JPH0486780A - Electrostatic charge and destaticization device for image forming device - Google Patents

Abstract

PURPOSE:To prevent abnormal discharge from occurring and to always execute stable transfer and separation by impressing a voltage, which destaticizes a surface to be electrostatically charged, on an electrostatic charge device for destaticizing only while the electrostatic charged pulse of an electrostatic charge device for a pulse is suspended. CONSTITUTION:An electrostatic charger for transfer 2 is disposed by being faced to an image carrier 1. Besides, an electrostatic charger for separation 4 is disposed on the downstream side thereof. Then, a transfer part and a separation part are formed. Since a transfer material is apt to be attracted by the image carrier at the time of transfer, a separation bias having polarity which is reversed at the time of the transfer is impressed on the back surface of the transfer material by the charger 4 when the transfer material arrives at the separation part after the transfer. Then, the transfer material is destaticized and separated from the image carrier next by the elasticity of the transfer material itself. Then, it is carried to a fixing part. Thus, the danger of the abnormal discharge is reduced and the transfer and the separation are always stably executed.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) This invention provides a belt suitable for use in image forming apparatuses that utilize an electrostatic transfer process, such as electrostatic copying machines and printers. This invention relates to a static eliminator.

(Prior art and problems to be solved) In order to make this type of prior art easier to understand,
A well-known image forming apparatus will be described.

For example, a toner image electrostatically formed on the surface of an image carrier is electrostatically transferred to a transfer material such as paper, and immediately after that, the transfer material that tends to be attracted to the image carrier is removed from the image carrier. In a well-known image forming apparatus configured to forcibly separate the transfer material, a separation charger is disposed at the separation position, and this applies a bias voltage of opposite polarity to the back side of the transfer material to cause the transfer material to separate. A device configured to neutralize and eliminate the electric charge obtained during transfer to promote separation of the transfer material from the image bearing member is already in widespread use.

By the way, in such a configuration where a transfer charger is used for transfer and a separation charger is used for separation, the separation charger is usually located immediately downstream of the transfer charger (when viewed from the direction of travel of the transfer material). ), and since the transfer bias and separation bias are applied to both chargers almost simultaneously, the transfer current and separation current, which have opposite polarity to each other, interfere with each other. The reality is that higher output is required, and higher output is also required to increase the speed of image forming equipment.Therefore, there is a risk of increased costs and occurrence of abnormal discharge, so it is difficult to increase the speed of the equipment. It has become an obstacle.

FIG. 6 is a diagram schematically illustrating this, and shows that the toner image T formed on the surface of the image carrier traveling in the direction of arrow A is connected to the image carrier and the transfer charger TR. When reaching the opposing transfer site, the transfer material P is supplied to the transfer site at the same timing, and at this time, in the case shown in the figure,
A positive transfer bias is applied by the transfer charger TR, and the toner image on the image carrier T side is transferred to the transfer material, and due to the positive charge acquired by the transfer material due to the transfer bias applied at this time. The transfer material is attracted to the image carrier.

For this reason, a separation charger DE is provided at a position immediately after the transfer, and a bias voltage of the opposite polarity (in this case negative polarity) to that during transfer is applied to the transfer material that has arrived at this position, so that the transfer material is transferred. The positive charges acquired at the time of transfer are neutralized and removed, and the stiffness of the transfer material is used to separate it from the image carrier.

With this configuration, the positive discharge component of the transfer charger TR and the discharge component of the adjacent separation charger DE interfere with each other and neutralize and disappear, so that the image carrier In order to set the discharge current in the direction to the required value, a high-output power source is required to compensate for the above-mentioned disappearing charges.

The present invention has been made to deal with the situation described above, and is designed to prevent the bias voltages applied to both the transfer and separation chargers from influencing each other, and to reduce the components that are neutralized and disappear as much as possible. It is an object of the present invention to provide a transfer separation device that can reduce costs, prevent abnormal discharge from occurring, and always perform stable transfer separation.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides a charging device for static elimination disposed near a pulse charging device, and uses these to charge a surface to be charged. A charge eliminator that charges and then removes static electricity, characterized in that a voltage for removing static electricity from a surface to be charged is applied to the charging device for static electricity removal only while the charging pulse of the pulse charging device is paused. It is.

With this configuration, the charging device and the static eliminating device that are close to each other will not interfere with each other and wasteful discharge current will not be generated. By applying this to the image forming device, the device can be made smaller. This will reduce costs, reduce the risk of abnormal discharge, and provide significant improvements in functionality.

(Description of an Embodiment) FIG. 1 is a side view of a main part of an image forming apparatus according to an embodiment of the present invention, showing in particular the vicinity of a transfer and separation section, in which an image bearing member 1 facing an image carrier 1 traveling in the six directions of arrows is shown. A transfer charger 2 and a separation charger 4 are disposed downstream thereof, forming a transfer region and a separation region.

In the case shown in the figure, the photosensitive layer on the surface of the image carrier is an amorphous silicon photoconductor, which is positively charged by a primary charger (not shown), and after an image signal is applied to it and an electrostatic latent image is formed. , when a toner image formed by supplying negatively charged toner from a developing device (not shown) arrives at the transfer site, a transfer material P is supplied to the transfer site at the same timing, and a number of sheets are printed on the back surface of the toner image. A positive transfer bias of about 100 to several thousand volts is applied, and the toner image formed by negatively charged toner on the surface of the image carrier is transferred to the transfer material.

