JPS63316074A - Transfer material separating device - Google Patents

Abstract

PURPOSE:To prevent the fault of separation of a transfer material and the occurrence of a retransfer, etc., caused by the quantity of images by altering the condition of transfer or separation according to a luminous signal generating time. CONSTITUTION:An electrostatic latent image is formed by projecting a laser beam 2 which is modulated in terms of image to execute scanning on a photosensitive layer on the surface of a photosensitive body 1 cylindrically formed, which rotates in a direction shown with an arrow. The latent image reaches the position of a developing unit 3 with the rotation of the photosensitive body 1 and it is developed by making toner supplied in the said position. In this case, the condition of either transfer or separation, at least, is altered according to the counting of an image exposing time in the specified length of the leading edge part of the image on the photosensitive body 1. Thus, a stable separation function can be always secured in spite of the amount of the image parts carried to the transfer material.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) This invention relates to a transfer material separation device suitable for use in image forming apparatuses such as laser beam printers, LED printers, and liquid crystal printers. It is.

(Prior Art and Problems to be Solved) The surface of the charged photosensitive layer is scanned with, for example, an image-modulated laser beam to form an electrostatic latent image, which is then developed and developed in the same manner as in a well-known electrostatic copying machine. A printer configured to form an image through processes such as transfer, separation, and fixation (
Since image forming apparatuses (image forming apparatuses) are capable of high-speed processing and are easy to obtain high-quality images, they are increasingly being used in computer terminal equipment and the like.

As mentioned above, in this type of printer, the steps after development are similar to those in an image forming apparatus that uses a normal electrostatic transfer process, and the transfer material is converted into a toner image at a transfer site equipped with a transfer charger. The toner image is electrostatically transferred to the transfer material by bringing them into contact with each other or in close proximity to each other, and applying a charge of opposite polarity to the toner to the transfer material.Then, at the separation site, the charge of the transfer material is removed by corona discharge of the same polarity as the toner. Conventionally, a device configured to neutralize static electricity and separate it from an image carrier is well known.

Printers that undergo the transfer and separation processes described above typically use paper as the transfer material, but the paper used as the transfer material comes in various thicknesses and thins, and their elasticity In addition, paper absorbs moisture, lowers its resistance, and tends to change its electrical characteristics, and it has not always been easy to perform good separation at all times depending on the differences in these properties.

For example, if paper with high elasticity or cardboard is used as a transfer material, it will easily separate from the image carrier due to its elasticity and its own weight if the charge applied during transfer is removed to some extent, but transfer paper that is thin and has low elasticity In this case, it becomes difficult to overcome the adsorption effect between the image carrier and the image carrier and separate the image carrier. Furthermore, if the resistance of the transfer paper decreases due to moisture absorption, charge leakage occurs, which inevitably causes a difference in separation conditions from when it is dry.

Furthermore, when there are only a few image areas formed on the transfer paper, the adsorption effect with the image carrier becomes strong, which leads to an insufficient amount of separation charge, which tends to cause poor separation.On the contrary, when there are many image areas, Conversely, there is a risk that white spots may occur due to retransfer due to excessive charge removal, leading to deterioration of image quality.

Therefore, there is a problem in that the latitude of the amount of charge applied to the separation charger for performing good separation becomes narrow.

The present invention has been made to deal with this situation, and is particularly designed to provide a transfer material that can be used in laser printers and the like, and which can always perform good separation regardless of the size of the image portion formed on the transfer material. The purpose is to provide a separation device.

(2) Structure of the invention (technical means for solving the problem, its operation) In order to achieve the above object, the present invention provides an image forming apparatus that converts an image signal into a light modulation signal to obtain an image. The present invention is characterized in that the image exposure time for a predetermined length of the image leading end of the member is counted, and at least one of the transfer and separation conditions is changed in response to the count.

With this configuration, a stable separation function can always be ensured regardless of the size of the image portion carried on the transfer material.

(Description of Embodiments) FIG. 2 is a schematic diagram of the main parts of a laser printer to which the present invention is applied, in which an image is modulated on a photosensitive layer on the surface of a cylindrical photoreceptor 1 that rotates in the direction of the arrow. The laser beam 2 is projected and scanned to form an electrostatic latent image.

As the photoreceptor rotates, the latent image reaches the position of the developing device 3, where toner is supplied and the latent image is visualized.

