JPH04324478A - Destaticizer for transfer drum - Google Patents

Abstract

PURPOSE:To surely detect the residual potential quantity of a transfer drum after a transfer is completely performed in a short period and to control destaticizing conditions so as to always set a surface potential after destaticizing at zero V by providing an electrometer detecting the residual potential quantity of the transfer drum and a residual potential destaticizer, and changing a destaticizing quantity applied on the residual potential destaticizer according to the detection output of the electrometer. CONSTITUTION:The electrometer 3 is arranged on the upstream side of the transfer drum 1 and the destaticizer 4 is arranged on the downstream side of the transfer drum 1. The electrometer 3 detects the residual potential quantity on the transfer drum 1 at the time of the destaticizing, and the output of the detection is inputted into a CPU 6. Since a high voltage controller 5 is connected to the CPU 6, an output signal from the CPU 6 is inputted into the high voltage controller 5, and the controller 5 switches the DC component of a destaticizing charger corresponding to the residual potential quantity to a proper quantity with the inputted signal, outputs and supplies it to the destaticizer 4. Thus, the surface potential after the destaticizing is always controlled to zero V, so that, in the transfer of a toner image, performed next, the occurrence of a failure in the transfer can be prevented, and a high quality image can be obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention transfers a toner image formed on a photoreceptor such as a drum or belt onto a transfer drum by placing a transfer material on the transfer drum and rotating the transfer drum to transfer the toner image onto the photoreceptor. The present invention relates to a static eliminator for a transfer drum that is transported to a transfer drum for transfer.

0002

2. Description of the Related Art In conventional transfer devices, charges remain in the transfer drum after the transfer material is separated after completion of transfer. If this charge remains in the transfer drum when the next transfer is performed, there is a problem in that an abnormal image is generated due to the influence of this residual potential. Therefore, in order to remove this residual potential, chargers are arranged along the rotational direction of the transfer drum. There is an AC charger that is connected to apply a DC-biased AC voltage.

0003

[Problems to be Solved by the Invention] In the conventional static eliminator for a transfer drum as described above, (1) since the DC potential of the DC charger is not controllable, the transfer drum may be charged depending on the environmental aging or the presence or absence of a transfer material. There is a problem in that even if the amount of charge is different, the charge is not always removed reliably, and instead the surface potential is charged to exceed 0V, so that the surface potential after charge removal cannot always be set to 0V. (2) Since the AC of the AC charger has the property of erasing the potential of the toner and photoreceptor, it is easier to set the static elimination conditions than DC static elimination, but when performing static elimination using AC as a transfer material separation device, The setting conditions for the transfer material must be changed depending on the charging conditions of the transfer material in the transfer device, so even if the AC charger itself can be stabilized by its self-control, it will not work if the input, that is, the amount of charge on the transfer drum differs. Until then, static electricity cannot always be removed to 0V potential. Furthermore, AC static electricity removal requires long-term application and has the problem of not being able to cope with higher speed machines. (3) In particular, when using a multicolor developing device, the residual potential inside the transfer drum varies greatly depending on multiple copy modes such as black copy mode and full color mode. The residual potential is significantly different. Therefore, depending on each mode, AC,
Although the DC amount is set to an appropriate amount, the more the mode has a large residual potential, the less the charge on the transfer drum can be neutralized by AC and DC neutralization. In addition, the residual potential of the transfer drum tends to fluctuate greatly due to deterioration over time and environmental changes, and when transfer is performed multiple times as in full color mode, the difference in residual potential between areas with and without transfer paper on the transfer drum increases. I end up. Furthermore, since AC chargers emit a large amount of ozone, safety protection is also required. As mentioned above, it supports full color mode, and is compatible with AC, D, high-speed machines, high humidity, and aging.
C-static charge removal alone cannot completely remove the charge on the transfer drum, and the charge remains, making it impossible to reduce the surface potential to 0V. This residual potential tends to cause transfer defects such as so-called transfer dropouts, resulting in abnormal images. There was a problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional transfer drum static eliminator, and to eliminate static electricity by reliably detecting the amount of residual potential on the transfer drum after completion of transfer within a short period of time. In the next toner image transfer, the static elimination conditions are controlled so that the subsequent surface potential is always 0V.
To provide a static eliminator for a transfer drum that prevents the occurrence of transfer defects and always provides high quality images.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention detects the amount of residual potential on the transfer drum 1 in the transfer drum static eliminator as described above. This static eliminator for a transfer drum is equipped with an electrometer 3 and a residual potential static eliminator (hereinafter referred to as static eliminator) 4, and the amount of static electricity removed applied to the static eliminator 4 is changed according to the detection output thereof. A static eliminator 4 is provided downstream of the electrometer 3 on the circumference of the transfer drum 1, and an upper limit is set on the amount of static electricity applied to the static eliminator 4.

[0006]

[Operation] As described above, in this invention, the amount of residual potential on the transfer drum 1 after the transfer is completed is detected by the electrometer 3 provided on the transfer drum 1 for detecting the residual potential. The amount of charge removed is changed to an appropriate amount according to the detection output and applied to the charge remover 4, so that the surface potential of the transfer drum 1 after charge removal is always 0V.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. In the conventional transfer drum static eliminator as described above, the present invention is as shown in FIG.
Regarding the rotating direction of the transfer drum 1, on the opposite side of the transfer position T, an electrometer 3 is placed on the upstream side of the transfer drum 1, and a static eliminator 4 is placed on the downstream side. The electrometer 3 detects the amount of residual potential on the transfer drum 1 during static neutralization, and inputs its output to the CPU 6. Further, since the high voltage control device 5 is connected to the CPU 6, the output signal from the CPU 6 is transmitted to the high voltage control device 5.
According to the input signal, the DC component of the static eliminator charger is switched to an appropriate amount according to the amount of residual potential, and the output is supplied to the static eliminator 4. In the above configuration,
The transfer device is formed, for example, in the shape of a drum or belt.

