JPH079160Y2 - Transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a transfer device used in a color electrophotographic copying machine or the like.

[Prior Art] Conventionally, in the above-mentioned color electrophotographic copying machine, a transfer drum whose surface is made of a derivative is provided in the vicinity of a photosensitive drum capable of forming toner images of a plurality of colors, and the transfer drum is formed on the surface of the photosensitive drum. Some toner images are sequentially transferred onto a transfer sheet held on the surface of a transfer drum to obtain a color image.

As the transfer device for transferring the toner image, a transfer corotron is provided on the back side of the transfer drum closest to the photoconductor drum, and the transfer corotron is electrostatically charged from the surface of the photoconductor drum to the surface of the transfer drum. A transfer sheet is used in which a toner image is transferred onto the transfer sheet held by.

However, in the case of the above transfer device, when the toner image on the photosensitive drum is transferred, it is charged from the back side of the transfer drum by the transfer corotron having a polarity opposite to that of the toner image.
The transfer sheet is attracted to the photosensitive drum side. for that reason,
Even if the front edge of the transfer paper is held on the transfer drum by a gripper, etc., the trailing edge of the transfer paper is not separated from the photoconductor drum and is attracted to the transfer drum, causing the toner image to be misaligned. There was a problem that jam occurred. Further, since the transfer drum is made of a dielectric material, the transfer drum holds the charging potential received by the transfer corotron as it is and is in a state of being charged to a high voltage. Therefore, when the transfer sheet receives the toner image from the surface of the photoconductor drum and is separated, an air breakdown (air discharge) occurs toward the transfer drum, and the discharge causes transfer to the surface of the transfer sheet. There is a problem that the toner image is scattered and the image is disturbed.

Therefore, as a means for solving the above problems, Japanese Patent Laid-Open No.
The one shown in Japanese Patent Publication No. 57-198478 has been proposed.
This is a transfer device that multiple-transfers a developed image on an image carrier onto a transfer material held by a transfer material carrier that circulates, and a transfer corona discharge device facing the image carrier,
Transfer material carrying means having a surface made of a dielectric material, which carries a transfer material on the surface and moves between the transfer corona discharge means and the image carrier, and a needle provided immediately after the transfer material is separated from the image carrier It is configured to have a needle-shaped conductive member in which conductive members that are sharpened in a line are arranged at predetermined intervals. Then, when the transfer material is separated from the image carrier, discharge is performed from the needle-shaped conductive member onto the transfer material, and the surface of the transfer material is charged to a polarity opposite to the charging polarity of the transfer corona discharge means, The attracting force between the transfer material and the transfer material carrying means is increased to prevent the toner image to be transferred from being displaced.

[Problems to be Solved by the Invention] However, such a conventional technique has the following problems. That is, in the case of the above-mentioned conventional technique, the transfer material is charged by discharging from the needle-shaped conductive member on the transfer material immediately after being separated from the image carrier, and to a certain degree with the charging of the back surface side of the transfer material carrying means. By balancing, the attraction force between the transfer material and the transfer material carrying means is strengthened to prevent the transfer material from winding around the transfer material carrying body.
The effect is certainly recognized in that respect. However, in the case of the above-mentioned conventional technique, as shown in FIG. 8, since the discharge electrodes are needle-shaped sharp conductive members 30, 30 ... Arranged at a predetermined interval, the discharge is needle-shaped. Arises only from part 30,
Discharge cannot be generated uniformly. Therefore, when the transfer material is charged by the discharge, the toner image transferred on the transfer material is unevenly discharged into a scaly shape or a circular shape as shown in FIG. However, there is a problem that color misregistration occurs. In particular, with transfer materials with high resistance such as low water content paper and OHP sheets, there is almost no movement of charges on the transfer material.Therefore, if the discharge is uneven, the effect directly appears and toner scattering occurs. However, there is a problem that the toner image is disturbed. Therefore, in the case of the prior art described in the above-mentioned JP-A-57-198478, while having the advantage that the transfer can be performed well,
In the case of a color copying machine, there is a big problem in terms of image quality of a toner image which is particularly important.

[Means for Solving Problems] Therefore, the present invention has been made to solve the problems of the above-described conventional technology, and the purpose thereof is to achieve uniform discharge and toner scattering. It is an object of the present invention to provide a transfer device capable of obtaining a high-quality image without causing such problems.

