JPH04369678A - Image forming device - Google Patents

Abstract

PURPOSE:To always stably execute excellent image forming operation by disposing a means which cools a cleaning device in at least one cleaning device. CONSTITUTION:In an image forming device where plural image forming parts respectively having image carriers 1a-1d and the cleaning devices 5a-5d provided with cleaning blades 18a-18d eliminating toner left on the surface of the image carriers after transfer, the cooling means 26 is disposed in the prescribed cleaning device. Then, the cooling means 26 is provided with a thermistor 21 fitted to the blades 18a-18d or the thermistor 21 fitted to the casings of the devices 5a-5d. Thus, the defect of cleaning, the chatter of the tip edge of the blade and the turning-over of the blade based on the change of abutting pressure caused by the change of impact resiliency ratio every blade caused by the heating of the blades 18a-18d based on heat radiation from a fixing device or the like can be evaded and the image can be excellently formed.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

[Field of Industrial Application] The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a color image forming apparatus that repeats an image forming process multiple times on a single sheet of transfer material. It is something.

0002

[Prior Art and Problems to be Solved] "FIG. 10" is a schematic side view showing the configuration of the above-mentioned color image forming apparatus suitable for applying the present invention. A conveyor belt 8 is suspended and runs in the direction of arrow B in the figure, and above the belt 8 in the figure, four image forming units Pa, Pb, Pc, and Pd are arranged.

[0003] Each image forming section has image carriers 1a and 1b, respectively.
, 1c and 1d are disposed to face the belt 8, and primary chargers 15a and 15 are provided around the image carrier, respectively.
5b, 15c, 15d, image signal applying means 16a, 16b, 16c, 16d such as a laser beam scanner, developing devices 3a, 3b, 3c, 3d, cleaning devices 5a, 5
b, 5c, and 5d, and furthermore, a transfer charger 4a, and a transfer charger 4a are provided at opposing positions on the opposite side of each image carrier when viewed from the belt 8.
4b, 4c, and 4d are arranged.

The developing units 3a, 3b, 3c, and 3d store toners of black, magenta, yellow, and cyan colors, respectively, and each color is processed through a well-known image forming process in accordance with each color component image of the document. It is assumed that a toner image of .

Briefly explaining the operation of this device, when a transfer material such as paper passes through the pair of registration rollers 13 and arrives at the transfer site where the image bearing member 1a and the transfer charger 4a of the image forming section Pa face each other, this The black toner image formed on the image carrier 1a by this time is transferred to the transfer material.

Next, when this recording material arrives at the transfer site of the image forming section Pb where the image carrier 1b and the transfer charger 4b face each other, the toner of the magenta component color that has been formed on the image carrier 1b by this time is removed. The image is transferred to the recording material in a manner superimposed on the black toner image.

[0007] Similarly, when the recording material advances in the illustrated manner and reaches the image forming portions Pc and Pd, the yellow and cyan toner images are transferred at the respective transfer portions to form a color image, and then a color image is formed. The recording material carrying the color image is neutralized by a separation charger 61, leaves the belt 8, and is conveyed to the fixing device 7, where it is formed as a nip between a fixing roller 19 having a heat source and a pressure roller 20. The color toner image is heated and pressurized at the fixing section where the color toner image is fixed and fixed on the recording material, and then discharged outside the machine. Note that reference numeral 11 in the figure indicates a cleaning member such as a fur brush for removing toner adhering to the conveyor belt 8.

During the above transfer process, residual toner that is not transferred to the recording material and remains on the image carrier is removed by cleaning devices 5a to 5d, respectively, and each image carrier is ready for the next image forming process. Become.

In such a color image forming apparatus, in order to maintain good image quality characteristics such as hue, value, and chroma of a color image, it is necessary to sufficiently dissolve and mix each color toner. In order to sufficiently heat the recording material and the toner image carried thereon, it is necessary for the heat source to have a large heat capacity, and this tends to cause a significant rise in the temperature of the surrounding atmosphere.

Therefore, in an apparatus having a long development and transfer area as described above, a temperature gradient occurs with a peak near the fixing area as shown in the lower part of FIG. A temperature difference between Ta and Td (Tf>Td≧Tc≧Tb≧Ta, where Tf is the surface temperature of the fixing roller 19) occurs between the cleaning blades 18a, 18b, 18c, and 18d.

