JPH0710360Y2 - Image recording device transfer device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transfer device of an image recording device.

As a full-color image recording apparatus using the conventional electrophotographic method,
A color separation image superposition transfer system is generally used. As one of the recording devices of this system, as shown in FIG. 6, the originals on the four photoconductor drums 1A, 2A, 3A and 4A are blue, green and red.
The image information light separated into the colors is read, and the write image data to be developed in each color of yellow, magenta, cyan, and black is obtained by performing the image calculation process based on the intensity level of each color light. Optical writing is performed based on the obtained electrostatic latent image yellow provided on each photoconductor drum,
Developer that contains magenta, cyan, and black developers
1B, 2B, 3B, 4B phenomenon occurs, the toner image of each color formed on each photoconductor drum, through the registration roller 7 from the paper feed unit to each photoconductor drum in sequence, to the transfer belt 5 that rotates,
The transfer belt 5 is sandwiched between the transfer papers that are electrostatically adsorbed and conveyed, and the transfer belts 5 are sandwiched by the transfer chargers 1C, 2C, 3C, and 4C that oppose the photosensitive drums. 2. Description of the Related Art A color image recording apparatus is known in which a full-color image can be obtained by performing a transfer with a match and then fixing it with a fixing roller 8.
In the illustrated example, the color-separated image information is optically color-separated by the document reading unit 9 provided on the upper portion of the image forming apparatus main body,
Each photoconductor drum is read by three CCDs 10 and each color image data obtained by arithmetic processing based on the output signal
Writing is performed by blinking the laser light sources opposite to 1A, 2A, 3A, and 4A.

The transfer belt 5 is made of a dielectric material such as polyester film, and is charged by the transfer chargers 1C, 2C, 3C, and 4C, so that the charge is removed from both sides by the charge removal charger 6 to be initialized, and the image is ready for the next image transfer. As a transfer charger, one having a structure in which a corona discharge wire is stretched in a shield plate extending in the width direction of the photoconductor is widely used.

However, in a transfer device using a dielectric belt, a backup member supporting the belt from the back side of the transfer belt is necessary in order to improve the adhesion between the transfer paper conveyed to the dielectric belt and the photoconductor. This backup member is made into a roller shape as shown by reference numeral 11 in the drawing, and is rotated together or driven at the same linear velocity as the belt in order to reduce the transfer load of the transfer belt as much as possible. Further, this roller is made of a metal material in order to obtain cylindricity, and is generally grounded. In this case, the transfer belt that has adsorbed the transfer paper that has passed through the transfer position is charged by the transfer charge, and the toner on the transfer paper that is adsorbed on the belt is charged by the transfer charge on the belt and that on the transfer paper that is adsorbed on the belt. The toner is stable because it creates an electric field in the vertical direction by the transfer charge of the belt.

However, when the backup member rapidly approaches or contacts the electric field generated between the belt and the backup member, the electric field applied to the toner is abruptly disturbed, and a horizontal electric field is particularly likely to be generated, and the toner scatters in that direction.
The image becomes disordered and causes an abnormal image. In addition, when the electric field is suddenly separated from the backup member, the same electric field disturbance as described above occurs, or as another cause, the electric potential between the belt and the backup roller rises as the distance increases and peeling discharge occurs, and the electric charge on the backside of the belt increases. Are neutralized, the force for restraining the toner is lost, the toner becomes easy to move, and similarly the image is disturbed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer device that prevents the occurrence of image distortion on a transfer paper in view of the above-mentioned actual situation of image distortion due to a backup belt backup member.

In order to achieve the above-mentioned object, the present invention provides a transfer device having the above-mentioned configuration, by placing the transfer paper close to the back surface of the transfer belt from immediately after the transfer position on the most upstream side to the position where the transfer paper leaves the transfer belt. The member is arranged, and the distance between the edge of the shield plate of the transfer charger and the point on the back surface of the transfer belt immediately above it is the distance between the point on the back surface of the transfer belt and the edge of the conductive member. It is characterized in that it is not less than the distance between them.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the transfer device of the image recording device shown in FIG. In this embodiment, a metal electric field stabilizer 12 is provided between the transfer chargers 1C, 2C, 3C and 4C and the backup roller 11 so as to uniformly contact the back side of the upper portion of the transfer belt 5.

This electric field stabilizer prevents the transfer belt from approaching or moving away from the backup roller 11 and prevents abrupt changes in the electric field. Therefore, the electric field applied to the toner on the transfer paper conveyed on the transfer belt 5 is prevented. It is stable and image distortion is prevented. Further, since the electric field stabilizer 12 is provided close to the back surface of the transfer belt 5, the potential increase between the belt 5 and the backup roller 11 or the electric field stabilizer 12 is small, and the peeling discharge is also reduced.

The electric field stabilizer 12 is kept at a constant potential by being grounded or grounded via a resistor or a constant voltage element. Also,
Although the electric field stabilizer is made of metal here, the same effect can be obtained if it is made of a conductive material such as a conductive resin.

