JPS61141475A - Image forming device - Google Patents

Abstract

PURPOSE:To extend the service life of a photosensitive body and to minimize the deterioration of a cleaning blade by adjusting the blade pressure of the cleaning blade to be brought into press contact with the photosensitive body in accordance with the kind of the toner used for development. CONSTITUTION:A developing device 3A is assumed to be a developing device contg. a toner requiring the high blade pressure in the stage of cleaning, for example, a non magnetic red toner and a developing device 3B is assumed to be a developing device contg. the toner cleanable under the lower blade pressure in the stage of cleaning, for example, a magnetic black toner. A means 30 for detecting the kind of the toner is provided in order to discriminate the color of the toner con- tained in the developing device mounted to the image forming device. A driving means 18 turns counterclockwise a blade holer 12 around a shaft 13 via a spring 17 and a lug member 16. The top end of the blade 15 is thereby moved toward a photosensitive drum 1 and the blade pressure of the cleaning blade toward the surface of the pbotosensitive body is changed according to the kind of the selected developer.

Description

Detailed Description of the Invention Shin-1-1 The present invention forms a toner image on, for example, a photoreceptor as an image carrier, transfers the toner image to a medium such as paper or a transparent film, and transfers the toner image to a medium such as paper or a transparent film. This relates to an image forming apparatus in which residual toner is removed by a cleaning device and the photoconductor can be reused, and in particular, it is a color electronic copying device or a color electronic copying device that uses a plurality of developers and is equipped with a cleaning device that follows a blade cleaning method. The present invention relates to an image forming apparatus such as a color printing machine.

Generally, according to an image forming apparatus according to an electrophotographic method, an image forming process of charging → exposure → development, or an image forming process of primary charging → secondary charging/M light → development, or various other methods. An image is formed on the photoreceptor.

The image is transferred to a medium called a transfer material, such as ordinary paper or a transparent film, to obtain a copy or printed matter.

On the other hand, the toner image on the photoreceptor is not 100% transferred to the transfer material, and toner remains on the photoreceptor. In order to repeatedly reuse a photoreceptor, a cleaning device is required to remove residual toner that has not been completely transferred on the surface of the photoreceptor.

Currently, the most widely used cleaning method for various electronic copying machines on the market is to press a blade against the photoreceptor surface because of its simple structure and high efficiency. This is a blade cleaning method that scrapes off residual toner.

Cleaning devices using such a blade cleaning method are frequently used in color copying machines, color printing machines, etc., which have a plurality of developing units each containing a different color of developer.

In a cleaning device using a blade cleaning method, the blade pressure exerted on the photoreceptor by the blade must generally exceed a value equal to or higher than the above value to remove residual toner on the photoreceptor surface to the extent that the surface of the photoreceptor can be regenerated. I understand. On the other hand, if the blade pressure is too high,
Naturally, this degrades or damages the surface of the photoreceptor.

The blade pressure is determined by the developer, that is, components such as pigments that make up the toner, for example, if the toner is magnetic, the tripo is 18K.
For non-magnetic toner, the adhesion force to the drum is different due to the tripo difference of about 28 kV, and non-magnetic toner requires a higher blade pressure. Further, even when the external additive is smaller than the toner particle size, high blade pressure is required to clean the external additive. Therefore, the blade pressure of conventional cleaning devices is set in accordance with the blade pressure for toner, which requires the heaviest blade pressure, which has the disadvantage of shortening the life of the photoreceptor and causing severe deterioration of the blade itself.

Accordingly, an object of the present invention is to provide an image forming apparatus equipped with a blade cleaning device that extends the life of a photoreceptor and minimizes blade deterioration.

Another object of the present invention is to provide a color cleaning blade having a plurality of developers, that is, a plurality of development units, in which the blade pressure of the cleaning blade against the surface of the photoreceptor can be changed in accordance with the type of one selected developer. An object of the present invention is to provide an image forming apparatus.

uu divination -- Various objects are achieved by the present invention. To summarize, the present invention is capable of adjusting the blade pressure of the cleaning blade pressed against the photoreceptor in accordance with the type of toner used for development. This is an image forming apparatus characterized by comprising a blade cleaning device.

According to a preferred embodiment of the present invention, the blade pressure is controlled by a signal from a detection and discrimination means that discriminates the type of toner in the developer.

