JPS5860756A - Transfer method - Google Patents

Abstract

PURPOSE:To increase the number of degrees of freedom for selection of a used transfer paper and eliminate the influence of the humidity and the moisture content to transfer a toner image stably with a high precision, by calculating and determining a transfer voltage in accordance with the time constant of the transfer paper. CONSTITUTION:A standard capacitor CS and resistance R1 and R2 which are connected to a lower carrying roller 5 are connected in series, and a time constant of a transfer paper 7 is detected through an impedance converter Zi or the like connected in parallel to the roller 5. On a basis of the time constant of the transfer paper 7 passing through an A/D converter, a CPU operates and determines a value corresponding to an optimum transfer voltage. This determined value is converted analogically to control a transfer corona current driving circuit 3, and a toner image of a photosensitive drum 1 is transferred to the transfer paper 7 with the optimum transfer voltage. By this constitution, the number of degrees of freedom for selection of the used transfer paper is increased, and the influence of the humidity and the moisture content is eliminated to transfer the image stably with a high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer method, and particularly to a method for transferring a toner image on an image carrier obtained by development onto a transfer paper.

In an electrophotographic device or an electrostatic recording device, an electrostatic image is formed on an image carrier such as a photoreceptor or dielectric by a predetermined process, and after this is developed with colored fine particles called toner, the toner is The image is reproduced by transferring it to transfer paper.

Transfer is usually performed by electric field generating means such as a rolling roller or a corona charger to which a voltage of opposite polarity to that of the toner image on the image carrier is applied. Electric charges applied by these electric field generating means from behind the transfer paper superimposed on the toner image cause the toner image to be attracted to the paper and transferred.

It is known that the rate at which a toner image on an image carrier is transferred to transfer paper, that is, the transfer efficiency, varies greatly depending on the electrical resistance of the paper. The electrical resistance of transfer paper naturally changes depending on the type of transfer paper, but it also changes depending on changes in humidity and water content, even for the same type of transfer paper. For this reason, Japanese Patent Application Laid-Open No. 50-19456 discloses a transfer method in which a high resistance is connected in series between a transfer roller and a transfer power source, and thereby humidity changes in transfer paper are automatically compensated for by applied voltage. It is shown. Although this method has the advantage of being simple in structure, it has the disadvantage that it is limited to roller transfer and cannot be applied to corona transfer. Also, q,? Opening/closing 5
Japanese Patent Application No. 5-28081 discloses a transfer method in which the volume and surface resistance of the transfer paper are detected and the influence of humidity or moisture content of the transfer paper is thereby removed. This method gives good results if the transfer paper used is specified.

7￥If the type or thickness of the paper changes, it may become uncontrollable and run out of control. Therefore, this method can be said to be a transfer method with less freedom in selecting transfer paper. moreover,
JP-A No. 54-96046 describes the electrostatic capacitance b of transfer paper.
A method of controlling the voltage to optimize the transfer rate by detecting ε is shown. This method works for any type and/or thickness of transfer paper.
Although it is possible to provide optimal transfer conditions within certain limits, it has the disadvantage that humidity and moisture content cannot be controlled.

An object of the present invention is to provide a stable transfer method with high precision and high rolling efficiency, which expands the degree of freedom in selecting the transfer paper to be used, and eliminates the effects of humidity and moisture content in the transfer paper.

The object of the present invention is achieved by detecting the time constant or time constant and capacitance of the transfer paper and calculating and controlling these to determine the optimum transfer voltage.

Hereinafter, the present invention will be explained with reference to the accompanying drawings.

Note that the transfer paper in the disclosure of this invention includes a sheet or film made of a material other than paper. FIG. 1 schematically shows an example of a device for carrying out the transfer method according to the invention.

A transfer corona charger 2 is arranged opposite to the surface of the rotating photoreceptor drum 10, and a corona power supply drive circuit 5 is connected to its wire electrode.

Between the surface of the photosensitive drum 1 and the transfer corona charger 2, there is a pair of conductive conveyance rollers 4 and 5 that rotate while being in pressure contact with each other.
The rolled γγ paper 7 is fed in while being guided by the guide plate 6. The transfer paper 7 is fed in synchronization with the formation of the toner image (on the surface of the photoreceptor drum 1), and is superimposed on the toner image under the corona charger 2.

