JPH0229676A - Transfer device - Google Patents

Abstract

PURPOSE:To prevent the soil of the back face of transfer material by providing a toner receiving member between transfer material guide members and a transfer means in non-contact state with the transfer material and setting the potential of the toner receiving member equal to or lower than those of the transfer material guide members. CONSTITUTION:The toner receiving member 7 is provided, not in contact with the transfer material, between the transfer material guide members 8 and 9 guiding the transfer material to the surface of an image carrier and the transfer means, and the potential of said member 7 is equal to or lower than those of the transfer material guide members. Since the potential of the toner receiving member 7 is lower than those of the transfer material guide members 8 and 9, a larger amount of current generated by corona discharge flows in the toner receiving member than that flows in the guide members 8 and 9, the transfer current generated by transfer corona discharge, shown by arrows, flow into the toner receiving member 7 in large quantities, whereby much corona generated by transfer corona discharge and much floating and flying toner due to transfer corona discharge are led to the toner receiving member 7. Consequently, the toner never attaches to the transfer material guide members 8 and 9.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transfer device used in an image forming device such as an electrophotographic device or an electrostatic recording device, and particularly relates to a transfer device that prevents staining on the back side of a transfer material. Regarding a transfer device.

[Prior Art] Conventionally, in an image forming apparatus such as an electrophotographic apparatus, a toner image formed on an image carrier such as a photoreceptor is transferred onto a transfer material for use. For this transfer, transfer material guide member (
Hereinafter, it will be referred to as a transfer guide. ) is used to guide the transfer material to the transfer position, and apply corona discharge or the like with a polarity opposite to that of the toner from the back side of the transfer material. A metal member is used for the transfer guide in order to maintain rigidity. However, when the transfer guide is grounded, the transfer current escapes from the transfer guide through the transfer material at high temperatures, causing transfer defects.If the transfer guide is placed in a floating state, the transfer defects disappear, but the transfer current flowing into the transfer guide was charged to a high potential, thereby attracting scattered toner and toner on the image carrier, and this transfer guide stain caused stains on the transfer material.

In order to solve these problems, methods shown in FIGS. 4 and 5 have been proposed in the past. In Figure 4, the transfer guide is grounded via a low-voltage element (■), and because it is always maintained at a constant potential, it does not become a high potential and does not cause contamination, and the transfer current is low enough to cause transfer failure. There is no cramping. In Fig. 5, the transfer guide is grounded via a resistor R with a high resistance of 100 MΩ or more, and as in Fig. 4, it does not cause stains or transfer omissions.6 However, it is true that Figs. Although the configuration is good under normal usage conditions and usage environments (including high temperature and low humidity), a new problem arose when toner adhered to areas other than the portions of the image bearing member that are in contact with the transfer material. For example, the 6th
As shown in the figure, the transfer material P is smaller than the image width of the image carrier 1, and even though it is not transferred, it exists in a toner image, a solid portion of toner, or a portion B on the image carrier. This occurs particularly when copying is performed with the document pressure plate (not shown) opened, for example, when copying wood, books, and the like. As a countermeasure in this case, there is a method in which a light irradiation unit irradiates a non-image area on the image carrier with light depending on the size of the transfer material to remove the electric charge on the image carrier and prevent toner from adhering to the image carrier. However, if the machine is small, there may not be enough space to install this light irradiation means, or the light irradiation means may be omitted if the machine is to be manufactured at a low cost.

Under the various conditions described above, there is a solid image that is not transferred on the image carrier, and when copying continues, the toner in the area B in FIG. 6 scatters, and floating toner increases in the vicinity of the transfer device.

By keeping the transfer guide at a constant potential, it is possible to make it somewhat less likely to get dirty, but as the amount of floating toner increases, the transfer guide gradually becomes dirty. Naturally, the transfer guide portion corresponding to section B in FIG. 6 becomes dirty. (Section 0 in Fig. 7) When transferring a transfer material whose size increases the image width of the image carrier, toner stains at the tip of the transfer material guide adhere to the back side of the transfer material, and the back side becomes dirty. Hail!

Incidentally, by separating the transfer guide from the image carrier, contamination can be greatly reduced, but if the distance of the guide is too far, the adhesion of the transfer material P to the image carrier will decrease, and the transferability will also decrease, resulting in poor transfer. No image available. Therefore, it is not possible to increase the distance between the transfer guides.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned drawbacks, and its purpose is to provide a good transfer material that is inexpensive and has a simple structure that does not cause stains on the back side of the transfer material. A toner receiving member is provided between the guide member and the transfer means in a non-contact state with the transfer material, and the potential of the toner receiving member is set to be the same potential as the potential of the transfer material guiding member or lower than that. That is.

[Example] The details of the present invention will be explained below using specific examples with reference to the drawings.

FIG. 1 shows a first embodiment of the invention.

1 is a photosensitive drum which is an image bearing member; 2 is a developing device which converts an electrostatic latent image formed on the photosensitive drum 1 by a latent image forming means (not shown) into a visible image; and 11 and 12 are transfer materials. Registration upper and lower rollers 8, which are transfer material guiding members that guide the transfer material to the image carrier, are upper transfer guides, 9 are lower transfer guides, and 10 are transfer guides 8 and 9 that are fed out with timing. A low voltage element that maintains the potential, 7 a toner receiving member that collects toner floating or scattered near the transfer section, and 5 a transfer corona discharge unit that transfers the toner image on the image carrier onto a transfer material. , 6 is a charge eliminating needle that eliminates the charge on the back surface of the transfer material, and 4 is a conveying device that conveys the transfer material carrying the transferred toner image to a fixing device (not shown). A cleaner 3 removes residual toner on the photosensitive drum 1.