Next, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

As described above, the image forming apparatus according to the present invention can be suitably applied to a multi-color or full-color electrophotographic copying apparatus, a color recording apparatus for a computer output section, etc., but in this embodiment, For example, the present apparatus will be described as being applied to a color electrophotographic copying apparatus for obtaining two-color images of black and red.

Fig. 2 shows a schematic cross-sectional view of a color electrophotographic copying device for obtaining two-color images of black and red. First, the overall configuration of the color electrophotographic copying device will be explained. A photosensitive drum 1 having an electrophotographic photosensitive layer formed on its surface is disposed in a section. The photosensitive drum l has a rotation support shaft (with a rotation center 0) in a well-known manner.
(not shown) is rotatably and removably attached to the
In this embodiment, it is assumed that the photosensitive drum 1 rotates in the direction of arrow X, that is, clockwise in FIG.

A primary charger 2 is located approximately directly above the photosensitive drum 1, a multicolor developing device 3 is located on the right side of the photosensitive drum 1 in FIG. 2, and a transfer discharger 4 and a transfer discharger 4 are located approximately directly below the photosensitive drum 1. A cleaning device 10 is disposed on the second left side portion. An optical system 5 is disposed in the upper part of the electrophotographic copying device, and an optical system 5 is arranged in the upper part of the electrophotographic copying apparatus, and the original image is transferred onto the photosensitive drum 1 at an exposure section E located between the primary charger 2 and the multicolor developing device 3. configured to project. Optical system 5 can use any optical system. Further, a light source 6 for erasing residual charges on the photosensitive drum 1 is provided between the primary charger 2 and the cleaning device IO.

Since the color copying apparatus described here is a color electrophotographic copying apparatus for obtaining two-color images of black and red as described above, the multicolor developing device 3 includes two developing units, ie, developing units 3A and 3B. However, the configuration is not limited to this, and it is also possible to have three or more developing units.

A color electrophotographic copying apparatus configured as described above.

The operation will be briefly explained.

The photosensitive drum 1 begins to rotate in the direction of arrow X at the start of operation, and is charged by the primary charger 2 .

The charged photosensitive drum 1 further rotates, and an optical image is slit-exposed at the exposure section E by the action of the optical system 5, so that electrostatic latent images of each color are formed on the photosensitive drum 1. photosensitive drum l
The upper latent image is then brought by rotation of the photosensitive drum 1 to a development area where a multicolor development device 3 is arranged. In the multicolor developing device 3, the electrostatic latent image on the photosensitive drum 1 is developed as a toner image.

The toner image on the photosensitive drum is transferred to a transfer material P fed from a paper feeding device (not shown) in a transfer area T where a transfer discharger 4 is arranged. The transfer material P carrying the toner image is then conveyed to a fixing device (not shown) and fixed thereon.

The residual toner on the photosensitive drum l having residual toner is removed by a blade cleaning device 10, and then the photosensitive drum 1 is subjected to the action of a light source 6, after which the next image forming process is performed again.

The developing devices 3A and 3B have substantially the same configuration, but the developing device 3A contains toner that requires high blade pressure during cleaning, such as non-magnetic red toner, and the developing device 3B contains toner that requires high blade pressure during cleaning. Assume that the developing device contains toner, such as magnetic black toner, which can be cleaned with a lower blade pressure.

As shown in FIG. 1, the copying apparatus also includes a toner type detection means 30 for determining which color toner the developing device currently installed in the copying apparatus contains. is provided. The toner type detection means 30 can use various devices, but in this embodiment, one of the devices is used for each developing device.
It is composed of a concave-convex code member 32 formed as a section, and a well-known photointerrupter 34 that engages with the concave-convex code member 32 in a non-contact manner and reads signals from the concave-convex code member 32. Such toner type detection means 30 is provided in each developing unit 3A and 3B.

Blade cleaning next? cilO will be explained with reference to FIGS. 1 and 2.

The blade cleaning device 1O includes a cleaning container 11 that receives the removed residual toner on the photoreceptor, and a blade holder 12 that is pivotally connected to the container 11 by a shaft 13.
and a blade 15 attached to the blade holder 12 by a presser plate 14. The blade 15 is a rectangular elastic member that extends approximately in the width direction of the photosensitive drum l, and its free edge extends toward the photosensitive drum l so that it can be pressed against the photosensitive drum l.