In this invention, a transfer corotron is provided on the back surface side of the transfer material holder at the position closest to the toner image carrier and the transfer material holder, which are rotatably arranged close to each other, and the toner image is transferred by this transfer corotron. In the transfer device configured to transfer the toner image formed on the surface of the carrier to the transfer material held on the surface of the transfer material holder, the closest position between the toner image carrier and the transfer material holder. In the vicinity of the downstream side in the rotation direction of, the static elimination member that acts in a non-contact manner on the toner surface of the transfer material is arranged. It is configured to be planted and formed in the shape of a brush.

Further, in this invention, the resistance value of the static elimination member formed by fixing the whole of the large number of conductive fibers with an adhesive and implanting them in a uniform and dense brush plate shape is 10 ³ Ω / cm or less. It is desirable to set.

As the toner image carrier, for example, a photosensitive drum is used, and images of yellow, cyan, magenta, etc. are sequentially formed on the surface thereof.

As the transfer agent, for example, transfer paper is used, but the transfer agent is not limited to this, and an OHP sheet or the like may be used as long as the toner image can be transferred.

As the transfer material holder, for example, a transfer drum whose surface is made of a dielectric material is used.

As the conductive fiber, for example, carbon fiber or stainless fiber is used. Also, this conductive fiber, for example
It is planted and used at a density of 37,500 lines / cm.

[Operation] In this invention, since the static elimination member is formed by implanting the dielectric fibers in a uniform and dense brush shape, it is possible to uniformly discharge the conductive fibers by the uniformly and densely implanted conductive fibers. it can.

In addition, in this invention, by fixing the conductive fibers with an adhesive, a large number of conductive fibers can be surely planted in a more uniform and dense brush shape, and the conductive fibers can be reliably removed. Therefore, it is possible to prevent the conductive fibers from falling off and giving a defect to the image.

Further, in this invention, since a large number of conductive fibers are planted in a brush shape by hardening the conductive fibers with an adhesive, the static elimination member can be formed in a small size (thin shape). The static elimination member can be easily arranged in the vicinity of the downstream side of the closest position between the toner image carrier and the transfer material holder in the rotational direction.

Further, in this invention, the resistance value of the static elimination member formed by fixing the large number of conductive fibers with an adhesive and implanting them in a uniform and dense brush shape is set to 10 ³ Ω / cm or less. Desirably, in such a case, even if the static elimination member is formed by fixing a large number of conductive fibers with an adhesive and implanting them in a uniform and dense brush shape, the large number of conductive fibers are fixed to each other by adhesion. It is possible to reliably prevent the static elimination efficiency from gradually decreasing due to the adhesive being charged.

[Embodiment] The present invention will be described below based on an illustrated embodiment.

FIG. 4 shows a color electrophotographic copying machine to which the transfer device according to the present invention can be applied. In the figure, reference numeral 1 denotes a document placed on the contact glass 2.
The image of is illuminated by the light source 3. The reflected light image from the manuscript 1 has a full rate mirror 4, a half rate mirror 5,
6, through the lens 7 and the fixed mirror 8, the photosensitive drum 9 as a toner image carrier is scanned and exposed. At this time, a color separation filter 10 is interposed between the fixed mirror 8 and the photoconductor drum 9. By sequentially switching the color separation filters 10, the image of the original 1 is color separated and scanning exposed. Is able to. The photosensitive drum 9 is pre-charged by the corona charger 11 prior to image exposure, and then the image of the original 1 is exposed as described above to form an electrostatic latent image. This electrostatic latent image is developed by the developing device corresponding to the color of the color-separated image among the developing devices 12, 13, 14 of yellow, magenta, and cyan colors arranged around the photosensitive drum 9. As a result, a toner image is formed, which is transferred onto a transfer sheet held on a transfer drum described later. After that, the residual toner on the surface of the photoconductor drum 9 is removed by the cleaner 15, and image formation with different colors is repeated a predetermined number of times.

