JPS62138874A - Developing device - Google Patents

Abstract

PURPOSE:To compensate difference in or deformation of the configuration of a toner carrier or latent image carrier and to secure proper development nip width by pressing a support member which supports a toner carrier against a latent image carrier and also pressing the toner carrier itself against the latent image carrier by a pressure member. CONSTITUTION:At least either of a developing roller 5 and a photosensitive body 7 is so constituted preferably that the surface part deforms elastically in order to obtain proper nip width W. The developing roller 5 consists of a roller shaft 5a made of conductive metal, etc., and an elastic material layer 5b outside it which is made of rubber, etc.; and it is considered that the surface part of the developing roller 5 has elasticity and the photosensitive body 7 has an rigid surface. Further, the developing roller (toner carrier) 5 is supported rotatably on the side wall of a toner container 1, and a hook part 1d projected from the support member (toner container) 1 is engaged with a support pin 8 fixed to the machine frame of an image forming device, so that the whole unit type developing device is supported so that it swing as shown by an arrow A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for press-contacting a thin-layered I~lunar carrier to a replacement image carrier through the thin layer. The static and Tt latency of the latent image carrier can be controlled 1lIlll 1
131 image device.

The above-mentioned type of developing device used in electronic copying machines, printers, facsimile machines, etc. is well known. In this type of developing device, a henna carrier and a latent image carrier are brought into pressure contact with each other via a thin toner WJ to produce a predetermined image.
Elephant nip width must be maintained. The developing nip width is the contact width between the henna 1 carrier and the latent image carrier in the direction of movement or rotation of the latent image carrier, and if this nip width is too small, the density of the developed visible image will be low. On the other hand, if it is too large, the toner adhering to the latent image carrier may be rubbed off by the toner carrier, resulting in density unevenness in the visible image. For this reason, in the past, when adjusting the position of a pair of toner carrier and latent image carrier (=1), they were brought into pressure contact while moving them relatively, and when a predetermined developing nip width was obtained, the relative position of the two was adjusted. However, with this method, it is not only difficult to assemble the toner carrier and the latent image carrier to obtain an appropriate nip width.

Due to slight irregularities on the surface of the toner carrier or ef & carrier, manufacturing errors, etc., these shapes MA
Even a slight deviation from the ideal shape may impede uniform contact between the two, and there is a risk that an appropriate developing nip width may not be obtained. Therefore, the support member that supports the toner carrier (usually a toner container containing toner) is pressed against the latent image carrier by a pressing means such as a spring.
- A structure has been proposed in which the toner carrier is elastically pressed against the latent image carrier. However, even with this configuration, slight irregularities or eccentricity on the surface of the I~lunar carrier or the latent image carrier prevent uniform pressure contact between the two, resulting in uneven development nip width or periodic The rfl
There was a risk that density unevenness and white spots would occur in the fiJl visible image.

It is an object of the present invention to solve the problem of the conventional method described at the beginning, which eliminates the above-mentioned drawbacks of the conventional technology through a simple construction. The purpose is to provide equipment.

In order to achieve the above object, the present invention presses a support member supporting a toner carrier against the latent image carrier, and also presses the toner carrier itself against the latent image carrier by a pressing member. Suggest a configuration.

An embodiment of the present invention will be described below with reference to the drawings.

In addition, the above-mentioned drawbacks of the conventional technology will be clarified with reference to the drawings.

FIG. 1 shows an example of a developing device according to the present invention, in which a toner container 1 contains toner (-component developer) 2. As shown in FIG. The toner 2 is a powder containing only toner particles or auxiliary components, and may be a magnetic toner or a non-magnetic toner. Toner 2 in toner container 1
is brought close to the 1-toner replenishing roller 4 by an agitator 3 that is rotationally driven, and is conveyed by the rotation of the roller 4 toward a toner carrier configured as a developing roller 5 that is rotationally driven in a counterclockwise direction. Let it go.

The replenishment roller 4 shown as an example in the figure has an outer layer 4a.
is made of foam or an elastic body such as sponge, for example, Pridistone polyurethane foam (trade name: Everlite TS).

