JPS599679A - Image formation device - Google Patents

Abstract

PURPOSE:To perform the destaticization and separation of a transferring material from an image carrier surface stably and easily, by detecting the surface potential of the image carrier surface after latent image formation, and calibrating and controlling the output of a transferring material destaticization and separation electrostatic charger to a proper output according to the detected value. CONSTITUTION:The transferring material P to which an image on a drum 1 is transferred by a transfer electrostatic charger 6 is discharged by the transfer material destaticization separation electrostatic charger 8 to the opposite polarity and separated from the surface of the drum 1 successively. A potential sensor 12 detects the surface potential of the surface 1 of the drum after latent image formation and its signal is inputted to an arithmetic circuit 14 to calculate a proper control value corresponding to the detected surface potential, controlling the transformer 81 of the separation electrostatic charger 8. Consequently, an impressed voltage is varied according to the image state of an original to perform the destaticization and separation of the transferring material P from the drum surface easily and stably, and variation in transfer efficiency is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the electrophotographic method, the electrostatic recording method, and other known appropriate principle techniques to create a static (or potential) latent image corresponding to image information to be copied or recorded on the surface of a latent image carrier. form an image, its m
The image is visualized as a toner image, and the toner image is transferred to the surface of a transfer material using a corona discharge transfer method, and the transfer material, which is electrostatically brought into close contact with the surface of the latent image carrier by this corona discharge transfer, is neutralized and latent. An image forming apparatus that obtains a copy or recorded material by separating it from the surface of an image carrier) = related.

Fig. 1 shows a very schematic configuration of an example of an image forming apparatus of the above type (1 is a secondary photocopying machine). is rotated in the direction of the arrow.

The drum surface of the drum 1 is uniformly charged positively or negatively by a charger 6 during its rotation. The image information to be copied or recorded is then exposed to light at an exposure station 4, thereby forming a still image corresponding to the turn of the exposure C2. Although the exposure device or mechanism is omitted in Figure 2, II
! Those that perform slit imaging exposure of the X draft image using a through-lens system, those that scan and expose with laser beams or X-rays, LE
A large number of devices are known, including those using D arrays and the like.

The electrostatic latent image on the drum surface is sequentially visualized as a toner image T while passing through the developing device 5 position.

Next, the toner image T passes through a transfer charger 6 and is fed between the charger 6 and the drum 1 from a paper feeding mechanism (not shown) in 161 rotations with the rotation of the drum 1. The image is transferred by corona discharge onto the two sides of the transfer material. 7 indicates a transfer material feeding guide. This corona discharge transfer is performed by applying a corona discharge period to the back surface of the transfer material P using a charger 6, and transferring the transfer material P to the drum 1.
This is efficiently achieved by bringing the toner image on the drum 1 t+'n 1ill into close contact with the surface of the transfer material P and by attracting the toner image on the drum 1 t+'n 1ill toward the surface of the transfer material P by electrostatic attraction. 61 is the transfer amount 'I! ! It is a trance of dexterity.

The transfer material P, which has passed through the transfer charger 6 position and is electrostatically in very strong contact with the drum 1 surface, is then charged with an electrostatic discharge separation charger 8 on its back side with a corona with a polarity opposite to that of the transfer corona. The static electricity is removed by receiving an AC corona, or a corona made by adding a heavy DC to an AC. Due to this static electricity removal, the static ridge-clamping force of the transfer material P against the first surface of the drum is weakened, and the transfer material P is naturally f. easily separated sequentially. 81fj: A transformer for static elimination separation charger.

The transfer material P separated from the surface of the drum 1 is sent to a fixing device (not shown in the figure) by a conveying means 9, where the transferred toner image on the surface is subjected to a predetermined process and then discharged outside the machine as a copy or recorded material. .

On the other hand, one side of the drum from which the transfer material P was separated is a charger 1 for static electricity removal.
At step 0, the electrical memory is removed and the transferred remaining toner image is electrically neutralized, and then the remaining toner image is removed at the cleaning device 11 to make the surface clean and used for repeated copying.

Such an electrostatic one-separation force type is realized by a balance between the reduction in absorbing force due to neutralization of the backside load of the transfer material P and the physical properties of the transfer material P itself (such as the stiffness of heavy 9 paper).

The adsorption force is reduced by static electricity removal and separation charging,
The appropriate value for reducing the adsorption force by the static elimination/separation charger differs depending on the surface potential on the drum.