A transfer drum 16 as a transfer material holding means is rotatably arranged near the photoconductor drum 9, and a portion of the transfer drum 16 that holds a transfer sheet 17 as a transfer material is made of a dielectric material 18. Has been formed. The transfer drum 16 grips the front end of the transfer paper 17 with a gripper and electrostatically adsorbs and holds the transfer paper. Inside the transfer drum 16, a transfer corotron 19 forming a part of the transfer device according to the present invention is arranged at a position closest to the photosensitive drum 9, and is formed on the photosensitive drum 9. The toner image is electrostatically transferred onto the transfer paper 17 held on the transfer drum 16.

Then, the yellow, cyan, and magenta toner images sequentially formed on the photosensitive drum 9 are transferred to the transfer drum.
The transfer paper 17 is held on 16 and sequentially transferred onto the transfer paper 17, and then the transfer paper 17 is separated from the transfer drum 16 and fixed.
The toner image is fixed on the transfer paper 17 by means of 20, and a dark image is obtained.

By the way, in this embodiment, a static elimination member is arranged on the downstream side in the rotational direction of the closest position between the photoconductor drum and the transfer drum, and the static elimination member is made of conductive fibers in a uniform and dense brush shape. It is formed by planting. That is, as shown in FIG. 3, the static elimination member 21 is a frame of the device.
22 is attached to the tip of an arm 23 whose base end is pivotally supported by 22, and when removing the jammed transfer paper 17, by rotating the arm 23 and moving the charge eliminating member 21,
The transfer paper 17 can be easily removed.

As shown in FIG. 1, the static eliminating member 21 has a conductive fiber 24.
Are planted in a uniform and dense brush shape. The conductive fiber 24 is cut into a predetermined length of about 1 cm and is arranged in a uniform and dense brush shape. The base end portion of the conductive fiber 24 arranged in the brush shape is shown in FIG. As shown, the double-sided tape is sandwiched between the aluminum plates 25 that are bent in a U shape, and is affixed to the inner surface of the aluminum plate 25.
The conductive fiber 24 is held by the aluminum plate 25 by 26. The Alni plate 25 is connected to the ground.

As the conductive fiber 24, for example, carbon fiber (trade name: Torayca, manufactured by Toray Industries, Inc.) is used. This conductive fiber
24 is a carbon fiber having a diameter of 7 μm and a volume resistivity of 2.0 × 10 ³ Ω · cm. And, this conductive fiber 24 is a static elimination member.
The number of 21 per 1 cm is arranged at a density of 37,500 lines / cm, for example. The resistance value of the static eliminating member 21 thus formed is
It is preferably 10 ³ ohm or less per cm.

The conductive fiber 24, while sandwiching the base end portion between the aluminum plate as described above, is not formed into a brush shape by adhering with a double-sided tape, but to a plate shape using an adhesive to the tip end portion thereof. It may be hardened.
In such a case, it is possible to reliably prevent the conductive fiber 24 from coming off and adversely affecting nearby electric components. However, when the conductive fibers 24 are bundled with an adhesive, the adhesive is generally a dielectric, and therefore, when the conductive fibers 24 are discharged as described below, the adhesive is charged with a polarity opposite to the discharge polarity. This will cause the discharge electrode to decay. Therefore, when the conductive fibers 24 are hardened with an adhesive and formed into a brush shape, the resistance value per 1 cm of the static elimination member 21 is preferably 10 ³ ohms or less.

With the above configuration, in the transfer device according to this embodiment,
The toner image is transferred onto the transfer sheet as follows. That is, when the toner image formed on the photosensitive drum 9 moves to the transfer position near the transfer drum 16,
By the charging of the transfer corotron 19, the toner image on the photosensitive drum 9 is transferred onto the transfer paper 17 held on the surface of the transfer drum 16. At that time, since the transfer drum 16 is formed of a dielectric material, the back side of the transfer drum 16 is charged by the transfer corotron 19 and is positively charged to a high voltage of about 1 KV. Then, the transfer paper 17 on which the toner image has been transferred is separated from the photosensitive drum 9 and transferred to the transfer drum 16.
Although it moves to the downstream side in the rotation direction with the rotation of, the discharging member 21 connected to the ground is provided on the downstream side in the rotation direction of the transfer drum 16. Therefore, as shown in FIG. 5, from the tip of the charge removing member 21, immediately after the transfer paper 17 is separated from the photosensitive drum 9, air discharge toward the transfer drum 16 charged to a high voltage is performed. Then, the surface of the transfer paper 17 is negatively charged. Therefore, the transfer sheet 17 is securely held on the transfer drum 16 because the negative charge charged on the surface thereof is attracted to the positive charge charged on the back surface side of the transfer drum 16, so that the image to be transferred is transferred. There will be no misalignment.