An ear member 16 is integrally formed approximately in the center of the grade holder 12, as best illustrated in FIG. are concatenated. The drive means 18 is fixed to the cleaning container ll.

In the above configuration, normally the driving means 18, that is, the solenoid is in an OFF state, and the blade 15 is applied with a linear pressure 11 that can clean the magnetic toner by lightly hitting the photoreceptor.
When the developing device 3A is selected, the toner type detection means 30 outputs a signal to increase the blade pressure (solid line position in Figure 3). The signal is transmitted to the cleaning device 10 and energizes the driving means 18 .

Drive means 18, via spring 17 and ear member 16, rotate blade holder 12 about axis 13 in a counterclockwise direction in FIG. As a result, the tip of the blade 15 is moved toward the photosensitive drum 1 (as shown by the dashed line in Figure 3).
Cleanable linear pressure 16 for non-magnetic toner,
Blade pressure is increased to 5 g/cm.

When the copying operation is completed at the blade position, the drive means 18 is turned off and the blade returns to the low blade pressure position, that is, the solid line position in FIG. 3.

When the developer 3B is selected, the drive means 18 is not activated, and therefore the cleaning device operates with low blade pressure.

The toner accumulated in the cleaning container due to this leaning operation is discharged from the outlet 21 by the extraction screw 2°.

In this embodiment, examples using magnetic and non-magnetic toners are shown, but it is also necessary to change the blade pressure depending on the difference in the particle size of the additive. - For example, if strontium stannate, which is one-tenth of the toner particle size, is added as an external additive, the blade pressure must be increased by 20% compared to the toner without blade pressure.

4r14 illustrates another embodiment of the blade cleaning device 10. In this embodiment, the blade drive means 18 consists of a reversible motor 22, a pulley 23 mounted on the output shaft of the motor, and a wire 24 wound around the pulley, the free end of the wire 24 being connected to a spring. 25 to the ear member 16 of the blade holder 12.

Therefore, by rotating the motor 22 forward or backward, the blade 15 is moved between the high blade pressure position (double-dashed line position) and the low blade pressure position W (solid line position), as in the first embodiment. It is said to be movable.

Further, a protrusion 26 is integrally formed on the blade holder 12, while detectors 27 and 28 are fixedly attached to the cleaning device.
is installed. The detectors 27 and 28 act on the protrusion 26 of the blade holder 12 to detect the position of the protrusion 26.

In the above configuration, when a developing unit requiring low blade pressure is selected, the protrusion 26 is held at a position where it can be detected by the detector 27. If a developing unit that requires high blade pressure is selected, the motor 22 rotates until the protrusion 26 is detected by the detector 28, and when the development with toner that requires high blade pressure is completed, the blade pressure increases. To return the pressure to a lower pressure, the motor 22 is reversed until the protrusion 26 is detected by the detector 27.

In the above description, a plurality of developing units are installed in the main body of the apparatus, but the image forming apparatus may be of a type in which one developing unit is replaced.

Further, in the above embodiment, the blade 15 is always in pressure contact with the photoreceptor l, but it is normally held in a non-pressure state, and may be in pressure contact during operation.For example, in the first embodiment, This can be achieved by providing a plurality of drive means, and in the second embodiment, by providing another detector for detecting the third position of the blade.

11. Since the image forming apparatus according to the present invention includes the blade cleaning device configured as described above, it has the effect of extending the life of the photoreceptor and minimizing the deterioration of the blade.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of an image forming apparatus according to the present invention. FIG. 2 is a schematic cross-sectional view for explaining the operating process of the image forming apparatus shown in FIG. 1. FIG. FIG. 3 is a cross-section showing one embodiment of the blade cleaning device. FIG. 4 is a sectional view showing another embodiment of the blade cleaning device. l: Photosensitive drum 3: Multicolor developing device lO: Cleaning device 15: Blade Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1) A blade cleaning device is provided that can adjust the blade pressure of a cleaning blade pressed against the image carrier according to the type of toner used for development. Image forming apparatus 2) The apparatus according to claim 1, wherein the setting of the blade pressure is controlled by a signal from a detection and determination means for determining the type of toner in the developing device.