Efl, the toner sent to the image roller 5 is sent to the J brother image roller 5.
The toner is triboelectrically charged by contacting the surface of the toner, and is made into a thin layer by a blade-shaped toner thickness regulating member 6 pressed against the developing roller 5 . At this time, the toner is subjected to a frictional action between the regulating member 6 and the developing roller 5, and is even more strongly frictionally charged. 1 to 2 that have passed through the regulating member 6 are conveyed in a thin layer while being supported by the rfla roller 5, and this! The -ner layer 2a is transported to a developing region between a drum-shaped photoreceptor 7 rotating clockwise and a developing roller 5, and the -ner is formed on the photoreceptor 7. The latent image is electrostatically transferred to the electrostatic latent image, and the latent image is made into a visible image.The toner that has passed through the development area without transferring to the photoreceptor 7 is transported to the toner container 1 side again.

The developing operation is performed as described above, and the VAaa roller 5 and the photoreceptor 7 are pressed against each other with a thin layer of toner interposed therebetween, and the two are in contact with each other with a width extending in the rotation direction or circumferential direction. This width is the actual nip width W, and whether this width is too large or too small, the visible (visible) formed on the photoreceptor 7
The image quality of the image will deteriorate.

How to obtain the appropriate developing nip width.

It is desirable that at least a surface portion of at least one of the image roller 5 and the photoreceptor 7 is configured to be elastically deformable. Therefore, in this example, the developing roller 5 is
g A developing roller 5 consisting of a roller shaft 5d made of an electrically conductive metal ring and an elastic layer 5b made of rubber or the like on the outside thereof.
It is assumed that the surface portion of the photoreceptor 7 has elasticity, and the surface of the photoreceptor 7 is also made of a rigid body. Further, as shown in FIGS. 2 and 3, the developing roller (toner carrier) 5 is rotatably supported by the side walls 1a, 'lb of the toner container l, and this supporting member (in this example, the toner container 1) A hook portion 1d protruding from this is engaged with a support pin 8 fixed to the frame of the image forming device, whereby the entire unit-shaped developing device is supported so as to be swingable in the direction of the arrow. Ru. Further, a pressing means consisting of compression coil springs 10° and 11 is disposed between the rear IC of the container 1 and a fixed part 9 such as the frame of the image forming device. It is being pushed towards 7. In this case, in the conventionally proposed configuration, the toner container is biased toward the photoreceptor 71 by the pressing means, so that the developing roller 5 is elastically pressed against the photoreceptor 7 only by the force of the pressing means. , to obtain a predetermined developing nip width. If the photoreceptor 7 and the developing roller 5 are formed in an ideal shape for their width, in this example an ideal cylindrical shape, the developing roller 5 and the photoreceptor 7 can be formed in that shape using only the configuration according to the conventional proposal. Spring 1 can be pressed with uniform pressure in the longitudinal direction.
By appropriately adjusting the spring force of 0°11, it is possible to always maintain an appropriate developing nip width and obtain a uniform 1° visible image. However, in reality, the developing roller 5 and the photoreceptor 7
It is said that the form deviates from the ideal form due to errors during the manufacturing process. Figures 4(a) to (c)
) and FIG. 5 illustrate the misaligned state of the developing roller 5, and the developing roller 5 shown in FIG. 4(a) is
The right end portion thereof is eccentric with respect to the roller shaft 5a (more precisely, its axis X), and the right side portion is offset by the difference a−b between the maximum diameter a and the minimum diameter. In the example shown in FIG. 4(b), both ends of the developing roller 5 are aligned a-b. In FIG. 4(c), the left and right ends of the roller 5 are bent in opposite directions by a distance ab.