Therefore, in the above-mentioned image forming apparatus, if the output (electrostatic elimination current) of the transfer material neutralization separation charger 8 is adjusted to a document with a lot of solidity such as a photograph, a non-image such as a text document (general document) will be generated. When copying a document with many copies, it may be difficult to separate the transfer material P from the surface of the drum, resulting in poor separation.

On the other hand, if the appearance is matched to a two-character original, etc., a so-called retransfer phenomenon occurs when copying a photographic original, and the transfer rate decreases, resulting in a decrease in image density and an uneven image. In addition, it is difficult to separate, and poor separation is also found.

As a result of investigating the phenomenon described above, it was found that the level (absolute value) of the surface potential based on the formation of a latent image on the image bearing member of the drum 1 is involved in the separability of the transfer material P.

That is, in the case of copying or recording image 1# with many solid black areas, the overall surface potential of the latent image carrier based on the formation of the m image becomes even worse.

If the direction of the transfer material neutralization/separation charger 8 is not adjusted accordingly, an overstatic discharge phenomenon will occur, and the transfer material P will be recharged and brought into close contact with the surface of the latent image carrier 1, resulting in a decrease in separation performance. Put it away. Also, due to the re-adhesion and excessive charge removal of the transfer material, the transfer material P
111! The transferred toner image of I is re-transferred and adhered to the side of the I-F region carrier 1, resulting in a lower transfer rate.

The graph in FIG. 2 is an example of a qualitative relationship graph between the surface potential image based on the latent image formation of the fTt image carrier and the appropriate voltage 11f of the transfer material P.

The present invention was made based on the above findings.

This eliminates the glaring drawbacks mentioned above. That is, the surface potential after the formation of a latent image on the surface of the image carrier a is detected by the potential sensor 12 (
(FIG. 6), and the output of the transfer material neutralization/separation charger 8 is calibrated and controlled to an appropriate value in accordance with the detected value.

In the example shown in FIG. 6, the potential sensor 12 detects the surface potential of one surface of a drum, which is an m-image carrier, after a latent image is formed.

The detection output of the sensor 12 is amplified by an amplifier 13.

The amplified signal No. 1g is inputted to the Vt calculation circuit 14. The arithmetic circuit 14 stores in advance relational data as shown in the graph of FIG. 2 as arithmetic data, and based on this, calculates an appropriate control value corresponding to the detected surface potential and controls the charger B for static elimination and separation of the transfer material. This is to control the transformer (81).

There is a time difference such that when the surface potential portion detected at this time reaches the separation portion, an appropriate value for the surface potential portion is applied to the static elimination separation charger 8. Therefore, the voltage applied to each tower is changed depending on the state of the image in the document. This is usually done during the close-up process.

In other words, regardless of the difference in the form of the image pattern to be copied or recorded, the static electricity removal and separation of the transfer material P from the latent image carrier 1 is always performed easily, stably, and smoothly, and the drum surface potential caused by the original can be detected in advance. do. Then, the voltage to be applied to the static electricity removal/separation device 8 is determined based on the integral value of the potential, and then a normal copying process is performed.

[Brief explanation of the drawing]

FIG. 1 is a very schematic configuration diagram of an example of an image forming apparatus, and FIG.
The figure shows the level of surface potential based on latent image formation on the m-image carrier,
FIG. 3 is a qualitative relationship graph of the appropriate separation electrostatic voltage of the transfer material. FIG. 3 is a configuration diagram of an example of an image forming apparatus to which the present invention is applied. Reference numeral 12 denotes a potential sensor, and reference numeral 8 denotes a transfer removal/awakening separation charger. 81 is trance. (Figure 2

Claims (1)

[Claims] (1) An electrostatic latent image is formed on the surface of the latent image carrier, the latent image is visualized as a toner image, the toner image is transferred to the transfer material surface by the corona discharge transfer method, and the m image is supported by this corona discharge transfer. The transfer material electrostatically brought into close contact with the surface of the body is removed from the surface of the latent image carrier by removing the charge using a charge eliminating charger. Or in an image forming apparatus that is designed to be in an easy-to-separate state. It is equipped with a means for detecting the surface potential of the 1fl carrier after the formation of the a-image, and depending on the detected value, the transfer material is removed for 1 minute.
The output of the electric wt device was calibrated and controlled to the appropriate output. Image forming apparatus #t0 characterized by