JP3107627B2 - Color recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superposition transfer type color recording apparatus using a pressure transfer fixing method.

[0002]

2. Description of the Related Art Conventionally, in an image recording apparatus using an electrophotographic process, as a method for transferring a toner image formed on a photoreceptor to a transfer paper or the like, a toner charger uses a corona discharge type transfer charger to reverse the polarity of the toner. Is generally applied from the back surface of the transfer paper to transfer the toner image to the transfer paper by electrostatic attraction.

However, in this method, the toner is scattered due to a so-called transfer gap, and the toner image transferred as compared with the toner image on the photosensitive member is MT.
There is a problem that the F (modulation transfer function) is deteriorated and the contrast of the image is reduced.

As an image forming apparatus which avoids such a problem, Japanese Patent Application Laid-Open No. 62-11697 and Japanese Patent Application Laid-Open No.
As shown in FIG. 4 in Japanese Patent Application Laid-Open No. 1-65279, an intermediate transfer body cylinder 2 having an intermediate transfer body made of silicon rubber or the like wound on the surface thereof is brought into pressure contact with a photosensitive drum 1, and A pressure roller 3 is pressed against the transfer paper path, and a photosensitive drum is provided by a known electrophotographic process by an optical writing section 4, a charging charger 5, a developing device 6, and a cleaner 7 provided along the photosensitive drum 1. The toner image formed on the intermediate transfer member 2 is pressure-transferred to the intermediate transfer member cylinder 2 by an adhesive force, and the toner image transferred on the intermediate transfer member cylinder 2 is further transferred to the intermediate transfer member cylinder 2 via a paper feed roller 9 and a registration roller 11 to be subjected to intermediate transfer. An image recording apparatus 10 has been proposed in which pressure transfer and fixing is performed on transfer paper 8 that has passed through a nip portion between a body cylinder 2 and a pressure cylinder 3 and then discharged to a paper discharge tray 13 by a paper discharge roller 12. That.

By employing the above-described transfer / fixing method, it is possible to obtain a high-quality image with excellent contrast without toner scattering.

A color-separated image information signal to be developed with yellow (Y), magenta (M), cyan (C), and black (BK) from which a full-color image is obtained by superimposing by applying this method. Is sequentially written on the photosensitive drum by a laser beam carrying the toner image, and the obtained electrostatic latent image is developed with Y, M, C, and BK toners, respectively, and wound around a pressure cylinder via an intermediate transfer body cylinder. By superimposing and pressing and fixing the transferred transfer paper, a high-quality full-color image without toner scattering can be obtained.

However, in this case, since the respective color toners of Y, M, C, and BK have different rheological characteristics (flow characteristics), when the transfer and the secondary transfer and fixing are performed with the same pressing force for each color, the toner of a certain color is not obtained. Even if it is suitable for transfer and fixing, it may be unsuitable for transferring and fixing another color toner. As a result, the transfer is crushed and the quality of the color image is reduced. Therefore, it is necessary that the pressure contact force between the photosensitive drum and the intermediate transfer member cylinder and the pressure contact force between the intermediate transfer member cylinder and the pressure cylinder can be easily and independently adjusted in accordance with the flow characteristics of each color toner. .

However, the above-mentioned Japanese Patent Application Laid-Open No.
In the apparatus disclosed in No. 8, as shown in FIG. 5, the photosensitive drum 1, the intermediate transfer body cylinder 2, and the pressure cylinder 3 are arranged on one vertical line, and the intermediate transfer body cylinder 2 and the pressure The support member 14 supporting the cylinder 3 is pushed up by a spring 22 to move the intermediate transfer body cylinder 2 to the photosensitive drum 1.
, So that the spring pressure of the spring 22 is applied to the pressurizing cylinder 3 and the lever 18 as pressurizing means.
a, the spring 17a, the intermediate transfer cylinder 2, and the support member 14 must overcome the total weight of the support member 14, and the spring pressure must be very large, making it very difficult to make fine adjustments.

