JPH07219318A - Electrophotographic recording device - Google Patents

Abstract

(57) [Summary] [Object] To prevent a problem caused by an increase in the amount of toner on a developing roller that occurs over time in an electrophotographic recording apparatus. [Structure] The amount of toner from a toner supply unit is transferred to a developing roller 3 while being regulated by a metal blade 4,
In the electrophotographic recording apparatus that further transfers the image to the intermediate roller 2 and then develops the image on the photoconductor 1 by the toner on the intermediate roller 2, the image is transferred to the developing roller 3 when the preset number of recorded images is reached. Bias adjusting means 6 for changing the applied bias voltage is provided so that an appropriate amount of toner can always be transferred and attached to the developing roller 3 and the intermediate roller 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording device such as an electrophotographic copying machine or printer, and more particularly to a developing device section thereof.

[0002]

2. Description of the Related Art FIG. 4 is a schematic view showing a developing device portion of a conventional electrophotographic recording apparatus. Toner carrier means 2 (second toner carrier means) using an elastic member is in contact with the roll-shaped photoreceptor 1, and toner carrier means 3 (first toner carrier means) is attached to the toner carrier means 2. Touching. Further, a blade-shaped toner amount regulating member 4 made of metal is provided adjacent to the toner conveying means 3. Further, the intermediate roller bias voltage V _M is applied to the toner conveying means 2, and the developing roller bias voltage V _R is applied to the toner amount regulating member 4. In the following, the toner conveying means 2 will be referred to as an intermediate roller, the toner conveying means 3 will be referred to as a developing roller, and the toner amount regulating member 4 will be referred to as a metal blade.

By the way, in the one-component magnetic development system, the metal blade 4 has two roles of thinning the toner and triboelectric charging. The toner charged by the metal blade 4 and adhered onto the developing roller 3 is used. Is the intermediate roller 2
By applying different biases to the developing roller 3 and the intermediate roller 2 in a state of being in contact with the intermediate roller 2, the intermediate roller 2 and the intermediate roller 2 are moved onto the photosensitive member 1.

Incidentally, the technology relating to this type of developing device is disclosed in, for example, Japanese Patent Laid-Open No. 63-202770 and Japanese Patent Laid-Open No. 63-202.
226676, JP-A-1-37572, JP-A-1-37
There are 573 etc.

[0005]

However, the above-mentioned one-component magnetic developing system has a problem that the amount of toner on the developing roller increases with time. That is, the amount of toner on the developing roller and the number of copies are in the relationship shown in FIG. 5 (the measurement shown here is a value measured after the intermediate roller is removed and after idling for 30 seconds with the bias end applied. ), The amount of toner on the developing roller increases as copying (recording formation) is continued, and is saturated at about 40,000 sheets. The value after saturation is about 0.70 mg / cm ^2, which is the initial value of 0.35 mg.
The value is twice as large as that of / cm ² . The problems that may be caused by the increase in the amount of toner on the developing roller over time include excessive density, thick characters, background stains, and an increase in toner consumption speed.

Therefore, an object of the present invention is to provide an electrophotographic recording apparatus capable of avoiding the problem caused by the increase in the amount of toner on the developing roller which occurs over time.

[0007]

In order to achieve the above object, the present invention transfers and adheres toner to a first toner conveying means while regulating the amount of toner from a toner supply portion by a toner amount regulating means. In the electrophotographic recording apparatus for further developing the image on the photoconductor by the toner on the second toner transporting means after the toner is transferred to the second toner transporting means. Bias adjusting means for changing the bias voltage applied to the first toner conveying means is provided.

Further, the number of recorded sheets according to the above setting can be the number set at the time of delivery of the apparatus according to the frequency of use by the user.

Further, the first object is to regulate the amount of toner from the toner supply section by the toner amount regulating means.
In an electrophotographic recording apparatus for developing and developing an image on a photoconductor by the toner on the second toner transporting means after transferring and adhering to the second toner transporting means. This can also be achieved by providing linear velocity changing means for changing the linear velocity ratio of the first toner carrying means to the second toner carrying means when the set number of recording sheets is reached.

The change of the linear velocity ratio can be executed when the number of sheets set at the time of delivery of the apparatus is reached according to the frequency of use by the user.