The visualized toner image further advances and reaches a transfer site having a transfer charger 5 in synchronization with the transfer material (not shown) supplied by the conveyance path 4, and the toner image is transferred from the photoreceptor to the transfer material. metastasizes to.

Next, the transfer material is separated from the photoreceptor by the action of the separation charger 6, and is fed to a fixing site (not shown) through a conveyance path 7.

In the present invention, such a printer is configured to change the transfer and/or separation conditions as described below.

FIG. 1 is a control block diagram showing an embodiment of the present invention, in which an image signal S is modulated by a modulator 10 and a laser 1
1, and the laser emits or dims the light accordingly to scan the surface of the photoreceptor and form a latent image thereon.

In response to this light emission, the counter 12 counts the number and adds it to the memory 13.

When image formation for, for example, 20 mm from the leading edge of the transfer material is completed, the corresponding contents of the memory 13 are corrected by the paper size signal Sp by the correction circuit 14 and transferred to the memory 16.

In this case, the count was set to 20 the number of light emissions in the first layer,
This is simply because the transfer material adhering to the photoconductor usually separates at its leading end, and then easily separates due to its own stiffness, weight, etc. , but is not particularly limited to 20 mm.

The contents of the memory 16 are input to the controller 15, and according to the count number, they are arithmetic-processed to become a preset appropriate DC component of the separated corona, and the output signal St is applied to the high-voltage transformer control circuit. As a result, a suitable transfer or separation corona is applied.

In the figure, the symbol R5Tl is a signal that resets the counter 12 and the memory 13, and the symbol R3T2 is a signal that resets the memory 16.

As shown in FIG. 3, the appropriate DC component of the corona discharge described above produces a solid black image, 5
% printed image and a solid self-portrait, determine the separation latitude of each as shown by the arrow, and determine the separated corona current.As shown in Figure 4, the value obtained from the laser emission count and the DC component of the optimal corona current are calculated. It is assumed that a relationship is determined and inputted, and the optimum separated corona current is determined in comparison with the count during image formation to determine the output St.

Although the above method controls the direct current component of the separated corona current, it is of course possible to change the exchange rate of the separated corona or the transfer corona current.

FIG. 5 shows the separation latitude obtained when the transfer corona current is increased by 20%, and the latitude is narrower than in the case described above.

In such a case, it is sufficient to reduce the transfer corona by 20% or turn it off at the counting part (the above-mentioned 20+u+ part) at the leading edge of the transfer material.

Although the present invention has been described above with respect to a laser printer, in this case, the present invention is applicable to both an image scanning method and a background method as image forming means, and the present invention is not limited to laser printers. LED that uses an image exposure method rather than a physical one
It is easy to understand that the present invention can also be applied to printers using liquid crystal shutters.

(3) As described in detail, the present invention provides an image forming apparatus that utilizes conversion of an image signal into a light modulation signal, in which the leading end portion of the transfer material has a suitable length range when viewed in the running direction of the transfer material. Since the transfer or separation conditions are changed according to the emission time of the optical signal representing the amount of the image, it is possible to prevent the occurrence of poor separation of the transfer material and retransfer due to the amount of the image as much as possible. In addition, stable separation can be performed at all times regardless of environmental changes or changes in the characteristics of the transfer material itself, which greatly contributes to obtaining high-quality images.

[Brief explanation of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention; FIG. 2 is a schematic side view of main parts of an image forming apparatus to which the present invention is applied; FIG. 3 is a diagram showing separation latitude of separated corona current; Figure 4 is a graph showing the relationship between the direct current component of the separated corona current and the number of counts, and Figure 5 is a graph showing the separation latitude when the transfer corona current is increased by 20%. l@Φ・Photosensitive L2-...Laser beam, 3...Developer, 5...Transfer charger, 6...Separation charger, 10-@
φ modulator, 11...-laser, 12φ・fist counter, 1
3.16---Memory, 14 Kushiken・? fHE circuit, 1
5... Yu controller, 17... High voltage transformer control circuit. Figure 1 Ji2 Figure 3 Figure 3 m-"elm + Io4's υ (1? 11 Figure 5

Claims (1)

[Claims] In an image forming apparatus that converts an image signal into an optically modulated signal, a transfer or an optical signal is generated in an appropriate length range of an image leading end portion of an image carrier that forms a latent image. A transfer material separation device comprising means for changing separation conditions.