When the photosensitive drum 1 is replaced, the large weight of the intermediate transfer cylinder 2, the pressure cylinder 3, the pressing mechanism thereof, and the support member 14b of the intermediate transfer cylinder 2 is pushed down against the spring force. Therefore, it is necessary to separate the photosensitive drum 1 and the intermediate transfer cylinder 2 from each other, and the operation is not easy.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of an image recording apparatus of a pressure transfer and fixing system using an intermediate transfer body cylinder, which has been conventionally proposed. It is an object of the present invention to provide a color recording apparatus capable of obtaining a high-quality color image without crushing the transfer of toner images of respective colors. It is another object of the present invention to facilitate the replacement of the photosensitive drum by allowing the intermediate transfer cylinder to be easily separated from the photosensitive drum when the photosensitive drum is replaced.

[0011]

According to the present invention, there is provided an image forming apparatus comprising:
A fixing type color recording apparatus is provided with means for adjusting the pressing force between the photoreceptor drum and the intermediate transfer member cylinder and between the intermediate transfer member cylinder and the pressing cylinder. It is characterized by being adjustable independently.

[0012]

Since the color recording apparatus of the present invention is constructed as described above, Y, Y and Y are sequentially formed on the photosensitive drum.
In the pressure intermediate transfer and the pressure transfer / fixing of each color toner image of M, C, and BK, an optimum pressing force can be obtained for the flow characteristics of the toner of each color for each color and for each intermediate transfer, retransfer and fixing. The transfer force, re-transfer and fixation of each color toner can be performed satisfactorily, and a high-quality color image without transfer collapse can be obtained.

The adjustment of the pressing force may be automatically performed by sequence control.

The pressure between the photosensitive drum and the intermediate transfer cylinder and between the intermediate transfer cylinder and the pressure cylinder can be easily and independently finely adjusted independently of each other. As a configuration for easily separating the intermediate transfer body cylinder from the photosensitive drum, the photosensitive drum is rotatably supported around an axis provided at a fixed position of the apparatus main body frame, and the intermediate transfer body cylinder is The arm is rotatably supported on the upper end of an arm extending above the swing center of a pair of swing levers that are swingably supported around an axis provided at a fixed position of the apparatus body frame. The pressure cylinder is supported by a bearing slidable on a straight line connecting the swing center of the swing lever and a shaft fulcrum of the intermediate transfer body cylinder, and is provided between the pressure cylinder and the swing lever. Intermediate rotation The intermediate transfer body cylinder is brought into contact with the photosensitive drum at a position deviated from a straight line connecting the pivot of the cylinder and the swing center of the swing lever. What is necessary is just to make it press-contact to a photosensitive drum so that pressurization force can be adjusted by the pressurization means provided between the moving lever and the apparatus main body frame.

If the swing lever has a bell-crank shape, the space required is small, which is convenient for reducing the size of the apparatus.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side sectional view of a color recording apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is an enlarged view of a portion III in FIG. Note that members having the same functions as those of the conventional image recording apparatus described with reference to FIGS. 4 and 5 are denoted by the same reference numerals, and different points will be mainly described.

In the apparatus of the present embodiment, in order to obtain a full-color image by the superposition transfer method, Y, M, C, and BK toners are built in around the photosensitive drum 1 respectively.
The developing devices 6Y, 6M, 6C, 6C, and 6BK are provided. In addition, a clamper 30 for gripping the leading edge of the transfer paper is provided on the peripheral surface of the pressurizing cylinder 3 in order to superimpose and fix the four color toner images on the transfer paper 8 fed from the paper feed unit. The transfer paper 8 fed from the paper supply unit and fed at a timing by the registration roller 11 is gripped at the leading end by the clamper 30 and wound around the pressure cylinder 3 to be rotated four times. , BK are overlaid and transferred and fixed, the clamper 30 is released, and the transfer paper is discharged to the discharge tray 13 by the discharge roller 12.

The photosensitive drum 1 is pivotally supported by a face plate 31 fixed to an apparatus machine frame side plate 32, and the intermediate transfer member cylinder 2 is provided outside a side plate 32 of the apparatus machine frame with a shaft 33 pivotally supported between the side plates.
The pressure cylinder 3 is supported at the upper end of an arm that rises vertically above the shaft 33 of the pair of swing levers 34 fixed to both ends of the pressure cylinder 3.
Are elongated holes formed in the arm of the swing lever along a straight line connecting the axis of the intermediate transfer body cylinder 2 and the axis of the swing shaft 33 of the swing lever. It is supported by a slide bearing 35 slidably provided in the inside.

