JPH0224689A - Image forming device - Google Patents

Abstract

PURPOSE:To evade the wasteful consumption of toner without causing faulty cleaning by controlling toner quantity on a part except an image area which is conveyed by a cleaning blade according to an environmental condition. CONSTITUTION:Toner band forming means is controlled by a toner band forming times control means which corresponds to the number of copies by a copy counter after an environment changeover switch responds to a temperature sensor to get in a toner quantity control mode and a toner band width control means and the toner quantity on the part except the image area which is conveyed by the toner blade is changed according to humidity. Thus, the faulty cleaning can be prevented from occurring and the wasteful consumption of the toner can be evaded. The image where density is not lowered can be formed without receiving the effect of the change of humidity and the number of copying times. The same processing as in the case of the change of humidity can be performed even in the case of the change of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic recording process, such as an electrostatic copying machine and a printer.

(Prior art and issues to be solved) Is there static on the surface of the image carrier? I! After forming a latent image, toner is supplied to the latent image to develop an 8kW image, and a sheet-like transfer material such as paper is brought into contact with this toner image, and the toner image is electrostatically transferred to the transfer material. Image forming apparatuses that include the steps of are conventionally well known.

FIG. 3 schematically shows the structure of a typical image forming apparatus, in which the surface photosensitive layer of the photoreceptor 1, which extends perpendicularly to the plane of the paper and rotates in the direction of arrow A, is - The document is uniformly charged by a charger 2, and subjected to image exposure 4 using a laser beam or the like which is image-modulated by the reflected light of the light irradiating the document surface, thereby forming an electrostatic latent image.

As the photoreceptor rotates, when the latent image comes to the position of the developing device 5, toner is supplied from there, the latent image is visualized, and a toner image is formed.

Further, when this toner image reaches a transfer site having a transfer charger 7, a transfer material (not shown) is supplied to the transfer site from the conveyance path 6 at the same timing, and the transfer charger acts to charge the photoreceptor. After the toner image is transferred to the transfer material, the transfer material is conveyed to a fixing site (not shown) while carrying the toner image.

Residual toner that is not transferred to the transfer material and remains on the photoreceptor during transfer reaches a cleaning device 8, where it is scraped off by an elastic cleaning plate 8a attached to the cleaning device 8, and further, the residual charge is removed by a pre-discharging lamp 9. The photoreceptor is then ready for the next image forming process.

Incidentally, in the image forming apparatus configured as described above, it has been found that it is preferable that a suitable amount of toner always be present at the blade edge portion of the cleaning plate that comes into contact with the photoreceptor.

Of course, if the amount of this toner is too large, problems will occur such as the accumulated toner running sideways in the longitudinal direction of the edge, overflowing from the cleaning device, and potentially contaminating the transfer material and various parts inside the image forming device. However, on the other hand, if, for example, a large number of originals with a large amount of white background are copied in succession and the amount of toner consumed is low, the amount of residual toner will be reduced. The friction between the photoreceptor and the photoreceptor increases,
Poor cleaning and blade curling are more likely to occur due to chattering of the blade edge.

In addition, in the case of paper, which is often used as a transfer material, the amount of substances that are difficult to clean, such as fine paper dust, precipitated rosin, and talc, is relatively large compared to the amount of toner. may damage the photoreceptor or
There is a risk of cleaning failure.

Incidentally, in the above-mentioned image forming apparatus, a blank exposure lamp 3 is provided to prevent toner from adhering outside the image area due to image exposure of the back scan or the frame of the document table. However, it is well known that measures have been taken to turn on the light in the inter-paper area to prevent toner from adhering to non-image areas.

Therefore, as mentioned above, if the amount of toner generated from the image area is too small, turn off this lamp, apply a band of toner to this area, and transport this toner as it is to the cleaning device. Therefore, a method has been proposed in which toner is supplied to the blade edge portion.

Although such a method can be expected to have a certain effect on avoiding the problem of insufficient toner to be stored in the blade edge portion, the conventional method takes into account various conditions and It has been common practice to assume conditions that require toner and set the amount of toner to meet the conditions.

Originally, the appropriate amount of toner in the above-mentioned band should be stored on the blade edge depending on the copy mode, type of transfer material, environmental characteristics such as temperature and humidity, type of document, etc. Because of this, it is unavoidable that more toner is consumed than necessary.

For this reason, for example, in a cartridge type device, there is a limit to the amount of toner that can be stored, so the toner may run out before the end of the photoreceptor's lifespan, thereby limiting the lifespan of the cartridge itself. A situation will arise.

Furthermore, as mentioned above, the amount of band-shaped toner in the paper gap is -
In boat fishing, the amount of toner is often more than the required amount, so the amount of toner stored on the blade edge tends to be excessive, which tends to cause the above-mentioned problems.

Furthermore, the formation of the toner band portion is carried out in a manner similar to the image forming process and is therefore subject to the same environmental conditions as in the image portion.

Therefore, in a situation where a large number of copies with low toner consumption are made in a low humidity environment and the toner charge in the developing device becomes abnormally high, it becomes difficult for the toner to transfer to the photoreceptor, so This tends to cause a decrease in density and fog, and the amount of toner that should be supplied to the blade edge tends to be insufficient.In addition, in such an environment, the electrostatic adsorption force between the photoreceptor and toner becomes stronger. It becomes difficult to clean. When the humidity is high, frictional charging of the toner is difficult to occur in the development area, so only the easily charged parts of the toner components are transferred to the photoconductor, resulting in a difference in the balance of toner components, which tends to cause a decrease in density and makes cleaning difficult. Only the components tend to reach the cleaning plate. As described above, when the humidity is high or low, cleaning becomes difficult, and the amount of toner in the toner band formed between sheets tends to decrease, resulting in poor cleaning.