The upper conveyance roller 4 is connected to the movable end of the switch SW, one fixed end SW1 of the switch SW is grounded, and the other fixed end SW2 is connected to the power supply V. It is connected to the. A standard capacitor CS and two impedance converters are connected in parallel to the lower conveyance roller 5, and two resistors and R2 are connected in series to the impedance converter Z. At the connection point between resistors R1 and R2, there is an A/
A D converter is connected, and the output from this is sent to the CPU
The input tables from the ROM and RAM are both subjected to arithmetic processing. The output from the CPU is D/
A converter f is input, and the transfer corona power supply drive circuit 5 is controlled by its output.

2 and 5 show a measurement circuit and a measurement principle in the case where the resistance of the conductive conveyance rollers 4 and 5 in the transfer device is constant and ignored. Here, Ox is the capacitance fli of the transfer paper 7, Rx is the resistance of the transfer paper 7, and Vx is the potential on both sides of the standard capacitor 〇s.

Now, assuming that Vx when time t is to is Vxo, Vx after Δ seconds will be Vxo+ΔVx. Of course, Δ
When t-ω, assuming that the resistance of the standard capacitor Cs is infinite and ideal, Vx = Vo. If this Vx, Cs iτ has a finite resistance value Rs, then Rs
and the resistance value Rx of the transfer paper.

Here, the electrostatic capacitance ficx of the transfer paper is determined by the following equation.

Cx = (,)cs Mountain... (1) Vx.

Similarly, the time constant τ of paper can be obtained by expanding the following equation.

10ΔVX = (VO-Vxo) (+ -e engineering)...
(2) Generally, it is well known that if the transfer system is fixed, the optimum transfer voltage VT for transfer efficiency is uniquely determined by the electrostatic capacitance Cx, resistance Rx, etc. of the transfer paper. Therefore, by finding Cx and ΔVx from each of the above equations and then finding τ, VT can be obtained.

At this time, the optimum transfer conditions τ and the related characteristics between Cx and vT due to differences in the structure of the transfer system may be determined as a subroutine.

FIG. 4 shows an automatic 1i for the transfer device shown in FIG.
An example of a U ffl program is shown. As shown in the figure, first confirm that the transfer paper 7 has reached the pair of conveyor rollers 4 and 5, and then the pair of conveyor rollers stops rotating 4 and 50 times]
Second, the switch SW is switched to SW2.

As a result, Vxo at time t0 is read, and Cx=
The calculation of F(VXO) is performed. If the results of this calculation are plotted, the results will be as shown in FIG. 5, for example. Then, Δ
After confirming that seconds have passed, set Δ to ΔVX after seconds.
Based on this, τ−F(ΔVx
) is calculated. If we convert the result of this calculation, we get
For example, as shown in FIG.

Then, from the thus obtained and Cx, V
The calculation of T=F(τ·CX) is performed, and the obtained optimum transfer voltage VT is applied to the corona charger 2 via the transfer corona power supply drive circuit 5. If the results of this calculation are plotted, the results will be as shown in FIG. 7, for example. After the optimum transfer electric power is applied to the corona charger 2, the copy density is checked, and if the copy density is insufficient, the paper characteristics may be affected by humidity in the top and bottom layers of the stacked transfer paper. Since there may be a difference, several sheets of transfer paper in the upper layer are discarded, the above routine is repeated, and if the copy density is sufficient, the optimum transfer voltage is fixed.

As described above, according to the present invention, it is possible to simultaneously perform control over changes in moisture content and humidity to obtain optimal transfer conditions, which were previously performed separately, and control over changes in paper quality. In addition to eliminating the influence of humidity and moisture content in the transfer paper, the degree of freedom in selecting the use of transfer paper can be greatly expanded.

The transfer method according to this one invention can also be applied to a roller rolling method, and can be modified in various other ways within the spirit of the invention as set forth in the claims.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the transfer method according to the present invention, FIG. 2 is a measurement circuit diagram of the apparatus shown in FIG. 1, and FIG. 5 is a diagram of the apparatus shown in FIG. 1. Figure 4 is a diagram for explaining the measurement principle for the apparatus shown in Figure 1. It is a figure which plots the example of the calculation result in a program. Cx...Capacitance of transfer paper Rx...Resistance of transfer paper τ...Time constant of transfer paper Cs...Standard capacitor ~ Sales Figure 5 Iku d Martyr 7 Figure

Claims (1)

[Scope of Claims] 1. A method for transferring a toner image on an image carrier obtained by development onto a transfer paper, which method detects a time constant of the transfer paper and calculates and controls the time constant to obtain an optimum image. A transfer method including determining a transfer voltage. 2. The transfer method according to claim 1, which includes detecting the capacitance of the transfer paper and the time constant and calculating and controlling them.