In the example shown in Figure 5,! 51. The form of the image roller 5 itself deviates from the ideal cylindrical form shown by the dashed line by a maximum of C, and this is called uneven cylindricity. If the cylindricity is uneven, the position of the axis of the roller does not matter, but only the deviation from the ideal roller shape is the problem, and the deformation state of the developing roller is considered. In addition, since the surface of the developing roller has irregularities, the diameter of the roller may not be constant over the entire longitudinal direction, and this is called unevenness in straightness. If there is a misalignment in the form of the developing roller 5 (or the photoreceptor), even if the toner container is urged by the springs 10 and 11 and the developing roller is brought into pressure contact with the photoreceptor, the developing roller (or the photoreceptor) Because the protruding parts in the radial direction strongly contact each other, they cannot contact with uniform pressure, and the state of pressure changes as the developing roller rotates. It becomes non-uniform over the direction or changes periodically. For this reason, the density of the developed visible image becomes non-uniform, and there is a risk that white spots may occur.

Therefore, in the developing device according to the present invention, the developing roller 5
The developing roller 5 is configured to be pressed against the photoreceptor 7, and in the example shown in FIG. 1, one end of the developing roller 5 is pressed. That is, as is clear from FIGS. 2 and 3, bearings 2 are provided at each end of the roller shaft 5a as necessary.
0.20a is attached, and this part fits into the hole 21.21a bored in the toner container 1.
1 is formed as a horizontally elongated hole in FIG. 2, and a roller shaft portion fitted therein is supported so as to be able to move slightly in the horizontal direction. Further, as shown in FIG. 2, a pressure arm 23 is rotatably supported on one side wall 1a of the toner container l via a pin 22.
Each end of a pressure member consisting of a tension member 24 is engaged with one end of the arm 2 and the side wall 1a of the container.
3 is given a rotational habit in the clockwise direction in FIG. There is. With this configuration, the developing roller 5 has springs to and 1t.
The toner container 1 is not only pressed against the photoreceptor 7 from the fixing part 9 side by the pressing force F, , F2 caused by the
The photoreceptor 7 is pressurized by the spring 24 as shown by F3. For this reason, spring 10. If the spring force of IL, 24 is appropriately selected, the rotating developing roller 5 and photoreceptor 7 may be slightly deformed from their ideal forms.

The developing roller 5 is pressed against the photoreceptor 7 by the pressure applied by the spring 24.
It is possible to follow this and always make contact with a substantially uniform pressure over the entire length direction. Therefore, the developing nip width W can always be maintained at an appropriate value and its fluctuation can be suppressed. This makes it possible to prevent or suppress the occurrence of density unevenness and white spots in visible images.

If two or more springs 10, 11 are used as in the illustrated embodiment and provided at positions corresponding to both ends of the developing roller 5, uniform pressure contact between the developing roller 5 and the photoreceptor 7 can be easily achieved. realizable. Further, a long hole 21 is formed in the toner container 1,
Since the end of the roller shaft 5a is movably fitted here, a gap is created by the elongated hole 21 as can be seen from FIG. Since the sealing member 25.25a is provided, this sealing member 25 is provided with the elongated hole 2 as shown in FIG.
1 can be closed, thereby preventing the inconvenience of the toner inside the container 1 flowing out. The stroke by which the end of the roller shaft 5a can move through the elongated hole 21, that is, the gap between the elongated holes 21 in the horizontal direction in FIG. It is necessary to make the roller 5 follow this deviation to ensure uniform pressure contact with the photoreceptor 7, but the total amount of this deviation is actually an extremely small value, and therefore the gap between the long holes 21 is also small. Therefore, this gap can be sufficiently closed by the ordinary sheet member 25.

In the above embodiment, only one end of the developing roller 5 is pressed by the spring 24, and the reason is as follows.

A gear 26 is fixed to the end of the roller shaft opposite to the side where the spring 24 is located, and another gear (not shown) meshes with this gear, and these gears cause the developing roller 5 to move as shown in FIGS. 1 and 2. is rotated counterclockwise at . When this gear 26 is driven.