The swing lever 34 has a bell-crank shape bent at the shaft fulcrum 33, and has a point near the free end of the horizontal arm;
A pressure spring 37 stretched between the eccentric point on the pressure adjustment eccentric cam 36 rotatably provided on the machine frame below the device frame is urged in a counterclockwise direction. Since the axis of the photosensitive drum is disposed on the left side in the figure from the straight line connecting the axis of the intermediate transfer cylinder 2 and the axis of the pressure cylinder 3, the swing lever 36 by the pressure spring 37 is moved. Due to the urging force urging in the counterclockwise direction, the intermediate transfer body cylinder 2 is pressed against the photosensitive drum 1 on the left side of a vertical line passing through the axis thereof. When the photosensitive drum 1 is replaced, as a means for separating the intermediate transfer body cylinder 2 from the photosensitive drum 1 and holding the intermediate transfer cylinder 2 at that position, a cam surface is opposed to the lower surface near the tip of the horizontal arm of the swing lever 34 and an eccentric cam 38 is provided. Is provided. Eccentric cam 3
8 is rotated by a motor 45 to rotate the swing lever 34 clockwise to separate the intermediate transfer body cylinder 2 from the photosensitive drum 1, and then remove the face plate 31 from the machine frame side plate 32, thereby The drum 1 can be easily replaced.

As means for pressing the pressure cylinder 3 against the intermediate transfer cylinder 2, the swing center 33 of the swing lever 34 is used.
A swing center 39 provided at a portion projecting further obliquely downward and to the right.
A pressure lever 40 that can swing around is provided.
The pressure lever 40 also has a bell-crank shape, and the upper edge of one arm abuts on the lower side of the bearing 35 of the pressure cylinder 3, and is rotatably provided near the free end of the other arm and on the swing lever 34. A pressurizing spring 42 is stretched between the pressurizing adjustment eccentric cam 41 and the eccentric point on the pressurizing adjustment eccentric cam 41, and urges the pressurizing lever 40 to rotate clockwise. It is pressed against the body cylinder 2.

Each member for pressing the pressure cylinder 3 against the intermediate transfer body cylinder 2, the pressure cylinder 3 and the intermediate transfer body cylinder 2 are all provided on the swing lever 34. The pressing force of the pressure cylinder 3 against the transfer cylinder 2 and the pressing force of the intermediate transfer cylinder 2 against the photosensitive drum 1 are independent of each other by adjusting the rotational positions of the respective pressure adjusting eccentric cams 41 and 36. Can be adjusted. Intermediate transfer body cylinder 2, pressure cylinder 3, swing lever 34 that supports these
Since the entire weight of the pressure lever 40 and the pressure spring 42 for applying the pressing force between the pressure cylinder 3 and the intermediate transfer body cylinder 2 is supported by the shaft 33, the spring force of the pressure spring 37 is small. Fine adjustment of the pressing force by the pressure adjusting eccentric cam 36 and separation of the intermediate transfer cylinder 2 from the photosensitive drum 1 by the eccentric cam 38 become easy. The swing lever 34 and the pressure lever 40 may not have a bell-crank shape, but may have a shape in which the arm on which the pressure spring is attached is extended below the fulcrums 33 and 39. There is a difficulty in increasing the size. Therefore,
It is desirable that the swing lever 34 and the pressure lever 40 have a bell crank shape.

The press-contact forces between the photosensitive drum and the intermediate transfer cylinder 2 and between the intermediate transfer cylinder and the pressurizing cylinder 3 are the best, respectively, and for each color toner according to the flow characteristics of each color toner. The pressing force is adjusted to obtain an intermediate transfer and re-transfer and fixation. This adjustment is performed by automatically rotating the cam motors 43 and 44 for driving the pressure adjusting eccentric cams 36 and 41 to predetermined positions for each color by a sequence control unit (not shown) so as to automatically obtain an optimal pressing force. Is done.