[0011]

According to the above means, the first predicted over time
The control is performed such that the bias value applied to the first toner carrying unit (developing roller) becomes smaller in response to the increase in the amount of toner on the toner carrying unit (developing roller). As a result, a proper amount of toner is always transferred and adhered to the second toner conveying means (intermediate roller) and the photoconductor, and a stable recorded image can be obtained.

At this time, by setting the number of output sheets according to the frequency of use of the user, the increasing curve of the toner amount is corrected according to the frequency of use of the user, and a stable recorded image can be obtained.

Instead of controlling the bias value applied to the first toner transporting means (developing roller), the first toner transporting means (developing roller) can be controlled in response to an increase in the amount of toner on the first toner transporting means (developing roller). By reducing the linear velocity of the first toner conveying means (developing roller), an appropriate amount of toner is always transferred and adhered to the second toner conveying means (intermediate roller) and the photoconductor, and a stable recorded image is obtained. You can

Further, the linear velocity ratio is changed when the number of sheets set according to the frequency of use by the user at the time of delivery of the apparatus is changed to increase the amount of toner on the first toner conveying means (developing roller). Can be corrected according to the frequency of use,
Since the linear velocity can be changed appropriately, it is possible to always obtain a stable recorded image.

[0015]

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

FIG. 1 is a schematic diagram showing a developing device portion of an electrophotographic recording apparatus according to the present invention. In FIG. 1, FIG.
The same reference numerals are used for the same elements as those, so that the duplicate description will be omitted below.

The present invention is characterized in that the bias adjusting means 6 is provided between the metal blade 4 and the power source 5 which outputs the developing roller bias voltage V _R. Bias adjusting means 6
The bias voltage V _R applied to the metal blade 4 in accordance with the amount of toner on the developing roller 3, which is predicted from the number of copies
Has the function of changing.

FIG. 2 shows the relationship between the amount of toner on the intermediate roller 2 and the developing roller bias voltage V _R (the amount of toner on the intermediate roller 2 with respect to the developing bias of the amount of toner on the developing roller 3). At this time, the bias applied to the intermediate roller 2 is constant.

Here, the critical value of the toner amount on the developing roller 3 is, for example, 0.55 mg / cm ² and 0.70 mg / cm 2.
Assuming ² (saturation value), these values reach 15,000 sheets and 40000 sheets, respectively, as shown in FIG.
It is the time when 0 sheets are copied. Assuming that the amount of toner on the intermediate roller 2 required to transfer a sufficient amount of toner to the photoconductor 1 is 0.80 mg / cm ² , the appropriate value of the bias applied to the developing roller 3 is on the developing roller 3. The values of V _R1 , V _R2 , and V _R3 are in order from the one with the smallest toner amount.

Therefore, the initial developing roller bias value is set to V _R1, and after copying 15,000 sheets, it is automatically changed to V _R2 . Furthermore, the number of copies is 40,000.
After reaching 0 sheets, it is automatically changed to _VR3 . By such control, it becomes possible to prevent the transfer of the toner more than necessary onto the photoconductor 1 and eliminate the cause of the abnormal image.

Since the solid line characteristic in FIG. 5 is obtained when copying is performed almost continuously, the characteristic shown by the broken line in FIG. 5 is obtained when the frequency of use by the user is low. Therefore, the critical point for changing the bias depends on the frequency of use by the user. Therefore, if a value corresponding to the frequency of use by the user is input at the time of delivery of the recording apparatus and the bias is automatically changed when the value is reached, more toner than necessary is transferred onto the photoconductor 1. It can be prevented, and the cause of the abnormal image can be eliminated.

Further, the driving of the developing roller 3 must be independent and the number of rotations should be constant. The critical value of the toner amount of the developing roller 3 for changing the developing roller bias is set to 0.
55 mg / cm ² and 0.70 mg / cm ² (saturation value)
Assuming that, the number of copies reaching these values is 15,000 and 40,000, respectively. FIG. 3 shows the toner amount characteristic on the intermediate roller 2 with respect to the linear velocity of the developing roller for each toner amount on the developing roller 3. However, the linear velocity of the intermediate roller 2 is constant.