FIG. 2 is a diagram schematically showing the effect of the toner receiving member 7 of the embodiment shown in FIG. First, let us consider why toner (T in FIG. 2) floating and scattering near the transfer section occurs. To confirm this, when the copying operation was continued in the state shown in FIG. 6 and the transfer corona discharge means 5 was deactivated, the transfer guides 8 and 9 were not stained with toner at all. On the other hand, when the normal copying operation was continued in the state shown in FIG. 6 without feeding the transfer material P, the transfer guides 8.9 became stained as shown in FIG. 7. From the above, it can be understood that floating and scattered toner is caused by transfer corona discharge. Next, the second
The reason why the scattered toner is attracted to the toner receiving member in the illustrated configuration will be explained. The current flowing through the toner receiving member 7 is measured to be 10 to 3 μA, while the current flowing through the transfer guide 8.9 is ~10 μA or less, and under the same conditions, the current flowing through the toner receiving member 7 is 172 μA. ~1/3. The current flowing through the transfer guide 8.9 is transferred to the toner receiving member 7.
Even without it, there wasn't much of a change.

Since the toner receiving member 7 is closer to the transfer corona discharge means 5 and has a lower potential than the transfer guide 8.9, the current due to the transfer corona discharge is greater than the current flowing through the transfer guide 8.9. Since a large amount of transfer current (as shown by the arrow) due to the transfer corona discharge flows through the toner receiving member 7, the corona diagram due to the transfer corona discharge and toner floating and scattering due to the transfer corona discharge are also guided to the toner receiving member 7. The floating/scattered toner is not scattered from the image carrier due to the rotation of the image carrier, but is caused by transfer corona discharge. - All scattered toner is collected. Therefore, toner does not adhere to the transfer guides 8, 9, and there is no need to change the transfer guides 9 either electrically or in position.

Furthermore, because of the toner receiving member 7, toner scattering to the transfer corona discharge means is extremely small.

In the embodiment shown in Fig. 1, the copying operation is performed 10 times in the state shown in Fig. 6.
I made 0 copies. At that time, the potential of the transfer guide 8.9 is 5oo
v,) - The knur receiving member 7 was grounded. After the copying operation under the above conditions, copying was performed using the copying material with the maximum image width, but there was no staining on the back of the transfer material, and there was no staining on the transfer guides 8.9. However, it was observed that the floating/scattered toner penetrated deep into the toner receiving member 7 and was collected. (Second drawing section) Therefore, the recovery capacity is relatively high, and there is no need for special maintenance. Note that the toner receiving member 7 has the same length in the axial direction as the transfer guide 8.9.

In the embodiment shown in FIG. 1, when the toner used contains a magnetic material, if the transfer guide 8.9 is made of a magnetic material, it attracts the toner by magnetic force. Although the amount is small, it occurs even if the toner receiving member 7 is present. Therefore, it is preferable that the transfer guide 8.9 and the receiving member 7 are also made non-magnetic. It would be better if the toner receiving member 7 is made of a magnetic material in order to attract the toner, but if it becomes magnetized, the transfer guide 8
．． 9 as well, so it is better to make it non-magnetic. Specifically, the transfer guide 8.9 is 5US304.5US.
316, aluminum, conductive plastic, semiconductive plastic (in this case, the constant voltage element 10 is removed), etc. On the other hand, as the toner receiving member 7, 5US304.5U
Examples include S316, aluminum, and conductive plastic.

[Other Embodiments] In FIG. 3(a), the toner receiving member 7 and the lower transfer guide 9 are integrally formed and have the same potential. (It is shown as 13 in the figure.) According to this method, it can be made at low cost because it is made in one piece, and since the potential is the same, no extra wiring is required.

In addition, since the shape of the toner receiving portion of the lower transfer guide and toner receiving member 13 is made wide as shown in the figure, a sufficient volume of collected toner can be obtained.

FIG. 3(b) shows an example in which the upper transfer guide 8 is grounded via the toner receiving member 7 and the resistor R1 constant voltage element 1o, and the toner receiving member 7 is configured diagonally as shown in the figure, and the toner receiving member 7 is configured diagonally as shown in the figure, and the toner receiving member 7 is collected. When there is a large amount of toner, it is made to fall naturally from the toner receiving member 7. By doing this,
Even if a large amount of toner accumulates, it will fall off naturally, allowing the machine to be used for a long time.

Note that the position where the toner falls is set at a position that does not affect the mechanical structure, but it is better to install something like a collection box at the position where the toner falls.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a transfer device that prevents staining of the back surface of a transfer material.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention. FIG. 2 is an enlarged schematic diagram illustrating the effect of FIG. 1. FIGS. 3(a) and 3(b) are partial sectional views showing other embodiments of the present invention. FIGS. 4 and 5 are cross-sectional views illustrating a conventional example. FIG. 6 is a perspective view showing a portion of non-transferred toner on the image carrier. FIG. 7 is a perspective view showing how the transfer guide is dirty. 1... Image carrier 5... Transfer corona discharge means 7...
..... Toner receiving member 8.9 .... Transfer guide 10 ..... Constant voltage element P ..... Transfer material R ..... Resistance element 1υ

Claims (3)

[Claims] (1) In a transfer device that transfers a toner image formed on an image carrier onto a transfer material using a transfer means, there is no contact with the transfer material between the transfer material guide member that guides the transfer material to the surface of the image carrier and the transfer means. 1. A transfer device, characterized in that a toner receiving member is provided in the transfer device, and the potential of the toner receiving member is set to be the same as or lower than the potential of the transfer material guide member. (2) The transfer device according to claim 1, wherein the toner has magnetism, and the transfer material guide member and the toner receiving member are each non-magnetic members. (3) The transfer device according to claim 1 or 2, wherein the transfer means is a transfer corona discharge means.