JPH0244388A - Image forming device - Google Patents

Abstract

PURPOSE:To attain always preferable cleaning effect owing to the appropriate toner amount, and to obtain a preferable picture by controlling the amount of toner in a black belt shape according to the type of transfer material and a copying condition. CONSTITUTION:In an image forming device, the toner in the black belt shape is made adhered to a non-image part, and supplied to the cleaning blade; a means which controls the amount of toner in a black belt shape according to the type of the transfer material and the copying condition is provided therein. Thus, the amount of toner which is supplied to the edge of the cleaning blade can be appropriately controlled. Accordingly, cleaning defect caused by toner shortage, and the contamination of the transfer material and each part inside of the device due to toner excess are prevented, then, always stable and preferable cleaning function can be maintained. Therefore, a preferable image can be attained.

Description

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

(Prior art and issues to be solved) A transferable toner image formed on the surface of an image carrier is transferred to a sheet-like transfer material mainly made of paper, and residual toner that has not been transferred to the transfer material at this time is elastically cleaned. Image forming apparatuses configured to repeat the removal process with a blade have been well known, but one transfer material is used to form one image.
Since the amount of toner required per sheet varies widely, various problems inevitably occur.

Among these problems, especially the cleaning property will be briefly explained with reference to FIG.

This figure is a schematic side view showing an image forming apparatus equipped with a rotating cylindrical photoreceptor having an axis extending perpendicularly to the plane of the paper, in which the surface of the photoreceptor 1 is uniformly charged by a primary charger 4. Then, an electrostatic latent image is formed by the exposure section 7.

Toner charged to a predetermined polarity is supplied to this MI image by the developing device 10 to form a toner image, and when this toner image reaches the transfer site where the transfer charger 12 is arranged, it is moved at the arrow B in synchronization with this. The transfer material 11 is guided to the transfer site and comes into contact with the photoconductor, and the toner image on the photoconductor 1 is transferred to the transfer material 11 by the action of the transfer charger 12, and then the transfer material is further moved to the left in the figure. It is assumed that the image is transported and sent to the fixing site 13.

After the transfer, residual toner that does not contribute to the transfer and remains on the photoreceptor l is
As the photoreceptor 1 rotates, it reaches the cleaning area.
The remaining charges are removed by the cleaning blade 14 and then roughly eliminated by the static eliminating lamp 3, and the photoreceptor 1 is ready for the next image forming process.

By the way, in one paper interval, that is, in the part where the photoreceptor is rotating and the transfer material does not touch the photoreceptor in the rotation direction, pack scan or one part of the frame outside the image area of the document table is image-exposed and the part outside the image area is exposed. The toner may stick to the area, wasting the toner, and forming an unsightly, irregular image on the periphery of the copy paper. In order to prevent this, it has been proposed that the blank exposure 5 be turned on between sheets of paper outside the image exposure to prevent the toner from adhering as described above.

This can prevent contamination of the transfer material, but on the other hand, documents with low toner consumption.

When copying a large number of originals that have no toner in a part of the image area, there will be areas on the surface of the photoreceptor where there is no toner at all.

On the other hand, substances that are difficult to clean, such as fine paper dust from the paper used as the transfer material and precipitates such as rosin talc, do not decrease, so they may accumulate on the cleaning blade and cause poor cleaning or damage to the photoreceptor. In some cases, these substances adhere to and harden on the photoreceptor, resulting in lower resistance due to moisture absorption and deterioration of image quality.

Therefore, in order to solve the above-mentioned problem, the blank exposure is appropriately turned off between sheets, and the corresponding part of the photoreceptor is exposed.
The toner is applied in a band shape in the axial direction (hereinafter referred to as a black band).
A method has been proposed in which the toner is brought as it is to the cleaning blade, the relative amount of foreign matter as described in ## to the toner is reduced, and this is cleaned together with the highly fluid toner.

By the way, when forming a black band in the manner described above, the amount of toner is usually set to a certain amount that corresponds to the case where the most toner is needed, assuming various copying conditions. .

For this reason, 1. Normally, the amount of toner supplied to the cleaning blade tends to be excessive, and not only is there a lot of toner wasted, but if there is too much toner, some toner reaches the cleaning device and is removed by the blade. In some cases, this may fall onto the transfer material or the conveying section, causing contamination.

In addition, cartridge-type devices, which have been gaining popularity in recent years, have a limited amount of toner in them, so using a large amount of toner to form a black band will affect the longevity of the cartridge. Since the amount of toner consumed for this purpose is directly related to this, it is necessary to keep the amount of toner consumed as small as possible.