[0024]

As described above, according to the present invention, in a color recording apparatus in which a full-color image is obtained by superimposing and transferring toner images of respective colors by using a pressure transfer fixing method, each color toner is transferred and fixed for each transfer. Since an optimal pressing force according to the flow characteristics of the toner can be obtained, a high-quality color image free from toner image transfer collapse can be automatically obtained. Further, replacement of the photosensitive drum is facilitated.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a color recording apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged sectional view of a part III in FIG. 2;

FIG. 4 is a side sectional view of an example of a conventional image recording apparatus of a pressure transfer / fixing method using an intermediate transfer body cylinder.

FIG. 5 is a side view showing the pressing mechanism.

[Explanation of symbols]

Reference Signs List 1 photosensitive drum 2 intermediate transfer cylinder 3 pressure cylinder 4 optical writing unit 6Y, 6M, 6C, 6BK Y, M, C, BK developing device 8 transfer paper 32 device body frame side plate 33 rocking of rocking lever Center of movement 34 Swing lever 35 Sliding bearing 36 Pressure adjustment eccentric cam 37 Pressure spring 38 Eccentric cam (for maintaining separation between the photosensitive member and the intermediate transfer paper cylinder) 40 Pressure lever 41 Pressure adjustment eccentric cam 42 Addition Compression spring 43, 44, 45 Motor

Continuation of the front page (56) References JP-A-59-81667 (JP, A) JP-A-61-65279 (JP, A) JP-A-62-52574 (JP, A) JP-A-62-116978 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 15/01 114

Claims (4)

(57) [Claims] A photoreceptor drum, an intermediate transfer body cylinder formed by winding an intermediate transfer body which is pressed against the photoreceptor drum, and temporarily transfers a toner image formed thereon to a surface thereof;
A pressurizing cylinder for rotating a transfer paper on which the toner image pressure-transferred to the intermediate transfer body cylinder is pressure-transferred and fixed by pressing the intermediate transfer cylinder, and carrying a color separation image information signal The latent images sequentially formed by exposing the photosensitive drum on the photosensitive drum with incident light are developed with yellow, magenta, cyan, and black toners, respectively, and each color toner image obtained is transferred to the transfer paper via the intermediate transfer cylinder. In an electrophotographic color recording apparatus that obtains a color image by superimposing and transferring a color image, a means for adjusting a pressing force between a photosensitive drum and an intermediate transfer body cylinder, Means for adjusting the pressing force between the pressing cylinder and the pressure cylinder, and the pressing forces can be adjusted independently of each other. 2. The apparatus according to claim 1, wherein the photosensitive drum is rotatably supported around an axis provided at a fixed position of the apparatus body frame.
The above-mentioned intermediate transfer body cylinder is rotatable at the upper end of an arm extending above the swing center of a pair of swing levers which are swingably supported around an axis provided at a fixed position of the apparatus body frame. The pressure cylinder is pivotally supported by a bearing slidable on a straight line connecting the pivot center of the pivot lever and the pivot point of the intermediate transfer body cylinder. The intermediate transfer body cylinder is pressed against the intermediate transfer body cylinder by a pressurizing means provided between the lever and the intermediate transfer body cylinder so that the pressing force can be adjusted, and the intermediate transfer body cylinder is moved from a straight line connecting the pivot of the cylinder and the swing center of the swing lever. It comes into contact with the photoconductor drum at a deviated position, and is pressed against the photoconductor drum so as to be capable of adjusting the pressing force by a pressurizing means provided between the swing lever and the apparatus body frame. The color recording apparatus according to claim 1. 3. The color recording apparatus according to claim 2, wherein said swing lever has a bell crank shape. 4. When the toner images of the respective colors are sequentially transferred from the photosensitive drum to the intermediate transfer body cylinder and from the intermediate transfer body cylinder to the transfer paper, the photosensitive body and the intermediate transfer are transferred in accordance with the flow characteristics of the respective color toners. 3. The color recording apparatus according to claim 1, further comprising control means for automatically adjusting the pressure between the body cylinders and between the intermediate transfer body cylinder and the pressure cylinder.