Further, since the static elimination member 21 is formed by implanting the conductive fibers 24 in a uniform and dense brush shape, it is possible to generate a uniform and sufficient discharge from the tip of the conductive fibers 24. Therefore, since the discharge can uniformly charge the transfer paper 27, the non-uniform discharge does not disturb the toner image transferred on the transfer paper 17 and deteriorate the image quality unlike the conventional case. Therefore, a high quality image can be obtained. In particular, in the case of a color image, it is possible to prevent the toner image of each color from being disturbed, so that a satisfactory color image without color misregistration can be obtained.

The inventor of the present invention prototyped the transfer device having the above-described configuration and removed the charge removing member 21.
The discharge current from the conductive fiber 24 was measured by variously changing the resistance value of. FIG. 6 shows the result of the above measurement. As is clear from this figure, in the case of this embodiment, A,
It was found that the smaller the resistance value of B and C, the larger the discharge current, which is preferable. In the figure, D indicates the value of the conventional device, and it was found that when the needle-shaped conductive members were arranged at regular intervals as in the conventional device, the discharge was non-uniform and the discharge current was small. .

In addition, FIG. 7 shows the result of measuring the state of change of the discharge current when the conductive fiber 24 is fixed with an adhesive or the like to increase the resistance value of the static eliminating member 21 and continuously discharge. Is. As is clear from the figure, when the resistance value is large, the discharge current decreases with time. It is considered that this is because the adhesive or the like that increases the resistance value is made of a dielectric material, and thus the adhesive itself is charged with time and the discharge efficiency is reduced.

[Advantages of the Invention] The present invention having the above-described structure and operation can perform uniform charging, prevent toner from scattering, and obtain high-quality images.

In addition, in this invention, by fixing the conductive fibers with an adhesive, a large number of conductive fibers can be surely planted in a more uniform and dense brush shape, and the conductive fibers can be reliably removed. Therefore, it is possible to prevent the conductive fibers from falling off and giving a defect to the image.

Further, in this invention, since a large number of conductive fibers are planted in a brush shape by hardening the conductive fibers with an adhesive, the static elimination member can be formed in a small size (thin shape). The static elimination member can be easily arranged in the vicinity of the downstream side of the closest position between the toner image carrier and the transfer material holder in the rotational direction.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a charge eliminating member of a transfer device according to the present invention, and FIG. 2 is a sectional view showing the charge eliminating member.
FIG. 4 is a side view showing the transfer device, and FIG. 4 is a schematic view showing a color electrophotographic copying machine to which the present invention can be applied.
5 is an explanatory view showing the operation of the apparatus shown in FIG. 3, FIGS. 6 and 7 are graphs showing measured values, FIG. 8 is an explanatory view showing the operation of the conventional apparatus, and FIG. It is a top view which shows the image transferred by the conventional apparatus. [Explanation of reference symbols] 9: photoconductor drum 16: transfer drum 17: transfer paper 19: transfer corotron 21: static eliminator 24: conductive fiber

Claims (2)

[Scope of utility model registration request] 1. A transfer corotron is provided on the back surface side of the transfer material holder at the position closest to the toner image carrier and the transfer material holder, which are rotatably arranged close to each other, and the toner is transferred by the transfer corotron. In a transfer device in which a toner image formed on the surface of an image carrier is transferred onto a transfer material held on the surface of a transfer material holder, the toner image carrier and the transfer material holder are closest to each other. A static eliminator that acts in a non-contact manner on the toner surface of the transfer material is arranged in the vicinity of the downstream side in the rotational direction of the position. Transfer device, which is formed by implanting in a plate shape of a simple brush. 2. The static elimination member formed by fixing the whole of a large number of conductive fibers with an adhesive and implanting them in a uniform and dense brush plate shape has a resistance value of 10 ³ Ω / cm or less. The transfer device according to claim 1, wherein the utility model is registered.