After the rear end of the final transfer material wound around the transfer drum 1 of the present invention passes through the transfer charger 2, the voltage applied to the transfer charger 2 is turned off (FIG. 2, 22). Further, even after the rear end of the final transfer material passes through the transfer charger, the transfer drum 1 continues to rotate, and the transfer charger 2 is turned off.
After the detected position passes the electrometer 3, detection of the potential of the transfer drum 1 is started (23 in FIG. 2, 41 in FIG. 4). This potential detection starts according to another sequence control (not shown).
This is performed by a potential detection output start command. After detecting the potential, the time required for the voltage applied to the static eliminator 4 to be controlled is set in advance in the CPU 6, and when the detection output is input to the CPU 6, FIG. 3 and Equation 1

[Formula 1] y=a(x+c(n-1))+b (However, when n≧2 is 30V or less, y=b) y: Applied voltage of static eliminator 4 x: Detected potential of electrometer 3 a: Static elimination Slope b of detection potential x and applied voltage y to make the subsequent potential 0V: Discharge starting voltage of static eliminator 4 c: Control amount (correction coefficient) at the second and subsequent control times n: Number of cycles (However, after the second time, the detected potential will be 30 V or less.) According to the relationship shown in the figure, the control amount according to the detected output is controlled for a preset time t (Fig. 2 23 24
) is applied to the high voltage control device 5 with a delay. Further, while the detection output is being input to the CPU 6, an application start command is simultaneously issued from the high voltage control device 5 to the static eliminator 4. It has the same time difference as the control amount application, but is slightly longer. In this way, real-time control is performed on the detection output, and control can be performed so that the neutralization potential is uniform despite small potential fluctuations, such as differences in areas with and without transfer paper.

When the transfer drum 1 rotates once after the start of static elimination,
The device is turned off sequentially, but in this embodiment, the potential for one more round is detected, and if it is in the range of 0V to 30V, the high voltage control start signal is turned off and the static elimination charger 2 is turned off (Figure 4 52 53 5455 56). This is to turn off the static eliminator after confirming that the static electricity has been reliably removed, assuming that the static electricity cannot be removed sufficiently due to an unexpected buzzard. During the second and subsequent rounds of control, the control amount of the neutralization voltage [formula 1c] shown in FIG. 3 is multiplied by n and applied. Furthermore, the amount of static electricity removed applied to the static eliminator 4 is clamped with an upper limit as shown in FIG. In addition, if there is a region where a static elimination potential of 30V or more is detected after one rotation, one more rotation detection control operation shall be performed (
53 4546 47 48 50 51), and further, the static eliminating voltage is applied to the static eliminator 4 with the above-mentioned time delay (47 in FIG. 4). Also, when a static elimination potential of 30V or less is detected, a high voltage application start command is issued, but [
Since the control amount is 0 according to Equation 1], static electricity is not actually removed. In this way, when the electrometer 3 detects two cycles, the detected potential becomes 30V or less. Also, one round is 30
When a voltage below V is detected, the high voltage application start command is turned off.
F, and the potential detection start command is also turned off.

0010

[Effects of the Invention] This invention is as described above, and by providing an electrometer and a static eliminator on the transfer drum to detect the amount of residual potential on the transfer drum, the residual potential after static electricity removal on the transfer drum can be controlled by the environment. , the amount of static electricity applied to the static eliminator is changed depending on the amount of residual potential, so even if there is no transfer paper, even if there is no transfer paper, Even if the residual potential differs in the area, static electricity can be uniformly removed to 0V. In addition, since a static eliminator is installed downstream of the electrometer, the amount of static electricity removed by the static eliminator is controlled and applied in real time to an appropriate amount according to the residual potential, allowing fine static elimination and reducing the surface potential. Since the voltage is always reliably 0V, transfer defects due to the influence of residual potential are prevented, and a stable high-quality image can always be obtained. Furthermore, by controlling the amount of static electricity removed, there is no need to use an AC charger, and a DC charger can be easily used, which has the effect of reducing ozone generation and increasing safety.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the invention.

FIG. 2 is a timing chart diagram of transfer, electrometer, and static elimination same as above.

FIG. 3 is a static electricity removal amount graph showing the relationship between the electrometer detected potential and the static eliminator applied voltage.

FIG. 4 is a flowchart diagram same as the above.

[Explanation of symbols]

1 Transfer drum 2 Transfer charger 3　Electrometer 4 Residual potential static eliminator 5 High voltage control device 6 CPU

Claims (3)

[Claims] 1. A transfer material is conveyed to a transfer position facing a photoconductor by rotation of a transfer drum formed of a dielectric material, and an electric charge is applied to the transfer material conveyed to the transfer position via the transfer drum. After the toner image on the photoreceptor is transferred onto a transfer material and the transfer material is separated from the transfer drum, an electrometer is installed on the transfer drum to detect the amount of residual potential on the transfer drum. A static eliminator for a transfer drum, characterized in that a static eliminator is provided for a transfer drum, and the amount of static electricity removed applied to the residual potential static eliminator is changed according to the detection output thereof. 2. The static eliminator for a transfer drum according to claim 1, further comprising a residual potential static eliminator on the downstream side of the electrometer on the circumference of the transfer drum. 3. The static eliminator for a transfer drum according to claim 1, wherein an upper limit is set for the amount of static electricity removed applied to the residual potential static eliminator.