[0011] By the way, urethane rubber is widely used as a cleaning blade for the cleaning device of this type of image forming apparatus, but as shown in the graph of "Fig. The dependence is large, and in the case of the configuration shown in the figure, the repulsion elasticity modulus of the cleaning blades 18a to 18d satisfies ea≦eb≦
The relationship is ec≦ed, and the pressure force applied to the image carriers 1a to 1d varies, and the cleaning action also varies depending on the cleaning device. Therefore, image quality deterioration due to poor cleaning can be avoided at positions where the pressure force is weak. This may cause problems such as vibration of the blade or curling of the blade.

[0012] In order to avoid such problems, conventional methods have been taken such as appropriately increasing the contact pressure of the blade in the low-temperature area against the image carrier. , due to the temperature rise of the blade near the fixing site and the resulting increase in the rebound modulus, there is no measure to prevent wear of the blade edge due to excessive contact pressure of the blade on that side, damage to the photosensitive layer on the surface of the image carrier, etc. Without,
There is no other way than to say that it is difficult to say that this is an essential solution.

The present invention has been made in view of the current situation, and provides an image forming apparatus having a plurality of image forming sections each having an image bearing member, an image forming member attached thereto, and a cleaning device. By cooling the cleaning device of each image forming section, it is possible to avoid the above-mentioned temperature gradient and the problems described above caused by this, and to maintain stable and good image forming operations at all times. The object of the present invention is to provide an image forming apparatus that can perform the above operations.

[0014]

[Structure of the invention]

[Technical Means for Solving the Problems and Their Effects] In order to achieve the above object, the present invention provides a plurality of images each having a cleaning device each having an image bearing member and a cleaning blade for removing residual toner adhering to the image bearing member. An image forming apparatus including a forming section is characterized in that at least one cleaning device is provided with means for cooling the cleaning device.

[0015] With this configuration, it is possible to avoid the occurrence of poor cleaning, blade vibration, blade curling, etc. caused by changes in the repulsion elasticity modulus due to heating of the cleaning blade, and the cleaning blade,
It becomes possible to extend the life of the image carrier.

[0016]

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a schematic side view of a color image forming apparatus showing an embodiment of the present invention, and its basic configuration is the same as that shown in FIG. Parts are shown with the same reference numerals, and explanations thereof will be omitted unless necessary.

Because of this configuration, as described above, the cleaning device 5d of the image forming section Pd closest to the fixing device 7 reaches a high temperature, and the cleaning blade 18d is also affected by the heat the most. Since the contact pressure against the image carrier becomes strong, a cooling means such as a thermistor 21 and a cooling fan 26, part of which is shown in the figure, is provided to avoid the adverse effects of heat. .

"FIG. 2" is an enlarged side sectional view showing the cleaning device in the image forming section Pd, in which the image carrier 1d is
A cleaning device 5d is disposed adjacent to the cleaning device 5d, and the free edge of a cleaning blade 18d attached to the cleaning device 5d is placed in pressure contact with the image carrier 1d.

When the residual toner generated at the transfer site (not shown) comes to the position of the cleaning blade 18d as the image carrier 1d rotates, it is scraped off and removed by the cleaning blade 18d, and is guided by the scooping sheet 24d to the conveying screw 23d. position and is discharged to the outside by the conveying screw.

In such a cleaning device, as shown in the figure, a thermistor 21 is disposed on the cleaning blade 18d, thereby causing the cleaning blade 18d to
Detects the temperature of When this detected temperature exceeds a preset temperature, the cooling fan 26 is driven by this output signal, and when the temperature falls below the set temperature, the fan is turned on and off by the control circuit 25. This prevents the temperature of the cleaning blade 18d from rising. With this configuration, it is possible to prevent an excessive temperature rise of the cleaning blade and an unreasonable increase in blade pressure caused by this.

"FIG. 3" shows the relative arrangement of the cleaning device 5d and the cooling fan 26, viewed from the image carrier side (
(upper row) and the temperature distribution in the longitudinal direction of the cleaning blade (lower row). This can prevent the temperature of the cleaning blade 18d from rising. However, when the fan 26 is placed near the center of the cleaning blade 18d as shown in the figure, the central part and both ends of the blade 18d are It is unavoidable that a slight temperature difference (T1-T2) will occur between the area and the vicinity of the area.

[0022] If the temperature difference that occurs in this case is too large,
Since there may be local differences in the lifespan of the blades and the image carrier, a plurality of cooling fans (in the case shown, three with numbers 26A, 26B, and 26C) are installed as shown in "Figure 4".
It is preferable to arrange these so that air is blown uniformly in the longitudinal direction of the blade 18d. With this configuration, the temperature difference (T3-T4) of the cleaning blade can be reduced.
can be made smaller (|T1-T2|>|T3-
T4｜).