Furthermore, single continuous copy (1
The number of rotations of the photoreceptor is higher than in continuous copying, so if you repeat single copying many times with an original that consumes little toner, the toner on the developing sleeve will be used up. Since frictional charging is repeated without being charged, the toner becomes abnormally charged, making it difficult for the toner to move from the developing sleeve to the photoreceptor, resulting in a decrease in density and fogging.

As mentioned above, in the above-mentioned A-formation image forming apparatus, it is necessary that an appropriate amount of toner is constantly supplied to the photoreceptor, and the appropriate amount of toner is used as a transfer material. It varies depending on various factors such as paper type, size, copy mode, development due to environmental changes, and changes in charging characteristics.

Let me explain these.

For example, in the copy mode, even if the same number of copies are made by repeating continuous copying and single copying, the latter requires a larger amount of toner per cleaning blade.

This is because in the latter case, in addition to the rotation of the photoreceptor necessary for copying one sheet, the photoreceptor is rotated forward and backward for each copy.

First, a single continuous copy requires approximately 1.5 to 445 times more rotations than a continuous copy.

Since toner is not supplied to the cleaning blade during the above-mentioned front rotation and rear rotation, if this toner-free state is a single continuous copy, it is different from the one in the case of continuous copying.
．． It is thought that there are 5 to 4.5 times as many.

Depending on the type of document, if there is a part of the cleaning blade that does not require toner when viewed in the longitudinal direction of the cleaning blade, toner may run out and cause the above-mentioned problems, so in the case of single continuous copying, A larger amount of toner is required per sheet than in the case of continuous copying.

Next, looking at the required toner t depending on the type of paper used as a transfer material, the ratio of talc, silica, clay, HA, etc. contained in the paper powder varies depending on the type, manufacturing method, and raw material pulp. Since the components that adhere to the surface of the carrier differ, the cleaning function of the cleaning blade will also be affected.

First of all, domestically produced paper is mostly made from bulbs made from hardwoods, and although it contains less paper powder, it tends to contain more talc.
Products made from overseas coniferous trees tend to contain a lot of paper powder and silica.

When these are used as transfer materials, in the former case, talc tends to adhere to the surface of the photoreceptor as a hygroscopic component, causing image deletion, and in the latter case, the silica component tends to damage the photoreceptor. It is necessary to appropriately increase the amount of toner used as a black belt to suit each case.

Furthermore, the size of the transfer material is different. In particular, when looking at the appropriate amount of toner due to changes in the length of the photoconductor in the rotational direction, long sheets of paper naturally emit more paper dust and the like in one operation than short sheets of paper, so the burden of cleaning becomes greater. Since this becomes noticeable in the case of a document with a small amount of toner consumption, it is necessary to use a large amount of toner for the black belt.

For example, if you make A3 size and A4 size copies of an original that consumes relatively little toner,
In the former case, a large amount of paper dust arrives at the blade in one operation, and the amount of toner consumed is small, resulting in too little toner at the blade position, and the lack of toner places a heavy burden on cleaning performance. In the latter case, the amount of toner arriving at the blade is approximately half of the former, and the next A4
It involves idling until the size of the paper arrives, and it is also possible to form a black band if necessary, so the load on the blade is considerably reduced.

As briefly described above, in an image forming apparatus equipped with a cleaning blade that comes into pressure contact with an image carrier, smooth leaning is ensured.

In order to avoid waste of torches, the manner in which the black band is formed should be determined by taking into account various conditions such as the copy mode, the 5IIi size of the paper used as the transfer material, the condition of the original, development due to environmental changes, and changes in charging characteristics. In response to such IS, the present invention provides an image forming apparatus in which a good cleaning effect is always obtained with an appropriate amount of toner, and which contributes to obtaining high-quality images. The purpose is to

(2) Structure of the invention (technical means for solving the problem, its effect) In order to achieve the above object, the present invention removes the residual toner remaining on the surface of the carrier after transfer with a cleaning blade, and removes the residual toner from the non-image area. An image forming apparatus in which toner is deposited in a black belt shape and supplied to a cleaning blade, comprising means for controlling the amount of the black belt toner depending on the type of transfer material and/or copying state. It is characterized by:

With this configuration, cleaning failures due to insufficient toner being supplied to the edge of the cleaning blade that contacts the image carrier! This method is effective in maintaining the image quality because it is possible to always carry out stable and good cleaning without causing damage to the carrier or contamination of the transfer material or various parts in the image forming apparatus due to excess toner.

(Description of Examples) First, an experimental example for exploring a suitable form of black belt formation will be described.

