JPH04275580A - Powder toner transferring method - Google Patents

Abstract

PURPOSE:To make the transfer rate of toner constant regardless of environmental change or the difference of the transfer property of every transfer paper and especially to transfer conductive toner to a plain paper. CONSTITUTION:This method is a powder toner transferring method in which electrostatic transfer is performed by measuring the volume resistivity of the transfer paper or the moisture content of the transfer paper before electrostatic transfer, and heating and processing the transfer paper by controlling a heating and drying device for the transfer paper by suiting the measured value so that the volume resistivity value of the transfer paper becomes >=10<12>OMEGAcm in an electrostatic recording system in which a toner image obtained by developing an electrostatic image with powder toner after the electrostatic image is formed on the surface of an electrostatic image carrier is electrostatically transferred to the transfer paper.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer method for always maintaining constant toner image transfer properties of transfer paper used in electrophotographic copying machines and electrophotographic printers.

0002

[Prior Art] In the electrophotographic process, an electrostatic latent image created on a photoconductive photoreceptor is visualized with toner, and then electrostatically transferred to plain paper to make a copy. The transfer rate is greatly influenced by the electrical resistance of plain paper. When the electric resistance is low, the transfer charge does not effectively act on the toner, so sufficient transfer is not performed, resulting in poor image quality. On the other hand, when the electrical resistance of plain paper used as transfer paper is high, toner is sufficiently transferred and a clear image is obtained. This change in the electrical resistance value of the transfer paper is mainly due to changes in the moisture content of the transfer paper depending on the humidity in the environment.
Inside the copying machine, the case portion in which the transfer paper is placed is heated to prevent the transfer paper from absorbing moisture even if the humidity of the environment is high. However, this method is not sufficient when the humidity is higher than usual, such as during the rainy season. Furthermore, since the moisture content of the transfer paper changes, it is difficult to transfer the toner image at a constant transfer rate. For this reason, in the conventional method, there was a problem that the image quality changed significantly, and when an image was formed by overlapping toners of different colors as in color copying, the color balance was disrupted.

[0003] Such problems in transfer rate due to changes in the electrical resistance of plain paper are more serious in developing with conductive toner than in developing using electrically insulating toner that has an electrical charge. Sometimes the problem is even more important.

One of the attempts to solve such problems is
This can be seen in Japanese Patent Application Laid-Open No. 58-125074. In this case, a method is adopted in which the moisture content is reduced by heating the transfer paper immediately before transfer. The degree of heating is determined by detecting the humidity inside and outside the copying machine, and depending on this value, the speed of the transfer paper passing through a heating section installed just before the transfer section is varied to control the moisture content of the transfer paper. ing. The problem with the above attempt is that
Since the speed of the transfer paper passing through the heating section installed just before transfer is variable, if the transfer paper is present across the heating section and the transfer section, the process speed of the copying machine can be changed accordingly. It lies in the fact that it becomes necessary. Considering how to prevent this by providing enough extra space,
This time, the copying machine itself becomes unnecessarily large and becomes impractical. Furthermore, methods using humidity detection generally do not have high humidity measurement accuracy, and
The moisture absorption response speed of the transfer paper due to environmental humidity is slow, and the relationship with the moisture content of the transfer paper and the relationship with the electrical resistance value of the transfer paper cannot be expressed quantitatively. There is also the inherent problem that even if the toner image is heated and dehydrated, the toner image is not necessarily transferred at a constant transfer rate.

[0005] Also, JP-A-59-105667, JP-A-6
1-11772, JP-A-61-176963, JP-A-0
1-11279 and Japanese Patent Application Laid-Open No. 01-265282, the idea is to improve the transfer rate of toner images by detecting the moisture content of transfer paper or atmospheric humidity and adjusting the corona discharge output and transfer bias voltage. It is being However, even with these methods, there is no attempt to quantitatively stabilize the transfer rate, so variations in image density cannot be avoided.
In the case of color copying, changes in color balance may occur. Furthermore, in Japanese Patent Application Laid-Open No. 62-50782, it is considered to detect the electrical resistance of the transfer paper and control the output of the transfer corona in accordance with this, but it is difficult to control the output of the transfer corona alone. It is difficult to ensure a constant transfer rate in the operating atmosphere. Furthermore, Japanese Patent Application Publication No. 01-1357
In Publication No. 2, an attempt is made to detect the surface electrical resistance value of the transfer paper and change the distance between the transfer corona wire and the transfer paper in accordance with this, but this is also the same as the above-mentioned idea. It does not quantitatively manage the transcription rate.

[0006]

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems and provides a method for maintaining a constant toner transfer rate regardless of changes in the environment or differences in transferability between transfer papers. This is what I am trying to do. A further object of the invention is to
The purpose is to enable transfer to plain paper using conductive toner.