The present invention has been made in view of the above-mentioned current situation, and the present invention adjusts the amount of toner in a toner band formed at a position between sheets including front rotation and rear rotation according to changes in environmental conditions.
It is an object of the present invention to provide an image forming apparatus that can avoid wasteful consumption of toner without causing cleaning defects, and can perform stable cleaning at all times.

(2) Structure of the invention (technical means for solving the problem and its effect) In order to achieve the above object, the present invention provides an image forming apparatus configured to convey toner attached to a portion outside the image area to a cleaning plate. The forming apparatus is characterized in that it is provided with means for changing the amount of toner according to environmental conditions.

With this configuration, an appropriate amount of toner is always retained at the edge of the cleaning plate to provide a stable cleaning action, and it also prevents the density drop that tends to occur in low humidity or in images with low toner consumption. be able to.

(Description of Examples) The results of image forming experiments conducted under various conditions using the image forming apparatus as described above will be shown to the following persons.

Table 1 shows the toner band formation width when images are formed using domestically made transfer paper at normal humidity in a "single continuous" manner, that is, by repeatedly copying one sheet and then pausing for a few seconds. This is a conventional example in which the control of the number of times, that is, the number of copies to make one indentation of the toner band, was studied.

In the upper table of Table 1, the O mark indicates a good result and the X mark indicates a poor result.
In the area to the right of the dotted line, cleaning failure occurred due to lack of toner. Furthermore, in the region to the left of the chain line, excessive toner causes toner to fall near the transfer paper conveyance site and the transfer site (the meanings of the 0-dot line and the chain line are the same below).

Table 2 shows transfer paper made in Scandinavia (size 11X).
An embodiment is shown in which the number of toner band formations and rlJ are controlled under all the same conditions such as environmental conditions, copy mode, and copy density, except that a toner band (RlFinch) is used.

Since the transfer paper in Table 2 is made in a foreign country, it contains a lot of paper powder and is difficult to clean, so it is understood that a large amount of toner is required for the toner band, and the boundaries thereof are shown by dotted lines.

Table 3 shows a test conducted in a low humidity environment (25° C., 10% RH) using domestic paper and single continuous copying. In such a case, as mentioned above, the copy density is small (0
, 9), the range where good leaning can be performed (O part) is shifted to the left compared to the case in Table 1 above.
In other words, it can be seen that a good leaning effect can be obtained by supplying a larger amount of toner to the inter-sheet toner band. Furthermore, even if the amount of toner is increased, toner overflow is less likely to occur than in the case of Table 1.

Tables 3 and 4 show the results of tests conducted under the same conditions as in Table 3, except that foreign-made transfer paper was used.

There is a lot of paper dust on the 4th front transfer paper and the copy density is low (0,9)
It can be seen that cleaning is difficult and requires a larger amount of toner than in the case of Table 3.

Note that the range in which toner overflows and falls is not significantly different from the previous example.

Table 5 shows test results under the same conditions as in Table 1 above, except that continuous copying was performed.

This is the fifth representation, and the one shown is configured to respond to changes in humidity.

The mode for controlling the amount of toner in the toner band is selected by the environment selector switch using the humidity sensor as shown in Table 6.

As you can see from the table above in Table 6, since the paper is made in one country, there is less paper dust.
For continuous copying, there is no pre-rotation or post-rotation for each copy operation, so in order to ensure that enough toner is supplied and that cleaning failures do not occur, the amount of toner required is as small as the range shown by the dotted line in the table. That's it.

On the other hand, it can be seen that even if the toner overflow and fall is controlled to form a narrow toner band, the amount of toner per cycle is large, so there is sufficient time.

FIG. 1 shows an embodiment of the present invention in which the amount of toner in the toner band between sheets is controlled according to environmental conditions, and the toner band forming means is configured such that the number and width of the toner band can be determined by the output signal. is controlled.

As this toner band forming means, for example, blank exposure, developing bias, etc. can be used, and by controlling these, the number of times the toner band is formed and the width are set.

Although we have described the case in which it responds to humidity, it is easily possible to respond to various external conditions as necessary, such as temperature, document condition, type of transfer material, etc. This would be understandable.

When the overall temperature, humidity, etc. change greatly, such as in summer and winter, toner band forming means such as blank exposure can be controlled by switching the environment selector switch, as shown in Figure 2. , you can also set it to match your environment.

(3) As described in detail, in the present invention, in an image forming apparatus equipped with a cleaning device using a cleaning plate, it is possible to constantly supply an appropriate amount of toner to the blade engine, thereby preventing cleaning failures and blades. In addition to avoiding the occurrence of curling and maintaining a stable cleaning function, it also prevents the occurrence of image density loss and blade blurring in documents with low toner consumption and in low humidity environments, contributing to obtaining high-quality images. However, it is large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment, and FIG. 3 is a schematic side view showing the configuration of an image forming apparatus suitable for applying the present invention. be. DESCRIPTION OF SYMBOLS 1...φ photoreceptor, 2...-forming charger, 3...Fist/blank exposure lamp, 4...Image signal applying means, 6...Transportation path, 7...Transfer charger, 8.・No. cleaning device, 8a・Φ・cleaning plate.

Claims (2)

[Claims] (1) An image forming apparatus configured to convey toner attached to a portion outside the image area to a cleaning plate, the image forming apparatus comprising means for changing the amount of toner according to environmental conditions. (2) The image forming apparatus according to claim 1, wherein the environmental conditions are humidity and/or temperature.