Table 1 below shows the black band formation and the number of copies made on Japanese paper in a normal humidity environment when making multiple copies in a single continuous manner, that is, after copying one sheet, pausing for a few seconds, and then copying another sheet. This study examines the relationship between

In the table, 0 indicates good condition and × indicates problem. In particular, the compensation sphere on the right side of the dotted line is an area where poor cleaning occurs due to lack of black band toner, and the area to the left of the dashed line is an area where toner is excessive.
This is an area where there is a high possibility that toner will fall into the transfer and WI transport area (the above instructions are the same in the following tables).

Table 2 shows the results of experiments conducted under the same conditions as in the above table using paper produced in Northern Europe.

Table 2 Table 1 Since the paper is made overseas, there is a lot of paper dust, and from the positions of the dotted line and the jI line, it can be seen that a larger amount of black belt toner is required than in the case of the above-mentioned cloth.

Table 3 shows the results of an experiment conducted in a single continuous manner using paper produced in one country in a low humidity environment where poor cleaning is likely to occur.

Table 3 From this table, the copy density decreases in a low humidity environment, and there is a tendency for the density to decrease in the case of single continuous copying.
It can be seen that it is necessary to further increase the spread of the black band toner than in the case of Table 2 above.

Table 4 shows the results when A4 size paper was used under the same conditions as in Table 1 above.

Table 4 You can get a relaxing effect in minutes.

Table 5 shows the results of an experiment using overseas-produced paper in a low-humidity environment.

Table 5 According to this table, the required amount of black belt toner is A4 size 1
The required amount of sheets will be less than that of 1/2 A3 size sheet. Comparing this with the case of A3 size in Table 1 above, since the paper size is half, there is idle rotation between the sheets, and even if a large amount of toner comes from the image area, the burden on the cleaning blade is less. As you can see from the table, when printing overseas transfer paper with a lot of paper dust in a low humidity environment, the copy density is low, and the toner is even blacker than in Table 3. It is necessary to increase the amount of

Table 6 shows an experimental example in which continuous copying was performed using domestically produced paper in a normal humidity environment.

Table 6 In this case, the humidity is normal, the copy density is high, and the paper is made in Japan, so there is less paper dust, and the number of rotations of the photoreceptor is lower than in the above 6 examples due to continuous copying, so the amount of toner is also As shown by the dotted line and chain line in the figure, it can be seen that only a small amount is required.

Table 7 shows the results of a paper feeding experiment conducted under the same conditions as in Table 4 except that the transfer paper size was changed from A3 to A4.

Table 7 From the table above, it is clear that by making the transfer paper smaller, the 5th
It can be seen from the movement of the positions of the dotted and dashed lines in the table and the table above that the required amount of black band toner can be reduced.

Furthermore, in high humidity conditions, image blurring occurs due to the surface resistance of the photoreceptor becoming low due to moisture-absorbing components adhering to it.
It has also been found that the problem can be improved by increasing the amount of black band toner when the humidity is high.

m1IA shows an embodiment for controlling the amount of black band toner depending on the state.

This method consists of a copy status detection section and a black belt control generation section, and when starting copying, the A
It is assumed that the coefficient of the amount of black band toner is experimentally set in advance based on the factor ``.

Depending on the type of paper, the amount of paper dust, and the amount of talc, the toner acid should be increased for those with a large amount of these.

Depending on the size of the paper, longer paper requires more toner, l
] For narrow, set the black belt 1] to be narrow.

Furthermore, if necessary, an appropriate amount of toner is applied to non-sheet passing areas.

Copy mode factors include single copying, continuous copying, and if the latter, how many copies are being made; that is, by detecting the number of copies and the number of rotations of the photoreceptor, the coefficient of the amount of black belt toner is set in proportion to these. decide.

Next, the amount of toner reaching the cleaning device is detected, and a collected toner coefficient is set in inverse proportion to this amount. It is possible, for example, to detect the amount of toner developed by toner consumption or toner replenishment.

Another method is to detect the toner density on the photoreceptor surface or on the remaining toner after transfer. These may be used as the recovered toner coefficients by simply detecting the image ratio of the original by AE or I reading the image of a digital copying machine.

Furthermore, the boundary coefficient is determined based on temperature, humidity, atmospheric pressure, etc. For example, when the humidity is low, the coefficient is determined so that the amount of toner adhesion increases as described above.

Once each coefficient is calculated based on the above factors, it is input to the black belt toner amount calculation means, and the black belt toner amount is determined for each coefficient by a predetermined function. The toner amount control means determines (1) the black band or the number of black band formations per copy or per photoreceptor rotation number.