Another object of the present invention is to directly measure the volume resistivity of transfer paper, and if it is less than 1012 Ωcm, 1
It is possible to increase the volume resistivity of the transfer paper by controlling the amount of heat given to the transfer paper or the temperature of the heating member without changing the process speed to a target value of 0.012Ωcm or more, or to measure the volume resistivity by infrared moisture After measuring the moisture content of the transfer paper without contacting it with a meter and converting it into a volume resistivity value that is proportional to the moisture content, transfer is performed by controlling the amount of heat applied to the transfer paper or the temperature of the heating member. The object of the present invention is to provide a method for increasing the volume resistivity of paper.

[0008]

[Means for Solving the Problems] The present invention provides an electrostatic method for electrostatically transferring the toner image obtained by forming an electrostatic image on the surface of an electrostatic image carrier and then developing it with a powder toner onto a transfer paper. In the recording method, the volume resistivity of the transfer paper is measured before the electrostatic transfer, and the heat drying device for the transfer paper is controlled in synchronization with the measured value, so that the volume resistivity of the transfer paper is measured. value is 10
A powder toner transfer method characterized in that the transfer paper is heat-treated to have a resistance of 12 Ωcm or more and the electrostatic transfer is performed, and as the invention of claim 2, the powder toner is transferred to the transfer paper using an infrared moisture meter before the electrostatic transfer. Measure the moisture content of the transfer paper, control the heat drying device for the transfer paper in synchronization with the measured value, heat-treat the transfer paper so that the volume resistivity value of the transfer paper becomes 1012 Ωcm or more, and perform the above-mentioned electrostatic transfer. The present invention relates to a powder toner transfer method characterized by:

As a method for forming an electrostatic image on the surface of an electrostatic image carrier according to the present invention, first, light is applied to an electrostatic image carrier such as an inorganic photoreceptor such as a Se-based or a-silicon-based photoreceptor, or an organic photoreceptor. After uniformly distributing the electric charge by charging it using corona discharge or the like without exposing it to light, image information is exposed to form an electrostatic image. Thereafter, powder toner is selectively attached to the electrostatic image by the charge possessed by the electrostatic image or the electric field formed by the electrostatic image, and the image is developed. Powder toner is made by dispersing dyes, pigments, magnetic powder, etc. in binder resin in order to visualize electrostatic images, and has a volume-based average particle diameter of several μm to 20 μm.
It is a fine particle of about m. Powder toner can be roughly classified into insulating toner and conductive toner based on its volume resistivity, and the powder toner that can be used in the present invention may be either an insulating toner or a conductive toner. It is particularly effective in development using conductive toner of 1012 Ωcm or less.

The most common method for electrostatically transferring a toner image onto a transfer paper is to use corona discharge, but there is also a method in which a voltage is applied directly to a conductive member and contact is made from the back side of the transfer paper. There are a method of transferring, a method of coating the surface of the conductive member with a dielectric and transferring in the same manner, and any of these methods may be used.

Although the method for measuring the volume resistivity of the transfer paper is not particularly limited, for example, electrodes of a certain area are brought into close contact with the top and bottom of the transfer paper, and then a certain DC voltage is applied. There are two methods: one is to convert from the thickness and current value, the other is to place electrodes of a certain area on the top and bottom of the transfer paper and apply a certain AC voltage, and then calculate from the impedance and gain phase. Also good. Methods for measuring moisture content include, for example, resistance method, dielectric constant method, microwave method, optical method, etc., but optical method using infrared rays, which is non-contact and has a fast measurement speed, is suitable for the present invention. . The operating principle of an optical moisture measuring device (infrared moisture meter) utilizes the fact that energy at certain discrete wavelengths emitted in the near-infrared region is absorbed by water.

Next, there is no problem with the method of directly measuring the volume resistivity of the transfer paper, but in the case of the method of measuring the moisture content, this is converted into a volume resistivity value according to the graph shown in FIG. 2, for example. If the volume resistivity of the transfer paper measured in this way is 1012 Ωcm or more, there is no problem, but if the measured result is less than that, the transfer paper is heated by a heating member in synchronization with the value and the volume resistivity is Set the resistance value to the desired resistance value. Note that the optimum value of the volume resistivity of the transfer paper changes depending on the volume resistivity of the toner used, so after understanding the conditions, the target volume resistivity of the transfer paper is set. It has been experimentally determined that the volume resistivity of the transfer paper is a function of the moisture content of the transfer paper or the relative humidity of the environment, and does not depend on the temperature of the environment, so the volume resistivity of the transfer paper is used as the target resistance. The amount of heat required to raise the temperature can be specified. In this way, by always keeping the volume resistivity of the transfer paper constant, it is possible to always obtain a stable transfer rate. The present invention will be explained in detail below with reference to Examples.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an internal layout diagram of an electrophotographic printer, and is an embodiment specifically explaining the present invention. 1
1 is a photosensitive drum, around which a charging electrode 2, a laser writing section 3, a developing section 4, a transfer section 5 consisting of a transfer electrode and a separation electrode, and a cleaning section 6 are arranged. Reference numeral 7 is a transfer paper, which is housed in an airtight container 8 having an outlet that can be opened and closed. This storage container 8 includes an external heated air generating section 17.
An inlet 9 and an outlet 10 are provided for hot air at a relative humidity of about 40% or more, which is about 7 to 10° C. higher than the room temperature introduced from the room temperature. This heated air generating section is connected to a heat exchanger 19 from the upper part of the fixing section 18 via a heat pipe 15, thereby heating the air by utilizing heat radiation from the fixing device. The heated air generating section is preferably a Peltier element that partially cools the air and then heats it to produce high-temperature dry air. 11
is a guide member that guides the transfer paper to the photoreceptor drum,
A heating element 12 is attached to this guide member, and by inputting a temperature value detected by a temperature detection element 13 to a control section 14, the temperature of the guide section is adjusted to a control temperature. Therefore, the transfer paper passing through this section is heated to the set temperature by the heating guide section. An electrode roller 15, which is an electrode for measuring the electrical resistance of the transfer paper, is provided at the entrance of the guide section. The volume resistivity of the transfer paper from the storage box is measured here, and the value is sent to the control section 14, where it is determined whether it is less than or more than an arbitrary set value of 1012 Ωcm or more. If it is less than that, the heating temperature of the guide section is adjusted so that the set resistance value is reached within the time the transfer paper reaches the end of the guide section.