The amount of toner on the intermediate roller 2 required to transfer a sufficient amount of toner to the photoconductor 1 is 0.80 mg / c.
Assuming that m ^2, and the proper value of the linear velocity of the developing roller 3 becomes V _R1, V _R2, V _R3 in order of a small amount of toner on the developing roller 3. Therefore, the initial value of the developing roller linear velocity is set to V _R1 and is automatically set to V _R2 after completion of copying 15,000 sheets. Furthermore, 40,00
After reaching 0 sheets, it is automatically changed to _VR3 . By such control, it is possible to prevent an excessive amount of toner from being transferred onto the photoconductor 1, and it is possible to eliminate the cause of the abnormal image.

Further, it is also possible to input a critical number of sheets according to the frequency of use by the user at the time of delivery of the recording apparatus and automatically change the developing roller linear velocity when the critical number is reached.
By such control, too much toner can be prevented from transferring onto the photoconductor 1 and the cause of the abnormal image can be eliminated.

[0025]

Since the present invention is configured as described above, it has the following effects. In the electrophotographic recording apparatus of claim 1, since the bias adjusting means for changing the bias voltage applied to the first toner conveying means when the preset number of recording sheets is reached is provided, the intermediate roller and the photoconductor are provided. On the other hand, a proper amount of toner is always transferred and adhered, and a stable recorded image can be obtained.

In the electrophotographic recording apparatus of claim 2,
By setting the number of recorded sheets according to the above setting at the time of delivery of the apparatus according to the frequency of use of the user, the increase curve of the toner amount is corrected according to the frequency of use of the user, and a stable recorded image can be obtained. .

In the electrophotographic recording apparatus of claim 3,
Since the linear velocity changing means for changing the linear velocity ratio of the first toner conveying means to the second toner conveying means is provided when the preset number of recorded sheets is reached, an appropriate amount of toner is always supplied to the second toner conveying means. A stable recorded image can be obtained by being transferred and attached to the conveying means and the photoconductor.

In the electrophotographic recording apparatus of claim 4,
The change of the linear velocity ratio is executed when the number of sheets set at the time of delivery of the apparatus is reached according to the frequency of use of the user. It is possible to correct it at the same time, and it is possible to always obtain a stable recorded image.

[Brief description of drawings]

FIG. 1 is a schematic view showing a developing device portion of an electrophotographic recording device according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a toner amount on an intermediate roller and a developing roller bias voltage V _R.

FIG. 3 is a characteristic diagram showing the relationship between the amount of toner on the intermediate roller and the linear velocity of the developing roller.

FIG. 4 is a schematic view showing a developing device portion of a conventional electrophotographic recording device.

FIG. 5 is a characteristic diagram showing the relationship between the amount of toner on the developing roller and the number of copies.

[Explanation of symbols]

1 photoreceptor 2 second conveying means (intermediate roller) 3 first conveying means (developing roller) 4 toner amount regulating member (metal blades) 5 Power 6 bias adjustment means V _R developing roller bias voltage V _M intermediate roller Bias voltage

Claims (4)

[Claims] 1. A toner amount regulating means regulates the amount of toner from a toner supply portion, transfers and attaches the toner to a first toner conveying means, and further transfers the toner to a second toner conveying means, and then the second toner conveying means. In an electrophotographic recording device for developing an image on a photoconductor by the toner on the toner conveying means of
An electrophotographic recording apparatus comprising: a bias adjusting unit for changing a bias voltage applied to the first toner conveying unit when a preset number of recording sheets is reached. 2. The electrophotographic recording apparatus according to claim 1, wherein the number of recorded sheets according to the setting is a number set at the time of delivery of the apparatus according to a frequency of use by a user. 3. The toner amount from the toner supply section is regulated by a toner amount regulation means to be transferred and adhered to the first toner carrying means, and further transferred to the second toner carrying means, and then to the second toner carrying means. In an electrophotographic recording device for developing an image on a photoconductor by the toner on the toner conveying means of
An electrophotographic recording apparatus, comprising: a linear velocity changing means for varying a linear velocity ratio of the first toner carrying means to the second toner carrying means when a preset number of printed sheets is reached. 4. The electrophotographic recording apparatus according to claim 3, wherein the change of the linear velocity ratio is executed when the number of sheets set at the time of delivery of the apparatus is reached according to the frequency of use by the user.