Next, as a black band generating means, a desired black band is formed by controlling blinking of blank exposure and its time, or by changing the DC component of the developing bias.

Next, an experimental example regarding the formation of a black band due to the difference in type and size of transfer paper among the above-mentioned factors will be explained with reference to FIGS. 2 and 3.

The paper type selection means determines the required amount of toner according to the amount of paper powder and components such as talc and silica. For example, in FIG. 2, overseas produced paper adheres more toner than domestically produced paper A.

An appropriate toner amount ratio shall be determined experimentally depending on the various types of paper used.

As shown in Figure 2, domestically produced paper A, B and overseas produced paper,
The paper coefficients of H were determined as 1.5.3.3.6, respectively.

Next, the paper size selection means causes a larger amount of toner to adhere to a longer paper than to a shorter paper.

As shown in FIG. 2, A4, B4. The ratio of required toner for each A5 size was 0.4.0.7.1.0.

The table below is an example of calculation for transfer paper of paper type B and size A3.

No. 8 For cover type B, the minimum amount of toner that does not cause toner leakage after every 6 copies of the black belt is the first.
It can be seen from the table that it is 3II11, the paper coefficient is 3 from FIG. 2, and the paper size is determined to be 1 from FIG.

Next, the black belt toner amount calculation means determines the black belt to be medium 3II11 from each coefficient of paper type and paper size.

Next, the black band toner amount control means forms a black band with a width of 3+a+i once every six copies, for example, by controlling blank exposure.

Experimental example 2 in Table 8 is an example in which one paper type is E and the paper size is A3. At this time, the paper coefficient is 6 for the paper type and 1 for the paper size, and the amount of black band toner is The calculation result is 6
It is mm.

In Experimental Example 3 in the same table, the paper type is B and the paper size is A4, so the paper coefficients are 3 and 0.4, respectively, and the calculation result of the black band toner amount is 1.2+u+.

The experimental examples using one paper type and paper size have been described above, but it is also possible to determine the amount of black belt toner based on only one of these factors, and also to determine the development and charging characteristics due to the environmental changes mentioned above. It is easy to understand that the appropriate amount of toner can be determined by taking into consideration at least one of factors such as changes and the state of the document.

(3) As described in the detailed description of the invention, according to the second invention, toner is supplied to the cleaning blade edge of the cleaning device to smooth the cleaning action by adhering the toner to the non-image area. By making it possible to appropriately control the amount of toner supplied to the edge of the cleaning blade, it prevents cleaning failures due to insufficient toner and contamination of the transfer material and various parts within the device due to excess toner, and provides a constant and stable flow of toner. Since a good leaning function can be maintained, it greatly contributes to obtaining high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the invention, FIG. 2 is a block diagram showing another embodiment of the invention, and FIG. 3 is a schematic side view showing the configuration of an image forming apparatus suitable for applying the invention. It is a diagram. 1. Photoreceptor, 4φ-.-forming charger, 5. Blank exposure lamp, 7. Exposure section, lO. Developing device, 1
2.φ・Transfer charger, 14φ.・Cleaning blade.

Claims (6)

[Claims] (1) In an image forming apparatus that removes residual toner remaining on the surface of the image carrier after transfer with a cleaning blade, and also applies toner in a black band shape to a non-image area and supplies it to the cleaning blade, An image forming apparatus comprising means for controlling the amount of the black band toner according to the type of transfer material and/or the copying state. (2) The image forming apparatus according to claim 1, wherein the means for controlling the amount of the black belt-shaped toner is means for controlling at least one of the number of times the toner is formed, the width, and the density. (3) The image forming apparatus according to claim 1 or 2, wherein the means for controlling the amount of the black belt-shaped toner is means for controlling at least one of the type and length of the transfer material. . (4) The means for controlling the amount of black band toner is a means for calculating the type of transfer material and the cumulative number of sheets to be passed, and controlling the amount of toner depending on the type of transfer material according to the result. The image forming apparatus according to any one of the ranges 1 and 2. (5) The means for controlling the amount of black belt-shaped toner includes means for calculating the length of the transfer material and the cumulative number of sheets to be passed, and according to the results, the means for controlling the amount of toner according to the length and number of sheets of the transfer material. An image forming apparatus according to claim 1 or 2. (6) A patent claim in which the means for controlling the amount of black belt-like toner is a means for controlling the amount of toner according to the length and type of the transfer material, comprising a calculation means for integrating the type and length of the transfer material and the number of both sheets. The image forming apparatus according to any one of the ranges 1 and 2.