FIG. 2 shows the temperature at a certain heating temperature (1 in the figure).
00° C.), and shows the relationship between heating time and volume resistivity value for each transfer paper moisture content. Based on such a relationship diagram, the heating temperature at a given printer process speed can be incorporated into the program. Another volume resistivity measuring electrode 16 is provided at the exit of the guide section, that is, at a portion close to the photosensitive drum, and measures the resistance of the heated transfer paper whose moisture content has been lowered. The measured value here is fed back to the control unit 1 as feedback data to the guide unit heating control.
Sent to 4. Since it is preferable to adjust the heating temperature of the guide part in a short time, the heating element 12 attached to the guide part is a semiconductor heating element, and the guide member is made of a heat-resistant resin having a small heat capacity. In addition to this, a ceramic semiconductor heating element, an aluminum ribbon heating element, or the like may be used as the heating element. In addition, in reality, it is possible to dry the transfer paper container 8 to a certain high resistance value, so it is possible to achieve the threshold value even by using a normal heating wire heating element, and the temperature control width is not so large. Since it is not large, it is fully controllable. The guide section is constructed using a heat insulating material to prevent the influence of heat on the photoreceptor and developer. In this embodiment, the transfer paper storage container is heated and the heat-generating guide plate is used to dry the transfer paper.This is to dry the transfer paper mildly at the lowest possible temperature, but of course ,
It may be heated with a heated roller type, which also has the feature of being simpler in terms of mechanism. The present invention is not limited to this heating method.

[0015] In the above embodiment, an attempt was made using a resistance measuring electrode, but instead of the electrode, an infrared water content meter probe may be installed at that position. In this case,
The data from the probe is converted into a resistance value by an electrical resistance conversion program in the control section, and then heating current control of the guide section heating body is performed.

[0016]

According to the present invention, a constant toner image transfer rate can be achieved and images with excellent color balance can be continuously obtained during color copying. Furthermore, even in development using conductive toner, images with a high transfer rate were obtained without being affected by environmental humidity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the internal structural arrangement of an electrophotographic printer.

FIG. 2 is a graph showing the relationship between heating time and volume resistivity for transfer papers of various moisture contents.

[Explanation of symbols]

1 Photosensitive drum 2 Charging electrode 3 Laser writing section 4 Developing section 5 Transfer/separation electrode 6 Cleaning section 7 Transfer paper 8 Transfer paper storage container 9 Hot air inlet 10 Hot air outlet 11 Guide section 12 Guide section heating element 13 Temperature Detection element 14 Control section 15 Resistance measuring electrode roller 16 Second resistance measuring electrode roller 17 Heated air generating section 18 Fixing device 19 Heat pipe 20 Heat exchanger

Claims (2)

[Claims] 1. In an electrostatic recording method in which an electrostatic image is formed on the surface of an electrostatic image carrier and then developed with a powder toner, the resulting toner image is electrostatically transferred to a transfer paper. Measure the volume resistivity of the transfer paper beforehand, control the heat drying device for the transfer paper in synchronization with the value, and heat-treat the transfer paper so that the volume resistivity value of the transfer paper becomes 1012 Ωcm or more. A powder toner transfer method characterized by carrying out the electrostatic transfer described above. 2. In an electrostatic recording method in which an electrostatic image is formed on the surface of an electrostatic image carrier and then developed with a powder toner, the obtained toner image is electrostatically transferred to a transfer paper. Beforehand, measure the moisture content of the transfer paper using an infrared moisture meter, and control the heat drying device for the transfer paper in synchronization with that value, so that the transfer paper has a volume resistivity of 1012 Ωcm or more. A powder toner transfer method comprising heat-treating and electrostatically transferring the powder toner.