It is normal for the driving torque to fluctuate, albeit slightly. Therefore, if the hole 21a into which the drive-side roller shaft end fits is made into a long hole like the hole 21, and if this roller shaft end is made movable and pressurized with a spring, then the fluctuation of the drive torque will be Accordingly, the pressure with which this roller shaft end comes into contact with the photoreceptor 7 fluctuates, and there is a possibility that uniform pressure contact between the developing roller 5 and the photoreceptor 7 may be inhibited. Therefore, in the illustrated example, the hole 21a is not made into a long hole, and the end of the roller shaft fitted therein is prevented from moving relative to the toner container 1, thereby preventing fluctuations in the pressure contact force between the developing roller 5 and the photoreceptor 7. The side that is not affected by pressure fluctuations, that is, the end side of the developing roller opposite to the driving side is pressurized by a rib 24. The same applies when a transmission member other than a gear, such as a pulley, is used.

Of course, depending on the case, the end of the image roller on the drive side may be pressed by a pressure member, or both the drive side and the non-drive side may be pressed by a pressure member.

In the experiment, the elastic layer 5b had a rubber hardness of 46°, and one side deflection was 50μ (see Figure 4(a)), and the unevenness of cylindricity was 10μ.
A developing operation was performed using a developing roller (see FIG. 5) and a photoreceptor with a one-sided deflection of 50 μm and a cylindricity unevenness of 10 μm. In the case of the conventional developing device without the spring 24, when the pressing force of the pressing means (spring 11) was set to 2 kg, white spots occurred over 50 mm in the longitudinal direction of the developed visible image.

Using the illustrated developer having spring 24, spring 10.
The applied force of spring 24 is 1.5 kg, and the applied force of spring 24 is 30 kg.
When set to 0g, a high quality visible image without any omissions was obtained. Also in this experiment.

The movable stroke of the end of the roller shaft on the side where the spring 24 is provided, that is, the gap between the elongated holes 21 is! i5 light body.

0, 1, which corresponds to approximately the total amount of deviation in the form of the developing roller.
It is sufficient to set the gap to mm, and it has been found that a gap of this size does not affect the sealing performance of the toner at all.

In the illustrated embodiment, a developing roller is used as an example of the toner carrier, but the present invention can also be applied when this carrier consists of a bell 1-, and when the latent image carrier consists of a belt hung around a roller. Alternatively, the present invention can be similarly applied when at least the surface portion of the latent image carrier is elastically deformable, or when the latent image carrier is composed of a dielectric drum or a dielectric belt.

The pressurizing means for pressurizing the support member of the toner carrier (1-toner container in the embodiment) is not limited to a coil spring, but may be any suitable elastic means such as a leaf spring or a gas spring. Similarly, as for the pressure member for pressurizing the toner carrier, which can be appropriately selected in its arrangement position, any suitable means other than the tension spring 24 can be used. Instead of supporting the entire developing device so that it can rotate, it may be supported so that it can move in parallel toward the latent image carrier.

According to the present invention, due to the simple structure, even if the toner carrier or the latent image carrier has a shape shift or deformation,
By compensating for this, an appropriate developing nip width can be ensured, making it possible to obtain a high-quality visible image.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a developing device according to the present invention, FIG. 2 is a side view of this fl device, and FIG. 3 is a m-
FIGS. 4A, 4B, and 4C are explanatory diagrams illustrating the deflection state of the RFL image roller; FIG. FIG. 5 is an explanatory diagram illustrating unevenness in cylindricity of the Tfl image roller. 1... Toner container Figure 1 Figure 2 Figure 4

Claims (5)

[Claims] (1) A toner carrier carrying a thin layer of toner,
In a developing device that makes the electrostatic latent image on the latent image carrier visible by bringing it into pressure contact with the latent image carrier through the toner thin layer, a support member that supports the toner carrier is placed against the latent image carrier. The developing device is characterized in that the toner carrier itself is pressed against the latent image carrier by a pressing member. (2) The developing device according to claim 1, wherein the support member is a toner container containing toner. (3) The developing device according to claim 1 or 2, wherein at least a surface portion of at least one of the toner carrier and the latent image carrier is elastic. (4) The developing device according to any one of claims 1 to 3, wherein at least one end of the toner carrier is pressed by the pressure member. (5) A driving force is applied to the toner carrier from one end thereof to rotationally drive the carrier, and the pressure member presses the end of the toner carrier opposite to the drive side. The developing device according to any one of Items 1 to 4.