for obtaining the same transfer rate and fixing property as in Example 3 were examined in the case of both ends supporting both the transfer and fixing rolls, the comparative example 1 requires that the intersection angle θ be 1.3 °. Rather, the problem of oblique printing becomes remarkable,
In Comparative Example 2, both weights were 20.0, 10.0
It was confirmed that Kg had to be used, which did not meet the demand for downsizing of the device.

In the first and second embodiments, the structure for supporting the transfer fixing roller 13 at the center is provided. However, the present invention is not limited to this, and as shown in FIG. The same effect can be obtained even if the above-described structure is provided on the drum 10 side.

[0037]

As described above, according to the present invention, by improving the support structure of the toner image carrying drum and the pressure transfer roll, and the positional relationship between the two, the transfer angle between the two can be reduced. In this state, the uniformity of the pressure between the two can be maintained satisfactorily, so that the toner image carrying drum and the pressure transfer can be effectively avoided while effectively complicating the device configuration. Without increasing the rigidity of the roll, the oblique printing of the transfer material and the damage to the transfer material can be effectively prevented, and the wear of the toner image carrying drum can be minimized.
In particular, in the present invention, even if the roll body is long,
Since there is no need to increase the crossing angle and rigidity of the rolls, it is possible to provide a small and long-life image forming apparatus in which oblique printing is effectively prevented regardless of the length of the rolls.

[Brief description of the drawings]

FIG. 1A is an explanatory diagram showing a configuration of an image forming apparatus according to the present invention, and FIG. 1B is a view seen from an arrow A in FIG.

FIG. 2 is an explanatory diagram showing Embodiment 1 of the image forming apparatus to which the present invention is applied.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a graph illustrating a change in pressure distribution due to a change in the length of the center support member of the transfer and fixing roll according to the first embodiment.

FIG. 5 is an explanatory diagram illustrating an arrangement relationship between a dielectric drum and a transfer fixing roll according to the first embodiment.

FIG. 6 is an explanatory diagram showing a state of transfer operation to recording paper based on the arrangement relationship of FIG. 5;

FIG. 7 is an explanatory diagram showing a pressure distribution between a dielectric drum and a transfer fixing roll in a comparative example.

FIG. 8 is a graph showing a change in pressure distribution due to a change in the length of the center support member of the transfer / fixing roll according to the second embodiment.

FIG. 9 is a graph showing a pressure distribution between a dielectric drum and a transfer fixing roll according to Example 2.

FIG. 10 is a graph showing a change in pressure distribution between a dielectric drum and a transfer fixing roll based on the presence or absence of an elastic layer of the transfer fixing roll in Example 2.

FIG. 11 is an explanatory diagram showing a modification of the image forming apparatus to which the present invention is applied.

FIG. 12 is an explanatory diagram showing a defect of a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Toner image carrying drum, 2 ... Transfer material, 3 ... Press transfer roll, 4, 5 ... Both ends support part, 6 ... Central support part, (theta) ... Cross angle, O1: Toner image carrying drum axis, O2 ... Addition Axis of pressure transfer roll

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuo Asano 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. In-house (72) Inventor Tetsuro Kodera 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. Ebina Works (56) References JP-A-61-135761 (JP, A) JP-A-61-198180 (JP, A) Japanese Utility Model Showa 58-154962 (JP, U) Japanese Utility Model Hei 1-177766 (JP, U) Japanese Utility Model Showa 57-93964 (JP, U) Japanese Patent Publication No. 54-35496 (JP, B2) (58) (Int.Cl. ⁶ , DB name) G03G 15/16 G03G 15/20

Claims (1)

(57) [Claims] 1. A toner image carrying drum (1) on which a toner image is carried, and a transfer material (2) which is disposed adjacent to the toner image carrying drum (1) and is inserted, is located on the toner image carrying drum (1) side. A pressure transfer roll (3) for pressure-transferring or fixing the toner image on the toner image bearing drum (1) onto the transfer material (2) by being pressed against the toner image bearing drum (1). Either (1) or the pressure transfer roll (3) is supported at both ends in the axial direction (4, 4).
5), the other end is supported by a central support portion (6) in the axial direction, and both axes (O1, O2)
At a small angle (θ) in the range of 0 ° <θ <0.5 °
An image forming apparatus characterized in that location.