In the above device, the thermistor is attached to the cleaning blade, but if this may change the state of pressure contact of the blade to the image carrier, it may be necessary to attach the thermistor at an appropriate location near the blade. You can also do this.

[0024] Furthermore, as the cooling means, a Peltier element can be used in addition to the above-mentioned cooling fan, thereby making it possible to miniaturize the structure.

Furthermore, without using a thermistor, the cooling fan is configured to turn off the cooling fan after a predetermined time has elapsed after turning on the power switch of the apparatus main body, and to stop the cooling fan when the power switch is turned off. It is easy to understand that it is also possible to detect the temperature at a suitable location within the fixing device and turn the cooling fan on and off accordingly.

"FIG. 5" and "FIG. 6" show other embodiments, in which "FIG. 5" is a side view and "FIG. 6" is an end view seen from the image carrier side.

In this device, the thermistor 21 is covered with a dust-proof cover 22 and attached to the casing of the cleaning device 5d, and the casing is further provided with a heat pipe 28 having fins 30 arranged at the end by a support member 29. is attached.

According to the output of a thermistor 21 serving as a temperature detection means, the control device 25 controls the air blowing of the cooling fan 26 toward the fins 30 to prevent the temperature of the cleaning blade 18d from rising.

By arranging the heat pipes in the longitudinal direction of the cleaning device in this manner, the temperature distribution of the cleaning blade can be made uniform over the entire length, and the cleaning blade can be brought into more uniform pressure contact with the image carrier.

"FIG. 7" is a schematic side view of a color image forming apparatus showing still another embodiment, and the image forming process etc. are the same as that shown in "FIG. 1". Explanation of them will be omitted.

In this apparatus, each image forming section Pa,
Pb, Pc, Pd cleaning devices 5a, 5b, 5c
, 5d, thermistors 21a, 21b, 21c,
21d and cooling fans 26a, 26b, 26c, 2
Temperature control means including 6d are provided.

As shown in FIGS. 8 and 9, the thermistors 21 provided in each of the cleaning devices 5a to 5d
By independently turning on and off the cooling fans 26a to 26d according to the output signals detected by the cleaning blades 18a to 21d, the temperature of each cleaning blade 18a to 18d is maintained uniformly, and the pressing force to the image carrier is uniform. It can be done.

[0033]

As explained above, according to the present invention, a plurality of image forming sections each having an image bearing member and a cleaning device equipped with a cleaning blade for removing residual toner remaining on the surface of the image bearing member after transfer are provided. In image forming apparatuses, by disposing a cooling means in a predetermined cleaning device, it is possible to reduce contact pressure based on changes in the repulsion elasticity modulus of each blade due to heating of the cleaning blade due to heat dissipation from the fixing device, etc. Poor cleaning,
It is effective in obtaining high-quality images by avoiding problems such as chatter at the blade tip edge and blade curling, and it also prevents damage to the cleaning blade and image carrier, increasing durability. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a color image forming apparatus showing an embodiment of the present invention.

[Figure 2] Side view of the cleaning device used in the above

[Figure 3] and

[Fig. 4] An explanatory diagram showing the arrangement of the cooling fan as above.

[Figure 5
】and

FIG. 6 is a schematic diagram showing another embodiment.

FIG. 7 is a schematic side view of a color image forming apparatus showing another embodiment.

[Figure 8]

[Figure 9] Model diagram showing another embodiment

FIG. 10 is a side view showing the configuration of a known color image forming apparatus.

[Figure 11] Graph showing changes in rebound modulus due to temperature changes for each cleaning blade as above.

[Explanation of symbols] [Explanation of symbols]

1a to 1d
Image carriers 3a to 3d
Developing units 4a to 4d
Transfer charger 5a to 5d
Cleaning device 7

Fixing device 8
Conveyor belts 18a to 18d
cleaning blade

Claims (3)

[Claims] 1. An image forming apparatus including a plurality of image forming sections each having a cleaning device each having an image bearing member and a cleaning blade for removing residual toner adhering to the image bearing member, in which at least one of the cleaning devices An image forming apparatus provided with means for cooling the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the cooling means includes a thermistor attached to the cleaning blade. 3. The image forming apparatus according to claim 1, wherein the cooling means includes a thermistor attached to a casing of the cleaning device.