In another embodiment shown in FIG. 2, the backup roller is not provided on the back surface of the upper portion of the transfer belt 5, but the electric field stabilizer 13 has an arc-shaped cross section and its back portion is brought into contact with the back surface of the transfer belt 5 to function as the backup roller. It shows an example in which it is also used.

The electric field stabilizer may be provided outside the belt,
In that case, the stabilizer will be on the transfer paper side.Therefore, if the distance between the outer surface of the belt and the stabilizer is too close, the transfer paper will be easily adsorbed by the stabilizer, which may result in conveyance failure. is necessary.

The effect of preventing image distortion by the electric field stabilizer may vary depending on the positional relationship between the edge of the shield plate of the transfer charger and the edge of the electric field stabilizer on the transfer charger side. It turned out as a result of an experiment by the inventor.

Hereinafter, this point will be described in detail with reference to FIG.

FIG. 3 is an enlarged view showing the vicinity of the transfer charger 1C of the embodiment shown in FIG. In the figure, the leg of the perpendicular line descending from the edge D of the shield plate 14 of the transfer charger 1C to the back surface of the transfer belt 5 is E, the distance of DE is l ₁ , and the electric field stabilizer 13 on the transfer charger 1C side. The distance between the edge F and the point E is l ₂ . The toner image formed on the photoconductor 1A is transferred on the transfer belt 5 onto the transfer paper conveyed from right to left in the figure under the action of the transfer charger 1C. In this case, the force holding the transferred toner depends on the distance between the electrodes, so if (l ₁ −l ₂ ) is a value smaller than zero, the electric field applied to the toner will be Changes suddenly in the area, appearing as image distortion. FIG. 5 is a graph showing the image rank (“good” when there is no image distortion and “bad” when the image distortion is severe) due to changes in (l ₁ −l ₂ ).

Therefore, by arranging the shield plate 14 and the electric field stabilizer 13 of the transfer charger 1C so that l ₁ −l ₂ ≧ 0, that is, l ₁ ≧ l ₂ , after the toner is transferred to the transfer paper,
Even when the transfer charger 1C is advanced under the influence of both the shield plate 14 and the electric field stabilizer 13 of the transfer charger 1C, good image quality can be obtained without a sudden change in the electric field.

In another embodiment of the present invention shown in FIG. 4, a transfer charger is provided.
The 1C, 2C, and 3C shield plates 14 and the electric field stabilizer 13 are connected at their respective ends to be integrated, and l ₁ = l ₂ . Therefore, the electrodes are continuous and can be said to be an ideal type.

In each of the above-mentioned embodiments, the transfer belt is in contact with a plurality of photoconductors to perform the superposed transfer. However, in the case where there is only one photoconductor drum, the same transfer separation system as in the above example may be used. The present invention is effective.

In the embodiment shown in FIG. 1, the backup roller 11 is in contact with the belt 5 and the electric field stabilizer 12 is in contact with and close to the belt 5. In the embodiment shown in FIG. 2, the electric field stabilizer 13 is partially in contact with the belt 5.

However, the gap between the non-contact portion and the belt is small, and it was recognized from the experimental results that the disturbance of the electric field and the image disturbance due to the peeling discharge do not occur.

In the embodiment of FIG. 2, the electric field stabilizer is also used as the backup member. However, since the contact area of the electric field stabilizer contacting the belt is small, it does not become a load that reduces the belt conveying force. Good transportability was obtained.

Effects As described above, according to the present invention, the electric field is stable and a good transferred image can be obtained.

[Brief description of drawings]

1 and 2 are side sectional views showing an embodiment of the present invention, FIG. 3 is a partially enlarged sectional view of the embodiment shown in FIG. 2, and FIG. 4 is a side view showing another embodiment of the present invention. FIG. 6 is a cross-sectional view, and FIG. 5 is a graph qualitatively showing the positional relationship between the end of the electric field stabilizer and the end of the shield plate of the transfer charger with respect to the transfer belt and the image rank in the embodiment shown in FIG. FIG. 1 is a side sectional view showing an example of a conventional image recording apparatus. 1A, 2A, 3A, 4A …… Photoconductor drums 1C, 2C, 3C, 4C …… Transfer charger 5 …… Transfer belt 6 …… Static charge charger 11 …… Backup member 12, 13 …… Conductive electric field stabilizer 14… … Shield plate for transfer charger

Claims (1)

[Scope of utility model registration request] 1. A toner image formed on a plurality of photoconductors is spread in the widthwise direction of the photoconductors on the same transfer paper which is conveyed by a transfer belt made of a dielectric that rotates in contact with these photoconductors. Corona discharge wire is stretched inside the shield plate provided, and the image is recorded by sequentially superposing and transferring the image under the action of the transfer charger which is sandwiched between the transfer belt and the photoconductor. In the transfer device of the apparatus, a conductive member is arranged close to the back surface of the transfer belt from immediately after the transfer position on the most upstream side to a position where the transfer paper leaves the transfer belt, and the edge of the shield plate of the transfer charger is disposed. And a point on the back surface of the transfer belt immediately above the transfer belt is equal to or more than a distance between the point on the back surface of the transfer belt and the edge of the conductive member.