In addition to the above-mentioned primary charger, developer, etc., image signal applying means, cleaners, and other members necessary for image formation are of course arranged around the image carrier, but these are not included in this manual. Since they are not directly necessary for the invention, they are all omitted.

During transfer, the transfer material tends to be attracted to the image carrier, so when the transfer material arrives at the separation site after transfer, a separation bias with a polarity opposite to that during transfer is applied to the back surface of the transfer material by the separation charger 4. is applied to neutralize the transfer material, and then it is separated from the image carrier by the elasticity of the transfer material itself and conveyed to a fixing site (not shown).

In the illustrated apparatus, the transfer charger 2 includes a power source 3.
It is assumed that a pulsed positive polarity bias is applied to the separation charger 4 by the power source 5, and a negative polarity bias is applied to the separation charger 4 by the power supply 5.
As shown in , the phase is shifted in time, and the separation bias is not applied when the transfer is being performed.

Note that in FIG. 2, the amount of transfer current flowing into the transfer charger is adjusted by changing T r and V a, but since j+ has to be related to the frequency f and the waveform of the separation bias, (2) It is preferable to control.

In addition, regarding the pulse waveform of the voltage applied to the transfer charger and the transfer performance (presence of pulse traces and transfer defects),
If the speed of the transfer material is V2, the width of the opening of the transfer charger (length seen in the transfer material running direction) is dl, and the distance between the charging wire and the image carrier is d2, then Vp is larger, or When d, d2 are smaller, better results tend to be obtained when the transfer bias frequency f or ①a is larger.

The discharge current can be adjusted by adjusting the peak value V of the bias applied to the separation charger.

With the above configuration, the voltage applied to the separation charger has been increased from the conventional 7 Kv to 5 Kv, and in the case of transfer, the constant voltage control method has reduced the voltage that was required from 8 to 1 OKv to 6 to 7 Kv. It was confirmed that this effect can be obtained.

In this way, since transfer and separation can be performed with a lower voltage power supply than in the past, it is expected to reduce the cost of power supply production, reduce the amount of ozone generated, and reduce the risk of abnormal discharge, further increasing the speed of image forming equipment. It becomes possible to respond to

In the above device, we have explained the case where a rectangular wave is used as the pulse waveform of the transfer and separation bias. However, the biases applied to both chargers should not interfere with each other, and the applied voltages of opposite polarity should be discharged. From this point of view, for the separation bias shown in Fig. 3(e), it is possible to apply biases with various waveforms such as those shown in Fig. 3(a) to (d). It is easy to understand that it can be applied.

In this case, if a reverse polarity component as described above is included, if there is a slope in the rising and falling parts, consideration must be given to this part.

4 and 5 show only the waveforms of the transfer bias and separation bias showing another embodiment. In FIG. 4, twice the width t of the transfer pulse is one cycle of the AC waveform for separation. This coincides with the transfer bias, and at t2 when the transfer bias is stopped, a bias that includes a component of polarity opposite to the transfer bias of the AC separation bias is applied, so that the transfer bias and the separation bias do not interfere with each other. .

In FIG. 5, the frequencies of the transfer bias and separation bias are the same, but the pulse width t1 of the former and the pulse width of the latter are set to be different, or in this case also, during the application of the transfer bias, Separation bias components of opposite polarity are not applied at the same time.

(3) As described in detail, according to the present invention, a transfer charger,
In an image forming apparatus that uses a separation charger, a transfer bias and a separation bias component of opposite polarity are not applied at the same time, so the two biases interfere and cause transfer,
Since situations such as insufficient current for separation can be prevented as much as possible, related equipment such as power supplies can be simplified and the voltage can be lowered, leading to cost reductions and reducing the generation of ozone and Since the risk of abnormal discharge is reduced and transfer and separation can be carried out stably at all times, it is possible to increase the speed of this type of apparatus.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing the structure of an image forming apparatus according to an embodiment of the present invention, particularly the transfer and separation parts, and FIG. 2 shows the waveforms and temporal relationships of the transfer and separation biases applied to the same apparatus. Figure 3 is a diagram showing other bias waveforms applied to the transfer/separation charger, Figures 4 and 5 are diagrams showing other waveforms of the transfer/separation bias, and Figure 6 is a diagram showing the transfer charger. FIG. 3 is an explanatory diagram showing where the current of the separation charger and the current of the separation charger interfere with each other. DESCRIPTION OF SYMBOLS 1... Image carrier, 2... Transfer charger, 3... Open power supply, 4... Separation charger, 5... Open power supply, p...
・Transfer material. Figure 1 Figure 3 Figure 2 Figure 2

Claims (2)

[Claims] (1) In a charge eliminator in which a charging device for charge removal is disposed near a pulse charger, a surface to be charged is charged by these devices, and then the charge is removed, the charge is removed only during a pause in the charging pulse of the pulse charger. A charge eliminator that applies a voltage to remove static electricity from a surface to be charged. (2) A transfer material is brought into contact with the toner image electrostatically formed on the surface of the image carrier, a transfer bias is applied to the back surface of the transfer material to transfer the toner image to the transfer material, and then the back surface of the transfer material is transferred to the transfer material. In an image forming apparatus that separates a transfer material from an image carrier by applying a separation bias containing a polarity component opposite to the transfer bias, the transfer bias application means is a pulse charging device,
A charge eliminator in which a separation bias applying means is a separation charging device that applies a separation bias component having a polarity opposite to that of a transfer bias only during a pause in a charging pulse.